Project Trinidad, Explosive Excavation Tests

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Cameron S t a t i o n , Alexandria, V i rg in i aL 22314ior Nat ional Technical Information S e : v i c e , h

P r i n t e d i n USA. Avai lable from Defense Doiumentation Center

U. S. Department of Commerce:, il Spr ing f i e ld , V i r g i n i a !I

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DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

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TID -4500, UC-35

TECHNICAL REPORT E-73-1.

PROJEC T TRINIDAD EXPLOSIVE EXCAVATION TESTS IN

SANDSTONE AND SHALE

BRUCE B. REDPATH

N O T I C E ' This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Atomic Energy Commission, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights,

C ond ucted by

U. S. ARMY ENGINEER WATERWAYS EXPERIMENT STATION

EXPLOSIVE EXCAVATION RESEARCH LABORATORY LIVE RMOR E , CALIF OR N IA

MS. date: J u l y 1972 a

lB=STRIBUT!QN OF THIS OOCUMENT IS UNLlMlT 0

Foreword 4-

The Explosive Excavation Research Laboratory (EERL)-' is embarked on a program of research in topical a r eas cri t ical to the overall technology that is referred to a s "explosive excavation.'' This is the report of a complete program of explosive excavation experiments, and includes summaries of the related technical programs such a s seismic effects, airblast generation, and engineering properties of a large c ra t e r excavated for a railway cut. The report is primarily oriented towards the cratering aspects of the program, for indeed, the acquisition of the cratering characteristics of a weak rock and the verification of row-charge design rules were the principal goals in conducting the experiments. project was a successful demonstration of the economic benefits of explosive excavation. Two additional railway cuts la ter excavated in the same a rea represented immediate and beneficial applications of the knowledge acquired during the project, and this same knowledge wi l l continue to contribute to the mission of EERL.

The excavation of a railway cut at the conclusion of the

a :: The U. S. Army Engineer Waterways Experiment Station (USAEWES) Explosive Ex-

cavation Research Laboratory (EERL) was the USAEWES Explosive Excavation Research Office (EERO) from 1 August 1971 to 2 1 April 1972. a s the USAE Nuclear Cratering Group (NCG).

P r io r to that time, it was known

Abstract . 1

A series of single-, row-, and multiple-charge cratering detonations, with individual charge weights of 1 to 2 tons, were carried out in weak, 1 idterGedded sandstones and shales near Trinidad, Colorado, in 1970 and 1971. The principal objectives of these excavation experiments were to obtain single-charge cratering curves, to’ verify row-charge designs for achieving a specified excavation, to, determine the effects of millisecond delays in row-charge cratering, to experiment with cratering in varying terrain, and to compare the cratering effectiveness of several explosives. Three var i - eties of aluminized ammonium-nitrate blasting agents and ANFO were used. *Airblast and seismic effects of each detonation were monitored. excavation of a railway cut 400 f t long with 44 tons of explosives distributed among 32 charges.

The s e r i e s culminated with the

Acknowledgments

This report is the outcome of the efforts of many people involved in Project Trinidad. Gardner, also wrote Chapter 6; LT Dale Mc Williams contributed significantly to Chapter 4; and Charles Snell prepared Chapter 5.

Director. operational support throughout the project. Hensinger of the Albuquerque District contributed significantly to the efficient accomp- lishment of the experimental program. the successful conduct of their respective technical programs in the field, and to them is due the credit for the overall success of the project.

LT T e r r y Shackelford wrote Chapter 2 and, together with MAJ Charles

MAJ Richard Gillespie w a s Test

The Albuquerque Engineer District provided outstanding contractual and Messrs . Wayne McIntosh and Victor

All of the people above were responsible for

Appendix E was written by Prof. J. M. Duncan and M r . C. K. Chan of the University of California, Berkeley; this work was performed by Prof. Duncan and Mr. Chan under contract DACW07-71-C-0032 with the University of California, Berkeley.

Mills, Jr. w e r e Directors of EERL during the course of the field work and the preparation of this report.

COL William E. Vandenberg, LTC Robert L. LaFrenz, and LTC Robert R .

- iv-

Contents

FOREWORD . ii

ABSTRACT . iii ACKNOWLEDGMENTS . . iv CONVERSION FACTORS . x CHAPTER 1. INTRODUCTION . . 1

General . 1 Background and Objectives . . 1

Scope of Program . . 2 Project Organization . 4

CHAPTER 2. SITE DESCRIPTION . 4 Location and Topography . 4 Geology . 5

. 6

CHAPTER 3. CRATER MEASUREMENTS . 7

B-Series . . 8 C-Series . 12

Simultaneous Rows (Cl, C2, C3) . . 13 Delayed Row-Charges (C4, C5) . . 17 Double Row-Charge Detonation (C6) . . 1 7

Single Row- Charge through Varying Te r ra in (Dl) . . 18 Single Row-Charge along a Sidehill (D2) . . 23 Double Row-Charge along a Sidehill (D3) . .' . 25

Preshot Engineering Propert ies of Site Medium

D- Series . 18

Delayed Double Row-Charge (Railway Cut, D4) . 27 CHAPTER 4. SEISMIC MEASUREMENTS . . 32

Scope . . 32 Results . 35

CHAPTER 5. AIRBLAST MEASUREMENTS . 36 Scope . . 36 Results . 37

CHAPTER 6. ENGINEERING STUDIES O F D4 CRATER . 39 Introduction . 39 On-Site Investigative P rograms . . 39 Mass Density and Bulking Factor . . 39 Field Determination of Particle Gradation . . 39 Drilling, Coring, and Borehole Photography . . 40 Shaping of Railroad Cut . . 41 Fallback Compaction and Field Settlement Study . 42

CHAPTER 7. CONCLUSIONS APPENDIX A DRILL HOLE LOCATIONS, STRATIGRAPHY

APPENDIX B CRATER PROFILES AND CROSS SECTIONS APPENDIX C SEISMIC DATA . APPENDIX D AIRBLAST DATA APPENDIX E REFERENCES . FIGURES 1. Organization of Project Trinidad .

AND LITHOLOGY, AND MATERIAL PROPERTIES DATA

LABORATORY TESTING OF FALLBACK MATERIAL

~ - - _ -

2. Project Trinidad site location 3.

4 . Engineering classification for intact rock . 5.

6. 7 . 8. Apparent c r a t e r r a d i i and depths for B se r i e s . 9.

Generalized stratigraphic section of Trinidad, Vermejo, and Raton formations .

Aerial view of principal experimental a r ea showing B

Bucket auger used to emplace charges Typical 1 -ton single-charge c ra t e r

series, C ser ies , and D4 c ra t e r .

Volumes of B se r i e s apparent c r a t e r s 10. C3 row c ra t e r . 11. Row c ra t e r enhancement v s charge spacing 12. Single-charge crater ing curves with row c ra t e r

13. Longitudinal profiles, charge layout, and c ross

14. D1 preshot te r ra in , charge layout, c ros s sections,

15. D1 c r a t e r . 16. Longitudinal profiles and c ross sections of D2 c ra t e r . 17. D2 c r a t e r . 18. Longitudinal profiles and cross sections of D3 c r a t e r . 19. D3 c r a t e r . 20. 21.

22. D4 detonation . 23.

24.

25.

26. 27.

dimensions superimposed

sections of C6 c r a t e r

and c ra t e r profile .

Anticipated c r o s s section and plan view of D4 experiment Chart of charge spacing vs depth of cut for 1- and 2-ton

charges of TD-2 s lu r ry in sandstone and shale

. .

D4 c r a t e r viewed from west to east along center

Cross sections of D4 railway cut showing comparison

Locations of se i smic monitoring stations during

Peak ground motion amplitudes vs distance Peak airblast overpressures for selected

Project Trinidad detonations . -vi-

line of railroad . between c ra t e r and cut excavated by conventional methods

P r o j e ct T r inid ad

.

. 44 a

. 47

. 54

. 62

. 65

. 78

. 92

. 3

. 4

. 5

. 7

. 8

. 3.0

. 10

. 10

. 10

. 15

. 15

. 1 6

. 19

. 2 1

. 2 2

. 24

. 25

. 2 6

. 2 6

. 28

. ' 28

. 29

.. 29

. 31

. 34

. 38

28. Map of D4 c r a t e r showing location of postshot

29. Location of core holes in D4 c ra t e r and extent of engineering investigations . 40

blast-induced fracturing (c ross section through Station 93+00) . 41 30. Dozer daylighting end of cut and bringing cut to grade . . 41

31. mater ia l f rom c ra t e r . 42

32. Finished cut . 42 33. Settlement marke r s . 42 34. Layout of settlement markers for vibratory compaction tests . 43 35. Bros smooth-roller vibratory compactor . . 43 36. Surface settlement produced by vibratory compaction tests . . 44

se r i e s and D4 railroad cut . 47

Dozer scales c ra t e r slopes; front loader removes

Al. Map showing location of core holes for B and C

A2.

A3. A4. A5. A6. B l . B2. B3. B4. B5.

Map showing location of emplacement and co re holes for Experiment D1, D2, and D3 . . 48

Stratigraphy and lithology of B s e r i e s . 49 Stratigraphy and lithology of C se r i e s . 49 Stratigraphy and lithology of Experiments D1, D2, and D3 . . 50 Stratigraphy and lithology of D4 railroad cut . . 50 Cra te r nomenclature . 54 Cross sections of c r a t e r s B1 and B2 . . 55 Cross sections of Cra t e r s B3 and B4 . . 56 Cross sections of Cra te rs B5 and B6 . . 57 Cross sections of Cra t e r s B7 and B8 . . 58

B6.

B7.

B8.

D1.

Longitudinal profiles and representative c ross sections

Longitudinal profiles and representative c r o s s sections

Longitudinal profiles and representative cross sections

Observed single-charge t ransmission factors as a function

for Rows C1 and C2 . . 59

f o r R o w C 3 . . 60

for Rows C4 and C5 . . 61

of scaled depth of burst for aluminized ammonium nitrate s lu r ry detonations, Project Trinidad . . 72

by point count technique and by sieving . 79

and for test specimens . . 80

maximum particle s i ze . . 81

E l . Comparison of grain-s ize distribution curves determined

E2. Grain-size distribution curves for mater ia l as received

E3. Variations of maximum and minimum density with

E4. Wet specimen (36-in. diameter) after testing . 82

E5. S t ress -s t ra in and volume change curves for specimens compacted to 7 1% relative density (confining pressure , 15 psi) . 83

compacted to 7 1% relative density (confining pressure, 30 psi) . . 83

E6. Stress -s t ra in and volume change curves for specimens

- vii -

E7. Stress-strain and volume change curves for specimens compacted to 7770 relative density (confining pressure, 15 psi) . compacted to 7 770 relative density (confining pressure, 30 psi) . compacted to 7 370 relative density (confining pressure, 15, psi) . compacted to 7 370 relative density (confining pressure, 30, psi) . compacted to three relative densities (confining pressure, 15 psi) . compacted to three relative densities (confining pressure, 30 psi)

Compression t ime curves for specimens compacted to 8070 relative density .

One-dimensional compression curves for specitr-ens compacted to 8070 relative density

One-dimensional compression curves for specimens compacted to 5070 relative density

Variations of angle of internal friction with relative density

Variation of volumetric s t ra in due to wetting with maximum particle s i ze .

Variation of compression due to wetting with overburden p res su re for a t - r e s t p re s su re conditions

E8. Stress-strain and volume change curves for specimens



E l l . Stress-strain and volume change curves for specimens


E13.

E14.

E l 5.

E16.

E17.

E18.

TABLES

1. 2. B-ser ies cratering charges , 3. 4. B-ser ies c ra t e r dimensions . 5. C-ser ies charge emplacement 6. Summary of row c r a t e r dimensions . 7. 8. Summary of D-series experiments 9. D1, D2, D3 charge emplacement .

Summary of Project Trinidad cratering experiments

Characterist ics of Project Trinidad explosives

Unit volumes for C-ser ies r o w c r a t e r s

10. D4 charge emplacement summary 11. Locations of seismic recorders , Project Trinidad . 12. Airblast damage c r i t e r i a

A l . A2. A3.

Results of tes t s of B-ser ies rock co res Results of t e s t s of C-se r i e s rock co res Results of tes t s of D-series rock co res

. 83

. 84

. 84

. 84

. 85

. 85

. 86

. 86

. 87

. 91

. 2

. 9

. 11

. 12

. 14

. 1 5

. 16

. 20 2 2

. 30

. 51

. 52

. 53

-viii-

C1. Maximum recorded particle velocities for B-ser ies C2. Maximum recorded particle velocities for C1, C2, C3 . C3. Maximum recorded particle velocities for C4, C5, C6 . C4. D1.

Maximum recorded particle velocities for D-series Close-in airblast observations for Detonations Bl through

B8 (single-charges). Altitude = 6200 f t AMSL; ambient p re s su re = 810 mbar

(row-charges). p re s su re = 810 mbar



D3 (row-charges). p re s su re = 810 mbar

D2a. Close-in airblast observations fo r Detonations C1 and C2 Altitude = 6200 f t AMSL; ambient

D2b. Close-in airblast observations for Detonations C3 and C4 Altitude = 6200 f t AMSL; ambient

D2c. Close-in airblast observations for Detonations C5 and C6 Altitude = 6200 ft AMSL; ambient

D3. Close-in airblast observations for Detonations D1 through Altitude = 6200 f t AMSL; ambient

D4. . D5a. Ground- shock-induced overpressure reinforcement correction

D5b. Gas -vent- induced overpressure reinforcement correction

D6. Airblast amplitudes for row-charges expressed in t e rms

El. Composition and specific gravities of various sized

E2. Va lues of particle breakage factor B determined by

E3. Summary of triaxial test results .

Close-in airblast observations for Detonation D4 (row-charges). Altitude = 6200 f t AMSL; ambient pressure = 810 mbar

factors for Trinidad row-charge detonations

factors for Trinidad row-charge detonations

of single-charge airblast amplitudes . fractions of Trinidad fallback

resieving triaxial specimens after testing

.

.

. E4. Surface settlements due to groundwater rise within 5 f t

of ground surface for various fallback layer thicknesses

. 62

. 62

. 63

. 64

. 65

. 66

. 67

. 68

. 69

. 70

. 73

. 74

. 76

. 80

. 87

. 89

. 91

- ix-

Conversion Factors

British units of measurement used in this report can be converted to metr ic units as follows:

~

Multiply BY To Obtain

inches 2.54 centimeters feet 0.3048 meters cubic feet 0.02832 cubic meters cubic yards 0.764555 cubic meters pounds 0.4535924 kilograms pounds pe r square inch 0.00689476 meganewtons per square meter pounds per cubic foot 16.02 kilograms per cubic meter

a Fahrenheit degrees 51 9 Celsius o r Kelvin degrees foot-pounds 0.1382 55 meter- kilograms

To obtain Celsius (C) temperature readings f rom Fahrenheit (F) readings, use the To obtain Kelvin ( K ) readings, use: K = (5/9)

a following formula: C = (5/9) (F - 32) . (F - 32) + 273.15.

- X -

TECHNICAL REPORT E-73-1 PROJECT TRINIDAQ

EXPLOSIVE EXCAVATION TESTS IN SANDSTONE AND SHALE

Chapter 1. Introduction

GENERAL

This report i s a technical summary of the resul ts of an extensive s e r i e s of excavation experiments conducted in interbedded sandstones and shales near Trinidad, Colorado. The experimental program progressed from single-charge c r a t e r s through row-charge c r a t e r s to multiple row-charge detonations: The individual charge weights were of the order of 1 ton, and a variety of explosives were used. Project Trinidad was conducted by the U. S. Army Corps of Engineers Water- ways Experiment Station Explosive Exca- vation Research Laboratory (EERL). At the t ime of the experiments, in the summer and fall of 1970, the organization was known as The Nuclear Cratering Group

(NCG). The Nuclear Cratering Group was organized in 1962 to engage in a joint venture with the AEC to investigate peaceful excavation applications of nuclear explosives.

BACKGROUND AND OBJECTIVES

All of the ea r ly cratering experiments performed by EERL were designed as chemical-explosive models" of nuclear experiments. As r e sea rch under the joint Atomic Energy Commission-Corps of Engineers program progressed, exca-

1 1

vat ion with large c he mi cal - expl o s i ve charges appeared to have several pcten- tial mer i t s in itself, and the emphas i s i n

the experimental program gradually shifted to investigating the use of more economical explosives and methods of emplacement.

Project Trinidad was a relatively complete program of experimental tests, the objectives of which were to investigate both the fundamentals of cratering and the economic aspects of explosive excavation. The se r i e s culminated in the successful completion of an actual railroad cut for the relocation of the Colorado and Wyo- ming Railroad.

The site was selected because of two factors. The cratering characterist ics of the interbedded sandstones and shales were unknown and would represent a valuable contribution to cratering technology. Also, it is the policy of EERL to c a r r y out i t s research activities a t the locations of approved Corps of Engineers Civil Works projects whenever possible. An earthfill dam on the Purgatoire River is scheduled for construction near the town of Trinidad, and it was believed that some of the information acquired in the cratering experiments might find application to associated projects. This w a s indeed the

case; two additional railway cuts were excavated during the preparation of this report .

-1-

This report covers only the initial experimental work performed a t Trinidad, including the f i r s t railway cut. erable amount of additional cratering ex- perimentation was performed during late 1970 and through 1971. Included in these later experiments were Project Middle Course 1; Project Minimound: and P r o j -

ect Middle Course 11.3 The las t two railway cuts, designated RR2 and RR3, are also the topic of a separate report.

A consid-

4

SCOPE OF PROGRAM

It will be helpful to the reader to briefly outline the scope of the cratering

experiments and associated technical programs covered by this report.

Table 1 shows a summary and sequence of the c'ratering detonations of this project. The A-series consisted of attempts to create emplacement cavities for explosives by means of hole springing. initial results did not warrant employment of this technique for any of the cratering shots, and the results of this s e r i e s have been documented in a separate report.

The

5

The B-series consisted of eight single 1-ton cratering blasts, three using ANFO (ammonium nitrate and fuel oil) and five using an aluminized s lu r ry blasting agent.

Table 1. Summary of Project Trinidad cratering experiments.

Ser ies Number . Craters , charges, and explosive Date

Aa - B B1 -B3

B4-B8 ) J u l y a;t7;ugust Three 1 -ton single-charge c ra t e r s using A N F O

Five 1-ton single-charge c ra t e r s using aluminized

C C1 -C3

c 4 - c 5

C6

D D1

D2

D3

D4

J s lu r ry , Three row-charge c ra t e r s using five t o seven 1 -ton charges of aluminized slurry; simultaneous detonation. Two row-charge c ra t e r s using five 1-ton charges of aluminized slurry; delayed detonation. Two parallel row-charges of five 1-ton charges of aluminized s lu r ry each; both detonated simultaneously. Row-charge c ra t e r through a ridge; nine charges of 200 t o 2000 lb ANFO. Row-charge c ra t e r along sidehill; five 1 -ton charges of slurry. Double row-charge c ra t e r along sidehill; s ix 1-ton and six 2-ton charges of aluminized s lurry. Double row-charge railway cut; twenty 1 -ton and twelve 2-ton charges of aluminized slurry, t ime delay between rows.

September and

October 1970

November 1970

De c e mb e r 1970

a Hole springing experiments performed intermittently throughout project; topic of separate report.

-2 -

These single-charge cratering tes ts were intended to determine optimum burial depths; i.e., to "calibrate" the rock with regard to its crater ing characterist ics, so that subsequent row-charge detonations could be designed. Further, the B-ser ies was to provide a comparison of the c ra - tering effectiveness of the ANFO with the s lur ry , and to provide single-charge a i r - blast and seismic data with which the cor - responding effects of row-charges could be compared.

The six detonations in the C-ser ies consisted of a variety of row-charges. Three rows were a test of row-charge design procedures, two rows tested the consequences of introducing millisecond delays between charges in a row, and the

las t was the simultaneous detonation of two parallel row-charges. Much of the c ra t e r ing information gathe red during these tes ts was of value in designing the next s e r i e s of experiments.

There were four detonations in the final phase of the program-the D-series. These experiments had a more practical aspect to them than the preceding tests. The D-series investigated the feasibility of explosively excavating cuts through varying te r ra in and long side-slopes. The final experiment, D4, was the excavation of a railroad cut 400 ft in length with a delayed, double row of charges.

Seismic measurements (ground motion), airblast observations, and technical photography were an integral part of the

LTC W. E. Vandenberg

TEST MANAGER Adam Remboldt

TECHNICAL DEPUTY Bruce Redpath I

TECH N ICA L SUPPORT

Legend

LLL - Lawrence Livermore Loboratory

EERL AED - Albuquerque Engineer District

WES - Waterways Experiment Station NOAA - National Oceanic and Atmospheric Administration

- Explosive Excavation Research Laborotory

TECHNlCAL PROGRAMS

I I II

SPRING1 NG 'ITE I 1 (EERL) I INVESTIGATIONS

(EERL-AED)

I OPERATIONAL SUPPORT

t EXPLOSIVES ENGR and CONST and OPNS 1 SAFETY (LLL) I ISUPPORT (AlbuquerqueEngr.Dist. ) I I

PUBLIC INF ORMATl O N t SERVICES

t DRILLING (M i le High

Dri l l ing Co.)

OPERATIONS INDUSTRIAL

D SECURITY

MEASUREMENTS MEASUREMENTS

Fig. 1. Organization of Project Trinidad.

-3-

program. The resu l t s of the major technical programs a r e discussed in separate chapt e r s .

The seismic and airblast studies were oriented pr imari ly towards comparisons of effects from the large variety of detonations, ra ther than towards si te calibration and legal documentation, although this facet of the program was also important. quired virtually all of the surrounding s t ruc tures and because they were unoccu- pied, it was actually hoped that some damage would be caused, and therefore several of the close-in s t ruc tures were

Because the Government had ac-

monitored for potential damage resulting from the la rger detonations.

PROJECT ORGANIZATION

The participating agencies and their functional relationship to the project a r e shown in Fig. 1. In EERL experiments, operational support is provided by the Army Engineer District having jurisdic- tion in the geographical a r e a in which experiments a r e conducted. Drilling and explosives services a r e acquired by com- petitive bid.

Chapter 2. Site Description

LOCATION AND TOPOGRAPHY

Project Trinidad w a s located on the highly dissected uplands of the western Great Plains, about 6 mi west of Trinidad, Colorado (Fig. 2). on the west by the majestic Sangre de Cr is to Mountains, on the north by the twin sp i res of the Spanish Peaks, and on the east by the Great Plains, toire River and i ts tr ibutaries have broken the a r e a into a se r i e s of flat- topped mesas bounded by steep-walled, narrow valleys. The test a r e a s were located on the flat benches and gentle sidehills that border the Purgatoire River.

The region is flanked

The Purga-

The entire Trinidad site a r e a was located within the boundary of the Trini- dad Lake Project, a Corps of Engineers Civil Works program under the Albuquer- que District of the Corps of Engineers. The proposed dam will help to develop

-4 -

the Trinidad a r e a as a recreational and agricultural center for southern Colo- rado.

n-J b , 0 1 TRINIDAD - Scale - mi

Experimental areas

Fig. 2. Project Trinidad s i te location.

The regional climate is semiarid, with most of the precipitation occurring in the summer as thundershowers. Winters a r e relatively mild with intermittent heavy snowfalls. Average precipitation is 14 in. while the average temperature is about 51°F. The semiar id climate has given r i s e to a distinctive flora. t r e e s a r e juniper, piPrlon, and scrub oak. Grasses a r e abundant throughout the a rea , and several species of cactus thrive.

a

The dominant

The test a r e a l ies at the center of the once-bustling Trinidad coal field. Coal mining w a s the life-blood of the a r e a until disastrous s t r ikes and f i res gradually closed down the mines. decrease in population has accompanied the decline in coal production. Ruins of once-prosperous mining towns attest to this decline, and the raising of livestock has replaced coal mining a s the most important industry in the area. Allen mine, located in the upper valley of the Purgatoire 30 mi west of Trinidad, is still active. Trinidad, with about 9,000 inhabitants, is the major population cen- t e r of the region.

A significant

Only the

GEOLOGY

The uplands of the Trinidad a rea con- s i s t of sedimentary rocks of Late Creta- ceous to Ear ly Ter t ia ry age. The surface rocks a r e relatively undeformed and dip gently westward forming the Raton basin. The exposed rocks consist of about 5,000 ft of sediments, th ree units of which a r e relevant to the project: the Trinidad sandstone, the Vermejo formation, and the Raton formation. These rocks form the predominant outcrops in the test a rea . Figure 3 is a generalized

a

1000

+ rc

I 0)

0 u v,

-

500

0

Explanation:

Coal

E-;:;i - - _ _ :... ,....,., . (... ..:\ Conglomeratic

sa nds tone

Sandstone

C 0 -E 0 - - E - O

C 0

% Sandy shale

2 +

Carbonaceous shale

Vermejo forma tion

- Trinidad sandstone

- Pierre shale

Fig. 3 . Generalized stratigraphic section of the Trinidad, Vermejo, and Raton formations. .

stratigraphic column of the rocks exposed in the Trinidad area.

The principal structural feature of the Trinidad a rea is the Raton basin, which is a broad, asymmetrical trough trending

-5-

northward. Isolated normal faults a r e scat- t e r ed throughout the area. In the tes t area the beds dip 5 to 8 deg to the northwest.

The cratering experiments of Project Trinidad were carr ied out in the Vermejo formation of Late Cretaceous age. Vermejo formation consists of complexly interbedded grey to black, carbonaceous, coaly, and silty shale; buff, grey, and grey-green arkosic sandstone; grey and dark-grey siltstone; and coal. ding is thin-to-massive. The thinner beds are parallel stratified and parallel laminated, but the thicker beds a r e len- t icular and irregular. The sandstone is composed of very-fine-to-medium-sized grains of quartz, feldspar, mica, and ferromagnesian minerals cemented by clay and calcium carbonate. The sandstone is highly friable and contains c a r - bonized plant remains. mostly nonfissile and has a wide range of sand and carbonaceous content. The coal beds, which a r e interbedded with the shale and siltstone, a r e of bituminous grade and have been extensively mined. Stratigraphic columns taken from the co re holes in the tes t a r e a a r e shown in Appendix A.

The

The bed-

The shale is

.I, -8-

Overburden in the tes t area consists Platy fragments of of very clayey soil.

sandstone and rounded river-run cobbles a r e common in the soil. thicknesses vary from 0 to 15 f t in the tes t area.

Overburden

PRESHOT ENGINEERING PROPERTIES OF SITE MEDIUM

This section presents a summary of the engineering properties of the rock a t

.a, 1-

Figures A3 through A6.

the Project Trinidad site. of the laboratory physical t es t s are presented in Appendix A.

The resul ts

J, ,I.

The unconfined compressive strength of the intact rock ranges from about 450 psi for shale and coal to 8,000 psi for sandstone. The wide range in compressive strengths reflects the different rock types and the presence of fractures in some of the samples.

Water contenl of the rocks at Trinidad ranges from 1.2 to 9.2%. saturation ranges from 58.3 to 99.6, with an average of about 78T0. Porosity values range from 5.3 to 17.0'10, and averages about 10%.

The material at the Trinidad tes t si te has an average in si tu density of 156 lb/

The degree of

-- 3 3 ft (2.5 g /cm ).

Seismic velocities a t the Trinjdad site varied greatly. Overburden and weathered rock velocities ranged from 1,000 to 2,500 feet pe r second (fps), a representative velocity for overburden and weathered rock was 1,250 fps. Interbedded sandstone and shale and thinly bedded sandstone had velocities ranging from 2,500 to 6,000 fps (a represelitative velocity i s 5,000 fps). The massive, unweathered sandstone had a velocity that ranged from 7,000 to 8,500 fps (a representative velocity is 7,500 fps) .

6 The rock quality designation, RQD, was used to determine a qualitative index of the in situ rock mass. the rock as determined by this method was fair-to-poor (RQD's ranged from 39 to 56%).

The quality of

The RQD was developed by Deere and is used as a measure of the in si tu quality of the rock. Specifically,

:I: Tables A 1 through A3.

-6-

the RQD is the percentage of core recov- e r y computed by considering only pieces of core longer than 4 in. Smaller pieces a r e considered to be due to close shearing, jointing, faulting, or weathering in the rock mass and a r e not counted. Core loss, weathered and soft zones, a r e accounted fo r in the determination. RQDvalues ranging from 0 to 50% a r e indicative of apoor quality rock mass having a smal l fraction of the strength and stiffness measured for an intact specimen.

The laboratory tes ts provided another classification based on unconfined compressive strength and modulus of elas- t i ~ i t y . ~ The tes t results a r e plotted in Fig, 4 and indicate the rock to be of weak- to-intermediate strength.

Fig. 4. Engineering classification for intact rock (after Deere and Miller7).

.- wl a

I x 0

CI a,

0

3 3 -0

4- .- .- c wl

- u-

wl -

s

f

t! a, f .- 0 C -0 t!

ti

u) C

c VI

0 t

+ wl

I E

0) .- t

r C

/ Siltstone 0 Shale

I I I l l I I I I I

1 o2 1 o3 1 o4 Unconfined compressive strength - psi

Chapter 3. Crater Measurements

This chapter presents the crater ing information acquired during the B, C and D s e r i e s of detonations, each . s e r i e s being described in sequence. Some comparative informtion on explosives, based on the c ra t e r measurements, is also included in the discussion. A l l c r a t e r measurements were obtained from plots of conven tional survey data, and the volumes of single c r a t e r s a r e based on their c r o s s sections and the CRATER DATA computer code.8 Volumes of row c r a t e r s a r e based on c ross sectional a r e a s measured with a planimeter and the application of Simpson’ s rule.

Preshot and postshot ground surveys were made along two orthongonal lines for the single c ra te rs , and at selected locations along the alinements of the row c ra t e r s .

A postshot aer ia l view of the pr imary tes t area, showing most of the c ra t e r s in Project Trinidad, is shown in Fig. 5. Experiments D1, D2, and D3 were located in another a r e a about a mile away. The c r a t e r s in the blocked-off a r e a s in Fig. 5 were part of separate studies” and a r e not discussed in this report . A preshot topographic map of the same a rea is shown in Ap- pendix A.

-7-

Fig. 5. Aerial view of principal experimental a r e a stowing B ser ies , C ser ies , and the D4 cra te r .

B -SERIES se r i e s were to obtain optimum cra te r dimensions and depths of burst to be used as a design base for the follow-on row- charge experiments, and to compare the cratering effectiveness of ANFO and a

The B-ser ies consisted of eight 1-ton charges detonated at various depths of burst. The principal objectives of this

-a -

metallized slurry. The design approach was to assume that the optimum depth of burial would be near 1.9 ft/E1I3 (where E is the total energy of the explosive in Mcal), and then to bracket this depth. The value of 1.9 f t / M ~ a l l / ~ was based on previous cratering experience. In this manner cratering curves could be developed to determine the optimum depth of

burial. ANFO was used as the explosive in Detonations B1 through B3, and an aluminized ammonium-nitrate s lu r ry was used in Detonations B4 through B8. Table 2 summarizes the charge emplacement conditions.

The explosives were emplaced in 3 -ft diameter holes drilled with the bucket auger shown in Fig. 6. A considerable. amount of auxiliary drilling and blasting was required to break the rock in most of the emplacement holes so that it could be removed with the bucket auger. An air-

operated, track-mounted dril l w a s used for this supplementary drilling.

After the explosives were emplaced, the holes w e r e stemmed with a mixture of dril l cuttings, 3/4-in. aggregate, and water. Except for the two delayed row- charges, primacord initiated by an elec- tric cap at the surface was used to deto- nate the charges. A column of boosters extending the full height of the cratering charge was used in all cases. acter is t ics of the explosives used in the

* various phases of the project a r e shown

The char-

in Table 3. The resul ts of the c r a t e r measure-

ments program for the 1-ton B-ser ies a r e given in Table 4. One of the B-series c r a t e r s is shown in Fig. 7. The apparent radii and the depths of the c ra t e r s a r e plotted against depth of burial in Fig. 8, and the apparent crater volumes are plotted against depth of burial in Fig. 9.

Table 2. B-ser ies cratering charges.

Hole Depth to Charge Depth of burst Depth top of charge height Actual Design Detonation

Detonation Explosive ( f t ) (ft) (ft) (ft) (ft) Date TLme

B1 A N F O ~ 18.1 12.4 5.7 15.2 16.0 13 Aug 71 0900 B2 A N F O 20.7 15.4 5 .3 18 .0 18.0 14 A u g 7 1 1100

B3 ANFO 22.3 17.1 5.2 19.7 20.0 12 Aug 71 0810 B4 A A N S ~ 17.9 13.9 4 .O 15.9 16 13 Aug 7 1 1400

20.4 16.8 3.6 18.6 19 11 Aug 71 1400 (TD-2)

B5 AA NS (TD-2

B6 AANS

B7 AANS

B8 AANS

(TD-2

(TD-2

22.8 19.0 3.8 20.9 21.5 10Aug71 1115

24.3 20.9 3.4 22.6 24.0 12 Aug71 1440

30.0 26.3 3.7 28.1 28.0 11 Aug 71 0835 (TD-2)

~- ~

ANFO" is the commonly used abbreviation for the explosive consisting of ammonium al I

nitrate (94.570) and fuel oil (5.570). bAANS designates an aluminized ammonium nitrate slurry. This slurry explosive

consists primarily of ammonium-nitrate and contains powdered aluminum for greater energy; the explosive was designated T D - 2 by the manufacturer, IRECO Chemicals.

-9-

-

30 1 I I I

- 25 - ... Radius d-#

/@ .f \ c u

I 2 0 - ,..''Q \ - \

v) c .- 0 6 \ v) A Slurry \ - 5 1 5 - \

0, t& \

\ Q ANFO H b - 4 \ 0' *..*@... \

.i @ ' p

E

b 1 0 - ' Depth .-* -.. \

U

.- U

- c

\ \ 5 - - \

0 A

0 5 10 15 20 25 30 Depth of burial - ft

Fig. 6 . Bucket auger used t o emplace charges. Fig. 8. Apparent c r a t e r radii and depths

for B ser ies .

12,000 1 I I I

10,000 - - -

-

- - (per

c3, cc 8,000

a 6,OOb

8 4,000

I E, -

B1 2,000 -

Fig. 7 . Typical 1 -ton single-charge 0- 1 ' ' . I ' 1 '

Depth of burial - ft 16 20 24 crater . 8 12

Cross sections of the apparent c r a t e r s a r e contained in Appendix B. Fig. 9. Volumes of B series apparent

craters. Considering the wide lateral variations in near surface geology that exist at the test area, the data points in Figs. 8 and 9 show remarkably little scatter about the (visual) best-fit curves drawn through the points. The anamalous appearing c ross - over of the c ra t e r radius curves for s lu r ry and ANFO can probably be attributed to almost 10 ft of overburden present

at the location of Detonation B3. Over- burden depths at the other ground zeros did not exceed 4 ft, except for B4 which has 9 ft.

On the basis of Figs. 8 and 9, the following optimum c ra t e r dimensions for

-10-

Table 3 . Characteristics of Project Trinidad explosives.

Detonat iona B ubbleaab Aluminuma velocity energy content Density

Detonation Explosive (g/cm 1 (m/s ec ) ( c al/g ) (70 ) 3

- ANFO' 0.9 4000 4 50 131-B3 1 D1

B4-B8

D4 D2 D3

AANSd(TD-2le 1.35 44 50 8 60 18

AANS ( T D - ~ ) ~ 1.25 4 500 54 0 5 AANS (IR-lO)f 1.25 5450fJg 1130fJg 25

a

bThe bubble energy of an explosive i s considered a u s e f u l indication of the overall All information supplied by manufacturers prior to experiments.

explosive energy; it is more readily measured than shock energy. C Ammonium nitrate and f u e l oil. dAluminized ammonium nitrate slurry. e Manufacturer's designation; formulated for Project Trinidad by IRECO Chemicals

Manufacturer's designation; manufactured by Gulf Chemicals (slurry). (slurry).

gAfter the completion of the experiments, the bubble energy of IR-10 was reported by the manufacturer to be approximately 400 cal/g, and the detonation velocity 4040 m/sec.

1-ton charges were selected for use in future designs :

largest B-ser ies crater formed by 1 ton of each explosive are:

Explosive

TD-2 Radius (ft) ANFO TD-2 ANFO 23.3 20 .o

Radius (ft) 20 23 Depth (ft) 13.0 11.5 Depth (ft) 11 13 Depth of burial (ft) 17 18 So that comparing radii: Volume (ft ) 6000 9000 3

radius TD-2 = k0.3 - 23.2 - 1.16; radius ANFO 20.0

- - - A comparison of the relative cratering

efficiencies of the two explosives, ANFO and the TD-2 slurry, can be made on the basis of the optimum c ra t e r dimensions and volumes. Let us assume that 1 ton

therefore,

k = 1.64.

of the TD-2 explosive is a more effective And comparing c ra t e r depths: cratering explosive than an equal weight of ANFO by a factor "k"; Le., 1 ton of de th TD 2

& = k - - - 11.5 0.3 - 13.0 - 1.13;

TD-2 wi l l produce the same c ra t e r as k tons of ANFO. We also assume that dimensions scale as the charge weight to the 0.3 power. The actual dimensions of the k = 1.5.

the re for e ,

a Table 4. B-ser ies crater dimensions.

Apparent Apparent c r a t e r c r a t e r Lip crest Lip Lip radius, depth, radius, height, radius, Depth

of burst, DOB Ra Da a1 Hal Reb

Detonation (ft) (ft) (ft) (ft) (ft) (ft )

B1 15.2 17 8 .O 2 2 2.5 60 B2 18.0 20 11.5 25 3.8 60 B3 19.7 24 6.5 27 1 35 B4 15.9 23.5 12.8 28 3.1 60 B5 18.6 23.2 13.0 30 3.4 70 B6 20.9 21.5 11.5 29 3.7 70 B7 22.6 20.2 6 .O 32 2.6 60

b B8 28.1 - Cross-sections of the apparent craters a r e presented in Appendix B; a diagram

b - b - b - - b

a

bMound; charge buried too deep t o crater . showing standard c ra t e r nomenclature appears as Fig. B1.

And comparing c r a t e r volumes:

- k = - - 9000 - 1.5. volume TD-2 - volume ANFO 6000

The values of k resulting from the comparisons above indicate that the aluminized TD-2 s l u r r y is about 50% more effective as a cratering explosive than ANFO. the entire C-ser ies (which immediately followed the single-charge experiments described above) and for the D4 railway cut. ANFO was used, however, in the

4 next two railway cuts, RR-2 and RR-3.

The TD-2 explosive was used for

C-SERIES

There were six row-charge detonations in this series: three rows in which the charges were detonated simultaneously, two in which millisecond delays were introduced between charges, and one simultaneously detonated double row.

The three simultaneously detonated rows were designed to test a hypothesis

of row c r a t e r "enhancement." The t e r m enhancement designates the increase in width and depth of a row c r a t e r that occurs when the spacing between charges in a row is progressively reduced. degree of enhancement is simply the ratio of the depth or width of a row c ra t e r to the depth or diameter of the single c r a t e r that would be created by one of the charges in the row buried at optimum

9 depth. Previous cratering experiments in a very weak clay-shale resulted in an empirical formulation of a relationship between enhancement and charge spacing:' The f i r s t three rows, C1 through C3, were to determine whether the same relationship was also valid for relatively stronger rock such as sandstone.

The

The purpose of the two row-charges with the delays between charges, Exper- iments C4 and C5, was to observe the reduction of airblast , ground shock, and c ra t e r s i ze that would result f rom the delays. It was believed that the lessening

-12-

of c ra t e r dimensions might be more than offset by a favorable reduction of the potentially damaging effects of blast and shock, consequently widening the potential for the application of explosive excavation.

In the course of conducting the C- se r i e s , the decision w a s made to excavate explosively a railway cut for the relocation of the Colorado and Wyoming Railroad. The selected excavation was sufficiently wide that a double row of charges would be required. The las t experiment in the C-ser ies , C6, was an attempt to acquire design information about double row-charges.

The explosives were emplaced in the same manner a s in the B-ser ies ; Le., in 3-ft diameter holes drilled with a bucket auger. of the IRECO TD-2 ammonium-nitrate slurry. Holes were stemmed with pit- run gravel, a small amount of dril l cuttings, and water. The simultaneous rows were detonated with primacord, and the two delayed rows used a specially fabri- cated delay-cap assembly, which was embedded in sand a foot o r two above the charges. Charge emplacement data a r e summarized in Table 5.

Each charge was nominally 1-ton

Simultaneous Rows (C l , C2, C3) Rows C1, C2, and C3 were designed

according to the following relationship between enhancement and charge spacing:

e 2 - -* where

e = enhancement of row c ra t e r dimensions relative to dimensions of optimum single c ra t e r

~

-13-

S = charge spacing

a R = optimum single c ra te r radius

Row-charges at a given spacing should be buried more deeply than the optimum single-charge depth of burial by the amount of enhancement. tionship implies that there will be no enhancement at a charge spacing of 1.4 R a'

A s previously mentioned, this formula was developed and tested in a s e r i e s of row crater ing experimentsg in clay shale. Implicit in the derivation of this relationship is the assumption that a charge in a row is about 30% more efficient in c ra t e r - ing than is a single charge; i.e., one charge in a row of charges will eject 3070 more rock than it would if detonated by itself. hancement means that the size of the c r a - t e r can be varied by adjusting the spacing and depth of the charges. For example, a row-charge to excavate a channel with a varying depth of cut can be designed by varying the spacing between charges of

equal size as the depth of the cut varies. The design philosophy for the first

three rows (C1, C2, C3) was to emplace each row at a constant but different charge spacing, and then to compare the ratio of observed row c ra t e r dimensions to those of a single c ra te r . were in accord with the enhancement equation above, then the principles of row-charge design would be f i rmly established.

The above re la -

The concept of row c ra t e r en-

If the results

The charge spacings selected for the three rows were 1.4 RaJ 1.1 RaJ and 0.8 RaJ where R a is the radius of the optimum single c ra te r . These spacings were a rb i t ra r i ly selected to provide a

0 Table 5. C-series charge emplacement. - Charge Hole Depth to Charge Depth of burst

Charge spacing depth top of charge height Actual uesign number (ft) (ft) (ft) ( f t ) ( f t ) ( f t ) Date Time

Detonation

c 1 r i CIA C1B c1c C1D C1E

C2A C2B c2c C2D C2E

C3A C3B c3c C3 D C3E C3F C3G

C4A C4B c4c C4 D C4E

C 5A C 5B c5c C5D C 5E

C6A C 6B C6C C6D C6E

C6A' C6B' C6C' C6D' C6E'

1.4Ra 20.1

c2.0 } 1;;; 19.2

l.lRa 22.0

{25.0 } 20.7 24.7 25.4

l . l R a 22.4

{25.0 } 111% 22.3

22.5

1.1 Ra I: 1 . l R a

22.5 21.7

' * 21.7 22.0 22.6

22.4 22.5 21.8 21.7 I 22.6

16.5 3.4 16.2 3.9 16.2 4 .O 16.3 3.7 15.4 3.8

18.1 4 .O 18.3 3.7 18.6 3.6 18.4 3.5 17.2 3.5

21.6 3.1 20.9 3.9 21.3 4.4 20.6 4.4 20.5 4.4 20.7 4 .O 21.7 3.7

19.4 3 .O 18.8 3.6 19.2 3.1 18.8 3.1 18.9 3.4

18.1 3.6 18.8 3.2 18.4 3..2 18.4 3.5 18.5 4 .O

17.8 4.7 18.1 3.6 17.7 4 .O 17.9 4.1 17.6 5 .O

17.8 4.6 17.8 4.7 17.3 4.5 17.3 4.4 18.2 4.4

18.2 18.2 18.2 18.2 17.3

20.1 20.2 20.4 20.2 19.0

23.2 22.9 23.5 22.8 22.7 22.7 23.6

20.9 20.6 20.8 20.4 20.6

19.9 20.4 20.0 20.2 20.5

20.2 19.9 19.7 20.0 20.1

20.1 20.2 19.6 19.5 20.4

looT 7 8 . 7 Sep 71

1 Oct 71 50-msec delay between

2 Oct 71 25-msec delay between

30 Sep 71 1 sufficiently wide range to produce significant changes in c r a t e r size.

The resul ts of the C-ser ies are contained in Table 6. Cross sections and

,profiles for all the C-ser ies c r a t e r s appear in Appendix B. photograph of Cra t e r C3 that illustrates the s i ze of a typical row crater .

Figure 10 is a

The results of the C1, C2, and C3 detonations are summarized in Fig. 11, which shows the c r a t e r dimensions, expressed in t e r m s of single-crater dimensions, superimposed on the enhancement equation. The agreement between the result and the enhancement predicted by the equation is reasonable. Deviations from

14-

a Table 6. Summary of row c ra t e r dimensions.

Number C h a r g e s p a c i n Average Half-width ( \Va /2 ) Depth (Dar) E n h a n c e m e n t (avg)" ''a1 - - ' I a l

Row c h a r g e s of e ( f t ) ( f t ) dE%Pf ( f t ) Min ( f t ) Avg ( f t ) Max ( f t ) Min ( f t ) I v g ( f t ) Max ( f t ) v ' j a r \la oar

1.04 o . s a 1 .-12 0 .42

20.0 22 .5 25.5 28 .5 13.0 14.1 14 .8 1.13 1 .11 1.08 1.43 0 . 3 0

7 0.8 ' 1 8 23.0 31.7 33.7 34.7 14 .3 18 .9 22.0 1.32 1.47 1.45 1.42 0.41

c 1 5 1.4 32 18.0 21.7 24.0 26.0 10.5 12 .8 15.0 I .o c2 5 1.1 2 5

c 3 1 .35 0 .39 c4 5 1.1 2 5 20.6 24.0 25.4 26.2 8 .5 10.8 12.1 ( 5 0 - m s e c d e l a y )

c5 5 1 .1 2 5 20 .2 20.7 26 .5 32.2 8.6 1 2 . 8 14.6 ( 2 5 - m s e c d e l a y ) 1.32 0 .31

C G i n 1.1 2 5 20.0 (See p r o f i l e s and c r o s s s e c t i o n s ) (double row) - -

a C r a t e r d i m e n s i o n s apply t o t h e l i n e a r s e c t i o n of t h e c r a t e r , as def ined by t h e s h a d e d a r e a in F i g . l3l of Appendlx R. b T h e d i m e n s i o n s of t h e o p t i m u m s i n g l e c r a t e r , as d e r i v e d f r o m t h e B - s e r i e s , a r e R a = 23 ft , Da = 13 f t , and op t imum

DOB = 18 f t . T h e med ian c r a t e r s l o p e angle ( m e a s u r e d a t t h e p r e s h o t g round s u r f a c e ) is 34 deg .

Fig. 10. C3 row c ra t e r .

-

1 . 6 -

- 0 4

2 1.4- a,

al V C

-c K

W

E

0 1.2 -

-

-

1.0 - -

Maximum - Width Minimum

Depth

Fig. 11. Row c ra t e r enhancement vs charge spacing.

the relationship a r e believed attributable to normal scatter. enhancement concept i s valid for all practical purposes, although further experiments may lead to modification o r refinements.

It appears that the

The results of the three simultaneous rows a r e presented in a somewhat different format in Fig. 12 , in which the row crater dimensions have been superimposed on the single-charge cratering curves for the same explosive. the row c ra t e r dimensions should plot along the lines passing through the origin and the peaks of the curves. Although the information is essentially the same a s that shown in Fig. 11, Fig. 1 2 illustrates the reason that the depth of burst of the charges must be increased as the charge spacing is decreased and the c ra t e r becomes larger.

Ideally

It is interesting to note that the C3 cra te r , produced by closely spaced 1-ton charges, is equivalent to what would have been excavated by 3.5-ton charges spaced a t 1.9 Ra. yield increase required for a dimensional increase of 1.46 t imes i s computed:

This is apparent when the

0.3 = 1.46 1

-1 5-

45-

Fig. 12. Single-charge crater ing curves with row-crater dimensions superimposed.

I . I I I I

o R for single charge

D for single charge

a

a

wher Weer is th quivalent yield f the l-ton charges in the C3 row. that:

It follows

'W = 1.46 3*33 21 3.5 tons.

It is implicit in the derivation of the enhancement formula that, for a given rock type, each charge in a row will always excavate the same volume of material regardless of the charge spacing. The unit volume, or cubic feet of apparent c r a t e r per ton of explosive, was determined for each row in the C-ser ies . This unit volume is also compared to the optimum single volume and is tabulated in Table 7. The data in Table 7 for rows C1, C2, and C3 show that row C2 deviated the most f rom the nominal figure of 1.3 for row-charge efficiency relative to that of a single charge. This, however, is not reflected in the c ra t e r dimensions, which agree well with the predicted enhancement.

eq

-

The average volume of apparent c r a t e r 3 for rows C1, C2, and C3 is 11,140 ft /ton

of explosive, and when this is compared

Table 7. Unit volumes for C-ser ies row cra te rs .

Volume per ton/ VolumeJton of explosivea Row (charge spacing) (ft3) single c ra t e r volume

C1 (1.4 Ra) C2 (1.1 Ra) C3 (0.8 Ra) C4 (1.1 Ra)b C5 (1.1 Ra)' C6 (double row) d

11,620 9,425

12,375 8,500 9,690 8,920

1.28 1.04 1.36 0.93 1.06 0.98

F o r l inear portion of c ra te r ; all c r a t e r s excavated with TD-2 explosive. a

b50-msec delay between charges. '25-rnsec delay between charges. dTwo rows at 1.1 Ra, spaced 1.4 Wa/2.

-16-

3 with the 9,100-ft volume of the optimum single c r a t e r formed by TD-2, the average row charge/single charge efficiency is 1.25. There is insufficient data to warrant changing the value of 1.3, currently in use, to the lower value of 1.25. The average value of 11,140 ft /ton for the simultaneous row-charges will be used as a reference in the discussion on the delayed rows that follows.

3

Delayed Row-Charges ((24, C5) The evaluation of a particular explo-

sive excavation project may indicate that ground shock o r airblast constraints would render the project infeasible if all the charges in a row were detonated simultaneously. detonations, C4 and C5, were planned to determine whether the use of millisecond time delays between charges would r e - duce ground shock and airblast effects without significantly reducing the volume of material excavated. ing in these two rows was established a t 1.1 Ra so that the resul ts could be compared to row C2, the corresponding s imult aneousl y de tonat ed row. How ever , because C 2 had what appears to be an anomalously low unit volume, the delayed rows will be compared with the average unit volume fo r all three simultaneously detonated rows.

It was necessary to decide before the

Two of the C -ser ies

The charge spac-

row-charges were emplaced the t ime delays to be used. A-50 msec delay was selected fo r row C4, with the option of delaying the charges in row C5 by either 25 o r 100 msec, the final decision to be based on the appearance of the C4 crater . The reduction of the ground shock gener- a ated by the C4 detonation w a s so signifi-

cant that there was no reason to t r y a longer delay period in C5. Consequently, the 25-msec delay period was chosen for the C5 row.

\ The dimensions o i Cra t e r s C4 and C5

a r e given in Table 5. When these dimensions a r e compared with the dimensions of row C2, it a p p b r s that a delay between charges has almost no effect on c r a t e r width and a significant effect on c r a t e r depth. With the depth of C2 as a r e fe r - ence, a 25-msec delay reduced the depth of C5 to 91"/u, and the 50-msec delay r e - duced the depth of C4 to 7770 of the depth of C2. The c ra t e r s are shallowest a t the end a t which the delay sequence started. A more meaningful analysis can be made by comparing the unit volumes of the delayed rows to the average unit volume of all three simultaneous rows, When

3 the average unit volum-e of 11,140 ft /ton for rows C1, C2, and C3 is taken, the 25-msec delay reduced the volume of apparent c r a t e r pe r ton of explosives to 87% of the average, and the 50-msec delay to 75% of the average. sponding reductions of ground shock and airblast are discussed in la te r chapters.

The co r re -

Double Row-Charge Detonation (C6) The C6 detonation was originally

planned as a single, delayed row. When it became apparent that a double row of charges would be required to achieve the width of n planned railroad cut, a p re - l iminary double-row experiment was believed necessary. the C6 detonation had already been drilled a t a spacing of 1.1 Ra when the decision was made to convert it to a double row, and so the second row was drilled for the same charge spacing.

One of the rows in

-17-

The separation between the two rows was set at 1.5 t imes the half-width (1.5 Wa/2) of a single row. 1.5 was based on observations made in smal le r scale experiments, and was believed to be close to the maximum separation that could be used without creating a ridge along the c ra t e r bottom. half-width of a row with a spacing of 1.1 R formula:

The factor of

The

is predicted with the enhancement a

2 - 1.4 e - m = 1.27

e = 1.13

and Wa/2 = eRa

= 1.13 X 23

2 25 ft.

Therefore, the rows were separated by

1.5 Wa/2 E 39 ft.

A c r o s s section near the middle of C6 is shown in Fig. 13, which shows the p r e shot te r ra in , the charge emplacement, and the actual c r a t e r outline. sections a r e contained in Appendix B. Ideally, C6 would be expected to have an average depth of eDa (1.13 X 13 = 14.7 ft) over the 39 ft wide portion between the rows. From Fig. 13 it is evident that this depth was not achieved and that the c ra t e r was shallower. The shallowest portions of the c ra t e r a r e on the downslope side of the preshot terrain. The average depth of C6 for the a r e a between the rows is 11.5 ft. The shallowest c ros s section has an average depth of 11.0 f t

Additional

and the deepest c ross section an average depth of 14.7 ft. A s shown in Table 6 the average amount of material excavated by each charge was 98% of the optimum single 1-ton c ra te r volume.

A subsequent review of available information on double row detonations indicated that the use of a short time delay between the detonation of the two rows would produce a la rger c ra te r . Several small scale experiments confirmed this, and a time delay was incorporated into l a t e r double row experiments at Trinidad.

D-SERIES

Tests of the D-series were intended to provide an opportunity to experiment with row-charges in nonlevel terrain. Almost all of the previous EERL experience with row charges had been with detonations in predominantly level and flat terrain.

There were several objectives for the D-series experiments. The f i rs t experiment, D1, was designed according to the concept of enhancement to cut a channel with a constant bottom elevation through a ridge-like topography. Two sidehill cuts were attempted, one with a single row of charges (D2) and one with a double row of charges (D3). detonation was a delayed double row to excavate a railroad cut. The pertinent information i s summarized in Table 8.

The final D-series

Single-Row Charge through Varying Ter ra in ( D l )

This shot was a single row of ANFO

a charges designed to cut a channel with a constant bottom elevation through a ridge For design purposes, the deepest portion of the cut w a s assumed to be 15 ft and the

-1 8-

D = 12.6 ft or

C 0 .- c

6290 a) W -

62 60

L

50 0 50 J 100 150

ri 6290 I C 0

0 .- +

- 5 6260 W

100 50 0 50 6290

C6 6260

100 50 0 50 Distance - ft

Fig. 13. Longitudinal profiles, charge layout, and c ross sections of C6 c ra te r .

length was 110 ft . The shot was designed using varying charge weights and constant enhancement; i.e., a constant charge ment. The optimum dimensions, ob-

spacing in t e rms of S/Ra. Figure 14 is a profile view of the

charge layout showing the design depth and the actual c r a t e r bottom along both the centerline and the deepest portion of the c ra te r .

The single c ra t e r dimensions for ANFO were used to design this experi-

served in the B-ser ies , were:

R~ = 20 ft/ton0e3

Da = 11 ft/ton0a3

dob = 17 ft/tonoa3

-1 9-

0 Table 8. Summary of D-series experiments.

Number of Weight of charges explosive

Row-charge (lb) Explos ivea (lb 1 Description

D1 9 (200 ANFO 9,800 Single row to excavate cut

D2 5, 1-ton TD-1 10,000 Single row along side hill. to 2000) through ridge.

D3 IR-10 5, 2-ton 6, 1-ton 32,000 Double row of charges along

side hill. Double row, delayed; railway cut 400 f t long. TD-2 88,000 D4 20, 1-ton

12, 2-ton

Designations defined in Table 3. a

The design was started at the deepest point of the cut, arbi t rar i ly selected to be 15 ft. weights would not exceed 2,000 lb. cause an unenhanced l-ton ANFO charge will excavate a depth of 11 ft, the required amount of enhancement to cut 15 ft with a 1-ton charge is computed:

It was also decided that charge Be-

15 11 e = - = 1.36;

so that the charge spacing to achieve this enhancement can be computed as :

1 4 1 4 S/R = = f- = 0.76. .85 a e

This spacing was rounded to S/Ra = 0.8. The method of computing the weights

and spacings of the remaining charges in the row are documented in Ref . 11. As an example of this design procedure, refer to Fig. 14 and consider the charge immediately to the right of the 2,000-lb charge a t 0+68. The weight and position of this charge was determined by measur- ing the depth of cut a distance 0.8 Ra to the right of the f i r s t charge (i.e., 0.8 X Ra for a 2,000-lb ANFO charge = 0.8 X 20 = 16 ft) . This depth of cut is approx-

imately 12.5 ft. Because we a r e using enhancement of 1.36, this depth can be reduced by this factor in order to compute the charge weight required at this location. We therefore have an effective depth of cut of:

= 9.2 ft,

and the charge weight required, W, can then be found:

2 0 0 0 ~ * ~ - wos3 -- 11 9.2

W = 1120 lb.

This weight w a s rounded to 1,200 lb to be slightly conservative. placed a t a distance from the 2,000-lb charge equal to the average of 0.8 t imes the c ra t e r radii of the two adjacent charges. 1,200-lb charge is:

The charge is then

The c ra t e r radius for a

20 (mye3 -N 17 ft. 2000

The spacing is then 0.8( 20 + 17 )= 15 ft.

6320

631 0

6300

6290

62 80

2 6320

6310

- b 6300

6290

I .- + O

w

632 0

6310

6300

6290

r bottom at center1 ine

Preshot surface at deepest part of crater

reshot surface at centerline

-

-

-

-

0-20 0 &-2 0 0+40 0+60 W80 1 +oo 1+20 1 +40

( a )

-

-

6320

6310

6300

6290 -

. B 2 0 0 0 Ib

40 20 0 20 40 60 80 1 00 Distance - ft

Fig. 14. D1 . c r a t e r preshot terrain, charge layout, c ros s sections, and c ra t e r profile.

The same procedure is followed for The D1 c ra t e r had a maximum depth the remaining charges. A s indicated of 19 ft, and the average depth along the above, this procedure is more fully ex- deepest par t of the c ra t e r was 15.2 ft. plained in Ref. 11. Table 9 contains the The c ross sections in Fig. 14 show that charge emplacement data for Experi- the deepest part of the c ra t e r was offset ment D1. about 10 ft downhill from the centerline.

-21-

Table 9. D1, D2, D3 charge emplacement.

I D1H

Depth t o Hole top of Charge Charge Depth of b u r s t Tempera -

Charge depth cha rge weight height Detonation t u r e Wind number ( f t ) ( f t ) (Ib) ( f t ) ( f t ) (f t) T i m e (MST) Date (deg) (mph) Weather

D2A D2B D2 C D2 D D2 E I

I D3A

D3 B D3 C D3 D D3 E D3 F

D1I

D3A’ D3B’ D3C’ D3 D’ D3E‘ D3F’

15.2 18.4 22.1 24.5 26.0 26.2 22.0 16.5 12.3

22.3 22.2 22.3 22.1 22.0

22.1

22.2 21.5 22.5 22.2 21.7

28.9 29.3 29.5 29.7 29.5 30.2

11.6 15.9 18.4 21 .I 20.1 21.2 18.5 14.9 10.8

13.3 13.5 13.0 13.5 13.1

15.8

16.3 16.2 16.6 16.9 15.7

18.3 19.1 20.5 20.3 18.6 18.6

300 700

1200 1700 2000

2000 1200

500 200

2000 2000 2000 2000 2000

2000

2000 2000 2000 2000 2000

4000 4000 4000 4000 4000 4000

3.6 2 .5 3.7 3.4 5.9 5.0 3.5 1.6 1.5

9 .o 8.7 9.3 8.6 8.9

6 . 3

5.9 5 .3

5.9 5.3 6 .O

10.6 10.2

9 .o 9.4

10.9 11.6

13.4 13.0 17.1 17.5 20.2 20.5 22.8 23.0 23.0 23.5 23.7 23.5 20.2 20.5 15.7 16.0 11.5 11.0

iil% 1 18.0 17.8 17.5

19.5 19.5 18.7

23.6

!il% 25.0 24 .O

24.4

1115 17 Nov70

1030 18 Nov70

1015a 19 Nov 70

51

49

45

5 N E C l e a r

0 C l e a r

0-5E C l e a r

aD3’ delayed 250 m s e c after D3.

The maximum depth beneath the centerline of the charges was about 16 ft, and the average half-width a t the center of the cut was 34 ft . graph of the D1 crater .

Figure 15 is a photo-

A rather surprising result of the D1 detonation is the volume of apparent c r a - t e r that was excavated.

3 the c ra t e r from 0+10 to 0+90 is 47,200 ft . The charge weight distributed over this portion of the c ra t e r was about 8,450 lb,

The volume of

n

so that the unit volume is 11,170 ftJ/ton Fig. 15. D1 crater .

-22 -

of explosive. a factor of two larger than the observed volume of the optimum single c ra t e r excavated by ANFO. not clear. have resulted in more material being ejected than would have occurred in level terrain, and the single ANFO c ra t e r used as a reference may not have been representative. smaller total energy content compared to some of the metallized s lur r ies , ANFO is nevertheless an excellent cratering explosive, especially when cost is considered.

Single Row-Charge along a Sidehill (D2)

This unit volume is nearly

The reason for this i s The sidehill topography may

4, -0-

It appears that despite i t s

The charges for the D2 experiment were emplaced in a row along a sidehill. The D2 experiment did not have a specific design objective. Rather, it was a case of emplacing the charges in a row along a sidehill t o observe the influence of the slope on c r a t e r s ize and shape.

The experiment was originally designed with the assumption that the TD-2 explosive would be used. However, after the emplacement holes had been dr i l led

a t a spacing of 1.4 Ra for TD-2, i t was decided to use the l e s s energetic explosive TD-1 because of a surplus. The bubble energy of TD-1 is 540 cal /g compared to 860 cal /g for the TD-2. When i t is assumed that c r a t e r dimensions vary as the 0.3 power of the bubble energy,' TD-1 should produce a sma l l e r

>: A la t e r experiment in the same area,

Railroad Cut RR3 detonated in September 1971 had a unit volume nearly identical to D1; it was a lso on a sidehill-ridge topography.4

'The total energies of the explosives will be very nearly proportional to their bubble energies.

c r a t e r than one produced with TJ-)-2, and it should be smaller by a factor of:

(540)0'3 - = 0.87. 860

If this factor is valid, then the charge spacing for the TD-1 explosive in the D1 experiment was actually 1.4/0.87 = 1.6 Ra,

and charge emplacement, the deepest profile of the c ra t e r , and selected c ros s sections.

Figure 16 shows the centerline profile

The charges were buried a t a nominal depth of 13 ft, which is a few feet deeper than optimum for this explosive. the same factor 0.87 that w a s used to obtain a c ra t e r radius for TD-1, the optimum depth of burial for l-ton of TD-1 would be 18 X 0.87, o r approximately 15.5 ft. Burial depths in this sloping terrain a r e referred to the nearest f r e e surface rather than the vertical distance between charge and ground surface; in gently sloping terrain there is very little difference.

With

All charges were detonated simultaneously and the appearance of the c ra t e r is

shown in Fig. 17. The profiles in Fig. 16 show some cusping between charges caused by the wide spacing. were about 2 ft higher than the low points in the c ra t e r bottom. depth a t i t s deepest was 7.3 ft (vertical). The unit volume for the D2 c ra t e r was 8,000 ft /ton. Although this figure appears to be low compared to the average value

3 of 11,140 ft /ton realized in rows C1, C2, and C3, i t is in reasonable agreement with what would be expected on the basis of relative explosive energies. assumed that c r a t e r volumes a r e roughly proportional to bubble energies, D2 could

The cusps

The average c ra t e r

3

When it is

-23-

Center1 ine profi I es

Preshot

Profiles through deepest portion

63 00 I I I I 1 I I I I 1 I I 1

0 20 40 60 80 100 120 140

Distance - ft (a )

v

c 0 .- + 6310

W 6300 B al

631 0

6300

All charges are 2000 Ib of TD-1 in 2-ft diameter holes 1::;

6 3 1 0 1 v fl D2C

\\ A6280

7 6300 D2D

I I I 1 I I I I

Distance - ft 20 0 20 40 60 80 100 120

( b )

Fig. 16. Longitudinal profiles and c ross section of D2 crater .

be expected to have a unit volume close to:

That this nominal unit volume was ex- ceeded could be attributed to less fallback into the c ra t e r because of the sloping t e r - rain.

3 540 - X 11,140 = 7,000 ft /ton. 860 The deepest portion of the c ra t e r

-24-

Fig. 1 7 . D2 crater .

is offset about 20 ft downslope from the centerline of the charges, and slumping of the upslope c ra t e r wal l appears to have occurred.

Although the apparent c r a t e r would be only marginal as a potentially useful excavation, there is a large amount of broken rock in the form of fallback that could be excavated and shaped into a useful cut with conventional machinery. The total volume of broken rock probably exceeds the volume of the apparent c r a t e r by a t l eas t a factor of three. tions of explosive excavation in which

machinery would be used to excavate the rock, large charges would be buried deeper than cratering depths to break and "mound" the rock; i.e., no ejection from the c ra t e r would occur. nique has been successfully applied in

2,12 subsequent experiments.

In some applica-

This tech-

Double Row-Charge along a Sidehill (D3)

The pr imary purpose of the D3 experiment was to test the feasibility of excavating a relatively wide c u t along a sidehill by means of two parallel row charges.

Profiles and c ross sections of the D3 cra te r , both preshot and postshot, a r e shown in Fig. 18. charges in each row, the downslope row consisting of 1-ton charges and the upslope row containing 2-ton charges. explosive, which was surplus from another project, was manufactured by Gulf Chemicals and was designated IR-10. It was an ammonium-nitrate base s lu r ry with a reported aluminum content of approximately 25%. The charges were emplaced in 3-ft diameter holes.

There were s ix

The

The IR-10 s lu r ry w a s reported to have a bubble energy of 1,130 cal/g. basis of this value of bubble energy relative to that for TD-2, the following optimum single-crater dimensions were estimated for designing D3:

On the

Ra (ft) Da(ft) DOB (ft) -- 23 13 18 TD-2 (1 ton)

IR-10 (1 ton) 25 14 19.5 IR-10 (2 tons) 31 16 24

The 1-ton charges in the downslope row w e r e spaced a t 1.4 R apart, which is

35 ft. The 2-ton charges in the upslope row were also spaced 35 ft apart, which i s equivalent to 1.13 Ra (i.e., 35/31). A single row of charges at this spacing in level terrain should produce an enhancement of single c r a t e r dimensions of 1.12; consequently, the optimum depth of burst would be 27 f t (i.e., 1.12 X 24) . The 2-ton charges were placed so that they were approximately 27 ft from the assumed t rue c ra t e r boundary produced by the downslope row. buried so that they were also about 27 ft deep.

a

The charges were

The detonation of the row of 2-ton

-2 5-

Centerl ine Centerl ine profi I e through 1 -ton charges 2-ton charges

profi le through Charge s to t i o ns

-35 f t - 6340 -

- -------------e

6300- do ' I 2b do I 20 so I 1 I 1:O I 140 I 1;O 1 k0 2k I 210 6350F,< ~ Uphill charges fired / 75n m c e r after downhill 6340

Lc c 4 6320

C 0 .- c

P al - W

0+70 yaoo I U L WUUU ID

2000 Ib

D3C' 6320

D3C 40 f t

1 +40 6290

6320

6280 !O 140 160

Distance - f t

Fig. 18. Longitudinal profiles and cross sections of D3 cra te r .

charges w a s delayed 250 msec after the detonation of the downslope row.

The D3 experiment also included an attempt to shape the uphill wall of the c ra te r by means of a presplit plane. The

20-ft deep presplit holes were 2.5 in. in diameter, spaced 2 ft apart, and loaded with 0.25 lb of dynamite pe r foot. presplit holes were fired before the main charges and were located along the assumed true c ra t e r boundary.

The

Figure 19 is a photograph of the D3 crater. resembling the D2 c ra te r in appearance.

The c ra t e r is broad and shallow,

c Y

I

B C 0 .- c

al w

Fig. 19. D3 cra te r .

-2 6- '.A

The mound in the middle of the c r a t e r may have been the result of only partial detonation of a charge. curred is simply a matter of speculation: however, the side-on high-speed film of the experiment did show a pronounced low point in the rising mound a t this location.

The apparent c r a t e r volume per ton of explosive, averaged over the l inear portion of the c ra t e r , is 9,040 f t /ton. This unit volume was unexpectedly low in comparison to the average of 11,140 ft /ton realized in the C-ser ies , especially in view of the reported high bubble energy of the explosive. As previously mentioned, the IR-10 explosive was surplus from another project, and it may have deterio- rated during the 6 mo it w a s in storage although there is no test information to substantiate this hypothesis. Further, there is a major discrepancy in the values of bubble energy reported by the manufacturer. The original value of 1,130 cal /g i s in Table 3, and it is this value that w a s used in the design of D3. After the experiment, a much lower value of bubble energy, approximately 400 cal/g, was reported for this explosive. If the lower value is the correct one, then the charges were buried too deeply and spaced too far apart. note that, comparing the volume of the D3 c ra t e r to the average of 11,140 f t /ton excavated by TD-2, the IR-10 would have a bubble energy of roughly 680 cal/g.

That this oc-

3

3

It is interesting to

3

It is possible that the delay time between the two rows was too long and that the interaction of ejecta from the two rows w a s detrimental to cratering efficiency. a The high-speed film of the detonation, taken by a camera aimed along the alinement of the rows, suggested that

the delay t ime probably was too long. The mound from the downhill row may have been too well developed a t the t ime the second row of charges was detonated. The decision was made to use a shorter delay time between the rows of the follow- on D4 experiment.

The depth of the D3 c ra t e r , averaged over the entire l inear portion of the c ra - t e r , was 10.7 ft. The maximum depth was 15.5 ft and the shallowest portion was 5.5 ft deep. bottom is disregarded, then the average depth is about 12.5 ft.

If the mound in the c r a t e r

The presplitting did not result in a smooth, planar face on the upslope wall of the crater , although portions of the presplit holes were visible near the s u r - face. It is believed that the low strength of the rock and slumping prevented the formation of a clean wall. the presplit plane was located at the correct distance from the main charges because there was little or no disturbance of the ground surface beyond their location. It is possible that removal of the fallback would have revealed the exist- ence of a presplit surface a t depth, say 15 f t , but this was not done. There is

still no reason to believe that presplitting cannot be used in conjunction with cratering detonations, but more experimenta- tion is definitely needed.

It appears that

Delayed Double Row-Charge (Kailway Cut, D4)

The D4 experiment" was designed to excavate a 400-ft cut along the realine- ment of the Colorado and Wyoming

Because of additional railway cuts excavated later, the D4 experiment i s also referred to as RR1; i.e., the f i r s t railroad cut.

.L -4-

-27-

Railroad. The t e r r a in in the a r e a of the c u t was varying, with a portion of the cut along a gentle sidehill. the cut ranged from 15 to 20 ft and the required width at subgrade elevation was 46 ft. Conventional excavation of the cut would have required the removal of approximately 13,000 yd of ear th and rock. The location of the cut is shown in Fig. 5.

The explosive a r r a y consisted of two

Design depth of

3

parallel rows of charges. The anticipated c ros s section and a plan view of the charge a r r a y are shown in Fig. 20.

1

The

0 10 n

5 -

0

Or ig i na I ground -

2 required i f 2-ton charges are used 1 - for depths of cut greater than 16 f t - 1 because of their greater spacing. - - - . - - - - (Explosive = TD-2) -

- 1 1 I I 1 I I ' I 1 I I I I I I I I I I I ' 1 . 1

- - I I 1-

Conventional surtace ex ca va t ion

charges

1-4

: *

*

e 2-ton

A Pre-spl i t 1-ton

3-1 l., -91+00

- 92+00

- 93+00

- 94+00

- 95+00

Fig. 20. Anticipated c ros s section and plan view of D4 experiment.

north row consisted of eighteen 1-ton charges and the south row consisted of twelve 2-ton and two 1-ton charges, a total of 32 separate charges and 44 tons of explosive. parallel to the railway centerline but were offset 2 3 ft on both sides of the centerline. rately according to the terrain elevation along i t s alinement. A constant-yield (i. e., varying-enhancement) design w a s u s e d for both rows.

The rows were alined

Each row w a s designed sepa-

In the varying enhancement design method, the spacing (S/Ra) of the charges in a row is varied rather than their weight in o rde r to accommodate varying depths of cut. enhanced c ra t e r depth; i.e. :

depth of cut = eDa = ( 1'4 )112 Da,

The depth of cut is equated to the

S/R, where Da is the depth of the single c r a t e r formed by the selected charge weight. A

Row charge spacing

Chart of charge spacing vs depth of cut for 1- and 2-ton

Fig. 21.

charges of TD-2 s lu r ry in sandstone and shale.

-28-

simple chart can be prepared showing the required charge spacing for a given charge weight and depth of cut. The chart used for designing the D4 cut is shown in Fig. 21. wherever the depth of cut was greater than 16 ft to minimize the number of dril l holes required. the discussion of the C-series, the charges must be buried deeper as they a r e spaced closer together.

Two-ton charges were used

A s mentioned before in

The separation between the rows w a s fixed a t 46 f t along the entire length of the cut. As a consequence of the fixed separation between rows, the row separation expressed in t e rms of the row-crater width varied with the depth of the cut. the deepest portion of the cut the row separation w a s 1.45 t imes the average’” half- width of a single row crater [Le., 1.45 Wa/2 (average)], and a t the shallow- es t portion the separation w a s 1.70 Wa/2 (average). The charge spacing within each row varied from 0.90 Ra to 1.25 Ra.

Table 10 contains a summary of the charge emplacement data for D4. TWO methods w e r e employed for drilling the emplacement holes for the explosive. The northern line of 1-ton holes was drilled using an underreamer.” The procedure consisted of drilling an 18-in. pilot hole and expanding the bottom portion of the hole to 36 in. with expanding a r m s on the drill bit. The southern line of 2-ton holes was drilled to depth with a bucket auger at the full charge-cavity diameter of 30 in.

At

4,

1 1

The holes were loaded by pumping the s lu r ry directly into the 0

emplacement hole from the mixing truck. A delay of approximately 150 msec was introduced between the detonation of the two rows, with the northern (1-ton) row being fired first.

The development of the mound and ejecta i s shown several seconds after detonation in Fig. 22 , and Fig. 23 shows

Fig. 22. D4 detonation.

4, ,I.

By “averaget’ i s meant the mean half- width of the row c ra t e r s formed by the row of 1-ton charges and the row of 2-ton charges .

Fig. 2 3 . D4 c r a t e r viewed from wes t to east along center line of ra i l - road.

-29-

Table 10. D4 charge emplacement summary,

Depth to 9

Hole top of Charge Charge Charge depth charge weight height DOB number Station (ft) (ft ) (tons) (ft 1 (ft)

A. South Line

D4A'

D4B' D4C' D4D' D4E'

D4F' D4 G' D4" D4I'

D4J' D4K ' D4L'

D4M' D 4 N '

91+00 91+27

91+55 91+80

92+05

92+3 1

92+60 92+93 93+28

93+63 93+96 94 +2 9

94 +6 5 95+00

21.3 26.2

29.6 30.3

30.3

28.3

27.2 26.3

26.4

25.9 27.2 26.5 211.2 19.8

18.0 19.8

20.5 20.2

20.2

19.2 18.3 20.1

17.4

14.5 16.7 16.4 12.8 14.0

1 3.3

2 6.4 2 9.1 2 10.1

2 10.1

2 9.1

2 8.9 2 6.2 2 9 .o 2 11.1 2 10.5

2 10.1 2 11.4 1 5.8

19.7

22.0 25.0

25.2

2 5.2

23.7

22.8 23.2 21.9

20.0 21.9

21.4 18.5 16.9

B. North Line

D4A D4B D4C D4D D4E D4F D4G D4H D 4 I D4J D4K D4L D4M D4N D40 D4P D4Q D4R

91+00

91+26

91 +54 91 +78 92+00

92+22 92+47 92+74

93 to3 93+32

93+59

93+83

94i-03

94+22

934-41

94+60 94-t-79

95i-00

20.7

19.0

22.2 22.6 23.1

23.4 21 .o 20.3

20.6 20.1

20.3 23.3

24.2 23.3

23.9

23.6 23.8 22.9

13.9

15.5 18.6

18.7 18.3 17.4

15.4 15.5

15.9

16.4 16.3

18.8 20.6

21 .o 19.4

19.0'

18.0 18.0

1 6.8

1 3.5 1 3.6

1 3.9 1 4.8 1 6 .O 1 5.6 1 4.8 1 4.7

1 3.7

17.3

17.2

20.4 20.6 20.7 20.4 18.2 17.9

18.2

18.2

1 4 .O 18.3

1 4.5 21 .o 1 3.6 22.4

1 2.3 . 22.1

1 4.5 21.6 1 4 -6 21.3 - _ ~

5.8 4.9

-30-

632C

63 OC

62 80

6320

63 00

I= 6280 I

P

c 0 .- -I-

al W 6320

63 00

62 80

6320

6300

62 80

North c

South

2 tons 1 ton

9 1 +80

I

92+60

I

93+40 East 1~

94+20

32 0 2 80 240 2 00 160 120 80 Distance - ft

I I I I I 1

Fig. 24. Cross sections of D4 railway c u t showing comparison between c r a t e r and cut excavated by conventional methods.

the resulting crater . Four c r o s s sec- equivalent to a unit volume of 11,000 ft 3 / tions through the c r a t e r a r e shown in Fig. 24.

ton of explosive. same as the average for the three simultaneous C-se r i e s row c ra t e r s , and indicates that the delayed double row w a s

This value is nearly the

3

rial was ejected by the blast, which is A total volume of 18,000 yd of mate-

@

-31-

very efficient, particularly when compared to the unit volume of only 8,900 ft / ton excavated by the simultaneously detonated double row, C6. way cut.

Chapter 6 contains a description of 3 the postshot work required to trans-

form the D4 c ra t e r into a useful rail-

Chapter 4. Seismic Measurements

This chapter presents a summary of SCOPE the seismic ground motion program. The objectives w e r e to collect and to compare data on the seismic signals generated by the wide variety of cratering detonations in the project. Only a brief analysis of Station (WES). Conjunctive studies of the

peak motions is presented in this chapter; Ref. 13 contains a more detailed treatment of the data.

The bulk of the information was recorded by personnel of the Soils Division of the USAE Waterways Experiment

structural response of the intake tower and surveys of several close-in residential buildings w e r e performed by the f i rm of

Fig. 2 5. Locations of seismic monitoring stations during Project Trinidad.

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John A. Blume and A s s o c i a t e s of San 0

I D1 - - - 2300 9,000 9,000

t w o of w h i c h w e r e at t h e i n t a k e t o w e r . A l l

D2 I. D3

Francisco. A s u p p l e m e n t a l p r o g r a m of recording locations a r e s h o w n in Fig. 2 5

m o n i t o r i n g b u i l d i n g r e s p o n s e w a s carried out by t h e S p e c i a l P r o j e c t s Party of the N a t i o n a l Ocean Survey (Las V e g a s ) during t h e D1, D2, and D3 detonations.12 w o r k w a s p e r f o r m e d at t h e request of t h e

N e v a d a O p e r a t i o n s Off ice of t h e A E C .

and described in T a b l e 11. Several residential buildings in t h e t o w n

of Viola , a p p r o x i m a t e l y 2,500 f t f r o m t h e

main e x p e r i m e n t a l area, w e r e e x t e n s i v e l y

surveyed f o r the d e v e l o p m e n t of n e w

p l a s t e r c r a c k s and t h e w i d e n i n g of existing

T h i s

Initially, f i v e WES recording stations cracks. w e r e e s t a b l i s h e d , t h r e e f o r g r o u n d motion and t w o f o r the s t r u c t u r a l r e s p o n s e of

t h e i n t a k e tower. A l l detonations from B1 t h r o u g h C6 w e r e monitored at t h e s e

f i v e locations. Only t h r e e stations w e r e r e s p e c t to t h e s h o t locations. T h e velocity monitored by W E S d u r i n g t h e D - s e r i e s ,

E a c h W E S recording station consisted of three velocity t r a n s d u c e r s in a triaxial a r ray w i t h t h e h o r i z o n t a l c o m p o n e n t s

oriented radially and transversely w i t h

t r a n s d u c e r s w e r e moving-coil g e o p h o n e s

Table 11. Locations of seismic recorders, P r o j e c t T r i n i d a d .

Distance f r o m s u r f a c e ground z e r o (f t )

5r-1 5r-2 GM-3 (on t o p (on foun-

(200 ft f r o m (in east of ( in intake of intake GM- 1 GM-2 (-5000 f t GM-4 floor of dation

Detonation intake t o w e r ) Viola) S e r i e s B ) S o p r i s ) t o w e r ) t o w e r )

B1 B2 B3

B4 Approx. B 5 B6 B7

B 8

c 1 c 2

c3 Approx. c 4 c 5 C6

3400

3 570 3390 3240 3330 3170

5050 5040 51 60 5090 4940 4840 4850 4740

a I

- Approx . -

15,500 15,500 15,500

15,500

3060 4710 - 2860 4 580 - 2670 4480 2490 4380 - 2310 4290 - 2560 4250 -

- Approx.

‘16,000 16,000 16,000 16,000 16,000 16,000 16,000

16,000

16,000 16,000 16,000 16,000 16,000 16,000 16,000

16,000

‘1 5,500 15,500 15,500 15,500 15,500 15,500 15,500 15,500 15,500 15,500

,15,500 15,500

- - 2600 - - 2850

9,300 9,300 9,550 9,550

D4 I 1800 - I 15,500 15,500

Dashes denote t h a t s ta t ion was not r e c o r d e d , a

-33-

having a natural frequency of 1 Hz and 7070 record signals at and near the intake 0 critical damping. The geophones were tower, and portable recorders were embedded in modeling clay in o rde r to attach them t o the rock o r structure at each location. on direct-write oscillographs. A semi- onation times. The NOAA instrumenta- permanent installation w a s set up to tion, which is described in Ref. 12

used a t the other locations. Radio communication was maintained between each recorder and Project Control at det- The signals w e r e recorded

V I E, I

\

x u 0 al > al V

+ .- -

- .- + L x Y 0 Q) a

10

1

0.1

0.01

0.

I I I I I " l I I I I I 1 I I l l I I I I I l l 1

Single 1-ton charge a t optimum burial depth f

f2.3

C6 - 10 tons

C3 - 7 tons .

Cl,C2,Dl,D2 - 5 tons

C5 - 5 tons, 25-msec delay C4 - 5 tons, 50-msec delay D3 - 6, 12 tons, 250-msec delay \ -*\ *e..

- D4 - 18, 26 tons, 150-msec delay

- -2.0

I I I I 1 1 1 1 I I 1 I I I I I I I I I l l 1 1

1 o2 1 o3 1 o4 1 o5 Distance - ft

Fig. 26. Peak ground motion amplitudes vs distance,

-34-

also consisted of velocity transducers arrayed triaxially.

RESULTS

'The data collected during this program a r e tabulated in Appendix C. have been expressed in terms of zero-to- peak amplitudes, and an attempt has been made to report separately the amplitudes for compressional, shear, and surface waves f o r all events except the B se r ies .

Motions

The peak amplitudes recorded at the ground motion stations a r e presented graphically a s a function of distance in Fig. 26. The straight-line representation of the data on a log-log plot i s equivalent to an inverse power law relationship of the form:

v = K W P R - ~

where

V = peak particle velocity K = a constant

W = charge weight R = distance from the detonation

p and n = empirically determined

exponents.

This is the most common form of equation fo r empirically describing the variables involved, but it is not a physical descrip-

14 tion of attenuation. A number of significant results a r e

apparent f rom an inspection of Fig. 26. It will be noted that the r a t e at which amplitudes attenuate with distance de- c reases a s the total yield of the detonation increases. the relatively greater low frequency content of the siesmic signal with increasing source size; i.e., increasing charge

This i s probably because of

weight, and the fact that attenuation i s proportional to frequency.

The observation that the attenuation of peak amplitudes with distance depends upon total charge weight also means that the apparent weight- scaling of amplitudes will depend on the distance f rom the detonation. about 0.45 at 2,500 f t to about 0.95 a t 15,000 ft. seismic information from Project Trinidad, including the data f rom the Middle Course I1 Series, is the subject of Ref. 13. In this report the peak amplitudes were succes- sively adjusted for weight- scaling and depth of burial until all the data points had a least squares best fit to a straight line on log-log paper. The final best-fit equation through all the data points, which was derived in Ref. 13, is:

The weight scaling varied from

A statistical analysis of all the

0 .74 R-187 v = 3.37 x l o 5 w X exp[0.06 (dob-20) ]

where V = peak particle-velocity, in

cmlsec, W = largest instantaneously deto-

nated charge weight, in tons, R = distance, in ft,

dob = scaled depth of burst, in ft / ton 113 .

This equation can be used to predict peak amplitudes at the Trinidad site within a factor of two for charge weights f rom 1 to 100 tons, and for distances f rom 1 to 10 mi.

The peak particle velocities we're lower than had been predicted before the begin- ning of the test program. preshot predictions were based on previous experience with s imilar charge weights at other sites; however, the observed peak

The initial

-3 5-

amplitudes were lower by a factor of approximately five. be primarily due to the weak and stratified nature of the rock.

This is believed to

A significant result of the seismic program is the marked reduction of ground shock when delays are used between charges in a row. was we l l known from the extensive u s e of delays in quarrying, it was not known whether the technique could be used for l a rge r scale cratering detonations. In- spection of Fig. 26 wi l l show that the delayed five-charge rows generated seismic amplitudes virtually identical to a single 1-ton charge. This is approximately a three-fold reduction of the seismic signal generated by a simultaneously detonated row of five charges. delay t ime of 50 msec appears to have been only slightly more effective in dimin- ishing ground shock than the 25-msec delay; however, the sho r t e r delay was definitely advantageous from the standpoint of c ra t e r ing eff i c ienc y .

Although this effect

The relatively longer

The resul ts of monitoring close-in residential s t ructures was disappointing in the sense that no damage was observed. The peak ground motion amplitude re-

corded at a building was 1.5 cm/sec in Viola, and careful scrutiny of plaster walls failed to disclose any new cracks o r the widening of pre-existing ones.

The response of the intake tower was analyzed by John A. Blume and Associates to establish ground motion cr i ter ia that would avoid detectable damage to the structure.15 reinforced concrete structure about 180 f t high. Its fundamental natural period of oscillation is about 0.6 sec. Because the response of the tower to ground motion depends on the frequency content of the ground motion, and because the spectrum of ground motion depends on both charge weight and distance, it is not possible to state a simple set of c r i te r ia . For a relatively large detonation, say 300 tons, a safe level of ground motion would be about 3.5 cm/sec; however, for smaller charges of the o rde r of 5 tons, the safety cri terion would be 20 to 30 cm/sec of ground motion at the base of the tower. Peak motion recorded at the base of the tower was approximately 0.08 cm/sec, and the maximum motion recorded at the top of the tower w a s about 0.18 cmisec .

The tower is a massive

Chapter 5. Airblast Measurements

SCOPE

The wide variety of cratering experiments in this project provided an excellent opportunity to acquire airblast information usefu l for extending the capability to predict airblast f rom explosive excavation projects in general. the airblast program w a s instrumentation

Another aspect of

of various a reas a s a legal safeguard. Airblast overpressures were measured at ranges of a few hundred feet to several miles from the detonations.

Buried detonations in unsaturated rock give rise to two distinct airblast p r e s s u r e pulses. The initial o r ground-shock- induced pulse i s caused by the upward spa11 velocity of the ground surface above

-3 6-

the explosion. gas-vent-induced pulse when the cavity

This is followed by the

gas vents t o the surrounding atmosphere. strong fo r shallow detonations, but i s rapidly suppressed with increasing scaled depth of burial; it also lags further behind the ground-shock-induced pulse for deeper detonations. Ground shock airblast becomes dominant for deep explosions.

The gas-vent pulse is relatively

The amplitude of either airblast pulse is a function of range from the experiment location, type and weight of explosive, depth of burial, rock type, and the a m - bient atmospheric conditions. Past experience has shown that peak pressure at intermediate distances generally attenuates

, where R is the dis- as R - l . o to R-1.3

tance. Further, it is possible to adjust f o r charge size and for differences in ambient air p re s su re by simple scaling l aws . The remaining factors; Le., depth of burial, medium, and explosive type, are the chief influences on airblast from single-charge explosions that can be examined experimentally . Previous experiments have investigated airblast f rom TNT and nuclear explosives in a variety of soil and rock media.

RESULTS

Because of the volume and complexity of the data collected, only a few selected resul ts of the airblast program a r e p r e - sented in this chapter. A complete summary of the observed peak overpressure is tabulated in Appendix D, and an analysis of this information accompanies the data. Reference 16 i s a thorough analysis of all the airblast data.

Some of the more relevant information is presented graphically in Fig. 27, in which observed peak overpressures for selected events have been plotted against distance. vide a comparison between peak overpres- su res from a variety of detonations. Airblast amplitudes from two 1-ton detonations, Detonation B6 near optimum depth of burial and a 1-ton surface burst, a r e plotted to provide a f rame of reference for the row-charge data. row-charge data a r e f rom a simultaneously detonated five-charge row (Cl ) , f rom a delayed five-charge row (C5), and from the delayed double-row D4 detonation. Except for the surface burst, lines with

-1.2 a slope of R the data points. The overpressures plotted in Fig. 27 a r e those recorded perpendicular to the sides of the rows, these pressures always being higher than those recorded off the ends (axial direction) of the row charges. tion of the data for B6, the peak p res su res plotted w e r e generated by the gas vent.

Figure 27 is intended to pro-

The

have been drawn through

With the excep-

To put the plotted airblast amplitudes into some perspective, Table 12 contains cr i ter ia for damage, a matter of direct interest for explosive excavation projects.

There a r e several significant aspects to the information in Fig. 27. The introduction of delays between the charges in a row substantially reduces the airblast generated, a s is seen by comparing C1 to C5. 44 tons of explosive in D4 generated airblast p u l s e s that were generally lower in amplitude than those generated by a 1-ton surface burst. However, one of the recordings for D4 indicates an overpres- su re that approaches a 1-ton surface

The detonation of the a r r a y of

- 3 7 -

I I I I I I I I

Delayed double row 18 and 26 tons, 150-rnsec delay (D4), I

I I I I I l l 1

Threshold for damage average size windows

-Threshold to large v

5 charge row 25-rnsec

delay (CS), i

1-ton near

for damage Jindows

l l lV l l l , "V ,

L5 charge row (C1 )I

Fig. 27. Peak airblast overpressures for selected Project Trinidad detonations.

Table 12. Airblast damage cr i te r ia . This is pointed out to illustrate the man- ne r in which airblast pulses from a r r a y s of charges can interact, and the fact that

Overpressure, P (mbar) Degree of damage

2 Possible window damage, particularly

3 to large store windows. airblast is, in general, difficult to predict.

windows can be expected.

4.5 Some damage to average size windows for these detonations, although the nearest

Some damage to large plate glass No window pane damage was reported

can be expected.

damage to average wooden doors . 13 Extensive damage to windows; probable buildings w e r e Only 2,500 ft away. Fig-

40 Most small casement wmdows smashed. ure 27 shows that the threshold fo r damage to small windows corresponds to a distance of approximately 1,000 ft f rom a five-

burst. This point is plotted in Fig. 27, charge row such a s C1. A t this distance, and is attributed to reinforcement of the there is probably a greater probability of gas vent pulse f rom one of the two r o w s damage from rock missiles than from by the ground shock pulse from the other. airblast.

Over 40 Structural damage possible.

-38-

Chapter 6. Engineering Studies of ID4 Crater

INTRODUCTION

An intensive postshot investigation of the D4 cra te r (RR1) was conducted to determine the engineering properties of the fallback, and to determine the shaping required to bring the c ra te r to design configuration. The investigations consisted of:

Trenching and weighing a portion of the fallback to determine the m a s s density Applying the point-count technique to determine the particle gradation of the fallback Drilling, coring, and using the borehole camera to locate the limits of the fallback and rupture zones Shaping the c ra te r by bringing the bottom to grade and dressing the slopes Compacting the fallback with a heavy, vibratory compactor to measure induced settlements Testing for the mechanical prop- e r t ies of the material at the University of California Richmond Laboratory. (This portion of the program, reported in Appendix E, consisted of an accurate determination of particle gradation, determining the strength and compressibility characterist ics of the fallback, and ascertaining the validity of modeling a heterogeneous material of this type.)

17

0 ON- SITE INVESTIGATIVE PROGRAMS

Figure 28 shows the location of the field programs in and around the c ra te r .

MASS DENSITY AND BULKING FACTOR

Immediately after the D4 detonation, a trench was excavated in the western po r - tion of the c ra te r to determine the mass density of undisturbed fallback. A re la - tively level area, judged to be representative of the entire crater , was selected for trenching. trenching was guided with care to preclude unnecessary disturbance to the fallback. The material was removed, loaded on 5-ton dump trucks, and weighed. The volume of the material removed was determined by a detailed survey of the resulting trench.

The front-loader used for

The fallback removed from the trench weighed 372,350 lb, and the volume of the

3 trench was 2894.4 ft , resulting in a mass 3 density of 128.6 lb/ft . The bulking

factor’” of the fallback can be computed by comparing this density to that of the undisturbed rock. Laboratory tes t s of the country rock showed an average density of 156.3 lb/ft , thus yielding a bulking factor of 1.22, a value which is consistent with data f rom similar experiments.

3

18

FIELD DETERMINATION OF PARTICLE GRADATION

Because of the large dimensions of the coarse particles of the rubble f rom a cratering explosions, the initial particle gradation was determined by a statistical

,,. The bulking factor is the ratio between

the in situ density of the country rock determined by coring and the mass density of the fallback. It is a valuable parameter in determining the posts hot properties, balancing of cuts and fills, and estimating ear th nd rock moving production rates . 30,21

-3 9-

I ----- Scale - f t

Fig. 28. Map of D4 c r a t e r showing location of postshot engineering investigations.

technique developed by Anderson, l7 based on ea r l i e r work by W01man.~' Because Anderson's technique was originally developed for nuclear detonations, which produce considerably large rock fragments, it w a s necessary to modify his technique. The dimensions of those particles which could be measured w e r e obtained as speci-

The gradation curves obtained at both ends of the railroad cut a r e shown in Appendix E"' where they are compared with carefully sieved samples obtained at the University of California. the field technique a r e considered to be satisfactory and reasonable approxima- tions of the actual grain- size distribution.

Results of

fied by Anderson. In addition, representative samples of the fines w e r e collected, air dried, and sieved in the normal fashion.

DRILLING, CORING, AND BOREHOLE PHOTOGRAPHY

The two methods can be then combined to produce a single curve; the lower limit of the point-count is faired into the upper limit of the sieving.

Continuously cored holes w e r e drilled to establish the l imits of the fallback and rupture zones. Borehole photography w a s used to determine the extent of blast- induced fracturing .

4, -8.

4,

Only those particles below a conveniently measurable size w e r e counted during the >I: sieving. Figure E l .

-40-

0 Three NX core holes were drilled in

6300 -

6280 -

the cratered a rea a s shown in Figs. 28 and 29. Holes 1 and 2 were located at the bottom of the c ra t e r and hole 3 was located on the ayparent c ra te r lip, 100 f t f rom the centerline. The holes were located approximately at mid-crater.

Analysis of the core indicated 7 f t of fallback in Holes 1 and 2, a depth that contrasts with the 2 f t of fallback observed in the west end where the trench was excavated. Further investigations indi - cated 1 to 2 f t of fallback in the low a rea on the east end of the c ra te r . This variation in the thickness of the fallback represents the presence of mounds in the bottom of the c ra te r that appear to be randomly distributed.

The extent of blast -induced fracturing was determined from an examination of the core and from borehole photographs. The rock was highly fractured to depths of 16 to 18 ft below the ground surface at Holes 1 and 2. No blast-induced fracturing could be observed at Hole 3 . Outlining the boundary of blast-induced fracturing shown in Fig. 30 was difficult because of the already fractured and weak nature of the country rock.

SHAPING OF RAILROAD CUT

Earthwork w a s required to shape the c ra t e r into its final design configuration; i.e., ready to accept subbase, ballast, and track. This work consisted of daylighting the ends of the crater , scaling the slopes, and leveling the bottom to subgrade elevation. most of the earthmoving.

of the east end of the crater .

A bulldozer with ripper accomplished

Operations began with the daylighting The loose

Ground surface /

induced fracturing

100 60 20 0 20 60 100

Fig. 29. Location of core holes in D4 c ra t e r and extent of blast- induced fracturing (c ross section through Station 93+00).

Fig. 30. Dozer daylighting end of cut and bringing cut to grade.

material w a s pushed into the c ra t e r and the operation progressed towards the w e s t end of the crater , cutting and filling a s required. A considerable mound of mate- r i a l w a s pushed out the west end of the crater . This operation is shown in Fig. 30. Some ripping was necessary in order to daylight the ends of the c ra te r ; daylighting of the ends was not included in the experiment design.

Three working days w e r e required to daylight the ends and bring the bottom of the c ra t e r to rough subgrade. Two additional days were spent in scaling the slopes and final leveling of the bottom of the cut. A 5-yd 3 front-loader was brought in to

-41-

ass i s t the dozer in scaling the slopes because of the difficulty in negotiating the slopes with a blade ful l of material. slopes were scaled by pushing the material into the c ra t e r and spoiling it with the front loader, a s shown in Fig. 31.

w a s somewhat troublesome because of the steepness of the c r a t e r slopes, large particle sizes, and the amount of rubble in the bottom of the c ra te r . Several hundred cubic yards of material were removed f rom this area alone. the final cut configuration.

The

The a rea in the vicinity of Station 91+60

Figure 32 shows

Total equipment t ime required was 45 dozer - hours and 16 front -loader hours. Equipment time could have been reduced substantially had the c ra t e r been day- lighted by the explosion, in which case it is estimated that the cut could have been shaped in about 3 working days.

FALLBACK COMPACTION AND FIELD SETTLEMENT STUDY

Surveys were made to record any fallback settlement that might occur naturally, or might be induced by a heavy vibratory compactor. Six surface settlement

Fig. 31. Dozer scales crater slopes; front loader removes material from crater.

markers , detailed in Fig, 33, were emplaced in the undisturbed fallback. m a r k e r s w e r e emplaced on the natural mounds and valleys of the c ra t e r bottom in order to observe settlements of different thicknesses of fallback. The locations of the markers are shown in Fig. 34.

18 December 1970, and surveyed again 4 mo la te r on 17 April 1971.

The

These markers w e r e first surveyed on

During the

Fig. 32. Finished cut .

-Reinforced concrete block

Settlement-at-depth marker

Cross section of marker in place

Fig. 33. Settlement markers .

-42-

l 2 f t ~ r ft

f Settlement markers

0 Surface marker 12 ft

Q Depth marker (buried 2-1/2 f t )

*Depth marker (buried 5 f t )

Fig. 34. Layout of settlement markers for vibratory compaction tests.

intervening 4 mo the material was subjected to 14 in. of precipitation; however, comparison of the levels showed negligible settlement during this period.

Vibratory compaction of the dressed cut started after two test panels had been laid out along the centerline, a s shown in Fig. 34. Surface marke r s were placed in hand-excavated holes, and the displaced material was carefully replaced. Settlement -at-depth marke r s were emplaced in 6-in. diameter drilled holes lined with a plastic casing. and air, rather than drilling mud or water, were used to dril l these holes to minimize disturbance of the fallback. It was recog- nized that the vibrations from the dr i l l bit would probably cause some unavoidable settlement in the surrounding medium. 1-in. diameter pipe was embedded in a small quantity of grout at the bottom of the holes, and a concrete collar and steel plate were then placed over the hole. Markers were placed at 2.5 and 5-ft depths. The tops of all markers were

A rock bit

A

surveyed both vertically and horizontally to 0.001 ft.

A smooth-roller vibratory compactor, illustrated in Fig. 35, made 40 passes

-4 3

Fig. 35. Bros smooth-roller vibratory compactor.

over each test panel. Specifications for the BROS Model SPV-730 a r e as follows:

Total weight, lb 20,000

Dynamic force, lb 30,000 Vibration frequency, vpm 1,100-1,500 Drum width, in. 84 Travel speed, mph 0 to 1 2 Total applied force, lb 42,200

The settlement markers were surveyed for vertical displacement after 2, 5, 10, 20, and 40 passes, and for horizontal displacement after the final pass. observed settlement of the surface is plotted against the number of passes in Fig. 36 together with representative curves of the average and the maximum settlements.

No settlement at depth w a s observed. Any apparent movements were well within the l imits of surveying e r r o r . The lack of measurable settlement at depth probably reflects the combined effects of particle gradation, the compaction of the material falling under impact after the explosion, compaction due to the construction equipment shaping the cut, and the inability of a large vibratory compacter

The

4- Lc

I c K Q)

Q)

Q) v,

E - c c

0.

0.

0.

+ 13 !IO, 13, 16

08, 14 04, 9 , 14

0. ' l o 04, 10, 16

I I

0 8 10, 16 16 13 @ 10

13, 14, 16 .9 I \'\ \ \*5, 8

011 012

-----*3, 15 ---------- L O ~ , 6, 15-

0 3 \ 0 7 .? I '\ 02, 6 r X 1 1 17

Fig. 36. Surface settlement produced by vibratory compaction t e s t s .

t o appreciably affect the mater ia l at 2.5- and 5-ft depths.

The compaction portion of the field testing originally included a test in which the mater ia l w a s wetted before compaction. It w a s anticipated that this wetting of the fallback would wash the fines f rom between the la rger particles, and weaken the l a rge r particles, resulting in settle-

ment s imi la r to that observed in rock-fill dams. However, the high percentage of fines and their clay nature negated this portion of the testing. The water did not percolate down through the material, but merely puddled at the surface. The r e su l t s of the laboratory t e s t s reported in Appendix E provide further insight into the wet behavior of this material.

Chapter 7. Conclusions

The single charges detonated in the B-ser ies showed that the optimum depth of burial fo r 1 ton of metallized s lu r ry (TD-2), o r for 1 ton of ANFO, is approximately 18 f t . that the TD-2 s lu r ry is about 50% more effective than AFNO a s a crater ing explosive, The relative inferiority of ANFO, however, w a s not substantiated by the D1 experiment in which the ANFO nearly

This series also indicated

equalled TD-2 in crater ing performance. The reason for the discrepancy between the single- and row-charge resu l t s is not c lear .

The concept of enhancement, which was originally developed in a weakclay shale and which forms the basis for row-charge design, was confirmed for the Trinidad sandstones and shales and can be extended to other rock types with confidence.

-44-

The use of millisecond time delays between the charges in a row offers a promising method of reducing ground shock and airblast without incurring an unacceptable loss of row-charge cratering efficiency. In general, the seismic and airblast amplitudes generated by a delayed row -charge were approximately equivalent to what would be generated by one of the charges in the row detonated by itself. Although the two delay t imes of 25 and 50 msec resulted in about equal reductions of airblast and groundshock, the shor te r delay is definitely preferred because it has the least effect on c ra te r volume. It is tentatively concluded that a delay of 25 m s e ~ / t o n ' / ~ is appropriate for delayed row-charges.

Comparison of the simultaneously detonated double row, C6, and the D4 delayed double row demonstrates that the introduction of a delay t ime between the detonation of parallel row charges in- c r eases cratering performance of a double row. The delay t ime should be of the same order a s the vent time, approximately 150 rnsec/ton113 for charges buried at optimum cratering depth.

sidehill produced relatively broad, shallow craters . The charge spacing was too wide in the D2 single row, and the performance of the explosive and the t ime delay between rows were questionable in the D3 double row. It is now believed that the charges in D3 were buried too deeply and too f a r apart, the consequence of using an incorrect value of explosive bubble energy to design the experiment.

* which is

The single and double rows along a

i: The time at which the explosion gases

under the rising mound of rock a re vented to the atmosphere.

The final experiment, the D4 railway cut, is considered a success in all r e - spects. A subsequent analysis of the direct costs of emplacement drilling, explosives and post shot shaping indicates that the cut was explosively excavated for approximately $36,000. The Government estimate of the cost to accomplish the same amount of work by conventional methods, including presplitting for slope control, was approximately $47,000.

The results of the seismic and airblast programs a r e important contributions to the technology. Measurement of the effects of the single- and multiple-charge detonations makes it much easier to predict these side effects for future detonations.

A number of specific conclusions can be made with regard to the engineering properties of the craters , an important aspect of explosive excavation: These conclusions a re based on investigations of the D4 cra te r .

Cratering detonations in the heterogeneous weak-to- intermediate - strength rock at Trinidad produce rubble wi th a

particle gradation that can be classified a s a poorly graded gravel in the Unified Soil Classification System, and can also be described a s a clayey gravel. mater ia l is fragmented to the extent that necessary earthwork can be accomplished quickly and easily, with a minimum of equipment.

The

The D4 delayed row-charge detonation ejected enough material from the Crater that the thickness of fallback mater ia l susceptible to settlement was reduced significantly. Moreover, there is considerable evidence that the fallback i s favorably compacted by the impact of i ts

-4 5-

deposition. of 70% estimated for the Trinidad fallback in the field is almost a s great a s the relative densities achieved in many engineered fills (see Appendix E). It is concluded that the fallback will not be SUS-

ceptible to large settlements or t o stability problems, and that it will provide a stable subgrade for the railroad.

The value of relative density

The rocks of which the fallback is composed a r e weakened by water, and, a s a result, saturation of the mater ia l would cause settlement and would reduce the angle of internal friction by several degrees. The cohesion of the rubble, the intact horizontal bedding surrounding the cut, the wet and dry angle of internal friction, and the gentle 30-deg side slopes provide adequate assurance of continued slope stability.

The smaller particles of the fallback a r e softer and more highly susceptible to compression when wetted. Conse- quently, the amount of settlement due to wetting cannot be estimated on the basis of t e s t s on small size specimens of model'' mater ia ls . The test resu l t s in 1 1

Appendix E do show, however, that It is possible to determine the angle of internal friction by testing model mater ia ls with grain-size curves parallel to the actual grain-size curve, provided that the specimens were compacted to the relative density of the actual fallback. The inability to estimate settlement f rom the behavior of the modeled mater ia l at Trinidad is valuable documentation of the media d e p e n d e n c y of modeling materials. Higher strength and more homogeneous materials investigated by Marachi et al. 2o show much better

-46-

modeling characteristics.

The rock surrounding the cut was dis- turbed only in the immediate vicinity, wi th

little evidence of an extensive rupture zone. The weak, fractured, and weathered nature of the rock probably accounts for the limited extent of the rupture zone.

Finally, the point-count technique provided a reasonably accurate particle gradation curve (see Appendix E). experience is needed in dealing with fines and their relationship to the coarse fraction of the material.

More

e

Appendix A Drill Hole Locations, Stratigraphy and Lithology,

and Material Properties Data

This appendix contains detailed information about the experimental sites. Figures A 1 and A 2 a r e topographic maps showing the location of all charges in each experiment. The stratigraphic in Table A l .

sections for each ser ies , obtained from the core holes, a r e shown in Figs. A3 through A6, and the laboratory-determined physical properties of the rock a r e given

Fig. A l . Map showing location of core holes for B and C se r i e s and LM railroad cut.

-47-

Fig. A2. Map showing location of emplacement and core holes for Experiments D1, D2, and D3.

6320

6280

Southwest

83

Northeast

6300

L 450 ft

Legend

OVERBURDEN: Clayey roi l with platy fragments of sandstone and river-run cobbles.

SANDSTONE: Fine to medium-grained arkosic sandstone, moderate to highly fractured.

SHALE: Grey to black silty shale, highly fractured.

COAL: Soft bituminous coal, very highly fractured.

Fig. A3. Stratigraphy and lithology of B series.

c y.

I .- 6280 5 al w

6260

d 350 f t

C6C

I -4 Legend

I c4c

L .O:.'"

OVERBURDEN: Clayey soil with platy fragments of sandstone and river-run cobbles.

arkosic sandstone, moderate to highly fractured.

Grey to black silty shale, h ia h I Y fractured .

SANDSTONE: Fine to medium-grained

SHALE: " I

COAL: Soft bituminous coal, very highly fractured.

Fig. A4. Stratigraphy and lithology of C series.

-49-

6320

+ q_

I C 0 .- A

0

w 630C > W -

62 8C

West

D2A D3D

Legend -

East

D1 E

6300

+ rc

I S 0

0 > al

.- +

- w 6280

62 6C

West

D4A

D4B

125 f t L I Legend

East

D4C

- I L 125ft

OVERBURDEN: Clayey soil with platy 260 f t

fragments of sandstone and river run

OVERBURDEN: Clayey soil with platy fragments of sandstone and river-run cobbl es.

SANDSTONE: Fine to medium-grained arkosic sandstone, moderate to highly fractured . SILTSTONE: Grey-green siltstone, highly fractured.

SHALE: Grey to black silty shale, high I y f ra c turecl .

Fig. A5. Stratigraphy and lithology of Experiments D1, D2, and D3.

cobb I es. :::!.:. .:.. :::. SANDSTONE: Fine to medium-grained ..... f

arkosic sandstone, moderate to highly fractured.

SILTSTONE: Grey-green siltstone, high I y fractured ,

SHALE: Grey to black silty shale, h igh I y fractured .

COAL: Soft bituminous coal, very h ig h I y fractured .

Fig. A6. Stratigraphy and lithology of D4 railroad cut .

-50-

Table A l . Results of tes t s of B-ser ies rock cores.

Water Dry Grain Compressive Iioie ijepth rontenta “e’lslty specific Porosity strength of elasticity

number Ut) (% ) (lb/ft3, gravity (70) (ps i ) ( l o 6 psi! 1)escription and r e m a r k s

113 19.1-19.8 3.0

H3 19.8-20.8 3.8 R3 21.0-22.9 3.2

B8 13.2-13.5 5.1

BE 15.8-17.0 2.7 n8 21.5-22.2 4.4

na 24.8-27.2 2.0 BE 27.0-28.4 1.2

150.i 2.70 10.7

151.3 2.70 10.4 156.5 2.70 7.1

149.2 2.70 11.5

156.7 2.71 7.4 146.0 2.70 13.3

106.1 1 .E2 6.6 160.8 2.72 5.3

4563 0.4-1.3

5937h 1.3 1739 0.23

1P33b’C 0.8OC

51 59 1.5

1027b 0.072

1070b 0.23 4 93 0.33

Light gray sandstone with ha i r l ine t o

Light p ray sandstone, f ine grained. Dark g ray si1ty sandbtone, very fined

grained. Tan sil tstone with random crientated

sha le s t r ingers . Free water was observed on the s u r f a c e of the tes t specimen while under compression.

1/16 in. sha le seams .

Liglit g ray sandstone, f ine grained. Gray sandy sil tstone with sha le s e a m s

t o 1 in. wide. Free water was observed on the sur face of the tes t specimen while under compression.

Coal. Gray sandy sil tstone with i r r e g u l a r

s h a l e and coal s e a m s ha i r l ine t o 2 in. wide, and partly open f rac tures . F a i l u r e occurred along a high angle, par t ly open f rac ture .

awater content was determined on fragment- remaining fromi compression tes t . bVaIues f o r unconfined compressive s t rength have been adJusted for height-diameter ra t io pe r ASTM C-42. ‘Ciameter of t e s t specimen was not uniform due t o dril l ing action.

-51-

Table A2. Results of tests of C-series rock cores.

Modulus of elasticity Dry Grain Compressive

Hole Depth content Water density specific Porosi ty strengtha number (ft) (70) (lb/ft3) gravi ty (70) (ps i ) ( l o 6 ps i ) Description and r e m a r k s

c 2 c 2.5 - 3.0 2.6 150.2 2.68 10.2 - - Sandstone, tan, f ractured, thin l aye r of brown clay along factures .

c 2 c 10.9 -12.1 2.1 159.5 2.66 4 .O 6420 3.2 Sandstone, tan, horizontal f r ac tu res at 11.5 ft.

c 2 c 12.1 -12.9 2.6 160.4 2.74 6.2 1 3 7 0 0.38 Sandstone, f ine-grained, gray, par t ly open f rac tures .

c 2 c 13.1 -15.0 2.9 152.9 2.69 8.9 7 2 6 0 0.5-1.3 Siltstone, gray, numerous hair l ine t o 1/8 in. sha le s e a m s from 13.1-13.8 f t .

C 2 C 17.25-18.2 4.3 138.1 2.46 10.1 1 2 9 0 0.14 Top 6 in. t ransi t ion zone f rom coal t o gray s i l ts tone separa ted at 18.1 and 19.35 f t , 1 in. shale band at 18.9- 1 9 .O f t , par t ly open ver t ical fracture f r o m 19.0-19.3 f t , partly open f r ac tu res f rom 19.6-19.9 f t , carbonaceous s t r inge r s f rom 18.1-18.5 f t .

healed ver t ical f r ac tu re f rom 21.7- 22.5 ft.

healed ver t ical f r ac tu re f rom 21.7- 22.5 ft.

hair l ine to 1/16 in.

stone, high angle f rac ture f r o m 21.0- 21.8 f t .

I c 2 c 18.2 -19.9 4.2 150.8 2.69 10.2 1 2 9 0 0.13 Dark gray, highly carbonaceous s i l ts tone,

I

C 2 C 21.7 -22.78 2.8 156.3 2.71 7.6 3 2 6 0 0.75 Dark gray, highly carbonaceous s i l ts tone,

c 4 c 10.34-10.98 2.8 153.6 2.67 7.9 6380 1.6 Sandstone, tan, with i r regular shale s e a m s

C 4 C 21.0 -22.7 2.8 150.9 2.69 10.1 7 3 4 0 0.7-1.2 Transi t ion from tan sandstone t o gray sand-

C 6 C 20.0 -20.72 9.2 78.1 1.50 16.6 - - Coal, f rac tured . C 6 C 21.2 -22.44 2.1 1 5 7 .O 2.72 7.5 63 50 1.0-1.5 Transi t ion f r o m t an sandstone t o gray sand-

Par t ia l ly opened horizontal f r ac tu re stone with i r r egu la r sha le s e a m s up t o 1 in. at 22.0 ft.

~ ~~ -~ ~~ a Values for unconfined compressive s t rength have been adjusted for height-diameter ra t io P e r ASTM C - 4 2 .

Table A3. Results of tests of D-series rock cores. Moduhs Water Gra in

Hole Depth contents specific Poros i ty Ci?%sbVe Of number (ft) (%) (1b/rt3) gravity (%) (psi) (lo6 ps i ) Descr ipt ion and r e m a r k s

D1 E

D3D

W A

W B

W C

3.8- 5.1

5.6- 6.5 9.7-11.3

12.1-13.7

2 1.4- 22 .O 28.6-29.6

11.9-12.8

13.0-14.3 18.7-19.5

21.5-22.5

12.0-12.6

15.5-16.6 21.2-22.0

22.6-24.0

28.1 -28.3

28.3-26.5

32.4-33.1

33.1-33.8

6.0- 6.65

15.3-15.9

18.85-19.5

15.9-15.5 18.9-1 9.7 19.7-20.3

22.3-23.9

2 9.2 -2 9.9

31 2-31.8

32.0-32.7

32.7-33.5

4.1

4.1 5.9

2.8

7.3 4.9

2.1

3.5 3.0

4.6

3.3

5 .o 3.8

2.4

2.7

4.4

6.6

4.3

3.6

3.3

7 .O

2.6 - 2 4

3.8

3.7

2.1

1.9

2.4

144.6

149.4 138.9

150.5

138.7 145.4

155.1

148.4 152.7

148.9

151.9

138.9 151.3

155.4

152.2

148.0

143.5

149.4

154.3

150.5

140.0

152.1 1 5lC3

148.2

-

150.5

158.7

154.2

154.4

2.68

2.66 2.69

2.69

2.71 2.73

2.70

2.65 2.62

2.66

2.63

2.66 2.71

2.65

2.69

2.71

2.71

2.70

2.66

2.64

2.72

2.68 2.68

2.69

-

2.69

2.69

2.67

2.67

14

10 17

11

18 14

8

10 7

1 1

7

16 IO

6

9

12

15

12

6

9

17

9 1 OC - 12

1 1

6

7

7

3608

2947 863

2163

4 60 873

8272

530 1373

1074

3055

3853 2000

6824 C - C -

510

898

C - 4140

739

2780 4958 - 4200

710

2460

7169

4245

0.65

0.41 0.12

0.31

0.13 0.25

2.35

0.24 0.67

0.25

0.50

0.14 1.04

1.6 C - C -

0.09

0.34

C - 2 .o 0.11

0.60 1 *E - 0.76

0.06

0.56

0.77

0.65

Sandstone, light brown, intersecting high

Sandstone, light brown, hard . Sandstone, light brown, 60 deg f r a c t u r e

Sandstone, light gray, changing to light

Shale, light gray, hard. Shale. light gray. hard, approximate 45 deg incipient f r a c t u r e top to bottom.

Sandstone, very light brown, very fine- grained, hard. Very thin l a y e r s of s h a l e a t both ends of sample .

Siltstone, light gray, much-fractured. Siltstone, shaly, light gray, horizontal

separa t ion planes a t 18.9 and 19.1 It. Siltstone. shaly. light gray. hard.

Horizontal sl ickensided f r a c t u r e a t 22.0 ft .

Sandstone, light gray, f ine-grained; numerous horizontal separa t ion planes

Sandstone, light brown, hard . Sandstone. light brown, hard; 60 deg f rac-

t u r e f o r compress ion tes t . Sandstone, fine-grained, light gray, hard; 45 deg f r a c t u r e 23.1-22.8 ft .

Siltstone, light gray, dry, hard; too badly f rac tured f o r compress ion tes t .

Siltstone, shaly. light gray, moist; too badly f rac tured f o r compress ion tes t .

Shale, gray, moist; many thin horizontal separa t ion planes.

Shale, light gray, dry, hard; numerous horizontal separa t ion planes.

Siltstone, gray, hard; very badly f ractured.

Sandstone, light brown, hard ; @-in. sha le s e a m removed f r o m bottom.

Shale, gray. moist; numerous sl ickensided separa t ion planes.

Sandstone, light brown, fine-grained, hard . Sandstone, light brown, h a r d . Sandstone, light brown, hard. Very thin

Sandstone, l ight brown with l ight gray band

angle f r a c t u r e s f rom 3.8-4.5 ft.

f rom 9.7-10.1 ft; 45 deg incipient f rac ture 10.3-10.7 f t .

brown a t 12.8 ft; numerous incipient f r s c t u r e s .

sha le s e a m s a t 19.8 and 19.9 ft.

f r o m 22.5-23.0 ft; horizontal separa t ion planes a t 23.1, 23.4, and 23.6 ft. Com- press ion spec imen taken from 2 3 . 2 - 23.8 ft.

Siltstone. light gray, hard ; f r a c t u r e s a t 29.3, 29.5, and 29.7 ft.

Siltstone. light gray, dry. hard; 45 deg separa t ion plane 31.4-31.7 ft.

Siltstone, light gray, fine-grained. hard ; numerous thin, s h a l e seams . Horizontal separa t ion plane a t 32.7 It.

Sandstone, light gray, fine-grained, hard ; m o r e and th icker l a y e r s of sha le .

aWater content w a s determined on f ragments remaining f r o m compress ion tes t s . bValues for unconfined compress ive s t rength have been adjusted for height-diameter r a t i o p e r ASTM-C 42. 'Not tested.

-53-

Appendix B Crater Profiles and Cross Sections

This appendix contains the c ross sec- through B5. The row c ra t e r s w e r e c r o s s - tions and profiles for all of the B-ser ies and C-ser ies c ra te rs . the meaning of the t e r m s used in standard

sectioned at selected, representative locations and were also profiled along the centerline through the charges.

Figure B1 explains The s u r -

c ra te r nomenclature. Each of the single- vey data a re shown in Figs. B6 through charge c ra t e r s was surveyed along two orthogonal sections, a s shown in Figs. B2

B8. row c ra t e r s a r e shown on the drawings.

The average widths and depths of the

True c r a t e r boundary

Cross s e c t i o n o f s i n q l e - c t i a r q e o r vow c r a t e r

/ \ /

P l a n v i e w o f row c r a t e r

Nomenclature which app l i es on l y t o s i n g l e - charge c r a t e r s

Nomenclature and d e f i n i t i o n s which apply t o b o t h s ing le -cha rge and row c r a t e r s

Ra - Radius of apparent c r a t e r measured a t Hal - Apparent c r a t e r l i p c r e s t h e i g h t above o r i g i n a l ground su r face datum o r i q i n a l ground sur face

Ra, - Radius o f apparent l i p c r e s t

Reb - Radius o f o u t e r boundary o f cont inuous Va

Val - Volume o f apparent l i o

- Volume o f apparent c r a t e r below o r i g i n a l ground sur face

e j e c t a

Da - Maximum depth o f apparent c r a t e r below and normal t o o r i g i n a l ground sur face V t - Volume o f t r u e c r a t e r below o r i g i n a l

ground su r face

Nomenclature which app l i es only t o row c r a t e r s DOB - Depth o f b u r s t

Wa - Width o f apparent l i n e a r c r a t e r measured ZP - Zero P o i n t - e f f e c t i v e cen te r o f explo- s ior i energy a t o r i g i n a l ground su r face datum

Wal - Width o f apparent l i p c r e s t

Web - Width o f o u t e r boundary of cont inuous

Dar - Depth of apparent row c r a t e r

SGZ - Surface Ground Zero ( p o i n t on sur face

NSP - Nearest Sur face P o i n t ( p o i n t on su r face same as SGZ f o r h o r i z o n t a l

v e r t i c a l l y above ZP)

nea res t ZP; sur face)

e j e c t a

Fig. B1. Cra te r nomenclature.

-54-

6300 63301 h I C 0 .- 5 - u

6290 _./

6290 _;j

--_ - 5 1 -- - - -- -- --- - --- ---___---___ ----- -----____

1 --_

S BI DOB = 15.2 ft

(ANFO) Ra = 17.0 ft Da = 8.0 ft

DOB = 18.0 ft (ANFO) Ra = 20.0 ft

Da = 11.5 ft

J

8-2 10 0 10 20 -

Scale - ft Fig. B2. Cross sections of Craters B1 and B2.

-55-

6330 ' 1

S

DOB = 19.7 ft (ANFO) Ra = 24.0 ft

Do = 6.5 f t

63 00 r ----_

. -- -_ .

6300 I C 0 .- L

b > al

W -

6320

6290 1 6l 6290

g B -3

- - _ _

S

- _

DOB = 15.9 ft Ra = 23.5 f t Do = 12.8 f t

1 ri

i

i

@ B -4

10 0 10 20 --:-** Scale - ft

-56-

Fig. B3. Cross sections of Cra t e r s B3 and B4.

N

---- I - - -_ .----------- _--__--.-- ----_ -- -- - --- ----- S

DO8 = H 18.6 ft 6290

Ra =23.2 ft

Do = 13.0 ft

7 6320

8-6

10 0 10 20 Tx=F

Fig. B4. Cross sections of Craters B5 and B6.

-57-

+ Lc

I

631 0

i I

6280

62 80

t L

6270 i

W

- -.

S

'.

R DOB = 22.6 f t

Ro = 20.2 f t

Da = 6.0 f t . ,

E

B -7

@ DOB = 28.1 f t

I sr J

--------- E

W

62 80 El

8-8 10 0 10 20

Scale - ft

Fig. B5. Cross sections of Cra te rs B7 and B8.

-58-

a

a

Wa/2 = 24.0 ft 631 0

6280

c v.

C 0 .- c P ’ 6310P-7--

L East a West i iii 6280

I I l l 1 1 1 1 1 L A 50 0 50

6280 East West

150 1 00 50 0 50 c1

6310Ll I , I z y -,

Wa/2 = 25.5 ft D = 14.1 ft

6300

62 70

c 4

c 0 .- A 6300F -K/ -

West 627OL Ea:t Q - w 1 1 1 I I I I 1 1 1 1 I I

100 50 0 50

&O°F& East 0 West 6270 ,

1 1 1 1 1 I I I 1 1 1 1 1 1

100 50 0 50 Distance -- ft

c2

Fig. B.6. Longitudinal profiles and representative cross sections for Rows C1 and C2.

-59-

wa/2 = 33.7 ft

2 6310,

Dar = 13.9 ft

6 3 ' 0 1 1 - 0

West I I I I I I I ( I " ' " " ' '

100 50 0 50 6270 t -East ,

Fig. B7. Longitudinal profile and representative c ross sections for Row C3.

Wa /2 = 2.5.4 ft D-_ = 10.8 ft

6300

rS0.20 40.15 00 .10 40.05 mO=Delay (sec)

0 50 100 150

6270 L c CL.

I 1 I I I I I I 1 I ! ) I I 1 I I I I

I .- 5 L

West I l l I I I I I I I I I 1 1

100 50 0 50

6 3 0 0 r r L East 0 West 6 2 7 0 1 I I I l I I 1 , I , I I ,

100 50 0 50 c4

Wa/2 = 26.5 ft D = 12.8ft

iz 6270LEaSt El West c 1 , 1 1 1 1 1 1 1 1 1 , ,

50 0 50

Distance - ft c5

Fig. B8. Longitudinal profiles and representative cross sections for Rows C4 and C5.

-61-

Appendix C Seismic Data

This a p p e n d i x tabulates all values tions of the recording stations and of peak particle v e 1 o c i t y recorded the station-shot distances are given in during Project Trinidad. The loca- Chapter 4 .

Table C1. Maximum recorded particle velocities for B-series. (Al l values to be multiplied by l o m 3 . ) -

A N F O AANS ( T D - 2 )

B 1 B2 B3 B4 B 5 B6 B7 B8 Sta t ion componen t

a a - 4.9 - a a 2.4 - GM-1 V e r t i c a l 2.8 3.7 3.4 4.8 5.7 a a 2 .o - Radia l 2.3 1.6 3.2 2.2 3 .O

T r a n s v e r s e 2.3 4.1 4.3 2.2 4.2 - Radia l 120 110 130 120 170 160 140 210

( c m /s e c ( c m /s e c ) ( c m /s e c ) ( c m / s e c ) ( c m /s e c ) ( c m /s e c ) ( c m /s e c ) ( c m /see )

-

GM-2 V e r t i c a l 8 5 7 5 8 5 95 115 100 120 160

T r a n s v e r s e 90 60 90 50 70 100 110 150 GM-3 V e r t i c a l 38 4 1 46 48 63 50 50 68

Radia l 18 20 26 19 27 2 5 20 30 T r a n s v e r s e 24 28 26 2 0 3 7 2 5 24 4 2

a a a a 14 - a a

- - 7.5

8 .O

SR-1 V e r t i c a l 9 .o 4 .O 3 .O 5.6 8 .O

T r a n s v e r s e 9 .o 7 .O 8 .O 4 .O 2.0 -

- Radia l 7 .O 8 . 5 7 .O 9.2 17 -

a a - 4.5 a a 3 .O a a 2.5 - - -

SR-2 V e r t i c a l 2.5 3.3 2.5 3.7 4.8 Radia l 2.4 2.1 3.7 2.5 3.2 T r a n s v e r s e 2.4

- 3.8 3.7 2 .o 4.0 -

aUnre l iab le .

Table C2. Maximum recorded particle velocities for C1, C2, C3. (Al l values t o be multiplied by

C1 C2 c 3

Compressional Shear Surface Compressional Shear Surface Cornpressional Shear Surface Station Coniponent (clii/sec) (crn/sec) (c rn /sec) (crn/sec) icm/sec) icrn/seci icm,iser) icm/secl (cm/sec)

GM-1 v 0.5 7 .0 17 10 8 . 5 16 IS 12 25 R 5.0 6.0 7 .s 5.5 12 8.2 8.5 1 0 10 r 4 .0 11 9.0 3.5 14 10 5.0 12 14

CM-2 v 8 0 100 34 0 120 I so 4 50 230 160 ti60 11 180 400 400. 2 50 310 470 4G0 430 s4 0 r 8 0 270 200 100 400 1 2 0 200 480 210

C M - 3 v 73 8 5 170 7 5 100 150 ‘30 100 225 I{ 6 0 82 8 5 70 70 85 85 55 60 T 25 75 51 0 30 8 5 7 5 20 85 9 5 v a

a 22 25 2 6 a 17 32 3 0, 23 r, 7 :i ti

3 8 10 - 37 0.0 - SR-1 22 R 9.0 - T 5.0 15 18 7 .0 v a a a - 1 s I I - 2 0 a 1% a 16 7 .8

10 7.5 - S R - 2 9.5 -

8.2 - T 5.5 12 u .3 7.5 20 ~1.0 s.0 - 1-1

1 a - 25 7.0

12 12 1 ga 1 4

- -

-62-

Table C3. Maximum recorded particle velocities for C4, C5, C6. (All values to be multiplied by

c4 C5 C6

Compressional Shear Surface Compressional Shear Surface Compressional Shear Surface Station Component (cm/sec) (crn/sec) (crn/sec) (cm/sec) (cm/sec) (cm/sec) (cmlsec) (cm/secl (cm/sec)

CM-1 V R T

GM-2 V R T

Ghl-3 V R T

SR-1 v R T

SR-2 V R T

4.1 2 .o 1.2

40 8 0 40 32 25

8 .o 9.0 3.0 3 .o 2.3 3.8 2.4

1 .8 3.1 3 .O

50 120 140 32 18 15

b

3.1

- -

4.1 2 .o 1.7

150 130 110

47 17 20

7.5 9.0 9 .O

3.4 2.9 1 .a

3.3 2 .o 1.5

a a a

- - - 27 30 10 8.0 3.5 1 .o 2.5 3.9 4 .O

3 .O 6.5 3.3 3.0 3.4 4.1

60 45 35 20 18 25

13 21 I ' b

b -

R .5 - 6.4 b

5.4 -b 5.0 3.7 -

16 16 35 9.0 28 15 7 .O 15 13

2 50 2 50 650 580 520 700 140 700 300 130 160 310 130 130 80 30 100 110 38 - 50

47 44

37 21 17

b

14 2%

2 %

7 .o - 12 - 13 11 -

b

not recorded. bunreliable.

-63-

Table C4. Maximum recorded particle velocities for D ser ies . (All values t o be multiplied by

D1 u2 u3 D4

Compressional Shear Surface Compressional Shear Surface Compress lonal Shear Surface Compressional Shear Surface Station Component (cm/sec) (cm/sec) (crn/sec) (cm/seci (cmisec) (cm/sec) (cm/sec) (cm/sec) (cm/sec) (cm/sec) (cm/sec) (cm/sec)

4 0 4 6 8 .O 92 82 1 6 2 8 60 4 0 25 4 0 20

G M - 1 V 8 . 5 62 54 6.0 8 . 9 3 3 23 7 .o 2 6 22 6 .8 55 4 8 'a

1 8 6 .O 3 .o 51 1 1 - 92 4 6 - R T 3.3

b a G M - 2 V a R

b b b b b b b b 4 0 0 - a 1 5 0 0 - ; 1200

800 1 2 0 0 a

-b a 3 a 1, a a a

a -tl a 600 - - - a - -b - - -b - a - - r - a - b b b a b b b - 4 0 0

a a -b - -b -b 8 7 0 - 3 2 0 - 50 a 4 3 0 -

- -

- G M - 4 V 130 7 0 3 0 0 50 zooa 480 100

- - 700 R 1 0 0 2 8 0 520 70 - I T 50 2 8 0 7 00 4 0 - a

SR-1 V R T

SR-2 V R T

a a a a - 70 - 1 1 0

1 7 5 1 6 0

a a a a 100 100 8 0 1 8 0

60 90

1 2 0 1 0 0 - 60 9 5 - 60 50 -

- - 30 a - 2o a 90

92 18

- 7a 2 0 - 6.0

4 .O - 61 4 8 8 .0 4 5 4 5 7 .O 8 8 8 3 20 2 8 60

20 17 6.0 4 7 1 7 6.0 1 0 3 4 0 1 0 3 7 1 3

7 . 3

5.0 6 .5 27 3 6 7 .O 2 8 3 1 7 .O 7 0 60 1 3 3 3 2 5

aUnreliable. bData not recorded.

Appendix D Airblast Data

The observed peak overpressures for tabulated in the following format: first, the name of the experiment i s given, followed by the charge weight, type of

Project Trinidad a r e summarized in Tables D1 through D4, together with an analysis of the data. The data have been explosive, and depth of burial (DOB, in

Table D1. Close-in airblast observations for Detonations B1 through B8 (single-charges). Altitude = 6200 f t AMSL; ambient pressure = 810 mbar

Data sca led Observed data to 1 ton and 1000 mbar

A P s ( m b a r ) Peak

Explo- DOB Distance, o v e r p r e s s u r e Detonation s i v e (ft) Source R(f t ) A P ( p s i )

B1 (1 ton)

B2 (I ton)

B3 (1 ton)

B4 (1 ton)

B 5 (1 ton)

B6 (1 ton)

B7 (1 ton)

B8 (1 ton)

ANFO

ANFO

ANFO

TD-2

TD-2

TD-2

TD-2

TD-2

15.2

18.0

19.7

15.9

18.6

20.9

22.6

28.1

Ground shock

G a s vent

Ground shock

G a s vent

Ground shock

G a s vent

Ground shock

G a s vent

Ground shock

G a s vent

Ground shock

G a s vent

Ground shock

G a s vent

Ground shock

G a s vent

400 900

2000 400 900

2000 8 50

2000 8 50

2000 230 720

20 20 230 720

2020 3 50

1000 2000 3 50

1000 2000 295 810

1845 295

1845 163 510

1670 163 510

1670 275

1630 275

1630 140 460 835 140 460 83 5

a i 0

0.067a 11.021a II .oo8aa 0.64 11.18 0.076 0.0072 0.00307 11.0 11 9 0.0045 0.04 1 I1 .o 1 0 5 0.004 1 6 0.255 11.082 0.0332 0.044 11.015 0.0063 11.322 0.101 0.0373 11.057 11.021 0.007 0.088 0.0335 0 .O 123 0.0705 0.0260 0.0079 0.0556 0.0262 0.0064 11.04 ? 0.00446 0.074 0.0149 0.0528 0.0190 0.0070 11 .o 1 0 5 0.0046 0 .00 13 3

373.0

1864.0 373 .O

1864.0 792.0

1864.0 792.0

1864.0 214.0 672.0

1883.0 214.0 672.0

326.0 932.1

1864.2 326.0 932.1

275.0 755.0

1720.0 275.0 755.0

1720.0 152.0 475.0

1556.0 152.0 475.0

1556.0 256.0

1520.0 256.0

1520.0 130.5 429.0 778.0 130.5 429.0 778.0

839.0

839.0

1883.0

1864.2

5.71a 1 .7ga 0.75a

54.6 15.3

6.48 0.614 0.262 1.02 0.383 3.49 0.894 0.355

6.98

3.75 1.28 0.537

8.61

21.7

2.83

27.4

3.18 4.815 1.79 0.596 7.50

1.05 6.00 2.215 0.673 4.74 2.23 0.545 3.41?

6.30 1.27 4.50 1.62 0.596 0.895 0.392 0.113

2.85

0.380

0.077 6a 0.0643a 0.0703a 0.742 0.550 0.608 0.0206 0.0246 0.0342 0.03 59 0.0244 0.024 6

0.151 0.192 0.269 0.04 34 0.0523 0.0502 0.317 0.352

0.0459

0.0338

0.298

0.0568 0.0508 0.0708 0.0903 0.0896 0.0278 0.0403 0.0507 0.0220 0.0406 0.041 1 0.0294 ? 0.0279 0.0543 '0.0933 0.0174 0.0261 0.0195 0.00346 0.00631 0.00371

aMay be a p r imacord spike r a t h e r than the t r u e ground-shock-induced peak o v e r p r e s s u r e pulse f rom the detonation.

-65 -

Table D2a. Close-in airblast observations fo r Detonations C1 and C2 (row-charges). Altitude = 6200 f t AMSL; ambient pressure = 810 mbar

Data s c a l e d t o 1 ton and 1000 m b a r O b s e r v e d d a t a

A P s ( m b a r )

P e a k Di s t ance , o v e r p r e s s u r e ,

Detonat ion S o u r c e A z i m u t h R( f t ) A P ( p s i )

c1 Ground shock

( f ive 1 - ton c h a r g e s of TD-2 b u r i e d at 18 ft, s p a c e d at Gas vent 32 f t )

c 2 G r o u n d shock

( f ive 1 - t o n c h a r g e s of T D - 2 b u r i e d

s p a c e d a t 2 5 f t )

at 20.4 ft, Gas vent

3 92 1525 3360

/ I b 3 02

la

1000 3171

3 92 1 1525

3360

302 1000 3171 400

1 1515 3360

500 1350 2985

400

II

I /

1 1515 3360

500 1350 2985

1 1

0.128 0.0134 0.00842 0.093 0 . o q - 0.181 0.02 9 0.0164

0.152 0.05E

0.137 0.013J

0.03 9

-

-

e.01g -

0.093 0.0132

0.039 0 .01&5

-

-

365.0 1420.0 3130.0

281.0 932.1

2958.0

365.0 1420.0 3130.0

281.0 932.1

2958.0 373.0

1412.0 3130.0

466.0 1259.0 2780.0

373.0 1412.0 3130.0

466.0 1259.0 2780.0

10.90 1.14 0.718 7.92 2.30 -

15.4 2.48 1.397

12.95 4.35

11.67

-

1.116

3.32 0.852

7.92 1.21

3.32 0.98

-

-

-

-

0.144 0.077 0.125 0.0765 0.0941 -

0.204 0.168 0.244 0.125 0.178

0.159 0.075

0.0592 0.0499

0.108 0.08 14

-

-

-

-

0.0592 0.0574 -

al - p e r p e n d i c u l a r t o a l ignmen t of r o w .

b l l - p a r a l l e l t o and off t h e end of t h e row. ‘ T r a n s m i t t e r d r i f t .

d R e c o r d no i sy .

e R e c o r d l o s t .

feet). For row-charge events, the row configuration, spacing and delays (if any) between charges in the row, number’of charges, and charge weight are also specified. The next column identifies the source of the airblast pulse (ground- shock- induced o r gas-vent- induced). Next, for row-charge events only, the direction in which the airblast pulse was measured is given [perpendicular to row axis (1 ) o r off the end of the row ( 1 1 )].

The succeeding two columns l i s t the distance R (in feet) from the detonation to a given observed peak overpressure A P (in psi), A P in this case referr ing to

peak excess above the local ambient pressure. Most of the measured over- p re s su res a r e average values from two separate gages at the same location. Both the ground-shock and gas-vent peak overpressures are listed (in successive sections of the table) where available. Overpressures for all row-charge detonations were measured in at least two different directions, perpendicular to’the row (I to row) and off the end of the row (11 to row). have measurements along three directions: perpendicular t o the row, of the start ing end ( / Is) , and off the final end ( \ I F ) of the

The delayed row-charges

-66-

Table D2b. Close-in airblast observations for Detonations C3 and C4 (row-charges). Altitude = 6200 f t AMSL; ambient pressure = 810 mbar

Data sca l ed t o 1 ton and 1000 m b a r - O b s e r v e d da ta

f

Peak Distance, o v e r p r e s s u r e ,

Detonation S o u r c e Azimuth R(ft) A P ( p s i )

c 3 Ground shock

( seven 1-ton c h a r g e s of TD-2 bu r i ed at 23.5 f t , spaced at 18 f t ) G a s vent

c 4 Ground shock

(five I - ton c h a r g e s of TD-2 bu r i ed at 20.4 ft, suaced at 25 ft, 0.05-sec Gas vent de lay be tween c h a r g e s )

1

ll

1

II

1

b 1's

'IF"

1's l l F C

1

b

349 1530 3360

461

1160

2791

34 9 1530 3360 461

1160 2791

318 1525 500

2610

1005 3000 318

1525 500

2610 1005 3000

0.105 0.0175 0.0079

0.03 9/0.O 63a

0.0124/0.02Ia

0.0048/0.0067a

0.052 0.0133 0.004!3 0.029 1 0.0114 0.004 !j ?

0.032 0.0052 0.023 0.003 ]I 0.0lg;l - 0.104 0.0212 0.0630 0.0129 0.03%) -

325.0 1425.0 3130.0

430.0

1080.0

2600.0

325.0 1425.0 3130.0

430.0 1080.0 2600.0

296.0 1420.0 466.0

2430.0 936.5

2800.0 296.0

1420.0 466.0

2430.0 936.5

2800.0

8.94 1.49 0.673

3.32 f5.37a

1.057/1.7ga

0.4 0 9 10.57 1 a

4.43 1.133 0.418 2.480 0.971 0.383 ?

2.73 0.443 1.96 0.264 0.912

8.86 1.806 5.36 1 .IO 3.40

-

-

0.103 0.101 0.117 0.0536i 0.0866 0.05169

0.0873 0.0572k 0.0798

0.051 0.077 0.073 0.040 0.0474 0.053 6 ?

0.0282 0.0299 0.0349 0.0340 0.0375

0.0914 0.122 0.0954 0.142 0.140

-

- aTwo va lues given b e c a u s e s igna l showed double peak. b l l ~ = off end of r o w at which de lay sequence began; i.e., s t a r t i n g end.

/ / = off end of r o w a t which de lay sequence ended; i.e., f inal end of two va lues given because s igna l showed C

d o u b g peak.

d ~ o s igna l .

row. F o r the simultaneously detonated Row D1, measurements were made perpendicular to the row uphill (1 ), U perpendicular t o the row downhill (ID), and off one end of the row.

In order to eliminate dependence on charge weight and the effects of local ambient pressure, ranges and overpressures must be scaled to a consistent system. In this instance, all data a r e scaled to a yield of 1 ton and an ambient p re s su re of 1,000 mbar. The conversion to scaled points (Rs, AP,) is given by:

1000 Pg AP, = A P

where Po = ambient pressure (mbar) and W = charge weight (tons). Using Po = 810 mbar and W = total charge weight (or mean individual charge weight €or row events), all the observed data points (R, A P ) w e r e scaled to (Rs, APs) . The scaled values for each experiment a r e also compiled in Table D1, with the

Table D2c. Close-i irblast observations for Detonations C 5 a rges). Altitude = 6200 ft AMSL; ambient pressure = 810 mbar

Data s c a l e d O b s e r v e d d a t a t o 1 ton and 1000 m b a r

P e a k

Detonat ion S o u r c e A z i m u t h RVt ) A P ( p s i ) ‘~(3) A P s ( m b a r ) f Dis tance , o v e r p r e s s u r e ,

c 5 G r o u n d shock

(f ive 1- ton c h a r g e s of TD-2 b u r i e d at 20.4 ft, s p a c e d at 2 5 ft, G a s vent 0 .025-sec d e l a y b e t w e e n c h a r g e s )

C6 G r o u n d shock

( two p a r a l l e l r o w s of f ive 1- ton c h a r g e s of TD-2, 39-ft s e p a r a t i o n b e t w e e n r o w s ; c h a r g e s b u r i e d at 20.4 f t , s p a c e d a t 25 f t )

G a s ven t

L

1‘s

‘IF

L

“ S

“ F

L

/I

L

/I

4 00 1535

500 2430

595 1185

400 1535

500

2430

595 1185

4 8 5 1110 2720

428 1690 3700

485 1110

27 20

428

1690

3700

0.024 0.0070

0.0183 0.0054

0.044 0.0258

0.047 0.014

0.034610 .02ga

0.008 9 /O .007Za

0.042 0.0274

0 .160? 0.04 1 0.0203

0.080+ 0.0211 0.0092 0.3 0 6 ?ba

0 .09 8 /O .O 51

0.048 /0.02Pa

0.14 7 10.1 5Za

0 .0328/0.0476a

0.0 1 5 8 /O .O 2 03 a

373.0 1430.0

466.0 2263.0

554.0 1105.0

373.0 1430.0

466.0

2263.0

554.0 1105.0

452.0 1035.0 2534.0

399.0 1575.0 3450.0

452 .0 1035.0

2 534 .O

399.0

1575.0

3450.0

2.044 0.596

1.56 0.46

3 .75 2.20 4 .OO 1.193

2.95/2.47a

0.7 58 10. 6 14 a

3.58 2.335

13.63 3.40 1.73

6.82 1 .SO 0.7 84 26?b

4.0!3/2.39a

8.35/4.35a

12.511 3 .Oa

2.7 9 14.0 5a

1.35/1.73a

0.0279 0.0408 0.0278 0.0544

0.082 0.110

0.0546 0.0816

0.05259 0.0439 0.0897k 0.0727

0.0784 0.117

0.234 0.162 0.235

0.100 0.138 0.1 54 0.45?b 0.3871 0.201 0.556A 0.325

0.1841 0.191 0.2149 0.3 11 0 .265i 0.340

T w o v a l u e s g iven b e c a u s e s i g n a l showed double peak . a

b L a r g e r of two p e a k s ; c a l i b r a t i o n uns t ab le , va lue unce r t a in .

scaled overpressures A P s expressed in mbar (1.0 psi = 69 mbar).

Using the scaled data, it i s possible t o compare airblast f rom experiments with different explosives o r at different depths of burial. A convenient means of accomplishing this comparison is the relating of all airblast data to an arbi t rary standard. parison is a straight line of slope Rs in a log-log plot of A P s vs An arbi t rary R8Is2 line i s chosen through the point (Rs = 900 ft/t0n1I3, A P ,

One useful standard for com- -1.2

= 25.5 mbar). sures are related to this standard line by a transmission factor, f :

A l l measured overpres-

Measured APs(at R s ) f(at Rs) = Standard line A P s ( at Rs)

Separate values of f a r e assigned to the phenomenon of ground-shock-induced airblast (f

gs from gas venting (f ).

) and the airblast resulting

gv The transmission factor will be a

function of R,, scaled depth of burial,

-68-

a Table D3. Close-in airblast observations for Detonations D1 through D3 (row-charges). Altitude = 6200 f t AMSL; ambient pressure = 810 mbar

Data scaled to 1 ton and 1000 mbar Observed data

f

Peak: Distance, overpr e m ure ,

Detonation Source Azimuth R(ft) AP(psi)

D1 Ground shock

(nine charges of A N F 0, charge size 200 lb to 2000 lb,

average Gas vent 1090 lb, mean depth of burial c 23.9 ft/tonlP, mean spaci g 15.9 ft/ton1/5 )'

D2 Ground shock (five 1-ton charges of TD- 1, buried at 17.7 ft, spaced at Gas vent 32 ft)

D3 Ground c-ock (two-paral-

rows, (I-ton row) each six charges of IR10; downhill row: 1- Gas vent ton charges buried at (1-ton row) 19.1 ft, spaced at 35 f t )

2-ton charges (2-ton POW) buried at 24.4 f t , spaced at 3 5 ft, 40-ft separa-Gas vent tion and (2-ton row) 0.2 5-sec delay between the two rows)

(uphi11 "Ow: Ground shock

ha b

I D

II

U

D

1

1

I1 1

I1

1

II

1

II

1

It

1

I1

1

I1

a 43 1482

770 1900

700 3280

a43 1482

770 1900

700 3 280 1000 3210

1020 2240 3740 1000 3210

1020 2240 3740

1000 3210

720 2220 3815

1000 3210

720 2220 3815

1000 3210

720 2220 3815

1000 3210

720 2220 3815

0.084 0.0227

0.076

0.0232 0.0048 0.005 0.0013

0.002 0,001 0.0047 0.0013 0.0606 0.0196

0.0460 0.0170

0.179 0.0411 0.0350 0.0135

0.05 0.0156 0.0195 0.0067 0.00328

0.0653 0.0210

0.0526 0.0185

ti

0.0128

0.0128

0.00884

0.0088 - -

0.044 1 0.186 o .00938

0.0579 0.0235

0.0203 0.01035

o .04 98

962.0 1690.0

2170.0 799.0

2740.0 962.0

1690.0

2170.0 799.0

3740.0 932.1

2990.0

951.0 2090.0 3490.0

932.1 2990.0

951 .O 2090.0 3490.0

932.1 2990.0

671.0 2070.0 3555.0

932.1 2990.0

67 1 .O 2070.0 3555.0

740.0 2375.0

533 .O 1643 .O

740.0 2375.0

533.0 1643 .O

878.0

878.0

2820.0

2820.0

7.16 1.93 5

1.09 1.976 0.409

0.426 0.111 0.170 0.085

0.401 0.111 5.16 1.68

3.92 1.45 1.09

15.25 3.50

1.15 0.753 4.26 1.33

1.66 0.571 0.279

5.56 1.79

1.576 0.750

6.48

2 .Sa

4.48

d - - 3.76

0.799

4.93 2 .oo 4.24 1.73

1.585

0.882

0.303 0.161 0.246 0.123 0.0672 0.0886

0.0181 0.0093

0.0065 0.0096

0.0136 0.0240 0.211 0.278

0.1 64 0.1 56 0.217 0.624 0.579 0.125 0.124 0.150

0.174 0.220

0.046 0.061 0 .O 57

0.296

0.123 0.168 0.153

d

0.228

- - 0.0785 0.128 0.123

0.153 0.251

0.0885 0.139 0.136

alu - perpendicular to row, uphill side. blD - perpendicular to row, downhill side.

Weighted by individual charge yields to overemphasize the larger charges; this weighting has almost no C

effect on the data reduction. Weighting not normally used in prediction procedures. 'Tlnidentifiable; coincides with f i r s t negative phase from 1 -ton row. a

-69-

Table D4. Close-in airblast observations for Detonation D4 (row-charges). Altitude = 6200 f t AMSL; ambient pressure = 810 mbar

Data scaled t o 1 ton and 1000 m b a r

Detonation Source Azimuth Distance, R(ft) overpressure , AP(ps i ) '~(5) Ps(mbar)

Observed data Peak

ma Ground shock (1-ton row)

Gas vent (1 -ton row)

Ground shock (2-ton row)

G a s vent (2-ton row)

Unidentified 3 r d peakf

4th peakf

5th peakf

6th peakf

775 lb 2,168

1,060 560

3,800 11,750

1 1

775 l b 2.168

l j060 560

/I 3,800 11,750

77 5 l b 2,168

1,060 775

l b 2,168 1.060

I /

560 3,800

11,750 560

3,800 11,750

560 3,800

11,750 560

3,800 11,750

0.140 0.097 0.097 0.106' 0.0049 0.00196 0.123d 0.0616d

0.114' 0.01 1 5' 0.00429 0.123d 0.0616d 0.139 0.1 69 0.131 0.33tie 0.143' 0.0088 0.00361 0.060' 0.0085c 0.00315 0.124' 0.0187 0.00795 0.115' 0.0232' 0.0101

-

722 11.9 2020 8.25

988 8.24 522 9.04

3 540 0.417 10950 0.1 67

722 10.5 2020 5.25

988 - e

522 9.7 3 540 0.98

10950 0.365 587 10.5

1643 5.25 803 11.8 587 14.4

1643 11.2 803e 28.6e

aThe D4 detonation was a double row of charges, emplaced along the contour of a gentle slope. The downhill row (1-ton row) consisted of 18 charges, each of 1-ton yield. (2-ton row) consisted of 14 charges, 12 f 2-ton and 2 of 1-ton yield. The spacing between rows was 46 ft (approximately 41 f t / tonlb) . The 1-ton row was detonated approximately 150 msec before the 2-ton row.

The uphill row

Mean yield of 1-ton row Total yield of 1-ton row Mean DOBg of I-ton row Mean spacing of charges in 1-ton row = 35 f t / tonlb Mean yield of 2-ton row = 1.86 ton Total yield of 2-ton r o w = 26.0 tons Mean DOBg of 2-ton row . = 17.9 f t p o n l P Mean spacing of 2-ton r o w = 28.5 f t / t ~ n l / ~

The measured values a t a given range along these two

= 1.0 ton = 18.0 tons = 19.7 ft/tO 113

bPerpendicular ove rp res su res include values measured along both perpendiculars (c loser t o the 1-ton row, and c l o s e r to t h e 2-ton row). direct ions differ by about 30% in some cases, due to par t ia l and var iable overlap between pulses contributed by the two rows. forcement factors cannot be determined.

The var ious contributions are usually inseparable and prec ise re in-

'Adjusted values -overpressure or pulse identification may be uncertain. dGas-vent pulse f o r 1-ton row overlaps ground-shock pulse for 2-ton row in this direction. eGas-vent pulses f o r both rows coincide at this station; scaled values are scaled on the bas i s

of "2-ton row" alone. The waveforms of the pulses observed off the end of the rows were complex, consisting of

multiple peaks whose re la t ive amplitudes and attenuation r a t e s var ied significantly. peaks were observed; the third, fourth, fifth, and sixth peaks could not be assigned to any specif ic source, due to the g r e a t length and the t i m e delay of the two rows with resul tant over lap and var iable reinforcement between var ious pulses. at all ranges off the end of the rows. determined due to the fact that t h e s o u r c e s of the dominant pulses a r e not always identifiable.

The charges in the 1-ton r o w were emFlaced in under reamed holes, and had a height-to-diameter ra t io of about 1.0. the 2-ton row were not underreamed, and the charges had a height-to-diameter ra t io of about 4 to 1. Thus, the upper portions of the 2-ton c h a r g e s were qui te close to the ground surface, and these charges probably vented a t r a t h e r e a r l y t i m e (causing high gas-vent o v e r p r e s s u r e s f rom the 2-ton row).

Six dis t inct

The fifth and sixth peaks w e r e apparently dominant N o sca led dis tances o r reinforcment fac tors could b e

gAll depths are measured t o the center of the charges. The holes f o r

These charges were approximately 10 ft long.

-70-

medium, and explosive type (for single- charge detonations). Close and intermediate range peak overpressures for most cratering experiments attenuate

-1.2 with distance approximately as Rs The largest transmission factor observed for a given experiment will thus provide an indication of the maximum expected damage-producing airblast from any experiment at the s a m e scaled burial depth with the s a m e explosive in the same medium.

.

Calculated transmission factors for all buried Trinidad experiments are listed in the last column of Tables D1 through D4. compare the various experiments.

These values wil l be used to

SINGLE-CHARGE BURIED EVENTS

The most consistent airblast resul ts are generally obtained from single-charge events. Therefore, it i s of interest to examine Detonations BJ through B8. three ammonium nitrate f u e l oil (ANFO) events, B1, B2, and B3, show considerable scatter. Va lues o f f are comparable t o the other single-charge events, although B2 and B3 appear ra ther low. Values of f for B1 and B3 are higher than for any of the other (aluminized s lu r ry ) experiments, but those for B2 are lower. B2 w a s intermediate between B1 and B3 in scaled depth. The e r r a t i c behavior of the gas-vent airblast from ANFO detonations i s believed t o be a result of e r r a t i c vent t imes that are not closely correlated with scaled depth of burial.

The

g s

gv

16

The aluminized ammonium-nitrate s l u r r y events show more consistent behavior. Va lues of f for ground-shock

(f ) and gas-vent (f ) are plotted as a function of scaled depth of burial in Fig. Dl . In this case, f decreases slowly with increasing scaled depth of burial, as expected. A straight line i s fitted through the maximum values of f observed for TNT experiments at com- parabble scaled depths. show more deviation, indicating that some scat ter of the vent t imes occurs for these experiments as well. However, f does

gv decrease sharply with increasing depth, as it should. The plotted values of f are greater than those observed for TNT events at comparable scaled depths by a factor of two to ten. drawn through the maximum values of f

the lower curve is considered the best estimate of the maximum gas-vent t ransmission factors for typical events.

gs gv

gs

which a r e approximately twice those gs

Values of f gv

gv

Two curves are

gv'

ROW-CHARGE EVENTS

Airblast from a row of equal-size charges a t a given scaled depth is g rea t e r than the airblast that would be produced by only one of the charges detonated at the same scaled depth. ment of airblast for row-charge events is usually measured by the ra t io of the peak overpressure (or value of f), a t a given distance from the row, t o the peak overpressure (o r value of f ) a t the same distance from a single charge of the same weight as the average weight of the charges in the row and at the s a m e average scaled depth of burial. This ratio is known as the "difference factor" between row and single charge airblast.

The reinforce-

The difference factors for past experiments under partially controlled

-71-

C 0 .- ul ul .- 5 c e

I-

o. o

0. oc

A Ground shock, f

o Gas vent, f

9s

9V

\ \

0

Fig. D1. Observed single-charge transmission factors as a function of scaled ' depth of burst for aluminized ammonium nitrate s lu r ry detonations, Project Trinidad.

-72-

conditions have been found to fit a law m The scaled depth of burial. of the form: QD The scaled spacing between charges.

B Difference factor = n

where n = number of charges in the row and B = a n exponent whose value depends; upon the following:

0 The azimuth, relative to the align- ment of the row, at which the a i r - blast is observed. "B" will be a maximum fo r observations perpendicular t o the row, and wil l decrease at azimuths closer t o the row axis.

m The rock type I. The type of explosive .I. The average charge weight e The absolute length of the row I. The scaled range at which the air-

blast i s observed. Difference factors and values of B

have been calculated for the Trinidad row experiments. F i r s t , the average charge weight and the average scaled depth of burial for each row w e r e determined (Table D1). The observed overpressures

Table D5a. Ground-shockinduced overpressure reinforcement correction factors for Trinidad row-charge detonations. AP(row charge) = n B AP(sing1e charge at same scaled range)

Detonation Direction Difference

B B n factor, n ~

C1 Perpendicular to row Parallel t o row

c 2 Perpendicular to row

c 3 Perpendicular t o row Parallel t o row

Parallel t o row

5 2.44 0.554 1.60 0.292

5 3.31 0.744 1.23 0.128

7 3.08 0.578 2.30,l .51a 0.428, 0.212a

c 4 Perpendicular to row 5 (0.622 Ib <O (delay = Parallel t o starting end (0.727) < O

c5 Perpendicular to row 5 (0 .850)b <O 0.05 sec) Parallel to final end (0.781) <O

(delay = Parallel t o starting end 1.13 0.07 6 0.025 sec ) Parallel t o final end 2.29 0.51 5

C6 Perpendicular to row loc 4.90 0.690 Parallel t o row 3.21 0.506

D1 Perpendicular to row, uphill 9 8.42 0.97 Perpendicular to row, downhill 6.83 0.874 Parallel t o row 2.46 0.41

D2 Perpendicular t o row Parallel t o row

5 4.55 0.940 3.56 0.789

D3 Perpendicular to 1-ton row 6 4.07 0.784 Parallel to 1-ton row of 1 ton 1.13 0.068 Perpendicular t o 2-ton row 6 Parallel to 2-ton row of 2 tons 2.42 0.4 93

- -

a

bValues in parentheses indicate airblast overpressures less than comparable fitted

T w o parallel 5-charge rows; data reduced as airblast from single 10-charge row.

-73-

Two values given because signal showed double peak; larger value listed first.

single-charge values; considered somewhat questionable.

' a C

and distances w e r e then scaled according to the average charge weight, and values o f f were calculated, The largest observed value of f in each direction for each experiment w a s compared t o the value o f f for a single-charge experiment at the same scaled depth of burial (see Fig. Dl), and the difference factor was calculated: difference factor = f row- charge/f single charge f o r the same scaled depth. The ground-shock line in

Fig. D1 was used to obtain the value of f for a single charge, and the lower of the .two curves through the gas-vent values was used to obtain f for a Single charge. The calculated difference factor are listed in Table D5a (ground-shock observations) and Table D5b (gas vent observations ).

gs

gv

Because the number of charges for each experiment i s known, the value of B can be calculated. The B-values are

Table D5b. Gas-vent-induced overpressure reinforcement correction factors for Trinidad row-charge detonations. AP(row charge) = n AP(sing1e charge at same scaled range) B

Difference B factor, n B Detonation Direction n

c1

c2

c 3

c4 (delay = 0.05 sec )

c 5 (delay = 0.025 sec )

C6

D1

D2

D3

Perpendicular to row Parallel to row Perpendicular to row Parallel to row Perpendicular to row Parallel to row Perpendicular to row Parallel to starting end Parallel t o final end Perpendicular to row Parallel to starting end Parallel to final end Perpendicular to row Parallel t o row

Perpendicular t o ro*, downhill Parallel to row

Parallel to row Perpendicular to 1 -ton row 6 Parallel t o 1-ton row Perpendicular to 2-ton row 6

Perpendicular to row, uphill 9

Perpendicular to row 5

of 1 to

Parallel to 2-ton row

5 1.63 1.19

5 1.80

7 3.50 2.16, 2.44b

5 2.03 2.37 2.33

1.50, 1.21 1.95

5.66,4.42

(1 .o)a

5 1.36 d

1 oe 9.26, 5.42d

(1 . O ) (0.505) 1.26 3.67

(0.88) 3.05 1.73 2.92

of 2 tons 1.62

0.304 0.108 0.365

( 0 ) 0.644 0.396, 0.459 0.44' 0.536 0.526 0.191 0.252, 0.117d 0.415 0.966,0.734 d 0.753,0.645

b

(0 ) <O

0.105 0.808

< O 0.622 0.306 0.598 0.269

~ a Values in parentheses indicate airblast overpressures less than comparable Eitted single-charge values; considered somewhat questionable.

bLarger of two listed values derives from questionable airblast measurement. Questionable because of the very rapid attenuation of gas-vent overpressures with C

distance perpendicular to the C4 row. dTwo values given because signal showed double peak; larger value listed first. e Two parallel 5-charge rows; data reduced as airblast from single 10-charge row.

-74-

a listed in the last column of Tables D5a and D5b.

Experiment D3 consisted of two six- charge rows, but the separation and t ime delay between the rows were sufficiently great that almost no airblast interaction o r reinforcement occurred; therefore, the pulses from each row w e r e treated as if they originated from two separate six- charge rows and were analyzed separately. The C6 double row, on the other hand, had no interrow delay. the two rows could not be identified, and the event was treated as a single ten- charge row (rather than two five-charge rows 1.

Separate signals from

It should be noted that, except for D1,

with scaled depth of burial, number of charges in the row, o r scaled spacing between charges.22 The reasons for this e r r a t i c behavior a r e not fully understood, but are believed t o be related to the in- homogeneous nature of the medium, relatively small charge weights, and i r regular venting behavior, experiments showed highly complex waveforms in which some peaks could not be positively identified o r interpreted. Irregular and unexplained variations in vent t imes between the individual charges in a row may have contributed to the scat ter in the data. The ground-shock- induced pulses showed complex multiple peaks for some experiments.

Many of the

It i s im- all rows consisted of aluminized ammonium- possible to establish completely consistent nitrate s l u r r y charges in rock very s imi l a r to that of the B-series tests. Therefore, the comparison of single- charge values of f from Fig. D1 to f values for the row-charge events should be valid. Experiment D1 used ANFO and may show the e r r a t i c gas venting behavior noted for the single charge ANFO experiments. The value of f f o r D-1 did indeed turn out to be very low (Table D5b), being comparable t o that expected fo r a single-charge (B - 0).

The B-values in Tables D5a and D5b show an enormous amount of scatter, varying all the way from B = 0 (single- charge airblast) t o B =: 1.0 (perfect acoustic reinforcement). The average values tend t o be somewhat g rea t e r (more reinforcement) than those previously determined for relatively large- yield

gv

r o w s (charge weights -10 tons), but less than the observed reinforcement for a

22 small-yield rows (charge weights -64 lb). No definite correlation could be established

relationships bet ween single- and row- cha.rge airblast s imilar to those found for experiments in more uniform media, However, best estimates of the row- charge difference factors are given in Table D6. The conclusions discussed below must be considered tentative at best:. A more extensive discussion of the observed overpressures and attenuation r a t e s for individual row-charge events i s given in Ref. 16.

Waveforms observed off-the-end-of and perpendicular to the D4 (RR1) double row w e r e of extraordinary complexity. The length of the rows and the interrow delay, a s well as the inconsistent venting behavior from charge to charge within a row, caused various pulses to overlap and reinforce in a complex manner' dependent on azimuth and range. rendered the source of some peaks unidentifiable, particularly off the end of the rows. F o r these reasons, scaling of the overpressures and determination of

Overlap

-7 5-

Table D6. Airblast amplitudes for row-charges expressed in t e r m s of single-charge airblast amplitudes.

Ground-shock-induced Gas-vent-induced Conditions overpressures overpressures

I Delayed (intercharge) row-charges Perpendicular: delay A T = 0.25 sec/ton ' p A P r gaps

Simultaneous row- charge Perpendicular Off-the-end

Off-the-starting end AP; = AP,

Off-the-finish end ' p A P ~ = n 0 . 5 npS I r n

A T = 0.025 sec/ton

A P r = n 0.75 A P s

A P = n 0.5 A P s r

AT = 0.050 secfton'/J A P r A P s

aEstimate based on very limited data.

the reinforcement factors cannot be accurately accomplished. It is hoped that t h i s situation wil l improve when more data from long rows become available. Meanwhile, the D4 data cannot be included in the "reinforcement factor" analysis, and we can only predict approximate "maxim um" expected reinforcement factors for very long o r complex rows based on the particular case in question.

Other problems with the D4 measurements include inconsistent attenuation rates in a given direction (related to the problems mentioned above), and some questionable data points as noted in'the

16 I table.

A P r = n 0.6 A P s A p = n 0.45 A P s

r

a 0.45t00.55 A pS

A P r - n

A p g n 0.45 A P s r

The principal characterist ic of the airblast data for row-charges i s the large amount of sca t te r . observed difference factors (i.e., airblast reinforcement) for all experiments in this s e r i e s have a fairly well-defined upper bound for each component of the airblast pulse (gas vent and ground shock). estimated upper limits, as listed in Table D6, may be used to predict reliably the airblast amplitudes for s imilar experi-

However, the

These

-7 6-

ments. presented in Table D6 should apply most accurately for detonations s imilar to those at Trinidad; i.e., five to ten charge rows, charge weights from 0.5 to 2 tons, near- optimum intercharge spacing (1 6 to '

3 5 f t / t ~ n ' / ~ ) , and aluminized ammonium- nitrate s l u r r y explosive in weak rock. These difference factors apply either to the peak single-charge overpressures A F s at intermediate ranges, o r t o the maximum single-charge values of f .

F o r single row-charges, Table D6 relates overpressures generated by the row-charge ( A P r ) to those generated by a single charge ( A P s ) weighing the same as the average charge in the row and at the s a m e scaled depth of burial. number of charges in the row i s n.

Estimates of the difference factors

The

F o r simultaneous double row-charges near optimum interrow spacing, the overpressures and difference factors w e r e approximately the same as for a single row containing the same number of charges as both double rows; i.e., n i s the total number of charges in both rows.

The single -charge t ransmiss ion factors (Fig. D1) and row-charge

difference factors discussed in this chapter may be used as an approximate

means of predicting airblast from future events of a similar nature. 22

-77-

Appendix E Laboratory Testing of Fallback Material

t 4,

J. M. Duncan"' and C. K. Chan

testing a t the Rockfill Test Facility were found to have an average water content of 4.870, which is about the same value as determined from core samples of the 1

3 A program of laboratory tests w a s con- was determined by excavating 107.2 yd from a trench and weighing the material. The grain-size was measured using the

ducted at the Rockfill Test Facility at the University of California".". to measure the

.I, .I,

i o physical properties of the fallback in the D4 c ra t e r .

The t e s t s described w e r e performed fo r two purposes. w a s to obtain information that could be used t o estimate the amount of t ime- dependent settlement of the fallback, and the amount of settlement that would result f rom saturation of the fallback by surface water or groundwater. of the test program w a s to provide information concerning other physical properties of the fallback, such as grain-size distribution, relative density, and shea r strength characteristics, that would add to the available information concerning the engineering characterist ics of fallback mater ia ls in general.

The pr imary objective

A second objective

The rocks, which are composed of quartz, plagioclase and orthoclase feld- spars , clay, and minor amounts of ferromagnesian minerals, a r e soft and poorly cemented. Although they do not slake when placed in wa te r , they are softened by water and many sandstone fragments could be broken easily by hand after soaking in water. in s i t u dry density of the rock before the

3 blast was 150.8 lb/ft . A s described in Chapter 6, the m a s s density of 128.8 lb/ft

The average

3

4, -8-

Associate Professor of Civil Engi- neering, University of California, Berkeley.

California, Berkeley.

the Richmond Field Station. i s operated

?Research Engineer, University of

J, 4, ,I. 1-

The Rockfill Test Facility, located at

11 point-count technique. The fallback contained a few rocks a s large a s 4 o r 5 ft , but about 99% of the particles w e r e sma l l e r than 15 in. f iner than the No. 200 sieve.

The smallest particles w e r e

Thirty-four tons of the excavated fallback material w e r e trucked to the Rockfill Test Facility for testing. Samples w e r e taken f r o m the material to determine its water content. The entire 34 tons w e r e sieved to determine the grain- size distri-

bution and to separate the material into a number of size fractions, the smallest consisting of material passing the No. 200 sieve. The size fractions w e r e subse- quently recombined to form "model" materials with grain-size distribution curves parallel to the lield curve, but with smaller maximum particle sizes. Tests were conducted on these model mater ia ls to determine maximum and minimum densities for relative density determinations, and triaxial and one - dimensional compression tests w e r e performed to determine the stress- s t ra in and strength characterist ics. Tests w e r e conducted on specimens compacted to the in s i t u relative density and to looser densities . WATER CONTENT AND IN SITU DRY DENSITY

Samples from the material received for

by the University of California for the California Department of Water Resources. ! rocks before the blast. Using a water

-78-

content of 4.8% and the moist unit weight determined by trenching in the fallback

= 128.8 lb/ft ) the in situ dry unit ('In weight (yd) was calculated to he 123.0 lb / ft3.

3

GRAIN SIZE DISTRIBUTION, PARTICLE COMPOSITION, AND SPECIFIC GRAVITY

The grain-size distribution curve determined by sieving the fallback mate- r i a l received at the Rockfill Test Facility is shown in Fig. E l , together with curves determined by the point-count technique at the east and the west ends of the crater . The curve determined by sieving l ies between the other two curves for the range of s izes l a rge r than about 0.2 in., but shows l a r g e r percentages of the finer sizes. It is seen that 23% of the fallback is finer than the No. 4 sieve, and about 270 is finer than the No. 200 sieve.

The grain-size distribution curves for the "model" materials are shown in Fig. E2. the grain-size curve of the material received for testing, and were selected s o that the largest s i ze particles u s e d in each type of test were about one-sixth zs large as %he minimum dimension of the tes t specimen.

These curves a r e parallel to

The material w a s examined after sieving to determine the cornpositions and specific gravities of the various s i ze fractions, as shown in Table E l . The shale and siltstone w e r e softer than the sandstone and were ::herefore broken into smaller particles by the blast. resjtllt, the sma l l e r particles tend to be somewhat softer than the l a r g e r ones. The same would probably be true of any fallback containing rocks with varying hardness, The specific gravities determined for the various s ize fractions

A s a

U.S. sieve size - in.

#200 #lo0 150 I 3 0 #16 #8 #4 3/8 3/4 1-1/2 3 6 12

Determined by point count technique

- - I c I:

L al C u-

C al

.- t 40

E II-

* O L 0

East end of crater

West end of crater,,y

Trinidad fa1 I back

0.01 0.1 Opening -- in.

d l I '34-ton sample-

/'

24

deterrnined.by sieving

1 10

Fig. E l . Comparison of grain-size distribution curves determined by point count technique arid by sieving.

- 7 9 -

U.S. s ieve s ize - in.

1

+ L rn al

x

.- 3

11

S t .- cc c C al

al a 2

Opening - in.

Fig. E2. Grain-size distribution curves for material as received and for t e s t specimens.

Table E l . Composition and specific gravities of various sized fractions of Trinidac fallback .

Percent P e r cent shale Specific gravity

Size fraction (in.)

6 t o 3 91

sandstone and siltstone

9 2.60

- 98 2

67 3 3

3 t o 1-1/2 16 2.64 1-1/2 to 314 a4

- 314 t o 318 2.66 - - 318 t o No. 4

No.4 t o No. 8

finer than No. 4

- 50 50

- 2.60 All material -

varied from 2-60 to 2.66, with an average value of 2.63.

four "model" materials having grain-SiZe distribution curves parallel to that .for the field material, but sma l l e r maximum particle sizes. Tes t s w e r e performed on materials with maximum particles sizes equal to 2 in., 1 in., 1/2 in., and the No. 4 sieve s ize .

RELATIVE DENSITY

Tests w e r e performed to determine the maximum and minimum densities f o r The results of these tests

-80-

are shown in Fig. E3. The maximum a

90

80

and minimum densities increase with increasing maximum particle size. Extrapolating the experimental curves to a maximum particle s i ze of 15 in., it was estimated that the maximum density of the material with the field gradation would

3 be about 130.0 lb/ft , and the minimum 3 about 109.5 lb/ft . Using these values of

maximum and minimum density, it was determined that the relative density of the fallback in the field was about 7070,

This relative density of the fallback in the field i s somewhat higher than was anticipated. However, studies by Walker

23 and Whitaker21 and Silver and Seed have shown that uniform sands can be compacted efficiently by "pluvial compaction," o r dropping into place. and Seed found that a uniform, angular si l ica sand that they tested could be

Silver

Minimum density -

I I 1 I - specified by ASTM D 2049-69 -

compacted t o as high as 95% relative density by pluvial compaction. writers ' knowledge, no studies have been performed to determine the effectiveness of pluvial compaction for well-graded materials like the Trinidad fallback.

To the

TRIAXIAL TESTING

Most of the triaxial and one-dimensional compression test specimens were formed a t relative densities close to those determined for the fallback in the field, in order. that the results of the tes t s could be used to evaluate the properties of the material at its in situ density. A few tes t s on smaller size specimens were performed at looser densities to investigate the effects of changes in density on the strength, compressibility, and compression due to wetting,

U.S. seive size - in.

#200 #lo0 #50 #30 #16 #8 #4 3/8 3/4 1-1/2 3 6 12 1301 I I I I I I I I I I I / c ' O " n

Fig. E3. Variations of maximum and minimum density with maximum particle size.

-81 -

Four drained triaxial t es t s w e r e performed on 36-in. diameter specimens containing particles as large as 6 in. The grain-size distribution curves for the material tested are shown in Fig. E2. The specimens were compacted to dry

3 densities ranging from 119.6 lb/ft to 120.6 lb/ft , which corresponds to relative densities of 71 f 20J0, very close to the field value.

3

Two tes t s were conducted on material that was compacted and tested at water contents of 570, essentially the same as the field value. w e r e saturated after compaction by circulating wa te r through them and by applying back pressure. The permeability of the material w a s quite low, and considerable t ime w a s required to saturate the specimens. After the tests the wet specimens did not drain; they had considerable cohesion and were able to stand unsupported, as shown in Fig. E4.

The s t ress-s t ra in and volume change

The second two specimens

curves for the two tes t s performed using u3 = 15 psi a r e shown in Fig. E5, and those for tests conducted with u3 = 30 psi are shown in Fig. E6. The s t ress-s t ra in curves shown in Figs. E5 and E6 and in other figures in this report have not been corrected for the loads carr ied by the rubber membranes used to confine the specimens. The loads are not very large, however, and applying the appropriate correction t o the axial stress results in a reduct ion in the maximum principal stress ratio of the order of 0.1, o r about 2%. Although the values of principal stress ratio shown on the s t ress-s t ra in curves have not been corrected, the stresses at failure have been corrected for the purpose of calculating the angles

Fig. E4. Wet specimen (36-in. diameter) after testing.

of internal friction, which a r e discussed in a subsequent section.

It may be noted that the wet specimens were considerably weaker than the dry ones. wet specimens a r e flatter than for the dry ones tested at the same pressure, and the peak values of principal s t r e s s ratio a r e smaller.

The s t ress-s t ra in curves for the

It may also be seen

-82-

V .-

I I I I

Wet

- Trinidad fal lbock 36 in . dia . specimens maximum w r t i c l e size = 6 in. [ Dr = 71 %’

0 = I5 psi 3

Dry

L

-15 0 5 10 15 20 25 5

9 - A x i a l s t ra in - %

Fig. E5. Stress-s t ra in and volume change curves for specimens compacted t o 71% relative density (confining pressure, 15 psi).

b

1 5

: 4

0 .- +

Y) Y)

? z 3

u 2

1

r inidad fallback 6 i n . dia . specimens

maximum ar t ic le size

- x .- S

a .- I

--t

0 5 10 15 20 25 5 9 A x i a l s t ra in - 91 -

Fig. E6. Stress-s t ra in and volume change curves for specimens compacted t o 717’0 relative density (confining pressure, 30 psi).

that the wet specimens compressed more during shea r than the dry ones. material is quite compressible; even a t the low confining pressures employed in the tests, the volumes of all the specimens decreased during shear .

The

Four drained triaxial tests were conducted on 6-in. diameter specimens. A s was the case in the tes t s on 36-in. diam- e t e r specimens, two specimens were tested wet and two were tested dry, using confining pressure of 15 and 30 psi. The maximum particle s ize in the 6-in diam- e t e r specimens was 1-in. were prepared at densities of 114.1 to

3 114.8 lb/ft , correspond to relative densities of 7 7 * 1%.

The specimens

The s t ress-s t ra in curves for the tes t s A s in the a r e shown in Figs. E7 and E8.

case of the 36-in. diameter specimens,

‘ m

Trinidad fal lbock 6 in . d ia . specimens muximum part icle size =

0 5 10 15 20 . 2 5 5 3 - A x i a l s t ra in - %

Fig. E7. Stress-s t ra in and volume change curves for specimens compacted to 77% relative density (confining pressure, 1 5 psi).

-83-

b

1 5

2 4

2

0 .- +

VI VI

- 2 3 Trinichd fal lback

.- K maximum part icle size v 2

& 1

I -5

6 i n . d ia . specimens

8 .- L-

2.8 i n . dia . specimens

* P I 1 I 1 1 1 G -15 0 5 10 15 20 25 E,

2 Axial strain - -

Fig. E9. Stress-strain and volume Fig. E8. Stress-s t ra in and volume change curves for specimens

change curves fo r specimens compacted t o 77% relative density (confining pressure, 15 psi). 30 psi).

compacted to 73% relative density (confining pressure,

the specimens tested wet w e r e considerably weaker than the dry ones, and compressed more during shear .

Eight drained triaxial t e s t s w e r e con- ductkd on 2.8-in. diameter specimens, with materials having a maximum particle s i ze of 0.47 in. tests were conducted on wet specimens that w e r e compacted t o dry densities of 108.8 lb/ft ing to relative densities of 7170 and 73%. The s t ress-s t ra in curves for these tests are shown in Figs. E9 and E10, together with s t ress-s t ra in curves for dry material at the same relative density estimated from the resul ts of tests on d ry specimens

Two of these

3 3 and 109.3 lb/ft , correspond-

* m

rinidod fal lbock

0 5 10 15 2 0 . 25 Axial strain - ?h 5

9 -

at higher and lower densities. The remaining s ix tests on 2.8-in.

diameter specimens were conducted on dry specimens with relative densities

Fig. E10. Stress-strain and volume change curves for specimens compacted t o 7370 relative density (confining pres'sure, 30 psi).

-84-

ranging from 54.570 to 80.570. The stress- e st rain and volume change curves for these tes t s are shown in Figs. E l l and E12.

ONE-DIMENSIONAL COMPRESSION TESTS

Eight one-dimensional compression tes t s were conducted on material having a gradation curve parallel to the field gradation curve and a maximum particle s ize equal to the No. 4 sieve. The tes t s w e r e conducted on specimens confined in 4-in. diameter, 1-in. high Teflon-lined consolidation rings. Two series of tes t s were performed, one on specimens compacted to 8070 relative density, and the . other on specimens compacted to 5070

relative density. The compression-time curves for one

of these tes t s is shown in Fig. E13. The s p e c i m en w a s c om pact e d dry - t o - 8 0% relative density and was then subjected t o a p re s su re of 10 psi. Application of this pressure resulted in an immediate axial compression of about 0.870, followed by a small amount of time-delayed compression. Similarly, increasing the p re s su re to 20 psi and then to 30 psi resul ted in f u r t h e r immediate compression followed by creep at a slow rate.

A s shown in Fig. E13, adding water t o the specimen while the p re s su re was maintained at 30 psi caused a large in- c r e a s e in the settlement rate. Over a period of 100 min. after the water was added, the settlement increased from about 2.8 t o about 9.4%.

The results for all four one- dimensional compression t e s t s performed on specimens compacted to 80% relative density a r e shown in Fig. E14. These four specimens were wetted while

e1 I 5

:? 4

:!

0 . -- +-

"1 "7

t; 3 T r i n i d a d f a l l b a c k

!L 2.8 in. dia. spec imens rnax.

-- p a r t i c l e s i z e = 0.47 ii . --

u 2

a- 1 0

I -5

CI . --

CJ

u I

. -- t- -15 UJ E 5 10 15 20 25

__ Ax ia l strain - % =. a

Fig. E l 1. Stress-s t ra in and volume change curves for specimens compacted to three relative dens it ies (confining pres sure, 15 psi).

b

1 5

p 4 F z 3 x *z 2

1 0

0 .- c

VI m

-

.- L a

c .-

$ -15

- Axial s t r a i n - % 0 5 10 15 20 25 5

3 Fig. El:?. Stress-s t ra in and volume

change curves for specimens compacted to three relative densities (confining pressure, 30 psi).

-85-

5 .- e .E 6 Q

c wl

- X

10 psi t

20 psi - 30 psi c

Water added

Trinidad fallback Maximum particle size = No. 4 Dr = 80%

I I I I I I I I I I I 1 0.1 1 10 1 00 400

Time after loading - rnin.

Fig. E13. Compression t ime curves for specimens compacted to 80% relative density.

Swelling due to wetting a t 0.1 psi lid 0

8 I -4 C .- e + v) - 0 -a - .- X

Q t Trinidad fallback r;Ei;g particle size = NO. 4

Fig. E14. One-dimensional compression curves for specimens compacted to 80% relative density.

-8 6-

subjected to pressures of 30, 20, 10, and 0.1 psi. The specimen which was

PARTICLE BREAKAGE

wetted at 0.1 psi swelled about 2.6% when the water w a s added, but all the others compressed upon wetting. Similar r e - sults for specimens compacted to 50% relative density are shown in Fig. E15. A s would be expected, the amount of swe l l induced by wetting at the lowest p re s su re was smaller, and the amounts of compression due t o wetting at higher pressures were l a r g e r for these looser specimens.

As for other soils tested previously, the amounts of compression induced by wetting the specimens after loading were approximately equal t o the difference in the amounts of compression for wet and dry specimens at the same pressure. Thus the amount of compression due to wetting at any pressure can be estimated with compression curves fo r wet and dry specimens.

Several specimens were sieved to determine the amount of particle breakage during testing. The results are shown in Table 2 in t e r m s of the particle breakage factor B, defined by M a r ~ a l . ' ~ ~ This factor is the sum of the differences (of the same sign) in the percentages retained on each sieve before and after a test . Larger values of B indicate more change in gradation and more particle breakage during the test. indicate that the particle breakage was

The data in Table E2

Table E2. Va lues of particle breakage factor B determined by resieving triaxial specimens after testing.

Specimen d i a m e t e r 36 in. 6 in. 2 .8 in. Confining

pressure Dry Wet Dry Wet D r y Wet ( p s i ) (%) ( 7 0 ) (%) (70) ( 7 0 ) (%)

I. 5 6 18 11 2 6 10 2 1

3 0 6 15 10 23 9 1 7

Swelling due to wetting a t 0.1 psi L

Maximum particle size = No. 4

1 Dr =50y0 '

compression

,Wet compression

. -

0 5 10 15 20 25 30 35 Axia l pressure - psi

Fig. E l 5. One-dimensional compressiori curves for specimens compacted to 50% relative density.

-87-

The relative density of the fallback in the field is perhaps the most important factor controlling its shear strength, compressibility, compress ion upon wetting, and susceptibility t o settlements o r liquefaction during earthquakes. Mate- rials with relative densities as high as that determined for the Trinidad fallback (70700) are nearly as dense a s well- engineered fills and should thus not be susceptible to severe problems of settlement and stability.

In o rde r to determine the relative density of the fallback in the field, it was necessary to extrapolate on the basis of minimum and maximum density values determined for model materials with sma l l e r maximurn particle sizes. Be- cause of the importance of knowing the relative densities accurately, it would be desirable to study the effectiveness of pluvial compaction for well-graded fallback materials. If enough data could be obtained for various types of materials, it might be feasible to predict the relative density based on small-scale laboratory and/or field tests conducted before the crater was made.

The results of all the triaxial tests

g rea t e r for the wet than for the d ry specimens. w a s more breakage for the smaller specimens that contained smaller, softer particles .

It may also be noted that there

SUMMARY OF LABORATORY TEST PROGRAM

-88-

performed are summarized in Table E3, and the measured values of $ are plotted against the relative densities of the test specimens in Fig. E16. All of the values shown in Fig. E16 are for tes t s conducted

with u3 = 15 psi; as shown in Table E3, the values of Q are about 1 to 2 deg lower for tests conducted with a3 = 30 psi.

It may be seen that the angles of internal friction a r e about 6 deg lower onathe average for wet specimens than for dry ones. for all three specimen s izes are in fairly good agreement, indicating that it would be possible to determine the angle of internal friction with reasonable accuracy by testing "model" materials, even though the particles in the various size ranges vary in hardness.

The values o f $ measured

F o r the in situ relative density of 700/0, the angle of internal friction for the material in a dry condition is about 43 deg, and for the material in a wet condition, about 3 6 . 5 deg. These values correspond to a3 = 1 5 psi as in Fig. E16; the values of 4 for both wet and dry conditions would be somewhat smaller for higher confining pressures .

The values of volumetric s t ra in due to wetting measured in the triaxial and one-dimens ional compress ion tests are shown in Fig. E17, plotted against the maximum particle sizes. that the specimens composed of smaller s izes underwent much more compression due to wetting than did those containing l a rge r particles. By extrapolating the curves to the maximum particle s i ze in the field (about 15 in.), it is possible to estimate the amount of settlement which would be induced by wetting. A s may be seen for the data obtained in one-. dimensional compression tes t s on specimens composed of material with No. 4 maximum particle size, the compression induced by wetting under at-rest pressure conditions is about 20% greater than

Tt may be seen

Table E:!. Summary of tr iaxial tes t results.

Principal Angle of internal friction,

s t r e s s Confining Density, Relative ratio, pressure, density, Maximum

particle 4

(deg) Dr

Test (in.) (psi) (1 b /ft ) ( 7 0 )

(5 'd s i ze 3

36-in. Dry 6 36-in. Dry 6 3 6-in. Wet 6 36-in. Wet 6

6-in. Dry 1 6-in. Dry 1 6-in. Wet 1 6- in. W e t 1

2.8-in. Dry 0.47 2.8-in. Dry 0.47 2.8-in. Dry 0.47 2.8-in. Dry 0.47 2.8-in. Dry 0.47 2.8-in. Dry 0.47 2.8-in. Wet 0.47 2.8-in. Wet 0.47

1 5 3 0 1 5

3 0

1 5 30 1 5

30

1 5 3 0

15 30 1 51 30 1 51 30

120.3 71.5 120.3 71.5 120.6 73 .o 11.9.6 69.0

11.4.1 76.0 11.4.3 76.0 11.4.8 78.0 11.4.5 77.0

11.1.3 80.5 11.1.0 79.5 106.8 63.5 106.1 61 .O

105.0 56.5 104.5 54.5 108.8 71.0 109.3 73 .O

5.32 4.95 3.82 3.58

5.92 5.44 4.08 3.98

5.23 4.93 4.76 4.81 4.87 4.65 4.21 3.65

43.1 41.5 3 5.8 34.3

45.3 43.6 37.3 36.7

42.8 41.5 40.8 40.0 41.2 40.2 38.0 34.7

the volumetric s t ra in induced by wetting in tr iaxial tests with the specimens confined under equal all-around pres - s tires.

Using the extrapolated curves shown in Fig. E17 and allowing for about 2070 higher volumetric s t ra ins under a t - rest p ressure conditions, it is estimated that the compress ion due to wetting would amount to about 0.9% with overburden pressure (a l ) equal t o 15 psi, and about 1.570 with overburden pressure equal to 30 psi. Fig. E18, which shows the relationship between the overburden pressure and the percent compression due to wetting under at- rest pressure conditions.

These values a r e plotted in

With this curve, calculations have been made to determine the settlements to be expected in fallback layers of

various thicknesses if the groundwater rose to within 5 f t of the ground surface. The results of these calculations a r e shown in Table E4. It may be seen that the expected settlements due to ground- wa te r r i s e exceed one-tenth of a foot for layers more than 20 f t thick, and that they a r e more than 0.2 f t for layers thicker than about 30 f t . The results would be somewhat different if the groundwater rose to some level other than 5 f t beneath the surface, but the settlements due to wetting could be estimated using the same procedures.

-89-

0 a,

-0

I -8

C 0

V

. .- c .- L rc - 0

aJ C

0 al 0 C

E c .- cc

- 4

50 I I I I I I I I

4 6 .

42

38

34

36-in.

6-in.

28-in.

Trinidad fa1 o3 = 15 psi

diam

diam

d iam

lback

o Dry o Wet

Dry Wet -

,ecimen

2ecimen / a Dry a Wet specimen

t 1 30 I 1

30 40 50 60 70 80 90 100 Relative density - YO

Fig. E16. Variations of angle of internal fri.ction with relative density.

U.S. sieve size - in.

#200 #lo0 #50 #30 116 #8 #4 3/8 3/4 1-1/2 3 6 12 24 10 I I I I I I I I I I I

o Triaxial tests (03 = al )

x 1-D compression tests -Maximum particle size (03 = KO01 ) X of fallback in-situ

1

Maximum particle size - in.

Fig. E17. Variation of volumetric s t ra in due t o wetting with maximum particle size.

-90-

I r r \

a 1.6-

0 4 8 12 16 20 24 28 32 Effective overburden pressure - psi

I 1 1 I I I I I - -

I 1 I I I I

-

Fig. E18. Variation of compression due to wetting with overburden pressure for a t - res t pressure conditions.

A small amount of creep settlement of the fallback would be expected even if the groundwater did not r i se . shown in Fig. E13 indicate that the compression of the dry fallback continues to increase approximately linearly with the logarithm of time. shown in Fig. E13 indicate that the settlement ra te i s independent of pressure, and amounts to about 0.1% per log cycle of time. Thus the creep settlement of a 10-ft thick layer would be expected to amount to about 0.01 f t in the period from 3 to 30 days, an additional 0.01 ft in the period from 30 days to about 1 yr, another 0.01 f t in the period from 1 to 10 yr, and so on. These creep settlement rates are quite small and are not considered t o be significant.

The curves

The t ime curves

Settlement of the fallback would also be caused by increased static pressures

Table E4. Surface settlement due to groundwater r i s e within 5 ft of ground surface for various fallback layer thicknesses.

I n i t i a l e f f e c t i v e

~ ~ ~ \ ~ d ~ f o v e r b u r d e n L a y e r t h i c k n e s s , w a t e r r i s e , pressure’ ti) S e t t l e m e n t ,

T Er Pb AI1

5 0 0 0.00 0 .00

1 0 5 6 . 2 5 0 .40 0.02

1 5 10 8.32 0.52 0 . 0 5 20 15 10.4 0.64 0.10

25 20 12.5 0.76 0 .15

30 25 14.6 0.87 0.22

NOTe: E f f e c t s of r e b o u n d d u e t o b u o y a n c y are n e g l e c t e d .

f rom fills placed on the fallback o r from slowly moving trains. The magnitudes of these settlements could be estimated using the compression curves shown in Fig. E14 for wet o r dry material, which- ever is appropriate.

-91-

References

1. D. Fitchett, Middle Course I Cratering Series, U . S. Army Engineer Waterways Experiment Station Explosive Excavation Research Laboratory, Livermore,

Calif., Rept. NCG TR-35, June 1971. 2. C. Gardner and T. Shackleford, Project MINIMOUND, U. S. Army Engineer

Waterways Experiment Station Explosive Excavation Research Laboratory, Livermore, Calif., Rept. EERO/TM 71-10, March 1972.

3. K. Sprague, Middle Course I1 Crater Series, U . S. Army Engineer Waterways Experiment Station Explosive Excavation Research Laboratory, Livermore, Calif., Rept. TR E-73- (in preparation).

4 . J. Lattery, Project TRINIDAD: Railroad Relocation, Cuts RR2 and RR3, U . S. Army Engineer Waterways Experiment Station Explosive Excavation Research Laboratory, Livermore, Calif., Rept. TR E-73- (in preparation).

5. R . Gillespie, Hole Springing, U . S. Army Engineer Waterways Experiment Station Explosive Excavation Research Laboratory, Livermore, Calif. , Rept. TR E-72-24, June 1972.

6 . D. U . Deere, in Rock Mechanics in Engineering Practice (John Wiley & Sons, New Y o r k , 1968) , pp. 15-17.

7 . 13. Deere and R. Miller, Engineering Classification and Index Properties for Intact Rock, University of Illinois, Urbana, Ill. , Rept. AFWL-TR-65-16, December 1966.

8. R . Bourque, Crater Data: A Computer Code for Analyzing Experimental Cratering Tests, U. S. Army Engineer Waterways Experiment Station Explosive Excavation Research LFhoratory, Livermore, Calif., Rept. NCG/TM 70-15, October 1970.

9. B. Redpath "A Concept of Row Cra te r Enhancement, in Engineering with Nuclear Explosives (Proceedings, American Nuclear Society Symposium, Las Vegas, Nev., January 1970, vol. 1, CONF - 700101, 1970). S. Johnson, Explosive Excavation Technologx, U . S. Army Engineer Waterways Experiment Station Explosive Excavation Research Laboratory, Livermore, Calif., Rept. NCG-TR-21, June 1971, pp. 16-18.

10.

11. S. Johnson, - ibid, Chapter 5. 12. K. King, Project TRINIDAD, Delta Series Number 1, 2 , and 3, Sopris, Colorado,

U. S. Dept of Com., NOAA, National Ocean Survey, Special Projects Party, Las Vegas, Nev., Rept. CGS-746-9, December 1970.

13. T. ?'ami, Analysis of Ground Motion Peak Particle Velocities from Cratering Experiments a t Trinidad, Colorado, U. S. Army Engineer Waterways Experiment Station Explosive Excavation Research Laboratory, Livermore, Calif. , Rept. MP-E-73- (in preparation).

14. M. Kurtz and B. Redpath, Project Pre-GONDOLA, Seismic Site Calibration, U .S . Army Engineer Waterways Experiment Station Explosives Excavation Research Laboratory, Livermore, Calif., Rept. PNE 1100, Majr 1968.

-92-

15. J. A. Blume and Assoc., San Francisco, personal communication ( 1 H 7 1 ) .

16. L. Vortman, Airblast from Project TRINIDAD Detonations, Sandia Cor.:,oration, Albuquerque, N . Mex., Rept. SC-RR-71 0056, June 197 1.

17. B. D. Anderson, A Simple Technique to Determine the Size Distribution of Crater Fallback and Ejecta, U . S. Army Engineer Waterways Experiment Station Explosive Excavation Research Laboratory, Livermore, Calif. , Rept. NCG-TR-18, March 1970.

18. A. D. Frandsen, Analysis and Reevaluation of Bulking Factors, U . S . Army Engineer Waterways Experiment Station Explosive Excavation Research L*abora- .

tory, Livermore, Calif., NCG/TM 70-1, March 1970. M. G. Wolman, "A Method of Sampling Coarse River-Bed Materials," Transactions, American Geophysical Union, 35, 951-956 (1954).

19.

- 20. N. D. Marachi, C. K . Chan, H. B. Seed, and J. M. Duncan, Strength and De-

formation Characterist ics of Rockfill Materials, University of California, Berkeley, Rept. TE-69-5, September 1963. B. P. Walker and T. Whitaker, "An Apparatus for Forming Uniform Beds of Sand for Model Foundation Tests," Geotechnique 17, 161-167 (1967).

21.

- 22. C. Snell and D. Oltmans, A Revised Empirical Approach to Airblast Prediction,

U . S. Army Engineer Waterways Experiment Station Explosive Excavation Research Laboratory, Livermore, Calif., Rept. EERO TR-39, November 197 1.

23. M. L. Silver and H. I3. Seed, The Behavior of Sand Under Seismic Loading Con- ditions, Earthquake Engineering Research Center, University of California, Berkeley, Rept. EERC 69-16, December 1969 .

24. R. J. Marsal, Discussion, Proceedings, 6th International Conference on Soil Mechanics and Foundation Engineering,

P res s , Toronto, 1965) Vol. 3, pp. 310-316.

Montreal 1965 (University of Toronto

-93-

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(Security cla8ailicetion 01 title. hody 01 ebstrect and indexin& annolation musl he antered when the overa l l report is classifred) I. O R I G I N A T I N G A C T I V I T Y (Corporateruthor) I Z e . R E P O R T S E C L I R I T Y C L A b S l F l C A T l O h +- 2b. G R O U P

Unclas s i f i ed IJSAE Waterways Experiment S t a t i o n Explosive Excavat ion Research Laboratory

I ¶. R E P O R T T I T L E

P r o j e c t TRINIDAD - Explosive Excavati.on Tes t s i n Sandstone and Shale

4. D E S C R I P T I V E N O T E S <*ne Of ..part m d inclusiro date.)

F i n a l Technica l Report

Bruce B. Redpath

5 . A U T H O R I S I (Fir8t MW. middle initial, ia8t name)

I . R E P O R T D A T E ?a. T O T A L N O . OF P A G E S 76. NO. O F R E F S

J u l y 1972 100 24 Y. C O N T R A C T O R G R A N T N O . Sa. O R I G l N A T O R * S R E P O R T N U M B E R I S )

b. P R O J E C T N O . TR-E-73-1

c. Ob. O T H E R R E P O R T N O ( S ) (Any other numbers thst may be asslmed thie report)

I d.

10. O l S T R l B U T l O N S T A T E M E N T

Approved f o r p u b l i c r e l e a s e ; d i s t r i b u t i o n unl imi ted .

11. 5 U P P L E M E N T A R Y N O T E S 12. S P O N S O R I N G M I L I T A R Y A C T I V I T Y

3. A B S T R A C T

A s e r i e s of s i n g l e - , row-, and mul t ip le -charge c r a t e r i n g de tona t ions , w i th i n d i v i d u a l charge weights of one t o two t o n s , were c a r r i e d ou t i n weak, interbedded sands tones and s h a l e s near T r in idad , Colorado, i n 1970 and 1971. The p r i n c i p a l o b j e c t i v e s of t h e s e excavat ion experiments were: t o o b t a i n s ing le -cha rge c r a t e r i n g curves ; t o v e r i f y row-charge des igns f o r achiev ing a s p e c i f i e d excavat ion; t o determine t h e e f f e c t s of mi l l i s econd de lays i n row-charge c r a t e r i n g ; t o experiment w i th c r a t e r i n g i n vary ing t e r r a i -n ; . and t o compare t h e c r a t e r i n g e f f e c t i v e n e s s of s e v e r a l exp los ives . Three v a r i e t i e s of a luminized ammonium-nitrate b l a s t i n g agents and ANFO were used. A i r b l a s t arid se i smic e f f e c t s of each de tona t ion were monitored The s e r i e s culminated wi th t h e excavat ion of a 400-foot long ra i lway cu t w i th 44 t ons of exp los ives d i s t r i b u t e d among 32 charges .

UNCLASSIF'IED Security Classification

~

Security Classification

4 . K E Y W O R D S

Cratering Explosive Excavation Explosives Sandstone

L I N K A - R O L E -

L I N K 8 - R O L E -

L I N K C

R O L E - W T -

UNCLASSIFIED Security Classification

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Project Trinidad, Explosive Excavation Tests