In Situ Geophysical Investigation of the Pile Test Section ...crosshole method is that boreholes are required for testing. Thus, crosshole tests seismic tests are more costly than

Technical Report GL-94-1

0 ~ ~~Januar =

US Army Corpsof Engineers AD-A277 699Waterways ExperimentStation

In Situ Geophysical Investigationof the Pile Test Section,Sardis Dam, Mississippi

by Jos6 L. LiopisGeotechnical Laboratory

DTICELECTEAPRO 51994 D

Approved For Public Release; Distribution Is Unlimited

Pa r 10257 AmEnieDitc, b

Prepared for U.S. Army Engineer District, Vicksburg

The contents of this report are not to be used for adverticing,publication, or promotional purposes. Citation of trade tainesdoes not constitute an official endorsement or approval of the useof such commercial products.

PWMW1 CM4 RECYCED PAPt

Technical Report GL-94-1January 1994

In Situ Geophysical Investigationof the Pile Test Section,Sardis Dam, Mississippiby Jos6 L. Llopis

Geotechnical Laboratory

U.S. Army Corps of EngineersWaterways Experiment Station3909 Halls Ferry RoadVicksburg, MS 39180-6199

Accesion For

NTIS CRA&IDTIC TABUnannounced El

Justification .-........................

By- -------- .By ..........................

. . .. .. .

Distribution I

A'vailability Codes

Avail and I orDist Special

Final reportApproved for public release; distribution is unlimited

DTIC QUALI INSPEOYED 3

Prepared for U.S. Army Engineer District, VicksburgVicksburg, MS 39180-6190

m4

US Army Corpsof Engineers N

Waterways Experiment

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Waterways Experiment Station Cataloging-in-Publication Data

Ulopis, Jos6 LIn situ geophysical investigation of the pile test section, Sardis Dam,

Mississippi / by Jos4 L. Uopis ; prepared for U.S. Army Engineer District,Vicksburg.

68 p. :iii. ; 28 cm. -- (Technical report ; GL-94-1)Includes bibliographic references.1. Dams -- Earthquake effects -- Testing. 2. Dams -- Mississippi --

Sardls. 3. Earthquake hazard analysis. 4. Soil surveys -- Geophysicalmethods. I. United States. Army. Corps of Engineers. Vicksburg Dis-trict. II. U.S. Army Engineer Waterways Experimnent Station. Ill. Title.IV. Series: Technical report (U.S. Army Engineer Waterways ExperimentStation) ; GL-94-1.TA7 W34 no.GL-94-1

Contents

P f e .......................................... iv

Conversion Factors, Non-SI to SI Units of Measurement ............ v

1-Introduction ...................................... 1

Background ...................................... 1Site description ................................... 2

General site description ........................... 2Pile test section ................................ 3

2-Geophysical Test Principles and Field Procedures ............... 4

Crosshole tests .................................... 4Downhole tests .................................... 6Surface vibratory tests ............................... 6

3-Test Results ...................................... 8

Crosshole tests .................................... 8Downhole tests ..................................... 8Surface vibratory tests ............................... 9

4-Summary ........................................ 12

References ........................................ 13

Figures 1-48

SF 298

III

Preface

A geophysical investigation was conducted at Sardis Dam, Sardis, Missis-sippi, by personnel of the U.S. Army Engineer Waterways Experiment Station(WES), during the periods 14-19 August, 23-26 September and 16-20 Decem-ber 1991. The work was funded under the Repair, Evaluation, Maintenanceand Rehabilitation (REMR) work unit entitled "Assessment of Requirementsfor Seismic Stability Remediation" and under the U.S. Army Engineer Dis-trict, Vicksburg (LMK) Sardis Dam remediation study. Mr. Wayne Forrest,LMK, was overall project coordinator.

Mr. Josd L. Llopis of the Engineering Geophysics Branch (EGB), Earth-quake Engineering and Geosciences Division (EEGD), Geotechnical Laborato-ry (GL), WES, was the Project Engineer for this phase of the study. Theoverall Project Engineer was Mr. Richard H. Ledbetter, Earthquake Engineer-ing and Seismology Branch (EESB), EEGD. The field work was performedby Messrs. Josd L. Llopis, Thomas B. Kean H, and Thomas Harmon, EGB.Dr. Janet E. Simms, EGB, assisted in the data reduction and analysis of thestudy. Messrs. Selymn W. Guy and Leo V. Koestler M of the Data Acquisi-tion Section,lnstrumetation Services Division, provided instrumentation sup-port. Messrs. Dennis Beausoliel and Frank James of the Operations Branch,Engineering and Construction Services provided technical and logistical sup-port. Mr. Sam Stacy, LMK, provided invaluable technical support during sitepreparation phase of this study.

The work was performed under the direct supervision of Mr. Joseph R.Curro, Jr., Chief, EGB, and under the general supervision of Drs. A. G.Franklin, Chief, EEGD, and William F. Marcuson MI, Chief, GL.

At the time of publication of this report, Director of WES was Dr. RobertW. Whalin. Commander was COL Bruce K. Howard, EN.

iv

Conversion Factors,Non-SI to SI Units ofMeasurement

Non-Si units of measurement used in this report can be converted to SI unitsas follows:

Multiply By To Obtain

degrees (angle) 0.01745329 radians

feet 0.3048 moetrs

feet per second 0.3048 meters per second

gallons 3.785412 cubic deoimeters

Inches 2.54 continetero

kips (force) 4.448222 kilonewtons

miles (US statute) 1.609347 kilometers

pounds (force) 4.448222 newtons

pounds (mass) 0.4535924 kilograms

square miles 2.589998 square kilometers

V

1 Introduction

Background

The U.S. Amy Engineer District, Vicksburg (LMK) has undertaken sever-al studies to evaluate the probable behavior of Sardis Dam, S&,dis, MS duringand after an earthquake. The studies were conducted because of concernsabout the stability of the dam under seismic conditions and the possibility ofliquifaction of portions of the dam and its foundation. Results of the investi-gation have concluded that some modifications should be made to the dam toimprove its stability. relative to seismic loading. One remedial measure that isbeing considered to increase soil stability is to drive prestressed concrete pilesthrough weak layers of the dam and into stronger layers below. The piles aredesigned to restrain large flow deformations and have the additional benefit ofdeasifying the surrounding soil. A pile test section was constructed on thedownstream toe of the dam to evaluate this method of remediation.

As part of the ongoing LMK Sardis Dam remediation study and as a partof the Repair, Evaluation, Maintenance and Rehabilitation (REMR) work unitentitled "Assessment of Requirements for Seismic Stability Remediation" per-sonnel of the US Army Waterways Experiment Station (WES) conducted ageophysical investigation at the pile test section at Sardis Dam. The objectiveof the geophysical investigation was to assess soil strength changes due toremediation efforts at the test section.

"The remediation technique testing consisted of driving 16- to 24-in. squareprestressed concrete piles into the test section. To determine the possible den-sification effects of this remediation measure, crosshole shear-wave (S-wave),downhole S-wave and surface vibratory tests were conducted prior to, imme-diately after, and 3 months after pile driving activities. The S-wave velocityis used in determining the shear modulus of the soil. The equation relatingS-wave velocity to shear modulus and density is:

V-

whereV. = S-wave velocityG = shear modulusp = density

While the S-wave velocity is directly related to shear modulus seems naturalenough, the inverse relationship to density seems to be contrary to intuition.The S-wave velocity usually increases in spite if an increase in density notbecause of it. The same factors which increase density also decrease porosityand thus increase the shear modulus.

Site description

General site description

Sardis Dam is located in northwestern MS approximately 60 mi. south ofMemphis, TN and 10 mi. southwest of the town of Sardis, MS as shown inFigure 1. The dam was constructed on the Little Tallahatchie River, and con-trols flow from 1545 mi? of drainage area. The reservoir has a surface areaof about 14 mi2 at minimum pool (conservation pool). Conservation pool ismaintained at El. 236.0 ft. National Geodetic Vertical Datum (NGVD) (U.S.Army 1985).

The dam is composed of a main embankment, abutment dikes, spillway,and outlet works. The main dam has an approximate length of 8500 ft. Thecrown width is approximately 40 ft. wide at the dam crest. The maximumheight of the dam above the streambed is 117 ft. (U.S. Army 1985). Figure 2shows a typical cross section of the dam.

Sardis dam is a hydraulically placed embankment consisting of a finegrained central core and two flanking sand shells. The construction methodthat was used is demonstrated in Figure 3. Material from a nearby borrowarea was pumped into the zone between the downstream and upstream shells.The finer grained material (mostly silt) flowed toward the center and formedthe central core whereas, the coarser material was deposited near the fill pipeand formed the shells. The colloidal fraction of the effluent was drained offto a disposal area (U.S. Army 1985).

The dam's foundation consists of Recent and Tertiary aged deposits. Ageneralized geologic profile is shown in Figure 4. The foundation has a 10 to20-ft thick zone of natural silty clay, designated as the topstratum clay in Fig-ure 4 and extends 1200 ft upstream of the dam centerline. In areas of theoriginal streambed the topstratum clay was nonexistent and a 10-ft thick silty

2

clay roiled fill was placed in this area. The toptratum clay is underlain bypervious alluvial sands (substratum sands) which are approximately 40 ft thickand underlain by Tertiary silts and clays. During the dam construction, thetopstratum clay was removed from beneath the downstream portion of the damto help control under seepage (U.S. Army 1988). Loess deposits of Recentage cap the higher elevation abutments.

Pile test section

The pile test section, located on the downstream toe of the dam, was levelwith surface elevations ranging between approximately 223 and 224 ft(Figure 5). Boring information from the test site indicated that the upper 5 ftof each boring consisted of silty sand, silt or clay fill materials. Underlyingthe fill material and extending to depths of approximately 45 to 50 ft are fineto medium grained sands with occasional clay strata and lenses. Tertiary agematerials underlie the sand sum. These materials are best characterized asstiff lean clay with silty sand strata.

The main pile test section, located between Sta. 44+30 and 45 +78, wasdivided into 3 test sections referred to as Pile Groups A, B and C (Figure 6).Square, 24-, 20-, and 16-in prestressed concrete piles were driven into PileGroups A, B, and C, respectively. Spacings between piles for each pile groupand the pile driving pattern are shown in Figure 6. The piles were 55 ft inlength and were driven such that the tops of the piles were slightly below theground surface. The pile tips were driven slightly into the Tertiary materials(tip elevation approximately 168 ft).

3

2 Geophysical Test Principlesand Field Procedures

As mentioned earlier crosshole S-wave, downhole S-wave, and surface vi-bratory tests were run to ascertain S-wave velocity changes in the pile testsection. The tests were run to determine velocity changes as a function ofdepth and time. The general location and layout of the geophysical tests areshown in Figure 7. The geophysical survey procedures, including a briefdescription of each survey as it pertains to this investigation are given below.Further information regarding geophysical testing and intepretation proce-dures used in this study is given in Engineer Manual EM 110-1-1802 (Depart-ment of the Army 1979).

Crosshole tests

Crosshole tests were run to determine horizontal S-wave velocities as afunction of depth. The location of the four borings used for crosshole testingare shown in Figure 7. An advantage of the crosshole test as opposed to sur-face seismic refraction test is its ability to detect low velocity layers underly-ing or sandwiched between layers of higher velocity. One shortcoming of thecrosshole method is that boreholes are required for testing. Thus, crossholetests seismic tests are more costly than a surface seismic refraction test. How-ever, the crosshole technique is considered to be more definitive and accuratethan the surface seismic refraction test for measuring S-wave velocities. Basi-cally, the testing consists of measuring the arrival time of an S-wave that hastraveled from a source in one borehole to a detector in another borehole at thesame elevation. This procedure is then repeated for the next test elevation.Knowing the distance between borings and the time the S-waves take to travelacross this distance the velocity can be computed (distance divided by time).

The borings used for the crosshole testing were drilled to a depth of 55 ftwith a diameter of approximately 6.5 to 7 in. The borings were then casedwith 4-in inside diameter (ID) Schedule 40 polyvinyl chloride (PVC) casingand capped at the bottom. The annular space between the casing and thewalls of the boring were grouted with a material that approximated the densityof the surrounding in situ material. In this case, a mixture obtained by mixingI lb. of bentonite and 1 lb. of portland cement to approximately 6.25 lb.

4

(0.75 gal.) of water. The grouting was carried out in one continuous opera-tion, filling the annular space between the drilled hole and the casing with atremie pipe, from the bottom of the borehole to the surface.

Borehole deviation (drift) surveys were conducted to determine the precisevertical alignment of each boring. Figure 8 shows the deviation probe andinstumentation used to conduct the borehole deviation surveys. The incre-mental borehole deviation for each elevation along with the total deviation forthe boring are indicated on the control panel. A borehole deviation surveywas performed for each site visit. Accurate reduction of data from the cross-hole tests requires knowledge of the drift of each boring so that a straight-linedistance between borings at each test depth can be established. An analysis ofthe croashole data obtained at each test elevation was made with the aid of thecomputer program CROSSHOLE developed at WES (Butler, Skoglund andLanders 1978).

S-wave velocities were obtained by placing an S-wave source in a sourcehole and detectors, at the same elevation, in two other boreholes (receiverholes). The detectors consisted of a triaxial array of geophones (two mountedhorizontally at 90 deg. to each other, and one vertically oriented) in one con-tainer. The container housing the geophones was clamped firmly to the casingwall by means of an expanding pneumatic piston. A downhole vibrator wasused as a source of S-waves. The S-wave testing procedure consisted of low-ering the vibrator in the borehole to a selected test elevation and clamping thevibrator firmly to the sidewalls of casing by means of an inflatable rubberbladder. When the vibrator was in position, the operator tested a range offrequencies (50 to 250 Hz) and selected one that propagated well (one with ahigh amplitude) through the transmitting medium. The time required for theS-wave to travel from source to receiver hole was recorded using a portable,24 channel seismograph with data-enhancement capability. Figure 9 illustratesthe crosshole S-wave technique.

The data was collected by selecting one boring as the source boring andtransmitting the signal to two receiver borings. When the data collection wascompleted for these hole sets, the source was placed into the next hole and thenext two borings used as receiver holes. This process was repeated until eachboring was used as a source hole. The source-receiver configuration used forthis project is presented in Table 1. This testing configuration allowed a reci-procity check between hole set 1 and 3 and hole set 2 and 4. This testingpattern was repeated on each successive site visit. It is noted that neither thevibrator nor the geophones could be lowered past a depth of 45 ft. in hole 4for either the second or third trips; apparently the casing was disturbed insome manner during the pile driving operations.

5

Table ISource and receiver boring pattern for S-wavecroashole tests

ftura* boiho Roekwv bodg oiw .,n

1 2 3

2 3 4

3 4 1

4 1 2

Downhole tests

Downhole tests were conducted by placing an S-wave energy source on theground surface close to the mouth of a borehole, and a triaxial array of geoph-ones placed in the borehole. In this type of survey the travel path of seismicsignal is forced to traverse all of the strata between the source and detector.The downhole test also has the ability to detect inversion layers and therefore,complements the crosshole test. An illustration of the downhole S-wave tech-nique is shown in Figure 10.

The survey is conducted by impacting one end of a large wooden plank lo-cated on the ground surface near the mouth of a borehole with a sledgeham-mer and measuring the time the seismic disturbance takes to travel from thesource to the triaxial array of geophones in the borehole. Before moving thegeophone to the next elevation the test is repeated however, the plank is struckon the opposite end thus, reversing the polarity of the S-wave. By striking theboard on opposite ends and reversing the polarity of the generated S-waves,the arrival time can be determined by identifying on the record where the twosuccessive wave forms separate or change polarity as depicted in Figure 11.This procedure was repeated at 5 ft depth increments for each borehole shownin Figure 7.

Surface vibratory tests

The location and layout of the two surface vibratory tests run at the site areshown in Figure 7. These tests were conducted to determine the Rayleigh-wave (R-wave) velocity of the materials comprising the three pile groups anda region outside the test area (baseline). The R-wave velocity is slightly lowerthan the S-wave velocity, in fact for homogeneous media and for Poisson'sratios commonly found in soil materials, the difference in velocities is lessthan 9 percent (Ballard 1964 and Vrettos and Prange 1990).

The test is conducted by generating a discrete frequency waveform on theground surface and measuring the phase velocity with a line of geophonesplaced on the ground surface. The R-waves for this investigation were gener-ated by a truck mounted vibrator as shown in Figure 12. The vibrator truck

6

uses an electro-hydraulic vibrator with a maximum force output of 20 kips.The test procedure consisted of laying out a straight array of geophones andpositioning the truck at an offset location which was in line with the geophonearray. The offset distance was determined by the frequency and the forcelevel of the vibrator. The vibrator was then operated at discrete selected fre-quencies (5-90 Hz) with the R-waves being monitored by the geophones (thegeophone nearest the vibrator served as zero time). At lower frequencies arelatively large offset was used to allow sufficient distance for the waveformto develop whereas, at higher frequencies, where the vibrator output force islower, a smaller offset distance was employed. Offset adjustments were som-etimes necessary to reduce the effects of signals arriving along unwanted paths(e.g. reflected and refracted paths). The geophone array incorporated 24 geo-phones with spacings of 5 and 10 ft.

The time of arrival (referenced to the zero geophone) of a particular eventat each geophone in the array was measured and plotted versus the respectivedistances of the geophones from the reference geophone. The R-wave veloci-ty for each frequency was determined from the slope of the best-fit line ob-tained for the plot. Knowing the frequency and the R-wave velocity, a corre-sponding wave length was computed by dividing the velocity by the frequen-cy. Wave velocities thus derived are assumed to be average values for aneffective depth of one-half the wavelength. The R-wave data collection andreduction techniques are illustrated in Figure 13.

7

3 Test Results

Crosshole tests

"The CROSSHOLE program results for the crosshole tests conducted duringtrips 1, 2 and 3 are presented as plots of velocity versus depth as shown inFigures 14 through 16, respectively. The velocities obtained for each boringset during trip 1 (Figure 14) agree very well with the exception of the upper15 ft. The velocity discrepancy between boring sets in the upper 15 ft is pro-bably due to the inability to accurately pick the time of arrival of the S-wavebecause of signal attenuation through the loose soil (fill) in this depth interval.Velocity agreement between boring sets for trips 2 and 3 (Figures 15 and 16)are also very good. It is noted that the velocities measured between borings 4and 1, indicated in Figures 15 and 16 by the filled circles, are significantlyhigher than the velocities for the other borehole sets. The pile, located be-tween borings 1 and 4 (Figure 17), has a marked effect on the surroundingsoil as illustrated by the high S-wave velocity between these two borings. Theincreased S-wave velocity between these borings was presumably chieflycaused by the densified soil surrounding the pile rather than the pile itself.Based on an S-wave velocity for concrete of 8000 fps (Rix 1988) the time foran S-wave to travel trough a 24-in concrete pile would be approximately 0.25mrse, a very small fraction of the average travel time of 13.5 msec.

Average velocity profiles were determined for the three trips and areshown in Figure 18. The Figure 18 shows that the post-treatment velocitiesare considerably higher than the pre-treatment velocities. It is noted that thevelocities obtained from crosshole tests conducted between borings 4 and 1were not used to determine the average velocity profiles for trips 2 and 3(post-treatment).

Downhole tests

"The results of the downhole tests obtained during the three site visits arepresented in Figures 19 through 30. Tle plots are presented as time versusslant distance. The slant distance is the distance from the source to the receiv-er and for depths greater than 20 ft, depth and slant distance are approximate-ly equal. A summary of the downhole test results for trips 1, 2, and 3 arepresented in Figures 31 through 33, respectively. Figures 31 through 33

8

show that for a given trip the downhole S-wave velocities agree very wellbetween borings. Figure 34 presents the average downhole velocities for theeach of the three trips. The results indicate basically two velocity layers withthe layer interface occurring at an approximate depth of 30 ft. Referring toFigure 34 it can be seen that the average velocities for trip 1 are lower thanthose for trips 2 and 3 however, they are not considered significantly lower.Thus, it can be concluded that no significant S-wave velocities differenceswere noted between pre- and post-treatments using the downhole testing meth-od.

Surface vibratory tests

The vibratory tests were analyzed basically in two ways in an attempt todetermine differences in soil velocity caused by the pile driving operations.The first method consisted of determining the R-wave velocity for each pilegroup as a function of time (for each trip). This was accomplished by analyz-ing the vibratory signal over a particular pile group to determine that group'sphase velocities. Plots of velocity versus depth for the pile groups and back-ground area were generated. The plots of velocity versus depth over each pilegroup as a function of time for Line 1 are presented in Figures 35 through 38whereas, the plots for Line 2 are shown in Figures 39 through 42.

To assess the effects of the treatment on a particular pile group velocity, ananalysis of variance (ANOVA) was performed. Duncan's new multiple rangetest (Dowdy and Wearden 1913) at the 95 percent confidence level was usedto determine if there was a significant difference between the pre- and post-treatments average velocities for each pile group and background area. Theresults of the analysis are presented in Table 2.

Table 2 indicates that the Line 1 velocities in Pile Groups A, B, and Cexperienced a significant increase between the pre- and post-treatment. PileGroups A and C showed no significant difference in velocity between trips 2and 3. However, there was an unexplained significant increase in velocitybetween trips 2 and 3 in Pile Group B. There were no significant velocitydifferences for the background area, as would be expected.

Line 2 showed a velocity increase over Pile Group A between the pre- andpost-treatment. No significant velocity change was noted in Pile Group B.The placement of Line 2 was planned such that it would run along the top of aline of piles on the downstream edge of Pile Group B. It is possible that theline totally missed the pile group thus, possibly explaining the lack of a differ-ence in velocities between trips. Line 2 did not actually pass over Pile GroupC so no difference in velocity should be expected and the data confirm thisassumption. As was the case for Line 1, Line 2 showed no velocity differenc-es for the background materials.

9

Table ISumnmary of ANOVA determnations for R-wave velocities, fps

Velloaes with sooummn -un1 -ln An- w not differen at 916% Rofdenoe detnednisd byDunsen's now nvddpbe ranW %w

Line IULne 2

P1 Growup Trip Number Pe Group Trip Number

A (24 in.) 1 2 3450 678 Z 97 518 639 667

B (20 In.) 1 2 3 B' (20 in.) 1 2 3499 586 663 582 586 648

C (16 in.) 1 3 2 C' 016 In.) 2 1 3501 617... 551 557 558

Background 1 2 3 Background 2 3 1513 542 542 534 541 572

Vibratory line 2 passed over the edge of Ple Group B (refer to FIgure 7)Vibratory line 2 did not pms over Pile Group C (refer to Figure 7)

Using the same ANOVA method employed above, vibratory Lines 1 and 2were analyzed to determine how the R-wave velocity differed as it traveledacross the different test sections and background materials for a given trip.The velocity versus depth plots for Lines I and 2 are presented in Figures 43through 49. The results of the analysis are presented in Table 3.

"ITe ANOVA results for Lines 1 and 2 indicate no velocity differences be-tween the pile groups and the background area prior to pile driving activities(Trip 1). The data for Line 1 - Trip 2, indicates that the background velocitywas significantly less than the velocity for Pile Group C but not different thanthe velocities of Pile Groups A and B. The data also demonstrate that thevelocities between pile groups are not different for Line I - Trip 2. The anal-ysis of Line 1 - Trip 3 shows that there is no difference between the back-ground and Pile Groups A and C and no difference between Pile Groups Cand B. Pile Group B showed a significantly higher velocity than those mea-sured at Pile Group A or in the background area.

The analysis of Line 2 - Trips 2 and 3 indicate the same general trend thatis Pile Groups C and B and the background materials had no significant differ-ences in velocity. Also, Pile Group A and B had similar velocities. Again, itis noted that Line 2 passed near Pile Group C but not over it as shown in Fig-ure 7. The order of velocities, from high to low, for Line 2 - Trips 2 and 3was Pile Group A > B > C > background. It is noted again that Line 2 didnot pass directly over Pile Groups B and C. The order of the velocities corre-sponds with the proximity of the Line 2 to the Pile Groups. In general, thecloser the line is to a pile group the higher the velocity.

10

From a statistical analysis, the vibratory method was able to distinguish achange in soil velocity due to the installation of the piles. One of the objec-tives of the vibratory test was to determine if the pile group velocity was af-fected by the pile size and spacing. Based on the ANOVA, it appears that thevibratory tests do not correlate velocity with pile group.

Table 3Summary of ANOVA determinations for averageR-wave velocities, fps

Veloakia. with oommon undinnbd are not different at 96% oonfidenoe s deteamdned byDunman'e new multiple range test

Line Ikie 2

Trip TripNumber Poo Group numb, Pie Group

1 A B C BG 1 A C BG B450 499 501 513 518 557 572 582

2 BG B A C 2 BG C B A542 586 597 621 534 551 586 639

3 BG A C B 3 BOG C B A542 578 617 663 541 558 646 667

Note: BG denote. background

11

Summary

This report documents the results of an in situ geophysical investigationconducted at the pile test section located on the downstream toe of SardisDam. The purpose of the investigation was to determine which, if any, of thegeophysical tests used could detect any soil property changes as a result ofdriving piles in the test section. The three geophysical tests conducted used atthe site were the crosshole and downhole S-wave tests and surface vibratorytest. Tests were conducted prior to, immediately after and 3 months afterpiles were driven.

Of the three geophysical techniques tested at the site, the crosshole S-wavetest showed the greatest velocity difference between the pre- and post-treat-ment. No significant velocity differences were noted using the crosshole testbetween Trips 2 and 3. The interpretation of the downhole S-wave tests failedto exhibit any significant velocity differences between borings for a given tripor any velocity differences between trips. An ANOVA technique was used toanalyze the surface vibratory data. The analysis showed that, in general, therewas a significant velocity increase between the pre- and post treatments forthose sections of the vibratory lines passing directly over a pile test section.No conclusions could be made regarding the effects of pile group spacing onvelocity.

12

References

Ballard, R. F., Jr. (1964). "Determination of soil shear moduli at depths byin situ vibratory techniques," Miscellaneous Paper 4-691, U.S. Army Engi-neer Waterways Experiment Station, Vicksburg, MS.

Butler, D. K., Skoglund, G. R., and Landers, G. B. (1978). "CROSSHOLE:An interpretive computer code for crosshole seismic test results, documen-tation, and examples," Miscellaneous Paper S-78-8, U.S. Army EngineerWaterways Experiment Station, Vicksburg, MS.

Department of the Army (1979). "Geophysical exploration," Engineer ManualEM 1110-1-1802, Office of the Chief of Engineers, Washington, D.C.

Dowdy, S. and Wearden, S. (1983). Statistics for research. John Wiley &Sons, New York.

Rix, G. J. (1988). "Experimental study of factors affecting the Spectral-Analysis-of-Surface-Waves method," Ph.D. diss., University of Texas,Austin.

U.S. Army (1985). "Sardis Dam earthquake study, Design MemorandumNo. 5, earthquake resistant remedial measures design for Sardis Dam,Sardis, Mississippi," U.S. Army Engineer District, Vicksburg, MS.

(1988). "Sardis Dam earthquake study, SupplementNo. I to Design Memorandum No. 5, earthquake resistant remedial mea-sures design for Sardis Dam, Sardis, Mississippi," U.S. Army EngineerDistrict, Vicksburg, MS.

Vrettos, C. and Prange, B. (1990). "Evaluation of in situ effective shearmodulus from dispersion measurements," Journal of Geotechnical Engi-neering 116(10), 1581-85.

13

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a .... a..... ............... . ® ® ® ®®a®*aaI i' : I' ' OIR[CTIIOI Frml VaOIaC•

a OF INSTALLATION.

a *aOlWC~Io, Fm I~ra*rEL a

OF INSTA.LATION.

e Group A Pile Group B Pi

stressed concrete piles 20-in square prestressed concrete piles 16-in square pr,

Figure 6. Location and layout of pile groups A, B, and C

29 MIA i , , , ,1 1 | ,is, ,O M OIESIES

...... ;• . . ..

2S* sin:.i 's'~o------ -- -E. :-I

id N . ..

~~~~~~N .. . .. . .. .O-= .Pil Grup PiLe Gru C cIP5.

Pilgous÷, B, an C

, , , i'-E -- 1 - -i J hi ma a a aa a a. .aa...a"I S a.a a a a- a a a a. -,.a .-

a a ® ÷aaa a_ aIq"0 F~ $( IJ[ aat a • I T a aL a a.

a a a a a-:a, a.a.a. a. ,I a . ,• ,..

pil grup A, B, in a -

07. SOA PRETRESE

CONCAVE VILE.

------- ----------------------------------

, A , -,---'--OFI I AT ION.

F I I I I I I

• i i i i

*1: * -- .g : . . . .64 * *. I -7 -r--''=

, .. ..I I i , I '

, ÷ .eFigure.7. ®o®ati-

20, SOLW PJSTWSIED0 CONCRET PILE.

-- -- -- - ----- I -- - .

a Lin i i a a a I i jI , a aaI III

---....... -. ......... --". .. ....... . -- ---- -

---- r ---- R-wave Line2

: .' * 1r .. - '-"- S'o 'o s'-ra a'o a s.--o" •I

.. iR-wave Line1 2 . . . .a )''

i $llCl• 8 6a a IOF IaTAi.,OIT Iaa N• i O_ a I a

.. o . . I.

a TITM".T

' ' '-• ,.,•.,-.,-

"iu .o i

Figure 7. Location and layout of geophysical tests

MA WUETAn is- S~MO PSWSSMEMMII PILE. [ CONTE FILE.

80 lftm - -- - - - -- -_ _ _

S. -a S. S.-F. E A

II M M Fm I I I *U

*~~O 4 *I S I I I S V '

~ vIc mts -*II

a. Deviation probe being lowered into boring

b. Surface control unit and winch

Figure 8. Borehole deviation tool

00

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22

0 75

IA 0 w

zz

a0 0 ILm

o i

LU cc0 0U

zz

00

DMH S-WAVE BORING #3 D 4OFT

,I i

a. Downhole S-wave record obtained from stiking the east end of the board

'Ij!iI

III 2 k!iIi

b. Downhole S-wave record obtained from stiking the west end of the board

Figure 11. Example of downhole S-Wave trace reversals obtainedby striking opposite ends of board

I.�4)

0

00b...0

0'I(U

(U

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S~Geophones

a. Vibrator exciting the ground surface

a) CD

C O ) 5 oe1~00

0 '10

T Ime T i!me -.

b. Geophone traces c. T-D plot

where:

X - wavelength

V - velocity

f - frequency

I depths- R& X2

-C

Ve I oc i. t y

d. Velocity versus depth plot

Figure 13. Surface vibratory data reduction procedure

00000000

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co

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11'-CdC

Time, msec0 10 20 30 40 50 60 70 80 90 100 110 120

10

-20-

25-

0

50 -

60- 4

TRIP 1 - DOWNHOLE S-WAVEHole 1

Figure 19. Downhole S-wave velocity versus depth, Trip 1, boring 1

Time, msec0 10 20 30 40 50 60 70 80 90 100 110 120

5I0

10-

20 -

25-

-+ 30--

c 35 --

40-

0)0

-45-

50-

55-

60- I ,, ,

TRIP 1 - DOWNHOLE S-WAVEHOLE 2


Time, msec0 10 20 30 40 50 60 70 80 90 100 110 120

0- 1

10

15-S20 -

025-

-0-030-

C 40-

0f 45 -

65-

60 -,


Figur 21. Downhole S-wave velocity versus depth, Trip 1, boring 3

Time, msec0 10 20 30 40 50 60 70 80 90 100 110 120

0.

5-

100

15-

""20-

L 25-

035430

(I)%s-__ 0(.f)45- *

50-*

55-

60- 1 1 7 7 1 1 1 - - 1 1 1 1 1


Figum 22. Downhole S-wave velocity versus depth, Trip 1, boring 4

Time, msec0 10 20 30 40 50 60 70 80 90 100 110 1200 -I I I I i I i I I I I I I I I I

10

15-10-

20

L25-c

30

35-

C 40 \(/)45-

5o-

55-

60-



Time, msec0 10 20 30 40 50 60 70 80 90 100 110 1200 - i I I , I , I i I i I i I I i I I , I i

5-

10

15 "

20--

()25-

.430-

035-40-

5

%45

50 *

55-

60-



Time, msec0 10 20 30 40 50 60 70 80 90 100 110 1200 - ; I I I , I I , I I I I , I i I I , I , I

105-

10 - i

20-

25-

~.630-Cn

035

40-

(/)45-

55-

6 0 1 i l I I I I I I I -I I


Figure 25. Downhole S-wave velocity versua depth, Trip 2, boring 3

Time, msec0 10 20 30 40 50 60 70 80 90 100 110 1200 - , I n I i I I I nI I I i I I I , I

5-

10- Itl.

15-

S20-

0 25-*

0 35-

0

(/)45-

050-

55-

6 0 1 1 T I T I I I I I I T I I T I I I



Time, msec0 10 20 30 40 50 60 70 80 90 100 110 1200 - I I a I i I i I i I i I I I 1 I

5- *

10-

15-

20-

•25-

0•30-

40-C 40-

50-

55-

60- r


Figur 27. Downhole S-wave velocity verms depth, Trip 3, boring 1

Time, msec0 10 20 30 40 50 60 70 80 90 100 110 120

10

2013-

40

25 -

0

T 35-

cHOLE 2

F- T

(/)45-

55-

603-



Time, msec0 10 20 30 40 50 60 70 80 90 100 110 120

0- I I I I

5-

10-

15

S20

-j.-30--i1)

0035*

C 40-

(/4550-

55-

60-


Qur- 29. Downhlh S-wa vWocity versus depth, Trip 3, boriv 3

Time, msec0 10 20 30 40 50 60 70 80 90 100 110 120

10-

15-

'"20-

25-

.j-30-

0- 40

V) 45-

50-

55-

60- I



To" To- C*ICI i qq 11

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ac 0

isi0L 0

50) 0&

CoC

m - 0

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00

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m C4

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o o

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mxA It, 0

0> Itilds

VIBRATORY TEST24-in. PILE TEST SECTION

0 - I I I I I I I I I I I I I I I I I I I I

10- •*0 0

20- o.0*O 0 1? o3 0 0

30- o o

0 0 00

- 0 00-

70-0

80-

90•**** TRIP 100000 TRIP 2coooa TRIP 3

1 0 0 1- 1 1 1 1 , -" -'200 300 400 500 600 700 800 900 1000

Velocity, ft/sec

Figure 35. R-wave velocity versm depth, Line 1, 24-in pile tes section, Trips 1, 2, and 3

VIBRATORY TEST

20-in. PILE TEST SECTION0 -I I I I I I I I I I I I I I I I I I I I I i

10- *0, 00

0 020 00 0o0

30-030 -"

o 0

* 0

-i- 40 ,

("50

So0

70 0

so-80

90 ***** TRIP 100000 TRIP 200000 TRIP 3

10 0 - i , I I I r ' I 'I I I 1 1 1 1 , I

200 300 400 500 600 700 800 900 1000Velocity, ft/sec

Figure 36. R-wave velocity versus depth, Une 1, 204n pile test section, Trips 1, 2, and 3


0 - I I I I I I I I I I I I I1 I I I I I I I I I I

100

100

- Go20 0a

0J0* *

30

• 0

-- *40-

-C 500

S60-0 0

70 0

80

90 ***** TRIP 100000 TRIP 2

- 00000 TRIP 3

100 - 1 1 1 1 1 1 1 1 1 1 1 1 1 1200 300 400 500 600 700 800 900 1000

Velocity, ft/sec

Figure 37. R-wave velocity versus depth, Line 1, 16-n pile test section, Trips 1, 2, and 3

VIBRATORY TEST

BACKGROUND0 -I I | ! I l I I I I I I I I I I I I I I I

10 0

10 0 *

020o 0

00 0

30 0*0*00

S40S•10

0

s'o(-50

CL

a60 60

70

80

90 ***** TRIP 1ooooo TRIP 20o0o0 TRIP 3

1 0 0 I-1, i 1i 1I 1 1, i i i s 1 1 1 1 1 I I I I I 1

200 300 400 5oo 600 700 800 900 1000

Velocity, ft/sec

Figure 38. R-wave velocity versus depth, Une 1, background area, Trips 1, 2, and 3


0 - I I I I I I I I I I I I I I I I I I I I I I -

10 * 0

20 ,* 000 *

30- 0 0o

0

40- 0-- 40 a

Q4-

-,4-- 0

(.)in 60-

70- 0

80-

90- ***** TRIP 100000 TRIP 2cooao TRIP 3

100- i I I I 1

200 300 400 500 600 700 800 900 1000

Velocity, ft/sec

Figure 39. R-wave veloity versusedpth, Uns 2, 24-in pile tt sect, Trps 1, 2, and 3


10 0o , 0 a* *0

20* 0

0* 0 0

3000030-

* 0 0-t-- 40 - 0

460

700

80-

90- ***** TRIP 100000 TRIP 2

- cooo0 TRIP 3

1 0 0 - I' I I I I I I I I I I I Ii

200 300 400 500 600 700 800 900 1000Velocity, ft/sec

Figure 40. R-wave velocity versus depth, Una 2, 20-"n pile test section, Trips 1, 2, and 3


0 - t t I I I Ii I I t , i I I , I I I I, I I I I

10 0 0

20O* O 0 02,0

a 0 030 € 030- 000 0000 a 00

--- 4'40-

0*

..C50-4,--

~60

70

80

90•**** TRIP 100000 TRIP 200000 TRIP 3

200 300 400 500 600 700 8oo 900 1000Velocity, ft/sec

Rgure 41. R-wave velocity versus depth, Line 2, 16-in pile test section, Trips 1, 2, and 3

VIBRATORY TESTBACKGROUND

0 - I I I I I I I I I I I I I I I I I I I I I I I I

10 0

0 0 0* *0

20 0*o0 *0

300

*0

0-- 40-9--

-C 50-00*

i 60-

70

80

90 ***** TRIP 100000 TRIP 200000 TRIP 3

100-200 300 400 500 600 700 800 900 1000

Velocity, ft/sec

Figure 42. R-wave velocity versus depth, Une 2, background area, Trips 1, 2, and 3

VIBRATORY TESTLINE 1 - TRIP 1

0-

10

*0 00&0

20- o _

30-

4- 0t0S40- * *

0 0

S60-

70-

7 PILE TEST SECTION

S***** 24- in.00000 20- in.00000 16- Ln .

90- £AAA& Un d is t.

10 0 I' I I I I I I I I I

200 300 400 500 600 700 800 900 1000

Velocity, ft/sec

Figure 43. R-wave velocity versus depth, Line 1, Trip 1, pile test sections A, B, C, and background


0 - I I I I I I I I I I I I 1 I I I I I I I 1 I I I I I I I -

10- *Oo 0 -0 40 Ca

0 £4 * *30 o

200 0 0 £

2- 0A 0

304-

o0* 0

40-E~- a9. 0

C- 50 -0

9)m 60-

70-

80- PILE TEST SECTION24- Ln .

00000 20- Ln .90 00000 16- Ln .

A&&&& Un d Ls t

100 -iT

200 300 400 500 600 700 800 900 1000

Velocity, ft/sec

Fgure 44. R-wave velocity versus depth, Un. 1, Trip 2. pile test sections A, B, C, and background


0 -I I I I I I I I I1 I I I I1 I I1 1 1 I I I I

10 0*o 0 00

A 0 0

S* 0 00

4: A 0 0 •30 00• 0

04,-- 0 0

a)a-C.so- 0

0) 60- A A

70-

80- PILE TEST SECTIONS* **** 24- In00000 20- In.

90- aaao 16- in.AAAAA Un d Ls .

1 0 0 I I , I I I I I I I I I I I I I I

200 300 400 500 600 700 800 900 1000Velocity, ft/sec

Figure 45. R-wave velocity versus depth, Une 1, Trip 3, pile teat sections A, B, C, and background


0 - I I I I I I 1 1 I I I I I I I 1 1 I I

10- *o

20 a 0_£ 0

* 0 0 &

30-0

-- 40-

0

("50-

t:) 60 0*

70

80 PILE TEST SECTION***** 24- Ln .00000 20- Lnr.

90- 000oa 16- Ln .A&&&& Un d Ls t

100 - - I I , i200 300 400 500 600 700 800 900 1000

Velocity, ft/sec

Figure 46. R-wave velocity versus depth, Une 2, Trip 1, pile test sections A, B, C, and background


0- I I I I I I , I I II I I I I I1 I I I I I I I

0

10- & *0 &

* 02- a Q60 o& 0 0* o

30-

00 * *

70-*0

80 PILE TEST SECTION***** 24- In00000 20- Ln .

90- 00000 16- In .• •••• Un d Is t.

100- ' I I I i II 1

200 300 400 500 600 700 800 900 1000

Velocity, ft/sec

Figure 47. R-wave velocity versus depth, Line 2, Trip 2, pile test sections A, 8, C, and background


0 - I I I I I I I I I | t | | I I I I I I I I I t I -

10- 0

0 0

20- a no 0 * 0- AD 0 k

30- -

0 0

- 40 S 0o

-C 50-°'-0-

0~0

70 0

80 PILE TEST SECTION* **** 24- In00000 20- tn.

90- 00000 16- n.A&&&& Un d Ls t.

10 0 - , 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 ,200 300 400 500 600 700 800 900 1000

Velocity, ft/sec

Figure 48. R-wave velocity versus depth, Une 2, Trip 3, pile test sections A, B, C, and background

REPORT DOCUMENTATION PAGE I No. oo•7oIUPmvic rgeoing burden foe tha €odlectace @ mforrntan ai aitmate to avoerge 1 houl Se reepone, including the tame for reiewm•n inituctImfl. teeWChang euaiteng data _o.wcathwng an a'maegmm th e dat neede.,nd c€ tret'ng an re.aesn the. €oaectun Of Ifflnon lnd omnme qnt redal tai uden_ el te or an othe..apect.of-thatteucs. Df Informatao. mdvudang I oat for reducing thi burden, to wmhanqton emeealuerte lervaces. Ou•ctorate i nfonnauon Operatuon andRprti _Ug_ IS __•, • ,-on

Ceem lighway. SuSIe 1294. AItSSllAo V 3.N24 2 andlto ISI Office of Manaemlent a•nd Buget eperpworPeuto • prtct -- (07040 I),Wasago. OC 20503'1. AGENCY US'E ONLY (Leeve bS.n) I2. REPORT DATE 3. REPORT TYPE AND DATES COVEREDI January 1994 Final Report

4. TITLE AND SUBTITLE S. FUNDING NUMBERS

In Situ Geophysical Investigation of the Pile Test MIPR No. 5119Section, Sardis Dam, Mississippi RMPR NoG51

L AUTHOR(S)

Jos6 L. Llopis7. PERIFORMING ORGANIZATION NAME(S) AND ADORESS(ES) I. PERFORMING ORGANIZATION

U.S. Army Engineer Waterways Experiment Station REPORT NUMBER

3909 Halls Ferry Rd Technical ReportVicksburg, MS 39180-6199 GL-94-1

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORINGU. S. Army Engineer District, Vicksburg AGENCY REPORT NUMBER

Vicksburg, MS 39180-6190Office Chief of EngineersWashington, D.C.

11. SUPPLEMENTARY NOTES

This report is available from the National Technical Information Service,5285 Port Royal Road, Springfield, VA 22164

Ila. DISTRIUTION I AVAILABLITY STATEMENT 12b. DISTRIBUTION CODE

Approved for public release; distribution is unlimited

13. ABSTRACT (MAximum 200 word)An in situ geophysical investigation consisting of crosshole and downhole

shear wave (S-wave) and surface vibratory tests was performed at Sardis Dam,located on the Tallahatchie River in northwest Mississippi. The tests wereconducted in a pile test section at the downstream toe of the dam. The purposeof the investigation was to determine changes in S-wave velocities, which arerelated to soil strength, in the test section due to pile driving activities.

The tests were conducted prior to driving the piles, immediately after and3 months after the piles had been driven. The S-wave crosshole and surfacevibratory tests indicated a significant velocity increase due to the driving ofthe piles in the test section. The downhole S-wave test did not detect anysignificant velocity increases.

14. SUBJECT TERMS 15. NUMBER OF PAGESCrosshole Geophysics Sardis Dam 68Elastic waves Rayleigh waves Shear waves 16. PRICE CODE

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT

OF REPORT OF THIS PAGE OF ABSTRACT

Unclassified Unclasified INSN 7540-01-280-5500 Standard Form 298 (Rev 2-89)

Prescribed by ANSI Std Z39-1S298-102

Documents

In Situ Geophysical Investigation of the Pile Test Section ...crosshole method is that boreholes are required for testing. Thus, crosshole tests seismic tests are more costly than