8/13/2019 EM_1110-2-3506

1/159

CECW-EG

Engineer Manual

1110-2-3506

Department of the ArmyU.S. Army Corps of Engineers

Washington, DC 20314-1000

EM 1110-2-3506

20 January 1984

Engineering and Design

GROUTING TECHNOLOGY

Distribution Restriction StatementApproved for public release; distribution is unlimited.

8/13/2019 EM_1110-2-3506

2/159

DAEN ECE G

Engineer ManualNo. 1110-2-3506

D E P R T ~ E N TOF THE R ~

U. S. Army Corps of EngineersWashington, o. C. 20314

Engineering anrt DesignGROUTING T E C ~ N O L O G Y

~ 1110-2-3506

20 January 1984

1. Purpose. This manual provides technical cr i ter iR and g u i ~ a n c efor c i v i lworks grouting applicat ions. Information on procedures, materials , andequipment for use in planning and executing a ~ r o u t i ~ gproject i s included,and types of problems tha t might be solved by g r o u t t n ~are discussed. ~ e t h o d sof grouting tha t have proven to be effec t ive r e described and various typesof grouts and the i r proport ions are l i s t ed .

2. Applicabil i ty. This manual i s applicable to l l ~ i e l do p e r a t i n ~ac t iv i t i e s having c iv i l works responsibi l i t ies .

3. Discussion. Grouting in c i v i l works ac t iv i t i e s i s performed as: a) anincrement of p e r ~ a n e n tconstruction, h) a post-construct ion r e ~ e d t a ltreatment, and c) an increment r expedient construct ion r repai r.

FOR THE COMMANDER

Corps of EngineersStaff

8/13/2019 EM_1110-2-3506

3/159

DEP RTMENT OF THE RMYU S. Army Corps of Engineers

Washington D C 20314

Engineer ManuaiNo EM 1110-2-3506

CHAPTER 1.

Engineering and DesignGROUTING TECHNOLOGY

Subject

INTRODUCTION

Purpose and ScopeApplicabil i tyReferences

Changes

Table of Contents

General ConsiderationsTerminology

CHAPTER 2. PURPOSES ND LIMITATIONS OF GROUTING

CH PTER 3

PurposesLimitationsSelection of Methods of Treatment

GEOLOGIC CONSIDERATIONS FOR INVESTIGATIONND DESIGN

Rock TypesStructural GeologyGeohydrologyInvestigation MethodsTest Grouting

CHAPTER 4. PLANNING ND PROCEDURES

ConsiderationsPlanning ConsiderationsQuality ManagementGrout Hole Drill ingTypes of TreatmentGrouting MethodsFoundation Drainage

EM 1110-2-3506

20 arruanr 1984

Paragraph

1-11 21 3

1 41-51 6

2 12 22 3

3 13 23 33 43 5

4-14 24 34 44 54 64-7

Page

1-11-11-1

1-11-11-1

2-12-12 2

3-13 33 43 63-8

4-14 24 24-34 64-134-19

This manual supersedes EM 1110-2-3501 dated 1 Jul 66 and EM 1110-2-3503dated 19 Aug 63.

i

8/13/2019 EM_1110-2-3506

4/159

EM 1110 2 350620 an 84

CHAPTER 5.

CHAPTER 6.

CHAPTER 7.

CHAPTER 8.

CHAPTER 9.

Subject

GROUT MATERIALS

Grout MaterialsPortland Cement Grout MixturesSpecial Cements and MixturesMixture AdjustmentsChemical GroutsAsphalt GroutsClay Grouts

EQUIPMENTIntroductionDrill ing and Grouting EquipmentSpecial Monitoring Equipment

APPLICATION TO W TER RETENTION STRUCTURES

Concrete DamsEarth and Rockfi l l Dams

APPLICATION TO TUNNELS SHAFTS NDCH MBERS

General ApplicationsPurposes of GroutingApplications

APPLICATION TO NAVIGATION STRUCTURES

GeneralFoundation TreatmentRepairsGrout Curtain Through the Lock Area

CHAPTER 10. APPLICATION TO BUILDING FOUNDATIONS

GeneralPregrouting InvestigationSoil Stabil izationRock Foundations

CHAPTER 11. PRECISION ND SPECIALTY GROUTING

General StatementScopeApplications

Paragraph

5 15 25 3S 4S 5S 65 7

6 16 26 3

7 17 2

8 18 28 3

9 19 29 39 4

10 110 210 310 4

11 111 211 3

5 15 55 95 105 145 155 15

6 16 16 29

7 17 5

8 18 18 1

9 19 19 19 2

10 110 110 110 3

11 111 111 1

8/13/2019 EM_1110-2-3506

5/159

Subject

CHAPTER 12. PERFORMANCE OF WORK

General ConsiderationsContractsHired Labor

CHAPTER 13. FIELD PROCEDURES

General ConsiderationsDril l ing OperationGrouting OperationsCompletion of Grouting

CHAPTER 14. METHODS OF ESTIMATING

General ConsiderationsTest GroutingGrouting RecordsEvaluation of Exploration Borings

Unit Take EstimatesBid Items

CHAPTER 15. RECORDS ND REPORTS

GeneralRecords

APPENDIX A. REFERENCES ND BIBLIOGRAPHY

ReferencesBibliography

APPENDIX B. EXAMPLE: FIELD PROCEDURE FORCLARENCE C NNON D M

APPENDIX C. PRESSURE COMPUTATION SAMPLES

APPENDIX lJ. PHYSICAL CHARACTERISTICS OF SANDED GROUTS

EM 1110-2-350f,20 an 84

Paragraph

12-112-212-3

13-113-213-313-4

14-114-214-314-414-514-6

15-115-2

A 1A 2

12-112-112-1

13-113-113-313-9

14-114-114-114-514-114-2

15-115-6

A 1A 3

B 1

C 1

D 1

8/13/2019 EM_1110-2-3506

6/159

CHAPTER 1INTRODUCTION

EM 1110-2-350620 Jan 84

1-1. Purpose. This manual provides technical cr i t e r i a and guidance for c i v i lworks grouting applicat ions. Information on procedures, materials , and equipment for use in planning and executing a grouting projec t i s included, andtypes of problems tha t might be solved by grouting are discussed. Methods ofgrouting tha t have proven to be effective are described and various types ofgrout and t he i r proportions are l i s t ed . The manual discusses grouts composedprimari ly of cementitious suspensions and addit ives although other types arementioned.

1-2. Applicability-. This manual i s applicable to a l l f ie ld operat ing ac t iv it i e s r e s p o n s i ~ l efor the design and construct ion of c iv i l projects .

1-3. References. See Appendix A for l i s t of references.

1-4. Changes. Users of th is manual are encouraged to submit recommendedchanges or comments to lmprove i t Comments should be keyed to the speci f icpage, paragraph, and l ine of the text in which the change i s recommended. Reasons should be provided for each comment to ensure understanding and completeevaluation. Comments should be prepared using D Form 2028 RecommendedChanges to Publicat ions) and forwarded direc t ly to HQUSACE DAEN-ECE-G) W SH DC20314.

1-5. General Considerations. Grouting in c iv i l works ac t iv i t i e s i s performedas: a) an increment of permanent construction, b) a postconstruction remedial t reatment, and c) an increment of expedient construct ion or repai r.Examples of permanent construction are cur ta in grouting in the foundations for~ dam and ground s tabi l iza t ion of foundation materials for large buildings.~ x a m p l e sof postconstruction remedial treatment include grouting voids underconcrete s t ruc tures and reducing leakage through a dam foundation or abutment.

r o ~ t i n gi s used for both temporary and permanent treatments. I t should beconsidered in combination with other appropriate types of treatment for bes tresul ts . Other types of treatment may include excavation, compaction, concre te cutoff walls , s lurry t renches, impervious blankets , drainage blanketsand f i l t e r zones, r e l i e f wel ls , dri l led drains, sheet pi le cutoff , dental con-cre te , grouting and drainage tunnels and ga l l e r i e s , underpinning, and s t ruct u ra l foundations. Purposes of expedient grouting include repai r of roadwaysand cofferdams, and s tab i l i ty and groundwater control during construction.

1-6. Terminology.

a. Alkali-Aggregate Reaction. Chemical reaction in grout between alkal i e s sodium and potassium) from portland cement or other sources and cer ta inconst i tuents of some aggregates; under certain condit ions, deleterious expansion of the grout may resul t .

1-1

8/13/2019 EM_1110-2-3506

7/159

M 1110-2-350620 Jan 84

b. Aquiclude. A body of r e l a t ive ly impermeable rock or so i l t ha t i scapable of absorbing water slowly but funct ions as an upper or lower boundaryof an aquifer and does not t ransmit groundwater rapidly enough to supply a

well or spring.c. Aquifer. A stratum or zone below the surface of the ear th capable of

producing water as from a well .

d. Aquitard. A confining bed tha t re tards but does not prevent the flowof water to or from an adjacent aqui fer ; a leaky confining bed.

e. Area Grouting. Grouting of a shallow zone in a par t icular area t ha tu t i l i z e s holes arranged in a pat te rn or gr id . This type of grouting i s some-times re fer red to as blanket or consolidat ion grouting.

f . Bentoni te . A clay composed pr incipal ly of minerals of the montmoril

l on i t e group, charac te r ized by high adsorpt ion and very large volume changewith wett ing.

g. Blanket Grouting. As s ta ted in above.

h. Burst ing Pressure Grouting Equipment). The pressure a t which equipment becomes inoperat ive.

i . Cement Factor. Quantity of cement contained in a uni t volume ofgrout , expressed as weight or volume

j . Cementitious Factor. Quantity of cement and cementitious materialscontained in a un i t volume of concrete , grout , or mortar, expressed as weightor volume.

k. Circui t Grouting. Grouting in a continuous manner with a grout ci rcul a t i ng from the pump to the bottom of the zone to be t rea ted and back to thepump

1. Coefficient of Permeabil i ty to Water). As s ta t ed in ad below.

m Colloidal Grout. A grout t ha t has an a r t i f i c i a l l y induced cohesiveness, or the a b i l i t y to r e t a in the dispersed soli-d par t ic les in suspension;i . e . a grout mixture t ha t does not s e t t l e or bleed.

n. Consolidation Grouting. As s t a t ed in e above.

o. False Set . The rapid development of r ig id i ty in a freshly mixedgrout without the evolu t ion of much heat . Such r ig id i ty can be dispel led andp l a s t i c i t y can be regained by fur ther mixing without the addit ion of water.Premature s t i ffening, hes i t a t ion s e t , ear ly s t i f f en ing , and rubber se t areother terms t ha t r e fe r to the same phenomenon

1-2

8/13/2019 EM_1110-2-3506

8/159

EH 1110 2 350620 Jan 84

p. Final Set . A degree of s t i ffening of a grout mixture greater thani n i t i a l se t general ly s ta ted as an empir ical value indicat ing the time inhours and minutes t ha t i s required for cement paste to s t i f f en suff ic ient ly to

r e s i s t the penetrat ion of a weighted t e s t needle.q. Flash Set . The rapid development of r ig id i ty in a freshly mixed

grout usual ly with the evolution of considerable heat and r ig id i ty cannot bedispel led nor can p las t i c i ty be regained by further mixing without the addit ion of water; also referred to as quick se t or grab se t .

r . Free Water.influence of gravity.phrea t ic water.

Water tha t i s free to move through a so i l mass under theOther terms are gravitat ional water groundwater and

s . Grout. A mixture of cementitious or noncementitious mater ia l withor without aggregate to which su ff i c i en t water or other f lu id i s added to

produce a flowing consis tency.t Grout Placement. The introduction of grout by gravity or pressure

into voids; usual ly accomplished by grouting through pipes placed in themedium to be grouted or through dr i l led open boles penetrat ing the medium.

u. Grout Take. The volume of grout placed.

v. Heat of Hydration. Heat generated by chemical react ions of cementit ious materials with water such as t ha t evolved during the se t t ing and hardening of port land cement.

w Hydrofracturing. The fracturing of an embankment or undergrounds t r a t a by pumping water under a pressure in excess of the t ens i l e s t rength andminor pr inc ipa l s t r e s s .

x. Hydrostatic Head. The pressure produced by the height of a f lu idabove a given point .

y. I n i t i a l Set . A degree of s t i ffening of a grout mixture general lys ta ted as an empirical value indicat ing the time in hours and minutes tha t i srequired for cement paste to s t i f f en su ff i c i en t ly to r e s i s t the penetrat ion ofa weighted t e s t needle.

z. Neat Cement Grout. A f lu id mixture of cement and water or the hardened equivalent of such mixtures. Also ca l led neat s lur ry.

aa. Packers. Expandable mechanical or pneumatic devices used to sea l ahole or i so l a t e port ions of a hole.

ab. Perched Groundwater. Any groundwater separated by unsaturated rockfrom an underlying body of groundwater.

1-3

8/13/2019 EM_1110-2-3506

9/159

EH 1110-2-350620 Jan 84

ac. Perched Water Table. The water t ab le above an impermeable bed underl a in by unsaturated rock or so i l of su ff i c i en t permeabil i ty to allow movementof groundwater.

ad. Permeabil i ty Laboratory) to Water, Coeff ic ien t of) . The r a t e ofdischarge of water under laminar flow condit ions through a uni t c ross-sec t iona larea of a porous medium under a uni t hydraul ic gradien t and standard temperatu re condit ions, usual ly 20C.

ae. Pore Pressure. Stress t ransmit ted through the pore water waterf i l l i n g voids) . Also ca l led neut ra l s t r e s s and pore-water pressure .

af . Pressure Testing. Test performed to measure the ra te a t which watercan be forced into a hole under a speci f ic pressure.

ag. Pressure Washing. A process of washing between holes to remove mud

and loose mater ia l from cracks and seams in the rock. In effec t , i t i s as lu ic ing operat ion whereby water or a i r and water a l t e rna te ly are introducedunder pressure in to a hole and allowed to vent in to adjacent cracks or escapefrom one or more adjacent holes .

ah. Primary Hole. The f i r s t se r i e s of holes to be dr i l l ed and grouted,usua l ly a t the maximum allowable spacing.

a i Primary Permeabil i ty. The permeabil i ty of i n t ac t rock, ra ther thanpermeabil i ty due to f rac tur ing .

a j Primary Porosi ty. The porosi ty tha t develops during f ina l stages ofsedimentation or t ha t was present within the sedimentary par t i c l e s a t the time

of deposi t ion.

ak. Refusal . The point during grout in jec t ion when l i t t l e or no grouti s accepted under the maximum allowable pressure or other spec i f iedcondit ions.

a l Secondary Hole. The second se r i e s of holes to be dr i l l ed andgrouted, spaced midway between primary holes.

am Sect ion. A l i nea r or area l subdivision of the grout t reatment pa t - t e rn without regard to the depth of treatment .

an. Seep. n area where water oozes from the ear th .

ao. Ser ies Grouting. Similar to stage grouting, except each success ive lydeeper zone i s grouted by means of a newly dr i l l ed hole, e l imina t ing the needfor washing grout out before dr i l l i ng tbe hole deeper.

ap. Spl i t Spacing. The procedure by which addi t iona l grout i n j ec t ionholes are loca ted equid is tan t from previously grouted holes.

1-4

8/13/2019 EM_1110-2-3506

10/159

M 1110-2-350620 an 84

aq. Stage. A stage i s one complete operat ional cycle of dr i l l i ng ,cleaning, pressure washing, pressure tes t ing , pressure grouting, and groutcleanout within a zone. Depths of stages in any hole depend on conditions

encountered in dr i l l i ng tha t d ic ta te where dr i l l i ng should stop and grout ingcommence.

ar. Stage Grouting. The grouting of progressively deeper zones instages. Previously emplaced grout i s removed pr ior to hardening, the hole i sdr i l led to a deeper depth, and another stage i s emplaced.

as. Stop Grouting. The grouting of a hole beginning a t the lowest zone(bottom) a f t e r the hole i s dr i l l ed to t o t a l depth. Packers are used to i so-l a t e the zone to be grouted.

a t . Sulfate Attack. Harmful or deleterious react ions between sul fa tesin so i l or groundwater and grout.

au. Ter t ia ry Hole. The th i rd ser ies of holes to be dr i l led and grouted,spaced midway between previously grouted primary and secondary holes.

av. Thixotropy. The property of a material t ha t enables i t to s t i f f enin a shor t period, on standing, and to regain i t s i n i t i a l viscos i ty by mechani ca l agi ta t ion; the process i s revers ib le .

aw. Time of Set t ing .

(1) Final se t t i ng time. The time required for a freshly mixed grout toachieve f ina l se t (harden).

(2) I n i t i a l se t t ing time. The time required for a freshly mixed groutto achieve i n i t i a l se t .

ax. Unit Weight. The weight of freshly mixed grout per uni t volume,often expressed as pounds per cubic foot .

ay. Viscosi ty. Fric t ion within a l iquid due to mutual adherence of i t spar t i c l e s ; i . e . the thickness of a mixture.

az. Void Ratio. The r a t io of the volume of void space to the volume ofsol id par t i c l e s in a given s o i l mass.

ba. Washing. The physical act of cleaning a hole by ci rcula t ing e i the rwater, water and a i r acid washes, or water and dissolved chemical substances,through d r i l l rods or tremie pipe in an open hole.

bb. Water/Cement Ratio Cement Only). The r a t io of the amount of waterto the amount of cement in a grout mixture, expressed by weight or volume.

1-5

8/13/2019 EM_1110-2-3506

11/159

M 1110-2-350620 Jan 84

be. Water/Cement Ratio Total Cementitious Mater ia l s ) . The ra t io of theamount of water to the amount of t o t a l cementi t ious mater ia l s in a grout mixture , expressed by weight or volume.

bd. Water Table. The upper surface of a sa tura t ion zone, except wheretha t surface i s formed by an impermeable body.

be. Working Pressure. The pressure adjudged bes t for any par t i cu la r s e tof condi t ions encountered during grout ing. Factors inf luencing the determinat ion are s ize of voids to be f i l l e d depth o f zone to be grouted, l i tho logy ofarea to be grouted, grout viscos i ty, and res i s tance of the formation to f racture or u p l i f t .

bf . Zone A predetermined subdivis ion o f the overa l l depth of groutt reatment . - - -A-single zone m y make up the f u l l depth of t reatment , or thedepth of t reatment m y be divided in to several zones.

1-6

8/13/2019 EM_1110-2-3506

12/159

CMPnR2PURPOSES ND LIMIT TIONS OF GROUTING

EM 1110 2 350620 Jan 84

2-1. Purposes. Pressure grouting involves the in jec t ion under pressure of al iqu id or suspension in to the voids of a so i l or rock mass or in to voids between these materials and an exis t ing s t ruc ture . The injected grout musteventually form e i the r a gel or a sol id within the t rea ted voids, or thegrouting process must resul t in the deposition of suspended sol ids in thesevoids. The primary purposes of pressure grouting a so i l or rock mass are toimprove the strength and durabi l i ty of the mass and/or to reduce the perme-ab i l i ty of the mass. This manual provides guidance in the.use of pressuregrouting as a means to improve exist ing or ant ic ipa ted subsurface conditions.Information on procedures, mater ia l s , and equipment for use in planning andexecuting a grouting projec t i s included, and types of problems t ha t might besolved by pressure grouting are discussed. Methods of pressure grouting t ha thave proven to be effec t ive are described, and various types of grouts and

t he i r propert ies are l i s t ed .a. Permeability Reduction. Grouting applicat ions re la t ing to perme-

ab i l i ty reduction include: 1) in associat ion with other measures, reductionof hydrostat ic forces act ing on the base of water retent ion s t ruc tures and ontunnel l in ings ; 2) reduction of reservoir water loss; 3) in associat ion withother measures, inhib i t ion of in terna l erosion of foundation and embankmentmaterials ; and 4) f ac i l i t a t ion of excavation by s tabi l iza t ion, consolidat ion,and/or water control . For those applicat ions involving s t ruc tura l safe ty

i . e . hydrostat ic force reduction and erosion inhib i t ion) grout ing i s not tobe considered as the sole defense. Multiple defenses, such as grout ing in assoc ia t ion with drains and/or f i l t e r s , are to be used.

b. Improvement of Mechanical Propert ies . Grouting applicat ions re la t ingto mechanical property improvement include: 1) enhancement of bearing capaci t y, and 2) consolidat ion of overburden or highly fractured rocks to f a c i l i -t a t e surface or underground excavations.

c. Void Fi l l ing . Grouting may be necessary to f i l l both surface and subsurface voids.

d. Stabi l iza t ion and Lif t ing . Grouting i s used for the s t ab i l i za t ion offoundations and for l i f t i n g and s tabi l iza t ion of footings, s labs , andpavements.

2-2. Limitat ions. There are two general types of l imi ta t ions t ha t apply togrouting: 1) l imi ta t ions inherent in the physical nature of the grouting ma-t e r i a l s and in the physical and chemical proper t ies of the materials tha t thegrout wi l l contact , and 2) l imi ta t ions on grout ing operations and methods.Speci f ica l ly, grout ing l imi ta t ions are del ineated in the following paragraphs.

2 1

8/13/2019 EM_1110-2-3506

13/159

8/13/2019 EM_1110-2-3506

14/159

C ~ P r n R

EM 1110 2 350620 Jap 84

GEOLOGIC CONSIDER TIONS FOR INVESTIG TION ND DESIGN

3-1. Rock Types. The differ ing proper t ies of various rock types by nature oft he i r or ig in , l i thology, and s t ruc ture wil l influence the grouting conditionsa t a par t icular s i t e . A thorough knowledge of the rock types present a t thes i t e and t he i r geologic his tory, i s therefore essent ia l for the design andtreatment of the foundation. The explorat ion and grouting programs must beadapted to the s i t e geologic conditions. Different rocks with the same gene ra l fracture permeabil i ty and void charac ter is t ics can be loosely groupedtogether. Examples of some of the more common rock types are l i s t ed , togetherwith those general charac ter is t ics tha t could influence required foundationtreatment.

a. Crystal l ine. Crystal l ine rock i s an inexact but convenient term t ha tident i f ies igneous and metamorphic as opposed to sedimentary rocks.

(1) Intrusive igneous rocks include granites, syenites, d io r i t e s , andgabbros. Some features commonly found in these rocks are sheet jo in t ing ,shear zones, dikes, and s i l l s .

(2) Join t ing in three di rec t ions i s charac ter is t ic of in t rus ives . Onese t i s usually near-horizontal (sheet or u p l i f t jo in t ing) , and the other twoare near-ver t ica l and general ly normal to each other. The spacing of sheetj o in t s i s frequently close near the surface but increases with depth.

(3) Grout take normally occurs in the j o in t s and the f rac tures , and thevolume i s dependent on the size and continuity of the openings along the f ractures . Certain metamorphic rocks such as gneisses would react in a manners imi lar to tha t of the grani tes . Grout takes in schis ts and s la tes are dependent on the ~ e s e n c eand charac ter is t ics of associated jo in t ing or f inefracturing. Most quar tz i tes are highly fractured and would readily acceptgrout. Marble i s a crys ta l l ine rock but should also be considered in thecategory of kars t ic formations since so lu t ion cavi t ies should be anticipated.

b. Volcanics. Volcanics generally include the extrusive igneous rocks.Fe l s i t e s , a group of very dense, f ine-grained rocks, are extrusive and nearsurface equivalents of granites, syenites, and other related c rys t a l l i ne rocks.In addit ion to grani te- l ike jo in t ing they may also exhibit columnar s t ruc ture .Basal ts are a group of very dense, dark, igneous rock. The jo in t ing may bepla ty or columnar. Basal ts in many flows commonly exhibit columns with threeto s ix sides. Pumice and scoria are often associated with basa l t s . Pyroc las t i c s , such as agglomerates and t u ff s , are materials formed by explosivevolcanic ac t iv i ty and consist of fragments to rn loose by such explosions, ordeposi ts of wind-borne ash. Large-scale engineering operations in pyroclas t icrocks are general ly d i f f i c u l t . Volcanics require extensive examination beforeengineering charac ter is t ics can be determined and wil l usually require specialt reatment . The presence of columnar jo in t ing in lava flows tends to lower the

3 1

8/13/2019 EM_1110-2-3506

15/159

M 1110-2-350620 an 84

s t rength of the mass as a whole, and extensive grouting can be expected. Permeabil i t ies m y be grea t in lava flows due to the extensive j o in t ing whichnormally i s present and due to the presence of piped vesicles and gas cavi t ies .

These fea tures m y t ransmit copious flows of water. In some cases, however,the j o in t s are t i gh t and/or f i l l ed and the rock mass m y have a very low permeabil i ty. Each case must be evaluated individually to determine the need forand effect iveness of grout ing.

c. Soluble Rocks. Limestone, dolomite, gypsum anhydri te , and ha l i t eare included in t h i s group. The pr inc ipa l defec t in t h i s rock group i s solub i l i t y in varying degrees t ha t can ul t imate ly cause high mass permeabil i ty,slump, collapse, and s i n k ~/ resu l t ing in kars t topography.

1) Limestones and dolomites are the most widespread of the soluble sediments. These rocks m y be vuggy and m y disp lay a wide range of permeabil i tyas a uni t . Limestone and dolomite are general ly jo in ted and usually exhib i t

two or three d i s t inc t se t s of jo in t ing . Solut ioning i s frequently well developed along bedding planes and j o in t s , and contacts with other rock types.Join ts and cav i t i e s m y be e i the r f i l l e d or open and the s i ze m y vary grea t ly.Dependent upon the exten t of j o in t ing and cav i t i e s , extensive t reatment andgrouting can be ant ic ipa ted .

2) Anhydrite i s pure calcium su l f a t e whereas gypsum is the hydratedform. Both are so f t and fa i r ly soluble in water. Both types m y be jo in tedand have a varying number and s ize of so lu t ion cavi t ies . The cav i t i e s of tenare f i l l e d with clay or o ther reworked material . Grout takes depend on thepresence and cha rac t e r i s t i c s of the j o in t s and cavi t ies .

3) Hali te rock s a l t i s so f t and soluble in water. The extremelysoluble ha l i t e i s not found in outcrop but m y be found a t depth. The pr inc ipal engineering s igni f icance of ha l i t e i s the e ffec t i t s presence or proximitym y have on the proposed pro jec t , such as so lu t ion ing and subsidence, in addit ion to effec ts on groundwater.

4) Grouting in solut ioned l imestone and o l ~ i t eof ten meets with amixed degree of success . Grouting wil l f r q u n t ~ ydramatical ly reduce i n i t i a lseepage. However the seepage of ten has a tendency to increase with timea f t e r grouting i s completed. The increased seepage i s a t t r ibu ted to the eros ion of v o i d - f i l l i n g mater ia l s t ha t were not adequately removed before grouting. The eros ion or p ip ing of t h i s unconsol idated material creates seepagewindows in the grout cur ta in t ha t become progress ive ly la rger and more prol i f i c with t ime.

d. Clas t i c Sedimentary Rocks. Conglomerates, sandstones, s i l t s tones ,and sha les a re the pr inc ipa l types of c las t i c sedimentary rocks. The physicalproper t ies of sandstone, s i l t s tone , and conglomerate depend on the degree andtype of cementation. These coarser c las t i c s m y be t i gh t and impermeable, orm y be su ff i c i en t ly porous and permeable to need t reatment . Jo in t ing would be

3-2

8/13/2019 EM_1110-2-3506

16/159

M 1110-2-350620 an 84

the main concern in impermeable clas t ics as to need for treatment. The f inerc las t i c s , such as claystones and shales, are made up of clay minerals , variousoxides, s i l i c a f ine par t ic les of ordinary minerals , and some amount of col

lo ida l and organic materials . These clas t ics may contain a great amount ofwater. wo shale types are cementation shale and compaction shale. Compac-t ion shales usually contain no jo in ts capable of being grouted. Cementedshales are more res is tant to change and have engineering propert ies superiorto those of the compaction type. Cemented to s l igh t ly metamorphosed shalesare suff ic ient ly b r i t t l e to react to s t ructura l changes and develop jo in tss imi lar to those in sandstone.

e. Unconsolidated Materials. Unconsolidated materials include residualoverburden derived from the weathering of the parent rock. Residual soi ls arein s i t u as opposed to transported sediments. The propert ies of the materialsr e f l ec t to a cer ta in extent the propert ies of the or ig inal material . Finerderivat ions of the parent rock, such as clays and s i l t s are generally impervi

ous and would not require grouting. However in cer ta in instances where soluble rocks underlie the overburden, voids or very sof t and loose materialcaused from the col lapse of the overburden into the solution channels may require t reatment . Transported sediments may include outwash deposits and a lluvia l deposits generally found in stream val leys , te r race deposits , and mostglac ia l deposi ts . I f the projec t design does not require removal of these deposi ts , grouting or other treatment may be required to reduce or control permeabil i ty and improve s tab i l i ty. Soil samples should be invest igated by laboratory t ~ t for permeability, gradation, and densi ty.

3-2. Structura l Geology.

a. Structure. The term rock s t ruc ture refers to the spat ia l re la t ionships of rocks and thei r discont inui t ies , and affec ts engineering projec ts inmany ways. Folds and faul t s inf luence the se lec t ion of dam s i t es , and evensuch seemingly small matters as the spacing of j o in t s may have an importantbearing on the dis t r ibut ion of u p l i f t pressures.

b. Folds. A common type of deformation i s folding. The folded rocksoften show-cofisiderable fracturing along the axis of the fold. The sever i tyof engineering problems i s dependent upon the complexity of the fold with rel a t ion to the type and geometry of the proposed s t ruc tures and would includeexcavation, s t a b i l i t y, and leakage problems.

c. Faul ts . Faults are fractures along which masses of rock have beenmoved in a direc t ion para l le l to the faul t surface. The movement may varyfrom a few centimeters or less to many kilometers.

(1) Faults very rare ly show clean and uncomplicated break. The rockswi l l normally exhibit folding, f rac tur ing , crushing, and grinding. Sometimesthe walls exhibi t polished and smoothly s t r i a t ed surfaces called sl ickensides.The rocks on the opposite sides of the faul t surface may occasionally be

3-3

8/13/2019 EM_1110-2-3506

17/159

M 1110-2-35062 Jan 84

broken in to angular fragments re fe r red to as f au l t brecc ia . In addi t ion tothese mechanical e ffec t s , faul t s may resu l t in channels for ci rcula t ing wateror may be impermeable and form groundwater ba r r i e r s .

2) Recogni t ion of f au l t s i s of grea t importance because f au l t s represen t zones of weakness in the crus t o f the ea r th , and the presence of thesezones would a ff ec t the engineer ing proper t ies of a s i t e , including seismologica l cons idera t ions , excavat ion, tunnel support , dam s t a b i l i t y, and leakageproblems.

d. Jo in t s . Jo in ts are almost universa l ly presen t and are of considerable engineer ing importance for t ha t reason. Jo in ts offe r channels for groundwater ci rcula t ion , and jo in t s below the groundwater table may grea t ly increasewater problems. Jo in ts may a lso exer t an important inf luence on weatheringand excavation cha rac t e r i s t i c s .

e. Grouting Considerat ions. Since many rock types have a low primarypermeabil i ty but a r e l a t i ve ly high f rac ture and j o i n t permeabil i ty, the importance of grout ing the s t ruc tu ra l defec ts i s apparent. The type of s t ruct u ra l fea ture e .g . f a u l t , fo ld , j o i n t wi l l d i c t a t e to a large exten t thetype and exten t of excavat ion t reatment and the grouting methods. The spacingand nature of the f rac tures e .g . open, weathered, solut ioned) inf luence thetype o f grout t reatment se lec ted , such as consol idat ion grout ing and cur ta ingrout ing. The se lec t ion o f a s ing le - l i ne or mult ip le - l ine cur ta in and thegrout hole spacing are a lso affec ted . The or i en t a t i on dip and s t r ike ) o fthese fea tures in r e l a t i on to a s t ruc tu re inf luences the planned angle anddi rec t ion of the grout holes and the dra in holes . The depth o f the f rac turesa ff ec t s the depth of a grout cur ta in . The grout holes should i n t e r sec t a l lthe fea tures , and each inc l ined or v e r t i c a l fea ture should i dea l l y be i n t e r -

sected by severa l holes a t d i ff e r en t depths. Faul t s may be gouge f i l l e d andimpermeable, thereby forming a b a r r i e r , or may be open and carry groundwater.Jo in ts may be f i l l e d o r open, may have weathered o r nonweathered faces, andmay i n t e r sec t and be connected over a wide area. The condit ion of the j o i n t swould a ffec t the d r i l l i n g , the cleaning, the pressure t e s t ing , and the grouting of the hole. Since s t ruc tu ra l fea tures inf luence the grouting program soprofoundly, the s i t e explora t ion should be su ff i c i en t ly thorough to base thedesign on ac tua l s i t e condit ions.

3-3. Geohydrology. Almost a l l engineer ing projec ts are a ff ec t ed by subsurface water. The importance o f subsurface water i s espec ia l ly obvious in respec t to water re ten t ion s t ruc tu re s . A thorough understanding of the regionaland s i t e spec i f i c groundwater condit ions i s necessary to safe ly design, cons t r u c t , and operate these projec ts . A b r i e f discussion of a few generalpr inc ip les fol lows. Applicat ion o f the pr inc ip les to spec i f i c problems suchas foundat ion t reatment and grouting can then be determined.

a . Poros i ty and Permeabil i ty. Almost a l l rocks contain pore spaces tosome extent . o be permeable, however, pore spaces in rock must be

3-4

8/13/2019 EM_1110-2-3506

18/159

M 1110 2 3506~ ~

interconnected and suff ic ient ly large to allow the passage of water. Mostsandstones are both porous and permeable. Shale, on the other hand, has ahigh porosi ty but the pores are l imited to capi l la ry sizes and water passage

through the shale i s extremely slow. Although i n t ac t shale i s porous but im-permeable, jo in ts and other fractures permit the passage of water even thoughthe water cannot readily pass through the i n t e r io r of the joint-bounded rocks.Even in regions where the bedrock i s granite or a s imi lar ly massive and impermeable rock, water occurs in fractures a t l eas t in l imited quant i t ies and tosome depth. Understanding the nature of the j o in t system i s of crucia l im-portance in areas such as these.

b. Groundwater.

1) Groundwater i s the water in the zone of sa tura t ion . The upper l imi tof th is zone i s referred to as the water tab le . The depth to the water tab lemay vary considerably depending on s i t e conditions. The groundwater may be

found ei ther in continuous bodies or in several separate s t ra ta , and the thickness may vary considerably. Local saturated zones tha t may occur above themain water tab le are termed perched water.

2) Local geology, permeability of the formations, including solut ioningand f rac tur ing , and recharge and movement within the zone are factors tha t affec t aquifer character is t ics . ny mass of permeable rock material from whicha s igni f icant amount of water can be recovered i s called an aquifer. Aquifersmay be unconfined or confined. n unconfined aquifer occurs when the upperl imi t of the aquifer coincides with the water tab le , since the surface of thewater i s a t atmospheric pressure. The hydraulic pressure a t any leve l underth is system i s the same as the depth from the water tab le to the subject depthand may be expressed as hydraulic head in fee t of water. Water under ar tes iancondit ions i s under hydrostat ic pressure and therefore r i ses in a well. Whenthe pressure i s suff ic ient to bring the water above the ground surface, aflowing ar tes ian well occurs. Water tha t r i ses only to an intermediate leve li s a nonflowing ar tes ian well.

3) Artesian water also occurs in a similar fashion in jointed bedrock.Certain se ts of jo in ts may be more openly developed, and a large amount ofwater may gather in the j o in t s under ar tes ian conditions. A r i l l may passthrough a few hundred fee t of impermeable rock in which the jo in ts are few andt ight ly closed. When the permeable, jo in ted zone i s reached, the hydrostat icpressure a t tha t depth causes the water to r i se . The number of j o in t s , aswell as the degree of openness, normally decreases with depth, and the chance.of penetrat ing a water-bearing zone i s generally greates t in the upper port ionof the bedrock.

c. Springs. ny natura l surface emergence of water from a subterraneancourse i s a spring. Many small springs represent water from ra in or snow fromhigher ground t ha t moves under gravi ta t ional force to a place of emergence.The course and flow ra te of a spring depend on the permeabil i ty and s t ruc ture

3-5

8/13/2019 EM_1110-2-3506

19/159

M 1110-2-350620 Jan 84

of the mater ia l through which the water moves Some springs flow upward witha measurable force, ind ica t ing t ha t they are under pressure. Springs are mostcommon in sandstones, cavernous carbonate rocks, ves icu lar lava flows, and

highly jo in ted or f rac tured rocks of any kind. Some of the la rges t springsdevelop along the borders o f karst regions.

d. Water Quali ty. The qual i ty of the groundwater i s pr imar i ly due tothe mineralogical charac te r o f the reservoi r rocks and t he i r degree of so lub i l i t y in water. The groundwater in l imestone areas usual ly contains a l a rgeproport ion of dissolved carbonates . Rock s l t ha l i t e ) furnishes a readysource of chlor ides , while gypsums and anhydri tes supply quant i t ies of sulfa tes . Water containing humic and other acids, dissolved su l f a t e s , chlor ides ,and s imi la r chemicals may ac t cor ros ive ly on s tee l and i ron and may be inju r ious to grout and concrete. Ferrous i ron in water may oxidize in to an uns ight ly l imoni t ic s t a in in ce r t a in cases. Iron may a lso lead to developmentof growths of i ron bacter ia . The source of the ferrous i ron i s genera l ly

rocks t ha t contain pyr i te or marcasite i ron su l f ides ) . These minerals arecommon in many sha les , espec ia l ly carbonaceous shales. Water from suchsources may a lso contain hydrogen sul f ide . In areas where coal mining has occurred, both ground and surface water may be highly ac id ic .

e. Grouting Considerations.

1) Since groundwater condit ions have an important e ffec t on design andcons t ruc t ion , the regional and local condit ions must be studied during the inves t iga t ion stages so t ha t potent ia l problems may be evaluated. The grout ingprogram should be designed for the exis t ing groundwater condit ions as well asfor pos tcons t ruc t ion condit ions. Differen t methods and procedures may be em-ployed, depending on the formation permeabil i ty, the depth to water t ab l e , and

the type of aqui fe r p resen t confined and unconfined). These condit ionsa ffec t the type o f grout , the grout ing procedure, the depth and exten t oftreatment , the spacing of ho les , the need for a mul t ip le - or s ing le - l i ne groutcur ta in , and the pressures t ha t should be used.

2) Aquifer condit ions a lso have a d i r ec t bearing on the need for andtype of drainage required. The chemistry of the groundwater should be cons idered with respec t to the mater ia l s to be used in the proposed s t ruc ture andto the grout to be used. Samples should be t e s t ed for p and the chemistryanalyzed. Springs in the cons t ruc t ion area may requi re spec ia l t reatment , including special grout ing methods.

3-4. Inves t iga t ion Methods.

a . Background.

1) Invest igat ions must be or ien ted toward ident i fy ing both the normaland the abnormal condit ions and the discont inui t ies of even the smal les tdegree, because these condit ions may cont ro l the design of the s t ruc tu re .

3-6

8/13/2019 EM_1110-2-3506

20/159

M 1110-2-3506?0 Jan 84

Special dr i l l i ng procedures and equipment with deta i led at ten t ion to the discontinuties and anomalies may be required. Besides the grouting design, theinvest igat ions are also used to determine the type and exten t of excavation,

groundwater condit ions, and foundation preparat ion and treatment required.2) The type and scope of the dr i l l i ng program are determined by the

type of the proposed projec t and by the geology. The staged invest igat ionsmay emphasize cer ta in geologic features, such as strat igraphy and s t ruc tu re ,groundwater inves t iga t ions , or foundation analysis . Therefore, a var ie ty ofinves t iga t ive methods may be required. These may include seismic and e lect r i c a l r e s i s t iv i ty surveys, core holes of a l l s i ze s , noncored holes, calyxholes for in s i tu foundation inspect ion, downhole logging techniques, swabt e s t s pump t e s t s pressure t e s t s and borehole photography. Each holedr i l l ed should be designed to give the maximum information poss ib le t ha t i sper t inent to the s i tua t ion .

b. Si te Conditions. Since grouting and drainage requirements and procedures are pr imar i ly based on geological condit ions a t a par t i cu la r s i t e andproposed s t ruc tu re , the explorat ion program must be comprehensive and accurate .I f invest igat ions confirm the presence of cer ta in adverse geological condit ions , treatment by excavation, grouting, or relocat ion of the s i t e may needto be considered. The adverse condit ions may include such things as the presence of soluble rocks, evidence of solut ion ac t iv i ty, prominent open jo in t s ,broken or in tens ive ly jo in ted rock, sheet j o in t ing , open bedding planes , f au l ting, or unusual groundwater condit ions. Besides dr i l l i ng a t the s i t e as described in para c . and where no outcrop ex i s t a t the s i t e observations ofthe same formations should be made a t nearby outcrops to get a be t t e r feel forj o in t and f rac ture spacing, continuity, and openings.

c. Dri l l ing . Specif ic information on subsurface conditions i s needed toplan the grouting program. o determine the scope and to est imate the costsof dr i l l i ng and grouting operations in rock, information should be availableon: overa l l geologic s t ruc ture and strat igraphy; or ienta t ion , a t t i t ude , andspacing of j o in t s ; jo in t openings including type of any f i l l e r ; boundaries ofrock types; locat ion of f au l t s ; loca t ion of broken zones, depth to sound rock,and posi t ion of water tab le . Suff ic ient dr i l l i ng should be performed todel ineate the above features. Tools such as borehole and te lev is ion camerasand geophysical logging instruments should be used where needed to define subsurface condit ions. Extensive use should be made of angle holes to give themaximum information poss ib le concerning high angle jo in t ing and faul t ing , part i cu la r ly on the abutments where sheet or r e l i e f j o in t s of ten occur. Eachhole should be pressure tes ted and/or pumped to determine not only water takebut to i so l a t e the water-bearing or open zones in the hole. Therefore thehole should e i the r be tes ted as i t i s dr i l l ed or tes ted by the use of as t raddle packer a f t e r d r i l l i ng i s completed. I f a r t e s i an condit ions are encountered, these zones should be i so la ted and tes ted .

3 7

8/13/2019 EM_1110-2-3506

21/159

M 1110 2 350620 Jan 84

3-5. Test Grouting.

a. General. Field grouting t e s t s pr io r to deta i led design are very im-

por tan t . They provide the most accurate information for designing the completegrout program and for est imating the quant i t ies to be required. The groutt e s t can also be very valuabie in evaluat ing the effect iveness t ha t m y be expected from the complete cur ta in . The grout t e s t can also provide informationas to which dr i l l i ng method i s most adaptable to the rock formation to begrouted.

(1) A t e s t performed in each different geologic environment t ha t the cons t ruc t ion grouting wi l l encounter i s usua l ly advisable i f the differences ares igni f icant .

(2) The grout t e s t m y range froao a very simple t e s t of several d i ffe ren t grout mixtures pumped into a few holes to determine the amount of each

mix t ha t can be in jec ted , to a very comprehensive t e s t t ha t uses observat ionwells and pump t e s t s before and a f t e r to evaluate the effect iveness of thegrouting. The type of t e s t selected should be based upon information needed,s ize of projec t , and complexity of geologic condit ions. The grout t e s t shouldbe supervised in the f i e ld by the ge ologist responsible for designing thef ina l grouting program. Test ing should not include rock which wil l be excavated during the projec t construct ion.

b. Single Line Test Curtain.

(1) The simplest grout ing t e s t i s to d r i l l and grout a l i ne of holesalong the proposed grout l ine . Very careful records should be kept of eachoperat ion involved in the t e s t . I t i s normally advisable to begin the grouting with a th in mixture, such as s ix par ts water to one par t cement, thengradually thicken the mixture i f the hole continues to take grout . Care mustbe taken not to i n j ec t the hole with a mixture t ha t i s too th ick and wil l stopthe hole from taking grout prematurely. I f th is appears to be happening, im-mediately th in the mixture being pumped.

(2) Grouting of one hole i s not an adequate grout t e s t . Geologic condit ions are normally f a r too var iab le for one hole to be representa t ive . Thenumber of holes used for a grouting t e s t must be based on the des igner s judgment and knowledge of the geologic condit ions, but normally would includes p l i t spaced holes, t ha t i s holes spaced equidistant between previous lygrouted holes.

(3) The main benef i t from a s ingle l i ne grout t e s t i s to obtain an indicat ion of the amount of grout the formation wil l take for est imating purposesand primary and s p l i t spacing distances. I t a lso provides design informationon dr i l l ing and grouting procedures to use.

3-8

8/13/2019 EM_1110-2-3506

22/159

c. Circle Grouting.

M 1110 2 3506~ ~

(1) A more comprehensive grout t e s t i s performed by grouting an area

around at e s t

well . Thist e s t

wil l providea l l

of the information describedin b above and wil l also allow an evaluation of grouting effect iveness by running pump tes t s before and a f t e r in the observati ft_well.

(2) A t e s t should be made with a radius of about 5 feet depending onrock propert ies. The grout holes dr i l l ed around the circumference of thec i rc l e should be spaced as planned for the f ina l grout curtain. The holesshould be dr i l led and grouted according to the spl i t - spac ing proceduresnormally followed in grouting.

(3) At leas t two l ines of piezometers should be ins ta l led along l inesradiat ing from the t e s t well , which should be dr i l l ed a t the center of thec i rc le . I t i s normally of most benefi t for a dam project to align the p i

ezometer l ines essent ia l ly para l l e l to the anticipated l ines of flow from theimpounded lake. Good locat ions for piezometers are one inside the c i rc le , onein the grout cur ta in , and two outside the c i rc l e on each l ine .

(4) Pump t e s t s should be made before and a f t e r the grout i s placed. Thedifferences in the permeabil i ty between the two t e s t s are a ref lec t ion of theeffect iveness of the grouting. The t e s t well and the piezometers wi l l some-times become grouted up during the grouting operation, and r e ins t a l l a t ion wil lbe necessary a f t e r the grout i s placed and before the f ina l pump t e s t i sperformed.

d. Multiple Line Grouting. A sa t i s fac tory grout t e s t may be performedin some cases by dr i l l ing two or more l ines of grout holes along the proposedgrout curtain and a t e s t well adjacent to the grout cur ta in . The t e s t wellshould be pump tested before and a f t e r the grouting operat ion. A l ine of p iezometers should be ins ta l led across the curtain to measure drawdown beforeand af te r grouting. The well or the piezometers may become clogged during theplacement of grout , in which case new ones should be ins ta l led . Most of theinformation available from c i rc l e grouting t e s t s i s also available from t h i st e s t Multiple l ine grouting has the advantage of requir ing fewer grout holesand less space to perform the t e s t than required for c i rc l e grouting.

e Observation Wells and Piezometers. Test wells and piezometers areuseful in evaluat ing the effect iveness of the grout curtain.

(1) Well depth should be somewhat less than tha t of the grout holes. I fthe well i s cored, the core should be carefu l ly logged to note the loca t ion offractured zones. The well should be pressure tes ted with straddle packers tolocate permeable zones in the hole.

(2) Piezometers or observation wells should be ins ta l led so tha t thecone of depression can be established and the permeabil i t ies of the rock

3-9

8/13/2019 EM_1110-2-3506

23/159

M 1110-2-350620 an 84

formation can be computed for the pumping t e s t s before and af te r grout placement. The piezometers can normally be ins ta l led in smaller diameter holessuch as NW (75.7 mill imeters in diameter) . Their depths, l i ke those of the

t e s t wells , should be somewhat less than the depth of the grout holes, s incethe purpose of the piezometers i ~ to provide an indicat ion of the e ffec t ofthe grout curtain on the permeabil i ty of the rock in which i t i s ins ta l led .The piezometers should be ins ta l led so tha t they are open to most of the column of rock in the hole. I t i s frequently acceptable to i n s t a l l piezometersby se t t i ng and grouting the casing in to firm rock, then dr i l l ing to theplanned depth and leaving the rock por t ion of the hole in open communication.The casing i s l e f t in place to serve as the piezometer pipe. Obtaining a sea lbetween the casing and the rock i s very important in t h i s type of i n s t a l l a t ion .This type of piezometer i s actua l ly a small-diameter observat ion well.

(3) A more sens i t ive piezometer i n s t a l l a t ion consists of a smalldiameter porous tube, or wellpoint , approximately 2-1/2 fee t long connected to

a small-diameter r i s e r pipe. The porous tube, or wellpoint , i s se t near thebottom of the dr i l led hole, and sand i s placed in the hole below, around, andabove the tube. A sea l of bentonite pe l l e t s i s ins ta l led above the poroustube or wellpoint . This type of piezometer has two advantages over the openhole i n s t a l l a t ion described in (2) above: (a) I t i s considerably less l ike lyto become grouted up during grouting operat ions because the grout wil l nott r ave l f a r through the sand pack, and (b) i t r e f l ec t s changes more quickly inthe water tab le in the surrounding rock because much less storage area i savai lab le for water in the hole.

f . Exploratory Holes. Exploratory holes dr i l l ed into the grout cur ta inare frequently advisable to evaluate grout in t rus ion in to the f rac tures andf i ssures in the rock. I t may be necessary to d r i l l large-diameter core tofu l ly recover grout in the f rac tures for evaluat ion. The chemical phenolphthalein 20H14

4 may be used to ident i fy t races of grout in rock core.

The exploratory holes should be pressure tes ted .

g. Evaluat ion of Results . Where t e s t grouting i s above the exis t ings t a t i c water l eve l , drawdown pump t e s t s cannot be used to evaluate r e su l t s .Considerat ion of the grout mixtures and pressures used, the reduct ion of takewith s p l i t spacing, pump-in t e s t r e su l t s before.and a f t e r grouting, and coreholes as discussed in paragraph f are the pr incipal methods for evaluat ion.Geophysical methods have also been used, but are not as re l iable . In evalua ting reduct ion of take with s p l i t spacing, i t i s helpful to reduce the data toa uni t take such as take expressed as cubic fee t of grout per foot of d r i l l

hole.

h. Determination of Dri l l i ng Procedures. ne important piece of designinformation t ha t should be obtained from a t e s t grouting program i s an evaluat ion of the bes t dr i l l ing method to be used to d r i l l the grout holes a t t ha tpa r t i cu la r s i t e Rotary and percussion dr i l l ing techniques should be

3-10

8/13/2019 EM_1110-2-3506

24/159

M 1110-2-3506~ ~

evaluated. Various grout hole diameters should a lso be t r ied and evaluated.f these parameters are estaolished during the t e s t grouting program they can

be specif ied for the complete program and should el iminate the poss ib i l i t y ofexpensive cont rac t modif icat ions.

3 11

8/13/2019 EM_1110-2-3506

25/159

CH PTER 4PL NNING ND PROCEDURES

EM 1110 2 3506~ ~

4-1. Considerations. The need for grouting should be determined ear ly in the .planning stage of a projec t and should be governed by the requirements for thepar t icular structure and geologic se t t ing . Grouting to reduce seepage tha tmight have an adverse effec t on performance of a s t ruc ture i s the most commondesign purpose for grouting. Grouting also provides thorough explorat ion ofpossible adverse condit ions. f foundation seepage i s not detrimental to thes t ruc ture a deep grout curtain may not be necessary. Economics may dic ta tegrouting to reduce water losses in cases where water i s valuable such as inan upper reservoir of a pumped storage projec t .

a. Geologic Considerations. Plans for a grouting program should bebased on the knowledge obtained during exploratory invest igat ions of the geologic conditions. The design of grouting programs should never be based on a

predetermined formula but should be selected to accomplish the design purposeof the grouting in the geologic se t t ing a t hand. Geologic considerations arerequired from the i n i t i a l planning stage through the completion and evaluat ionstages of the grouting program.

b. Program Objectives. The planning of grout ing operat ions and techniques i s not only influenced by the subsurface conditions encountered butalso by the purpose and object ives of the grouting program. Is the groutingintended to be a permanent t reatment or i s i t a temporary construct ion expedient? Is the t i gh tes t cutoff obtainable needed or i s something l e s s thant ha t acceptable? Should the maximum amount of grout possible be in jec ted in tothe rock regardless of spread or should an e ffo r t be made to r e s t r i c t thespread to reasonable l imi t s or should i t be r e s t r i c t ed to very narrow l imi t s?

The answers to these questions and the effec ts of the often overr iding factorsof time and cost form the bas is for planning dr i l l i ng and grouting operat ions.The treatment of a reservoir to permanently s tore a l iqu id pol lu tant i s an example of one extreme. Suff ic ien t time and money must be al located and everye ffo r t and decision designed to provide the t i gh tes t sea l poss ib le otherwisethe projec t cannot be successful . At the other extreme a grouting programmay be conceived to reduce but not necessari ly to stop seepage in to an excavation during construct ion as a measure to save on dewatering costs . Timewil l be a fac tor i f grouting delays other work. Cost i s a fac tor since thesaving on dewatering costs must be a cei l ing for grouting costs . Permanenceof t reatment i s not v i t a l in t h i s case and grout ing techniques are directedtoward construct ing the most effec t ive cutoff possible for a specif ied expenditu re of time and money. The object ives of most grout ing operat ions f a l l between the examples ci ted above. The object ives for a l l grouting should beclear ly defined so t ha t the designer geologis t project engineer and inspector wil l understand them and can then contr ibute to t he i r rea l iza t ion .

4-1

8/13/2019 EM_1110-2-3506

26/159

M 1110-2-350620 Jan 84

4-2. Planning Considerations.

a. After the need for and purpose of grouting has been determined, the

planning of a grouting program can begin. Planning should consist of:1) Making a study of exploratory invest igat ions and using the informa

t ion to determine the extent , method and parameters for the safe and e f f i c i -ent in jec t ion of grout into the foundation and t ha t wi l l provide the optimalhole or ienta t ions , depth, and spacing.

2) Determining a t ~ h tprojec t construct ion stage the grouting shouldbe done.

3) Preparing sui tab le plans and spec i f ica t ions t ha t wil l represent s i t econdit ions and work to be performed.

4) Estimating dr i l l i ng quant i t ies and amount of grout materialsrequired.

b. Unforeseen geological condit ions may necess i ta tegrout ing program a f t e r grouting operat ions are under way.b i l i t y should be provided as an in tegra l par t of planningserved through the completion of the grout ing.

modif icat ion of theTherefore, f l ex i

and should be pre-

c. Grouting i s usua l ly on the c r i t i c a l path of cons t ruc t ion , and, withpar t i cu la r weather r e s t r a in t s , there i s a tendency to modify or cur t a i l grouting as a cons t ruc t ion expedient . Once the determination i s made t ha t grout ingi s a required par t of design, i t cannot become secondary to any time orscheduling r e s t r i c t ions .

4-3. Qual i ty Management. I t i s extremely d i f f i c u l t to determine the qual i tyof the end product resul t ing from a grout ing operat ion. s a consequence, thepor t ions of a cons t ruc t ion contract deal ing with grout ing almost invar iab lyspec i fy a very deta i led cons t ruc t ion procedure. The specif ied deta i led cons t ruc t ion procedure and the d i ff i cu l ty in determining the qual i ty of the pos tgrout ing end product combine to make the grout ing qual i ty management programextremely important.

a . Qual i ty of Personnel. Guidance for Corps personnel s t a ff ing on Civi lWorks Construction Projects i s contained in ER 415-2-100. Staff ing for grouting work sha l l be with qual i f ied personnel , preferably with key personnelhaving pr io r grout ing experience. The s t a f f shal l include an engineeringgeologis t or geotechnical engineer and one or more t echnic ians qual i f ied toperform the day-to-day supervision of grout ing a c t i v i t i e s The geologist orengineer sha l l be experienced in grout ing and foundation design. Depending onthe complexity of the pro jec t other technical spec ia l i s t s may be required.These spec ia l i s t s shal l e i the r be assigned d i rec t ly to the projec t or beavai lab le for prolonged and frequent temporary assignments from other

4-2

8/13/2019 EM_1110-2-3506

27/159

M 1110-2-3506~ ~

organizat ions. On large projec ts , assignments in the ear ly stages of groutingmay be arranged so t ha t inexperienced personnel can observe the ac t ion anddecisions made by an experienced s t a f f Thus, a competent team can be t rained

tha t wil l operate a t maximum eff ic iency a t al a t e r

time when the work is infu l l swing. Some grouting operat ions, however, may not involve a large organizat ion, and the grouting technician wil l not have anyone with experience inthe pecu l i a r i t i e s of t h i s work to whom he can turn quickly for advice andcounsel. Only experienced construct ion personnel should be given s ~ hassignments.

b. Grouting Records. Under most cont rac t requirements, the cont rac torwil l keep daily records of a l l items for measurement and payment. These i temsshould be reconciled on a daily basis and agreement reached between the cont r ac to r and Government on a l l measured quant i t ies . Disputes over paymentitems should be reconciled as soon as poss ib le between responsible representat ives of the cont rac tor and the Government. The cont rac t ing off i ce r w i l l keep

records of a l l grouting operat ions, including but not l imi ted to a log of thegrout holes , resul t s of washing and pressure t e s t ing operat ions, time of eachchange of grouting operat ion, pressure , ra te of pumping, amount of cement foreach change in water-cement r a t io , and other data as deemed necessary. Theserecords are a valuable too l for the evaluat ion of each step of the groutingprogram. To f a c i l i t a t e control of the grouting program and provide a graphicpic ture of the r e su l t s for review, an up-to-date visua l p lo t of the groutingoperat ions should be maintained. A further de ta i led discussion of groutingrecords and reports i s contained in Chapter 15.

4-4. Grout Hole Dri l l ing .

a . Location. The locat ion for the grout holes i s determined by the type

of s t ruc ture to be grouted, geologic condit ions, and purpose of the grout ing.

b. Hole Size. The diameter of grout hole selected wil l be based uponthe type and condit ion of the rock to be grouted and the depth and inc l ina t ionof the hole. The grout hole required should normally be specif ied as the minimum acceptable diameter. The cont rac tor may e lec t to d r i l l a l a rger diameterhole. Minimum hole sizes normally specif ied range from 38 to 7 mill imeters

1.5-3 inches) . Except where percussion dr i l l i ng i s used, the smaller diameterholes may be preferred because of t he i r lower cost .

c. Selec t ion of Minimum Hole Size. Hard rock with widely spaced, r e l at ive ly clean f rac tures may be success fu l ly grouted through W 38 mill imeters)holes. Larger diameter holes are required for successful dr i l l i ng and grouting in rock of poorer qual i ty. Conditions to be considered are rock format ions t ha t 1) tend to cave in , 2) contain fractures f i l l ed with unconsolidated mater ia l , or 3) contain open j o in t s and f rac tures which may be intrudedby d r i l l cut t ings . The la rger diameter holes wi l l allow the inser t ion of awash pipe or tremie pipe in the hole with su ff i c i en t space between the pipeand the wall of the hole for removal of cutt ings or grout and for washing or

4-3

8/13/2019 EM_1110-2-3506

28/159

M 1110-2-3506~ ~

backf i l l ing . Larger diameter holes may also be required to produce as t ra ighter hole. Drif t due to smaller diameter and more f lex ib le d r i l l rodsmay be excessive. Other factors affect ing minimum hole s ize include hole

depth, anticipated grout mixture, and method of grouting.d. Spacing. The spacing, as well as the pat tern , of grout boles should

be based on geologic conditions, the resul t s expected to be obtaned, and thepurpose for which the grouting i s being done. The spacing wi l l be influencedby the charac ter is t ics of the foundation and, in the case of curtain grouting,by the hydrostat ic head to which i t wil l be subjected. Primary hole spacingsshould be su ff i c i en t ly wide so tha t connections between grout holes do notnormally occur. In pract ice , primary hole spacing commonly varies from 1 to4 feet . Final spacing between 2-1/2 and 10 fee t i s common or cur ta in groutholes. Aside from primary hole spacing and the maximum allowable spacing,however grout hole spacing cannot be predetermined s a t i s f a c t ~ r i l yThe f ina lspacing should be determined during the grouting operations on the basis of

the resul t s being obtained from these operat ions. Holes in c ~ r t a i ngrouting,for example may s t i l l take considerable quant i t ies of grout a f t e r hole spacing has been reduced to an anticipated minimum in terval , and the spacingshould be reduced further un t i l the section or area i s considered to begrouted sa t i s fac to r i ly. Curtain grout boles on some projects have been spacedas close as 1 foot on center.

e. Depth. The depths to which grout boles are dr i l l ed should be governed by conditions in the foundation rock, and for cur ta in grouting, by thehydrostat ic head to which the foundation rock wil l be subjected Depths for agrout cur ta in should be suff ic ient to minimize seepage and ass is t in the reduct ion of u p l i f t and the need for extensive drainage f a c i l i t i e s Where condit ions permit , grout holes should bottom in sound, re la t ive ly impervious rock.

Depths should never be based simply on precedent.

f . Direct ion. Grout holes for cur ta in grouting of concrete dams are commonly incl ined in an upstream direc t ion , and dr i l l ing and grouting i s donefrom a gal le ry. Inc l in ing the holes allows them to in tersect ve r t i ca l orsteeply dipping fractures and j o in t s tha t would not be in tersec ted otherwise,and holes incl ined in an upstream direc t ion provide an adequate separat ion ofthe grout and drainage cur ta ins . The direc t ion in which to d r i l l any grouthole should be based on the nature of the imperfections to be grouted, thepurpose of the grouting, and the environment under which the grouting i s done.Grout holes should be dr i l l ed in such a direc t ion and angle as to i n t e r sec t asmany of the imperfections in the rock as possible for the prevail ing condit ions . Angle or horizontal grout holes should be incorporated in abutmentswhere needed.

g. TyPes of Dri l l ing . Dr i l l ing experience gained during foundation inves t iga t ions should be considered in the se lec t ion of the type or types ofdr i l l ing to be used in the grouting program. There are different types of

4-4

8/13/2019 EM_1110-2-3506

29/159

M 1110-2-350620 Jan 84

dr i l l i ng which may be selected for grout hole dr i l l i ng . Each has advantagesand disadvantages.

1) Rotary dr i l l i ng . Perhaps the most common type of dr i l l i ng used ingrouting is rotary dr i l l i ng . Clear water is normally used as the medium forremoval of d r i l l cutt ings. Diamond bi t s are usua l ly used to advance the hole.In some cases the b i t s may be coring b i t s and in other cases they may be plugb i t s . In sof t rock dr i l l ing , drag b i t s may be used. In those s i tua t ionswhere i t i s espec ia l ly important to prevent d r i l l cutt ings from intruding rockf rac tures , reverse ci rcula t ion rotary dr i l l i ng may be used. This technique i smore time consuming and expensive than conventional rotary dr i l l ing and shouldonly be specif ied in those cases where i t i s required for sa t i s f ac to ry groutin jec t ion . n advantage of the rotary dr i l l i ng method i s tha t i t permitsready i den t i f i ca t ion of in terva ls in the foundation where dr i l l i ng f lu id i sl o s t , thus allowing the dr i l l i ng to be stopped and the i n t e rva l grouted beforethe f rac ture or fractures become clogged. Another advantage i s t ha t the hole

can be washed clean a f t e r d r i l l i ng without removal of the d r i l l from the hole.Disadvantages of rotary dr i l l ing are t ha t i t may be more cos t ly than percussion dr i l l i ng , and d r i l l cutt ings tend to intrude into fractures by the pressure of the dr i l l i ng f lu id .

2) Percussion dr i l l i ng . A second type of dr i l l i ng i s percussion d r i l l -ing. There are several var ia t ions of t h i s technique. One method is to useblas t -hole type d r i l l s with a i r aud/or water as the medium for removingcut t ings . A second method i s to use a down-the-hole hammer with a i r as themedium of cutt ing removal. Both types of d r i l l s have been used successful lyfor grout hole dr i l l i ng . In cases where i t i s necessary to d r i l l through azone or stratum which contains clay or s i l t t ha t tends to ba l l up in the holeand block the passage of the a i r small quant i t ies of water may be in jec tedinto the a i r stream with a high pressure, low capaci ty pump This oftengrea t ly improves performance of the d r i l l through these in tervals . In somecases i t may also be useful to introduce a foaming agent with the water tof a c i l i t a t e removal of clay cutt ings. The advantages of t h i s type of dr i l l i ngare t ha t i t i s normally l e s s expensive than ro ta ry dr i l l ing , hole advance i sf a s t e r, and there i s l e s s tendency to intrude rock fractures to s ign i f i can tdepths with d r i l l cutt ings in those cases where a i r ra ther than water i s usedas the medium of cutt ing removal. A disadvantage i s the tendency to smear thewall of the hole with cutt ings in sof t rock types. After the hole i s com-pleted i t should be thoroughly washed to remove any smeared cut t ings . In somecases, f rac tures in so f t rock are f i l l e d with cutt ings which cannot be removedby washing. Another disadvantage i s tha t c i rcula t ion losses are usually notapparent where a i r alone i s used, thus el iminat ing one of the main c r i t e r i a onwhich a dec is ion i s made to stop and stage grout the hole a f t e r encountering afeature which needs grouting. Another disadvantage i s the poss ib i l i t y of subjec t ing the hole to the f u l l pressure of the compressed a i r should a blockageoccur above the b i t . These pressures may be capable of l i f t i n g or jacking thefoundation due to in t rus ion of a i r along low angle fractures in the rock.This concern i s magnified i f the grout holes are being dr i l l ed through a

4-5

8/13/2019 EM_1110-2-3506

30/159

M 1110-2-350620 Jan 84

completed embankment. Blockages in the hole wil l subject the embankment tothe fu l l a i r pressure and wil l probably f rac ture the embankment f i l l . The useof a i r dr i l l i ng in embankments and t he i r foundations has now been prohibi ted

by the Corps of Engineers ER 1110-2-1807).4-5. Types of Treatment.

a. General Considerations. The types of grout ing t reatment applicableto c iv i l construct ion f a l l into one of the following categories: 1) cur ta ingrouting, 2) area grouting also referred to as consol ida t ion , s t ab i l i za t ion ,or blanket grouting), 3) tunnel grouting, 4) cavity f i l l i n g 5) backf i l l ingboreholes, 6) contact grouting, and 7) special ized applicat ions. Treatmentby grouting i s an important design feature of many dam and s t ruc tu ra l foundat ions . Grouting has also been effec t ive many times as a remedial t reatment tocorrect foundation deficiencies or to repai r damage.

b. Curtain Grouting.

1) Curtain grouting i s performed to cut off seepage under dams or others t ruc tures , or reduce i t to a point tha t i t can be control led economically bythe drainage i n s t a l l a t ions . Control i s accomplished by dr i l l ing and groutingone or more l ines of grout holes in the foundation, usually para l l e l to thealignment of the dam or normal to the direc t ion of water movement. A bar r i e rto the movement of water in the foundation i s constructed by f i l l i n g the voidsor water passageways with grout . In theory, the bar r i e r needs only to be acur ta in of moderate width. In prac t i ce , however the bar r i e r obtained wil l bewider than necessary in some places and levels , and p o s ~ i l ynot wide enougha t others .

2) The holes for cur ta in grouting may be dr i l l ed on e i the r a s inglel ine or a mult ip le- l ine arrangement. The grouting of a s ingle l i ne of holeswil l ord inar i ly provide a sa t i s f ac to ry curtain for concrete dams t ha t are cons t ruc ted on competent rock. The grout cur ta in i s commonly loca ted as far upstream as possible in these cases. The exact locat ion of the cur ta in i s determined by the type of s t ruc ture as well as by the foundation condit ionspecul ia r to the s i t e s . The grout curtain for dams constructed on i n fe r io rrock may consist of a mult ip le- l ine arrangement of grouted holes Figures 7-1and 7-2). The holes in adjacent rows in a mult ip le- l ine arrangement should bestaggered with r e l a t ion to each other. A t r i p l e l i ne cur ta in should be ins ta l led in the following sequence: i n s t a l l ei ther the upstream or downstreaml i ne , then the other; and las t ly the center l i ne . Distances between l ines mayvary according to f i e ld condi t ions , bu t general ly wi l l not exceed 5 f ee t . Forembankment dams a mul t ip le l i ne should be considered in the upper zone beneaththe impervious core. I f solut ioned rock i s present , or where j o in t s or. f i s -sures are f ine , closely spaced, and e r r a t i c a mult ip le- l ine cur ta in may needto be constructed to the fu l l depth. A- s ing le - l ine cur ta in i s general ly usedfor rim or upland grouting. However speci f ica t ions should be f lex ib le enoughto add addi t iona l l ines of grout holes a t any locat ion or depth as determinednecessary in the f i e ld .

4-6

8/13/2019 EM_1110-2-3506

31/159

M 1110-2-3506~ ~

(3) Curtain grout holes m y be ver t i ca l , incl ined, horizontal , or anycombination thereof as discussed in paragraph 4-4. Grout curtains under em-bankment d ms are general ly located in a cutoff t rench close to the embankment

impervious core center l ine . Designs requi r ing an upstream locat ion must cons ider the poss ib le need for future grouting and the frequency of high poolsblocking access. Locations downstream of the impervious sect ion increase upl i f t pressures under the core. A good procedure a t abutments i s to inc l inethe holes with a component into the abutment. Horizontal grout holes aresometimes very effec t ive for grouting high angle fractures of l imited ver t i ca lextent . The depths to which grout holes are dr i l led should be governed by thehydrostat ic head to which the foundation wil l be subjected and by the geologicconditions in the foundation such as the depths of impervious rock. Depthsfor a grout cur ta in should be such t ha t the seepage path i s long enough tooffer su ff i c i en t resis tance to seepage and to prevent the occurrence of highex i t gradients near the downstream toe or excessively high u p l i f t pressureunder the downstream port ion of the dam. Grout holes should bottom in sound,

r e l a t ive ly impervious rock where possible. Final depths should never be basedon precedent . A rule of thumb often used for prel iminary planning of holedepth i s two-thirds the hydraulic height of the dam. Foundation rock permeab i l i ty usual ly decreases with depth. Grouting done from the foundation surface, such as for embankment dams should use low or near gravity pressuresfor the upper zone. Grouting through an embankment i s sometimes necessary forremedial or deferred grouting. Special precautions should be taken in thesecases to avoid fracturing or eroding the embankment. Grouting through a fewfee t of f i l l i s sometimes required to protec t sens i t ive mater ia l s or forwinter grouting to insula te the foundation and the freshly placed grout nearthe surface. In these cases, a good prac t ice i s to remove the f i l l and perform f ina l foundation prepara t ion a f t e r the grouting. Grouting of sens i t ivefoundations i s sometimes accomplished before excavation of the f ina l 2 or

3 fee t to l imi t freezing or exposure damage.

(4) Grouting from gal ler ies i s normally done a f t e r the s t ruc ture i s nearcompletion to take advantage of the surcharge so t ha t higher pressures m y beused. Dri l l ing for drains should not be done un t i l a f t e r grouting i s f inished.

c. Area Grouting.

(1) Area grouting usually consists of grouting a shallow zone in a part i cu la r area u t i l i z ing holes arranged in a pat te rn or grid. The grout ing i sdone (a) to increase the supporting capaci ty of the rock or (b) to preventunderflow through weathered or par t i a l ly dis in tegra ted rock, highly fracturedrock, or hor izonta l ly s t r t i f i e d rock where cur ta in grouting would not be suff ic ient ly effec t ive . The grout ing operat ion in the f i r s t instance i s oftencal led ' 'consolidat ion grouting. Grouting in the second instance merges intomul t ip le- l ine cur ta in grouting. Deeper area grout ing i s sometimes done togrout speci f ic geologic condit ions, such as f au l t zones, or to consolidate subsurface materials a t shaf ts or deep s t ruc tures . Area grout ing near the surface i s usually done with low or gravity pressures; however where deeper

4-7

8/13/2019 EM_1110-2-3506

32/159

EM 1110-2-35062 Jan B

zones are grouted, higher pressures can be used safe ly.

2) Area grout ing to increase the load-bearing capacity of foundation

rock is sometimes used as a means of sol id i fy ing seamy but otherwise good rockand thereby decreasing the amount of rock excavation and the amount of concrete backf i l l . However the effect iveness of area grouting i s questionableunder foundation conditions where the seams in the rock are f i l l e d with clay,and the clay must be removed before grout in jec t ion for consolidat ion groutingcan be effec t ive . Because of the i r regular pat te rn of the seams and the character of the f i l l i n g material , i t i s not possible to know how much of the clayactua l ly i s removed and consequently, how effec t ive the grout ing has been.

t wil l probably take less t ime, and may cost l e s s , to excavate broken andseamy rock ra ther than to t r e a t i t by grouting.

3) Treatment of s t r a t i f i e d or seamy rock may r e su l t in wasting a largequanti ty of grout through j o in t s and seams leading away from the foundation

area. This waste can be prevented by grout ing a l ine of holes on the peripheryof the area a t low pressure. Substantial savings may sometimes r e su l t fromtaking these precautions.

d. Tunnel Grouting.

1) Grout treatment for tunnels may be for backpacking tunnel l i ne r s ,consolidat ion of material surrounding the bore, seepage cont ro l , contactgrouting, or r ing grouting. Preexcavation grout ing may be required for consol ida t ion and water cont ro l . o accomplish grout ing a f t e r tunnel excavat ion,imbedded pipes or formed holes are provided through the l i ne r, i f necessary.Pressure grouting for backpacking behind cas t - in-p lace concrete l i ne r s shouldnot be done un t i l 7 days a f t e r the placement of the l i ne r. However whereprecas t concrete or s t ee l r ing l i ne r s are used, grout ing should be accompl i shed as quickly as possible a f t e r l i ne r placement. A sanded mixture i snormally required for grout ing behind tunnel l i ne r s . In jec t ion begins a t theinver t and i s moved up as grouting proceeds. The f ina l step i s contact grouting with neat cement grout a t the crown a f t e r the l i ne r grouting has been comple ted and the grout has aged and shrunk.

2) Ring cur ta in grout ing i s a treatment akin to curtain grout ing undera dam in tha t i t forms a grout bar r i e r intended to reduce the poss ib i l i t y ofwater percola t ing from the reservoi r along the tunnel bore. The stagegrout ing method usual ly wi l l produce the bes t r e su l t s .

3) The necess i ty for grout r ings, the number of r ings required, and thedepth and the spacing of holes in the r ings a l l depend upon the type and theconditions of the rock through which the tunnel i s excavated and the an t i c ipated hydros ta t ic head t ha t wi l l tend to develop seepage through the rock.The r ings commonly are located on the extended l i ne of the grout cur ta in underthe dam. Where the rock i s f a i r ly t igh t , however grout r ings may funct ion

4-8

8/13/2019 EM_1110-2-3506

33/159

M 1110-2-350620 Jar, 84

more eff ic ient ly i f they are only a short distance downstream from the controlstructure location.

4) The crout r incs aref o ~ e

by dr i l l inc and crouting four or moreboles equally spaced around the tunnel bore. Spl i t spacing procedures shouldbe used when there is significant crout take. Where multiple rinc treatmentis required, boles in the alternate rincs should be staggered radia l ly. Therings should be as far as practicable from the transverse jo in t s of the l ining,especially i f the jo ints do not contain water or grout stops, because leakageof grout from the jo in t s may be di ff icu l t to control .

5) For consolidation grouting or water control the boles generallyshould extend into the rock well beyond any fracturing that may have beencaused by tunnel driving and should intercept as many natural fractures, solut ion openings, and similar imperfections as possible.

e. Cavity Fil l ing.1) Cavity f i l l ing i s one of the leas t standarized types of grouting.

The effectiveness of crouting a clay-f i l led cavity i s questionable; however,a i r - or water-fi l led cavit ies or larce , open jo in t s can successfully becrouted with cement crout. The extent of a cavity i s not known af te r the penet ra t ion of a sincle crout hole. ore exploration or dr i l l ing may be necessarybefore treatment can be d e t e ~ i n e dA thick, tremied grout, grouting of preplaced accregate, or other materials requiring special ized mixtures may berequired.

2) When a cavity i s encountered in dri l l ing, the bole should be grouted.A sanded mixture i s normally required to complete the grouting of the cavity.Intermittent groutinc may be necessary.

3) Intermittent grouting i s the process of injecting some amount ofcrout in to the hole and waiting several hours before injecting more grout.Several waiting periods may be necessary. During each injection period thel a s t batch of thick mortar grout injected into the hole should be followed bythe in ject ion of water into the hole through the pump system. Grouting shouldresume, af te r the waiting period, with neat cement grout before returning toinject ion of the mortar mix. The amount of grout to be injected during eachperiod i s normally a predetermined l imi t . The maximum amount of grout to beinjected into a cavity through a single hole should also be predetermined before considering other procedures.

4) When refusal i s reached, i t i s assumed that grout bas a t l eas tf i l l ed the portion of the cavity penetrated by the grout bole. Additionalgrout holes are then dri l led and grouted unt i l the desired resul ts areachieved.

5) f pressures f a i l to build up or the cavity is obviously too large

4-9

8/13/2019 EM_1110-2-3506

34/159

M 1110-2-350620 Jan 84

to grout in t h i s manner grouting should continue beyond the cavity. Addit ional explorat ion, consultat ion, evaluat ion, and design of remedial measurescan then take place without delaying the contractor. These measures m y ca l l

for special ized grouting procedures or materials such as foaming agents , posit ive cutoff diaphragm or formed concrete wall , addit ional excavation, or someother solution. Tremie or gravity grouting i s a method often successfullyused to grout cavi t ies or large voids.

f . Backfi l l ing Boreholes.

(1) Backfi l l ing boreholes and grout holes are an important par t of thegrouting program. These holes m y act l ike r e l i e f wells under the reservoi rhead, and i f not properly grouted, they could contribute to seepage and piping.Holes in the rock foundation should be backf i l led with grout t ha t has a watercement ra t io of 1.0 to 0.7 and about 4 percent bentonite. A minimum diameter,l - inch delivery l ine with a s t ee l section a t the end i s extended to the bottom

of the hole af te r the l ine is completely fu l l of grout. Grout i s then pumpedun t i l i t flows from the hole, and the delivery l ine i s slowly withdrawn whilepumping continues. I f set t lement of grout occurs, tke holes are topped off orrebackfi l led before f i l l i s placed.

(2) The tremie method i s also used to backf i l l holes in embankments orf i l l ; however the backf i l l mix in these applicat ions i s designed to be morep las t i c .

g. Contact Grouting. Contact grouting i s the in jec t ion of neat cementgrout a t the contact of a concrete s t ruc ture with an adjacent surface. Cont ac t grouting f i l l s the void a t the contact t ha t resul ts from shrinkage. Cont ac t grouting m y be done through e i the r header pipes ins ta l led for t ha t purpose during construct ion, or d r i l l holes. The header pipes or grout holes arethoroughly washed before the grouting operat ion. Grouting pressures m y varybut the highest safe pressure should be used. Contact grouting i s a sealingoperat ion intended to bring about a fu l ly bonded contact between any concreteor s t ee l s t ruc ture and the adjacent rock. Shrinkage of the concrete as i tse t s or def lec t ion of the loaded s t ruc ture m y produce seepage paths along thecontact . Contact grouting i s advisable where such conditions are c r i t i c a lThis t reatment i s used most frequently in the abutment areas of concrete d msand in the crown areas of l ined tunnels in rock. The grouting i s usually donein both instances af te r the main s t ruc ture has been completed. A typica lpiping arrangement for contact grouting i s shown in f igure 4-1.

h. Soi l Grouting. The methods described in a through g, above, were developed primari ly for grouting rock, and m y or m y not be applicable forgrouting so i l . Soi l grouting i s usually conducted to reduce or a r r e s t watermovement and/or for increasing the bearing load of the s o i l , to reduce s e t t l e -ment, and to improve res is tance of so i l to erosion by water and/or ra in . Theterm so i l i s used here in the broadest sense, and includes unconsolidatedgranular materials ranging from clays with increasing coarseness through f ine ,

4-10

8/13/2019 EM_1110-2-3506

35/159

Rfllum ltne, biDcll s ' ' pipto neoresl gallry

~ . r dia. black SIHIp pf rtSflrS

Grout supply line,SIZe WI/I ~ r yWlfhn u m b If hoi s

RiS

PIPING SYSTEM

- - - - G r o u t

M 1110 2 3506

2 Jan 8

H.Od . , PIPfiSdiOiflflfer OSr e q u ~ r f l d

i ~ ~ i l J ~ H ~ ; ; ; ~ ~ ~ ~ ~ ~ ~ i } : / : : : : : O O D i m W ~ s i o n sof Dnchor hole ands l . l bDr lo bfl d, , . ,minfldliT f1. ld cDndillons.

4 Round elect,;cDI twllf lfIIDII ~

-----w;

DETAIL O GROUT OUTLET

Figure 4 1. Deta i l of contact surface grouting

4 11

8/13/2019 EM_1110-2-3506

36/159

M 1110-2-350620 Jan 84

medium and coarse s i l t s ; f ine , medium and coarse sands; and up to and including f ine grave ls . A method for determining the l imi ts of grou tab i l i t y forthe coarser granular s o i l s i . e . medium sands through f ine gravels , i s described

inparagraph 5-2e. Treatment of f ine granular mater ia l s , i . e .

through coarse s i l t s i s covered in M 1110-2-3504. Methods of so i l grout ingare summarized as follows:

1) Casing. A casing m y be dr i l l ed , j e