Disclosure to Promote the Right To Information

Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public.

इंटरनेट मानक

“!ान $ एक न' भारत का +नम-ण”Satyanarayan Gangaram Pitroda

“Invent a New India Using Knowledge”

“प0रा1 को छोड न' 5 तरफ”Jawaharlal Nehru

“Step Out From the Old to the New”

“जान1 का अ+धकार, जी1 का अ+धकार”Mazdoor Kisan Shakti Sangathan

“The Right to Information, The Right to Live”

“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता है”Bhartṛhari—Nītiśatakam

“Knowledge is such a treasure which cannot be stolen”

“Invent a New India Using Knowledge”

है”ह”ह

IS 6066 (1994): Pressure grouting of rock foundations inriver valley projects - Recommendations [WRD 8: Foundationand Substructures]

March 1994

IS· 6068 : 1994(RMfftnned 2004)

~mtT~31T 1l~ -.tcrr Cfij Gfij

~-~

( 'iff'?! ~erur)

Indian Standard

· PRESSURE GROUTING OF ROCKFOUNDATIONS IN.RIVER VALLEY

PROJECTS - RECOMMENDATIONS

( Second Revision)First Reprint AUGUST2006

(Including Amendment No. I )

UDC 621.81 : 624.159.4: 666.972.031.14

C DIS 1994

B UREA U OF INDIAN" ST AN,DARDS "MAN'AK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEWDELHI 110002

Price Groul) 7

. "'

AMENDMENT NO. 1 JANUARY 2005TO

IS 6066: 1994 PRESSURE GROUTING OFROCK FOUNDATIONS IN RIVER VALLEY

PROJECTS - RECOMMENDATIONS

( Second Revision)

( Page 2, clause 4.1, first line) - Substitute 'inter' for 'nter'.

[ Page 5, clause 8.3(a), second sentence ] - Substitute the followingsentence for the existing:

'Whenever early strength is desired in grouting jobs, pozzolanas may be treatedas inert non-cementing fillers. t

(WRD 8)Printed at : PrabhatOffset Press.NewDelhi-2

PouaclatioD and Sub-Structures Sectional Committee. IlVD 8

FOREWORD

This Indian Standard ( Second Revision) was adopted by the Bureau of Indian Standards, after thedraft finalized by tbe Foundation and Sub-structures Sectional Committee had been approved by theRiver Valley Division Council.

The treatment of rock foundations by pressure grouting is an art of applying the knowledge of localleolo8Y and certain ~sic principles, .cov~rin8 groutpenetratlon ~nd travel, t!' the specific requirementsof a job. The success of a grouting Job depends on a coordinated handling of all the technical andorganizational aspects of the work comprising exploration, establishing design requirements, initialtrials, field control and flnal testinl and evaluation. It wou d be futile to prepare a rigid set of rulesor stipulate standard procedures which can be enforced without leaving any latitude for the exerciseof discretion by the site engineer, The aim of these recommendations is to summarize well known andproved prinCiples and to describe commonly used procedures, equipment and techniques in order toenable an engineer-in-charge of a grouting job to provide guidelines for a specific case. The need forfollowin, an experimental approach and learning through trial is emphasized while providing guidelineswhich would permit a site engineer to use his discretion without compromising the overall designrequirements. This standard has been formulated to give guidance in this regard.

This standard was first published in.1971 and was revised in 1984. Based on experience gained in theuse of this standard this further revision was taken up. The salient changes made in this revision areproviding the guidelines for testing the efficacy of the grouting operation besides updating other provi­SiODS in Usht or latest Indian Standards.

For the purpose of deciding whether a particular requirement of this standard is complied with, thefinal value, observed or calculated, expressing the result of a test or analysis, shall be rounded off inaccordance with is 2: 1960 'Rules for rounding off numerical values (,e,;s~d j', The number ofsipificaat places retained in the rounded off value should be the same as that of the specified value inthis standard.

IS 6066 : 1994

Indian Standard

PRESSURE GROUTING OF ROCKFOUNDATIONS IN RIVER VALLEYPROJBCTS- RECOMMENDATIONS

( Second Revision)do not occur which are liable to impair theefficiency of the drainage system.

3.1 Before arrivin, at design requirements forany job the prrmary objectives should bedefined, for example, reduction of rock defor­mability, etc. The depth, spacing and patternof grout holes, the choice of method of grout­iDS, materials injected and consumption limitsas well as controls on pressure depend on theobjectives as described in 3.1. These controlsand criteria would have to be established bytrials and it is desirable to establish the pro.gramme of trials at the initial stales of thework.

3.3 The criterion given in 3.3.1 and 3.3.2 aresuggested for deciding whether or not to groutany portion or zone of rock. Overall designrequirement, importance of the structure andthe value of water as well as geologicalconditions should also be taken into considera­tion.

3.3.1 To Sa!e,uard ,Ite Foundation AgainstErodibi/ity Haztlrtb

The limiting lugeon values' given in Table 1 arerecommended for deciding the necessity orotberwise of grouting, Lugeoe values in excessof those given in the table would indicate thatJroutinl is desirable. ·

Tole 1 Suuested Llmitl•• LUleo. Values. Irom Erodibility CODllderatlo.

Rock Below Rock Be'owe.tolf TreDda M......,DuI

S to JO S to 7

3 to.s 3 to S

I to 3 J to 3

1 to 3 I to 3

1 SCOPE

. This standard lays down recommendations forpressure grouting of rock by cement with andwithout suitable admixtures and fillers, applica­ble to curtain and consolidation grouting gener­ally used in River Valley Projects.

2 RERRENCES

The Indian Standards listed in Annex .~ arenecessary adjuncts to this standard.

3 GENERAL

3.1 Pressure grouting of rock foundations isnormally carried out to fill discontinuities,cavities or voids in rock mass by suitablematerials. The grouting programme should aimat satisfying the design requirements economi­callyand in conformity with the rest of theconstruction schedule. The design requirementsfor adopting a srouting programme are asunder- The parameters will depend OD the typeof structure.

A) Curtain grou,ing

i) To safe,uar~ the foundation againsterodibihty hazard, and/or

ii) To reduce quantity of seepage.

D) COIIIolidtJtloll ,rou'''''iii) To reduce the deformability of

jointed or shattered rock.

3.1.1 Even tboulb the overall objective is toreduce the permeability of the rock founda­tion, the relative emphasis between control ofthe rate of seepage and control of uplift depends .OD the value of the water stored and the natureof foundation strata. In cavernous and hiahlyjointed rocks the reduction of the rate ofseepa.e may be an important safety considera­tion. On the other hand in massive relativelyunweathered rocks, the quantity of seepage maynot be of consequence, as 10Dg as the desiredreduction in uplift rressure is achieved. In suchcases, uplift contro may be achieved primarilyby drainage while the aim of grouting would beto ensure that local concentrations of seepage

.1

Itt.

Group ALaminar Bow

Group BTurbulent Flow

Group CDilation

GroupOWashout andHydraulic frac­turin.

Group EVoid fill

3 to S 3 to 5

IS 6066: 19N

3.3.2 To Reduce Quantity. of Seepage:

i) For dams exceeding 30 m height. curtain. grouting should be carried out when the

water absorption exceeds one lugeon.

ii) For dams under 30 m height, curtaingrouting should be carried out where thewater absorption exceeds 3 lugeon.

4 COORDINATION WITH OTHERCONSTRUCTION ACfIVITIES

4.1 Grouting operations are generally nter­dependent with other construction operations;for example, excavation and blastina in thevicinity of the area that is being grouted maycause leakage of grout and render the groutingoperation ineffective or it may be necessary tocomplete the aroutina operations to enable astart to be made of other operations, such asconcreting or masonry work. Sometimes it maybe necessary to carry out grouting beforeremoval of the overburden to obtain the neces­sary load of surcharge over the zone required tobe grouted. In other cases removal of theoverburden may benecessary to facilitate sealingof the cracks prior to grouting. Draining bolesshould always be drilled only after grouting iscompleted within the expected distance ofgrout travel. Generally, It is preferable tocomplete blasting before taking up groutingoperations. ]f blasting after grouting is unavoid­able, thorough testing and regrouting isessential after blasting.4.2 A drainage and grouting gallery is a com­monly used device to facilitate grouting afterplacing the masonry or concrete in the founda­tion and ensuring that the necessary cover ofconcrete is obtained. to enable the desiredgrouting pressures to be developed. Sometimesholes are dri lied in the foundation and 01 pipesleft in place, through the masonry or concrete.and the foundation grouted through these pipeslater.4.3 It is difficult to make general stipulationsregarding the coordination of grouting withother construction activities, but it would beevident from the above that careful planning ofall associated construction activities, such asexcavation, concreting, fill placement, drillingof drainage holes and their coordination withgrouting is essential for successful execution of'the grouting programme.

S RELATION OF GEOLOGY TO GROUTING,THE IMPORTANCE OF FOUNDATIONEXPLORATION AND INITIALEXPERIMENTATION

~.l Reliable geological interpretation of thetype, distribution, approximate size and directionof discontinurties, voids, cavities, etc, in thefoundation rock is necessary prior to grouting.

2

5.1.1 The sub-surface conditions should be in­vestigated by core drilling a number of holes inthe foundation area. Percolation tests shouldbe conducted in the holes within the open areaof the foundat ion charted for use in plan n ingthe grout treatment. When investigation holeshave served their purpose, they should becompletely filled with grout (see IS 5313 :1980 ).

5.1.2 The grouting programme should be con­ducted in such a manner that the initial experl-.mentation generally covers all the typicalgeological situations.

5.1.3 The depth, spacing and orientation ofgrout holes should be related to the geologicalfeatures; for example, inclined holes should bepreferred when the rock permeability is primarilydue to closely spaced vertical/sub-verticalsystem of joints. It is sometimes necessary toevolve a pattern of holes consisting of differentsets of holes appropriate to each type of dis­continuity, such as bedding planes, system ofjoints and lava contacts.

6 GROUTING METHODS

6.0 Rock grouting consists essentially of drillinga series of grout holes in rock and injectinggrout under pressure, which eventually sets inthe openings and voids in the rock. The drillingand grouting operations can be carried outeither to the full depth in one operation or insuccessive depths either by stage grouting or bypacker grouting.

Grouting in the valley should proceed from riverbed towards abutments.

6.1 Fall Depth Groutlog

In the full depth method each hole is drilled tothe full desired depth, washed, pressure testedand grouted in one operation. This method isusually limited to short holes, S m or less indepth, or boles up to 10 mtbat have only smallcracks and joints with no risk of surface leakage.In deep bore holes high grouting pressureshave to be used to achieve proper penetrationof the grout at an economic spacing of holes.As full depth grouting involves the risk of dis­turbance in the upper elevations, it is notgenerally considered suitable for arouting deepholes. For grouting in heterogeneous strata,where the nature of rock discontinuities issubject to large variations in relation to thedepth, full depth grouting is not recommendedand stage grouting is preferred to packer grout­iog in such cases.

6.2 Sta.e Groutl_.

6.2.1 Stage "outing is conducted to permittreatment 0 various zones individually, bygrouting successively increasing depths. alter

sealing the upper zones. Stage grouting, indescending stages, can be carried out by adopt­ina the procedure given below.

(1.2.2 Grouting is done by drilling the holes toa predetermined depth and grouting this initialdepth at an appropriate pressure. Grout is thenwashed from the hole prior to its final set( within 2-4 hours) and the hole deepened forthe next stage. Alternatively the grout is allow­ed to harden and redrilling is carried outthrough the hardened grout and the hole exten­ded to the next stage. In another procedurecalled the one stage redrilled method, which issometimes used, grout is washed out within asmall depth of the top of the stage being groutedand only one stage is redriJled for proceedingto the next stale. In each of the aboveprocedures the cycle of drilling-grouting-wasb-

.mg or redrilling is repeated until the requireddepth of the hole is reached.

6.2.3 For stage grouting. the connection at thetop of the hole can be made directly to theheader or by seating a packer at the top of thehole in the casing pipe. Alternatively, it issometimes advantageous to install a packerimmediately above the stage that is beinggrouted in order to isolate the upper portion ofthe hole. Higher pressures can then be permit­ted for grouting of the lower stage withoutcausing upheaval in the higher stages.

6.2.4 An alternative procedure would be towithdraw the grout pipe, after completing thegrouting operation, by a distance equal to thedepth of the stage grouted. After the initial setoccurs, that is, about half an hour, the portionof the hole above the stage grouted may bewashed. In this method the grout sets in thelength of one stage, and it is necessary to redrillone stage before proceeding with furthergrouting. It is more convenient to install thepacker at the top of the hole when one-stageredrilling procedure is adopted.

6.1.5 Grouting with double packer is suitablewhere a few well defined seams or zones existand the packers can be seated above and belowsuch zones. Rotary drllling method is preferredwhen double packers are used.

6.1.6 When packers can be seated and there isno risk of upheaval, grouting can be carriedout with single packer in ascending stages.

6.2.7 However, in many cases packers mayfunction yet grout may overtravel and causeupheaval in the zones above the section beinggrouted. The method of stage grouting in des­cending order is therefore a more dependablemethod for badly jointed and fissured stratavulnerable to upheaval.

3

6.1.8 In relatively compact rocks it may be moreconvenient to seat the packer at the top of thestale being grouted. The hole may then bewashed, as soon as the period of initial set ofcement is over. to the entire depth of the holeup to the bottom of the stage in progress.

6.2.9 On the other hand in strata vulnerable toupheaval, it may be necessary to allow thegrout to set and form a sheath around the holein order to enable hi,h pressures to be used inthe lower portions 0 the hole. In such cases,the washing and single stage redrilling proce­dure would have to be adopted.

7 PATTERN AND DEPTH OF HOLES ANDSEQUENCE OF GROUTING

7.0 The pattern and depth of holes is governedprimarily by the design requirements and thenature. of. the rock. When the purpose isconsolidation, the holes are arranged in a regularpattern over the entire surface area required tobe strengthened and the depth is determined bythe extent of broken rock as well as the structu­ral requirements regarding the deformabilityand strength of the foundation. When thepurpose is impermeablllzation, the grout holesat e arranged in a series of lines to form acurtain approximately perpendicular to thodirection of seepage. The depth of holes isdependent on design considerations as also onthe depth of pervious rock and the configurationof zones of relatively impervious strata.

7.0.1 The size of grout holes is generally lessImportant than the cost of drilling holes and thecontrol of inclination. For grouting withcement, 38 mm holes are used. '[he advantagegained by drilling large holes does not oftenjustify the increase in drilling costs. In longholes the diameter at the top of the holes mayhave to be larger than the final. diameter at thebottom of the hole to facilitate telescoping orto allow for the wear of the bit.

7.1 Patteros of Holes for Curt.iD Grouting

7.1.1 Single Line Grollt Curtains

Single line. grout cu~tains are effective only inrocks having a faIrly regular network of dis­cODti.Quities with reasonably uniform size ofopenIngs. In suc~ cases a curtain of adequateWidth can be achieved by grouting a single lineof holes. In massive rocks with fine fissuresuplift control is primarily achieved by drainag~and the grout curtain is used only as a supple­mentary measure to avoid concentrations ofseeJ?8ge which may.excee~ the capacity of thedr!Lln~ge.system.. Sl~gle !lne curtain may servethis limited. objective In comparatively tightrock formations.

IS ,.: 1994

7.1.1.1 In single line curtains it is c!Jslolnal'Y todrill a widely spaced system of primary h~lcs,subscquen tly followed by secondary and. tert!aryholes at a progressively smaller spacing. Iheusual practice is to split the spacing fromprimary to the secondary ~nd. secondar~ . totertiary phase. One of the crtterra for decidingon the primary spacing is the length of expectedintercommunication of grout between holes.The initial spacing usually varies between6 m to 12 m but the choice of spacing should bebased on the geologlcal conditions and .onexperience. At every phase of . the groutingoperation, the results of percolation tests a!'dgrout absorption data should .be compare d w.lththe previous set of holes In order to decidewhether a further splitting of the spacing ofholes is worthwhile. When no significant improve­ment is noticed either in terms of decrease ofthe grout absorption or water percolation, care­ful review should be made of the rock features,the nature of the rock and its relations to thepatterns of holes. Sometimes it may be moreadvantageous to drill another line of holes at adifferent angle and orientation than to spht thespacing further. Spacings below one metre arerarely necessary and the requirement. of. a spac­ing closer than one. metre may ~Cte~ Indicate anunsuitable orientation and inclination of holes.Possibly multiple line curtains may be.necessary.If the area is too limited, the setting time of .thegrout becomes important since it is not desira­ble to drill too close to a freshly grouted hole.Before pressure grouting is started, drilling of allthe holes should be completed within a distanceof 20 m of the hole to be grouted.

7.1.1.1 Depen.ding upon initial investigation andstrata conditions the spacing of primary holetreatment should be decided. If the primaryholes were spaced more than 6 m apart second­ary holes should. be drilled and grouted. Oncompletion of primary holes spaced ~Ioser

than 6 m or secondary holes ( when the pnmaryholes are spaced more than 6 m ), should thepercolation tests carried out in a few test holesindicate that further grouting of the area isnecessary, secondary or tertiary treatment, asthe case may be, should be carried out sy~tem­

atically thereafter in the whole area or In theparticular section where the rock conditions arebad. Similarly tertiary holes should be takenover the whole area or the full length of thesection which requires the treatment.

7.1.1.3 In addition to the systematic grouting ofprimary secondary or tertiary and subsequentboles it' may be necessary to drill and groutadditional holes for treatment of peculiargeological features. such as faults, shear zonesand weathered rock seams.

7.1.2 /tIl/II/pie Line Grout Curtclns

ln rocks with a wide range of sizes or openings.cavities and discontinuities which are irregularlydistributed, a single line curtain may not beeffective. The larger openings may absorb ex­cessive volumes of grout. if high pressures. andthin grouts are used. On the other hand thickergrouts ( 1 : 1 or thicker, or grouts with fillers)used for sealing the larger openings m~y bl.ockthe sides of holes and prevent penetration Intofiner cracks. In such cases it may be advantage­ous to use a multiple line curtain consisting. of'outer lines which are drilled and grouted Ini­tially with thicker grouts. It may sometimes bedifficult to treat the outer rows of holes torefusal and grouting may have to be stopJ?Cdafter injecting a limiting volume .of grout ,,!hlchmay be arrived at on the basis of eX~erJeDCeand/or initial trials. Af!er completln.g thegrouting of outer holes, intermediate hoe, orlines of holes may be drilled and grouted atcomParatively higher pressure with t~inn~rgrouts. Grouting of the outer rows which IScarried out initially facilitates confinement ofgrout and thus ensures effective subsequenttreatment of inner cracks at higher pressurethrough the cent.ral row or rows of holes. Thefinal spacing of I.noer. and outer rows may. bedifferent in a multiple line pattern, the spacingin each row being governed by the nature ofrock discontinuity, intended to be treated bythe particular row. In any case in the centralrow the split spacing method .should be f~llovyeduntil the desired degree of Impermeabillzationis achieved. .

7.2 Patter. of Holes for CouolldatloD Groatl_.7.1.1 The choice of pattern of holes, for con­solidation grouting depends on whether it isnecessary to wash and jet the bole systematic­ally ( see 10.4 ). When washing has to be carriedout a hexagonal pattern ( see Fig. 1 ) would bepreferred as this. admits for .fto~ reYe~sal. Whensystematic washing and 'Jettlng IS carried out toremove all soft material in seams it is generallynot necessary to use a primary and secondarysystem of holes.

7.2.2 When it is desirable to test the efficacyof consolidation grouting by comparing thegrout absorption in primary and secondaryholes a rectangular or square pattern (leeFil. I) of holes would be preferred. This isgenerally the case when the joints are irre,ularand relatively free from in-filling or it is notnecessary to remove the material filling thejoints.

7.3 Seqaeace of GroutlD.

7.3.1 While carrying out grouting operations itis necessary to ensure that no hole is drilled so

IS "": 19M

'" [TOP OF DAM~ ~ GROUND SURFACE ..

" INSPECTION GROUTING AND «»: - ~ ., ,~-- .'

'., DRAINAGE GALLERY • ~ ....... CONCRETE : ~. '...~. . ~ .':. . ." ~I ~ ~PAD OPTIONAL .;.~ •.' .'~' .•....~ ~~ ~.... ' ...'iiJHlu: - - - - - I iill4fJt t~ ifJ. \- ::'"; >:::.0;:;:.:, .." .,LI',r,_ 'c,tJ,......n ijJ...i;, . ' ~ y F'

'l-''"-H - -- ..-yIJ t ,... ,,; , J

L l........ - ~- .1, r.J.. J ANGLING OF HOLES I 'I--1; __ L- DEPENDS ON JOINTING' '''I /DRAIN HOLESLFIRM ROCK LINE I-;- AND STEEPNESS OF : :; \'~ VERTICAL DRAIN HOLES

THIRD ZONE X ABUTMENT I:~WITH ALTERNATE .I ~UPSTREAM CURTAIN

SECOND ZONE ALTERNATE CURTAIN FOR~FIRST ZONE LESS THAN 80m HIGH' GROUT CURTAIN

SECtION Xl1A Typical Profile of Curtain Grout Holes

SECONDARYPRIMARY

'.

Ii JI----&--~~~~--+----+-#__-+-~---t

• 0i---&.M~~~-'-""'~I-I-_-""'-+-+"""'-+-_IIIUZ~ 3ena

DISTANCE IN METRE

SQU~E PAlTERN

1B Consolidation Grouting

FIG. 1 PATTIRNS 0'GR.OUT HOLIS

HEXAGONAL PATTERN

8 GROUT MIXTURE

8.1 Rock grouting is usually performed with amixture of cement and water with or withoutadditives.

8.2 The cement generally used is any of thefollowing:

i) Ordinary Portland - IS 269: 1989 or· IS 8112 : 1989 or

IS 12269: 1987

ii) Portland Pozzolana - IS 1489( Part 1 ) : 1991,( Part 1 ) : 1991

- IS 455 : 1989

- IS 6909 : 1990

iii) Portland Slag

iv) SupersulpJatedCement

v) Sulphate Resisting - IS 12330 :. 1988Portland

8.3 Other solid materials may be used as additi­ves to the grout mixture among which are thefollowing:

a) Pozzo}anas, such as fly ash ( see IS 3812 :1981 ) and calcined shale ( see IS 1344 :1981). As early strength is important onmost groutinB jobs, the pozzolanas may

close to a bole being grouted that inter connec­tions develop. Spacing between primary boles isgenerally so selected that the drilling could becarried out without interference from groutingdue to inter-connections from adjoining ho leseSometimes a situation arises when drilling ofupper stages of secondary holes may be inprogress concurrently with the grouting of thedeeper stages of primary holes. In such cases,inter-connections would not be prevented if asufficient cover of rock is not available betweenthe portion which is being grouted and the zonein which the drilling of secondary holes may bein progress. As a rule the drilling of secondaryholes in any zone of the foundation shall not betaken up until sufficient cushion of alreadygrouted stages of primary holes in the samearea is not available.

7.3.2 In multiple line curtains relative sequenceof outer and inner rows shall also be strictlyfollowed as described in 7.1.%.

7.3.3 When grouting in rock overlain by pervi­ous soil it is necessary to complete grouting ofthe contact zones of the rock and soil beforecommencing the grouting of the rock otherwisethe grout would escape into the soil and it maynot be possible to control or detect excessiveleakage.

5

,

IS 'OM: 19M

behave only as inert non-cementingfillers.

b) Fine sands ( see IS 383 : 1970) are aneconomical material widely used in grout­ing. The use of coarse sanded grout mix­tures is particularly advisable when largevoids or cavities are to be grouted.

c) Other fine non-cementitlous materials likebentonite ( S~. IS 12.S84 ': 1989) clay andsilt may also be used. These materialsadd to the b~ of the grout mixture andreduce the cost but also reduce thestrength and may reduce the watertight­ness of the hardened grout. However t

bentonite when used in small quantitiesoffers certain advantages in reducingbleeding and segregation.

8.3.1 While usina additives, constant fieldchecks and review should be undertaken toachieve the desired resul ts in respect to perme­ability and strength.

&.4 Ad.txtares

Admixtures when added in small quantities tothe grout mixture impart certain desirablecharacteristics like delaying or hastening thesetting time and increasing the workability( see IS 9103 : 1979 ).

8.5 Water

The water for grout mixtures should be cleanand generally free from organic material thatwould affect hardening or durability. A sampleshould be tested to determine if the watercontains any deleterious materials.

8.5.1 Where the grouting is being done belowthe ground water table, the ground water shouldbe analyzed for its salt contents and pH value.which may affect the rigidity and thixotropy ofthe lI'0ut.

1.6 The arout should fulfil the following require­ments whatever be the constituents used andtheir proportions:

a) The set product should have desiredstrength to resist extrusion under thehydrostatic nressure to which' the curtainwill be subjected;

b) When grouting for consolidation. the setproduct should have desired ItrCDltb;

c) The set product should have a sufficientdegree of permanence to satisfy the requi­rements of the site. On important jobsproducts of proven long-term performanceshould be used; and

d) Particles in the liquids should be smallenough to penetrate the pore spaces ofencountered fissures.

9 DRILLING AND GROUTING EQUIPMENT

'.1 DrilUaI £fIulpaent9.1.1 The equipment should be capable of drill­ing holes of sizes described in 7 and to therequired depths. The equipment should becapable of providing a continuous water or airlush of adequate capacity.

9.1.2 The various types of drilling equipmentcan be grouped as under:

a) Percusllve drilling 'fulpme"t:

i) Standard drifter or wagon drilJ;

ii) Down the hole drilling equipment; and

iii) Overburden drilling equipment.

b) Rotary drilling equipment with suitabledrive, that is, hydraulic, electric, diesel orcompressed air.

9.1.2.1 Percussive drilling methods are generallymore economical in aU types of rocks. For deepholes it may be advantageous to use overburdendrilling equipment. By virtue of the separaterotation drive, greater speed and economy canbe achieved, also by virtue of the greater rigidityof casing tube combined with the drill rods,better control on inclination of holes cangenerally be achieved in the overburden drillingequipment. Down the hole hammer is also capa­ble of maintaining a better control on theinclination. Howevert the hammer may getclogged when the drill cuttings form slush insoft saturated strata and cannot be removed byair flushing.

9.1.3 During percussive drilling in stratifiedrocks where the resistance of the rocks is proneto variation the holes may get curved and con­trol on inclination may be lost. In such cases3Uide tubes may be used for ensuring verticalityof tbe holes or alternatively rotary drilliDI maybe used.

9.1.4 Irrespective of whether air or water isused for flushing the hole during drilling,thorough cleaning by water flushing is essentialbefore starting 8routiD&operations.

'.2 GroatlDI Eq81pmeat

The grouting equipment should meet thefollowinl requirements:

a) Be of sufficient size to meet the maximumdemand for grout;

b) Be capable of prolonged operation atanticipated maximum pressure;

c) Be of sufficiently rugged construction tominimize delays -from failure of essential

, parta;

d) Permit quick cleaning by washing; and

e) Provide quick access to key parts in caseof mechanical failure.

Continuity of operations is necessary not onlyfor ellciency, but also for effectiveness ofaroutiDI·

9.2.1 Grout Mix",The mixers should have two tanks namely mix­i~1 tank and agitating tank. Mixers are generallycylindrical in shape, with the axis eitherhorizontal or vertical and equipped with asystem of power-driven paddles for mixing.Grout should be mixed in a mixer operating atI 500 r.p.m, or more. The higb speed of mixinaserves the purpose of violently separatiDg eachcement grain from its neighbour thus permittingthorough wetting of every grain. This proves tobe advantageous by chemically activating eachgraln to thorough hydration before reaching itsfinal resting place. Further individuul grainspenetrate finer cracks more readily then ftocs.Vertical, barrel-type mixers have proved satis­factory when small mixers are required for usein confined or limited working spaces. This typeof mixer consists essentially of a vertical barrelhaving a shaft with blades for mixing, driven bya motor mounted on top of the mixer above thebarrel. Centrifugal pump mixers mix the groutby recirculating it through a high speed centri­fugal pump. They are sometimes referred to ascolloidal type mixers, but they do not achieve atrue colloidal grout mix. However, they possessconsiderable merit and produce grout of excel­lent texture. When mixing sand-cement grouts,their action tends to guard against segregation.

9.2.2 Grout Pumps

A pump suitable for grouting should permitclose control of pressures, allow a flexible rateof injection, and be designed to minimize clog­ling of valves and ports. Orout. pumps are ofthree types namely, piston, screw and centrifugal.

9.3 GroutlDI System ArruaemeDts9.3.1 Manifold or Header

A grout manifold is a 'T" arrangement of pipean~ various fittings, such as couplings, nipples.unions, tees, valves and a pressure gauge, allattached to the collar of the grout hole.

The functions of the manifold are given below:

a) Permlt regulation of the flow of groutinto the hole; ,

b) Maintain the desired allowable groutpressure;

c) Allow any excess grout to be drainedfrom the system or returned to theagitator tank for recirculation; and

7

IS "": 19H

d) Close off the hole when wasbing thesupply lines.

Manifold designs vary and depend on -the typeof grouting system.

9.3.2 Single Line SYItem

The single line system consists of one groutsupply line Crom the pump to the grouting mani­fold at the hole.9.3.~ The pressure gauge should be constantlymonitored so that the pressure on the grout isregulated as long as grouting is in progress. Anydesired increase or decrease in the groutingpressure is obtained by changing the speed ofthe grout pump. When the afout in the supplyline becomes, sluggish, the grout bole valveshould be closed and the blow-off valve openedso that the supply line can be flushed or washed.The grout hole valve should also be checked toensure against a false refusal, Joints in hosesand pipes should be ti.ht. '

9.3.4 Circulation SystemThe circulation system requires two pipe lines,a supply line from the grout pump to the grouthole and a return line from the grout bole tothe agitator/pump. By opening the supply andgrout hole valves, grout is forced into the holeas required. Pressure is maintained by adjustingeither the supply valve or the return va1;'e, orboth, so that complete control of pressure ismaintained at the hole. There should be apressure aauge at the delivery end of the pump.No grout is wasted when washing out the groutI~nes a!1d cl<!se control of the. aroutinl opera­tions II maintained. When direct electric ordiesel drive pumps are employed, use of a returnIine, is necessary. Long supply lines should beavoi~ecl to reduce the chances of change inconsistency of the grout and clogging. Fjeldtelephones are useful for communication be.tween the pump operator and -the grout man atthe collar,

10 WASHING AND TESTING OF HOLESSURFACE PREPARATION '

10.1 The purpose of washing is two-fold. Firstto clean the holes to remove material depositedon the surface during the drilling operation andsecond to provoke deliberate inter-connectionsbetween adjoining grout holes to remove knownseams and layers of erodable material. It shouldbe borne in mind that. inter-connections betweenholes are efB:ective only if the washing opera­tions are carried out systematically to removeaU the soft material. Isolated inter-connectionsdo D~t scrv:e much useful purpose as softmaterials may still remain in position in an!1nknown and irregular pattern. A distinctionIS therefore made between washing of holes atthe end of the drilling operation ( se« 10.2 )

IS "" : 1"4

and systematic washina of groups of boles inorder to remove the erodable material in theintervening area Cor which the term jetting isused (see 10.4 ).

10.2 WublDI of Holes

10.1.1. On completion of the drilling of a stageand before injection, the holes should be washedby allowing the drilling water to run until thereturn from the hole is reasonably clean. Thequantity of water ftowio, into the hole duringthe period should be adequate and generally notless than 15 l/min. c

10.2.1 When no return of drilling or washingwater occurs, the holes should be washed for areasonable period based on site experience. Thisis generally for 20 minutes. If an abrupt loss ofdrill water occurs duriD. drilling and similarlywhen a strong Bow of artesian water is en­countered, the drilliDg should be stopped andthe hole grouted even if it has not reached itsfinal depth.

10.2.3 Should inadvertent connections to ad­jacent holes take place, the washing out shouldbe continued until the flow of water from thehole to which the connection was made isclear.

10.2.4 Where deliberate attempts to obtainconnections between adjacent holes is requiredin order to remove known deposits of erodablematerials, the jetting procedures describedin 10.4 should be used instead of the washingprocedures described in 10.2.

10.3 Percolation Tests

10.3.1 For routine grouting operations, andsimple water test conducted before and afterafoutiug, the test pressure should be limited soas to avoid hydraulic fracture. The value ofIimitina pressure for various strata and depthsshould be established by preliminary investiga­tions where cyclic tests should be conducted toevaluate pressure at which fracturing occurs.Additional tests may be carried out in trialgrouting plots or in selected primary groutingholes to verify tbe pressure limits establishedduring preliminary investigations.

10.3.2 Water percolation tests [ lee IS 5529( Part 2) : 1985] may be used to measure theeffiectiveness of the groutlng treatment. Thetests may be simple or cyclic. Cyclic testing isrecommended for the investigation stage whilebefore and during" grounng operations simpletests should be carried out.

10.3.3 Water tests should be carried out inprimary stales before injection to amplifyinformation available from the site investigation.Test should be carried out in secondary stases

before injection to indicate the results ofprimary Injections. Tests may be carried out inIndividual test holes at any time to indicate theresults of all treatment carried out before thattime. Test holes drilled for this p~se shouldbe sited midway between completed injectionholes'. .

10.3.4 Percolation tests carried out in any stagebefore injection also serve to indicate whetherinjection of that stage can be omitted. Theyalso give some guidance as to the initial groutmix. The actual criteria to be used should bedetermined in the light of site experience.

lO.3.S Observations during grouting of thinmixes are not substitutes for water testing andshould not be accepted in lieu of watertesting.

10.4 JettlDI

10.4.1 Jetting operations are carried out in orderto deliberately provoke connections betweenboreholes and to remove known deposits ofarodable materials.

10.4.2 Jetting should be carried out on groupsof holes arranged in a square, triangular orhexagonal pattern known as cells.

10.4.3 Experience has indicated that the holespacing within each cell should not exceedabout 1·5 m for successful jetting. The optimumspacing at any site can be arrived at by washingholes in a pattern or primary and secondarycells.

10.4.4 All holes in a cell should be fitted withstand-pipes, and then drilled to the level of thefirst seam to be treated. Where a network ofseams exists, all holes should be drilled to theshort first stage depth of 3 m to 6 m. Thestand-pipes should then be capped with three­way plugcocks and the cell is then ready forjetting.

10.4.5 A manifold should be fitted to the firsthole, so arranged that compressed air andwater at high pressure can be fed to the holein rapid alternation. Air and water pressuresused in jetting any stage should not exceed thegrouting pressures specified for that stage.Uplift meters with anchor rods set well belowthe zone being treated may be installed forobserving any upheaval.

10.4.6 All other cocks in the cell should then beopened and water followed by air applied alter­nately . until a connection is made. Jettingshould continue on this connection until DOfurther erodable matter can be removed. Shouldany other hole connect to the manifolded holeduring the operation, its cock should be closed.

8

10.4.7 When the first connection has beencleaned out, the cock on the connected boleshould be closed and the process repeated untilconnections have been established, if possible,to all holes in the cell from the original hole.

10.4.8 The followina alternative procedure mayalso be used for washing the 'cells'.

In washing a cell water is connected to one holeand air to the adjacent bole, on each side. Thewater and air connections are changed at fre­quent intervals to cause the water to tlow inevery possible direction through the seam.Application of air and water pressure is continu­ed until all possible inter-connections betweenadjacent holes are established.

10.4.9 As many combinations of holes as neces­sary, are used to ensure the cleaning of allscams. The washing of any set of boles is conti­nued until all loose materials are removed fromthe seams and crevices. It is neither desirablenor practicable to 'continue washing until thediscoloration in the effluent disappears comple­tely, but it is continued till reasonably clearwater emerges from the holes. Washing is donegenerally for a minimum period of 20 minutesfor each hole. In some zones, washingoperations may have to be extended for severalhours.

10.S Surrace Treatment

10.5.1 For effective treatment of the surfacezones, sufficient pressure should be developed toachieve the spread required with a convenientspacing of holes. Adequate cover should bemaintained during grouting to ensure that ade­quate pressure is applied without causing up­heaval or excessive surface leakage. The follow­ing alternative methods may be used:

a) When the top material is a weak rockwhich can be removed without blasting,one stage of 3 m may be. grouted at lowpressure using top packer in the casing.The casing should be sealed by cementmortar. The grouting of the top stage isconsidered only as 3 capping operationand lh~ rock in this zone should beremoved after completion of the groutingoperations.

b) Alternatively, a cap of concrete about1 m deep should be placed and groutholes should commence through the cap.Explosives should not be used for exca­vation of 1 m rock zone for forming thecap. It should be noted that rock boltingis not an effective replacement for thecap.

e) When the rock is heavily jointed with closespa~ing of joints, the excavation should

9

18"": 1994

be carried out up to the stipulated grade.Thereafter the surface should be coveredby slush grout/gunite consisting of a thickcement sand mixture. After the slush,grouting backfill of earth or concreteshould be placed. A cover of 4 m to 6 mof earthfill may be required to providesufficient weight to counteract groutingpressures. For concrete/masonry dams, itmay be necessary to grout through agallery to ensure adequate depth ofconcrete cover.

10.5.1 It may be difficult to excavate withoutblasting in order to enable methods (a) or (b) tobe used. It may generally be more convenientin concrete dams to conduct shallow lowpressure blanket grouting of the surfacial zones.which may be somewhat disturbed by blasting,after covering the surface with slush grouting.It would then be obligatory to use the galleryfor effective treatment of the main groutcurtain.

11 INJECTION11.1 Holes should be injected by direct connec­tion to the pump. Each hole should be providedwith a packer at the surface or with a shortstand pipe threaded at its outer end to acceptstand or control fittings, which should be provi­ded with a pressure gauge, bleeder valve and avalve enabling the delivery from pump to becut-off from the hole. Either single line or cir­culating system as described under 9.3.2, 9.3.3and 9.3.4 may be used, usually the circulatingsystem is preferred, however, when adequatecontrols are possible to regulate the pump dis­charge and pressure by using pumps of suitabledesign, single line grouting system can be used.11.~ Once the grouting of a stage or group ofholes has been commenced. it should be continu­ed without interruption up to completion. Ingeneral a stage may be considered completewhen the absorption of grout at the desiredlimiting pressure is less than 2 J/min averagedover a .period of 10 minutes.11.3 Ai far as practical, a continuous flow ofgrout should be maintained at the desiredpressure and the grouting equipment should beoperated to ensure continuous and efficientperformance throughout the grouting operation.The personnel-in-charge of grouting as well asthe grouting equipment in use, should respondquickly and effectively to manipulate the desiredchanges in the grout mix consistency, rate andpressure of injections, etc, as directed by theengineer-in-charge during the grouting operation.11.4 Should it be necessary to interrupt injec­tion before it is completed, for instance If thereis a plant breakdown, about 500 1to 1000 I ofclean water should be run into the hole andallowed to stand.

IS 6066: 19M

If any stage continues to absorb large quantitiesof the thickest pumpable grout at nil pressure,grouting may be stopped when a predeterminedlimit of consumption is reached. Alternatively,sometimes it is possible to suspend injectionovernight and resume the work next day. Eventhen the limit of consumption should apply.When any of the procedures recommended isadopted, the grouting operation should beeontroJled as given in 12.

11.5 Should any hole connect to another duringinjection, the grout should be allowed to escapefrom the coupled hole until it is of the sameconsistency as that being injected; the coupledhole should then be capped and the combinedboles brought up to pressure. After the firsthole has been grouted, all the other holes arcsuccessively connected to the grouting headerto subject them to full pressure.Where leakages of grout occur on the groundsurface, they should be restricted by caulkinswith wooden wedges, lead wool, etc, or bythickening the grout followed by retreatmentwith thinner grouts and through fresh holes, ifnecessary.

11.6 Grouting should be stopped wheneverpressure gauges register a sudden drop of pres­sure or the rate of grout absorption increasesabruptly or there is any indication of upheaval.disturbance or leakage. Additional holes mayhave to be drilled and grouted in the vicinityfor sealing fine cracks which may not be effectl­vely treated due to premature blocking of holesby interruption of grouting operations.

11.7 The control of grout mixtures is notamenable to rules which can be fixed in advanceand sufBcient discretion should be left to thefield personnel. Grouting normally starts with athin mixture which is gradually thickened untilabout 75 percent of the final desired pressurehas been obtained with the pumps operating atnorma) speed. As the bole approaches refusal,the thick grout is replaced with thinner P groutwhich is used until the bole refuses. In 12, theguiding principles for controlling pressures andselecting grout mix proportions are discussed.As a general principle grout mixture should notbe thickened if pressure starts to rise after con­tinuous injection over a period of 10 minutes.Hasty changes in mix proportions are not desir­able and the response of the hole to the selectedmix proportions or pressure should be judgedonly after observinr for a sufficient period. Thechoice of the initia mix proportions should bebased on the water intake tests. There are nogeneral rules on the basis of which the initialmix proportions can be decided directly interms of the percolation test results. Bxperi.mentation, at the 'start of the work, should beused to establish the guidelines for choice ofmix proportions, Use of excessively thin mixes

10

in the initial stages is generally wasteful andmay sometimes cause softening of rocks, likeshale. Therefore, a startiDS mix of S : 1 i.recommended and in exceptional cases 10: 1may be adopted.

11.7.1 The ratio of water to solids, of the aroutdeposited finally tn-situ, is generally quite diffe­rent from the water content of the mixed sroutduring injection. The excess water from theafout is removed during the grouting process byfiltration except in exceptional circumstances,as well as when the grout contains admixtures(" such as clay) resulting in formation of stablesuspensions, the grout properties should betested at the water-solid ratios used for themixed grout, in order to verify the suitability ofthe grout vis-a-vis the criteria mentioned in 8.'.For neat cement grouts. with uon-echesiveadmixtures, it is leDerally found that the setgrouts are very much denser than groutspecimens prepared in the laboratory from themixed grout; hence due allowance should bemade for the removal of water tn-sit» whileinterpretins the laboratory test data.

11.8 After grouting is completed, the scoutholes should be closed by means of a valve tomaintain the grout pressure for a sufficientperiod to prevent escape of the grout due toback pressure and flow reversal, due to causeslike artesian conditions. For this purpose aperiod of one to two hours is generally suffici­ent, however, this should be verified by trial.

12 CONTROL OF GROUTING OPERATION

12.1 Preaure

The pressure should be adequate to achieve thedesired grout and the pressure should be limitedso as to avoid disturbance and upheaval of theground and should take into account reservoirpressure.

12.1.1 For structures on rock foundations, it isa basic requirement that no disturbance shouldbe caused to the surface zones of the founda­tion by the grouting operation. When groutingis undertaken below an existing structure noupheaval of the foundation can be allowed as itwould have very harmful consequences on thestructure and/or equipment.

12.1.2 In general, the disturbance caused bygrouting is dependent more on the manner inwhich the pressure is developed and the natureof the rock than on the absolute magnitude ofpressure. Relatively hiaher pressures can besustained without damage to the foundations,when pressure is built up gradually, as resis­tance to flow is developed by deposition ofgrout. On the other hand, when pressures areraised hastily, damage could occur .even atrelatively low pressures. In general, horizontal

stratified or low dipping rocks are more vulner­able to disturbance by grouting pressure thanfractured igneous or metamorpbic rocks orsteeply dipped sedimentary rocks. Rockspreviously subjected to folding and fracturing orrocks in the process of adjustment after removalof overburden load are also more vulnerable todisturbance.

12.1.3 It is always advisable to begin with alow initial pressure say 0'10 to 0'25 kg/cm'/mof overburden, and build-up the pressuregradually. Initially the rate of intake may be20 J(min to 30 l/min. In order to avoid thepremature build-up of high pressure a generalguideline should be followed that the pressureshould be raised only when the intake rate fallsbelow S l/min. When surface leaks develop,pressure should be immediately reduced. Sub­surface cracking may sometimes be indicatedby an abrupt rise in the rate of intake aftergrouting at a constant value of pressure for aconsiderable period•.

12.1.3.1 The most common difficulty experienc­ed in consolidation grouting is surface leakage.It is therefore customary to pipe through therequired height of concrete or masonry and carryout the grouting after the rock has been com­pletely covered. This not only eliminates surfaceleakage but permits use of higher pressures sothat even the smaller seams can be groutedeffectively.

12.1.3.1 The true pressure at any depth shouldtake into account the pressure head caused bythe weight of the grout in the hole, niscorrection in kg/em' may be computed bymultiplying the depth of the bole in metres byfactors relative to the water-cement ratio givenin Table 2 and added to the pressure gaugereading at the top. of the grout hole.

Table 2 MaltlplyID.; F.ctors

Water-Cem.Dt I'-aor Water-C••eat Paetoraatlo Ratio0'75 0-1'1 2-50 0-J181-00 0-140 2-75 0"1171"25 0'131 3"00 0"112I'SO 0'127 4'00 0-1101'75 0'123 5'00 0-1072-00 0'121 10'00 0'1022-25 0-119

12~1.4 Control of pressure should be exercisedaccording to the following guidelines:

a) The limiting value of pressure for eachzone and depth may be established initi­ally from the results of trial gfoutinl.

along with observations of upheaval byuplift puge. Figure 2 may be used as aguide, subject to verification by trialgrouting;

b) Pressure limits may be decided by analy­sis of the results of cyclic percolationtest; and

c) Limiting pressures may be decided bycontinuous review of the trends ofpressure and rate of intake duringgrouting operations.

12.1.4.1 Limiting values of pressure for tachzone may be established initially on the basis ofthe categorization of rock as suggested in Fig. 2should be taken as initial values to be confirmedby trial and observations. The choice ofpressure may also be established by examiningwater test data.

12.1.4.2 The pressure limits initially establishedas per 12.1.4.1 should be further reviewed byexamiDing trends of grout intake and pressuresduring initial stages of actual grouting opera­tions, The method of interpretation of trends ofgrouting pressure is described in Annex B. Itshould be recognized that the resistance to Bowof grout pressures is built up gradually. Conse­quently higher pressures may be used in watertests without causing hydraulic fractwina.Normally, the aim should be to obtain 'A' typetrends. This trend signifies increase of rests­taace of flow as the jointa/cracks/cleava•• arefilled by the grout. 'S' type trends can bepermitted since they imply a ftuctuatiog res­ponse. Grouting with 'B' type trend may becontinued till the limit of consumption is attain­ed or refusal may be attained eventuallyby restrictiul the pressures or by thickening thegrout when 'B' trends develop. 'B' trends thusconstitute a permissible deviation from theideal which should be minimized by carefulcontrol. When pressure limits are properlychosen 'A' type trends would predominate.Under/.DC! circu~stanccs -c type trends shouldbe _pe~ltted since they imply hydraulic frac­turiDS. The pressure control criteria initiallychosen as per 12.1.4 should be modified on thebasis of the analysis of the trends of arout iD8pressures and intake. The chosen pressure limitsonaure that 'At treDda are .enerally achievedand 'e' trend. are eliminated.

~2.1.5 Slt~atioDS arise ill practice when hydrau­lIC fracturtnl may occur before uplift is observ­ed or surface 1ealcale is noticed. This is attri­but~ble . to developm~nts o~ localized highstr~lns In rock associated wlth hydraulic frac­turin,. Upheaval may be noticed only whensutBclent volume of grout is injected into thefract~ed zones to cause dispJacements in thesurfaclal zones.

II

SOUND STRATIFIED ROCK IROUTEDAIOVE 6IYIN ELEVATION

IS 6066: U94

45

40

~

i 35

~30

'"--- -

~ 25:;)en

! 20...~ 151&1•t 10

! I

0.7 1-75 3-5 S·25 7 10·5 14 21 21 35

APPROXIMATE PRESSURE IN kg/Cm2 AT GIVEN DEPTH

FIG. 2 GUJDB POR GROUTING PRESSURBS

42

Observations of pressure trends provide a moredefinite indication of hydraulic fracturing andtherefore greater reliance should be placed oninterpretations of trends of pressures and groutintakes, rather than upheaval measurements.

12.1 Grout mixture ( ratios by weight of waterand cement) ranging from 5: 1 to 0·8 : 1 arerecommended. It is only in exceptional circum­stances that mixtures leaner than 10 : 1 need beused. The choice oC grout mixtures may bebased on results of percolation tests conducted.prior to grouting ( see 12.1.4). The ideal wouldbe to conduct a percolation test in each hole.for each stage. However, the number of perco­lation tests may be reduced if extent of zones ofdifferent types of rock and rock characteristicscan be established on the basis of geologicalevidence and results of initial experimentalgrouting operations. It is inadvisable to relaxthe requirements of percolation testing in theinitial stages of grouting and grout absorptionsat low water-cement ratios are a poor substitutefor water percolation tests.

12.1.1 If grout is too thick, passages of grouttravel may get obstructed at a short distanceand fine seams may not be filled up. On theother hand if injection with thin grout is conti­nued for too long a time, the grouting opera­tion may get unduly prolonged and may berendered unduly expensive. If openings arelarle and grout is thin, grout consumption willbe excessive even with low pressure. In the caseof fine cracks additions of bentonite, say 2 to3 percent in a grout mix, will have lubricatingaction. No general rules can be stipulated

12

regarding the manner in which the thickeningof the grout is to be carried out. The appro­priate sequence for every site may be decidedafter a review of the results of initial grouting.A judgement about the efficacy of a particularsequence may be had by comparing the .routconsumptions of the primary and secondary orsecondary and tertiary holes. As a guide, themix should be thickened if there is DO increasein the pressure after continuous grouting ofabout 10 min.

12.2.2 When multiple line grout curtains areused, the control oC grouting operation woulddiffer from single line curtains. In the outerlines thick grouts may be used to prevent over­travel and to block the more pervious zones. Inthe inner or central lines, grouts may be thick­ened very gradually and comparatively thinnergrout may be used at the start. Similarly thethickening of grouts may be carried out moregradually in tertiary holes as compared toprimary and secondary holes. In order toprevent overtravel of grout in the case of widejoints, sodium silicate or sodium hen metaphosphate is sometimes added, while for in­creasing the ftowability in the case of thin joints,2 percent to 3 percent bentonite is added.

1%.2.3 The thinning of the grout may be helpfulin preventing abrupt rise in pressure and/orclogging of the equipment at the end of thegrouting operation. Thinning of the grout is notpermissible when stable grout suspensions areused that do not allow exclusion of the excesswater by filtration. If such grouts are diluted,the strength and imperviousness may be

compromised. Alternatively it is recommended tokeep more than one grout design ready with theuse of clay-cement, bentonite-cement, bentonite­chemical, etc, so that these mixes can be usedwithout change of mix design.

12.2.3.1 A recommended method is also toarrange for grout refusal to occur while a thinmix is being pumped, even though 3: 1 to 1 : 1mixes were used temporarily.

12.2.3.2 With packer grouting and thin beginn­ing mixes, the section of hole just completed isautomatically exposed to the new beginningmix. This of course does not apply to the last ortop section of the hole. In special cases, such asa large opening into which a lot of grout hasbeen pumped or in a zone in which refusal wasspecially difficult to obtain or again in the caseof a deep interconnection this process mightnot be performed and thin mixes may be omittedfor 6 m or so, overlying the troublesome zone,or the section might be allowed to rest for afew hours before higher sections are treated.

1%.3 CODtrol of Grout CODsumption

When pressure does Dot build up even aftergroutiDI a thick grout, that is, grout with watercement ratio lesser than 0·6: 1 by weight orricher, or by grout. with fillers, such as clay,sand and bentonite. it is desirable to stopgrouting after the predetermined limit of con­sumption is reached. The choice of the limit ofconsumption will 'depend on the leDlth oC astage and the size of the cavities, open jointsaud fissures. After grouting a hole, In whichgrouting has to be stopped because the con­sumption limit was reached, it is necessary todrill additional holes in the vicinity and groutthem with more fluid grouts in order to penet­rate the finer cracks and joints which may nothave been grouted in the initial operation. Insuch situations a: multiple line curtain may beused with advantage and the sequence ofgrouting should be as given in 12.1.2. Guidanceregarding method of recording the details ofgrouting operation and determining the qualityof grout consumed are described in Annex C.

12.4 Back FlIllDI 01Grout Holes

Grout holes are backfilled with grout having awater-cement ratio of 0'7 : 1 with 3 percent ofbentonite. A delivery pipe of minimum 2S mmdiameter is lowered to the bottom of the hole.Grout is pumped in the delivery pipe until itflows from the hole, then the delivery line isslowly withdrawn while pumping continues. Ifsettlement of grout occurs after initial set, theholes are alain back filled with grout.

IS

1S'lOUj 1994

13 TESTING THE EFFICACY OF GROUTINGOPERATION

13.1 The efficacy of the grouting operation maybe estimated using one of the followingmethods:

a) Pre and post grouting permeability valuesusing percolation tests.

b) Pre and post grouting P-wave velocitiesusing seismic refraction/cross holegeophysical techniques and changes inmass using gravity methods.

c) Pre and post grouting deformationmodule using static methods.

d) Pre and post measurement of pore waterpressure.

14 RECORDS

14.1 The information to be recorded daily is asfollows:

1) Result of the pressure test;

2) Grouting feature, for example, curtainand consolidation;

3) Date;

4) Shift;

S) Name of foreman;

6) Grouting method, packer grouting or full­depth grouting and stage whether first,second or third;

7) Hole station Dumber or co-ordinates;

8) Time grouting begun;

9) Time of each change in mix, pressure, orpumping rate;

10) Name of inspector;

11) Time of hole completion;

12) Total quantity of cement used for eachpressure or mix change;

13) Water-cement ratio at the start and eachchange thereafter;

14) ~ir pressure;

15) Grout consumption and time required forconsumption of each batch;

16) Pressure recorded at 3 min to 15 minintervals and on completion;

17) Rate of injection;

18) Cement washed;

19) Total quantity of cement injected into thehole;

IS "": ItN

20) Reason for abandoned holes;

21) Number and depth of holes left forredrilling; and

22) In addition, the inspector should recordunder cRemarks' any change or incidentaffecting the grouting operation; such as'tight hole', 'no leakage', 'had leakage','leaks caulked', 'grout pump down', 'holecompleted', and so forth.

14.1 Reports

In order to facilitate control and planning ofgrouting operations, reports should be preparedat regular intervals to summarize importantobservations and data. It serves no useful pur-

pose to maintain elaborate records unless theycan be compiled in such a form that significanttrends can be determined regarding the efBcacvor otherwise of the greuting operations. In theabsence of such reports timely action would notbe possible and procedures which may beIneffective or unsuitable may be continuedindefinitely. These reports may consist of:

a) a hole-wise register of drilling, watertests, grouting and interconnecnons,

b) for consolidation grouting - a planshowing grout hole stages and groutintake.

c) for curtain grouting - a eL' sectionshowing drilling stages and grout' intake.

ANNEX A( Clause 2 )

LIST OF INDIAN STANDARDS

calcined( second

IS No.

269 : 1989

383 : 1970

455 : 1989

1344 : 1981

1489(Part I ) : 1991

1489( Part 2 ) : 1991

Title

Specification for 33 gradeordinary Portland cement(fourth revision )

Specification for coarse andfine aggregates from naturalsources for concrete (secondrevision)

Specification for Portlandslag cemen t ( fourthrevision)

Specification forclay pozzolanarevision )

Specification for Portlandpozzotana cement: Part Ifly ash based ( thirdrevision)

Specification for Portlandpozzolana cement: Part 2Calcined clay based ( thirdrevision)

IS No.

3812 : 1981

5313 : 1980

5529( Part 2 ) : 1985

6909 : 1990

8112 : 1989

9103 : 1979

12269: 1987

12330 : 1988

12584 : 1989

14

Title

Specification for fly ashfor use as pozzolana andadmixture (first revtslon )

Guide for core drillingobservations (first revision)Code of practice for in-situpermeability test: Part 2Test in bedrock (firstre,ia/on)Specification for supersul­phated cementSpecification for 43 gradeordinary Portland cement(first revision)

Specification for admixturesfor concreteSpcification for 53 gradeordinary Portland cementSpecification for sulphateresi!\ting Portland cementSpecification for bentonitefor grouting in civil engi­neering works

IS"": I"

ANNEX B( Clause 12.1.4.2 )

METHOD OF INTERPRETATION OF TRENDS OF GROUTING

B-1 The categorization should be done as follows by computing the ratio of rate of grout intakeand gfouting pressure and examining the trend of variation as the grouting operation continues:

a) Ratio of Rate or grout intake D · 'A' t dGrouting pressure ecreasing : ren

b) Ratio of Rate of.grout intake Constant : 'B' trendGrouting pressure

R· f Rate of grout intake r · 'e' t dc) atlo 0 Grouting pressure ncreasmg : ren

ANNEX C( Clause 12.3 )

C-l For measurement of the quantity of groutinjected in each hole, a grout history sheet onproforma given on next page should 'be recordedaiving grout in-take per minute, viscosity ofgrout mix in form of solids and water ratio,pressure of injection, time of pumping in waterfor lubrication event of blowing grout to keepthe grouting system alive. In addition, variousother points of im~ortance observed during theoperation of grouting are recorded for every5 min to 10 min intervals and thus the goutflistory sheet when plotted as shown in Fig. 3should depict the exact amount of groutinjected. Actually this graph from the grouthistory sheet should be plotted to depict thefactual amount of grout injected. The area underthe curve would represent the quantity of groutactually injected. A register should be maintainedof 100 such sheets. Each sheet should be machinenumbered on both sides.

C-2 Recording of the surface leakage, jf any,should be made in the remarks column of thegrout history sheet sbowing the location. Theleakage should be immediately stopped byreducing the pressure and caulking suitably. The

grout should not be allowed to leak more than"5 percent by visual judgement.

C-3 Measurement of cement, blown off andcirculated in the grout lines, should be separa­tely recorded in mass of the cement used forpurposes of accounting the cement actually usedfor the work.

C~ In case of stale grouting of the hole,cement grouted in each stage should be summedup.

e..! Many of the holes often require regroutingand this should be recorded In linear metreseparately.

C-' For work of grouting for anchors (plainor cylindrical) stubbed with under-reaming,the quantity of grout should be in mass ofcement. Aluminium powder should be accordingto quantity actually used. The length of holesand anchor bars should be referred in linearmetres. For under-reaming for stubbed anchor,the unit for bulbs should be in numbers forrecord of the under-reaming done with sectionof bulb provided.

15

IS 6066 : 1994

,20

GROUT INTAKE VITIME PLOT

P V. TIME PLOT

--~r-e... .....~-.--"3-----........

25' 30' 3S 'o' 45' 50' 55' 1h 5'

TIME IN MINUTES/HOURS

o

3

100

300

400 400

ee....' 300zUJ~UJ...J...~ 200 N ~OO e 2~--n1--""""'---fn E ::~ ~ ac~~ 1000­J

NOTE - Area under the curve tgrout intake Vs Time' also includes the amount of grout blown off in casearout intake Vs Time plot accounts for blowing off.

Ill, "I. II. c= Water: Solid ratioP - PressureQ - Grout intake

FIG. 3 GRAPH PROM GROUT HISTORY SHEET

Typical Proforma of Grout History Sbeet( CllllUe e-l )

FeatureQIId RD01Ho/~

HoleNo.

DepthDrilled

Method Pressure Groutj---••-""-._--~ Consis-Specified Used tenc»

Time Rate Remarks01 About Type

Consump- 0111011 Leak~,

16

Bureau of IndlaDStandards

BIS is a statutory institution established under the Bureau of Indian'Slandar'" Act, 1986 to promoteharmonious development of the activities. of standardization, markin.g and quality certification of goodsand attendingto connected matters in the cOUntry.

Copyright

BIS has the copyright of all its publications. No part of these publications may be reproduced in any formwithout the prior permission in writing of BIS. This does not preclude the free use, in the course ofimplementing the standard, of necessary details, such as symbols and sizes, type or grade designations.Enquiries relating to copyright be addressed to the Director (Publications), BIS.

Review of Indian Standards\ ~'\

Amendments are issued to standards as the need arises on the basisof comments. Standards are also reviewedperiodically; a standard along with amendments isreaffirmed when such review indicates that no changes areneeded; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standardsshould ascertain that they are in possessionof the latest amendments or edition by referring to the latest issue of'BIS Catalogue' and 'Standards: MonthlyAdditions'.

This Indian Standard has been developed from Doc : No. RVD8 ( 98 ).

Amendments Issued Since PublicatloD

Amend No. Date of Issue

BUREAU OF INDIANStANDARDS

Text Affected

Headquarters :

ManakBhavan,9 BahadurShahZafar Marg, New Delhi,110 002Telephones: 2323 01 31,2323 33 75,2323 9402

Telegrams : Manaksanstha(Commonto all offices)

RegionalOffices :

Central : Manak Bhavan,9 BahadurShah Zafar MargNEW DELHI 110002

: C.I.T. Campus, IV Cross Road~ CHENNAI600 113

: 1/14 C.I.T. SchemeVII M, V. I. P. Road, KankurgachiKOLKATA 700 054

: seo 335-336,Sector34-A,CHANDIGARH 160022

Eastern

Northern

Southern

Western

Branches:

Telephone

{2323 76 172323 3841

{2337 84 99, 2337 85 612337 8626,233791 20

{260 3843260928S

{2254 12 16,2254 14422254 25 19,2254 23 1S

.: Manakalaya, E9 MIDC, M~l, Andheri(East) { 283292 95. 2832 78 58MUMBAI 400 093 28327891,2832" 92

AHMEDABAD. BANGALORE. BHOPAL. BHUBANESHWAR.COlMBATORE.FARIDABAD.GHAZIABAD. GUWAHATI. HYDERABAD. JAIPUR. KANPUR. LUCKNOW. NAGPUR.NALAGARH. PATNA. PUNE. RAJKOT. THIRUVANANTHAPURAM. VISAKHAPATNAM.

Printedat Prabbat0flJet Press.NewDelhi·1