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Indian Standard

GLOSSARYOFTERMSRELATINGTO RIVER

VALLEYPROJECTS

PART 8 DAMS AND DAM SECTIONS

( First Revision)

UDC 627.82 : 001.4

@ BIS 1992

BUREAU OF INDIAN STANDARDS

MANAK BHAVAN, 9 BAHADUR SH AH ZAFAR MARG

NEW DELHI 110002

April 1992 Price Groop 9

( Reaffirmed 1997 )

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Terminology Relating to River Valley Projects Sectional Committee, RVD 2

FOREWORD

This Indian Standard ( Part 8 ) ( First Revision ) was adopted by the Bureau of Indian Standards, afterthe draft finalized by the Terminology Relating to River Valley Projects Sectional Committee had beenapproved by the River Valley Division Council.

A large number of Indian Standards have already been printed covering various aspects of river valleyprojects and some more similar standards are in the process of formulation. These standards includetechnical terms, and precise definitions for these are required for avoiding ambiguity in their interpretation.To achieve this aim, the Terminology Relating to River Valley Projects Sectional Committee is bringingout Indian Standard glossary of terms relating to river valley projects ( IS 4410 ), being published in parts.This Part 8 contains definitions of terms relating to dams and dam sections.

This standard was first published in 1968. The present revision of the standard has been taken up in the

light of experience gained during the last 23 years in the use of this standard. In this revision, additionalterms have been added besides modifying some of the terms so as to bring them in line with latesttechnology.

In the formulation of this standard, due weightage has also been given to international co-odination among

the standards and practices prevailing in different countries. This has been met by deriving considerableassistance from cMultilingual technical dictionary on irrigation and drainage’, published by InternationalCommission on Irrigation and Drainage ( ICID ) and other sources.

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I84310 c-8) tl992

. Indian Standard

GLOSSARY OF TERMS RELATING TO RIVERVALLEY PROJECTS

PART 8 DAMS_ AND DAM SECTIONS

( First Rev ision )

1 SCOPE

1.1 This standard contains definitions of termsrelating to types of dams, dam sections, galleries,shafts and tunnels, joints and grouting in dam.

1.2 It does not contain terms relating to weirs,barrages and spillways.

2 TYP ES OF DAMS

2.1 Arch Dam

A curved solid masonry or concrete dam, convexupstream, that depends principally on arch actionfor its stability. The water load is mostly trans-ferred by the arch to the canyon walls, ‘or otherabutments. It is also called ‘Arched Dam’.

2.2 Ar c h G r a v i t y D a m

A curved solid masonry dam which depends uponboth arch action and gravity action for stability.Also called ‘Curved Gravity Dam’. Arch gravity

dam has the base thickness between O-5 to 0.6times the height of dam.

2.3 Articulated Type B u t t r e s s D a m

Same as simply supported flat slab deck dam.

2.4 Bag Dam

A low dam made of bags partly filled with soilor boulder concrete. Bags are partly filled to per-mit flexibility in placement,

2.5 Basket Da m

A dam composed of boulders held in woven wirecrates and piled up to form a barrier.

2.6 Beaver Type Dam

A fixed timber dam used for low heads, the bentsbeing of round timbers or logs with butts pointingdownstream, spacing logs laid transversely, crevi-ces filled with gravel, covered with a plank deck,the whole structure being fastened together withdrift bolts, and to the foundation with anchorbolts. It is seldom used as a permanent structure.

2.7 Boule Dam

A movable dam similar to a Poiree Dam( see 2.67 ) but with horizontal stop logs or panels,

instead of needles which span from trestle totrestle.

2.8 B r u s h D a m

A check dam made of brush wood usually heldin place with stakes and wire.

2.9 Bulk Head Rutt;ess Dam

A type of buttress dam ( see 2.10 ) in which theface slab is replaced by flaring the upstream edgeof the buttresses to span the distance betweenbuttress walls. The flaring portion may be ofvarious geometrical shapes, namely, (a) massivehead; (b) round head or mushroom head; and(c) diamond head. The buttress dams comprisingtypes of head classified above are named .accord-ingly. It is also calIed ‘Round Head ButtressDam’.

2 .10 But t re s s Dam

A dam consisting of a water supporting upstream

face or deck, usually reinforced concrete slab,supported by buttresses generally in the form ofequally spaced triangular reinforced concrete ormasonry walls or counterforts, that transmit thewater load and weight of the deck to thefoundation.

2.11 C a n t i l e v e r B u t t r e s s D a m

A flat deck dam where the slab is cantileveredfrom the buttresses.

2.12 Cantilevered Steel Dam

See 2.87.

2.13 Check Dam

A small low fixed dam, constructed of brush, logs,timber, loose rock, masonry, or concrete, in aneroded channel to reduce the slope of the waterflowing therein during high stages, and also theresulting velocity, thereby preventing excessivescour and erosion and inducing deposition. Areduction in the size of flood peaks of erosion, andsometimes an increase in low-water flow due toincreased ground storage often result from build-ing a check dam. Such dams are also used toretain debris. They usually are built of inexpensiveand temporary materials where dependence forultimate protection is placed on vegetative cover.

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IS 4410 ( P u t 8 )

2.14 Coffer Dam

i 1992

It is a temporary structure to exclude water or

water and earth from a specific area to facili tateconstruction.

2.15 C o l u m n e r B u t t r e s s D a m

A type of deck dam in which the massive buttres-

ses are replaced by a series of inclined columns.

2.16 Composite Da m

A concrete/masonry wall with rockfill or earth-backing in downstream.

2.17 Composite Earth Dam

An earth dam consisting essentially of an inner orenclosed impervious section supported by two ormore outer sections of relatively pervious material.It is also called ‘Multiple Zoned Earth Dam’ or

‘Zoned Earth Dam’.2.18 C ono i da l D am

It is a modification of cupola arch buttress damand has some of the characteristics of the hol lowgravity dam and some of those of multiple archdam. The upstream face is a plane slightly in-clined to the vertical; the downstream face is aconoidal surface generated by straight lines, whichwhere they touch the horizontal at the crest areorthogonal there-to and repose on a directrixdrawn in a horizontal plane ( see Fig. 1 ).

FIG. 1 CONOIDAL DAM

2.19 Cons ta n t Ang le Arch Dam

It is a special type of variable centre dam inwhich the central angle of the arches are ofapproximately the same magnitude at all elevation( see Fig. 2 ).

2.20 C o n s t a n t C e n t r e Ar c h D a m o r

C on s t a n t R a d i u s Ar c h Da m

A type of arch dam whose arch centres for theupstream face and the downstream face are coin-

cident with the axis centre at all elevation. Aprofile of these centres is a vertical straightlineand the arches are of uniform thickness. All canti-levers are of identical shape, varying only in baseelevation ( see Fig. 3 ).

2 .21 Cons t an t ’ Cen t r e Dam

Se e2.20.

2 .22 Cor e-Wall Type Rock f i ll Dam

A rockfill dam in which a core wall of steel,concrete ( plain or reinforced ) or compactedearth is placed in the centre, and the rockfill is

dumped on both sides.

2.23 Cored Gravity Dam

It resembles hollow gravity dam in principle ex-cept that hollows are provided along contractionjoints and not in the middle of the section ( seeFig. 4 ).

A timber dam consisting of a series of cribs orrectangular cells made of square or round timbers,drift-bolted together, filled with broken rock orboulders, with a upstream facing and deck coveredwith heavy planks to provide watertightness.

2.25 C u p o la Ar c h B u t t r e s s D a m

Here the upstream face of the buttress dam con-sists of semi-cupolas of ovoidal form of reinforcedconcrete. F’urther modification of this dam isconoidal dam.

2.26 Cupola A r c h D a m

Same as double curvature arch dam.

2.24 Cr ibe Dam

2.27 Da m

2.28 D e b r i s D a m

2.29 D e t e n t i o n D a m

2.30 D ir e c t -S t r u t t e d S t e e l D a m

A type of steel dam in which the load is trans-ferred from the deck to the foundation throughinclined struts ( see Fig. 5 ).

2

A barrier constructed across a river or naturalwatercourse for the purpose of : (a) impoundingwater or creating reservoir ( see 2.48 ); (b) divert-ing water there from into a conduit or channelfor power generation and or i rrigation purpose;.(c) creating a head which can be used for genera-tion of power; (d) improving river navigabili ty;(e) retention of debris; (f) flood control;(g) domestic, municipal and induses; (h) preser-vation of wild life and pisciculture, (j). recreation,etc.

A dam buii t across a stream channel to catch andretain debris, such as sand, gravel, silt anddriftwood.

A dam whose principal purpose is to temporarilydetain all or part of the runoff and enable itsrelease at controlled rates, as and when required.

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FIG. 2 CONSTANTANGLB ARCH DAM

FIG. 3 CONSTANTRADIUS ARCH DAM

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A-A

CRETE DIAPHRAGM

WE8 PORTION

SEALS1 \FOUNDATION GALLERY

PLAN

FIG. 4 CORED GRAVITYDAM

FIG . 5 TYPICAL DIRE CT-STRUTTED YPE STBBL_ AM

“2.31 Di ve r s i on Dam 2.32 Dome Dam

A fixed dam built far th e pu rpose of diverting

par t or all of th e water from a str eam out of an d A curved masonry, or concrete

awa y from its cour se. It is also called ‘Diverting strea m th at depends principally

Weir’. for it s-sta bility ( see Fig. 6 ).

4

dam convex up-

on dome action

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2 .40 Fr ee Deck D a m _

A flat deck dam where the slab is freely supportedon the buttress.

FIG. 6 DOME DAM

2 .3 3 D o u b l e Cu r v a t u r e Ar c h D a m

It is an arch dam which is curved in plan and inelevation with under cutting of the heel and inmost .instances, downstream overhang near thecrest. It is also called Cupola Arch Dam’.

2.34 E a r t h D a m

2.41 G ra ve l F i l l D am

It is a dam composed of gravel or shingle withthe downstream part made of relatively coarsematerial, and the upstream or water side partmade of finer gravel and sand.

2.42 G r a v i t y D a m

A solid concrete or masonry dam so designed andshaped that its weight is sufficient to ensure stabi-lity against the effects of all imposed forces ( SeeFig. 9 ).

2.42.1 High Gravity Dam

A gravity dam above 90 m in height is calledhigh gravity dam.

2.42.2 Low Gravity Dam

A gravity dam less than 30 metres in height iscalled low gravity dam.

2.42.3 Medium Height Gravity Dam

A gravity dam between 30 metres and 90 metresin height is called medium height gravity dam.

2.43 H ol low B ase D am

Same as hollow gravity dam, where a big cavityis left only in the bottom portiondam. -

-4 Hol!s_=; Dam

2.35 F a b r i D a m

It is hollow dam of reinforced rubber. The damis inllated and deflated as required by use of airor water.

2.36 F i r e d D e c k D a m

A flat deck dam where the slab is integrally castwith the buttress. Also called ‘Fixed Slab ButtressDam’.

.\

2.37 F i x e d S la b B u t t r e s s D a m

Se e 2.36.

2.36 F l a t S l a b D e c k D a m

This type of dam is made of a flat reinforcedconcrete slab, which transmits water pressure to aseries of parallel buttress which rest directly onthe foundation or upon a concrete slab resting onthe foundation material ( see Fig. 8 ).

2.39 F r a m e d D a m

A low fixed dam generally built of timber framesto form a water face, supported by struts.

A modification of buttress dam in which thebuttresses are grouped or joined together leavinghollow spaces.

2.45 H ol low G rav i ty D am

It is a structural refinement of the solid gravitydam in which some concrete from the low stressareas of solid dam is removed to reduce upliftpressure and a slop is provided to upstream faceof the dam to take advantage of the water loadfor improving stability. The base is also widenedin direction of the thrust to improve stabilityagainst overturning and sl iding ( see Fig. 10 ).

2.46 H o m o ge n e o u s E a r t h D a m

An earth dam composed of a single type of mate-rial, except for protective material on the exposedfaces.

2.47 H y d r a u l i c F i l l D a m

An earth dam, in the construction of which all ormost of the materials have been transported byagency of water to the dam and placed in the damby dredging, sluicing, or pumping. Generally, forgreater imperviousness, the fine material in thesluiced earth is segregated and deposited alongthe centre of the dam to form a core.

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2.48 Impounding Dam

set 2.27.

2.49 L a r g e D a m

A dam above 15 m in heightlowest portion of the generalthe crest or a dam betweenheight, provided it compliesthe following conditions:

a) The length of crest ofless than 500 m;

measured from thefoundation area to10 m and 15 m inwith at least one of

the dam to be not

b) The capacity of reservoir formed by thedam to be not less than 1 million ms;

c) The maximum flood discharge dealt withby the dam to be not less than 2 GO0 ma/set;

CORE

UPSTREAM SHELL

d) The dam had specially difficult foundationproblems;

e) The dam is of unusual design.

2.50 L a n d s l i d e D a m

An obstruction formed in the stream Bow due tonatural causes, like huge rockfalls, landslides, orsnow avalanche from the side slope resulting incomplete or partial blockade.

2.51 Levee

An earthen embankment extending generallyparallel to river channel and designed to protectthe area ,behind it from overflow by flood waters.

2.52 Loose Rock Dam

A dam constructed of variable size rocks, withoutmortar, usually dumped in place without anyparticular effort at packing sorting or arranging.

/-TRANSITION FILTER

UPSTREAM BLANKET DOWNSTREAM SHELL ORDOWNS?REAM FILL

FIG. 7 TYPICAL EARTH DAM

BASE WCKNESS

UPSTREAM ELEVATION CROSS SECTION

FIG. 8 FLAT SLAB DECK DAM

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INSPECTION

GALLERY

DOWNSTREAM

FIG. 9 GRAVITY DAM

FIO. 10 HOLLOW GRAVITYAM

2.53 Lif t ing Dam

A dam of any type of construction meant to raisethe water level for diversion purposes without anyappreciable storage.

2.54 M a s o n r y - c u m - E a r t h D a m

A dam comprising portion of earth and masonry

along its length ( spillway, not included ).

-JOINT

2.55 Mason r y Dam

A dam composed of one or more of the followingmaterial brick or stone masonry.

2.56 M a s si v e H e a d Bu t t r e s s D a m

See2.9.

2 .57 M edium Arch G r av i ty D am

It is an arch dam where the thickness of base isbetween O-2 times to O-3 times the height.

2.58 M od i fi e d H o m o g e n e o u s E a r t h D a m

An earth dam, in which small amounts of pervi-ous material selected to control the action ofseepage are suitably incorporated in an otherwisehomogeneous dam.

2.59 M ul t ip l e Arch R am

A buttress dam composed of a series of inclinedarches supported by buttresses or piers. The loadis transferred from the arches to the foundationthrough the buttresses ( see Fig. 11 ).

2.60 M ul t ip l e D om e B ut t r e s s D am

A buttress dam in which massive buttresses spacedfar apart support a set .or series of domes on whichthe water rests ( see Fig. 12 ). It is also called,‘Multiple Dome Dam’.

2.61 M ul t ip l e D om e D am

See2.60.

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BUTTRESS BRACING

7 BUTTRESS 1

. 2i62

aI BUTTRESSSPACING

III II CROWN

:Rz SPAN

OF ARCH

adEXTRADOS

L INCLINED BARREL

ARCH

-- -_ ------ BUTTRESS

BUTTRESS BRACING? m//

INTRADOS A

SPRINGING LINE\

CROWN OF ARCH

FIG. 11 MULTIPLE ARCH DAM

M u l t ip l e Z o n e d E a r t h D a m 2.66 O vern ow D am

Se e2.17.Se e 2.65.

2 .63 N on& ver F low D am2.67 Po i r ee D am

The dam portion which does not allow to escapeAood waters by overtopping is called non-overflowdam.

2.64 Non-Rigid Dam

A dam constructed with non-rigid materials ormaterials like earth rockfill, etc.

2.65 O ver fa l l D am

A dam constructed with a crest to permit the over-

flow of water. Also called ‘Overflow Dam’ and*Spillway Dam’.

A dam consisting of a curtain of timber needlessupported at the bottom by a sill and at the topby a beam carried by moving steel trestles.

2.68 P o l y -C e n t e r e d o r T h r e e -C e n t e r e d D a m s

These dams are variable centre dams in whichthe location of centres and radii associated withthem also x&y horizontally to produce dams

with elliptically shaped or multicentered archelements.

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increases the initial compressive stress in theupstream portion of the dam allowing for thinnercross section than those for gravity dams. Thepost-tensioning bars or wires are arranged ingroups, and located in holes or shafts, and areanchored into the foundations ( shaft anchorage )( see Fig. 13 ).

2.70 Rig id Bu t t r e s s Dam

A dam having upstream water supporting membersconstructed monolithically with the buttresseswith no provisions for unequal foundation settle-ment or for expansion and contraction betweenadjacent bays. Examples of the rigid type aremultiple arch and continuous deck type ( seeFig. 14 ).

2 .6 9 P r es t r es sed Dam

A dam comprising of concrete which, by post-tensioning with high tensile steel bars or wires,

PLAN

SECTION XXFIG. 12 MULTIPLEDOME DAM FIG. 13 A TYPICALPRESTRBSSEDAM

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fb441O(Pa r t8) :1992

FIG. 14 RIGID BUTTRESS DAM

2.71 Rigid Dam

A dam constructed with rigid material such asmasonry, concrete, steel or timber.

2.72 Rockf i ll Com p os i t e Dam

A rockfill dam consisting of a rockfill on thedownstream side and an earthfill on the upstreamside; the former for stability principally, the latterfor both imperviousness and stability.

2.73 Rockf i l l Dam

A dam composed of rock, either dumped in liftsor compacted in layers as a major structuralelement. An impervious membrane is used as thewater barrier and can be placed either within theembankment or on the upstream slooe ( seeFig. 15 ).

A movable dam consisting of a large steel cylinderplaced across the waterway between piers of

abutments and arranged to be rolled up clear of’the stream flow on an inclined rack track.

2.76 R o u n d H e a d B u t t r e ss D a m

I \

See 2.9.

a) &vtral’Earth Core

d) Central Thin Membiane

2.74 R e l l e d E a r t h D a m

A dam in which selected materials are placed inthin layers and compacted by rolling at propermoisture content. It can be a zoned earth dam ora homogeneous earth dam.

2.75 Rol l i ng Dam

b) Sloping Earth Core c) Upstream Core

e) &e&am Thin Membrane or Deck f) Dam with Rubble Retaining Zone

FIG. i5 ROCRPILL DAM TYPES

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Z-77 Rubble Dam

A da m const ru cted of rocks laid in place, with out

mortar .

2.78 Sausage Da m

A low da m const ru cted of cylinder s of loose rock

formed by wirenet wrappin g. The cylinders are

laid in either a horizont al or a vertical position.

Such dams are not impervious and are u sedprimar ily t o redu ce erosion, reta rd debris, et c.

2.79 Semihydraulic Fi l l Dam

An eart h dam in the const ru ction of which the

material has been tra nsported by some m eans

other th an wat er, an d some of it ha s been m oved

into place by the agency of water.

2.80 Sdmirigid Da m

An interm ediate class of da m between rigid an d

non-rigid type like rockfill da m.

2.81 S i n g le C e n t r e d D a m sThese da ms have one set of lines of cent re on t he

referen ce plan e. Both sides of each face ar e

described by the same circular arc.

2.82 S i n g le C u r v a t u r e D a m

An ar ch dam wh ich is curved in plan only.

2.83 Small Dam

A dam less th an 15 m in height an d which does

not fulfil an y of th e conditions of a large da ms.

I .S4&10 ( , P w t 8 ) :: 1592

2.84 So li d Gr a v i t y Da m

See 2.42.

2.85 Sp i l love r Bu t t r e s s Dam

Wher e flood water is a llowed t o be pa ssed over,

but tr ess ( see Fig. 16 ).

2.86 Spillway Dam

See 2.65.

2.87 St ee l Dam

A dam built of steei deck support ed on inclined

steel str ut s. There ar e two general types of this

da m: (a) ‘Direct-Str ut ted Steel Dam ’ ( see 2.90 )

in which th e load is tran sFerr ed Corn th e deck to

th e foundat ions thr ough inclined str ut s ( ree

Fig. 5 ), and (b) ‘Can tilevered Steel Dam ’

( see 2.12 ), which cons ists of va ria tions of th e

direct strut ted type, in which the section of th e

bent su pporting the upper part oi th e deck is

form ed int o a cant ilever tr us s ( see Fig. 17 ).

2.88 S t o r a g e D a m

This dam impounds water in per iods of surplus

sup ply for u se in per iods of deficient su pply. Thes e

periods may be seasonal, annual or longer.

2.L9 Stra ight Gr avity Dam

A gravity dam straight in plan.

2.?0 T h i c k A r c h D a m

It is an ar ch dam wher e th e th ickness of base is

between O-3 times t o 0.5 times the height.

FIQ. 16 SPILL &'ER BUTTRESSDAM

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IS ‘4410 ( Pa r t 8 ) I 1992

FIG. 17 TYPICAL CANTILBVBRTYPB STEEL DAM

2 .91 Thin Arch Dam

It is an arch dam where the thickness of base isless than O-2 times the height.

2.92 Til&ng Dam

An overflow dam so constructed that a top sectionwill tilt and allow the passage of excess water;sections are set to tilt at various elevations of the

impounding water.

2.93 Timber Dam

A dam constructed of framed timbers. The dammay be of cellular or crib construction, fil led withrock to give it stabili ty, or it may attain suchstability through its form of design.

2.94 Timber A - F r a m e D a m

A fixed dam, usually low in height, built ofsquared timbers with a plank facing, and not

fil led with rock. The bents or’ buttresses areframed like the letter ‘A’ lying on its side, withapex upstream, one side forming a sill and theother the support for the deck. The deck usuallymakes an angle of less than 30 degrees with thehorizontal.

2.95 T r u s s B u t t r e s s D a m

A type of deck dam in which the massive butt&-ses are replaced by reinfored concrete trusses tosupport the deck slab.

2.96 T w o - C e n t e r e d D a m

These dams have two sets of lines of centres, oneset for each side of the dam. The two sets arecoplanear on the reference plane. Each face of anarch element is described by two circular arcscompounded at the reference plane.

2.97 Va r i a b le C e n t r e D a m

An arch dam whose arch centres for either orboth the upstream face and the downstream facevary in location with respect to axis centre atdifferent elevations. The arches may be of uniformthickness or variable thickness with or withoutfil lets. Cantilevers vary in shape and thickness atdifferent locations within the dam according tothe difference in curvature between the archesand according to the kind of arches used ( SMFig. 18 ).

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2 .98 Va r i ab l e Ra d i us Ar ch Dam

See2.97.

2.99 Wicket Dam

A movable dam consisting of a sill and a numberof wickets or rectangular panels of wood or iron,hinged on the sill and held up nearly vertical by a

hanged prop that has a footing on the sill andcan be tripped, dropping the wickets flat on thesill.

3 TERMS RELATING TO DAM SECTIONS

3.1 Ab u t m e n t o f a B e a m E l e m e n t

It is the surface at either end of the beam, whichcontacts the rock of the canyon wall.

3.2 A b u t m e n t P a d s

It is a structure between arch dam and theirfoundations.

.3.3 Apron

A floor or lining of concrete, timber, stone, etc, toprotect a surface from erosion, such as thepavement below chutes, spillways, or the toe ofdam.

3.4 A r c h A b a t m e n t -

The abutment of an arch element is the surfaceat either end of the arch, which contacts the rockof the canyon wall. Arch loads are transferredthrough the arch abutments to the canyon walls.

3.5 Ar ch Can t i leve r Sec t i onIt is a vertical section taken normal to the extra-dos usually oriented with the reservoir on theleft.

3.6 A r c h C e n t r e L i n e

The locus of all median points of the thickness ofan arch section.

3.7 A r c h E l e m e n t

An arch element, or arch, is a portion of a dambounded by two horizontal planes at distances of

one unit apart.3.8 Arch Section

A section representative of an arch dam as itwould appear if cut by a horizontal plane.

3.9 Axis

See 3.10.

3.10 Axis of Dam

The olane or curved surface arbitrarilv chosen bvthe design or approach as

cross section to which theof the dam can be referred.

I I

a line in plan or in

horizontal dimension

iI?+ 410 ( P a r t 8 1;‘: i999

3 .11 Beam El em en t o r B-m

It is a portion of a gravity dam bounded by twohorizontal planes one metre apart.

3.12 Beam Sec t i on

A horizontal section through the dam.

3.13 B e d r o c k

Any in-situ rock underlying the overall burdenmaterial.

3.14 B l a n k e t

A cover of pervious, semi-pervious or imperviousmaterial.

3.15 Blanketing

The covering of one type of material by a layer ofanother type of material.

3.16 B u c k e t

A curved surface provided at the toe of anoverflow dam to deflect the overflowingwater in such a manner as to reduce erosionat the toe of dam.

The transition curve between the down-stream face of an overflow dam and itsapron.

3 .17 Can t i l eve r E l em en t s

The cantilever element, or cantilever, is that

portion of a dam, which is contained within twovertical radial planes or two vertical planes normalto the dam axis spaced a unit distance apart atthe axis. Cantilevers of arch dams, other thanone of the constant-centre typ, have warped sidesowing to the fact that the arch centre line radiiare not the same at all elevations. The crowncantilever is located at the point of maximumdepth.

3.18 Can t i l eve r Sec t i on

It is a vertical section taken normal to the axis,

usually oriented with the reservoir on the left.

3.19 Canyon or C a n o n

A deep valley with high steep slopes generallywith a stream at the bottom. Canyons are charac-teristic of regions where, owing to aridity or togreat slope, the downward cutting of the streamgreatly exceeds weathering. The width at the topis generally several kilometres and at the bottomabout that of the stream distinguish by its greatsize and rugged steep slopes.

3.20 C a n y o n S h a p e

Same as ‘Valley Shape’.

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3 . 2 1 C a n y o n S h a p e F a c t o r

I t i s t h e ratio of the perimeter of the foundationsand abutments of a dam measured along its axisand the maximum height of the dam.

3.22 Canyon Wall

I t is the side face. of the long narrow canyonvalley along which the dam abutts.

3.23 C ent ra l Ang le o f Arch D am

Central angle of arch is the angle bounded by linesradiating from the arch extrados centre to pointsof intersection of the arch centre line with theabutments ( see Fig. 2 ).

3.24 C o n s t r u c t i o n S l u i c e

It is an opening through the body of the dam forpassing or diverting water during the constructionperiod of dam.

3.25 C o n t r o l H o u s e

A structure usually built at the top of the shaftand employed as a means of access to the gatechamber. The house usually shelters the remotecontrol mechanism, a hoist, generator set, ventila-ting system, heater, gate height indicator, etc.

3.26 Core

A wall of concrete or masonry, sheet piling, orcompacted puddled clay built inside an earth orrockfill dam to reduce percolation. It is also called‘Core Wall’ ( seeFig. 7 ).

3.27 C ore W al l

Se e 3.26.

3.28 C r e s t

The line or area defining the top of the dam orthe overflow section of a spillway.

3.29 Crest L e n g t h

The length as measured along the crest of thedam.

3.30 Crest Lavel

The elevation of the crest of a dam above meansea level.

3.31 C utof f

A wall or diaphragm of concrete or steel, or atrench filled with impervious earth or grout cur-tain, extending into the foundation of a dam, andeither making a watertight connection with thedam or its impervious facing or extending intothe body of the dam a considerable distance; itspurpose is the prevention or reduction of passageof water under the dam and the foundation mate-

rial or through the upper layers of the foundationmaterial ( see Fig. 7 ).

3.32 C utof f B u t t r e s s

Cross walls projecting into embankment fromspillway abutments, power-house walls, or other-concrete walls extending through the structure in..an upstream and downstream direction.

3.33 C utof f C o l l a r s

In all closed conduit layouts, seepage of water.along the contact plane of the outlet conduit andthe dam embankment is minimized by the cons-truction of projecting fins or cutoff collars aroundthe exterior circumference of the conduit parti-.cularly through the upstream and the central.portion of the impervious section of the dam.

3.34 C utof f Trench

An excavation in the base of a dam to be filleck:with relatively impervious material to reducepercolation through the foundatioa.

3.35 Cutoff Wal l

See 3.31.

3,36 Dam Axis

Se e3.10.

3 .37 D ow ns t r e am P ro jec t ion

It is the horizontal distance from the intrados te,the axis on a line normal to the extrados,

3.38 D o w n s t r e a m S h e l l o r D o w n s t r e a m F i l l

Se e3.84.

3 .39 D ow ns t r e am Toe

Junction of the downstream slope or face of adam with the ground surface or downstream river-bed.

3.40 D ra inage W el l s

‘Openings between the watertight arches and the.supporting mass in a dam with levy-type facing.

3.41 Drainage Fi l t e r

Se e 3.55.

3 .42 Drain Wel l

A deep cylindrical drain located in the founda-.tions of a dam or downstream of it to relieve theseepage pressures in pervious strata too deep to bereached by trench drains, and to drain localizedconcentrations of seepage, where a continuoustrench of pervious blanket is not warranted. They~are also employed to correct developed bedseepage condiiiohs.

3.43 E l e v a t o r T o w e r

Tower containing liftsat different elevations. to give access to galleries.

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3 .44 Ex t rados

It is the curved upstream surface of horizontalarch elements.

3.45 Fi l le t

.A fillet is an increase in thickness of a dam at andnear the abutments of the arches or the base ofthe cantilevers. Fillets are usually placed at the

downstream face, but may also be used at theupstream edge of the base of the maximum canti-levers.

.3.46 Fi l t e r

One or more layers of porous materials so arran-ged as to prevent movement of finer soil particlestowards coarser strata by seepage flow of water( see Fig. 7 ).

3.47 F o o t i n g

Portion of the foundation of a structure thattransmits loads directly to the soil.

IS 4410 ( P a r t 8 ) : 1852

3.54 H o i s t i n g C h a m b e r

A chamber built to house remote control hoistingmechanism.

3.55 H o r i z o n t a l D r a i n a g e B la n k e t

A blanket of pervious material constructed at thefoundation from downstream toe of the imperviouszone to the landside in a levee or downstream sideof an earth dam, to permit the discharge of see-

page flow without movement of finer soil particlesand to minimize the possibility of piping failure,either of the blowout or subsurface erosion type.It is also called ‘Pervious Blanket’ or ‘DraingeFilter’.

3.56 H y d r a u l i c H e i g h t

The hydraulic height is the difference in elevation.between the lowest point in original stream bedat the axis of the dam and the highest controlledwater surface.

3.57 I m p e r v i o u s B l a n k &

3.48 F r e e B o a r dA blanket which is impervious.

The vertical distance between a specified water 3*58 Jnsu1atin8 Wa’1.surface and top of the non-overflow section of the A thin wall of reinforced concrete provided along-dam. the downstream face of a dam and at a little

3 .49 G a t e C ham ber o f S lu i ce Wel l

An opening located within the abutment or mainbody of the dam or the dam embankment withinwhich the regulating gates or emergency gates areinstalled. The lower portion of the chamber provi-des an anchorage for the gates and liner, whilethe upper portion furnishes working space for theremoval oft he gate leaf and other parts for repair,and for the installation of the necessary controlmecharriaGi& The gate chamber is usually locatedupstream of the axis olthe &SE

3.50 G o r g e

a) A small canyon,

b) A narrow passage between mountains,

c) A ravine.

.3.51 H e e l

The upstream edge of the base of a masonry dam.It is also called ‘Upstream Toe’.

distance from it with a view to protect it fromfrost damage in cold countries.

3 .59 In t r ados

It is the curved downstream surface of horizontalarch elements.

3.60 I n v e r t e d F i l t e r

A 1a)er or layers of pervious or semi-perviousmaterial having a controlled gradation to providedrainage and prevent movement of finear soilparticles due to seepage flow of water. It is alsoch!!:d ‘Protective Filter’.

3.61 I r r i g a t i o n S l u i c e

It is an opening through the body of ihe dam forpassing water for irrigation purposes.

3.62 Key Wall

A cutoff wall extending from the cutoff trench

into the bed rock or impervious subsurfacestratum.

3.52 H e e l L i n e 3 .63 Leng th o f Arch D am

The line joining the upstream slope or face of a It is the length along a curve which is concentricdam with the valley floor or upstream blanket. Itis also called Upstream Toe Line’.

with the extrados and passes through the midpointof the arch thickness at the crown.

3.53 H eigh t o f C an t i l eve r 3 .64 Len g th o f D am

It is the vertical distance between the base eleva- The extent of barrier in dam and integral featurestion of the cantilever section and the top of dam constructed between excavated abutments. Thewhich may or may not be the top arch. length is measured along the axis of the dam at

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l S .c l J l O ( Pa r t 8 ,J ,: 1992

the elevation of the top. of the main body of thedam or of the roadway surface exclusive of anyabutment spillway. If the spillway lies whollywithin the dam and not in any area especiallyexcavated for the spillway, the length should bethe length along the axis extended through thespillway to the abutment contacts. Also called‘Crest Length’.

3.65 Li ne o f Ar ch Cen t r e sA line passing through the arch centres in planor profile. Arch centres are located so that theywill be on smooth profile curves in a verticalplane, In the case of a constant centre type ofarch dam, a single vertical line will be the locusof the arch centres. For variable centre dams,separate profile curves will be the loci of archcentres for the upstream face, the centre line, andthe downstream face. In the case of symmetricallayouts, the vertical plane through the arch cen-tres will generally intersect the dam at the placeof maximum deflection ( see also 3.6 ).

3.66 M ai n Body

The structural part of a dam above foundation.

3.67 M axi m um Bas e Wi d t h

Horizontal distance between the outer points ofthe heel and toe of the cross section of a darn orspillway.

3.68 M axi m um He i gh t o f Dam

See3.93.

3 .69 Ove r hang

a) The portion of spillway crest of the damprojecting upstream for eff icient waterdischarge.

3.70 P a r t i -

A cutoff extending into the underlying stratum,but not reaching an impervious subsurfacestratum.

3.71 Perforated CutoffA nonwatertight cutoff made of material such as

steel sheet piles. It i s also called ‘Semi-imperviousCutoff’.

3.72 Positive Cutoff or Complete Cutoff

A cutoff extending to or into the bed rock or intoimpermeable subsurface stratum.

3.73 Pressure Relief Well or Drain Well orRelief Well

See 3.42.

3.74 Profile

A profile is a developed elevation of the iptersec--tion of the dam with the original ground surface,rock surface, limit of excavation, or any other.surface along a designed line, such as the axis, orthe upstream of downstream toe. Profiles arecommonly classif ied as U-shaped or V-shaped,-with variation between these two classif ications.

3.75 Protective FilterSee 3.60.

3.76 Pulvino ( Cushion )

It is a type of abutment pad provided to protectabutment rock against weathering. It acts as atransition structure between the arch and the rock,..distributes the stresses on the rock or bridge overareas and of weak rock and also smoothens out.any irregularities in the foundation.

3.77 Relief Well

Se e3.73.

3.78 Revetment

Material, such as rock, concrete blocks or mattres-ses, placed on the bottom or banks of a river to-prevent or minimize erosion.

3.79 Ri ve r s i de B l anke t

See 3.104.

3.80 Rock Toe

The downstream toe of an earth dam or other,structure constructed of rock materials.

3.81 Sec t i on o f an Ar ch Dam

b) In an arch dam, the portbeyond the width of top ar

16

3.82 Semi-impervious Cutoff

Ses 3.71.

3.83 Service Outlet

Outlets provided in the body of the dam through

which water is drawn off for actual use. These areprovided with trash racks.

3.84 Shell

A component of an arch dam constructed of-pervious or semi-pervious materials upstream anddownstream of the core or membrane. The up-.stream portion is called ‘Upstream Shell’ and thedownstream portion ‘Downstream Shell’. Shell is-also called ‘Shoulder’ ( see Fig. 7 ).

3.85 Shoulder

See 3.84.

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3.86 Shot C o n c r e t e C u t o f f

se e 3.92.

3.87. Bodes

It is a type of abutment pad; it varies in depthaccording to requirements of symmetry of thearches and excavation of the abutments and is

placed as an integral part of the dam.3.88 sod

A surface layar of soil matted or held together byroots, rhizomes and stolons of grasses and otherherbs ( see Fig. 7 )._ This is normally used in thedownstream surface of earth dam for preventingrain cuts and is also known as ‘Turfing’.

3.89 Slu i ce

a) A conduit, fitted with a gate, for carryingwater at high velocity.

b) An opening in a structure through which

anything flows, for example, water, ice ordebris.

c) To cause water to flow at high velocitiesfor wastage, for purpose of excavation,ejecting debris, transporting ways, etc.

3.90 Slu i c ing O u t l e t o r D es i lt i ng S lu i ce

Outlet in the body of the dam, used for scouringor sluicing out settled material from the reservoir.

3.91 S t o p e d C u t o f f

Cu to f f constructed by utilising undergroundmining methods for excavation, then backfill ing

the excavation with concrete or other selectedmaterial.

3.92 S t u b C o n c r e t e C u t o f f

Cutoff employed in conjunction with a level rockfoundations or with a deep soi l trenches cutoffwhere a good seal of earth on rock is diff icult toobtain. Its purpose is to increase to path ofseepage and prevent leakage along the rock-soilcontact surface.

3.93 S t r u c t u r a l H e i g h t o f D a m

It is the vertical distance between the lowest

point in foundation and top of the dam. Thestructural height of an’ earth dam is the verticaldistance between the top of embankment and thelowest point in the excavated foundation area,including the main cutoff trench, if any, butexcluding small trenches or narrow back-filledareas whose width is less than 10 m. The topelevation does not include the crown of any road-way over the dam. The structural height of amasonry dam is the vertical distance between thetop of the dam and the lowest point of theexcavated foundation area, whose width is lessthan 10 m. The top of the dam is the crown of

the roadway, if a roadway is taken over the dam,otherwise it is the level of the walkway.

3.94 Supporting Ma8s.

The portion of the body of a dam supporting thelevy-type facing.

3.95 T h i c k n e s s o f Arch Da m

It is the length of a line along an extrados radiusfrom the upstream to the downstream face which

passes through the point.3.98 Tltickness of Da m

Thickness of a dam at any point is the distancebetween the upstream and downstream face alonga line normal to the axis through the point.

3.97 T h r u s t B l o c k

It is an artificial abutment and can be used:

i) to reduce length of an arch near the topof a dam canyons that widen rapidly;

ii) to reduce non-symmetry;

iii ) to spread the stress over wider area in case

of weak abutment rock;iv) to serve as an abutment where no natural

rock abutment exists;

v) to accommodate the spillway and to locateconduits where situation requires.

3.98 Toe D r a i n

A drain constructed at the downstream toe of anearth dam to collect and drain away the seepagethrough the dam and its foundation ( see Fig. 7 ).

3.99 Top W id th

Width at the top of the dam.3.100 T r a n s i t i o n F i l t e r

A component of an earth dam section ( with core )consisting of intermediate grade of material placedbetween the core and the shells to function like afilter, preventing lateral movement of fines fromthe core ( see Fig. 7 ).

3.101 T r a n s i t i o n Z o n e

It is the part of the section of an earth damoccupied by the transition fi lters placed betweentwo zones of an earth dam so as to prevent the

lateral movement of finer particles towards thecoarser zone.

3.102 T r e n c h D r a i n

A drain provided in the foundations of a dam tointercept seepage. When placed immediately aftera cutoff, it relieves any pressure that might deve-lop f rom possible ineffectiveness of the cutoff.

3.103 Turfing

See 3.8.

3.101 Upstream Blanket

An impervious blanket constructed from theupstream toe of impervious zone towards the

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* 4~1.0 ( Part.8 ) : 19%:

upstream of an earth dam or towards riverside ofa levee ( then called ‘Riverside Blanket’ ) wheresubs&&m’ is pervious, to control seepage byincreasing the resistance to seepage entry into thepervious substratum, thereby decreasing’ bothseepage flow and excess pressure downstream sideof the earth -dam or landward side of the levee( see Fig. 7 ).

4.6 Gal lery--. \I :‘. .-: ,_ ?.- ‘; _

A passageway in a dam for obtaining access tointerior parts, or to carry pipes or. t.o., -house-machinery.

4.7 G a t e G a l l e r y

3.105 U p s t r e a m S h e l l o r U p s t r e a m F i il

Se e3.84.

Gallery, made in a dam, to provide access to androom for, the mechanical equipment required for-

the operation of gates in outlet conduits, power-penstocks or spillway crests.

4.8 Grout ing G a l l e r y

3 .106 U ps t r eam Toe

Se e 3.51.

3 .107 U ps t r eam Toe L ine

Se e3.52.

3 .108 Val ley Sh ap e

It is the ratio of the width of the valley at crestlevel of dam to the depth of the valley below

crest level, it is also called canyon shape.

3.109 Voussoir

Gallery provided in a dam to locate the supply,.return and vent headers of the grout piping system;also the piping system for artificial cooling of the-blocks terminates in the galleries.

4.9 I n s p e c t i o n G a l l e r y

Gallery made in a dam to provide access to the-interior of the mass in order to inspect the struc-ture and study the structural behaviour of the

dam after completion. Foundation, drainage gateand grouting galleries also serve as inspectiongalleries ( see Fig. 9 ).

It is that smaller segment of a section of an archwhich, for ease of computation, is assumed tohave constant thickness.

4.10 P l u m -L i n e S h a f t o r C o ll im a t o r S h a f t

4 TERMS RE LATING TO GALLERI ES AND

O TH ER O PE N IN G IN TH E D AM S

A shaft located near the maximum section of adam in order to make observations of the move--ments of the dam with respect to the base.

4.11 Shaf t

4.1 Access G a l l e r y

A horizontal gallery connecting the gallery systemin the dam with the downstream face or featuresoutside the dam, such as power house or gatehouse. Also called ‘Adit’ or ‘Entrance Gallery’( see Fig. 9 )

4.2 Adit

See 4.1.

4 .3 D ra ina ge G a l l e ry

Vertical openings provided in the dam at suitableplaces for various purposes, such as for locationof headers of artificial cooling system, accommo-.

dation for measuring devices, for connecting).galleries by stairway, for elevator movement andfor hoisting equipment for inspection purpose

4.12 St i l l ing Wel l Shaf t

A special shaft, sometimes, included in the designof a dam, open to the reservoir below minimumreservoir level and containing a floating mecha-nism to record reservoir fluctuations,

A gallery in a masonry dam, parallel to the crestto intercept seepage from the water face and con-duct it away from the downstream face.

4 . 4 E n t r a n c e G a l l e r ySe e4.1.

4.13 S p i l l w a y T u n n e l

A tunnel used as a spillway outlet.

4.14 Weep Holes

4 .5 F o u n d a t i o n G a l le r y

18

A gallery providing drainage for water percolatingfrom the upstream face or seeping through thefoundations in a dam, generally extending thelength of the dam near the rock surface, conform-ing in elevation to the transverse profile of thecanyon; in plan it is near and parallel to the axisof the dam. It is from this gallery that the holesfor the main grout curtain are drilled and grouted,and also from which foundation drain holes are

drilled.

Holes used for reduction of uplift pressure under-aprons and excessive pressure behind walls.

5 TERMS RELATING TO APPURTENANTWORKS TO A DAM

5.1 Bye-Pass Outlet

It is a sluice provided in a dam to bye-pass waterto flow from reservoir to canal or river down--stream, when power house is not functioning.

5.2 Divide Wall

A wall extending along the spillway to separate:

overflowing water, wherever necessary.

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. 5 .3 D ra inage H ole .,

Holes drilled into the dam foundations for reliev-ing uplift pressures.

5 .4 E m e r g e n c y G a t e

Gates used for controlling flow through sluiceswhen any repairs or maintenance or both arerequired to be carried out to service gates. Theseare generally designed for full gate opening.

5.5 F i s h L a d d e r

Structure constructed for allowing fish from riverdownstream pass up into the reservoir.

5.6 P e n s t o c k

Pressure pipes usually made of steel which conveywater from the intake to the turbine in hydro-electric power-house.

5.7 P i e r

Concrete or masonry structure constructed overthe spillways for supporting bridge decking, spill-way gates and hoist operating mechanism.

5.8 P o w e r H o u s e

A building housing the generating and controllingequipment of a hydroelectric power generationsystem.

5.9 R e t a i n i n g Wall

Concrete or masonry wall constructed to retainbackfill or water.

5.10 S l u i c e G a t e o r S e r v i c e G a t eGates used for allowing water to flow through,from the reservoir to downstream at a controlledrate.

5.11 T r a i n i n g W a l l

Concrete or masonry wall constructed on overflow.section of the dam to guide the spillway water.

5.12 T r a s h R a c k

A grill or cement over at intake openings forpreventing the entry of suspended or floating

material into the water conductor system. Trashfor fine/coarse openings depending upon thenature of the debris to be included.

6 TER M S R ELATIN G TO J O IN TS

6.1 A spha l t Sea l

Asphalt filler in a contraction or expansion jointfilled with asphalt to make it watertight.

6.2 Block

The portion of a dam between two transverse,joints constructed normal to the axis.

fS4irl-O.( Part 8 J I 1992

6.3 C l os u r e B l oc k o r C lo s u r e G a p

Closing gaps are provided in between blocks foradverse conditions due to temperature effects,foundation requirements, unusual size of the struc-ture and in stage construction. These are namedas shear slots twist slots depending upon thefunction.

6.4 C o n s t r u c t i o n J o i n t

The interface between the t&o successive placingsof earth masonry or concrete where bond ( andnot permanent separation ) is intended. Theseare classified into horizontal joints, transversejoints and longitudinal joints ( see Fig. 9 ).

6.5 C o n t r a c t i o n J o i n t

A joint provided ‘to localise and minimize development of cracks due to drying shrinkage andthermal variations.

6.6 E x p a n s i o n J o i n t

A joint provided in exposed members betweenfixed points to permit longitudinal expansion andcontraction when changes in temperature occur,and to permit vertical movement where differen-tial settlement is anticipated.

6.7 G r o u t S t o p

A type of waterstop to confine the extent ofgrouting used to seal joints.

6.8 H o r i z o n t a l J o i n t o r C o n s t r u c t i o n L i ft

A joint introduced between the lifts to providesufficient cooling between pours.

6.9 J o i n t s

A break between two pours of concrete done atsome interval of time; or a small open spaceforming a complete plane of separation betweencomponent of the structure with relation to trans-mission of stresses.

6.10 J o i n t D r a i n

Vertical drains provided in transverse or construc-tion joints as a precaution against development ofexcessive pressure in the joints during the cons-truction period and against seepage of reservoir

water through the joints during the operatingperiod ( see Fig. 9 ).

6.11 K eyw ays o r O ff se t s

Indentations or projections of some geometricalshape built on, or formed into, poured surfaces toprovide a degree of integral action with subsequentstructural additions.

6.12 Lift

The height, which is poured continuously at anytime and over which other lift is poured aftersufficient time is allowed for the pour to cool.

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35 4410 (:P ar t 8 ) t 1892

6 .1 3 L o n g i t u d i n a l C o n s t r u c t i o n J o i n t

See 6.13.

6 .1 4 L o n g i t u d i n a l J o i n t

a) A joint in the longitudinal direction of thedam or parallel to the axis of the dam andoffset at the transverse joints to form alongitudinal row of staggered columns,

b) Joint parallel to the lines of principalstress. It is also called ‘Longitudinal Cons-truction Joint’.

6.15 P e r i m e t r a l J o i n t

It is a joint provided between the dam and thefoundation pad or pulvino, commonly knoivn aspulvino perimetral joint. This joint is providedfor lower ‘and better distribution of stresses. Italso relieves tensile stress in the abutment extrados.

6.16 P o l y v i n y l C h l o r i d e S e a l s ,, .’

A type of seal manufactured in different shapesfrom the polyvinyl chloride material.

6.17 Seal

These are used to prevent the leakage of waterfrom the reservoir to the downstream face throughtransverse construction joints between constructionblocks.

6.i8 Sealing S t r i p s

Se e 6.22.

6 .1 9 S h e a r K e y o r S h e a r S lo t

These are regular projections provided in jointsin dam for transfer of load from one block toother through shear. The shear keys in transversejoints are designed to transfer horizontal shearand those in longitudinal joints are designed totake vertical shear.

6.26 T r a n s v e r s e Co n t r a c t i o n J o in t .

See 6.21.

6 .6 1 T r a n s v e r s e J o i n t

A joint provided normal to the axis of the damand extending entirely through the structuredividing it ( structure ) into separate blocks, witha view to preventing haphazard transverse crack-ing due to contractions of concrete. Also called‘Transverse Contraction Joint’.

6.22 T r a n s v e r s e J o in t S e a l s

Device provided in the transverse joint to preventleakage of water from the reservoir. These sealsare of copper, rubber, etc. Also called ‘SealingStrips’.

6.23 Vertical DrainsSee 6.10.

6.24 Vert ical Wells

See 6.10.

6 .25 Wat er S top s

Devices provided to prevent the flow of waterthrough the leaks or joints.

7 TERMS R ELATING TO GROUTING,

FOUNDATIONS TREATMENT AND,

DRAINAGE

7.1 Alluv iu m Grou t ing

Grouting of transported pervious media, such as.sand, gravel and single, with clay, cement, bento-nite andlor chemicals mixed in different propor-tions.

7.2 A r e a G r o u t i n g

In cases where large zones of fractured rock, lieat the foundation contact or where the zone of’broken rock within a fault has great width, the

entire zone of factured rock shall be grouted to a,shallow depth usually 3 to 1.0 m by using a grid.pattern. This type of grouting is referred to as-blanket grouting. It reduces leakage in the fractu-red zone and provides a more firm foundation forthe dam.

7 .3 B e n t o n i t e G r o u t i n g

Grouting in which bentonite with or without other-ingredients in the form of suspension is injectedunder pressure into a pervious medium to makesit watertight.

7.4 C i r c u l a t i n g S y s t e m

The piping arrangement by which grout is con-.veyed from the grout pump to the grout holeand through a return line from the hole to thegrout pump.

7.5 Chemical G r o u t i n g

Grouting in which chemicals are injected underpressure into a pervious medium to make it water-tight by formation of gels.

7.6 Contact Grouting

Contact grouting is a sealing operation intended.

to bring about as nearly as possible a fully boun-ded contact between a.ny concrete structure andthe adjacent rock.

7.7 C u r t a i n G r o u t i n g

It consists of forming an approximately verticalgrout curtain of moderate thickness below a damto control seepage of water.

7.8 D e n t a l T r e a t m e n t

It consists of excavating objectionable materialsfrom solution cavities, fault zones, seams or other

rock imperfections and filling with concrete thecavities so excavated.

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7.9 Drainage

It is the disposal of surface and seepage water inthe abutments, foundation and the body of thedam.

7.10 F o u n d a t i o n D r a i n a g e H o l e s

Holes drilled from the foundation

drainage gallery of dam into thedownstream of high pressure groutintercept seepage through the curtainrelieve uplift pressure.

gallery or

foundation,curtain toand thus to

7.11 Full Depth Grouting

A method of grouting in which the entire depthof a hole is grouted in one operation by connectingthe grout supply line to the manifold at the topof the hole.

7.12 G r o u t

A fluid or Auid mixture that can be poured or

injected easily.

7.13 Grout Curtain

A diaphragm or curtain in which the foundationis made impervious by grouting process.

7.14 G r o u t i n g

A process of pouring or injecting grout in thejoints, hollows, cracks, seatis, faults, shatteredzones or fracture zones, etc.

7.15 G u n i t i n g

A process of laying membrane of an intimatemixture of sand and cement pneumatically con-veyed in a dry state to the nozzle of the cementgun where water is added immediately priorto expulsion and shot into place.

7.16 I n t e r n a l Dr a i n a g e o f D a m

It usually comprises porous concrete blocks/formeddrains at the contraction joints and in the bodyof the dam.

7.17 J o in t G r o u t i n g

Joint grouting consists in grouting constructionjoints between adjacent units of a concrete struc-ture in order to join them together into a singleunit.

7.18 M ani f o ld o r Hea de r

The piping arrangement at the top of the hole forconnecting the line to the hole.

7.19 Multiple G r o u t i n g

A thick grout is occasionally used during the firststage to seal leaks; as soon as the grout in the

rock has attained a partial set the hole is washedand redrilled then regrouted with a thinner mix.

IS4410(Part8) :1992

7.20 Packer

The device used in the hole to segregate part ofa hole for grouting or percolation testing.

7.21 Packer G r o u t i n g

The use of expandable implements, such aspackers, to isolate sections of a grout hole and

thereby enable the application of grout, underpressure only, in a portion of the hole.

7.22 Pattern

Arrangement of holes in plan and vertical section.

7.23 Percolation Test

Pumping of water into a hole with or withoutpressure through a direct connection or in diffe-rent sections of hole using packers and measuringwater intake for determining permeability charac-teristics. It is also called ‘Water Percolation Test’.

7.24 Porous Concrete Drains/FormedDrains

These drains are provided to intercept the seepagewater and such seepage water shall ultimately belet out into drainage gallery system. For masonrydams, drains through porous concrete blocks areprovided and for concrete dams there shall beformed drains.

7.25 Pressure Grouting

It is a process of injecting under pressure, a fluidsealing material into the inaccessible formations

or places through specially drilled holes for thepurpose of sealing off or filling joint seams fissuresor any other openings.

7.26 Primary Holes

In split spacing grouting the first set of holes arereferred to as ‘Original Holes’ or ‘Primary Holes’.

7.27 Rip-Rap

It is the layer of large size blocks of rock orconcrete over the top surface of earth or rockfillsection of the dam to protect the underlying layer

from erosion.7.28 S h e a r K e y

A longitudinal trench in the foundation of con-crete/masonry dam and backfilled with concretein order to increase the resistance against sliding.

7.29 Si ng l e L i ne Sys t em

The piping arrangement by which grout is con-veyed from a grout pump to grout hole througha single line of pipe without a return line.

7.30 S in g l e S t a g e G r o u t i n g

Same as ‘Full Depth Grouting’.

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IS 4410 ( P u t 8 ) t 1982

7 .31 Sp l i t Spac i ng Gr ou t i ng M e t hod

A sequence of drilling and grouting holes in whichwidely spaced holes and drilled and groutedinitially and the spacing is sub-divided by inter-mediate holes. The initial set of holes are calledprimary holes and intermediate holes are termedas secondary, tertiary, etc, according to thesequence of subdivision.

7.32 St age

A partial depth of holes treated or to be treated.

7.33 S t a g e G r o u t i n g

Grouting consisting of drilling a hole to a limiteddepth or to the intersection with an open seam,grouting to that depth, cleaning out the holeafter the grout has taken its initial set, and thendrilling and grouting the next stage. The processis repeated, using higher pressures for each

successive stage until the final depth is reached.Also known as ‘Down-stage Grouting’ or ‘Succes-sive Grouting’.

7.34 S u b s u r f a c e D r a i n a g e

It is provided for slope protection and alongabutments so as to relieve building up of waterpressure behind the dam and the appurtenantworks.

7.35 Succes s i ve Gr ou t i ng

See 7.33.

7 .36 Su r f ace Dr a i nage

It is provided for all open surfaces of the dam.

7.37 Was h i ng

Washing of the walls of the grout hole by waterunder pressure after completion of drilling butbefore grout injection.

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Stamhrd Mark

The use of the Standard Mark is governed by the provisions of the Bureau of IndianStunahrdr Act, 1986 and the Rules and Regulations made thereunder. The Standard Mark onproducts covered by an Indian Standard conveys the assurance that they have beenproduced to comply with the requirements of that standard under a well defined system ofinspection, testing and quality control which is devised and supervised by BIS and operatedby the producer. Standard marked products are also continuously checked by BIS for con-formity to that standard as a further safeguard. Details of conditions under which a licencefor the use of the Standard Mark may be granted to manufacturers or producers may beobtained from the Bureau of Indian Standards.

8/3/2019 4410_8


1.

heap of Indian Staudards

BLS is a statutory institution established undel the Bureau of Indian Stan dards Act, 1986 to promotzharmonious develapment of the activities of standardization, n&king and quality certification of goodsand attending to connected mat!ers in the country.

BIS has the copyright of all its publications. No part of these publications may be reproduced in anyform without 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.

Revision of Indian Standards

Indian Standards are reviewed periodically and revised, when necessary and amendments, if any, areissued from time to time. Users of Indian Standards should ascertain that they are in possession of thelatest amendments or edition. Comments on this Indian Standard may be sent to BIS giving thefollowing reference:

Dot: No RVD 2 ( 4334 )

Amendments I ssued Since P ublication

Amend No. Date of Issue Text Affected

BUREAU OF INDIAN STANDARDS

Headquarters :

Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi 110002Telephones : 331 01 31, 331 13 75

Telegrams : Manaksanstha( Common to all Oflices )

Regional Offices ; Telephone

Central : Manan Bhavan, 9 Bhadur Shah Zafar Marg 331 01 31NEW DELHI 110002 1 331 13 75

Eastern : l/l4 C. I. T. Scheme VII M, V. I. P. Road, ManiktolaCALCUTTA 7tXlB54

87 86 62

Northern i SC0 445-446, Sector 35-C, CHANDIGARH 160036 53 38 43

Southern I C. I. T. Campus, IV Croat Road, MADRAS 600113 235 02 16

Western f Manakalaya, E9 MIDC, Marol, Andheri ( East )BOMBAY 400093

632 92 95

Branches : AHMADABAD. BANGALORE BHOPAL. BHUBANESHWAR.COIMBATORE. FARIDABAD. GHAZIABAD. GUWAHATI. HYDERABAD.JAIPUR. KANPUR. LUCKNOW. PATNA. ‘THIRUVANANTHAPURAM.

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