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1.What is the bucldil11 The U121eriaithat 18ret~tneo bv the wail is retelted to as BacKtill. A ~etatning wall help!: in maintaining the bound !lrirfaceat di£f~ent ~le'.'~ti.<m'3 on dth(~t'side of it. I J. What

1sUte object ora retatnang

wa1J1

I.RetaitUngwalls helps m maintainingthe ground S'wtace at dtlterent elevations on either side of it. The ~arth retained may be natural soil (or) filled up :)Oil. ,

2. Retamingwall may rctamwater also.

3. What are retalDing waH 1 Reta1Jl1Ilgwail 18a strUc1U1'~ J8used to hold back a 80il maS8. A retammg wall helps in maintaining the ground surfac~ at different elevation on either side of it . It will also r~lain Wittg-. 4.mUlt are gravity walls? Tnese walls depends upon their weIght tor stability. The walls are usually '~onstroctedof plain conCt'ete (or) !viasO'tUi.Such walls are economical for small height.

5. What are semi gravity waJls? Size ot the section ot' a retaining wall may be reduced 11a small am01mtof reinforcement is provided nem-the back face. Suchwallf: are 1moW'1as semi gravity walls. ' 6. what are the cantilever retaining waii? , CanDlever retainiDg walls are made ot'reintorced Cement cQncrete. The wall consists of st~m, and a base fJIab cast monolithicaUy. This type of wall is found to be ~wnomi~al up 10 a hl;iighlof 6 108m. 7. What are counter lort .retaining v.waJIs'l Coumer tOrt reiamtng wall w1l1 have thm vertical slabs known as counter forts across the vertical stem at regular mtervals. The CO\U1ter fort tie the vertical stem with th~ b~ lIiab. 'fh1;)pUl~ of providirig th~ ~owu~r foIl ililO r~u~~ thl;i sheartorce and bending moments m the vertIcaJ stem and thl~ ba.'ie sJab. The counterfort retaining walls are economical for a hcight more than 6to8m.

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8. What Is pt:IUJtlcequilibrium'!

A JIUI88ot"sou is said to be in 1bcsIaio ot ptasuc equilibrium if the iatlure 18UlCtplem. or imminent at an points within the soil mass. . . 9. what is toea! staw of plasUCequWbrlum7 Whenever taliure ISmunmem only m a smaH pomon ot the mass such that produced by the yielding of retaining structure in the soil mass adjacent to it. Such a situation is ~fmc:d io as loca1swe of plastic equilibrium IU.what Is active earth pressure7 .rhe

pressure exerted by the sol1on the retaining wall. UluSmaking tile waU10

making the wall to mow away from the back filled soilmass is knownas activeearth pn:sSUI'C.Active pn:sSUI'ClCllds W Iurcich(expands)

horizonlally.

11.What is earth pressure at rest7 The lateral earth preS8U1"C is called at rest pressure wilen the sou mass IS nm subjected to any lateral yi~lding(or) mowment.this case occurs when the retaining waU is finn1y fixc:d al ils lOp and is nol aUowc:d w rowc;(or)move latc:ra11yBridge abutmenl wall which is res1ramed at its top by bridge slab.

U. what II passive earth pressure7 The pressure or resistance which soil develops m response 10movemem of the retaining wan towards it is ca11edthe passive earth pressure. passive pressure tends to ~mp~88 hOrU.omally.(c:g);pI'C8SUI'C acting on an an\)hor Nwk. lJ. What .Iscoeiliclent of earth pressure at rest 'f The coefficient ot" earth pressure at resi is the ratio of the intensity ot"earth pressure at rest to the vertical stress at a specified depth(ko}.

~=oh/GV 14.What is active case sUp Une7 In rankine active state the coefficient of active earth Pressure is given by Ie. - l-sin<1>/l+sin<1> = tan'\.u..n) H""Il\.Nth\; angl", mad\; by ih", failW\; pliw\; with hUliwntal

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15. what is passive ('.ftJJeslip Une? Tn Rankine!" passive state the coefficient of pa.qsive earth pressure is given by Kp=l +snutJl-sin$'-='tdn1

(4""'2)

Thus the angle made by the t,1l1ure piane Wl111tIlC hOnzonta118 (4:>-ql/:L}tor the paSSIVe c3fle.

lo.What ISsurcharge angle1 Sometim~, the surface of the backfill will be inclined to the horizont~l. 111i~iR ~nsideredto be illclhlOOsurclw'g,e and tbe ~ of inc1in1aioilof tbe backfill with tbe honzonmi IScalled the angle ot surcharge. 17. Wbat are the assumptions in Hankine's

in IDe

earth pressure t.!leary'!

SOll18 18OU'OpJCand homogeneous.

(ii) The rupture fPm3CCif!a.plmc surface. (ill) Failun: i.slwOdim~nsiona1. (lViThewall sur.tacc ISsmooth. (v) The back of the wan is vertical (vi) The:soil i.scohc:sionlc:sssoil. UJ. What are sUp IIDes1 Slip lines are fail\U'P.plancs alonG;which backfill soil mass is expected fa move, when the lateral moveroent iDallowed in the ~Wnin8 wan. In case of Rankine active state the slip lines makes an angle of (4S+cj>i2)withdie horizontal In case ofRankines passive state, the slip line make8 an angle of (4S~IJ!I2) '\\ith the horizonbL 19.wbat ISthe subme~ed

baclalU'!

The backtill gets submerged due to rise ot' groundwater leveL ,Forthe submerged portion of the backfill, the lateral pN6SU1'O at any depth is the awn of (i) A~tivc:earth pre:ssUl'C' du~ to subme:rgc:dunit wc:igbtof the;soil mass and (ii) HydroslatJc pressure '

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1U.What AsfaUure wedge? The tnangular mass at'solls between tbe ropiure plane and the backat the wan is known as failure wedge.

11.wbat are buttressed walls? Bettressed walJ5 are similar to counteJport walls expept Brackets (or) buttress walls are provided on the opposite Side of the backfill. 11. What are cOJUugate pUU1e1'! The vlanes carrying major and minor piincipal stresses are called conjugaie planes. Both planes arc perpcndict4ar to cadi other. In soil problems, the miUorprincipal stress is the verticalsIRSS d,"" 10 (I) selt weight at'the saiL (ii) Super imposed l~d The)minor principal iSIRSSis Ihe)hOlimnla1sIRss du~ lo (i) selt"weigbt ot"tbe soil (ii) 6upe!'imporied load 13. Wbat are co!Uugate stress'f In soil problems,botb major and minor principal stresses are tenned as conjugaie stresses. The planes canying both the stresses are called conjugate stre6&eS. Th" major priIt~ipall1lr~s8is ill~ vC1fucalsIRss du~ 10 (J}settweight ot the soil. (ii)Supcr imposed load Th~ minor principal slrc:ssis Ih~hori4lontalslrells ~ lo (i) scJfwcigbt of the soil . (ii) super imposed load.

Z4.wbat AstJIe percentage of strain reqwredto !Sands?

mobiuse active pressure In loose

10 case ot'loosc sanda, about O.S%horizontal strain is Required to mobiliso acaw pressuro. Zs.wnat is the percentage o'-strain reqUired to mobillse passive pressure in sands? For dense sand --+ 2% afborlzonul stt'ain Far loose sand -. lS%at'horizomal stram

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activecondition?

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The inclination of failure plane to the horizonral in .-'\cuvecondition IS(45+012). . .

27.

passIVe earth pressure will always be greater titan actiVe earth

pressure. 2iS. The coetIiClenI oi'eanh pressurc'lS detined as tqe rano between horizontal stress to vertical me!!!! ."

29.

.

The coetticienrohartb pressure at rest, mtcrms at POISSlon'S 'Ratio is given by ("(/1-1).

30. In colwnb's meary of earth pre8sw'e the rupture &w1ace 1&assumed to the plane surface. 31.

passive earth resistance is mobilized behmd a wall when the wall is moving t~wards the backfill.

32.

RetaUU11g strUCtW"earc mostly designed tar active pressure.

33.

Earth {)I'CSSUfe at rest IS greater than the active pressure.

34.

critical depth of vertical cut in a clay of soil is 4c/"{

35.

what is depth 0" teDSJoncrack? It is the depth \11'to which the active pre88w:eis NegAlI1te.However it i8 well kniwn that the soils can not with stand tensile stresscs, tension cracks will develop in this zOnc.It will leads to thc soil not remain adhered to ih~ wall. For C-qlsolI. the depth at tension crack 1821venbY

Zo=2c1r n.

J6. wbid.ililLht!.:riu.:aI depLh? . It is the depth.up to which ,va1:1calcut can be made With Out providing latcr;Usuppo11. In caee ofc-qI soil ,the critical

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