Engg Services Civil Engineering Subjective Paper 2 2009

7/27/2019 Engg Services Civil Engineering Subjective Paper 2 2009

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1. (a) A metal l ic cube 30 cm s ide an d weighing 450 N1S lowered in to a t a n k ' conta ining a tw o fluidl ayer of w ate r an d mercury. Top edge of th e cubeis a t w ate r surface. Dete rmine th e posi t ion ofblock a t water -mercury interface wh en i t h a sreached equi l ibr ium.

(b) W a t e r is pUTnped from . a well t app ing a nunconfined aquifer a t a ra te o f 2400 m 3 /day. Ano-drawdown boundary exis ts a t a dis tance o f5 kill frOln the well centre . Assuming th e well to.be fully penet ra t ing , compute the s teady s ta tedrawdown a t the well face. Given Ini t ia lsa tura ted th ickness = 50 m, hydraul icconductivi ty - 20 111Iday, effective well rad ius =

10

1 m . 1(c) A l a rge s t r eam has a reoxygenat ion cons tan t of

0 4 per day. A t a velocity o f 085 111Is; an d a t th epoin t a t which an organic pol lu tan t i sdischarged , i t 1 S sa tura ted with oxygen a t10 mglL (Do = 0). Below th e outfal l , the u l t imated e ma n d for oxygen is found to be .20 mg/L a n dth e deoxygenat ion cons tan t is 02 p er day. W h a t is th e dissolved oxygen 483 km d o w n s t r e a m ? 1

(d ) (i) Expla in the te rm "op t imum mois tu recontent". How is i t affected by compac t ing 'effor t ?

(ii) Sta te th e factors affect ing field compac t ionof soil.

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2. (a) If th e veloci ty dist r ibut ion in a pipe is given by

u = u m ax ( 1 - ~ rw h e r e u is th e veloci ty a t any r a d ius r , ro is th er ad ius o f pipe an d u m ax is th e m a x i m u m veloci ty,f ind (i) average velocity an d (ii) kine t ic energycorrect ion factor.

(b) T h e recorded a n n u a l ra in fa l l from five r a inga ugcs ta t ions in a c a tc hm e n t an d th e cor respondingTh iessen polygon a r eas a re as follows .

Thiessen polygon a r eas (cm 2 ) Rainfa l l (cm)25 12530 1753 0 22510 2755 325

T h e scale of the m ap is 1 : 50,000. E s t ima te t h ~volume an d _ th e _m e a n depth of the rainfal l .Est ima te the average a n n u a l discharge a t th eout iet , i f the runoff coefficient of th e -cal:chlTIent is

10

03. 10(c) W a te r t ab l e In a c a na l cOJnmand receives a

r echa rge a t th e ra te 2 5 mTnlday. Sub-sur facedi tch dra ins a t a spac ing o f 2 !un a re prov ided forth e sub-sur face dra inage . E s t ima te t hem a x i m u m r i se o f t he w a te r t a b le a t s teadys ta te . G i v e n : hydrau l ic conduct ivi ty of t he soil =10 mlday , de p th o f th e imperv ious l aye r belowin i t ia l w a t e r t ab le posi t ion = 20 In. A s s u m e th edi tches to be ful ly pene t r a t ing . 10

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(d ) ( i ) A depos i t of f ine sand h a s a poros i ty o f45%. Est ima te th e cri t ical hydraul icg ra d i e n t to develop quicksand condi t ion i fth e specific gravi ty o f gra in is 27. 5

(ii) Design slow sa n d f i l ters for a popula t ion o f40,000 with a n average ra te o f w a t e rsupp ly of 150 l i t res p er capi ta p e r day.

3 . (a) A 10 '0 m wide r ec tangu la r channe l w i th bot toms lope o f 0-00016 carr ies a discharge of 22,92 m 3 /sa t a normal dep th o f 2-0 m an d cri t ical dep th of0-8 m_ The dep th immedia te ly u p s t re a m o f d a mis 10-0 m_ C o m p u t e the l eng th o f th e sur faceprofi le be tween 10-0 m an d 6-0 m us ing Chow'sor s tep method_ Take s tep of 2-0 m a n d a s s u m eM = 3-0 an d N = 3-33 an d Manning ' s n = 0-015.T h e l eng th 'of surface profi le by Chow's meth o dbe tween tw o dep ths is given by

Ynx 2 - x l = So [(u 2 - u l ) - (F(u2 , N) - Feul . N) +

U:f JN !F(v2 , J ) - F(v l , J)lJ.u F(u, N ) v F(v, J)5 0-01 9 0-0274 0-017 8 0-0313 0-034 7 0-038

6 0-0485 00624 0087

5

10

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(b) Fol lowing observat ions were m a d e for conduct inga wa te r budge t of a reservo i r over a per iod of onem o n t h :Average surface a rea = 10 1un2 , M e a n sur faceinflow ra te = 10 cumec , M e a n surface outflowra te = 15 cumec, Rainfal l = 10 cm, Fal l in th ereservoir level = 15 m , P an evapora t ion = 20 cm..,Assuming the pan-factor as 07,average seepage discharge from.dur ing the month .

es t ima te theth e reservo i r

(c) Design a rec tangula r gr i t c ha m be r for a flow o f40 M L D . Specif ic grav i ty _ 2 65 an d size to beremoved is 02 m.m.Find the(a) se t t l ing veloci ty of 02 mn> part ic les ,(b) cr i t ical hor izonta l velocity of flow, and(c) size of th e gri t chamber .Assume kinemat ic viscosity of th e l iquid -

10 x 10-2 cm 2 /s.(d) Different ia te be tween th e following t e rm s : .

(i) TiIne :mean speed and Space :mean speed(ii) W et dock and D ry dock(iii) S t o p w a y a n d Clea rway of runwa y l eng th(iv) Hydrophi l ic aggrega tes an d Hydrophobic

aggrega tes(v) Base tunne l and Saddle t unne l

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10

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_._ _ .

4. (a ) A pipe network in th e form of a t r i ang le A B C h asinf lows of 5 In3 /s and 4 In3/s a t A an d Brespect ively. T he . outflow a t C is 9 m 3 /s . GivenKAB = 10 , K BC = 50 and KAC = 20 , cOInputedischarges in each pipel ine [h f = KQ2]. . 10

(b) A 120'0 m long s torm sewer collects was tewa te rfrom. a c a tc hm e n t area of 50 hectare , w h e r e 35%area i s covered by roof (I - 0 '9), 20% a rea iscovered by pavElInents (I = 08) and. 45% area iscovered by open l and (I - 0 '13 ). Deter In ine th eaverage I, and diamete r of storIn sewer l ineas s uming(i) th e t ime of en t ry = 3 m in( j i ) veloci ty of full flow = 1 50 m ls( i j i ) n = 0 013 an d s lope =. 0 '001

1 = runof f rat io.(c) A re ta in ing wal l 10 m high i s proposed to hold

dry s and of voic:!.- ra t io of 06 . T he value of angle ofin te rna l friction cp = 30 an d specif ic-gravi ty ofsoil gra in is 2 7 . T he back face of wal l is vert ica lan d smooth . Top sur face of backfil l is hor izontal .Calcu la te the magni tude of the to ta l act ive ea r tht h r u s t aga ins t the wal l assuming th e wall i s freeto move. Also show the d is t r ibu t ion of ea r thpressure and poin t of appl icat ion of th e r e su l t an t .

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A s s u m e u n i t weight o f wa te r = 10 kN/rn3 . 10(d ) ( i )

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W h a t a re th e assumed condi t ions ofrunwa y length for s t anda rd e nv i ronm e n twhich decide th e basic runwa y l e n g t h ?

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(ii) D etenn ine the ac tua l runway l eng th af te rapply ing necessary correct ions for e levat ionan d t empera tu re as pe r l eAO and g rad ien tcorrect ion a s p er FAA specif ication for th eda ta given below. 5+5

Basic runway lengthEleva t ion of Airpor tsiteMonth ly m e a n o faverage dailyt empera tu re forthe ho t tes t TTlonthof the yea rM onthly n lean ofnlaximuTTl dailyt en lpera ture for th esa me TTlonthEffective grad ien t

- 1800 met res

- 60 0 met res

_ 15 C

_ 21 '6 C- 0 6%

. (a) D ra w ind ica tor d iagram for th e fol lowing cases o fa rec iprocat ing p u m p :(i) Wh en no a ir vessel is ins ta l led.(ii) Wh en a ir vessel is ins tal led on suct ion s ide

close to th e pUTTlp.(iii) W h e n a ir vessel is insta l led on del ivery

. s ide close to th e pump.(iv) WheT). a i r vessels are insta l led on boths ides of Un; p u m p .

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(b) H ow m a n y days would be required by a clays t ra tum 5 m thick, dra ining a t both e nds withcoefficient of consol idat ion = 50 x 10- 4 cm 2 /sec toa t ta in 50% of i t s u l t imate se t t l emen t?G i v e n : T50 = 0197. 1

(c) Detenn ine t he length of t rans i t ion curve an doffsets a t every 15 m e t re s fo r B.G. curvedt r ack having 4 curva ture an d can t of 12 cm .T he m a xim um permissible speed on curve i s85 k m p h . . 1

(d) W ater emerges from a spi l lway with a velocity of15 rnlsec and a depth o f 0 5 m . Calcu la te th enecessary subcr i t ical depth a t th e toe of th espi l lway for th e occurrence of a hydraul ic j u m p .Calcula te th e associated energy loss . 1

6 . (a) Why is ver t ica l s ha f t necessary in case of longt u n n e l ?A circular tunne l o f 3 metres d iame te r and3 ki lometres long is to be driven by full faceexcavat ion. The proposed tunne l a l ignment isp a s s i n g t h rough rock. T he ra te o f excavat ion p erblas t is 5 metres . Calcula te th e n u m b e r o fhau l ing t rucks required for mu cking opera tionfrom th e da ta given below. 1

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Capaci ty o f haul ing t ruckAverage haul ing andre tu rn speed of hau l ingt ruckAverage haul ing dis tance

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= 10 tonnes

- 25 k m p h_ 3 k m

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Dens i ty of m u c k% swel l% over-breakingOpera t ing efficiency ofhau l ing t ruckLoading t ime , dumpingt ime , accelerat ion anddecelerat ion t ime etc.

_ 1600 kg/m 3- 15- 5- 75%

= 4 6 mi n u t e s(b) A Pel ton whee l is produc ing 300 kW work ing

u n d e r a head of 180 0 m with discharge o f0 2 m 3/s. Compute hydraul ic efficiency an dvelocity o f whir l a t in le t and out le t and th e m e a nbucke t speed . Take coefficient of velocity = 0 '985,angle of deflection of je t = 165" a n d relat ivevelocity a t exi t = relat ive velocity a t in le t .

(c) The o rd ina tes o f 6 h o u r un i t hydrograph o f aca tchment a re as follows.

Ti m e (hours) Discharge (m3/sec)0 0

6 1012 4018 5524 4530 3036 742 0

10

9 [Contd . )

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7.

Th e u n i t dep th of th e un i t hydrograph is 1 cm.Arrive a t th e direc t runoff hydrograph resul t ingfrom th e follow.ing ,excess-rainfall hyetographoccurr ing over the ca tchment.

Dura t ion (hours )0-66 - 1 2

Rainfal l i n t ens i ty (cmlhr )1

05(d) A 2 tn wide st r ip footing ,i s located a t a dep th o f

2 m in Ii s t i f f clay o f sa tu r a t ed un i t weigh t of20 kN/ tn 2 an d hav ing u = 0 an d C u = 120 kN/Il l 2 U s in g Terzaghi ' s bear ing capaci ty equat ion ,compu te th e safe load car r ied by foot ing p erIlletre l eng th wi th factor of safe ty = 3 with

1

respec t to s h e a r fai lure. G i v e n : Nc = 57 .(a ) ( i )

(ii)

H ow a re fol lowing bi tuI l lenclass i f ied?

Pene t ra t ion g rade Bi tumenBlown b i t u me nCut-backsEmuls ions

b inder s

Exp la in briefly construct ionqual i ty control me a su re sbi tu tn inous macadaIn (DBM).

procedure a n dfor dense

(b) Draw a n d discuss the single s tack sys tem of5

plmnbing .(c) (i) W h a t is '"'negative skin. friction" a n d i t ss ignif icance In th e design of pi le

founda t ion?(ii) Descr ibe 'd i fferent ial free swel l ' t es t of soil .

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(d) T h e following a re th e observed values of a n anglea n d the i r weightage

Angle Weightage30 24 ' 20" , 230 24 ' 18" 230 24 ' 19" 3

Find( i) Probable er ror o f s ingle observat ion o f u n i t

weight .(Ii) Probable e r ro r of weighted a r i thmet i c

tneao .(iii) P ~ o b a b l e e r ro r o f single observa t ion o f

weigh t 3. 10

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Engg Services Civil Engineering Subjective Paper 2 2009