BPSC Main Exam 2019 ASSISTANT ENGINEER

Transcription

1 DETAILED OLUTION Test Centres: Delhi, Noida, yderabad, Bhopal, Jaipur, Luknow, Bhubaneswar, Indore, Pune, Kolkata, Patna BPC Main Exam 09 AITANT ENGINEER CIVIL ENGINEERING Test Objetive Paper-II ANWER KEY. (b). (). (a) 3. (d) 4. (a). (b). (). () 3. (d) 4. (a) 3. (d) 3. (b) 3. (a) 33. (b) 43. (d) 4. (d) 4. () 4. (b) 34. () 44. (a) 5. (b) 5. (a) 5. (a) 35. () 45. (a) 6. (a) 6. (b) 6. (b) 36. (d) 46. () 7. (b) 7. (a) 7. (b) 37. (b) 47. (a) 8. () 8. (b) 8. (b) 38. (b) 48. (b) 9. () 9. () 9. () 39. (d) 49. (a) 0. (b) 0. () 30. (a) 40. (b) 50. ()

2 DETAILED EXPLANATION. (b) Linings and sound absorbing materials are most ommonly used in theatres, onert arena and movie halls beause they abate refletion noises.. (b) BOD mix Q BOD Q + Q + Q R R BOD R mg/l 3. (d) The sonosope/water phone is reommended by the AWWA (Amerian Water Work Assoiation) standards ommitte in its inspetion and maintainae proedure for hydrants. Its regular use promots leak awareness and identifies ostly leaks. 4. (d) The filtration proess auses bloking of filter media due to impurities arrested in them. The downward flow of water is resisted by sand grains and impurities arrested in them. A stage may reah when the fritional resistane exeeds the stati head of water above the sand bed most of this resistane is aused by the top 0 to 5 m sand layer. The bottom sand ats like a vauum and the water is suked through the filter media without leaning. The dissolved air and gases from water are released and they stik to sand grains. This phenomena is alled air binding and seriously affets the effiieny of filter. 6. (a) BOD to be treated by oxidation pond ppm BOD kg/day 67.5 kg/day Area of the pond ha 7. (b) It is a manner of expressing BOD loading with regard to the mirobial mass in the system. The BOD load applied to the system in kg or gm is represented as food (F), and the total mirobial suspended solids in the mixed liquor of the aeration tank is represented by M. F/M ratio for an ativated sludge plant is the main fator ontrolling BOD removal. Lower the F/M value, the higher will be the BOD removal in the plant. The F/M ratio an be varied by varying the ML onentration in the aeration tank. 8 Civil Engg. (Test-) Copyright : MADE EAY

3 8. () Aerobi onditions are maintained in the upper portions of the faultative pond by oxygen generated by algae, and, to a lesser extent by penetration of atmospheri oxygen. tagnant onditions in the sludge along the bottom prevent oxygen transfer to that region and anaerobi onditions prevail there. The boundary between the aerobi and anaerobi zones is not stationary. Mixing by wind ation and penetration by sunlight may extend the aerobi area downward. Conversely alm waters and weak lighting result in the anaerobi layer rising toward the surfae. 9. () Ferrule: A ferrule is a right angled sleeve made of brass or gun metal, and is joined to a hole drilled in the water main. Goose nek: Goose nek is a small sized urved pipe made of a flexible material (usually lead) forming a flexible onnetion between the water main and the servie pipe. ervie pipe: ervie pipe is a galvanised iron pipe of size less than 50 mm dia. The servie pipe whih supplies water to the building through the muniipal main is thus onneted to the main through the goose nek and ferrule. top ok: The stop ok is provided before the water enters the water meter in the house.. () Design disharge Disharge required in the field Time fator apaity fator umes 3. (b) Average boundary shear stress, τ av 4. () γ w R N/mm ( R y for wide retangular hannel) Laey s sour depth.35 q f /3 q 3 ume f. R /3.64 m 9 Civil Engg. (Test-) Copyright : MADE EAY

4 5. (a) Garret s diagram is graphial solution of Kennedy s and Kutter s equations to save enormous mathematial alulations in the design of irrigation hannels. These have been drawn for trapezoidal hannel with side slopes as : V on the assumption that irrigation hannels adopt approximately this shape even though they were onstruted on different side slopes. 7. (a) Leahing is the proess in whih land is flooded with adequate depth of water. The alkali salts present in soil, get dissolved with this water, whih perolate down to join the water table or are drained away by sub-surfae drains. Dd Leahing requirement, LR Di D d is Depth of water drained out per unit area D i is Depth of irrigation water applied per unit area D i C u + D d C u is Consumptive use LR D C EC i u i Di ECd EC i is Eletrial ondutivity of irrigation water EC d is Eletrial ondutivity of drained water. 9. () Meander length (M L ) is the axial length of one meander, i.e., the tangential distane between the orresponding points of a meander. 0. () Duty at the head of water ourse alled outlet disharge fator.. () B C ene, if B is taken equal to or greater than, no tension will be developed at the heel C with full reservoir. When C B If uplift is not onsidered, B ( C 0) 0 Civil Engg. (Test-) Copyright : MADE EAY

5 For the dam to be safe in sliding B μ ( C) If C, B μ( ) If C 0, i.e., no uplift is onsidered then B μ 5. (a) If the onditions relevant to the reording of a raingauge station have undergone a signifiant hange during the period of reord, inonsisteny would arise in the rainfall data of that station. The heking for inonsisteny of reord is done by the double mass urve tehnique. This tehnique is based on the prinipal that when eah reorded data omes from the same parent population, they are onsistent. 6. (b) A part of rain may be aught by vegetation and subsequently evaporated. The volume of water so aught is alled intereption. Intereption loss is solely due to evaporation and does not inlude transpiration, through fall or stemflow. 7. (b) In shallow stream of depth up to about 3.0 m, the average veloity V V 0.6d This is alled single point observation. In moderately deep streams the veloity is observed at two points. V0.d + V0.8 d V In rivers having large flood flows, only surfae veloity (V s ) is measured within a depth of about 0.5 m from the surfae. The average veloity V kv s where k is in the range of 0.85 to (b) If the bed of the stream is below the groundwater table, during period of low flows in the stream, the water surfae may go down below the general water table elevation and the groundwater ontributes to the flow in the stream suh stream whih reeive groundwater flow are alled effluent stream water perolates to the groundwater storage and a hump is formed in the groundwater table. uh streams whih ontribute to the groundwater are known as influent streams. Civil Engg. (Test-) Copyright : MADE EAY

6 9. () Let the time base B(hours) B B 50 hours 30. (a) The flood that would result from a sever ombination of meteorologial and hydrologial fators that are reasonably appliable to the region. Extremely rare ombinations of fators are exluded. 3. (d) Using equation, N N N N 8 N rpm 0 3. (d) w Free surfae h Fored Vortex A ylinder rotating about the vertial axis has fored vortex flow. The free surfae is paraboloid with half the volume of ylinder of same height when half the liquid spills out and thus entre of the bottom will be exposed to atmosphere and gauge pressure will be zero. Civil Engg. (Test-) Copyright : MADE EAY

7 35. () P P In ase of pump, P N D N D P P m p D D m p 5 5 m 3 P (Given N onstant) 46. () Kjehldahl Nitrogen Organi nitrogen + Free ammonia 49. (a) Tension will not be developed at the heel with full reservoir, when b G K 3 Civil Engg. (Test-) Copyright : MADE EAY