UPSC Civil Engineering 2022 — Paper II

(a) (i) Briefly explain the deterioration of concrete caused by leaching action, and (ii) chemical interaction. (10 marks) (b) What are the general precautions to be observed while constructing a brick masonry work? Briefly explain with the help of neat sketches where possible. (10 marks) (c) A cement concrete pavement of thickness 20 cm, has two lanes of 7·2 m with a longitudinal joint. Design the tie bar. Assume allowable working stress in tension for steel as 1400 kg/cm² and bond strength with concrete as 18 kg/cm². (10 marks) (d) What would be the gradient for a M.G. track when a grade resistance together with curve resistance due to a curve of 6° shall be equal to the resistance due to ruling gradient of 1 in 200? (10 marks) (e) What do you understand by orientation of Plane table? Discuss various methods of orienting the Plane table. (10 marks)

(a) A construction company is planning to purchase an excavation equipment for operating a borrow soil pit that will last 5 years. The soil can be excavated by equipment 'A' or equipment 'B'. Equipment 'A' has an initial cost of ₹ 1·32 lakh and will have no salvage value at the end of the project. Equipment 'B' has an initial cost of ₹ 0·21 lakh. However, to provide the same capacity, 2 numbers of equipment 'B' are required and their operating cost per year together (for 2 numbers of equipment 'B') will be ₹ 0·18 lakh more than the equipment 'A'. Normal service life for equipment 'B' is 3 years with zero salvage value but a 2-year-old equipment 'B' can likely be sold for ₹ 0·05 lakh. If the interest rate is 15%, which equipment (equipment 'A' or 2 numbers of equipment 'B') should be preferred to purchase from the present worth point of view? The estimated salvage value for equipment 'B' must be included as a cash inflow at the end of year 5. (15 marks) (b) Design a flexible pavement for a two-lane undivided carriageway using the following data: Subgrade CBR value = 8%, Lane distribution factor = 0·5, Design Life = 15 years, Planning and Construction period = 1·5 years. Present commercial traffic is as under: Bus (Gross Wt. 15T, 200 vehicles/day, Front Axle – Single, Rear Axle – Dual, Growth Rate 4%), Truck (Gross Wt. 20T, 1512 vehicles/day, Front Axle – Single, Rear Axle – Tandem, Growth Rate 8%). As per IRC 37, 2018 the following pavement composition is desired for CBR of 8% subgrade corresponding to different Design traffic: Design traffic (msa): BC / DBM / WMM / GSB (mm) — 5: 30/50/250/150, 10: 30/60/250/200, 20: 30/90/250/200, 30: 40/95/250/200, 40: 40/105/250/200, 50: 40/115/250/200. (20 marks) (c) The following data were obtained from the spot speed study carried out at a city road. Suggest (i) Speed limit for regulation, (ii) Speed to check geometric design elements, (iii) Lower speed group causing congestion. Speed range (km/h): number of vehicles — 0–10: 0, 10–20: 11, 20–30: 30, 30–40: 105, 40–50: 233, 50–60: 216, 60–65: 68, 65–70: 24, 70–75: 10, >75: 6. (15 marks)

(a) A two-lane State Highway in plain terrain, with cutting section having camber of 2·0%, negotiates a curve of radius 480 m. Design superelevation and explain the process of attaining designed superelevation with the help of neat sketches. 15 marks (b) (i) The following consecutive readings were observed, on a continuously sloping ground, with the help of a 4·0 m staff and a dumpy level. If the reduced level of first point is 99·000 m, calculate the level of last point by entering the readings in level book. Also apply the usual checks. 10 marks 3·815, 2·500, 1·335, 2·980 and 0·800 m (ii) The maximum quantity of water to be discharged by the side drains on both sides of a highway section is 1·8 m³/s. Design rectangular side drains for the following conditions. Both drains carry equal discharge. Maximum permissible velocity of flow = 0·8 m/s Roughness coefficient = 0·03 10 marks (c) The project of constructing a small road in a rural area consists of various activities as given in the table below. The time (in weeks) and cost (₹ in lakh) required for completion of each activity is also given. | Activity | Normal Time (Weeks) | Normal Cost (₹ in lakh) | |----------|---------------------|-------------------------| | 1-3 | 9 | 90 | | 1-2 | 12 | 180 | | 2-3 | 18 | 210 | | 3-4 | 20 | 360 | The construction of road started from 1st January. The project was reviewed after 13 weeks and the following conditions were observed: (i) Activities 1 – 2 and 1 – 3 are completed as originally planned. (ii) Activity 2 – 3 is in process and will require 19 more weeks to complete. (iii) Activity 3 – 4 has not started. Based on the above review after 13 weeks, formulate a new project including all activities. Will the project be completed by 15th August of the same year? If the project is to be completed in 49 weeks, determine how much activity 3 – 4 is to be crashed and what will be the increase in project cost? Assume crash cost for activity 3 – 4 is ₹ 450 lakh and crash time is 17 weeks. 15 marks

(a) In a layout of B.G. Yard, an 8° curve branches off from a 4° main curve in an opposite direction. If speed is restricted to 28·90 km/hr and permissible value of cant deficiency is 7·61 cm, determine the speed restriction on the main line. 15 marks (b) (i) Differentiate between overburnt and underburnt bricks. Why are these bricks not recommended for construction works? 5 marks (ii) List the general factors governing the selection of stone for construction purposes. What considerations would guide in selecting stone for the following use: (I) Face work of a building, and (II) Buildings facing the sea? 10 marks (c) (i) Sketch a cross-section of a masonry wall and show coping, cornice, lintel, jamb and parapet wall in the sketch. Also briefly explain the use of the above parts of a building. 10 marks (ii) Explain the terms eaves, eaves board, common rafters and tie beam with the help of a sketch of cross-section of a slopy roof. Also explain the purpose of tie beam. 10 marks

(a) A catchment has six rain gauge stations. In a year, the annual rainfall recorded by the rain gauges are as follows: | Station | A | B | C | D | E | F | |---------|---|---|---|---|---|---| | Rainfall (cm) | 90 | 100 | 200 | 130 | 120 | 150 | Determine: (i) The standard error in the estimation of mean rainfall in the existing set of rain gauges. (ii) Optimum number of rain gauges in the catchment for 22% error and 5% error. (10 marks) (b) In a confined aquifer whose thickness is 40 m, a well is fully penetrated. Under steady state condition, it is pumped with a constant discharge of 0·04 m³/s. The drawdowns observed at two wells located at 20 m and 200 m from the well are 3·5 m and 0·5 m respectively. Determine the transmissibility and permeability of the aquifer. (10 marks) (c) With the help of a neat sketch, explain the effect of frequency of irrigation on average moisture content, field capacity and permanent wilting point. During a particular stage of crop growth, consumptive use of water is 3 mm/day. Determine frequency of irrigation and depth of water to be applied if the amount of water available in the soil is 50% and root zone depth is 100 mm. Assume irrigation efficiency to be 80%. (10 marks) (d) Determine the UBOD and BOD₅ (in mg/L) of a mixture of 100 mg/L glutamic acid (C₅H₁₀N₂O₃) and 100 mg/L glucose (C₆H₁₂O₆). Assume the value of the BOD₅ first order reaction rate constant as 0·23/d (base 'e'). (10 marks) (e) A multiple tube fermentation test of a river water sample gives the following results: | Serial dilution | 1·0 | 0·1 | 0·01 | 0·001 | 0·0001 | |-----------------|-----|-----|------|-------|--------| | Number of positives | 5 | 5 | 3 | 2 | 0 | The standard values for MPN or coliforms per 100 mL of sample are given below: Number of positive tubes | 10 mL | 1 mL | 0·1 mL | MPN | |-------|------|--------|-----| | 5 | 5 | 3 | 920 | | 5 | 3 | 2 | 140 | | 3 | 2 | 0 | 14 | What is the MPN for the river water sample? (10 marks)

(a) (i) Define unit hydrograph. Explain two basic assumptions made in the derivation of a unit hydrograph. What are the applications and limitations of unit hydrograph? (10 marks) (ii) Given the ordinates of a 4 hr unit hydrograph as below, derive the ordinates of a 12 hr unit hydrograph by using the method of superposition. | Time (h) | Ordinate of 4 hr UH (m³/s) | |----------|---------------------------| | 0 | 0 | | 4 | 30 | | 8 | 120 | | 12 | 200 | | 16 | 250 | | 20 | 210 | | 24 | 130 | | 28 | 75 | | 32 | 50 | | 36 | 20 | | 40 | 10 | | 44 | 0 | (Only derive the ordinates. Do not plot the graph.) (10 marks) (b) (i) Considering the Indian conditions, is a separate system of sewerage a better choice than the combined system? Justify your answer. (10 marks) (ii) What is break point chlorination test? Why is it needed? (5 marks) (c) A city of 1 lakh population is supplied 150 lpcd of water. Assuming 80% of this emerging as wastewater, calculate the volume of a secondary reactor. The influent to the reactor has a BOD₅ of 150 mg/L. It is desired to have an effluent BOD₅ of 5 mg/L, an MLVSS of 3000 mg/L and an underflow concentration of 10,000 mg/L. Use the following constants: Y = 0·5 kg MLVSS/kg BOD₅ kₐ = 0·05 per day Take MCRT of 10 days and HRT of 4 hours. What is the volume and mass flow of sludge waste per day? (15 marks)

(a) (i) Determine the volume of sludge before and after digestion and percent reduction for 500 kg of primary sludge with 5% solids, 55% volatile solids and specific gravity of 1.01. The digested sludge has 10% solids, 90% reduction in original volatile solids and specific gravity of 1.04. (10 marks) (ii) A rapid sand filter unit is to be provided for a city of 2,00,000 persons with water demand of 150 lpcd. The design loading rate to the filter is 200 m³/d.m². Determine the filter surface area for four filters. If the design loading rate is to be met with one filter out of service, what should be the surface area per filter? (10 marks) (b) Draw a Flow Mass Curve and explain how this will be useful in the estimation of the storage capacity of the reservoir for a constant demand. (15 marks) (c) Explain different modes of failure of a gravity dam with neat sketches and equations associated with different modes of failure. (15 marks)

(a) (i) The Gross Command Area for a distributary is 15000 hectares, 80% of which can be irrigated. The intensity of irrigation for Rabi season is 60% and that for Kharif season is 30%. If the average duty at the head of the distributary is 2500 ha/cumec for Rabi season and 1500 ha/cumec for Kharif season, determine the discharge required at the head of the distributary. (10 marks) (ii) Explain Lacey's Regime Theory. Define Initial Regime and Final Regime. Compare the Lacey's Regime Theory with Kennedy's Theory with respect to the design of alluvial channels. (10 marks) (b) What is leachate? What problems may it create if left unmanaged in a solid waste landfill? Explain how the leachate is managed in sanitary landfills. (15 marks) (c) Explain the purpose and procedure for the following stages in EIA process : (i) Screening (ii) Scoping (iii) Public consultation (15 marks)