UPSC Civil Engineering 2023 — Paper II

This multi-part question requires explaining theoretical concepts in (a), (b), (c), solving numerical problems in (d) and (e). Allocate approximately 15-18 minutes per 10-mark sub-part: spend ~15% time on (a) cement chemistry, ~20% on (b) WBS with sketches, ~15% on (c) workability procedure, ~25% on (d) track material calculations, and ~25% on (e) bearing computations. Begin each part with clear headings, use sketches for (b), show all calculations for (d)-(e), and conclude with practical implications where relevant.

• (a) Chemical composition limits: CaO (60-67%), SiO₂ (17-25%), Al₂O₃ (3-8%), Fe₂O₃ (0.5-6%), MgO (<2%), SO₃ (<3%); functions: CaO for C-S-H formation, SiO₂ for strength, Al₂O₃ for quick setting, Fe₂O₃ for color and flux
• (b)(i) WBS definition: hierarchical decomposition of project deliverables into manageable work packages; sketch showing Level 1 (Project) → Level 2 (Major deliverables) → Level 3 (Work packages) → Level 4 (Activities)
• (b)(ii) WBS classification: by phase (planning, design, construction, commissioning), by system (structural, MEP, finishes), by geography (zone-wise), or by organizational unit; example: Metro Rail Project WBS
• (c) Workability definition: ease with which concrete can be mixed, transported, placed, compacted and finished without segregation; Slump Test procedure: cone filling in 3 layers with 25 tamps each, lifting cone vertically, measuring subsidence
• (d) Track material calculations: number of rails = (100,000 × 2)/13 = 15,385 rails; sleepers = (100,000/0.6) × 2 = 333,333 sleepers (assuming n=6, spacing 60cm); ballast volume ≈ 1,00,000 m³; fastenings, fish plates
• (e) Bearing calculations: hexagon internal angle = 120°, FB of BC = 120° + 60° = 180°, CD = 240°, DE = 300°, EF = 0°/360°, FA = 60°; BB = FB ± 180°; BE bearing = 300°, BF bearing = 0°

Solve all five sub-parts systematically, allocating time proportionally to marks: spend ~40% on part (a) network analysis (20 marks), ~30% on part (b) railway cant calculations (15 marks), ~20% on part (c)(i) photogrammetry (5 marks), and ~10% on part (c)(ii) spectral reflectance theory (10 marks). Begin with clear problem identification, show all calculations with proper units, draw neat diagrams for (a)(i) and label critical path distinctly, and conclude with practical implications for each engineering application.

• For (a)(i): Construct correct AOA or AON network with proper node numbering and activity arrows; identify critical path as Q-R-U (14 days) or equivalent based on correct forward/backward pass
• For (a)(ii): Calculate ES, EF, LS, LF for all activities and determine total float (TF = LS-ES or LF-EF) and free float correctly; show tabular presentation
• For (b): Calculate equilibrium cant using e = GV²/127R (or e = 0.0007V²/R for BG) with V=80 kmph, R=875m (from 2° curve); calculate cant deficiency using IRC limit of 75mm for BG and find maximum permissible speed
• For (c)(i): Calculate scale as f/(H-h) = 300mm/(5000-2000)m = 1:10,000; compute ground coverage and exposure station spacing using 65% overlap formula
• For (c)(ii): Define spectral reflectance curve as plot of reflectance vs wavelength; explain significance for land cover classification, vegetation health monitoring, and band selection in Indian remote sensing applications (IRS/LANDSAT)

This multi-part question requires solving numerical problems in (a)(ii) and (b) while explaining concepts in (a)(i) and (c). Allocate approximately 35% time to (a)(ii) for its 15 marks involving traffic flow calculations and three diagrams, 30% to (b) for the 15-mark levelling problem with inverted staff, 20% to (c) for the 15-mark bulking explanation with sketches, and 15% to (a)(i) for the 5-mark traffic survey description. Begin with clear statements of given data, show all formulae and substitutions, and conclude with practical implications.

• (a)(i): Identification and explanation of any two relevant traffic surveys (e.g., speed and delay study, origin-destination survey, traffic volume study, spot speed study) with their specific application to geometric design
• (a)(ii): Derivation of q = vk, calculation of optimum speed v₀ = vₘ/₂ = 50 kmph, optimum density k₀ = kⱼ/₂ = 41.67 veh/km, and maximum flow qₘₐₓ = vₘkⱼ/₄ = 2083.33 veh/hr using v = 100 - 1.2k
• (a)(ii): Correct plotting of three fundamental diagrams (speed-density, speed-flow, flow-density) with proper axes, curves, and critical values marked (vₘ, kⱼ, qₘₐₓ, v₀, k₀)
• (b): Application of inverted staff correction (reading subtracted from height of instrument), correct calculation of HI at each setup, and computation of levels for points B through F with proper sign convention
• (b): Application of arithmetic check (ΣBS - ΣFS = Last RL - First RL) and closure check for the levelling operation
• (c): Explanation of bulking phenomenon due to surface moisture forming films around sand particles, increase in volume by 20-40% at 5-8% moisture content, and peak bulking at 4-6% moisture
• (c): Neat sketches showing dry sand, moist sand with water films causing particle separation, and fully saturated sand where bulking disappears
• (c): Effects on concrete mix: reduced strength if volume batching used without correction, need for weight batching or bulking factor adjustment, and field practices in Indian construction sites

This is a multi-part calculation-based question requiring precise numerical work across depreciation accounting, building science, and pavement engineering. Allocate approximately 40% time/effort to part (a) given its 20 marks weightage, 30% to part (b) for 15 marks, and 30% to part (c) for 15 marks. Begin with clear identification of given data, show all formulas with standard notations (IRC:37 for pavement, IS 1893/standard depreciation methods), present step-by-step calculations with proper units, and conclude with practical interpretations of results.

• Part (a)(i): Calculate depreciation rate using sinking fund method or straight line method for period 1.1.2001 to 15.6.2010 (9.5 years), considering total first cost ₹5,30,000 and scrap value ₹1,50,000
• Part (a)(ii): Recalculate depreciation rate after capital addition of ₹1,50,000 at year 12, adjusting book value and remaining useful life till 31.12.2020
• Part (b): Define dampness as unwanted moisture intrusion; enumerate causes (capillary action, rain penetration, condensation, ground water); describe remedies (DPC at plinth, waterproof plaster, surface treatments, proper drainage)
• Part (c): Calculate cumulative standard axles (MSA) for original 2-lane design using N = 365×A×[(1+r)^n-1]/r × VDF × LDF with A=750, r=0.10, n=10
• Part (c) continued: Recalculate design life for 4-lane dual carriageway using same total MSA but revised LDF=0.75 each direction (effectively 0.375 per lane), solving for new n when traffic starts 1.4.2023 with updated base year CVPD

This is a multi-part numerical question requiring precise calculations across hydrology and water quality. Begin with part (a) by constructing the storm hydrograph using φ-index and base flow separation, allocating approximately 25% time. For part (b), compute weighted averages for precipitation and evaporation using area-weighting, then derive runoff coefficients—allocate 20% time. Part (c) demands Muskingham routing with given x and K values; set up the routing equation systematically—20% time. Part (d) requires concise but comprehensive explanations of five water quality parameters with their health/ecological significance—20% time. Conclude with part (e) applying Stokes' law for settling velocity and checking against scour velocity—15% time. Present all calculations in tabular format where possible.

• Part (a): Correct application of φ-index (0.3 cm/hr) to determine effective rainfall, convolution with 6-hour UH ordinates, and addition of base flow (25 m³/s) to obtain total storm hydrograph ordinates
• Part (b): Area-weighted calculation of annual average precipitation and evaporation for the catchment; computation of runoff coefficients for sub-areas P, Q, R, S using water balance equation (P - E = R), and overall catchment runoff coefficient
• Part (c): Application of Muskingham routing equation with x = 0.25, K = 8 hr, initial outflow = 10 m³/s; correct determination of routing coefficients C₀, C₁, C₂ and computation of outflow hydrograph ordinates
• Part (d): Explanation of nitrites (toxicity, methemoglobinemia), nitrates (eutrophication, drinking water limit 45 mg/L), E-coli (fecal contamination indicator), BOD (organic pollution load, deoxygenation), and dissolved oxygen (aquatic life support, minimum 4-5 mg/L for warm-water fish)
• Part (e): Calculation of settling velocity using Stokes' law for 0.03 mm particles at 25°C (v = 0.01 cm²/s, G = 2.65), verification of Reynolds number < 1 for Stokes' validity, and determination of flow velocity ensuring detention time allows particle removal (L/v_flow = H/v_settling)

Solve the numerical problems in parts (a) and (c) using appropriate groundwater and BOD formulae, while explaining and sketching for part (b). Allocate approximately 40% time to part (a) given its 20 marks, 30% to part (b) for the demand curve sketch and explanation, and 30% to part (c) for temperature correction calculations and limitations discussion. Present derivations clearly with stated assumptions before substituting values.

• Part (a)(i): Apply Dupuit-Thiem equation for unconfined aquifer to find discharge at 6m drawdown, recognizing that transmissibility remains constant and discharge is proportional to (2H-s)s
• Part (a)(ii): Calculate discharge for 30cm well using same aquifer properties, applying well radius scaling in the logarithmic term of Dupuit equation
• Part (b): Explain peak hour factor (typically 1.5-2.5 for Indian cities) and its impact on distribution main sizing, service reservoir capacity, and pumping station design
• Part (b): Sketch typical Indian diurnal demand curve showing morning and evening peaks, with minimum night flow and seasonal variation for summer/winter
• Part (c)(i): Apply temperature correction formula K_T = K_20 × φ^(T-20) to find K_25, then use BOD_t = L_0(1-e^(-Kt)) relationship to find ultimate BOD and 5-day 20°C BOD
• Part (c)(ii): Enumerate BOD limitations: 5-day delay in results, inhibition by toxic substances, nitrification interference, dilution requirements, and non-representative of actual stream conditions

The directive 'discuss' in part (a) demands critical examination with causes, effects and remedies; parts (b) and (c) require 'explain' and 'define/derive' respectively. Allocate approximately 40% time/words to part (a) given its 20 marks weightage, 30% to part (b) for 15 marks, and 30% to part (c) for 15 marks. Structure: brief introduction on activated sludge process relevance → systematic treatment of each sub-part with definitions, mechanisms, impacts/diagrams → concluding synthesis on operational challenges in Indian STPs.

• Part (a)(i): Rising/floating sludge — denitrification mechanism (NO₃⁻ → N₂ gas bubbles), sludge density reduction, identification by sludge volume index, remedies like increasing sludge wasting or reducing MLSS
• Part (a)(ii): Sludge bulking — filamentous bacteria (Sphaerotilus, Thiothrix) vs. floc-forming bacteria competition, low DO/high F/M ratio causes, SVI>150 mL/g indicator, control by chlorination or selector basins
• Part (b): Specific capacity (Q/s, m³/day/m), specific yield (Sy = ΔV/Δh·A, dimensionless), perched water table (localized saturated zone above main aquitard), intrinsic permeability (k, m², fluid-independent), bulk pore velocity (v = K·i/n, actual interstitial velocity)
• Part (c)(i): Delta (Δ, depth of water required), Duty (D, area irrigated per cumec), Base Period (B, crop duration); derivation: Δ = 8.64·B/D in cm, with unit consistency demonstration
• Part (c)(ii): Dam site factors — narrow gorge with wide upstream valley, sound foundation rock, adequate catchment, sediment-free water, proximity to demand, seismic stability, environmental/social acceptability (cite Tehri or Sardar Sarovar context)

The directive 'design' in part (a)(i) demands a complete hydraulic design with numerical solution, while other parts require descriptive and explanatory responses. Allocate approximately 25% time to (a)(i) for rigorous Manning's equation application with B/D=5 constraint, 20% to (a)(ii) for spillway classification and energy dissipators, 25% to (b) for systematic coverage of five pollutants with sources and health effects, and 30% to (c) for landfill site selection criteria and biochemical processes. Structure with clear sub-headings, present calculations in tabular format, and conclude with practical implications for Indian conditions.

• (a)(i) Correct application of Manning's equation with given B/D=5 ratio to solve for normal depth and base width, verification of hydraulic parameters
• (a)(ii) Classification of spillways (ogee, chute, shaft, siphon, side channel) with sketches; energy dissipation methods (hydraulic jump, ski jump, roller buckets) with Indian dam examples like Bhakra or Hirakud
• (b) Systematic presentation of five pollutants: sources (industrial, vehicular, thermal power) and specific health effects (neurotoxicity, nephrotoxicity, carcinogenicity, Minamata disease, CO poisoning)
• (c)(i) Site selection criteria: hydrogeological isolation, distance from water bodies, accessibility, soil permeability, climatic factors, social acceptance referencing CPHEEO/MSW Rules
• (c)(ii) Anaerobic decomposition phases, gas generation (CH₄, CO₂, H₂S), leachate formation chemistry with relevant equations; leachate migration and control measures