Civil Engineering 2022 Paper II 50 marks Compulsory Design

Q1

(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)

हिंदी में प्रश्न पढ़ें

(a) (i) निषालन क्रिया, तथा (ii) रासायनिक अन्तःक्रिया के द्वारा कंक्रीट के अवक्षय की संक्षेप में व्याख्या कीजिए। (10 अंक) (b) एक ईंट चिनाई कार्य का निर्माण करते समय क्या सामान्य सावधानियाँ बरती जाती हैं? जहाँ सम्भव हो स्वच्छ रेखाचित्रों की सहायता से संक्षेप में व्याख्या कीजिए। (10 अंक) (c) एक 20 cm मोटी सीमेंट कंक्रीट कुशिम में अनुदैर्ध्य जोड़ के साथ 7·2 m की दो लेन हैं। बंधन छड़ का अभिकल्पन कीजिए। इस्पात के लिए तनन में अनुज्ञेय कार्यकारी प्रतिबल 1400 kg/cm² और कंक्रीट के साथ बंधन सामर्थ्य 18 kg/cm² मान लीजिए। (10 अंक) (d) एक एम.जी. रेलपथ के लिए प्रवणता क्या होगी यदि 6° के वक्र के कारण वक्र प्रतिरोध के साथ प्रवणता प्रतिरोध, 200 में 1 की नियंत्रक प्रवणता के कारण प्रतिरोध के बराबर हो? (10 अंक) (e) प्लेन टेबल के अभिविन्यास से आप क्या समझते हैं? प्लेन टेबल के अभिविन्यास करने की विभिन्न विधियों की विवेचना कीजिए। (10 अंक)

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Directive word: Design

This question asks you to design. The directive word signals the depth of analysis expected, the structure of your answer, and the weight of evidence you must bring.

See our UPSC directive words guide for a full breakdown of how to respond to each command word.

How this answer will be evaluated

Approach

This multi-part question requires a balanced approach across theoretical explanations, numerical design, and practical applications. Allocate approximately 20% time to each sub-part: (a) explain leaching and chemical attack mechanisms with examples like sulfate attack in coastal Gujarat; (b) describe brick masonry precautions with sketches showing frog placement and bonding patterns; (c) design tie bars showing complete calculations for spacing and diameter; (d) solve the railway gradient problem using IRC formulas for curve compensation; (e) explain plane table orientation methods with field procedure diagrams. Begin with concise definitions, present numerical parts with clear formulae and substitutions, and conclude with practical implications for Indian construction conditions.

Key points expected

  • (a) Leaching: explains dissolution of Ca(OH)₂ in flowing/pure water, increased permeability, reference to IS 456 limits; Chemical interaction: covers sulfate attack (ettringite formation), chloride-induced corrosion, alkali-aggregate reaction with Indian examples like Thane creek structures
  • (b) Precautions: soaking bricks, proper mortar consistency (1:6 for normal, 1:4 for exposed), English/Flemish bond patterns, frog upward placement, 10-12mm joints, curing; sketches showing queen closer, header-stretcher arrangement
  • (c) Tie bar design: calculates frictional force (WLf/2), steel area required (Aₛ = F/σₛₜ), bond length check (L = F/πdτ_bd), final specification of diameter, spacing, length with IRC:58 provisions
  • (d) Railway gradient: applies curve resistance formula (0.04° for BG, 0.03° for MG), equates grade resistance + curve resistance = ruling gradient resistance, solves for compensated gradient
  • (e) Orientation: defines as making table parallel to ground line; methods—(i) trough compass (magnetic), (ii) back-sighting (geometric), (iii) resection (three-point/Bessel's method); compares accuracy and field conditions for each

Evaluation rubric

DimensionWeightMax marksExcellentAveragePoor
Concept correctness25%12.5Accurately distinguishes leaching (physical dissolution) from chemical attack (sulfate, chloride, AAR); correctly identifies IRC:58 for pavement design and Railway Engineering standards for gradient; explains orientation as geometric alignment problem not just magnetic northMixes up leaching with carbonation; uses generic concrete codes without IRC:58 specifics; states orientation methods by name without explaining geometric principle; minor errors in railway curve resistance formulaConfuses leaching with efflorescence; omits chemical reaction products (ettringite, calcium sulfoaluminate); fundamentally wrong orientation concept; applies BG instead of MG curve resistance values
Numerical accuracy20%10Tie bar: correct frictional force calculation (W=2400 kg/m³, L=7.2m, f=1.5), steel area, bond length verification, final spacing ≤30×thickness; Railway: correct substitution (0.03×6°=0.18% grade resistance), accurate compensated gradient calculation with proper unit conversionCorrect formula but arithmetic errors in final values; omits safety factor in tie bar spacing; railway calculation uses approximate curve resistance values; unit confusion between % and 1 in xWrong formula for frictional force (misses lane factor); calculates tie bar diameter without checking bond length; railway solution adds instead of equating resistances; order-of-magnitude errors
Diagram quality20%10Clear labeled sketches: (b) brick courses showing frog position, queen closer, toothing; (c) tie bar detail at longitudinal joint with dimensions; (e) plane table setup showing alidade, trough compass, orientation by back-sight; neat freehand with construction linesDiagrams present but missing key labels (e.g., frog direction, joint type); tie bar shown without embedment length detail; plane table methods described without visual representation; overcrowded or disproportionate sketchesNo diagrams despite 'neat sketches' instruction; irrelevant diagrams (e.g., general concrete mix); completely wrong representations (e.g., tie bars in transverse joints); illegible or miniature sketches
Step-by-step derivation20%10Systematic presentation: states given data → assumptions → formulae with codes → substitution → calculation → result verification; for tie bar shows force equilibrium, steel design check, bond check, final detailing; railway problem shows resistance balance equation explicitlyCalculations correct but jumps steps; omits code references (IRC:58, Railway Engineering); shows final answer without intermediate values; mixed units without conversion stepsNo derivation shown—only final answers; random numbers without context; wrong formulae stated confidently; calculations scattered across answer without logical flow
Practical interpretation15%7.5Links leaching to porous concrete in Himalayan river structures; connects sulfate attack to Gujarat coastal durability issues; explains why tie bars prevent joint faulting in NHAI highways; relates MG gradient compensation to Nilgiri Mountain Railway operations; specifies when each orientation method suits reconnaissance vs. detailed surveyGeneric statements about durability importance; mentions 'safety' without specific failure mode; standard textbook applications without Indian context; lists orientation methods without selection criteriaNo practical connection made; purely theoretical treatment; irrelevant examples from unrelated fields; dangerous misconceptions (e.g., omitting tie bars acceptable for low traffic)

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