Civil Engineering UPSC PYQ 2023

A strip footing of width 2.8 m as shown in the figure is founded at a depth of 2.5 m below the ground surface in a C – φ soil. Water table is at a depth of 6 m below the ground surface. The average moist weight of soil above the water table is 18 kN/m³. Determine the ultimate bearing capacity, net ultimate bearing capacity, net allowable bearing pressure and the load per metre for a factor of safety of 2.5. Use the general shear failure theory of Terzaghi. Given : For φ = 30°, N_c = 37.2, N_q = 22.5, N_γ = 19.7 What will be the percent decrease in ultimate bearing capacity if, during flooding, the water level rises 2 m above ground surface? <!--qid:MAINS_2023_Civil_Engineering-I_Q3-->

3.(a) (i) Explain any two traffic surveys carried out to decide the geometric design features of a road. (ii) The relationship between speed and density for a given section of road was found to be v = 100 – 1.2 k, where v is speed in km h⁻¹ and k is density in vehicles km⁻¹. Calculate the speed and density at which maximum flow will occur. Also draw the speed-density, speed-flow and flow-density diagrams indicating the critical values. 3.(b) Starting from ground point A having elevation 100·500 m, levels from points B to F were taken inside a tunnel keeping the staff inverted. The above-staff readings observed are given in the table below. Calculate the levels of all the points marked inside the tunnel and apply the usual checks for calculations. (Complete staff readings table as provided.) 3.(c) Explain in brief (with neat sketches) the phenomenon of bulking of sand. How does bulking of sand affect the concrete mix? <!--qid:MAINS_2023_Civil_Engineering-II_Q3-->

SECTION 'A' 1.(a) What are the approximate limits of chemical (oxide) composition in hydraulic cement? Also state the function of oxides in brief. 1.(b) (i) Explain with neat sketches, how Work Breakdown Structure can be defined with respect to Construction Project Management. (ii) With an example, explain how the work breakdown structure can be classified. 1.(c) What do you understand by workability of concrete? Write the procedure for any one measurement method available to check the workability of concrete. 1.(d) A 100 km length railway line is to be constructed for doubling the existing track. Calculate the quantity of track material required to construct the track. Consider the length of rail as 13 m, density of sleepers as (n + 4) and width of sleeper as 250 mm. 1.(e) The Fore Bearing of side AB of regular hexagonal polygon ABCDEFA in whole circle bearing system is 120°. Find the Fore Bearings and Back Bearings of all the other sides. Also find the bearings of line BE and BF. <!--qid:MAINS_2023_Civil_Engineering-II_Q1-->

4.(a) A machine was purchased for ₹ 4,50,000 on 1st January 2001 and erection and installation cost was ₹ 80,000. The same machine was replaced by a new one on 31st December 2020. If the scrap value was estimated at ₹ 1,50,000: (i) What should be the rate of depreciation fund on 15th June 2010? (ii) If after 12 years of running, some assemblies are replaced and the replacement cost is ₹ 1,50,000, what will be the new rate of depreciation? 4.(b) What is dampness in a building? What are the main causes of dampness and what are the remedies being suggested for making a building damp-proof? 4.(c) A flexible pavement has been designed for two-lane single carriageway of width 7 m with the following data: (i) Commercial vehicles per day in each direction = 750 (as on 31-03-2018) (ii) Date of completion of construction = 31-03-2020 (iii) Rate of traffic growth = 10 % per annum (iv) Design life = 10 years (v) Vehicle damage factor = 2.0 (vi) Lane distribution factor (LDF) for 2-lane single carriageway road = 0.75 (vii) LDF for 4-lane dual carriageway road = 0.75 in each direction Due to some issues, starting of construction got delayed and work actually started on 01-04-2023. In the meantime, the government decided to develop the road as a four-lane dual carriageway. Considering the same design data as planned earlier, calculate the new design life of the project. Assume any additional data required for the design suitably.3c:["$", <!--qid:MAINS_2023_Civil_Engineering-II_Q4-->

Q1. Answer all FIVE sub-parts: (a) An aluminium tensile specimen has a diameter of 30·50 mm and a gauge length of 275 mm. If a force of 17·50 × 10⁴ N elongates the gauge length by 1·28 mm, determine the Poisson’s ratio and the modulus of elasticity. Also, determine by how much the force contracts the diameter of the specimen. Assume shear modulus G = 22 GPa and yield strength σy = 435 N/mm². (b) A solid steel shaft of diameter 65 mm is to be designed using an allowable shear stress τallow = 60 N/mm² and an allowable angle of twist per metre θ = 1°05′. Determine the maximum permissible torque that may be applied to the shaft. Take shear modulus as 80 GPa. (c) In the figure shown below, a strong-box of mass 85 kg rests on a floor. The static coefficient of friction for the contact surface is 0·25. What is the largest force, F, and the highest position, h, for applying this force such that the strong-box will neither slip on the floor nor tip over? (d) As shown in the figure, a beam of symmetrical I-section spanning 8·0 m is prestressed by a parabolic cable with an eccentricity of 150 mm at mid-span and zero at supports. The beam supports a uniformly distributed live load of 2·5 kN/m. (i) Find the effective force in the cable that will balance the dead and live loads on the beam. (ii) Calculate the shift of the pressure line from the tendon’s centre-line. Take the unit weight of concrete as 24 kN/m³. (e) A tie member consisting of an ISA 75 × 50 × 8 angle (E-250 grade steel) is connected to a 12 mm thick gusset plate by a 6 mm fillet weld made in situ on three sides, as shown in the figure. The angle between fusion faces is 75°. Determine the lengths of weld Lw₁ and Lw₂ if the connection is to transmit a load equal to the design strength of the member. For ISA 75 × 50 × 8 : Ag = 938 mm² and Cxx = 25·2 mm. Take γm0 = 1·10; for site welding γmw = 1·5; K = 0·7 for 60°–90° angle between fusion faces. For E-250 grade steel: fu = 410 MPa, fy = 250 MPa.2a:["$","section","2023",{"className":"mb- <!--qid:MAINS_2023_Civil_Engineering-I_Q1-->

2.(a) For a project consisting of several activities, the allotted time and the dependencies of the activities are presented below: Activity Duration (days) Pre-decessor P 5 – Q 4 – R 6 Q S 5 P T 7 P U 4 T, R (i) Prepare a network and mark critical path in it. (ii) Calculate Float, Earliest start, Earliest finish, Latest start and Latest finish times. 2.(b) Trains of different speeds are to be run on a 2° curve on a broad gauge. The average speed of trains to be run on the track is 80 kmph. Calculate the value of equilibrium cant. Also calculate the maximum permissible speed on the track allowing the maximum cant deficiency. 2.(c) (i) An aircraft flew at the altitude of 5000 m above the mean sea level. Two consecutive photographs were taken with the camera of focal length 300 mm on the flat ground having elevation of 2000 m above mean sea level. The longitudinal overlap is 65 % and photograph print size is 300 mm × 300 mm. Calculate the scale of the photograph and distance between the two consecutive exposure stations. (ii) What is spectral reflectance curve? Explain its significance in Remote Sensing.39:["$ <!--qid:MAINS_2023_Civil_Engineering-II_Q2-->

Q2. Answer both sub-parts: (a) Draw the shearing force and bending moment diagrams for the beam loaded as shown in the figure. (b) As per the limit-state method, a simply supported ISMB 550 @ 1·037 kN/m of 7 m effective span is required to carry a uniformly distributed load from a concrete slab, a central dead load of 100 kN, an additional live load of 150 kN, and its own distributed self-weight of 50 kN. Check the beam for (i) shear capacity, (ii) bending capacity, (iii) deflection, and (iv) bearing and web buckling at supports, using the data provided (fy = 250 MPa, E = 2 × 10⁵ MPa, γm0 = 1·1, βb = 1·0, ψ = 1·2, table of fcd values, etc.). <!--qid:MAINS_2023_Civil_Engineering-I_Q2-->