Subject 2014 Question Paper — Government College of Engineering and T…

The 2014 Subject previous year question paper (Government College of Engineering and Technology, Jammu), with every question and its marks.

Instructions

Q1. a). A 8m high retaining wall supports a 5.5m deep sand $(\gamma_d = 18.5\text{ kN/m}^3, \varnothing = 34^0)$ overlying a saturated sandy clay $(\gamma_{sat} = 20.3\text{ kN/m}^3, \varnothing=28^0, C=17\text{ kPa})$. The ground water is located at the interface of two layers. Sketch the lateral stress distribution up to a depth of 8m for an active condition. [10 marks]
Qb). Describe the trial wedge theory for determining active earth pressure. discuss the advantages. [10 marks]
Q2. a). At cut 9m deep is to be made in clay with a unit weight of $18\text{ kN/m}^3$ and cohesion of $27\text{ kN/m}^2$. A hard stratum exists at a depth of 18m below the ground surface. Determine from Taylor's charts if a $30^0$ slope is safe. If a factor of safety of 1.50 is desired, what is a safe angle of slope? [10 marks]
Qb). How a slope is analysed using method of slices? Write an expression for factor of safety. [10 marks]

Q3. a). A circular footing is resting on a stiff saturated clay with unconfined compressive strength is $250\text{ kN/m}^2$. The depth of foundation is 2m. Determine the diameter of the footing if the column load is $600\text{ kN}$. Assume a factor of safety as 2.5. The bulk unit weight of soil is $20\text{kN/m}^3$. [10 marks]
Qb). Differentiate between :- General shear failure, Local shear failure & Punching shear failure. [10 marks]
Q4. a). Plate load test data are given below. Plot the load-settlement curve and find the ultimate bearing capacity. Take width of plate is $300\text{mm}$ & least count of dial gauge is $0.01\text{mm}$. Load intensity (kN/m²): 0 | 55 | 110 | 165 | 220 | 280 | 335 Dial Gauge reading A: 0 | 186 | 362 | 766 | 1886 | 4810 | 14006 Dial Gauge reading B: 0 | 192 | 365 | 758 | 1889 | 4806 | 14010 Dial Gauge reading C: 0 | 192 | 353 | 756 | 1865 | 4784 | 13984 [8 marks]
Qb). What is the safe load of a footing laid at a depth of $1.3\text{m}$ below the ground surface under the following condition: i) Size $2\text{m} \times 2\text{m}$, G.W.L. at 8m below natural ground level; and ii) Size $2\text{m} \times 2\text{m}$, G.W.L at $1.5\text{m}$ below natural ground level. The load on the footing acts at an angle of $15^0$ to the vertical. Take $\gamma=20\text{kN/m}^3$, $\gamma_{sat}=21\text{kN/m}^3$ and angle of internal friction of $30^0$.Use Vesic's bearing capacity factors $N_q=18.4$ & $N_c=22.4$. [12 marks]

Q5. a). A $300\text{mm}$ dia concrete pile, $10\text{m}$ long, was driven by double acting hammer (rated energy $16.62\text{kj}$, total mass $2200\text{ kg}$) The driven was done with a short dolly and cushion $2.50\text{m}$. The average penetration recorded in the last five blows was $3\text{mm/blow}$. calculate the safe pile load by Hiley formula. [10 marks]
Qb). What are 'Tilts and Shifts'? What are theremedial measures to control these? [10 marks]
Q6. a). A Cylindrical well of external diameter 6m and internal diameter 4m is sunk to a depth $16\text{m}$ below the maximum scour level in a sand deposit. The well is subjected to a horizontal force of $1000\text{ kN}$ acting at a height of 8m above the scour level. Determine the total allowable equivalent resisting force due to earth pressure, assuming that (a) the well rotates about a point above the base, and (b) the well rotates about the base. Assume $\gamma=10\text{ kN/m}^3$, $\varnothing=30^0$, and factor of safety against passive resistance = 2. Use Terzaghi's Approach. [12 marks]
Qb). A group of nine piles, $10\text{m}$ long is used as a foundation for a bridge pier. The piles used are $30\text{cm}$ dia with c/c spacing $0.9\text{m}$. the subsoil consist of clay with unconfined compressive strength of $1.5\text{ kg/cm}^2$. Determine the efficiency neglecting the bearing action. [8 marks]

Q7. a). A rectangular footing of $5\text{m} \times 2.5\text{m}$ size, carries a uniformly load of intensity $160\text{ kN/m}^2$ and is located at a depth of $1.5\text{m}$ in a layer of clay of $6\text{m}$ thickness and having $E_u\text{ value} = 40,000\text{ kN/m}^2$. This clay layer is underlain by a second clay layer of $8\text{m}$ thickness and having $E_u = 70,000\text{ kN/m}^2$. A hard stratum lies below the second layer. Calculate the average immediate settlement under the footing. [10 marks]
Qb). Sketch a split-spoon sampler and explain its parts. Explain the terms 'Inside clearance' and 'Outside clearance' as applied to a sampler. [10 marks]
Q8. a). An overhead water tank is supported at a depth of 3m by four isolated square footing of sides 2m each placed in a square pattern with ac/c spacing of 8m. Compute the vertical stress at the foundation level. i) at the four footings and ii) at the centre of one footing. The load on the footing is $700\text{ kN}$. Adopt Boussinesq's point load approximation. [12 marks]
Qb). What sort of expertise would be needed to choose the borehole depth and number in a ground investigation? [8 marks]