JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III FOUNDATION ENGINEERING Previous Question Paper (February - 2023 - R18)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
What do you understand by Geophysical method of soil exploration?
Answer
Geophysical methods are non-destructive site exploration techniques that measure physical properties of subsurface materials, such as electrical resistivity, seismic wave velocity, or gravitational variations, to infer the stratification and nature of soil and rock layers without direct sampling.
Why should we apply corrections for the N value obtained from the field?
Answer
The N-value obtained from the Standard Penetration Test (SPT) must be corrected for overburden pressure (to account for the increase in soil density with depth) and for dilatancy (in fine sands and silts below the water table) to ensure the value represents the true relative density and strength of the soil, independent of depth and pore pressure effects.
What are the probable types of failure of a slope?
Answer
Sign in to view the complete answer paper.
How is Bishops rigorous analysis different from his simplified method?
Answer
Sign in to view the complete answer paper.
Write a note on stability of retaining walls against sliding.
Answer
Sign in to view the complete answer paper.
What are the stability requirements for retaining wall?
Answer
Sign in to view the complete answer paper.
State the factors affecting location of footing.
Answer
Sign in to view the complete answer paper.
Comment on the statement “The net bearing capacity of a shallow foundation in clayey soil is unaffected by the position of water table, where in sandy soil, it is very much affected”.
Answer
Sign in to view the complete answer paper.
What is negative skin friction?
Answer
Sign in to view the complete answer paper.
State the permissible settlements for isolated and raft foundations in clays and Sandy Soils.
Answer
Sign in to view the complete answer paper.
Part B
Define significant depth of soil exploration? Give values for depth of soil exploration and number of bore holes for Multi storey buildings, closely spaced footings and Highway in filling and cutting.
Answer
Sign in to view the complete answer paper.
Explain in detail the rotary drilling technique. State also its advantages over other methods of boring.
Answer
Sign in to view the complete answer paper.
Explain Standard Penetration Test and corrections applied to observed N value. Illustrate test with figure.
Answer
Sign in to view the complete answer paper.
Calculate the factor of safety with respect to cohesion of clay slope laid at 1 in 2 to a height of 10m, if φ=12°, c=25kN/m2 and γ=19kN/m3. Calculate the safe height of the embankment for a factor of safety of 1.5. Assume the stability number as 0.91.
Answer
Sign in to view the complete answer paper.
What is stability factor? Discuss the importance and uses of stability charts in the analysis of stability of slopes.
Answer
Sign in to view the complete answer paper.
An infinite dry sandy slope is just stable at a slope angle of 35°. Unit weight of sand = 20 kN/m3. In monsoon, water starts flowing through the sand down the slope. At what inclination of slope will it be stable in such condition?
Answer
Sign in to view the complete answer paper.
Explain the different types of earth pressures with practical examples. Also explain how you will estimate the total active earth pressure experienced by a retaining wall with a vertical back retaining a cohesionless soil with horizontal surface.
Answer
Sign in to view the complete answer paper.
What are the different modes of failure of retaining walls? Explain with the help of neat sketches.
Answer
Sign in to view the complete answer paper.
List the types of foundations and explain how to select the suitable foundation for the given type of structure. Also differentiate between general shear failure, punching shear failure, and local shear failure.
Answer
Sign in to view the complete answer paper.
A 4 m wide strip footing is founded at a depth of 1.5 m below the ground surface in c-φ soil. The water table is at a depth of 5.5 m below ground surface. The properties of soil are: c' = 35 kN/m2, φ' = 28.63°, γsat = 19 kN/m3, γbulk = 17 kN/m3, γw = 9.81 kN/m3. Determine the net safe bearing capacity for local shear failure of soil using Terzaghi’s theory (Use F.O.S = 2.5).
Answer
Sign in to view the complete answer paper.
In a two layered cohesive soil, bored piles of 300mm are installed. The top layer has a thickness of 5m and the bottom one is of considerable depth. The "c" value of top layer is 40kN/m2 and that of the bottom is 100kN/m2. Determine the length of the pile required to carry a safe load of 400kN. Assume a F.S. of 3.
Answer
Sign in to view the complete answer paper.
A drop hammer weighing 60 kN and having an effective fall of 0.75 m drives an RCC pile weighing 30 kN. The average settlement per blow is 1.4 cm. The total elastic compression is 1.8 cm. Assume the coefficient of restitution as 0.3 and a factor of safety is 3, determine the allowable load on pile.
Answer
Sign in to view the complete answer paper.
Design a friction pile group to carry a load of 3500 kN including the weight of pile cap, at a site where the soil is uniform clay to a depth of 10 m underlain by rock. The average compressive strength of clay is 50 kN/m2. The clay may be assumed to be of normal sensitivity and normally loaded with a liquid limit of 70%. Adopt a factor of safety 2.5 against shear failure.
Answer
Sign in to view the complete answer paper.