JNTU
JNTU B.Tech IV FOUNDATION ENGINEERING Previous Question Paper (July - 2023 - R16)
Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. In Part B, Answer any one question from each unit. Each question carries 10 marks.
Main
List out the various methods of site exploration.
Answer
The common methods of site exploration include: 1) Open trial pits, 2) Borings (Auger, Wash, Percussion, and Rotary), 3) Geophysical methods (Seismic refraction and Electrical resistivity), and 4) Sounding methods (Standard Penetration Test and Cone Penetration Test).
Write the essential features and applications of Rotary sampler.
Answer
The Rotary sampler features a rotating drill bit that cuts through hard soil or rock, allowing for the collection of high-quality, relatively undisturbed core samples. It is primarily applied in hard soils, rock formations, and deep exploration where other boring methods fail to penetrate.
What are the different factors of safety used in the stability of slopes?
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Why Taylor’s stability number is not suitable for cohesionless soils?
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How do tension cracks influence the distribution of active earth pressure in pure cohesion?
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How to calculate bearing pressure of cantilever retaining wall?
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What is the significance of permissible settlement?
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State the factors affecting location of footing.
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What are the problems encountered in well sinking?
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Write note on floating foundations.
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Explain in detail the various factors that help to decide the depth and number of bore holes required for sub soil exploration.
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Explain in detail the rotary drilling technique. State also its advantages over other methods of boring.
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If you are in-charge of subsoil exploration of important structures, how would you decide the depth of exploration? List out the factors you will consider and their importance.
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What are the probable types of failure of a slope? Explain them briefly.
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How a slope is analysed using Fellenius method of slices by locating critical slip centre? Derive an expression for the factor of safety.
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Explain Bishop’s simplified method. Derive an expression for the factor of safety.
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An infinite dry sandy slope is just stable at a slope angle of 35°. Unit weight of sand is 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
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What is the total active force per meter length of the retaining wall? Where will this force act? The properties of soil are: Angle of shearing resistance φ = 30°, Angle of wall friction δ = 2/3φ, Angle of surcharge β = 10°, Angle of batter α = 80°, Bulk unit weight of soil retained γ = 17 kN/m3. Use Coulomb’s equation.
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What are the factors affecting stability of retaining walls?
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Discuss the principles of the design of retaining walls.
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What is the basis for classifying foundations into shallow and deep? Briefly explain the situations in which different types of shallow foundations are adopted.
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A square footing carries a load of 800kN. The depth of the footing is 1.5m. The properties of the soil are c=0, φ=38°, and γ=18.5kN/m3. Determine the size of the footing for a factor of safety of 3 against shear failure. What will be the changes in the size of the footing, if the water table rises to ground level. (for φ=38°, the Nc=52, Nq=49 and Nγ=64).
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How do you estimate the settlement of a footing on sand using plate load test? How is depth correction applied?
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Write note on methods of designing of raft foundations.
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Design a square pile group to carry 400kN in clay with unconfined compression strength of 60 kN/m2. The piles are 30 cm diameter and 6 m long. Adhesion factor may be taken as 0.6. Take factor of safety = 3.
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What are the precautions to be cared for during sinking of wells? How are tilts and shifts of wells rectified?
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With a neat sketch, state different components of a well foundation.
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