JNTU
JNTU B.Tech III FOUNDATION ENGINEERING Previous Question Paper (May - 2019 - R15)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
What are the limitations in plate load test?
Answer
The plate load test is limited by the size effect, as it only reflects the soil properties within a depth of about twice the plate width. It also provides short-term settlement data, failing to account for long-term consolidation settlement, and is highly sensitive to the water table and soil heterogeneity.
During a field exploration, coring of rock was required. The core barrel was advanced 1.5 m during the coring. The length of the core recovered was 0.98 m. What was the recovery ratio?
Answer
The recovery ratio is calculated as the ratio of the length of core recovered to the length of the core run. Given: Length of core recovered = 0.98 m; Length of core run = 1.5 m.
What is stability factor?
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Discuss the importance and uses of stability charts in the analysis of stability of slopes.
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What is a critical height?
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Compare Rankine’s theory and Coulomb’s theory.
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“Dynamic formulae are applicable only in case of driven piles”. Justify.
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State the circumstances to go for combined footing.
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What are the different shapes of well?
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What are the safety measures to be taken during well sinking?
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Part B
What do you understand about disturbed and undisturbed samples? How do you obtain undisturbed samples?
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Discuss standard penetration test. What are the various corrections? What is the importance of the test?
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What are the probable types of failure of a slope? Explain.
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What is Taylors stability number and how to use the stability chart?
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How is Bishops rigorous analysis different from his simplified method?
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List out the factors affecting the factor of safety of an infinite slope in a clay soil.
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Explain briefly, why are retaining walls usually designed for active earth pressure?
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How does Rankine’s approach differ from Coulombs approach in the estimation of active earth pressure?
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A retaining wall with soft saturated clay back fill is 6m high. The unit weight of clay is 16 kN/m3 and cohesion is 15 kN/m2. Determine:
a) Maximum depth of tensile cracks
b) Total active earth pressure before cracks occur and
c) Total active earth pressure after the cracks.
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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 classify pile foundations on the basis of material, influence of pile installation, load transfer, method of installation?
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What is negative skin friction? How is it calculated for a single pile and group of piles in clay?
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With a neat sketch explain various components of well foundation.
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Sketch an open well foundation and show the various components. State the functions of various components.
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What are the causes of Tilts and Shifts in well foundations and describe any one method adopted for rectifying them.
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