JNTU
JNTU B.Tech III FOUNDATION ENGINEERING Previous Question Paper (December - 2018 - 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.
PART - A
List the soil exploration methods.
Answer
Common soil exploration methods include: 1. Test pits (trial pits), 2. Borings (auger, wash, percussion, and rotary drilling), 3. Geophysical methods (seismic refraction and electrical resistivity), and 4. Sounding methods (Standard Penetration Test and Cone Penetration Test).
Describe the split spoon sampler uses.
Answer
The split spoon sampler is primarily used in the Standard Penetration Test (SPT) to obtain disturbed soil samples from boreholes. It allows for the measurement of penetration resistance, which correlates to the relative density of cohesionless soils and the consistency of cohesive soils.
What is a stability number?
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What are the causes of slope failure?
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Give the types of retaining walls.
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Differentiate Rankine’s and Coulombs theories.
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What are types of piles?
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Explain the criteria for selection of foundations.
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Discuss about sinking of wells.
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What are shapes of wells?
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PART - B
Discuss the sub soil investigation methods in detail.
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Describe the Standard Penetration Test and its importance in Geotechnical engineering.
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Differentiate between disturbed and undisturbed samples.
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Explain any one penetration test procedure.
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Explain planning and investigation of soils.
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A proposed cutting in a homogeneous cohesive soil will have a slope angle of 25 degrees and will be 8.0 m deep. Using Taylor’s stability chart, determine the factor of safety against shear failure in respect of the soils of:
a) c_u=45 kN/m^2; ϕ_u=0; γ=19 kN/m^3; depth factor is large; and
b) c_u=45 kN/m^2; ϕ_u=0; γ=19 kN/m^3; the cohesive layer overlies a hard layer of shale, present at a depth of 12 m.
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A vertical cut is made in a clay deposit. Find the height of the cut which can be temporarily supported γ=16 kN/m^3, c=30 kN/m^2, ϕ=0 degrees.
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Explain the types of slope failures with neat sketches.
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Discuss the Rankine’s earth pressure theory on passive earth pressure in cohesionless soils.
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A retaining wall is 7 m high, with its back face smooth and vertical. It retains sand with its surface horizontal. Using Rankine’s theory, determine active earth pressure at the base when the backfill is (i) dry, (ii) saturated and (iii) submerged, with water table at 2 m below the surface. Take γ_t=18 kN/m^3, γ_sat=21 kN/m^3 and ϕ=30 degrees.
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Consider a 5m high frictionless retaining wall with a vertical back and inclined backfill. The inclination of the backfill with the horizontal, α=10 degrees. For the backfill, given γ=18 kN/m^3, c'=5 kN/m^2, ϕ'=25 degrees. Determine Rankine’s active force per unit length of the wall after the occurrence of the tensile crack.
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A square foundation is of 1m depth. The footing will carry a gross mass of 30,000kg. Using a factor of safety of 3, determine the size of the footing. Given soil properties: γ=1850 kg/m^3, c'=0, ϕ'=30 degrees.
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Discuss different methods for the installation of piles. How would you estimate the load carrying capacity of a pile in cohesionless soils?
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A pile group consisting of 9 piles is arranged in 3 rows with 3 piles in each row. Diameter of each pile is 35 cm and spacing is 1.2 m. Length of pile is 10 m. The piles are driven completely in clayey soil having unconfined compressive strength of 100 kN/m^2. The piles are designed as frictional. Determine the capacity of pile group. Take α=0.7.
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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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With a neat sketch, state different components of a pneumatic caisson.
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What is a well foundation? What are its types? Discuss the components of well foundation with neat sketch.
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Briefly explain the procedure adopted in well sinking and bring out the problems that are encountered in open sinking.
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