JNTU
JNTU B.Tech III GEOTECHNICAL ENGINEERING Previous Question Paper (March - 2024 - R13)
Question paper consists of Part A, Part B. Part A is compulsory, which carries 25 marks. Answer all questions in Part A. 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
Differentiate between void ratio and porosity.
Answer
Void ratio (e) is defined as the ratio of the volume of voids to the volume of solids, expressed as
Porosity (n) is defined as the ratio of the volume of voids to the total volume of the soil mass, expressed as
Sketch the typical grain size distribution curves for (i) Well graded Soil, (ii) Poorly graded Soil.
Answer
The grain size distribution curve is plotted with the percentage finer on the y-axis (arithmetic scale) and particle size on the x-axis (logarithmic scale). A well-graded soil exhibits a broad, smooth S-shaped curve covering a wide range of particle sizes, indicating a good representation of all grain sizes. In contrast, a poorly graded soil is represented by a steep, narrow curve, indicating that the soil consists of particles of mostly one size (uniform) or lacks certain intermediate sizes (gap-graded).
What is Darcy’s Law?
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What are the salient characteristics of a flow net?
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What are the parameters can be obtained from the compaction test?
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Explain the Concept of pressure bulb.
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Define compression index.
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What is time factor in consolidation process?
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What is dilatency in Tri-axial Compression test?
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What are the three standard tri-axial shear tests with respect to drainage?
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Part B
Establish the relationship between degree of saturation, soil moisture content, specific gravity of soil particles and void ratio.
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The volume of an undisturbed clay sample having a natural water content of 40% is 25.6 cm3 and its wet weight is 0.435 N. Calculate the degree of saturation of the sample, if the grain specific gravity is 2.75.
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Briefly describe the “IS Soil Classification system”.
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Write a short note on Liquid limit test.
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What are the different methods for determination of the Coefficient of Permeability in a laboratory?
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A falling head permeability test was performed on a sample of clean, uniform sand. One minute was required for the initial head of 100 cm to fall to 50 cm in the stand pipe of the cross sectional area of 1.5 cm2. If the sample was 4 cm in diameter and 30 cm long, calculate the coefficient of permeability of the sand.
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Write short note on critical hydraulic gradient.
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Write short notes on “neutral” and “effective pressure”. What is the role of effective stress in Soil mechanics?
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Derive the principle of construction of Newmark’s chart and explain its uses.
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A 25 kN point load acts on the surface of a horizontal ground. Find the intensity of vertical pressure at 6 m directly below the load. Use Boussinesq’s equation.
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What are the various factors that affect the compaction of soils?
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Derive the expression for zero air void line for a specific gravity of 2.65.
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Discuss the spring analogy method.
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The co-ordinates of two points on a straight line section of a semi-logarithmic plot of compression diagram are e1 = 2.50, σ1 = 150 kN/m2; and e2 = 1.75, σ2 = 600 kN/m2. Calculate the compression index.
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Define pre consolidation pressure. In what ways its determination important in soil engineering practice? Describe a suitable procedure for determining the pre-consolidation pressure.
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Determine the amount of settlement given the following data: Thickness of compressible medium = 5 m, Coefficient of volume decrease = 0.0025 cm2/N, Pressure increment at the centre of the compressible medium = 150 kN/m2.
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Sketch the stress-strain relationship for dense and loose sand.
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For a normally consolidated clay φ’ = 30°. In a drained tri-axial test, the specimen failed at deviator stress of 200 kN/m2. What was the chamber confining pressure?
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Explain the basic difference a Direct shear and tri-axial compression test.
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A consolidated drained tri-axial test was conducted on a normally consolidated clay. The results were as follows: σ3 = 300 kN/m2; deviator stress, Δσdf = 350 kN/m2. Determine (i) the angle of internal friction, φ (ii) angle, θ that the failure plane makes with the major principal plane (iii) Normal stress, τf, on the failure plane.
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