CE-701 Geo-Technical Engineering - Dec 2025 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aDraw the phase diagram for soils and derive from fundamentals : $es = Gw$
   How to answer

   • Draw three-phase diagram with solids, water, air with volumes and weights notation
   • Assume volume of solids Vs=1 or weight of solids Ws=1 as basis
   • Use definitions e=G, w, S, G to express weights/volumes
   • Derive eS = wG algebraically
2. 7 Marks
   bThe dry unit weight of a soil sample in the loosest state is $13.34\text{ kN/m}^3$ and in the densest state, it is $21.19\text{ kN/m}^3$. Determine the relative density of the sand when it has porosity of $33\%$. Assume the grain specific gravity as $2.68$.
   How to answer

   • Compute e_max from dry unit weight in loosest state and G
   • Compute e_min from dry unit weight in densest state and G
   • Convert given porosity 33% to natural void ratio e
   • Apply relative density formula Id = (e_max - e)/(e_max - e_min)
3. 7 Marks
   aA partially saturated sample has a density of $1.95\text{ g/cc}$ and a water content of $21\%$. If the specific gravity of soil solids is $2.65$, calculate the degree of saturation and void ratio.
   How to answer

   • Find dry density from bulk density and water content
   • Use gamma_d = G*gamma_w/(1+e) to get void ratio e
   • Use eS = wG to get degree of saturation S
   • Report S in % and e
4. 7 Marks
   bDefine Darcy's law, what are the limitations and factors affecting permeability of soil.
   How to answer

   • State Darcy's law v = ki with definitions
   • List limitations: laminar flow, saturated soil, validity limit
   • List factors: grain size, void ratio, structure, saturation, fluid properties
   • Brief explanation of each factor
5. 7 Marks
   aDescribe pumping-out methods for the determination of the coefficient of permeability in the field. What are their advantages and disadvantages?
   How to answer

   • Describe pumping-out test setup for unconfined and confined aquifers
   • Give discharge and drawdown formulas for k
   • List advantages: field-scale, reliable for design
   • List disadvantages: costly, time-consuming, needs observation wells
6. 7 Marks
   bThe water table in a deposit of uniform sand is located at $2\text{ m}$ below the ground surface. Assuming the soil above the water table is dry. Determine the effective stress at a depth of $5\text{ m}$ below the ground surface. The void ratio is $0.75$ and specific gravity of solids is $2.65$, if the soil above the water table is saturated by capillary action, what is the effective stress at that depth?
   How to answer

   • Compute dry and saturated unit weights from e and G
   • Compute total stress and pore pressure at 5 m depth for dry top case
   • Compute effective stress sigma' = sigma - u
   • Recompute with capillary saturation above water table and compare
7. 7 Marks
   aA concentrated load of $1000\text{ kN}$ is applied at the ground surface. Determine the vertical stress at a point 'P' which is $5\text{ m}$ directly below the load. Also calculate the vertical stress at a point 'R' which is at a depth of $5\text{ m}$ but at a horizontal distance of $3\text{ m}$ from the axis of the load. Use Westergaard's theory (Poisson's ratio=0).
   How to answer

   • State Westergaard vertical stress formula with Poisson ratio 0
   • Compute stress directly below load at z=5 m
   • Compute r/z ratio for offset point R
   • Compute reduced stress at R
8. 7 Marks
   bWhat is field compaction? Briefly describe different methods of field compaction.
   How to answer

   • Define field compaction and its objective
   • Describe rollers: smooth, pneumatic, sheepsfoot, vibratory
   • Mention suitability for soil types and lift control
   • Mention field density control
9. 7 Marks
   aUsing Boussinesq's expression, derive the expression for vertical stress at depth, h, under the centre of a circular area of radius, a, loaded uniformly with a load, q, at the surface of the mass of soil.
   How to answer

   • Start from Boussinesq point load vertical stress formula
   • Consider elemental ring of radius r and width dr with load q*2πr dr
   • Integrate from 0 to a at depth h under centre
   • Obtain sigma_z = q[1 - 1/(1+(a/h)^2)^{3/2}]
10. 7 Marks
    bWhat is coefficient of consolidation? What is its use in the settlement analysis?
    How to answer

    • Define coefficient of consolidation cv = k/(mv*gamma_w)
    • Explain time-rate of consolidation and Tv relation
    • Explain use in settlement-time and degree of consolidation
    • Mention determination from lab tests
11. 7 Marks
    aA clay layer, $10\text{m}$ thick, doubly drained, is expected to have a final settlement of $10\text{ cm}$. The coefficient of consolidation of the clay soil is $10^{-3}\text{ cm}^2/\text{s}$ for the relevant stress range. Plot the consolidation settlement vs time curve.
    How to answer

    • Compute drainage path H for doubly drained 10 m layer
    • Use Tv = cv*t/H^2 and U-Tv relation to get settlement S=U*Sf
    • Calculate times for U=10-100% and tabulate
    • Sketch S vs t and S vs log t curve shape
12. 7 Marks
    bDiscuss Terzaghi's theory of consolidation, starting the various assumptions and their Validity.
    How to answer

    • State Terzaghi one-dimensional consolidation equation
    • List assumptions: saturated, incompressible solids/water, Darcy's law etc.
    • Outline derivation and solution with Tv and U
    • Discuss validity and limitations
13. 7 Marks
    aExplain the types of shear test based on different drainage conditions.
    How to answer

    • Define UU, CU, CD tests with drainage stages
    • Explain consolidation and shearing drainage conditions
    • Mention pore pressure measurement and use
    • Mention suitability for soil and loading cases
14. 7 Marks
    bWhat are the types of geosynthetics used in soil engineering? Briefly explain their functions.
    How to answer

    • List geosynthetics: geotextiles, geogrids, geomembranes, geocells etc.
    • Explain functions: separation, filtration, drainage, reinforcement
    • Give soil engineering applications
    • Brief examples
15. 14 Marks
    Explain any two of the following:

    1. a)Factors affecting the shear strength of cohesive soils.
    2. b)Different types of compressibility
    3. c)Factors affecting soil compaction
    4. d)Origin and formation of soils
    How to answer

    • Select any two topics from (a)-(d)
    • Give definition, factors or classification for each
    • Add diagrams or examples where relevant
    • Conclude with engineering significance