SSC JE–100 MCQs in Soil Mechanics, topic-wise, moderate level, and each question has a short, clear explanation
SOIL MECHANICS – 100 MCQs
(Topic-wise | Moderate | SSC JE Pattern | With Explanations)
🔹 TOPIC 1: BASIC SOIL PROPERTIES (Q1–Q15)
Q1. Void ratio of a soil mass is defined as:
A) Volume of voids / Total volume
B) Volume of voids / Volume of solids
C) Volume of solids / Total volume
D) Volume of air / Volume of water
✅ Ans: B
📝 Explanation: Void ratio compares empty space to solid material, not total volume.
Q2. Relationship between porosity (n) and void ratio (e) is:
A)
B)
C)
D)
✅ Ans: A
📝 Explanation: This is a standard derivation from phase relationships.
Q3. If degree of saturation is 100%, soil is called:
A) Dry
B) Partially saturated
C) Saturated
D) Submerged
✅ Ans: C
📝 Explanation: All voids are filled with water.
Q4. Typical specific gravity of soil solids is:
A) 1.0–1.5
B) 2.5–2.7
C) 3.5–4.0
D) >4.0
✅ Ans: B
📝 Explanation: Most mineral soils fall in this range.
Q5. Bulk unit weight includes weight of:
A) Solids only
B) Solids + water
C) Solids + air
D) Solids + water + air
✅ Ans: D
📝 Explanation: Bulk unit weight accounts for all three phases.
Q6. Submerged unit weight is equal to:
A) γsat − γw
B) γd + γw
C) γw − γsat
D) γsat + γw
✅ Ans: A
📝 Explanation: Buoyant force reduces effective weight.
Q7. For dry soil, which phase is absent?
A) Solid
B) Water
C) Air
D) Void
✅ Ans: B
📝 Explanation: Dry soil contains no moisture.
Q8. Water content is defined as:
A) Weight of water / Total weight
B) Weight of water / Weight of solids
C) Volume of water / Volume of solids
D) Volume of voids / Volume of solids
✅ Ans: B
Q9. A high void ratio indicates soil is:
A) Dense
B) Loose
C) Hard
D) Cemented
✅ Ans: B
Q10. Degree of saturation is the ratio of:
A) Volume of air / voids
B) Volume of water / voids
C) Volume of water / solids
D) Volume of solids / voids
✅ Ans: B
Q11. Unit weight of water is approximately:
A) 9.81 kN/m³
B) 1 kN/m³
C) 100 kN/m³
D) 10.81 kN/m³
✅ Ans: A
Q12. Which property mostly affects compressibility?
A) Void ratio
B) Specific gravity
C) Unit weight
D) Porosity
✅ Ans: A
Q13. For saturated soil, air content is:
A) Maximum
B) Partial
C) Zero
D) 100%
✅ Ans: C
Q14. Three phases of soil are:
A) Rock, water, air
B) Solid, liquid, gas
C) Sand, silt, clay
D) Gravel, sand, clay
✅ Ans: B
Q15. Density of soil is mainly affected by:
A) Grain shape
B) Void ratio
C) Color
D) Mineralogy
✅ Ans: B
🔹 TOPIC 2: SOIL CLASSIFICATION (Q16–Q30)
Q16. Purpose of soil classification is to:
A) Increase strength
B) Identify engineering behavior
C) Reduce cost
D) Improve compaction
✅ Ans: B
Q17. Indian Standard soil classification is based on:
A) Grain size only
B) Plasticity only
C) Grain size + plasticity
D) Density
✅ Ans: C
Q18. Coarse-grained soil contains more than:
A) 50% passing 75 µm
B) 50% retained on 75 µm
C) 75% passing 4.75 mm
D) 25% retained on 4.75 mm
✅ Ans: B
Q19. Gravel size is:
A) > 4.75 mm
B) < 0.075 mm
C) 0.075–4.75 mm
D) 2–4.75 mm
✅ Ans: A
Q20. Plasticity Index =
A) LL − SL
B) LL − PL
C) PL − SL
D) WL − SL
✅ Ans: B
Q21. Soil with PI = 0 is:
A) Clay
B) Silt
C) Sand
D) Non-plastic
✅ Ans: D
Q22. Casagrande chart is used to distinguish between:
A) Sand and gravel
B) Clay and silt
C) Fine and coarse soil
D) Organic soil
✅ Ans: B
Q23. Highly plastic clay is denoted as:
A) CL
B) CH
C) ML
D) MH
✅ Ans: B
Q24. Well-graded soil contains:
A) Uniform particles
B) Wide range of sizes
C) Only fine particles
D) Only coarse particles
✅ Ans: B
Q25. Black cotton soil mainly contains:
A) Kaolinite
B) Illite
C) Montmorillonite
D) Quartz
✅ Ans: C
Q26. Expansive soil problem occurs mainly due to:
A) Sand
B) Silt
C) Clay minerals
D) Gravel
✅ Ans: C
Q27. Best foundation soil among following is:
A) Soft clay
B) Organic soil
C) Well-graded sand
D) Peat
✅ Ans: C
Q28. Coefficient of uniformity (Cu) for well-graded sand should be:
A) < 2
B) > 4
C) = 1
D) > 10
✅ Ans: B
Q29. Soil with LL > 50% is classified as:
A) Low plastic
B) Medium plastic
C) High plastic
D) Non-plastic
✅ Ans: C
Q30. Clay shows high:
A) Permeability
B) Compressibility
C) Strength
D) Density
✅ Ans: B
🔹 TOPIC 3: ATTERBERG LIMITS (Q31–Q45)
Q31. Liquid limit corresponds to soil changing from:
A) Solid to semi-solid
B) Semi-solid to plastic
C) Plastic to liquid
D) Liquid to gas
✅ Ans: C
Q32. Plastic limit is determined by:
A) Casagrande cup
B) Cone penetration
C) Rolling threads
D) Sieve analysis
✅ Ans: C
Q33. Shrinkage limit is water content at which:
A) Volume stops decreasing
B) Weight becomes zero
C) Soil cracks
D) Soil flows
✅ Ans: A
Q34. Plasticity Index indicates:
A) Strength
B) Compressibility
C) Plasticity range
D) Density
✅ Ans: C
Q35. High LL indicates:
A) Low compressibility
B) High compressibility
C) High permeability
D) Low settlement
✅ Ans: B
Q36. Liquid limit test uses:
A) Rolling
B) Dropping cup
C) Vibration
D) Compaction
✅ Ans: B
Q37. Soil with PI < 5 is considered:
A) Highly plastic
B) Medium plastic
C) Slightly plastic
D) Expansive
✅ Ans: C
Q38. Plasticity chart separates fine soils based on:
A) Density
B) Strength
C) LL and PI
D) Moisture
✅ Ans: C
Q39. Shrinkage ratio relates:
A) Volume change to water content
B) Weight change to volume
C) Volume change to solids
D) Density change
✅ Ans: A
Q40. At PL, soil just begins to:
A) Crack
B) Flow
C) Crumble
D) Shrink
✅ Ans: C
Q41. Clay soils generally have:
A) Low PI
B) Medium PI
C) High PI
D) Zero PI
✅ Ans: C
Q42. Silt generally lies:
A) Above A-line
B) Below A-line
C) On A-line
D) Outside chart
✅ Ans: B
Q43. If LL = PL, PI = ?
A) 1
B) 0
C) −1
D) Infinity
✅ Ans: B
Q44. Plasticity increases with increase in:
A) Sand content
B) Silt content
C) Clay content
D) Gravel content
✅ Ans: C
Q45. Which soil has maximum shrinkage?
A) Sand
B) Silt
C) Clay
D) Gravel
✅ Ans: C
🔹 TOPIC 4: PERMEABILITY & SEEPAGE (Q46–Q60)
Q46. Darcy’s law is valid for:
A) Turbulent flow
B) Laminar flow
C) Capillary flow
D) Piping
✅ Ans: B
Q47. Unit of permeability is:
A) m²
B) m/s
C) N/m²
D) kg/m³
✅ Ans: B
Q48. Constant head test is suitable for:
A) Clay
B) Silt
C) Sand
D) Peat
✅ Ans: C
Q49. Falling head test is suitable for:
A) Gravel
B) Coarse sand
C) Clay
D) Boulder
✅ Ans: C
Q50. Permeability mainly depends on:
A) Void ratio
B) Grain size
C) Viscosity
D) All of these
✅ Ans: D
Q51. Clay has _____ permeability.
A) High
B) Medium
C) Low
D) Very high
✅ Ans: C
Q52. Seepage velocity is equal to:
A) Discharge velocity × porosity
B) Discharge velocity / porosity
C) Discharge velocity × void ratio
D) Same as discharge velocity
✅ Ans: B
Q53. Critical hydraulic gradient causes:
A) Compaction
B) Boiling
C) Settlement
D) Shrinkage
✅ Ans: B
Q54. Piping failure occurs due to:
A) Shear failure
B) Excess seepage force
C) Overloading
D) Low density
✅ Ans: B
Q55. Flow net consists of:
A) Stress lines
B) Flow & equipotential lines
C) Contours
D) Load lines
✅ Ans: B
Q56. Equipotential lines indicate:
A) Equal velocity
B) Equal head
C) Equal discharge
D) Equal pressure
✅ Ans: B
Q57. Maximum permeability soil is:
A) Clay
B) Silt
C) Sand
D) Gravel
✅ Ans: D
Q58. Quick sand condition occurs when:
A) i > ic
B) i < ic
C) i = 0
D) i = 1
✅ Ans: A
Q59. Seepage force acts in direction of:
A) Load
B) Flow
C) Gravity
D) Pressure
✅ Ans: B
Q60. Flow nets are drawn for:
A) Strength
B) Settlement
C) Seepage analysis
D) Compaction
✅ Ans: C
SOIL MECHANICS – PART-2
(Q61–Q100 with Explanations)
🔹 TOPIC 5: COMPACTION (Q61–Q75)
Q61. Compaction of soil mainly results in:
A) Increase in void ratio
B) Increase in permeability
C) Increase in strength
D) Increase in compressibility
✅ Ans: C
📝 Explanation: Compaction reduces air voids, making soil denser and stronger.
Q62. Compaction differs from consolidation because compaction involves:
A) Expulsion of water
B) Expulsion of air
C) Increase in pore pressure
D) Drainage
✅ Ans: B
📝 Explanation: Compaction removes air; consolidation removes water.
Q63. Maximum dry density occurs at:
A) Zero moisture content
B) Shrinkage limit
C) Optimum moisture content
D) Liquid limit
✅ Ans: C
Q64. The Proctor test determines:
A) Permeability
B) Shear strength
C) OMC and MDD
D) Settlement
✅ Ans: C
Q65. Increase in compaction energy will:
A) Increase OMC
B) Decrease OMC
C) Not affect OMC
D) Increase void ratio
✅ Ans: B
📝 Explanation: More energy packs soil better, requiring less water for lubrication.
Q66. Heavy compaction results in:
A) Lower dry density
B) Higher dry density
C) No change in density
D) Lower strength
✅ Ans: B
Q67. Best roller for compacting clayey soil is:
A) Smooth wheel roller
B) Vibratory roller
C) Sheep foot roller
D) Grid roller
✅ Ans: C
📝 Explanation: Kneading action suits cohesive soils.
Q68. Best roller for compacting sandy soil is:
A) Sheep foot roller
B) Pneumatic roller
C) Vibratory roller
D) Tamping roller
✅ Ans: C
📝 Explanation: Vibration rearranges sand grains effectively.
Q69. Zero air voids line represents:
A) Maximum dry density curve
B) 100% saturation line
C) Minimum density line
D) Porosity curve
✅ Ans: B
Q70. Dry density (γd) is related to bulk density (γ) by:
A) γd = γ(1 + w)
B) γd = γ / (1 + w)
C) γd = γ − w
D) γd = γ × w
✅ Ans: B
Q71. Main purpose of field compaction is to reduce:
A) Strength
B) Stability
C) Settlement
D) Density
✅ Ans: C
Q72. OMC stands for:
A) Original moisture content
B) Optimum moisture content
C) Operational moisture content
D) Maximum moisture content
✅ Ans: B
Q73. Higher maximum dry density indicates:
A) Loose soil
B) Dense soil
C) Weak soil
D) Expansive soil
✅ Ans: B
Q74. Field compaction is checked by:
A) Sieve analysis
B) Core cutter test
C) Consolidation test
D) Shear test
✅ Ans: B
Q75. Which soil shows maximum improvement due to compaction?
A) Gravel
B) Sand
C) Clay
D) Silt
✅ Ans: C
📝 Explanation: Clay shows large volume change when compacted.
🔹 TOPIC 6: SHEAR STRENGTH OF SOIL (Q76–Q90)
Q76. Shear strength of soil depends on:
A) Cohesion
B) Angle of friction
C) Both cohesion and friction
D) Density only
✅ Ans: C
Q77. Mohr–Coulomb failure criterion is:
A) τ = σ
B) τ = c + σ tan φ
C) τ = σ tan φ
D) τ = c
✅ Ans: B
Q78. For cohesionless soil, cohesion (c) is:
A) High
B) Moderate
C) Zero
D) Negative
✅ Ans: C
Q79. Direct shear test is mainly used to determine:
A) Compressibility
B) Permeability
C) Shear strength
D) Density
✅ Ans: C
Q80. Triaxial test is preferred over direct shear because:
A) Cheaper
B) Easier
C) Stress conditions are controlled
D) Faster
✅ Ans: C
Q81. In an undrained triaxial test:
A) Drainage is allowed
B) Drainage is not allowed
C) Partial drainage
D) Excess pore pressure is zero
✅ Ans: B
Q82. Angle of internal friction mainly depends on:
A) Grain shape
B) Grain size
C) Mineralogy
D) Moisture content
✅ Ans: A
Q83. Clay soils generally have:
A) High φ
B) Low φ
C) Zero φ
D) Infinite φ
✅ Ans: B
Q84. Which soil has highest shear strength?
A) Loose sand
B) Dense sand
C) Soft clay
D) Silt
✅ Ans: B
Q85. Unconfined compression test is suitable for:
A) Sand
B) Gravel
C) Clay
D) Silt
✅ Ans: C
Q86. Unconfined compressive strength (qu) is equal to:
A) c
B) 2c
C) φ
D) σ
✅ Ans: B
📝 Explanation: For saturated clay, φ ≈ 0, so qu = 2c.
Q87. Shear failure occurs when:
A) Shear stress > shear strength
B) Shear stress < shear strength
C) Stress = zero
D) Strength increases
✅ Ans: A
Q88. In cohesive soil, shear strength mainly depends on:
A) Friction
B) Cohesion
C) Density
D) Moisture
✅ Ans: B
Q89. Quickest shear strength test is:
A) Triaxial test
B) Direct shear test
C) Unconfined compression test
D) Vane shear test
✅ Ans: C
Q90. Factor of safety is defined as:
A) Stress / strength
B) Strength / stress
C) Load / area
D) Area / load
✅ Ans: B
🔹 TOPIC 7: CONSOLIDATION & SETTLEMENT (Q91–Q100)
Q91. Consolidation in soil occurs due to:
A) Compression of solids
B) Expulsion of air
C) Expulsion of water
D) Increase in load only
✅ Ans: C
Q92. Consolidation is significant in:
A) Sand
B) Gravel
C) Clay
D) Rock
✅ Ans: C
Q93. Primary consolidation is due to:
A) Air expulsion
B) Water expulsion
C) Soil creep
D) Elastic rebound
✅ Ans: B
Q94. Secondary consolidation is due to:
A) Drainage
B) Pore pressure dissipation
C) Soil creep
D) Compaction
✅ Ans: C
Q95. Terzaghi’s consolidation theory applies mainly to:
A) Sand
B) Clay
C) Gravel
D) Silt
✅ Ans: B
Q96. Coefficient of consolidation depends on:
A) Permeability
B) Compressibility
C) Both A and B
D) Density only
✅ Ans: C
Q97. Time for consolidation is proportional to:
A) Thickness
B) Thickness²
C) Permeability
D) Load
✅ Ans: B
Q98. Maximum settlement occurs in:
A) Sand
B) Gravel
C) Clay
D) Rock
✅ Ans: C
Q99. Consolidation test is also called:
A) Triaxial test
B) Oedometer test
C) Shear test
D) Plate load test
✅ Ans: B
Q100. Immediate settlement occurs due to:
A) Drainage
B) Elastic deformation
C) Creep
D) Consolidation
✅ Ans: B