All Free Civil Engineering MCQs with Answers
Every Civil Engineering question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
631 questions · page 19 of 32
- A. Arithmetic mean of layer permeabilities
- B. Geometric mean of layer permeabilities
- C. Harmonic mean of layer permeabilities
- D. Maximum permeability of the layers
Explanation: For flow perpendicular to soil layers, the equivalent permeability is obtained from a thickness-weighted harmonic mean.
Correct answer: Harmonic mean of layer permeabilities- A. Elastic distortion of soil grains
- B. Sudden collapse of air voids
- C. Immediate expulsion of pore water
- D. Creep and rearrangement of soil structure
Explanation: Secondary consolidation is the gradual deformation that continues after primary consolidation and is mainly caused by creep and particle…
Correct answer: Creep and rearrangement of soil structure- A. Neither consolidated nor drained before shearing
- B. Consolidated but not drained before shearing
- C. Consolidated and drained before shearing
- D. Drained but not consolidated before shearing
Explanation: In the unconsolidated undrained test, drainage is prevented during both application of cell pressure and shearing.
Correct answer: Neither consolidated nor drained before shearing- A. Cohesion and footing embedment
- B. Soil unit weight and footing width
- C. Water content and plasticity index
- D. Pile length and shaft roughness
Explanation: The term 0.5 gamma B N-gamma is the soil unit weight contribution in the bearing capacity equation.
Correct answer: Soil unit weight and footing width- A. A flexible raft above the ground
- B. Separate piles with no interaction
- C. A single enlarged pile shaft
- D. A frictionless column in the soil
Explanation: In block failure, the piles and the enclosed soil move together as one composite block.
Correct answer: A single enlarged pile shaft- A. Convert a shallow footing into a pile
- B. Increase the soil plasticity index
- C. Eliminate the need for reinforcement
- D. Reach a zone with smaller moisture variation
Explanation: Moisture changes near the ground surface cause swelling and shrinkage in expansive soils.
Correct answer: Reach a zone with smaller moisture variation- A. Soft saturated clay
- B. Dense gravel deposits
- C. Clean coarse sand
- D. Sound weathered rock
Explanation: The field vane test directly measures the undrained shear strength of soft, saturated cohesive soil.
Correct answer: Soft saturated clay368. The air content of a partially saturated soil is defined as the ratio of the volume of air to the:
- A. total volume of soil
- B. volume of voids
- C. volume of soil solids
- D. volume of water
Explanation: Air content is the proportion of the void space occupied by air, so it is Va divided by Vv.
Correct answer: volume of voids369. In soil classification, the effective grain size D10 represents the particle size corresponding to:
- A. 50 percent finer by weight
- B. 10 percent coarser by weight
- C. 10 percent finer by weight
- D. 90 percent finer by weight
Explanation: D10 is read from the particle-size distribution curve at 10 percent finer.
Correct answer: 10 percent finer by weight- A. hydraulic gradient
- B. coefficient of permeability
- C. specific gravity
- D. porosity
Explanation: Darcy discharge velocity is based on the total cross-sectional area, whereas actual water movement occurs through the voids.
Correct answer: porosity- A. specific gravity and void ratio
- B. coefficient of permeability and grain size
- C. cohesion and plasticity index
- D. liquid limit and water content
Explanation: The critical gradient is approximately (Gs minus 1) divided by (1 plus e).
Correct answer: specific gravity and void ratio- A. low dry density after compaction
- B. excessive exit hydraulic gradient
- C. high plasticity of clay
- D. large angle of internal friction
Explanation: Piping occurs when seepage forces remove soil particles, usually near the downstream exit where the hydraulic gradient is high.
Correct answer: excessive exit hydraulic gradient373. On a compaction graph, the zero-air-voids line represents the dry unit weight corresponding to:
- A. constant air content of five percent
- B. maximum dry density at optimum water content
- C. complete saturation at each water content
- D. complete removal of water from the soil
Explanation: The zero-air-voids line is the theoretical limit for a soil with no air in its voids, meaning complete saturation.
Correct answer: complete saturation at each water content- A. gamma w divided by k mv
- B. mv divided by k gamma w
- C. k mv gamma w
- D. k divided by mv gamma w
Explanation: The usual relationship is Cv = k divided by mv gamma w. It combines permeability with compressibility and the unit weight of water…
Correct answer: k divided by mv gamma w- A. pore water is allowed to escape
- B. no volume change is permitted
- C. the specimen remains completely undrained
- D. only total stress is considered
Explanation: Drainage valves remain open in a drained test, allowing pore water to escape and permitting effective stress changes during shearing.
Correct answer: pore water is allowed to escape- A. 1 plus sin phi
- B. 1 minus sin phi
- C. tan squared of 45 degrees plus phi over 2
- D. tan squared of 45 degrees minus phi over 2
Explanation: Jaky's expression for normally consolidated soil is K0 = 1 minus sin phi.
Correct answer: 1 minus sin phi- A. remains unchanged for every slope angle
- B. increases because confinement is greater
- C. decreases because the failure zone is reduced
- D. becomes equal to the pile capacity
Explanation: A nearby slope reduces the lateral confinement and available soil mass supporting the footing, so bearing capacity decreases.
Correct answer: decreases because the failure zone is reduced- A. γwGs(1 + e)
- B. γwGs/(1 + e)
- C. γw(1 + e)/Gs
- D. γw(Gs + e)/(1 + e)
Explanation: For saturated soil, all voids contain water, so the total weight includes the solids and water occupying the voids.
Correct answer: γw(Gs + e)/(1 + e)- A. 35 percent
- B. 50 percent
- C. 65 percent
- D. 80 percent
Explanation: USCS classifies a soil as fine grained when 50 percent or more of its material passes the No.
Correct answer: 50 percent- A. square metres per second
- B. m per second
- C. kilonewtons per cubic metre
- D. cubic metres per second
Explanation: The coefficient of permeability represents the velocity associated with a unit hydraulic gradient, so its SI unit is length per time, or…
Correct answer: m per second