### Multiple Choice Questions and Answers Soil Mechanics and Foundation Engineering

01. A plane inclined at an angle ‘φ’ to the horizontal at which the soil is expected to stay in the absence of any lateral support, is known as

(A) Natural slope line
(B) Repose line
(C) The φ line
(D) All the above

02. Rise of water table above the ground surface causes

(A) Equal increase in pore water pressure and total stress
(B) Equal decrease in pore water pressure and total stress
(C) Increase in pore water pressure but decrease in total stress
(D) Decrease in pore water pressure but increase in total stress

03. Terzaghi’s theory of one dimensional consolidation assumes

(A) Soil is homogeneous and fully saturated
(B) Water and soil particles are incompressible
(C) Deformation of the soil, is entirely due to change in volume
(D) All the above

04. If the material of the base of the Casagrande liquid limit device on which the cup containing soil paste drops is softer than the standard hard rubber, then

(A) The liquid limit of soil always increases
(B) The liquid limit of soil always decreases
(C) The liquid limit of soil may increase
(D) The liquid limit of soil may decrease

05. A triaxial shear test is preferred to direct shear test, because

(A) It can be performed under all three drainage conditions with complete control
(B) Precise measurement of pore pressure and change in volume during test, is not possible
(C) Stress distribution on the failure plane, is non uniform
(D) None of these

06. The average coefficient of permeability of natural deposits

(A) Parallel to stratification is always greater than that perpendicular to stratification
(B) Parallel to stratification is always less than that perpendicular to stratification
(C) Is always same in both directions
(D) Parallel to stratification may or may not be greater than that perpendicular to stratification

07. Pick up the correct statement from the following:

(A) The dry density reduces by addition of water after attaining optimum moisture content
(B) The line joining the peak of three moisture content graphs obtained by using three compactive energies, is called line of optimus
(C) Well graded coarse grained soils can be compacted to a very high density as compared to fine grained soils
(D) All the above

08. The shear strength of a soil

(A) Is directly proportional to the angle of internal friction of the soil (B) Is inversely proportional to the angle of internal friction of the soil
(C) Decreases with increase in normal stress
(D) Decreases with decrease in normal stress

09. Pick up the correct statement from the following:

(A) The object of classifying soils is to arrange them into groups according to their properties and behaviour
(B) A soil classification system is meant to provide an accepted and systematic method of describing the various types of soils eliminating personal factors
(C) The first category of soil classification is based on grain size of the soil
(D) All the above

10. The major principal stress in an element of cohesion-less soil within the backfill of a retaining wall is

(A) Vertical if the soil is in an active state of plastic equilibrium
(B) Vertical if the soil is in a passive state of plastic equilibrium
(C) Inclined at 45° to the vertical plane
(D) None of the above

11. A grillage foundation

(A) Is provided for heavily loaded isolated columns
(B) Is treated as spread foundation
(C) Consists of two sets of perpendicularly placed steel beams
(D) All the above

12. Effective stress on soil

(A) Increases voids ratio and decreases permeability
(B) Increases both voids ratio and permeability
(C) Decreases both voids ratio and permeability
(D) Decreases voids ratio and increases permeability

13. Hydrometer readings are corrected for:

(A) Temperature correction
(B) Meniscus correction
(C) Dispersing agent correction
(D) Temperature, meniscus and dispersing agent corrections

14. The ultimate consolidation settlement of a structure resting on a soil

(A) Decreases with the increase in the initial voids ratio
(B) Decreases with the decrease in the plastic limit
(C) Increases with the increase in the initial voids ratio
(D) Increases with the decrease in the porosity of the soil

15. Select the incorrect statement.

(A) In a direct shear box test, the plane of shear failure is predetermined
(B) Better control is achieved on the drainage of the soil in a triaxial compression test
(C) Stress distribution on the failure plane in the case of triaxial compression test is uniform
(D) Unconfined compression test can be carried out on all types of soils

16. Factor of safety against sliding of a slope, is the ratio of

(A) Actual cohesion to that required to maintain stability of slope (B) Shear strength to shear stress along the surface
(C) Neither (a) nor (b)
(D) Both (a) and (b)

17. The angle of internal friction, is least for

(A) Angular-grained loose sand
(B) Angular -grained dense sand
(C) Round-grained loose sand
(D) Clays

18. Dispersed type of soil structure is an arrangement comprising particles having

(A) Face to face or parallel orientation
(B) Edge to edge orientation
(C) Edge to face orientation
(D) All of the above

19. The neutral stress in a soil mass is

(A) Force per neutral area
(B) Force per effective area
(C) Stress taken up by the pore water
(D) Stress taken up by solid particles

20. The coefficient of compressibility of soil, is the ratio of

(A) Stress to strain
(B) Strain to stress
(C) Stress to settlement

21. A clay subjected to pressure in excess to its present over-burden, is said to be

(A) Pre-compressed
(B) Pre-consolidated
(C) Over-consolidated
(D) All the above

22. Physical properties of a permeant which influence permeability are

(A) Viscosity only
(B) Unit weight only
(C) Both viscosity and unit weight
(D) None of the above

23. Pick up the correct statement from the following:

(A) The range of water content between the liquid limit and plastic limit is called plasticity index
(B) The ratio of the liquid limit minus the natural water content to the plasticity index of soils, is called consistency index
(C) The ratio of natural water content minus its plastic limit to its plasticity index is called liquidity index
(D) All the above

24. Rankine’s theory of active earth pressure assumes

(A) Soil mass is homogeneous, dry and cohesionless
(B) Ground surface is a plane which may be horizontal or inclined (C) Back of the wall is vertical and smooth
(D) All the above

25. For testing a saturated clay for shear strength, the test recommended, is

(A) Direct shear test
(B) Triaxial compression test
(C) Unconfined compression test
(D) All the above

26. Coefficient of permeability of soil

(A) Does not depend upon temperature
(B) Increases with the increase in temperature
(C) Increases with the decrease in temperature
(D) None of the above

27. The ratio of volume of air voids to the volume of total voids, is known as

(A) Air content
(B) Percentage air voids
(C) Percentage voids
(D) Porosity

28. Pick up the correct statement from the following:

(A) In soils, the flow index indicates variation in shear strength with water content
(B) Liquid limit minus plastic limit, is known as plasticity index of the soil
(C) Plastic limit minus shrinkage limit, is known as shrinkage index of the soil

(D) All the above

29. The triaxial apparatus is usually used for

(A) Unconsolidated-undrained test
(B) Consolidated-undrained test
(C) Drained test
(D) All the above tests

30. Which one of the following clays behaves like a dense sand?

(A) Over-consolidated clay with a high over-consolidation ratio
(B) Over-consolidated clay with a low over-consolidation ratio
(C) Normally consolidated clay
(D) Under-consolidated clay

31. During seepage through a soil, direction of seepage is always

(A) Parallel to equipotential lines
(B) Perpendicular to stream lines
(C) Perpendicular to equipotential lines
(D) None of these

32. The seepage force in a soil, is

(A) Perpendicular to the equipotential lines
(B) Proportional to the exit gradient
(C) Proportional to the head loss
(D) All the above

33. Pick up the correct statement from the following:

(A) Coefficient of compressibility is the decrease in void ratio per unit increase of pressure
(B) The percent settlement at any time is called degree of consolidation
(C) Time factor is a dimensionless quantity
(D) All the above

(A) Only in fixed ring type consolidometer
(B) Only in floating ring type consolidometer
(C) Both (A) and (B)
(D) None of the above

35. The property of a soil which allows it to be deformed rapidly without rupture, elastic rebound and also a volume change, is known

(A) Porosity
(B) Plasticity
(C) Permeability
(D) Ductility

36. Failure of the stability of slopes, generally occurs along

(A) Slip plane
(B) A horizontal surface
(C) A curved surface
(D) All the surfaces

37. The shearing force acting along the slice of a curved surface of slippage, causes the soil to slide

(A) Down at the centre
(B) Down at the toe
(C) Upward at the centre
(D) None of these

38. With the increase in the amount of compaction energy

(A) Optimum water content increases but maximum dry density decreases
(B) Optimum water content decreases but maximum dry density increases
(C) Both optimum water content and maximum dry density increase (D) Both optimum water content and maximum dry density decrease

39. Soils containing organic matters

(A) Are of spongy nature
(B) Swell with decrease of moisture
(C) Shrink with increase of moisture content
(D) None of these

40. Buoyant unit weight equals the saturated density

(A) Multiplied by unit weight of water
(B) Divided by unit weight of water
(C) Plus unit weight of water
(D) Minus unit weight of water

41. The change of moisture content of soils, changes the

(A) Value of the angle of repose
(B) Amount of compaction required
(C) Cohesive strength of soil
(D) All the above

42. Skempton’s pore pressure coefficient B for saturated soil is

(A) 1
(B) Zero
(C) Between 0 and 1
(D) Greater than 1

43. The density of soil can be increased

(A) By reducing the space occupied by air
(B) By elastic compression of soil grains
(C) By expelling water from pores
(D) All the above

44. Pick up the correct statement from the following:

(A) Kaolinite is most stable clay
(B) Kaolinite shows a very little sign of swelling on wetting
(C) Kaolinite is also called China clay
(D) All the above

45. Pick up the correct definition from the following:

(A) The lateral pressure exerted by the soil when the retaining wall moves away from the back fill, is generally known as active earth pressure of the soil
(B) The lateral pressure exerted by the soil when the retaining wail moves towards the soil, is generally known as ‘Passive earth pressure of the soil
(C) The lateral pressure exerted by the soil when the retaining wall has no movement relative to the back fill, is known as ‘earth pressure at rest of the soil
(D) All the above

46. Shear strength of a soil is a unique function of

(A) Effective stress only
(B) Total stress only
(C) Both effective stress and total stress
(D) None of the above

47. Laplacian fundamental equation for a non-compressible flow in three dimensions, is

(A) (δu/δx) + (δv/δy) + (δw/δz) = 0
(B) (δ²h/δx²) + (δ²h/δy²) + (δ²h/δz²) = 0
(C) (δ²ϕ/δx²) + (δ²ϕ/δy²) + (δ²ϕ/δz²) = ϕ
(D) None of these

48. 260 g of wet soil was taken in a pycnometer jar of weight 400 g in order to find the moisture content in the soil, with specific gravity of soil particles 2.75. The weight of soil and remaining water filled in pycnometer without air bubbles was 1415 g and the weight of pycnometer filled with water alone was 1275 g. The moisture content in the soil is

(A) 24.2 %
(B) 18.2 %
(C) 53.8 %
(D) None of these

49. The method of the slices is applicable to

(A) Homogenous soils
(B) Stratified soils
(C) Saturated soils
(D) Non-uniform slopes

50. The angle that Coulomb’s failure envelope makes with the horizontal is called

(A) Cohesion
(B) Angle of internal friction
(C) Angle of repose
(D) None of the above