GEO TERMS: LATERAL EARTH PRESSURE

Question 1

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

Answer 1

A. vertical if the soil is in an active state of plastic equilibrium

Question 2

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

Answer 2

D. all the above

Question 3

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

Answer 3

D. all the above

Question 4

in active state of plastic equilibrium in a non-cohesive soil with horizontal ground surface

A. major principal stress is horizontal
B. minor principal stress is vertical
C. major principal stress is vertical
D. minor and major principal stresses are equally inclined to horizontal

Answer 4

C. major principal stress is vertical

Question 5

if the back fill is having a uniform surcharge of intensity per unit area, the lateral pressure will be _____

A. q times the lateral pressure within the surface
B. 1/q times the lateral pressure within the surface
C. equal to a fill of height Z equal to q/r, where r is the density of the backfill
D. none of these

Answer 5

C. equal to a fill of height Z equal to q/r, where r is the density of the backfill

Question 6

Rankine’s theory of earth pressure assumes that the back of the wall is _____

A. plane and smooth
B. plane and rough
C. vertical and smooth
D. vertical and rough

Answer 6

C. vertical and smooth

Question 7

according to Coulomb’s wedge theory, the active earth pressure slides the wedge _____

A. down and outwards on a slip surface
B. up and inwards on a slip surface
C. horizontal upward and parallel to base
D. horizontal inward and parallel to base

Answer 7

A. down and outwards on a slip surface

Question 8

the earth pressure of a soil at rest, is proportional to _____ (where is the angle of internal friction of the soil)

A. tan (45° - φ)
B. tan (45° + φ)
C. tan^2 (45° - φ)
D. none of these

Answer 8

D. none of these

Question 9

the effect of cohesion on a soil is to _____

A. reduce both the active earth pressure intensity and passive earth pressure intensity

B. increase both the active earth pressure intensity and passive earth pressure intensity

C. reduce the active earth pressure intensity but to increase the passive earth pressure intensity

D. increase the active earth pressure intensity but to reduce the passive earth pressure intensity

Answer 9

C. reduce the active earth pressure intensity but to increase the passive earth pressure intensity

Question 10

the coefficient ka (k sub a) of the active earth pressure is given by _____

A. ka = (1 - tanφ) / (1 + tanφ)
B. ka = (1 + tanφ) / (1 - tanφ)
C. ka = (1 + sinφ) / (1 - sinφ)
D. ka = (1 - sinφ) / (1 + sinφ)

Answer 10

D. ka = (1 - sinφ) / (1 + sinφ)

Question 11

the active earth pressure of a soil is proportional to _____ (where φ is the angle of friction of the soil)

A. tan(45° - φ)
B. tan^2 (45° + φ/2)
C. tan^2 (45° - φ/2)
D. tan (45° + φ)

Answer 11

C. tan^2 (45° - φ/2)

Question 12

a failure wedge retaining wall

A. moves away from the backfill
B. moves towards the backfill
C. sinks downwards
D. stresses equally by vertical and horizontal forces

Answer 12

A. moves away from the backfill

Question 13

the total active earth pressure due to dry back fill with no surcharge, acts at H/3 above the base of the wall and is directly proportional to _____

A. H
B. √H
C. H^2
D. H^3

Answer 13

C. H^2

Question 14

back fill with a sloping surface exerts a total active pressure P, on the wall of height H and acts at _____

A. H/4 above the base parallel to base
B. H/2 above the base parallel to base
C. H/3 above the base parallel to base
D. H/5 above the base parallel to base

Answer 14

C. H/3 above the base parallel to base

Question 15

coefficient of earth pressure at rest is _____

A. less than active earth pressure but greater than passive earth pressure

B. greater than active earth pressure but less than passive
earth pressure

C. greater than both the active earth pressure and passive earth pressure

D. less than both the active and passive earth pressures

Answer 15

B. greater than active earth pressure but less than passive
earth pressure

Question 16

Coulomb’s wedge theory assumes that _____

A. back fill is dry, cohesionless, homogeneous and isotropic
B. slip surface is the plane which passes through the heel of the wall
C. position and direction of the resultant earth pressure are known
D. all the above

Answer 16

D. all the above

Question 17

the lateral earth pressure on a retaining wall

A. is equal to mass of the soil retained
B. proportional to the depth of the soil
C. proportional to the square of the depth of the soil
D. proportional to the friction of the soil

Answer 17

B. proportional to the depth of the soil

Question 18

the passive earth pressure of a soil is proportional to _____ (where φ is the angle of internal friction of the soil)

A. tan (45° - φ)
B. tan (45° + φ)
C. tan^2 (45° - φ)
D. tan^2 (45° + φ)

Answer 18

D. tan^2 (45° + φ)