Test: Lateral Earth Pressures & Retaining Walls - 2 - Civil Engineering (CE) MCQ

Critical depth = 2Z_c

Passive earth pressure coefficient,

The earth pressure distribution due to the surcharge load is = q.K_a and is uniform throughout the length of the retaining wall.

Factor of safety against overturning is given by

and should be between 1.5 to 2

For c - ϕ soil active earth pressure,

at z = 0

The active earth pressure on the back of the pile tries to push the wall away from fill and lateral passive resistance due to soil below the dredge line tries to restore the pile.

In Coulomb’s theory failure piane is assumed to be plane. The sliding wedge acts as a rigid body. The wall is assumed rough.

For earth dam during steady seepage, the critical condition occurs for D/S slope. For rapid drawdown case U/S slope represents critical condition. In both cases the pore water pressure is determined from flow net.
During construction, the excess pore pressure is likely to develop and stability of U/S and D/S slopes during or immediately after construction should be considered. 

Depth of tension crack
 

Rankine's earth pressure theory assumes that the retaining wall is smooth and vertical and the ground surface is piane which may be inclined or horizontal.