Why are weep holes provided at the back of retaining walls?
Coulomb’s theory of earth pressure is based on
For a sand having an internal friction of 30°, the ratio of passive to active lateral earth pressure will be
Kp/Ka will be the ratio of passive to active earth pressure.
The nature of earth pressure above dredge line behind a cantilever sheet pile wall is
The critical height of an unsupported vertical cut in a cohesive soil is given by
where, C = unit cohesion
ϕ = angle of internal friction
γ = unit weight of soil
Passive pressure in soil is associated with
Passive pressure compresses soil horizontally. It occurs when the retaining wall moves towards the backfill. Active pressure stretches soil horizontally and exerts tensile force in soil layer. It occurs when the retaining wall moves away from the backfill.
Coefficient of earth pressure at rest is
Ka < K0 < Kp
To stabilise a concrete cantilever retaining wall against sliding, the ratio of sliding force to resisting force should be
Factor of safety against sliding,
∑FR = sum of the horizontal resisting forces
∑Fd = sum of horizontal driving forces.
Usually Fs ≥ 1.55
∴ Ratio of sliding force to resisting force
The pore water pressure in the capillary zone is
The maximum permissible eccentricity of a retaining wall of width B to avoid failure in tension is
qmin for an eccentrically loaded footing
for no tension, qmin > 0