Test: Rankine’s Theory - Civil Engineering (CE) MCQ

As originally proposed, Rankine’ s theory of lateral pressure is applied to uniform cohesion less soils only. Later, it was extended to include cohesive soil.

According to the assumption of Rankine’s theory, the soil mass is semi-infinite, homogeneous, dry and cohesion less.

The retaining walls are constructed of masonry or concrete, due to this the frictional force develops. The existence of the friction makes the resultant pressure inclined to the wall at an angle that approaches the frictional angle between the soil and the wall.

The earth pressure at rest, exerted on the back of the rigid, unyielding retaining structure, can be calculated using theory of elasticity.

K0 can be calculated by using the following equation as computed by Jacky in 1944:
K0 = 1 – sin φ.

The theory of lateral pressure was extended to cohesive, stratified, partially immersed and submerged soil was by Resal in 1910 and by Bell in 1915.

In Rankine’s theory the following cases of cohesionless backfill are considered
i) Dry or moist backfill with no surcharge
ii) Submerged backfill
iii) Backfill with a sloping surface and inclined back and surcharge.

The lateral pressure is made up of two components for wetted soil in back of the retaining wall:
i) Lateral pressure due to submerged weight ‘γ’ of the soil, and
ii) Lateral pressure due to water.

The value of K0 for different soils is:
i) Loose sand – 0.4
ii) Dense sand – 0.6
iii) Soft clay – 0.6
iv) Hard clay – 0.5.

Coefficient of earth pressure, K0 can be calculated using Jacky’s formula:
Given: φ = 26°
Formula: K0=1 – sin φ
K0 = 1 – sin 26°
K0 = 1 – 0.4383
K0 = 0.561628.