# Soil Mechanics & Foundation Engineering : Earth Pressure Theories

By Sajal Gupta|Updated : July 6th, 2021

## Earth Pressure Theories

### Rankine's Earth Pressure Theory

The Rankine's theory assumes that there is no wall friction (δ = 0), the ground and failure surfaces are straight planes, and that the resultant force acts parallel to the backfill slope.

In case of retaining structures, the earth retained may be filled up earth or natural soil. These backfill materials may exert certain lateral pressure on the wall. If the wall is rigid and does not move with the

## Earth Pressure Theories

### Rankine's Earth Pressure Theory

The Rankine's theory assumes that there is no wall friction (δ = 0), the ground and failure surfaces are straight planes, and that the resultant force acts parallel to the backfill slope.

In case of retaining structures, the earth retained may be filled up earth or natural soil. These backfill materials may exert certain lateral pressure on the wall. If the wall is rigid and does not move with the

pressure exerted on the wall, the soil behind the wall will be in a state of elastic equilibrium. Consider the prismatic element E in the backfill at depth, z, as shown in Fig.

### Active earth pressure:

Rankine's active earth pressure in the cohesionless soil

### Passive earth pressure:

Rankine's passive earth pressure in cohesionless soil

### Rankine's active earth pressure with a sloping cohesionless backfill surface

As in the case of horizontal backfill, active case of plastic equilibrium can be developed in the backfill by rotating the wall about A away from the backfill. Let AC be the plane of rupture and the soil in the wedge ABC is in the state of plastic equilibrium.

### Coulomb's Wedge Theory

Some Graphical solutions for lateral Earth Pressure are

• Culman's solution
• The trial wedge method
• The logarithmic spiral

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Member since Mar 2020
B.E- Civil, Thapar University, Patiala Cracked Gate-2017, 2018, 2020 1 yr work exp at Wapcos, MoWR