The Coulomb’s theory of earth pressure is a classical theory used to calculate the lateral earth pressure exerted on retaining structures, such as walls or embankments. The theory was first developed by the French physicist and engineer Charles-Augustin de Coulomb in the late 18th century.
According to Coulomb’s theory, the lateral earth pressure acting on a retaining wall is proportional to the angle of internal friction of the soil, the cohesion of the soil, and the vertical stress acting on the soil. The lateral earth pressure is also affected by the angle of inclination of the wall, the surcharge load on the soil, and the depth of the soil behind the wall.
Coulomb’s theory is based on the assumption that the soil is homogenous and behaves like a dry granular material with no cohesion. However, in reality, soils are not always homogenous, and they may contain some amount of cohesion. Therefore, the accuracy of Coulomb’s theory decreases when applied to cohesive soils.
Despite its limitations, Coulomb’s theory is still widely used in the design of retaining structures today, especially for non-cohesive soils. It provides a simple and relatively accurate method for calculating lateral earth pressure, which is an essential parameter in the design of retaining walls, bridge abutments, and other engineering structures that interact with soil.
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