According to Rankine Earth Pressure Theory, what assumption is made regarding failure?

The basis of Rankine Earth Pressure Theory is the assumption that failure occurs along a flat plane inclined to the wall, which is treated as a sliding plane. This model simplifies the analysis of earth pressures acting on retaining structures by assuming that the failure surface meets the wall at a defined angle, typically the angle of internal friction.

This inclination is determined by the properties of the soil, and it reflects how soil behaves under conditions of lateral earth pressure. These assumptions help engineers calculate the active and passive earth pressures that a wall must resist, enabling them to design structural supports effectively.

In the context of retaining walls and soil mechanics, this approach assumes that the sliding failure surface is key in predicting when and how failure will occur in the soil behind the wall. The flat failure plane simplifies the calculations and provides a reliable method for determining the structural forces acting on retaining walls.