Discrete element study of stresses and deformation on gravity retaining wall under static loading

The study of gravity retaining wall supporting cohesionless soil is performed using the discrete element software Particle Flow Code (PFC), with emphasis on three-dimensional analysis at the grain scale, covering the transition from the initial state to the active state. The soil particles are represented by spherical balls and the rolling resistance linear contact model is used to include the shape effect. The rigid balls are connected by linear parallel bond contact model with a specified strength and stiffness to replicate the physical characteristics of retaining wall. The domain size is reduced by using high g criteria and scaling laws to enhance computational efficiency. The earth pressure coefficient obtained from the present study is compared with the existing analytical and experimental solutions. It is concluded that widely used Coulomb and Rankine methods underestimate the active earth pressure. The total earth thrust acting on the gravity wall is 67.3 kN/m acting at 0.301H above the wall base. The initial state shows a decrease in average coordination number from 5.0 to 3.3 at wall top indicating the debonding of grains and simultaneous decrease in density. In addition, the force chain distribution, porosity, lateral displacement, and axial displacement are investigated. A correlation between the earth pressure coefficient and lateral displacement is also established. The discrete analysis provided valuable insights into the particle-level mechanisms underlying the overall behavior of the retaining wall, contributing to a better understanding of its continuum response.

Graphical Abstract