Supporting mechanism of rigid-flexible composition retaining structure in sand ground using discrete element method

The supporting mechanism of a rigid-flexible composite retaining structure (RFCRS) is investigated by the discrete element method (DEM) using the rolling resistance linear (RRlinear) contact model. A DEM model with a natural initial stress state is first generated by the brick filling method (BFM) and the effectiveness and accuracy of the modelling process are further checked. Then, a relation between the macroscopic and microscopic parameters is constructed and calibrated. The mechanical characteristics of the RFCRS in terms of the stress field, displacement field, force chain and energy field are explored by comparison with rigid retaining structure (RRS). Numerical results have revealed that compared with the RRS, the earth pressure of the RFCRS is reduced by approximately 13.96%, and the peak earth pressure of the RFCRS is reduced by approximately 47.86%. The supporting mechanism of the RFCRS is divided into two aspects. On the one hand, flexible materials deform under earth pressure, and thus the lateral earth pressure changes from the at-rest to the active state. On the other hand, flexible materials absorb part of the energy through deformation. Additionally, as the thickness of flexible materials increases, the lateral earth pressure decreases and the tendency of decreasing earth pressure tends to weaken.