Effect of non-simultaneous movement of adjacent twin-trapdoor on soil arching effect through discrete-element method simulation

Abstract

Soil arching effect commonly exists in geotechnical engineering practice. Previous relevant studies mainly focused on the mechanical and deformation responses of soil arching effect upon simultaneous movement of trapdoor or subsoil under multi-trapdoor conditions. However, non-simultaneous movement of trapdoors or subsoil also exists, lacking of attention and investigation. This study presents a numerical simulation of twin-trapdoor tests using the discrete element method (DEM), by moving the adjacent trapdoors non-simultaneously. The results indicate that the height of soil arching increases with the increase of the initial displacement difference between the adjacent trapdoors (defined as the displacement of the formerly-lowered trapdoor, when the latterly-lowered trapdoor starts to move down). The latterly-forming soil arching facilitates the load recovery of the formerly-forming soil arching. With the initial displacement difference between the adjacent trapdoors increasing, the formerly-forming soil arching is weakened more significantly due to the development of the latterly-forming soil arching. This observation is supported by a larger soil arching ratio, larger contact forces, less anisotropy of normal force, and a decreasing porosity within the formerly-forming soil arching field. By contrast, when the latterly-forming soil arching starts to develop, it is insignificantly influenced by the formerly-forming arching throughout the development process.