Zhe LI^{+}, Gao-Feng ZHAO^{#}

*Tianjin University, China*

In this work, the distinct lattice spring model (DLSM) is further developed for handling geotechnical problems. The DLSM is proposed for analyzing material failure and crack propagation. The DLSM is a kind of discrete element method, it represents materials by a system of discrete particles interacting via springs, can naturally predict deformation and collapse of soil correctly without any special operation. To ensure safety, supporting structure is widely applied to resist large deformation of soil. However, the dimension scale of the supporting structure is usually much smaller than it of soil. It’s unsuitable for DLSM to directly analyze structure and soil together as a full 3D model. Therefore, the structural element, beam finite element, is adopted to model the structure. Meanwhile, a method to couple the DLSM and the beam is developed. The beam has 6 degrees of freedom (DOF), 3 DOFs for displacements in x, y, and z axes, and 3 DOFs for rotations around x, y, and z axes. In DLSM, only 3 displacement DOFs are used. To solve this mismatch, one beam node connects to several DLSM particles interacting via normal springs. The cross-section features of the beam are considered in this model. The coupling method is based on the translation of force, the bending moment transfer is handled by the coupling method as well. Based on this coupling method, the cross-section naturally affects the interaction without any other redundant operations. The central difference method is used in the beam integration, which is the same as that in the DLSM. The beam and the coupling method get verifications via some classical boundary value problems. The results show that the algorithm has good accuracy and robustness.