Three-dimensional flexible boundary construction method and its influence on the #br#
deformation development of gravel soil by discrete element simulation
Jiang Chenglong Xu Chengshun Zhang Xiaoling Wang Xiaoli
Key Laboratory of Urban Security and Disaster Engineering, Beijing University of Technology, Beijing 100124, China
Abstract： Based on the discrete element platform, the drained triaxial tests of gravel soil were carried out. For these tests, the method of staggered spherical particle of constructing the flexible boundary and the unfolding method of applying the constant confining water pressure were improved. By using particle flow code (PFC3D), three-dimensional discrete element models of traditional rigid boundary and spherical particle flexible boundary were established, respectively, for numerical simulations of drained triaxial tests with different gravel contents. Furthermore, the effects of boundary conditions on the simulation of the deformation and development of gravel soil were studied from the perspectives of macro-failure morphology and micro-mechanical properties, shear zone evolution, and development of force chains at the boundary. The numerical results show that: in the cases of rigid boundaries, the failure of the specimen occurs earlier, which is inconsistent with the results of the laboratory test; while in the cases of flexible boundaries, the failure of the specimen occurs later, conforming well with the laboratory test; With the flexible boundaries, the uneven bulging deformation at failure can be observed in the middle of the specimen, and the inside asymmetric X-shaped shear band is formed, while with the rigid boundaries, the deformation of the specimen appears to be the collapsed failure. Based on the comparison of distribution and evolution of the boundary force chain between the two boundaries, it is found that the force chain of the flexible boundary is evenly distributed with more balanced strength; for the rigid boundary, however, stress blind zones and stress concentration may occur with the evolution of the force chain. Hence, based on the macro and micro analyses, it is recommended to apply the flexible boundaries rather than rigid boundaries for better numerical simulations.
蒋成龙 许成顺 张小玲 王晓丽. 三维柔性边界构建方法及其对砾质土变形发展影响的#br#
离散元数值研究[J]. 土木工程学报, 2021, 54(5): 77-86.
Jiang Chenglong Xu Chengshun Zhang Xiaoling Wang Xiaoli. Three-dimensional flexible boundary construction method and its influence on the #br#
deformation development of gravel soil by discrete element simulation. 土木工程学报, 2021, 54(5): 77-86.
