落石冲击棚洞结构的PFC3D数值模拟研究

PFC3D Simulation Study of Rockfall Impact to Shed Tunnel Structure

摘要: 以离散元理论为基础，采用颗粒流软件PFC建立落石冲击棚洞模型，在有回填土和无回填土两种工况下，模拟山体落石冲击框架棚洞，并对框架棚洞不同部位的冲击效应进行研究。研究表明：在落石冲击作用下，棚洞结构同一部位的动力响应不同，不同部位的动力响应也不相同，靠近落石冲击部位附近以剪应力为控制应力，破坏形式是剪切破坏，顶板端部则以正应力为控制应力，破坏形式是挤压破坏；有回填土情况下落石冲击效应小于无回填土，说明回填土对落石冲击具有非常好的缓冲作用；回填土的布置对顶板在落石冲击作用下的受力情况有影响。

Abstract: Based on the discrete element theory, a particle model was made to simulate the process of rockfall impact to shed cave under with and without backfill soil and the impact effect of different parts of the shed structure was studied and analyzed. The results drew conclusions as below: The stress response of the same part was different and meanwhile, the dynamic response of different parts was neither different under the action of rockfall impact. The shear stress is taken as the control stress near the impact position of the falling rock, and the failure form is shear failure. At the end of the roof, the normal stress is used as the control stress, and the failure form is extrusion failure. The impact effect of backfill is less than that of non-backfill, which indicates that backfill has very good buffering effect on rockfall impact, and the layout of backfill has an effect on the stress distribution of roof under rockfall impact.