高地应力隧道台阶法施工过程数值模拟

结合高地应力区兰渝铁路某隧道实际施工方法,运用有限元分析软件MIDAS-GTS进行隧道三台阶法开挖数值模拟分析,通过选取合适物理力学参数进行建模,从模型中提取围岩位移、塑性区、二衬位移、轴力、弯矩等数据进行分析,通过对比分析,得出台阶法施工中应加强支护部位及支护控制措施(如超前支护、拱腰、拱脚加密锁脚锚管等),二衬受力、变形随侧压力系数变化趋势、二衬安全系数等,并和隧道实际监测数据进行对比分析,验证数值模拟的合理性和正确性,可以为高地应力隧道设计施工提供有益的参考。

Numerical Simulation on Construction Process of High Ground Stress Tunnel by Bench Method

In this paper the finite element analysis software MIDAS-GTS is used to simulate and analyze the excavation of tunnel by three-step method, combined with the practical construction method used in a carbonaceous phyllite tunnel at Lanzhou-Chongqing railroad located in Class V weak high ground stress area. Appropriate physical and mechanical parameters from code for design of railway tunnel are selected to establish the model, data such as the surrounding rock deformation, plastic zone, secondary lining displacement, axial force and bending moment are extracted for analysis. It is concluded that the supporting parts should be strengthened and the supporting control measures be adopted (such as advanced support, arch, arch foot encrypted with lock anchor pipe etc.), besides, the force in secondary lining, variation trend of deformation vs. lateral pressure coefficient, the safety coefficient of secondary lining etc. are obtained from the model and compared with the actual monitoring data of the tunnel, the conclusion is that the numerical simulation is correct and rational, which can serve as useful reference for design and construction of high ground stress tunnel.