不同开挖方法对公路隧道围岩稳定影响分析

Analysis of Influence of Different Excavation Methods on Surrounding Rock Stability of Highway Tunnels

位于我国西部的某公路隧道处于软弱地质围岩中,为了研究该公路隧道最优的开挖方法,基于有限元仿真软件MIDAS/GTS模拟隔壁法、环形留核心土法和台阶法3种不同的开挖方式对隧道围岩稳定性影响进行分析。有限元计算结果表明,3种不同的开挖方法不仅对隧道围岩卸荷的顺序存在较大差异,而且不同开挖方法对应的应力集中程度、应力应变大小及变化规律也不尽相同。通过分析3种开挖方式的应力和位移云图,详细对比了各开挖方式对应的各特征点X方向和Z方向应力值和位移值,综合考虑该公路隧道的围岩地质条件、施工进度、施工成本及施工安全,确定该隧道最优的开挖方式为台阶法开挖。

A highway tunnel located in the western part of China is in the soft geological surrounding rock.In order to study the optimal excavation method of the highway tunnel,this paper is based on the finite element simulation software MIDAS/GTS for the partition wall method,the annular core soil method and the step method.The excavation method is used to analyze the influence of tunnel surrounding rock stability.The finite element calculation results show that the three different excavation methods not only have different differences in the unloading order of tunnel surrounding rock,but also the stress concentration,stress strain and variation law of different excavation methods are not the same.By analyzing the stress and displacement cloud maps of the three excavation methods,the X-direction and Z-direction stress values and displacement values of each feature point of each excavation method are compared in detail,and the surrounding rock geological conditions,construction progress and construction of the highway tunnel are comprehensively considered.Cost and construction safety,the optimal excavation method of the tunnel is step method excavation.