渗流场对地铁隧道沉降与受力影响的流固耦合分析

地下水问题是富水地层地下结构设计与施工中普遍存在的问题。为探讨地下水流动对软岩地铁隧道的稳定性及衬砌支护受力的影响,根据流固耦合理论,采用三维快速拉格朗日有限差分方法,在不同地下水位及排水边界条件下,对开挖后洞室周边场地位移、应力场、孔隙水压力的分布情况进行了综合分析。结果显示,由渗流引起的渗透力一定程度上会增加隧道周边场地变形及衬砌应力。从围岩-支护结构共同作用的原理出发,验证了隧道开挖与支护结构设计时需要考虑渗流效应,反映了地下水确实对隧道稳定性有着重要影响。

Coupled Fluid-Mechanical Analysis of Settlement and Stability of Subway Tunnel

The groundwater problem in underground engineering is an important issue influencing the stability of subway tunnel.Based on the coupled fluid-mechanical theory,the finite difference method of fast Lagrangian analysis of continua is applied to analyze the fields of displacement,stress,and pore- pressure in the surrounding soils of an excavated tunnel under various conditions of groundwater levels, different depth of the tunnel.It can be concluded from the numerical simulation of excavation that the groundwater flow have an obvious effects on the distributions of displacement,stress and pore-pressure in the surrounding soil.The seepage forces of groundwater will increase the displacement in the soil around the tunnel and the stress in the tunnel linings.According to the basic deformation compatibility condition of surrounding soils and supporting structure of tunnels,the necessity of considering the seepage effect of ground water in design of tunnel excavation and its supporting structures has been proved in this paper to demonstrate the important effects of groundwater on the stability of tunnels.