多隧道开挖诱发山体变形与应力数值模拟

Numerical Simulation of Mountain Deformation and Stress Induced by Multi Tunnel Excavation

为了研究多隧道开挖过程中山体变形规律,借助有限元软件COMSOL Multiphysics建立了多隧道的二维模型,采用弹塑性方法及Drucker-Prager屈服准则。对多隧道穿越山体的情况下进行数值模拟分析,首先研究了隧道开挖前土体的应力状态;然后,进一步研究隧道开挖后土体的弹塑性行为。模拟过程中,将第一步中的土体当作弹性土,在第二步中加入土的塑性材料模型Drucker-Prager。在二维平面应变下求解,得到了隧道开挖应力主要集中在洞口周围,造成的土体变形主要位于隧道上方和左右两侧,变形主要以竖向地表沉降为主,关于隧道轴线对称两侧水平与竖直方向的变形规律相同。模拟结果表明隧道周围塑性区域的地表沉降和宽度,是预测开挖过程中加固材料用量的重要参数。

In order to study the deformation law of mountain in the process of multi tunnel excavation, a two-dimensional model of multi-tunnel is established by using the finite element software COMSOL multiphysics. The elastoplastic method and Drucker Prager Yield Criterion are adopted. Firstly, the stress state of soil before tunnel excavation is studied;secondly, the elastoplastic behavior of soil after tunnel excavation is further studied. In the simulation process, the soil in the first step is regarded as elastic soil, and the plastic material model Drucker Prager is added in the second step. The results show that the tunnel excavation stress is mainly concentrated around the tunnel portal, and the soil deformation is mainly located at the top and left and right sides of the tunnel. The deformation is mainly vertical surface settlement. The deformation law of the horizontal and vertical directions on both sides of the tunnel axis symmetry is the same. The simulation results show that the surface settlement and width of the plastic zone around the tunnel are important parameters to predict the amount of reinforcement material during excavation.