软岩隧道开挖方法数值模拟分析

Numerical analysis on tunnel excavating methods in soft rock

论述了适用于纱帽山隧道Ⅴ级围岩的开挖方法,采用大型非线性有限元分析软件ADINA,对适用于双线分离式公路隧道Ⅴ级围岩的三种开挖施工方法进行数值模拟;运用ADINA自带的单元生死功能动态模拟开挖支护过程,对比左导洞先行开挖编制的施工工序、台阶分部开挖法和上下台阶留核心土法三种开挖方法,分析三种开挖方法对隧道变形的影响。结果表明:针对左导洞先行开挖编制的施工工序其中隔壁起到减跨作用,从而控制沉降;它与台阶分部开挖法在开挖后位移场分布基本是对称的,在量值上有略小差别,不会造成地表不均匀变形,不会影响洞室的稳定;台阶分部开挖法左侧地表变形略大于右侧,且差值大于针对左导洞先行开挖编制的施工工序。

The ADINA is used to investigate the excavating methods which are applicable to the V class surrounding rocks of the tunnel in Shamao Mountain and make a numerical simulation for three kinds of excavating methods which are applicable to bilinear separable highway tunnels. The function of element birth and death of ADINA is used for dynamic simulation of excavation support process. Compared with these three excavating methods, the influences of the methods on the tunnel deformation are analyzed. The results show that the bulkhead has the effect of reducing span in the construction process prepared for the excavation in advance of the left guide hole so that the sedimentation can be controlled. The displacement field of the excavation in advance is almost symmetrical to the one of the stage excavation method and they are of slight difference in magnitude, so it will not lead to the deformation of the surface of earth and influence the stability of the cavern. The deformation of the earth surface on the left side is a little more than the one on the fight side in stage excavation method, and the difference is greater than that from the construction process prepared for the excavation in advance of the left guide hole.