特大跨隧道在双侧壁岛坑法施工下的数值模拟

摘要:

依托实际项目，运用FLAC3D进行后处理，模拟双侧壁导坑法用于V级围岩的施工，全面展示了暗挖隧洞右洞的分步开挖对左洞初期支护应力、右洞周围围岩变形的变化规律。结果表明：对于开挖洞在既有洞初期支护上产生的支护轴向应力规律，双侧壁导坑法和全断面开挖理论规律基本一致。开挖洞在双侧壁导坑工法下，地表沉降会出现下导坑较上导坑对地表沉降影响更大的规律。在偏压工况下，开挖对于地面沉降量在大偏压侧较小偏压侧更明显。导坑法对地面沉降会产生peck曲线的叠加效应，但最终沉降曲线满足peck沉降理论。

Abstract:

Relying on the actual project, FLAC3D is used for post-treatment to simulate the construction of class V surrounding rock by double wall heading method, which comprehensively shows the variation law of step-by-step excavation of the right tunnel on the initial support stress of the left tunnel and the deformation of surrounding rock around the right tunnel. The results show that the axial stress law of the excavation tunnel on the initial support of the existing tunnel is basically the same as that of the full face excavation theory. Under the construction method of double wall heading, the surface settlement will be more affected by the lower heading than the upper heading. Under the condition of bias pressure, the ground settlement caused by excavation is smaller on the large bias pressure side and more obvious on the bias pressure side. The heading method will produce the superposition effect of peck curve on land settlement, but the final settlement curve meets the peck settlement theory.