双洞八车道小净距公路隧道七步台阶法开挖数值模拟

摘要

Using the finite difference software, the construction process of the seven steps bench method in twin highway tunnel with eight lanes and small clear-distance was simulated, and the law of the primary support's displacement and internal force varying with construction sequences were analyzed. The results show that the maximum compressive stress of primary support mainly distributes at each of the arch springing or wall corners after each excavation step; the largest axial force distributes at the sidewalls and wall corners close to the middle rock pillar; the maximum bending moment distributes at the vau the influence of right tunnel excavation on the axial force of left tunnel is smaller than the influence on the bending moment; the displacement of the tunnel vault is the biggest and the displacements of the tunnel arch springing and the hance far from the middle rock pillar are relatively small.%利用有限差分软件,模拟双洞八车道小净距公路隧道七步台阶法施工过程,分析初期支护随施工步序位移、内力的变化规律.研究表明:隧道初期支护最大压应力主要发生在各部开挖后的拱脚或墙角；最大轴力分布在两洞靠近中间岩柱的边墙和墙角,最大弯矩分布在拱顶；右洞开挖对左洞初期支护轴力影响较小,弯矩影响较大；拱顶住移最大,远离中间岩柱的拱脚和拱腰位移较小.