平行双隧洞台阶法开挖有限元模拟

Finite Element Simulation of Parallel Double Tunnel Excavation by Bench Method

摘要: 本文通过COMSOL对平行双隧洞建立有限元模拟模型，并对开挖的隧洞进行岩土力学承载力数值模拟，分析对比平行双隧洞在上下台阶开挖过程中围岩的应力重分布规律、拱部沉降量、围岩应力、塑性区变化规律。通过分析这些重要参数，结果表明：拱顶上端土体厚度越大，应力集中现象越明显；上台阶的开挖会使得围岩产生应变和应力重分布，但达到稳定后，下台阶的开挖不会产生应力和应变的变化；在斜坡内部开挖隧洞，沉降量呈现先增加后减少，再先增加后减少的趋势。

Abstract: In this paper, the finite element simulation model of the parallel double tunnel was established by COMSOL, and the geotechnical mechanical bearing capacity of the excavated tunnel was numerically simulated. The stress redistribution law, arch settlement, surrounding rock stress and plastic zone variation law of the parallel double tunnel in the process of upper and lower step excavation were analyzed and compared. By analyzing these important parameters, the results show that the larger the soil thickness is, the more obvious the stress concentration phenomenon is. The excavation of the upper step will cause strain and the stress redistribution of the surrounding rock, but the excavation of the lower step will not cause stress and strain change after reaching stability. When the tunnel is dug inside the slope, the settlement first increases, then decreases, then increases and then decreases.