摘要
中和村隧道设计为双幅三车道隧道，单幅隧道净高5m，净宽16．4m，左、右幅隧道净距为12m，在施工开挖过程采用3台阶开挖，上覆围岩为全～强风化泥岩夹砂岩，岩体覆盖层厚度约为12m，岩体的完整性和稳定性差。在进洞开挖过程中，采用平行施工，施工引起了地表的变形和破坏，左右幅隧道之间的岩璧产生了一条平行隧道轴线方向的裂缝，为保证隧道顺利开挖，需要对隧道左右幅的施工步距进行优化。采用三维有限元对三种不同的施工步距的应力和位移进行数值模拟，模拟计算结果表明：随着施工步距的增加，洞内的和地表的变形呈线性减小，施工步距为0、10、20和30m时，其顶拱的沉降分别为90mm、50mm、30mm和27mm。当施工步距大于20m，隧道相邻施工的影响较小。通过现场调整，确定施工步距为20m，其沉降高度在30mm以内，能够保证隧道的安全施工，说明通过综合确定岩体力学参数，采用三维有限元对隧道开挖施工步距数值模拟计算来优化隧道施工步距，这种方法不仅有效而且可行。
Zhonghecun tunnel design for dual three lane tunnel, single tunnel width 5m,height 16.5m, left, fight tunnel is 12M, in the process of excavation using 3 step excavation, overlying rock is weathered mudstone to sandstone, rock cover thickness is about 12M, the integrity and stability of rock mass difference. In the process of hole digging, the parallel construction, construction caused the deformation and failure surface, cracks between left and right images tunnel rock wall produced a parallel to the tunnel axis direction, in order to ensure the smooth excavation tunnel. Need to step on tunnel around the amplitude distance optimization. The three-dimensional finite element of three kinds of different construction step away from the stress and displacement of numerical simulation, the simulation results show that： with the increasing construction step, the surface deformation and decreases linearly, the construction step distance of 0, 10, 20 and 30m, the crown settlement are 90mm 30mm, 50mm, and 27mm. When the construction step is larger than 20m, less influence of construction of adjacent tunnel. Through on-site adjustment, determine the construction step distance is 20m, the height is within 30mm, which can ensure the safety of the tunnel construction, the mechanical parameters of rock mass are determined by comprehensive, three-dimensional finite element for the tunnel excavation step numerical simulation to optimize the tunnel construction step, and this method is effective and feasible.
关键词
隧道开挖
有限元
施工步距优化
Tunnel Excavation
Finite Element
Construction Step Optimization
