邻近建筑物的暗挖隧道施工数值模拟

软土中采用暗挖法开挖隧道往往会引起土体变形，由于城市中暗挖隧道多建在建筑物高度集中的地区，土体变形对邻近既有建筑物的损伤不容忽视。采用二维有限元方法对邻近中、低层建筑物(采用整体基础)工况下的暗挖隧道施工进行了模拟和分析，建筑物长15 m。研究结果表明：建筑物的存在会增大隧道开挖引起的地面沉降和衬砌的受力与变形，同时隧道开挖也会使邻近建筑物产生附加应力和变形。当隧道轴线与建筑物轴线的水平距离 0 m时，建筑物相对安全；当 时，建筑物会产生朝向隧道一侧的倾斜。当 为2.5～20 m时，产生较大的地面沉降，建筑物的首尾沉降差较大，建筑物较危险；当 为30～40 m时，建筑物的存在对隧道施工的影响较小；当 40 m时，建筑物的存在对隧道施工的影响可以忽略不计。由于基础的存在，建筑物的最大弯矩、轴力和剪力的变化量较小，增大量在10 %以内。

Numerical simulation of underground excavated tunnel construction of adjacent structure

Tunnel construction with underground excavated method in soft soil often induces ground deformation. Due to that the city underground excavation tunnel lies in area with dense and intensive buildings, the damage of soil deformation to adjacent structure is noticeable. 2D FEM is adopted to study and simulate the underground excavated tunnel construction of adjacent structure. The building is with length of 15m. It is indicated as follows. Surface settlement together with force and deformation of the lining are increased by the existence of building; simultaneously, additional stress and deformation of adjacent structure are induced during tunnel excavation construction. L is defined as horizontal distance from tunnel axis to building axis. When 0 m, the building is relative secure. When , the building incline to sides of tunnel. When to 20 m, great surface settlement is produced with more settlement difference between building head and tail; and the building is in danger. When to 40 m, the impact of building on the tunnel construction is small. When 40 m, the influence of building on the tunnel construction is negligible. As a result of the foundation, the maximum of bending moment, the axial force and the shearing force vary little; with extends range is less than 10 %.