隧道穿越距离变化对地表框架结构变形的影响

为了研究隧道施工对邻近建筑物基础的沉降量、沉降差、扭转及倾斜等变形特征随隧道距离的变化规律,结合广州地铁隧道下穿一个框架结构建筑物,利用FLAC3D软件建立隧道-土-建筑结构的三维有限差分计算模型,考虑了建筑物的中间纵向框架与隧道轴线平行、距离从0m增加到20m共11种工况。根据计算结果,建筑物的最大扭曲变形量和最大沉降量随着距离的增大,都由最大值逐渐减小趋于零,其中最大扭曲变形量减小很快,当水平距离超出隧道轴线埋深时,扭曲变形量可以忽略不计;而建筑物倾斜、相邻基础的沉降差先由零逐渐增加,在沉降槽边缘内侧达到最大值,随后逐渐减小,最后逐渐趋于零。研究结果表明,对于受隧道施工影响的地表框架结构建筑物,在隧道上方位置时应重点监控其沉降量和扭转变形量,而在沉降槽边缘内侧时应注意监控其沉降差和倾斜量。

Influence on Deformations of a Ground Frame Structure by a Tunnel Crossing at Different Distances

A case of a frame building in Guangzhou was employed for investigating the effect of tunnel construction on adjacent buildings, including foundation total settlement, differential settlement, and building torsion and inclination. A tunnel-soil-structure numerical model was established by using the software FLAC3D, and a total of 11 cases were calculated with the building middle axis being parallel to the tunnel axis while their horizontal distance varying between 0 m and 20 m. The numerical results show that both the maximum foundation settlement and the maximum building torsion decrease from their maximum values to zero with the increase of the horizontal distance between the building and the tunnel. Meanwhile, the maximum building torsion decreases rapidly and becomes negligible when the horizontal distance is greater than the depth of the tunnel axis. However, the building inclination and the differential settlement of two adjacent footings increase initially, then reach their peak values at the inner edges of the settlement trough, and finally decrease to zero. The numerical results indicate that the footing settlement and building torsion, caused by tunnel construction, should be monitored for frame structure buildings located above the underground tunnel; in contrast, the building inclination and differential settlement should be monitored for those located at the edges of the settlement trough.