双侧深基坑施工对紧邻地铁隧道变形影响的分析

ANALYSIS OF INFLUENCE ON DEFORMATION OF ADJACENT SUBWAY TUNNEL DUE TO BILATERAL DEEP EXCAVATIONS

以广州某邻近地铁隧道的基坑工程为背景,运用Midas/GTS建立三维数值模型,通过数值模拟结果与实测数据的对比分析及数值试验等手段,分析双侧深基坑按不同顺序开挖对穿越其间的已运营地铁隧道的影响。结果表明:计算结果与工程实测数据基本吻合;两基坑对称开挖比不对称开挖能更好地控制隧道水平位移,但对称开挖对于隧道竖向位移的控制相对不利。提出并验证在水平面内为曲线形状的隧道,由于曲线隧道内侧与外侧的纵向刚度不同,在其他条件相同的情况下,在曲线隧道凸出侧的卸载比在其凹进一侧卸载对隧道的影响更大。

According to the practice of deep excavation adjacent to subway tunnel in Guangzhou, the finite element software Midas/GTS is employed to establish a 3D numerical model to simulate and analyze the interactive impact on the crossing tunnel caused by different construction sequences of the adjacent deep excavations on both sides of the tunnel. A comparative analysis is also made between the measured data and the results of finite element method. The calculated results are good agreement with the field measurements. The two results show that symmetric excavation method is better than asymmetric excavation method in controlling the horizontal displacement of the tunnel： however, symmetric excavation method is not suitable for controlling the vertical displacement of the tunnel. A conclusion is proposed and verified by numerical experiment that the effect on the curved tunnel in the horizontal plane caused by unload on the convex side of the curved tunnel is more serious than that by unload on the concave side of the curved tunnel under the same condition, because the longitudinal stiffness is different in two sides of the curved tunnel.