大型基坑开挖对邻近隧道的影响分析

Analysis of influence of large-scale foundation pit excavation on adjacent tunnels

结合软土地基某邻近地铁盾构隧道大型基坑开挖的工程背景,充分调研了邻近类似工程案例的围护结构设计方案及控制效果,阐述了邻近地铁隧道大型基坑工程围护结构的设计方案,并介绍了利用分坑开挖以减小开挖面积的开挖方式控制邻近盾构隧道的附加变形。采用Plaxis 3D进行建模分析,验证了大型基坑工程围护结构方案的合理性,并对各个开挖工况下坑外土体和隧道的变形进行分析,结果表明,基坑开挖范围的增加会扩大隧道附加变形的范围,距离隧道较远的基坑开挖对隧道附加变形的影响较小,数值模拟结果及实测数据均表明隧道附加变形控制在规范要求的合理范围之内。因此,此基坑围护结构方案是合理可行的,可供类似条件下的基坑工程借鉴参考。

Combined with the engineering background of the excavation of a large foundation pit near a subway shield tunnel on soft soil foundation,the design scheme and control effect of the retaining structure of the adjacent similar engineering cases were investigated.The design scheme of the retaining structure of the large-scale foundation pit project adjacent to the subway tunnel is expounded.The excavation method of using split pit excavation to reduce the excavation area to control the additional deformation of the adjacent shield tunnel is also introduced.Plaxis 3D was used for modeling and analysis,which verified the rationality of the retaining scheme of large-scale foundation pit engineering,and analyzed the deformation of soil and tunnel outside the pit under various excavation conditions.The results show that the increase of the excavation range of the foundation pit will expand the range of the additional deformation of the tunnel.The numerical simulation results and the measured data show that the additional deformation of the tunnel is controlled within a reasonable range required by the specification.Therefore the schematic design of the support forms is reasonable and feasible,and it can be used as a reference for foundation pit under similar conditions.