基坑开挖引起紧邻地铁隧道力学响应与处理方案研究

Research on mechanical response and countermeasures of subway tunnel induced by adjacent excavation

针对在建基坑对既有地铁隧道影响问题,依托杭州某基坑工程,建立三维数值仿真模型,分析既有地铁隧道在基坑施工中的受力变形响应,重点评价基坑施工引起隧道结构的附加应力及变形,在此基础上,研究临近隧道侧围护结构参数加强、分块对称开挖等措施对隧道结构受力变形的控制效果。研究结果表明:基坑开挖对临近既有隧道的影响程度与两者之间的距离、基坑支护结构刚度及开挖顺序有关,距离越近、支护刚度越小、一次开挖范围越大影响越大;加强临近隧道侧围护结构刚度和合理采用分块对称开挖均能很好地控制基坑变形,尤其适用于变形控制严格的工程;除附加变形外,隧道结构附加内力可作为隧道结构稳定分析的重要评价指标。

In order to analyze the impact of the construction of foundation pit on existing shield tunnel,a three-dimensional numerical simulation model which relies on a foundation pit engineering in Hangzhou is established to study the deformation of existing shield tunnel due to the construction of foundation pit.This paper focuses on the additional stress and the deformation of shield tunnel structure caused by the construction of foundation pit.The control effects of several measures,such as symmetric block excavating and strengthening the parameters of exterior-protected construction adjacent to the side of tunnel,on shield tunnel's deformation were researched.The results show that,the additional internal forces in tunnel structure can be used as an important evaluation index of tunnel structure stability analysis,except for additional deformation.It can well control pit deformation to strengthen the stiffness of exterior-protected construction adjacent to the side of tunnel and rational use symmetric block excavating.These measures is particularly suitable for engineering of rigorous deformation control.