既有地下人防洞库对基坑变形的影响分析

为了深入研究既有人防洞库对基坑变形的影响情况，运用 PLAXIS有限元程序对开挖进行模拟，得到在基坑开挖过程中，既有人防结构对基坑周边位移场、沉降变形及坑底土体隆起变形情况的影响。模拟计算结果表明，在相对于无人防洞库基坑开挖情况下，基坑开挖到人防结构时，基坑支护结构周围沉降变形模式明显改变，同时最大沉降有少许降低，而最终隆起量降低明显。人防洞库的存在对基坑变形有明显的限制作用，这种作用主要是限制坑底隆起，从而影响周围沉降。同时，总结出了基坑开挖地层变形的基本规律，为今后类似工程提供有益的参考。

A Finite Element Analysis of the Effect of the Existing Civil Air Defense Shelters on the Stratum Deformation of Foundation Pits

In order to make a deep study of the effects of the existing air defense shelters on the deformation of the foundation pit,the excavation for the foundation pit is simulated with the help of the finite element program PLAXIS,with the effects of the existing air defense shelters on the displacement of the displaced fields around the foundation pit,the settlement and deformation,and the uplifting of the soil at the bottom of the foundation pit.The simulated and calculated results show that,compared with the excavation in the place where there is no air defense shelter,the modes of the settlement and deformation of the stratum near the supporting structures of the foundation pit change obviously when the excavation for the foundation pit reaches an air defense shelter,with the maximum settlement a bit decreased while the final uplifting amount remarkably decreases.The existence of air defense shelters has an obvious limiting effect on the deformation of the foundation pit and the effect chiefly takes the form of restricting the bottom bulge of the foundation pit,thus affecting the surrounding settlement.The basic laws of the stratum deformation resulting from the excavation for foundation pits are summed up in the paper,which may provide a useful reference for the construction of similar proj ects in the future.