深基坑施工对共用围护结构运营车站的变形影响

Influence of Deep Foundation Pit Construction on Deformation of Operating Station Sharing Enclosing Structure

依托成都地铁新建18号线倪家桥站与运营1号线车站超近接并行、共用1号线既有围护桩、深基坑采用半盖挖法施工的工程实例,采用数值模拟将围护桩等效为地下连续墙,分析不同围护桩桩径、内支撑数量下,深基坑开挖对运营地铁车站的变形影响。结果表明:基坑开挖卸荷使土体发生变位,带动车站结构产生位移,体现为竖向隆起,横向偏向基坑开挖侧;增大地下连续墙厚度可减小运营车站的变形,但当厚度大于0.76 m时,控制变形效果不明显;当支撑大于2道时,抑制侧墙水平位移和地表沉降的效果不明显。

Based on project example that the Nijiaqiao station of Chengdu Metro newly-built Line 18 is super close and parallel to the station of Line 1,sharing the existing retaining pile of Line 1,and the deep foundation pit is constructed by half-cover excavation method,using the numerical simulation,the retaining pile is equivalent to the diaphragm wall and the influence of deep foundation pit excavation on the deformation of existing subway stations under different pile diameters and the number of inner supporting layers is analyzed.The results show that the excavation unloading of the foundation pit causes the soil to be displaced and drives the displacement of the subway structure in the soil,which is reflected in the vertical uplift and the lateral deviation to the excavation side of the foundation pit.Increasing the thickness of the diaphragm wall can reduce the deformation of the existing station,but the thickness of the diaphragm wall is greater than 0.76 m,the effect of controlling deformation is not obvious.When the number of support layers is more than 2 layers,the effect of inhibiting the horizontal displacement of the side wall and the surface settlement is not obvious.