承压水层基坑开挖对紧邻既有车站的影响研究

Study on the Influence of Foundation Pit Excavation in Confined Water on Adjacent Existing Station

结合北京市地铁17号线新建次渠站工程,从北京地区地下承压水的分布情况出发,采取文献调研、理论分析、数值模拟和现场实测等手段,对多层承压水地层新建车站施工引起邻近既有车站的变形进行了研究。基于现场实测数据分析了既有车站的变形,并建立了邻近既有车站基坑开挖仿真模型,分析了承压水地层基坑开挖对既有车站的变形影响。采用控制变量的方法分析了基坑开挖和承压水引起既有车站上浮的原因,总结了既有车站上浮超限的原因,并将数值模拟数据与实测数据进行了对比分析,验证了数值模拟数据的准确性。研究表明:既有车站的存在改变了土体变形,明显“阻碍”了基坑开挖后中部土体的应力传递,使中部土体变形滞后于两侧土体;多层承压水的存在是既有车站严重上浮的主要原因。

Based on Ciqu Zhan of Beijing Subway Line17,according to the distribution of underground pressure water,the deformations of adjacent existing stations caused by the construction of new station in multi-layer confined water strata were studied by means of literature research,theoretical analysis,numerical simulation and field testing.Based on the field measured data,the deformation of the existing station was analyzed.A simulation model was established for foundation pit exploration of the adjacent existing station to analyze the influence of foundation pit excavation.The control variable method is used to analyze the floating of existing stations caused by foundation pit excavation and pressurized water.The reasons for the overrun of the existing stations are summarized in this thesis.The numerical simulation calculation results are compared with monitoring data on-site to verift the accuracy.The study shows that the existing station has changed the soil deformation.It obviously hinders the stress transmission of the middle soil body after the foundation pit excavation,which makes the soil body in the middle behind the soil body on both sides;Multi-layer confined water is the main reason for the serious floating of existing station.