北京地铁洞桩法车站地表沉降变位控制分析

Deformation distribution control of ground settlement for cavern-pile station in Beijing metro

以北京地铁6号线洞桩法车站为工程背景,首先在现场实测数据分析的基础上对北京地区暗挖车站地表沉降值进行预测;然后选取Cam-clay(修正剑桥模型)对北京地区洞桩法地铁车站地表沉降规律进行分析;最后基于变位分配法对洞桩法地表沉降的位移控制进行分阶段处理,实现地表沉降分阶段控制的目标.结果表明:北京地铁6号线洞桩法车站地层损失率V1均小于1%,地表沉降槽宽度参数K为0.65~0.8;小导洞开挖(施工步序1)和二衬扣拱施作(施工步序3)引发的地表沉降所占比例之和近80%,施工步序1、3对控制地表沉降具有重要意义;现场实测和数值计算的结果基本吻合,地表沉降最大值均出现在车站中心线上方.

Cavern-pile stations of Beijing 6th line metro were taken as project background in this paper,the ground surface settlement prediction was performed by site measured data of mined metro station in Beijing area.Firstly,the ground surface settlement regularity was analyzed by Cam-clay model.Then,the settlement control of cavern-pile station was performed in every construction sequence based on deformation distribution method.The results show as follows:The stratum loss ratio V1 of cavern-pile station is less than 1%,and the settlement trough width parameter Kranges between 0.65~0.8.The proportion of ground surface settlement is approximately 80%induced by pilot excavation(construction sequence 1)and arch support in second lining stage(construction sequence3),thus construction sequence1and3 are vital to the control of ground surface settlement.The measured value of ground surface settlement basically agrees with the calculated,and the maximum value appears above station center line.