高水位深基坑渗漏及立柱桩沉降原因分析与处理

Analysis and Treatment of Leakage and Settlement of Column Pile in Deep Foundation Pit with High Water Level

江东大道提升改造工程青六路~青东一路隧道长853m,采用明挖顺作法施工。工程区以粉砂夹砂质粉土地层为主,地下水位高,基坑采用排桩支护,辅以三轴搅拌桩止水帷幕。由于基坑开挖卸荷,基坑内外土体应力重分布,以及基坑渗漏、开挖时间过长、钢支撑架设不规范等原因引起立柱桩沉降变形值报警,威胁到基坑施工安全。结合施工监测数据,对基坑渗漏及立柱桩沉降变形监测值其报警值的原因进行分析,提出了处理措施,并在工程中成功应用。

The tunnel of Qing 6 Road to Qingdong 1 Road of Jiangdong Avenue Lifting and Reconstruction Project is 853m long and constructed by open-excavation and sequential construction method.The project area is mainly composed of silty sandy silt layer with high groundwater level.The foundation pit is supported by row piles and assisted by three-axle mixing pile water-stop curtain.Due to unloading during excavation of foundation pit,redistribution of stress in soil mass inside and outside of foundation pit,leakage of foundation pit,long excavation time,irregular erection of steel support and other reasons,alarm of settlement and deformation value of pillar pile is caused,which threatens the safety of foundation pit construction.In combination with construction monitoring data,this paper analyses the causes of alarm values of monitoring values for foundation pit leakage and column pile settlement and deformation,and puts forward treatment measures,which have been successfully applied in the project.