地铁施工中车站之间密贴下穿风险及控制措施

Risk and control measures of the closely-attached undercrossing of station during subway construction

新建车站密贴下穿既有车站暗挖工程施工风险大,既有车站沉降控制要求高,因此有必要对车站之间密贴下穿工程中的风险进行分析,提出变形控制措施。本文以北京地铁6号线苹果园站新建车站密贴下穿既有车站实际工程为例,分析新建车站密贴下穿既有车站工程风险;提出在PBA工法施工基础上采取控制措施减小既有车站沉降,达到工程沉降控制要求。控制措施包括:1)PBA工法导洞开挖前分区域深孔注浆加固导洞周围地层;2)既有车站监测数据中部分监测点的沉降累计数值接近预警值时采用注浆抬升工艺控制既有车站沉降;3)下穿段中,与既有车站重复区域采用丝杠支顶工艺。最终通过监控数据进行验证,得出PBA工法结合以上沉降控制措施进行密贴下穿工程施工能够起到良好的沉降控制效果。

The construction risk of new station closely undercrossing existing station is greater, and the settlement control requirements of existing stations are higher.Therefore, it is necessary to analyze the risk in the project and put forward the deformation control measures.Taking the actual project of the new station of Pingguoyuan station of Beijing metro line 6 as an example, the project risk of the new station closely under crossing existing station is analyzed.Furthermore, the suggestion is proposed that control measures should be taken to reduce the settlement of existing stations on the basis of PBA construction method to meet the requirements of project settlement control.The control measures include: 1) Before the pilot tunnel excavation using PBA method, the strata around the pilot tunnel are reinforced by deep hole grouting in different areas;2) When the accumulated settlement value of some monitoring points in the monitoring data of the existing station is close to the warning value, the grouting lifting process is used to control the settlement of the existing station;3) In the down-passing section, the lead screw support technology is adopted in the repeated area with the existing station.Finally, through monitoring data verification, it is concluded that PBA construction method combined with the above settlement control measures can play a good settlement control effect in the construction of close-sticking underpass project.