新建通道密贴下穿地铁车站施工影响范围研究

Construction influence range of a new passageway closely undercrossing a subway station

该文依托新建成都地铁8号线倪家桥站换乘通道密贴下穿既有1号线车站工程,采用数值模拟和现场监测手段,对既有地铁车站受密贴下穿通道施工的影响范围开展研究。主要取得如下结论:(1)从既有车站底板沉降指标来看,受下穿通道分部开挖的施工过程影响,沉降曲线形态并不对称。沉降影响范围和沉降量值均随开挖区域的增大而增大;(2)从既有车站的柱子轴向应变增量指标来看,距开挖导洞最近的柱子应变增量最大,且为拉应变增量(即压应变减小);其余柱子总体上表现为距离越远,应变增量越小,且均为压应变增量;站台层柱子应变增量普遍较站厅层的柱子更大;(3)新建下穿通道施工对既有车站的影响范围随开挖区域的增加而增大,最终影响范围约49m,即新建通道左、右边界各外延约13m。上述研究成果可为今后类似工程提供参考。

This paper examines the newly built Nijiaqiao Station transfer channel of the Chengdu Metro Line 8 undercrossing the existing Line 1 station at zero distance.The influence range of the existing Line 1 station under the condition of underpass zero-distance tunneling is studied via numerical simulations and on-site monitoring.The main conclusions are as follows.(1)The settlement index of the floor of the existing station,as affected by the construction process of the underpass sequence excavation,indicates that the settlement trough is not symmetric.The influence range and the settlement values increase with increasing excavation area.(2)The axial strain increment index of the columns in the existing station indicate that the column closest to the excavation pilot tunnel has the largest strain increment,which it is a tensile strain increment,i.e.,the compressive strain decreases.Overall,columns with greater distances from the tunnel have smaller strain increments,all of which present compressive strain increments.The strain increments of the columns in lower floors are generally larger than those in upper floors.(3)The influence range of the existing station caused by the underpass tunneling increases with the excavation area.The final influence range of the existing subway station under the condition of underpass zero-distance tunneling is approximately 49 m,that is,it extends outward from the left and right boundaries of the newly built channel by approximately 13 m.These findings can be used as a reference for similar projects in the future.