浅埋黄土地铁双连拱隧道施工引起地表沉降特征研究

以西安地铁4号线飞天路站到航天大道站区间双连拱隧道工程为例,通过FLAC3D软件模拟计算隧道两侧洞室采用CRD法(交叉中隔墙法)施工时各阶段地表沉降,并与现场监测数据进行对比。结果表明:两侧洞室施工引起地表沉降占总沉降的65%,上导洞施工引起地表沉降占该阶段总沉降的67%;控制上导洞施工引起的沉降是控制最终沉降的关键。中洞施工时,在监测断面前后1.5倍单个导洞宽度范围内地表沉降增长速率较大;两侧洞室施工时,在监测断面前后5倍单个导洞宽度范围内地表沉降增长速率较大。当施工到该范围内时,应及时进行初期支护并加强监测。

Surface Settlement Caused by Shallow Double-arch Tunnel Construction in Loess Land

Based on the double-arch tunnel project between Flying Road Station and Space Avenue Station on Xi'an metro Line 4,software FLAC3D is used to simulate the surface settlement during the construction stage when two side chambers are excavated by cross diaphragm (CRD) method,the calculated results are compared with the measured data for the interval.The result shows that the surface settlement caused by the excavation of the two side chambers accounts for 65％ of the total settlement,the top heading excavation accounts for 67％ of the total settlement.It is clear that the construction of the two side chambers of the top heading is the key to control the final surface settlement.The growth rate of surface settlement is larger in the monitoring section before and after 1.5 times of a single heading width range as the middle of the tunnel is excavated,in the monitoring section before and after 5 times of a single tunnel width range as the two side chambers are excavated.Therefore,the monitoring should be strengthened and the initial support be applied in time when the construction is carried out within the certain range.