增湿条件下膨胀土隧道近距离下穿既有地铁车站施工力学分析

为确保膨胀土地层渗水后,矿山法隧道近距离下穿既有地铁车站施工过程隧道及车站的安全,以合肥地铁5号线下穿既有车站隧道工程为依托,采用PLAXIS 3D岩土有限元软件精细化模拟整个施工过程,计算分析隧道、地层及既有车站结构的响应规律。研究结果表明:隧道下穿车站结构时经历的应力场较低;引起的地层变形主要表现为底部隆起和掌子面回弹变形;隧道下穿后,车站结构表现为中部隆起,前后两端沉降,施工时应控制既有车站的局部上浮。结合监测数据分析,表明隧道自身和既有车站基本处于安全稳定状态,施工方案合理可靠。

Analysis of construction mechanics of expansive soil tunnel passing through existing subway station in short distance under humidification condition

In order to ensure the safety of the existing structure and the construction of the expansion soil tunnel under the condition of water seepage, based on the existing station tunnel project of Hefei Metro Line 5, considering the expansion and contraction of the expansion soil and the bad characteristics of fissures, the PLAXIS 3D geotechnical finite element software was used to simulate the whole construction process, and the response law of the tunnel, stratum and the existing station structure was calculated and analyzed. The research shows that the stress field of the tunnel passing through the station structure is relatively low. The formation deformation caused by the tunnel is mainly manifested as the bottom uplift and the face rebound deformation. After the tunnel passing through, the station structure is manifested as the middle uplift, the front and rear ends settlement, and the local uplift of the existing station should be controlled during the construction. Combined with the monitoring data analysis, it shows that the tunnel itself and the existing station are basically in a safe and stable state, and the construction scheme is reasonable and reliable.