富水流塑软硬复合地层下地铁盾构隧道施工稳定性分析

Analysis of Shield Tunnel Construction Stability in Wate-rich Flow Plastic Soft-hard Composite Stratum

以长沙轨道交通3号线一期工程地铁盾构隧道侧穿浏阳河大堤为工程背景,研究渗流作用下盾构隧道开挖对地表、地层及河堤变形的影响,进而提出变形控制方案,并通过实测数据对模拟结果进行验证。研究结果表明:由地下水上浮作用产生的隧道洞周围岩的竖向位移值占总位移值的20%~30%,在实际工程中该因素对隧道洞周围岩位移的影响不可忽略;未采取加固措施时,流固耦合效应下地表沉降不符合规范要求,提出三重管旋喷桩加固地层方案;采取加固措施后,通过对比发现未考虑流固耦合时隧道各关键部位的沉降值误差比考虑流固耦合时要大,这说明将考虑流固耦合效应的数值模拟作为隧道正式施工前的稳定性分析依据更加合理。

The first phase of shield tunnel on Changsha rail transit Line 3 engineering is taken as the background, which crosses through the side of Liuyang River Levee, the influence of shield tunnel excavation on the deformation of surface, strata and river levee under seepage is studied, a deformation control scheme is put forward. The simulation results are verified by the measured data, which show that the vertical displacement caused by groundwater floatation accounts for about 20%~30% of the total displacement value, the influence of this factor on rock displacement around tunnel can not be ignored. In practical engineering, the surface settlement under fluid-solid coupling effect is not in accordance with the standard value when reinforcement measures are not taken, therefore the scheme of strengthening strata with triple pipe jet grouting pile is put forward. After reinforcement, it is found that the settlement error of each special position without considering the fluid-solid coupling is larger than that considering the fluid-solid coupling, indicating that the numerical simulation that takes the fluid-solid coupling effect as the basis of stability analysis before the tunnel formal construction is more reasonable.