深基坑“降-隔-灌(水)”作用对运营地铁隧道的扰动效应研究

随着我国沿海(江)地区城市地下空间的建设越来越广泛，紧邻运营地铁隧道的深基坑开挖必将越来越频繁，而我国沿海(江)地区水文地质条件复杂，含水层厚度大，深基坑降水、竖向悬挂式帷幕隔水以及人工回灌等地下水控制措施经常被广泛应用到工程实践中。本项目围绕滨海软土地区深基坑“降-隔-灌(水)”作用对运营地铁隧道扰动效应问题，通过系统的理论和试验研究，探明深基坑“降-隔-灌(水)”作用下周围含水层渗流场动态演变机制，分析地下水位“下降-回升”动态变化对地铁盾构隧道的扰动效应与变形规律，明确地下水位变化对运营地铁盾构隧道扰动变形的影响，建立深基坑“降-隔-灌(水)”作用下地下水位变化引发运营地铁盾构隧道变形预测评估方法。研究成果可为我国滨海软土地区紧邻深基坑开挖下地铁盾构隧道运营安全评估与降-隔-灌(水)协同控制提供理论支撑。

With the urban underground space being built more and more widely in the coastal or riverside area of China, the excavation of deep foundation pits adjacent to metro tunnels will become more frequent. In coastal areas of China, the hydrogeological conditions are complex and the thickness of aquifers is also large. The groundwater control measures, such as excavation dewatering, partially penetrated waterproof curtain and artificial recharge, are often widely used in engineering practice. .Aiming at an issue on the disturbance effect of an operating subway shield tunnel due to the coupling effect of dewatering-waterproof curtains-recharge during a deep excavation in the coastal soft soil area, systematic theoretical and experimental research are conducted. The research contents of this project include illustrating the dynamic evolution mechanism of seepage field in surrounding aquifers due to the coupling effect of dewatering-waterproof curtains-recharge during a deep excavation, analyzing the disturbance effect and deformation law of a metro shield tunnel due to the dynamic change of groundwater level, addressing the influence of groundwater level change on disturbance deformation of a shield tunnel, and establishing a method for predicting and estimating the deformation of a metro shield tunnel induced by the change of groundwater level due to the effect of dewatering, waterproof curtains and recharge during a deep excavation..The research results can provide theoretical support for the safety assessment of an operational shield tunnel and cooperation control of dewatering, waterproof curtains and recharge during the excavation of an adjacent deep foundation pit.