开挖前降水引发基坑变形特性及控制方法

Characteristics of Foundation Pit Deformation Induced by Pre-excavation Dewatering and the Countermeasures

随着邻近已运营高铁、地铁的深基坑工程越来越多,准确预测基坑施工全过程引起的环境变形并进行毫米级的控制成为深基坑建设的重要需求和挑战。工程实测资料表明,开挖前降水引起的基坑变形即可达厘米级,并可导致已运营高铁、地铁的变形超过允许值。本文针对这一问题,结合已有文献分析,阐述了开挖前降水引发基坑变形的机理,总结了基坑宽度、降水深度、降水时间、土层渗透性等对降水引发基坑变形特性的影响规律,提出了降水井错位排布以控制开挖前降水引发基坑变形的方法,在此基础之上,对基坑开挖前降水引发变形问题的后续研究方向进行了探讨。

More and more excavations are adjacent to operating high-speed railway and subway.Predicting the environment deformation caused by the whole process of excavation construction,and controlling the deformation in millimeter level become the important requirement and challenge in excavation.Field measurement show that the deformation of retaining structure and surrounding environment induced by pre-excavation dewatering can reach centimeter level,which can lead the deformation of operating high-speed railway and subway exceed their allowable value.In this paper,the progress of research in deformation induced by pre-excavation dewatering are analyzed.The research results of the dewatering-induced deformation mechanism and deformation behavior are summarized.It is found that the foundation pit width,dewatering depth,dewatering time and soil permeability have great effect on the dewatering-induced pit deformation.Moreover,deformation control method staggered layout of dewatering wells is proposed.In the end,the existing problems and the future research direction in the topic of deformation induced by pre-excavation dewatering are discussed.