富水砂层深基坑变形稳定可控是地下工程施工安全的基础保障。针对富水砂层深基坑渗漏灾害问题，以某地铁车站端头井深基坑渗漏事故为研究背景，通过现场调查和实测数据回顾，总结分析基坑漏水漏砂灾害发展过程及事故原因，系统研究基坑渗漏水期间挡墙水平位移、墙后地表沉降、坑外地下水位的变化特征，并结合数值模拟方法揭示局部渗漏对基坑变形性状的影响规律。研究结果表明，局部渗漏引起挡墙水平位移显著增加，渗漏后挡墙最大水平位移约为渗漏前的1.29~1.47倍；局部渗漏引起敏感影响区沉降槽加深变宽，渗漏后最大地表沉降约为渗漏前的1.16~2.67倍；坑外地下水位“跳跃式”波动变化特征可作为基坑发生渗漏灾害前兆信号的重要判据；采取“注浆+高压旋喷桩”联合处治措施可有效应对富水砂层基基坑渗漏灾害控制难题。

The stable and controllable deformation of deep foundation pit in water-rich sandy strata was the basic guarantee of underground engineering construction safety. Aiming at the leakage disaster of deep foundation pit in water-rich sandy strata, this paper takes the leakage incidents of launch shaft pit of subway station as the research background, summarizes and analyzes the development process and accident causes of water and sand leakage disaster through field investigation and survey data review, the characteristics of horizontal displacement of retaining wall, ground settlement behind wall and change of groundwater level outside the pit during partial leakage were systematically studied, and the effect rules of partial leakage on the deformation behavior of foundation pit were revealed by numerical simulation method. The results of research shows that the horizontal displacement of the retaining wall increases significantly due to partial leakage, and the maximum horizontal displacement of retaining wall after leakage is 1.29 to 1.47 times that before leakage. The ground settlement trough of sensitive zone deepens and widens due to partial leakage, and the maximum ground settlement after leakage is 1.16 to 2.67 times of that before leakage. The characteristics of "jump" fluctuation of groundwater level can be used as an important criterion for the precursor of leakage disaster in foundation pit. The combined treatment measures of grouting and high pressure rotating spouting pile can effectively deal with the problem of leakage disaster control of foundation pit in water-rich sandy strata.