软土地区基坑粉砂承压含水层抽灌试验  

Pumping and recharging tests in silty sand confined aquifer of foundation in soft soil area

作　　者：仲志武[1] ZHONG Zhiwu(China Railway 18th Bureau Group Co. Ltd., Tianjin 300222, China)

机构地区：[1]中铁十八局集团有限公司,天津300222

出　　处：《南京工业大学学报（自然科学版）》2022年第4期419-427,共9页Journal of Nanjing Tech University(Natural Science Edition)

基　　金：中国铁建股份有限公司科技研究开发计划(2020-C64)。

摘　　要：随着基坑工程逐渐向深、长、大方向发展,悬挂式止水帷幕应用越来越广泛。在复杂地质环境中,若承压含水层深厚,止水帷幕未能完全隔断基坑内外水力联系,则基坑内降水将导致坑外水位降低,进而容易引发周边建筑物沉降,需要采取回灌等措施进行保护。天津地铁6号线某地铁车站基坑工程场地承压含水层较厚,地连墙未截断承压水,且基坑南侧存在高层建筑群,需采取措施对建筑物进行保护。然而对于天津粉土粉砂承压含水层,回灌可行性和设计参数均需专项研究,因此在基坑施工前设计实施抽灌试验,探究基坑内外水力联系,研究场地回灌效果,获取场地水文参数,为降水和回灌方案设计提供理论支撑和依据。通过多组抽水及回灌试验数据分析得出:该场地承压含水层具备回灌可行性,采用回灌能够有效保护周边建筑物,采用加压回灌可以有效提高回灌效率,但回灌压力不宜超过0.14 MPa。试验成果可为本场地回灌井布设等方案设计提供依据,为软土地区粉土粉砂地层基坑回灌设计提供参考。With the gradual development of the deep and long foundation engineering,the application of suspended water proof curtain is more and more widely.In the complex geological environment,the confined aquifer is deep and thick,the water proof curtain fails to completely cut off the hydraulic connection between inside and outside of the foundation,and the dewatering inside the foundation will cause the water level outside the foundation to drop,which is easy to cause the surrounding building settlement.Thus,it is necessary to take some measures to protect.The confined aquifer in the foundation engineering site of a subway station on Tianjin Metro Line 6 was thick,the diaphragm wall didn't cut off the confined water,and there were high-rise buildings on the south side of the foundation.Measures should be taken to protect the buildings.However,for the silty sand confined aquifer in Tianjin,the feasibility and design parameters of recharging need special research.Therefore,before the excavation of the foundation,the pumping and grouting test was carried out to explore the hydraulic connection of the inside and outside of the foundation,and the effect of the recharging was tested.The site hydrological parameters were obtained,which provided theoretical support and basis for the design of precipitation and recharging scheme.Through the analysis of several groups of pumping test and recharging test data,it was concluded that the confined aquifer in the site was feasibility to recharge,which was suitable for the protection of surrounding buildings by means of recharging.Pressurized recharging could also improve the efficiency of the recharging,but the pressure value should not exceed 0.14 MPa.The test results provide a basis for the layout of the well,and a reference for the foundation recharging design in the silty sand confined aquifer in the soft soil area.

关 键 词：回灌试验 悬挂式止水帷幕 基坑降水 地表沉降 地下连续墙 

分 类 号：TU43[建筑科学—岩土工程]