摘要
基坑止水帷幕渗漏问题影响着基坑的稳定和安全,因此开挖前的渗漏检测至关重要。利用抽水试验进行地连墙渗漏检验是一个经济有效的方法,但很少有学者对此进行深入系统研究,限制了此方法的发展与推广。本文通过对粉土层和黏土层地连墙出现不同大小裂缝时的抽水试验进行数值模拟,揭示了基坑发生渗漏时坑外水位与渗流场发展在空间和时间上的变化,并对基于坑外水位变化的基坑止水帷幕渗漏检测方法与布井原则进行了研究。主要结论如下:地连墙在粉土层发生渗漏后,坑外水位下降很快,短时间内(1d左右)即可达到稳定状态;坑外水位下降随渗漏面积增大而增大,但增大速率随面积增大而减小;在黏土层发生渗漏,水位下降远小于粉土层中情况,且稳定时间较长(约15d)。基于渗流场规律研究,提出了检测基坑渗漏时观测井布井原则,即观测井应靠近地连墙,利用降深随渗漏距离变化曲线及最小井内水位观测精度选取最大井间距,并且对基坑角部适当加密布井。基坑发生渗漏时,可根据两口水位下降最大的井的水位变化比例确定渗漏位置。本文提出的基于坑外水位变化的基坑止水帷幕渗漏检测布井原则与渗漏位置确定方法,有助于基于抽水试验地连墙渗漏检验方法的推广与应用。
Diaphragm wall is widely used in foundation pit engineering, and its leakage affects the stability and safety of foundation pit. By studying the fluid structure coupling, this paper analyzes the development status of foundation pit leakage, summarizes the causes of diaphragm wall leakage, introduces the common detection methods, and analyzes the advantages and disadvantages of various methods. Through the numerical simulation of the development of the water level outside the pit when there are different cracks in the ground connecting wall of silt layer and clay layer, the law of the change of the water level when the leakage occurs in the foundation pit and the change of the development of the seepage field in space and time when the leakage occurs in different soil layers are revealed. The following conclusions are drawn: in the initial stage of the leakage of silt layer, the water level drops rapidly and basically reaches a stable state in a short time;The drop of water level outside the pit increases with the increase of leakage area, which is basically linear, but the increase amplitude decreases with the increase of area. The drop of water level caused by the same leakage area in silt layer is much greater than that in clay layer;The water level of the observation well decreases with the increase of the distance from the leakage point. In the clay layer, leakage can hardly develop in space. Leakage of clay layer or small area leakage of silt layer has little impact on the project. Finally, the well layout principle of observation logging when detecting the leakage of foundation pit and the method of determining the leakage position by using the water level of dewatering well are put forward, which provides a reference for judging the location of leakage in engineering in the future.
作者
郭景琢
崔肇琳
吴天凯
李钟顺
栗晴瀚
程雪松
GUO Jingzhuo;CUI Zhaolin;WU Tiankai;LI Zhongshun;LI Qinghan;CHENG Xuesong(China construction infrastructure Co.,Ltd.,Beijing 100044,China;School of architectural engineering,Tianjin University,Tianjin 300350,China)
出处
《建筑结构》
CSCD
北大核心
2022年第S02期2443-2450,共8页
Building Structure
基金
中建基础科技研发课题(CSCIC-2020-KT-(01))
中建股份科技研发计划资助(CSCEC-2021-Z-(25))
关键词
降水井原理
地下连续墙
渗漏
检测
principle of dewatering well
diaphragm wall
leakage
detection
