砂质地层下敞开式降承压水对车站基坑周边环境影响研究  

Research on the impact of open descending confined water under sandy stratum on the environment surrounding the foundation pit of metro station

作　　者：汪乐 张荣宽 WANG Le;ZHANG Rongkuan(China Design Group Co.,Ltd.,Nanjing Jiangsu 210014,China)

机构地区：[1]华设设计集团股份有限公司,江苏南京210014

出　　处：《现代城市轨道交通》2024年第11期60-65,共6页Modern Urban Transit

摘　　要：针对坑底存在深厚粉土粉砂地层的地铁车站深基坑,采用有限差分地下水流建模软件Modflow建立三维数值计算模型,结合现场抽水试验及基坑周边地表沉降的监测结果,研究由降承压水引起的承压含水层及上覆土层的沉降分布规律,以及由降承压水引起的坑外地表沉降大小的影响因素。研究表明,基于分层总和法得出的承压含水层上覆土层的沉降远小于总沉降量,由降承压水引起的坑外地表沉降约为承压含水层压缩量的0.04倍;止水帷幕插入承压水层深度大于50%时,增加单位长度的止水帷幕对减小坑外地表沉降更为有效;在敞开式降承压水情况下,增加承压水头降深比止水帷幕插入承压水层的长度变化对坑外地表沉降的影响更大。研究结论可为后续类似深厚粉土粉砂地层深基坑降水提供参考。Aiming at the deep foundation pit of metro station with deep and think chalky soil and sandy stratum at the bottom of the pit,the finite difference groundwater flow modeling software Modflow is used to establish a three-dimensional numerical computation model,and combined with the on-site pumping test and the monitoring results of the surface settlement around the foundation pit,the research is conducted to find out the distribution principle of the settlement of the confined aquifer and the overburden layer caused by the descending confined water and the influence of the size of the surface settlement outside the pit caused by the descending confined water.The research shows that the settlement of the overlying soil layer of the confined aquifer based on the layered sum method is much smaller than the total settlement,and the surface settlement outside the pit caused by the descending confined water is about 0.04 times of the compression amount of the confined aquifer;when the depth of the stop curtain inserted into the confined water layer is more than 50%,increasing the length of the stop curtain per unit is more effective in reducing the surface settlement outside the pit;in the case of open descending confined water,increasing the depth of the confined water head drop has a greater effect on the surface settlement outside the pit than the change in the length of the stop curtain inserted into the confined water layer.The conclusion of the research can provide a reference for the subsequent deep foundation pit descending in similar deep and thick chalky soil and sandy stratum.

关 键 词：地铁车站 基坑 粉土粉砂 承压水 地表沉降 

分 类 号：U231.1[交通运输工程—道路与铁道工程]