考虑既有地铁车站阻隔效应的基坑抽水致沉模型试验研究  

Laboratory-scale model test on settlement incurred by foundation pit dewatering considering the barrier effect of pre-existing metro station

作　　者：曾超峰[1,2] 蔡钢 朱龙 张祖浩 陈宏波 薛秀丽[2] 龙四春[3] 罗桂军 ZENG Chaofeng;CAI Gang;ZHU Long;ZHANG Zuhao;CHEN Hongbo;XUE Xiuli;LONG Sichun;LUO Guijun(Hunan Provincial Key Laboratory of Geotechnical Engineering for Stability Control and Health Monitoring,Hunan University of Science and Technology,Xiangtan,Hunan 411201,China;School of Civil Engineering,Hunan University of Science and Technology,Xiangtan,Hunan 411201,China;School of Earth Science and Space Information Engineering,Hunan University of Science and Technology,Xiangtan,Hunan 411201,China;China Construction Fifih Engineering Division Co.,Ltd.,Changsha,Hunan 41001l,China)

机构地区：[1]湖南科技大学岩土工程稳定控制与健康监测湖南省重点实验室,湖南湘潭411201 [2]湖南科技大学土木工程学院,湖南湘潭411201 [3]湖南科技大学地球科学与空间信息工程学院,湖南湘潭411201 [4]中国建筑第五工程局有限公司,湖南长沙410011

出　　处：《岩石力学与工程学报》2023年第10期2566-2577,共12页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51978261);湖南省自然科学基金资助项目(2022JJ20023);湖南省科技创新计划项目(2022RC1172)。

摘　　要：城市既有地下结构可对地下水运动和土体运移产生阻隔效应,已有研究表明该阻隔效应或加剧、或减小抽水沉陷,而具体的规律与地下结构类型及其分布和所在位置有关。以坑外已有地铁车站结构的阻隔效应为例开展室内模型试验研究,通过在基坑-地层-车站结构物理模型中安装变形与应力传感器,全过程实时监控该条件下基坑抽水引起的坑外水位与水头变化、地面沉降、围挡侧移及其两侧水/土压力变化等,并将所有监测结果与同样抽水条件下坑外无地铁车站的模型试验结果进行对比,揭示地铁车站结构阻隔效应对基坑抽水致沉的影响机制。研究表明:在同样的基坑抽水设置和操作下,有阻隔效应时的基坑涌水量更小、坑内外最大水位降深和坑外地面沉降更大、围挡侧移更小。基坑设计中可考虑阻隔效应的影响而适当减少坑内抽水井数量以实现同样的基坑抽水效果,并应评估阻隔效应对基坑变形的影响从而得到更合理的基坑支护设计。In urban environment,the existing underground structures could exert a barrier effect on groundwater seepage and soil movement.According to current research results,this barrier effect would either aggravate or diminish the ground settlement,while the specific characteristics of ground deformation is associated with the types and spatial distribution of the underground structures.In this paper,laboratory-scale model tests were conducted to investigate the mechanism of dewatering-induced deformations when a foundation pit is adjacent to a pre-existing metro station.With installing deformation and stress sensors in the physical model of pit-strata-station,the variations of groundwater level outside the pit,ground surface settlements,wall deflections and lateral pressure on both sides of the enclosure wall were monitored in real time during dewatering.All the monitored results were compared with those from another model test without a subway station outside the pit under the same pumping conditions;based on the comparison,the impact mechanism of the barrier effect incurred by metro station on the dewatering-induced foundation pit deformation is revealed.Results show that as to the case with metro station outside the pit,the same dewatering operation as the case without metro station would induce smaller water yield of the pit,smaller enclosure wall deflection but greater ground surface settlement and greater groundwater drawdown on both sides of the enclosure wall.In foundation pit design,engineers could consider reducing the number of pumping wells to achieve the same pumping effect,and should evaluate the barrier effect of adjacent underground structures on foundation pit deformation to provide a more reasonable supporting scheme.

关 键 词：基坑工程 基坑降水 阻隔效应 地铁车站 水位降深 基坑变形 模型试验 

分 类 号：TU476[建筑科学—结构工程]