坑内隔墙高度对基坑挖前抽水测试引发围挡偏转的影响  

EFFECT OF CROSS WALL HEIGHT ON ENCLOSURE WALL DEFLECTION INCURRED BY PUMPING TEST BEFORE BULK EXCAVATION

作　　者：薛秀丽[1] 杨瑶 曾超峰[1] 李淼坤 陈秋南[1] 龙四春[2] 罗桂军 XUE Xiuli;YANG Yao;ZENG Chaofeng;LI Miaokun;CHEN Qiunan;LONG Sichun;LUO Guijun(Hunan Provincial Key Laboratory of Geotechnical Engineering for Stability Control and Health Monitoring,Hunan University of Science and Technology,Xiangtan 411201,China;School of Earth Science and Space Information Engineering,Hunan University of Science and Technology,Xiangtan 411201,China;China Construction Fifth Engineering Division Co.,Ltd.,Changsha 410011,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,中国湘潭411201 [2]湖南科技大学,地球科学与空间信息工程学院,中国湘潭411201 [3]中国建筑第五工程局有限公司,中国长沙410011

出　　处：《工程地质学报》2023年第5期1719-1727,共9页Journal of Engineering Geology

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

摘　　要：基坑挖前抽水可诱发明显围挡变形,而常用的墙顶支撑方案尚不能很好地防控围挡深部位置变形。近期,有学者针对软土地区基坑施工常用的“坑内布设隔墙的分区段施做方法”,提出了“考虑隔墙支护效应”及“优化布置隔墙”的变形防控理念,实现了基坑挖前抽水引发变形的有效控制。为进一步优化坑内隔墙的布置,本文开展了隔墙高度对挖前抽水引发变形的影响研究。针对某具体基坑工程,通过一系列数值分析,探究了在不同抽水深度、隔墙高度条件下挖前抽水引发的基坑围挡变形特性,并基此提出了隔墙在深度方向的优化布置方案。研究表明,隔墙在深度方向的布置范围对其变形控制效果有很大影响,具体地,在降水深度范围内布设隔墙可显著减小抽水引发的围挡侧移,而降水深度以下的隔墙布设对围护结构侧移的控制作用十分有限。为兼顾经济性与变形控制效果,建议将隔墙顶面设置在降水深度(H_(d))以上0.33~0.67 H_(d)位置处,隔墙底面设置在H_(d)处;但当坑外存在对变形敏感的深埋结构时,可将隔墙底面进一步向下延伸1/3 H_(f)(H_(f)为降水深度至围护结构底面距离)以达到控制深埋结构变形的目的。Dewatering before bulk excavation is able to cause centimeter-level wall deflection,while the commonly-used inner strut system cannot effectively limit the wall deflection at deep location.Recently,aiming at the inner cross-wall system frequently used to achieve sectionalized construction in soft soil area,some scholars proposed a deformation-control idea of making use of cross wall and optimizing its layout,which effectively restricts the dewatering-induced deformation.This paper aims to further optimize the arrangement of the cross wall to ensure the deformation control effect under the most economical conditions.It investigates the influence of cross wall height on the enclosure wall deflection incurred by dewatering before bulk excavation.Based on an actual foundation pit,a series of numerical simulations are conducted to explore the deformation characteristics of enclosure wall incurred by dewatering before bulk excavation under different pumping depths and cross wall height.On this basis,this paper proposes the optimized layout of cross wall in depth direction.Results show that the layout of cross wall in depth direction has a great influence on its deformation control effect.Specifically,the installation of cross wall within the pumping depth can significantly reduce the retaining wall deflection triggered by pumping,while the installation of cross wall below the pumping depth has a very limited effect on the control of retaining wall deformation.In order to take into account both the economy and deformation control effect,this paper recommends to set the cross wall top at 0.33-0.67 H_(d) above the pumping depth(H_(d))and set the cross wall bottom at H_(d).When there are deeply-buried structures outside the pit which are sensitive to deformation,it should be better to extend the cross wall bottom downward by 1/3 H_(f) to achieve the deformation control of deeply buried structures,where H_(f) is the distance between the pumping depth location to the retaining wall bottom.

关 键 词：软土 基坑抽水 隔墙 数值分析 围护结构侧移 

分 类 号：TU473[建筑科学—结构工程]