非平衡建筑超载下软弱地层地铁深基坑变形特性及加固方案研究  

Research on deformation characteristics and reinforcement schemes of subway deep foundation pits in weak strata under unbalanced building overload

作　　者：李辉[1] 杨江峰 许良全 Li Hui;Yang Jiangfeng;Xu Liangquan(China Railway Eryuan Engineering Group Co.,Ltd.,Chengdu 610000,China;The 3th Engineering Co.,Ltd.,Second Public Bureau of China Communications,Xi’an 710016,China;China Construction Eighth Engineering Bureau Co.,Ltd.,Shanghai 200135,China)

机构地区：[1]中铁二院工程集团有限责任公司,成都610000 [2]中交二公局第三工程有限公司,西安710016 [3]中国建筑第八工程局有限公司,上海200135

出　　处：《工程勘察》2025年第2期1-8,43,共9页Geotechnical Investigation & Surveying

基　　金：国家自然科学基金(51808490).

摘　　要：软弱地层中某地铁深基坑外侧作用有建筑物偏压超载,对深基坑开挖存在较为不利影响。为研究外部建筑物偏压超载对软弱地层中基坑支护结构的变形影响,确定合理的隔离桩及基底加固方案,采用有限元方法进行了不同加固方案下基坑开挖模拟计算,并与实测结果对比分析。结果表明:临近深基坑的外部建筑物超载将对基坑支护结构产生明显的偏压效应,偏压超载对坑底软弱地层范围内支护结构影响最为明显;基坑外侧设置隔离桩加固,可有效减小地下连续墙水平位移,隔离桩变形在软弱地层范围最大,增加桩长可使桩底产生支点约束效应,但不能有效减小支护结构位移及支撑轴力;同样,改变隔离桩刚度对支护结构位移及支撑轴力影响较小;仅采用基底加固方案,可减小坑底范围内支护结构位移,但对上部支护结构变形影响较小,采用隔离桩+基底加固组合方案可有效减小支护结构变形及支撑轴力,降低了偏压荷载对基坑的不利影响,具有较好的加固效果。There is a building bias and overload on the outer side of a subway deep foundation pit in weak strata,which has a relatively adverse effect on the excavation of the deep foundation pit.To study the deformation effect of external building bias and overload on foundation pit support structures in weak strata,and to determine a reasonable isolation piles and foundation reinforcement schemes,finite element method is used to simulate excavation of foundation pits under different reinforcement schemes,and the results are compared and analyzed with actual measurements.The results indicate that the overloading of external buildings near deep foundation pits will have a significant bias effect on the support structure of the pit,with the bias overload having the most significant impact on the support structure within the weak strata at the bottom of the pit;strengthening the outer side of the foundation pit with isolation piles can effectively reduce the horizontal displacement of the diaphragm wall.The deformation of the isolation piles is the maximum in the soft and weak strata.Increasing the pile length can create a fulcrum constraint effect at the bottom of the pile,but cannot effectively reduce the displacement and axial force of the support structure;similarly,changing the stiffness of the isolation piles has a relatively small impact on the displacement and axial force of the support structure;only using the base reinforcement scheme can reduce the displacement of the support structure within the pit bottom range,but it has a small impact on the deformation of the upper support structure.The combination of isolation piles and base reinforcement scheme can effectively reduce the deformation and axial force of the support structure,reduce the adverse effects of eccentric loads on the foundation pit,and has a good reinforcement effect.

关 键 词：建筑物偏压超载 深基坑 软弱地层 隔离桩 基底加固 变形 

分 类 号：TU318.1[建筑科学—结构工程]