摘要
依托富水砂土深基坑工程2次墙体严重渗水事故,通过现场调查和实测数据回顾,分析渗水期间基坑变形特性并总结事故原因.建立三维流固耦合数值模型揭示渗水灾变机理,对墙体渗水多种复杂工况展开研究.结果表明,富水砂土基坑渗水事故具有突发性,墙体1.075倍最终开挖深度处发生渗水可使墙后总水力梯度和水土压力分别突增至事故前的9.0~12.0倍和3.0~3.6倍,导致地连墙侧向位移快速增长.相较于开挖面以下渗水工况,开挖面及以上墙体渗水引起的坑外地表沉降增量更大,最大增量处距坑边更近,且影响范围更大.除了明显的承载和阻隔变形作用,隔离桩还能有效削弱渗水时动水力的作用,但当桩长超过最优临界值(1.6倍最终开挖深度)时,隔离桩保护效果的改善将不再明显.
Based on two severe through-wall leaking accidents during deep excavations in water-rich sandy strata,the deformation behaviors of the excavation during leaking were investigated and the major causes incurring the accidents were summarized by field investigation and review of measured data.To reveal the disaster-causing mechanism of leakages,a 3D fluid-solid coupled numerical model was established and several leaking scenarios were analyzed.The results indicate that the leaking accidents occur suddenly during excavation in water-rich sandy strata.When the leakage takes place at 1.075 times the final excavation depth,the total hydraulic gradient and water-earth pressure behind the wall undergo a sudden increment up to 9-12 times and 3-3.6 times those before the incident,respectively,causing a rapid increase in lateral wall displacements.Compared with the case leaking below the excavation surface,a greater increment of ground settlement,a closer distance between the location at which the maximum increment happens and the excavation pit,and a larger affected region will be incurred for the cases where the through-wall leakages are exactly at or above the excavation surface.In addition to the obvious effects of load-bearing and isolating deformation,the dynamic seepage forces during leaking can also be weakened by the isolation piles.However,when the pile length exceeds the optimal value(1.6 times the final excavation depth),the improvement on protective effects of the isolation piles is no longer obvious.
作者
刘俊城
谭勇
宋享桦
樊冬冬
刘天任
LIU Jun-cheng;TAN Yong;SONG Xiang-hua;FAN Dong-dong;LIU Tian-ren(Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China;Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University,Shanghai 200092,China)
出处
《浙江大学学报（工学版）》
EI
CAS
CSCD
北大核心
2023年第3期530-541,共12页
Journal of Zhejiang University：Engineering Science
基金
国家自然科学基金资助项目(42177179).
关键词
富水砂层
深基坑
渗水
隔离桩
数值模拟
water-rich sandy strata
deep excavation
leaking
isolation pile
numerical simulation
