摘要
软土区柔性支护管廊基坑工程变形控制难度大、造价高,变形控制标准亟待优化。针对广州南沙柔性支护的典型管廊基坑开展了有限元分析,总结了基坑变形规律。基坑开挖到底时,围护结构桩身变形由“悬臂式”变为“内凸形”,坑外地表沉降影响范围达到4~5倍基坑开挖深度,明显大于其他刚度较大的支护结构,坑底隆起变形呈“中间大两边小”的形态。在此基础上,研究了6个不同基坑断面在临界失稳状态与稳定性满足规范两种条件下,围护结构变形最大值与基坑开挖深度的比值,建议将计算结果的平均值作为控制值的参考值。基坑临界失稳状态下,设计安全等级为二级和三级的基坑围护结构水平变形控制参考值分别为2.62%H、3.24%H(H为基坑深度)。基坑稳定性满足规范要求时,设计安全等级为二级和三级的基坑围护结构水平变形控制参考值分别为0.8%H、0.93%H。
It is difficult and costly to control the deformation of the pipe gallery excavation with flexible support in soft soil area.The deformation control standards need to be optimized urgently.The finite element analysis was carried out for the typical pipe gallery excavation with flexible support in Guangzhou Nansha.The deformation law of excavation was summarized.When excavating to the bottom,the deformation of the retaining structure changes from“cantilever type”to“inner convex type”.The influence range of surface settlement outside the excavation is 4~5 times the excavation depth,which is obviously larger than other retaining structures with larger stiffness.The basal heave deformation is“large in the middle and small on both sides”.On this basis,the ratio of the maximum value of the retaining structure horizontal deformation to the excavation depth was studied under the two conditions of critical instability state and stability meeting the specification for 6 different excavation sections.The average value of the calculated results was recommended as the reference value for the control value.Under the critical instability state,the reference values for the horizontal deformation control of the retaining structure with the design safety level two and three are 2.62%H and 3.24%H respectively,H is the depth of the foundation pit.When the stability of the excavation meets the requirements of the specification,the reference values for the horizontal deformation control of the retaining structure with the design safety level two and three are 0.8%H and 0.93%H respectively.
作者
李天降
朱孟君
王哲
宋许根
甄洁
衣凡
雷华阳
郑刚
程雪松
LI Tian-jiang;ZHU Meng-jun;WANG Zhe;SONG Xu-gen;ZHEN Jie;YI Fan;LEI Hua-yang;ZHENG Gang;CHENG Xue-song(Road Traffic Design and Research Institute,China Railway Siyuan Survey and Design Group Co.,Ltd.,Wuhan 430063,China;Department of Civil Engineering,Tianjin University,Tianjin 300072,China)
出处
《科学技术与工程》
北大核心
2023年第21期9199-9206,共8页
Science Technology and Engineering
基金
中铁第四勘察设计院集团有限公司重点科研课题(2020k118)
住房和城乡建设部支撑产业转型升级重点研发项目(2020k155)
国家自然科学基金(52178343)。
关键词
软土区
管廊基坑
柔性支护结构
变形控制标准
有限元模拟
soft soil area
pipe gallery excavation
flexible retaining structure
deformation control standard
finite element model
