坑中坑基坑内坑支护桩弯矩发展规律  

Bending Moment Development Law of Supporting Pile in “Pit-in-Pit” Foundation Pit

作　　者：刘义 朱武卫 杨焜 席宇 LIU Yi;ZHU Wu-wei;YANG Kun;XI Yu(Research Institution of Underground Space Engineering,Shaanxi Architecture Science Research Institute Co.,Ltd.,Xian 710082,China)

机构地区：[1]陕西省建筑科学研究院有限公司地下空间工程研究所,西安710082

出　　处：《科学技术与工程》2023年第30期13085-13093,共9页Science Technology and Engineering

基　　金：陕西省科学技术厅重点研发计划(2021SF-459);陕西省科技统筹创新工程计划(2016KTZDSF04-4)。

摘　　要：坑中坑基坑是一种较为复杂且尚未得到充分研究的基坑形式。为研究基坑开挖过程中内坑支护桩的内力发展规律,进行了施工过程中的支护桩内力现场测试。通过采集桩身纵向受力钢筋的应力来反演桩身弯矩,分析了支护桩桩身弯矩在施工过程中的发展规律。通过有限元数值计算拟合了试验结果,研究了外坑开挖深度和平台宽度变化时内坑支护桩桩身弯矩的变化趋势,结果表明:坑趾系数(外坑平台宽度/开挖深度)与内坑支护桩桩身最大弯矩的变化存在着密切联系,通过拟合给出了桩身最大弯矩增长率随坑趾系数的函数曲线,桩身最大弯矩增长率可作为坑中坑基坑中内坑支护桩设计时的安全系数加以考虑。Pit-in-pit foundation pit is a complex and not yet fully studied foundation pit.In order to study the internal force development law of the inner pit support piles during the excavation of the foundation pit,the field test of the internal force of the support piles during the construction process was conducted.The bending moment of the supporting pile was calculated by collecting the stresses in the longitudinal reinforcement of the pile,and the development law of the bending moment of the supported pile during the construction process was analyzed.The experimental results were fitted by finite element numerical calculation,and the trend of the bending moment of the inner pit support pile was studied when the depth of the outer pit excavation and the width of the platform were varied.The results show that there is a close relationship between the pit toe coefficient(the ratio of platform widthto excavation depth of the outer pit) and the variation of the maximum bending moment of the inner pit support pile.The function curve of pile maximum moment growth rate of pit toe factor is given by fitting.The maximum moment growth rate of pile can be considered as the safety factor in the design of pit retaining pile in pit-in-pit foundation pit.

关 键 词：坑中坑 钢筋应力 支护桩弯矩 有限元数值计算 坑趾系数 

分 类 号：TU753[建筑科学—建筑技术科学]