基于隆起变形分析的基坑坑底抗隆起稳定可靠度分析  

Reliability Assessment of Basal⁃heave Stability Based on Deformation Analysis

作　　者：孟凯琪 刘志良 徐亮 李春立 李亮[1] 于忠福 高原 李辉 MENG Kaiqi;LIU Zhiiang;XU Liang;LI Chuni;LI Liang;YU Zhongfu;GAO Yuan;LI Hui(School of Civil Engineering,Qingdao University of Technology,Qingdao 266520,China;Qingdao Xinhuayou Construction Engineering Group Co.,Ltd.,Qingdao 266101,China;Qingjian Group Co.,Ltd.,Qingdao 266071,China)

机构地区：[1]青岛理工大学土木工程学院,山东青岛266520 [2]青岛新华友建工集团股份有限公司,山东青岛266101 [3]青建集团股份公司,山东青岛266071

出　　处：《防灾减灾工程学报》2024年第3期705-714,共10页Journal of Disaster Prevention and Mitigation Engineering

基　　金：国家自然科学基金项目(51778313)资助。

摘　　要：采用土体硬化(Hardening Soil)模型,在PLAXIS 2D中建立基坑开挖数值模型,在获取坑底特征点隆起变形数据的基础上构建坑底隆起变形超限失效模式对应的极限状态函数,为提高计算效率,应用响应面法代替有限元计算快速获取坑底特征点隆起变形值,结合蒙特卡罗模拟方法进行坑底抗隆起稳定性可靠度分析,分析结果表明:第三层土的卸载再加载模量E_(3)^(ur)以及有效内摩擦角φ’_(3)的变异性对坑底抗隆起稳定性影响显著;第一层土的有效黏聚力c’_(1)、有效内摩擦角φ’_(1)、割线模量E_(1)^(50)、切线模量E_(1)^(oed)以及第二层土的有效黏聚力c’_(2)的变异性对坑底抗隆起稳定性影响较小,但相对而言,第二层土的有效黏聚力c’_(2)对坑底抗隆起稳定性的影响较大;对于坑底土体为粉砂的深基坑来说,对坑内土体进行加固可以有效约束坑底隆起变形。A numerical model of excavation was established in PLAXIS 2D using the Hardening Soil model.Based on the heaving deformation data at characteristic points at the bottom of the excavation,a limit state function corresponding to the over-limit failure mode of heaving deformation was con-structed.To enhance the computational efficiency,the response surface method(RSM)was em-ployed,replacing finite element calculations to quickly derive heaving deformation values at the char-acteristic points.Combined with the Monte Carlo simulation method(MCS),the reliability of the anti-heaving stability at the bottom of the excavation was conducted.The results show that the variability in the unloading-reloading modulus(E ur 3)and effective internal friction angle(φ'_(3))of the third soil layer significantly impacted basal-heave stability.The variability in the effective cohesion(c'_(1)),effective in-ternal friction angle(φ'_(1)),secant modulus(E_(1)^(50))and tangential modulus(E_(1)^(oed))of the first soil layer and the effective cohesion of the second soil layer(c'_(2))had a smaller impact on basal-heave stability.How-ever,the effective cohesion of the second soil layer(c'_(2))exhibited a relatively large influence on basal-heave stability.For deep excavations with silty soils at the base,reinforcing the soil within the excava-tion effectively constrains base heaving deformation.

关 键 词：基底隆起稳定性 硬化土模型 响应面 蒙特卡罗法 

分 类 号：TU472[建筑科学—结构工程]