考虑基坑宽度及软弱土层厚度的基坑抗隆起稳定可靠度研究  

Study on the basal-heave stability and reliability of foundation pitconsidering excavation width and thickness of soft soil layer

作　　者：孟凯琪 王铭浩 焦力 李亮[1] 徐亮 胡俊[3] 高原 MENG Kaiqi;WANG Minghao;JIAO Li;LI Liang;XU Liang;HU Jun;GAO Yuan(School of Civil Engineering,Qingdao University of Technology,Qingdao 266525,China;Qingdao Real Estate Development Center,Qingdao 266071,China;School of Civil and Architectural Engineering,Hainan University,Haikou 570228,China;Qingdao Xinhuayou Construction Engineering Group Co.Ltd.,Qingdao 266101,China)

机构地区：[1]青岛理工大学土木工程学院,青岛266525 [2]青岛市房地产事业发展中心,青岛266071 [3]海南大学土木建筑工程学院,海口570228 [4]青岛新华友建工集团股份有限公司,青岛266101

出　　处：《青岛理工大学学报》2024年第4期35-44,共10页Journal of Qingdao University of Technology

基　　金：国家自然科学基金地区科学基金项目(51968019)。

摘　　要：坑底隆起破坏是导致基坑失稳的关键因素之一。对坑底隆起的影响因素展开研究工作,分析基坑宽度以及软弱土层厚度对坑底隆起变形以及基坑抗隆起稳定可靠度的影响规律。首先,建立不同工况的基坑开挖有限元模型,获取坑底不同特征点的隆起变形值,分析其变形规律,进而构建基于隆起变形限值的坑底抗隆起失效极限状态函数,最后采用蒙特卡罗法对坑底进行概率分析。数值模拟结果表明:当软弱土层厚度足以使隆起破坏滑动面贯通时,窄基坑的坑底两侧隆起变形大,中间小,宽基坑隆起变形规律与之相反;两种类型基坑坑底隆起变形都随基坑宽度增加而增大。改变软弱土层厚度,坑底各特征点隆起变形值随之变化,当为窄基坑时,坑底隆起变形依旧是中间小,两侧大;当基坑为宽基坑时,随软弱土层厚度增加,隆起变形随之增大,且坑底中心隆起变形逐渐超过两侧隆起变形;依据变形规律得到不同宽度基坑隆起破坏滑动面贯通时的软弱土层厚度。坑底抗隆起稳定可靠度与基坑宽度、特征点位置以及软弱土层厚度有关,坑底的稳定状态以及可靠度最低的特征点位置随基坑宽度以及软弱土层厚度变化而变化。Basal-heave is one of the key factors affecting the stability of foundation pit.This study aims to investigate the influence of excavation width and the thickness of soft soil layer on the basal-heave deformation and basal-heave stability and reliability.Firstly,finite element models are established for different working conditions to obtain the substrate deformation data of the characteristic points at the bottom of the foundation pit and analyze their deformation laws.Secondly,the limit state functions are established in terms of acceptable basal-heave deformation.Finally,the Monte Carlo method is used to perform probabilistic analysis of the pit bottom.Numerical simulation results show that for narrow pits,when the thickness of the soft soil layer is sufficiently enough to guarantee the complete generation of failure zones,there are large deformations on the two sides of the foundation pits and small deformations in the middle.Conversely,for wide pits,there are large deformations in the middle of the foundation pits and small deformations on the two sides.For both types of pits,the deformation of basal-heave increases with the increase of pit width.Changing the thickness of the soft soil layer,the deformation of each characteristic point changes accordingly,and the basal-heave deformation remains small in the middle and large on both sides for narrow pits.With the increase of the thickness of the soft soil layer,the value of basal-heave deformation at each characteristic point of the pit bottom increases,and the basal-heave deformation at the center of the pit bottom gradually exceeds deformation at both sides for wide pits.According to the deformation law,we can obtain the thickness of the soft soil layer when the thickness is sufficiently enough to guarantee the complete generation of failure zones.The stability and reliability of basal-heave is hinged on the width of pits,the location of each characteristic point and the thickness of the soft soil layer.The stability of the pit bottom and the location of th

关 键 词：基坑工程 基坑抗隆起稳定可靠度 响应面法 坑底隆起变形值 可靠度 

分 类 号：TU471[建筑科学—结构工程]