基坑开挖坑底土拱效应离心模型试验及数值分析  

Centrifuge modeling of excavation and numerical analyses of soil arching below excavation base

作　　者：吴楷 陈仁朋[1,2,3] 孟凡衍 王瀚霖 程红战 WU Kai;CHEN Renpeng;MENG Fanyan;WANG Hanlin;CHENG Hongzhan(Research Center for Advanced Underground Space Technologies of Hunan University,Changsha 410082,China;College of Civil Engineering,Hunan University,Changsha 410082,China;Key Laboratory of Building Safety and Energy Efficiency of Ministry of Education,Hunan University,Changsha 410082,China)

机构地区：[1]湖南大学地下空间先进技术研究中心,湖南长沙410082 [2]湖南大学土木工程学院,湖南长沙410082 [3]湖南大学建筑安全与节能教育部重点实验室,湖南长沙410082

出　　处：《岩土工程学报》2024年第9期1936-1944,共9页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(52108318,52090082,51938005);湖南省自然科学基金面上项目(2021JJ30119);中央高校基本科研业务费资助项目。

摘　　要：基坑开挖会导致坑底产生土拱效应。与活动门上方土拱效应相比,基坑底土拱效应发展方向与土体自重应力方向相同且具有不同的力-位移边界条件。为探究土拱效应影响下基坑底土体竖向应力和回弹变形等力学响应,开展了干砂地层基坑开挖离心模型试验,并同时进行了不同开挖深度和宽度的多工况下数值分析。研究表明,基坑底地层存在差异变形和应力转移现象,证明了坑底土拱效应的存在;基坑底存在松动区和土拱区,松动区内土体相对密实度明显下降,土拱区以下地层回弹量仅占坑底总回弹量的20%;开挖深度和宽度是影响坑底土拱效应形成-演化的关键因素,二者与松动区和土拱区高度呈正相关。研究结论可为预测基坑开挖导致的地层响应和下方既有地下结构变形控制提供支撑。Soil arching may be generated below excavation base.This kind of soil arching is featured with different boundary conditions of mechanism and displacement compared with that above trapdoor,of which the development orientation is the same as that of soil gravity stress.To investigate the characteristics of the soil arching below excavation base,the centrifuge modeling of excavation with dry sand layer is conducted.Thereafter,a sequence of numerical analyses of the soil arching below excavation base are carried out under different excavation depths and widths.The research shows that the differential deformation and stress transfer are observed and the soil arching below excavation base is confirmed.The excavation base is divided into the loosened zone and the arching zone.The loosened zone exhibits a significant decrease in the relative density,while the arching zone accounts for about 80%basal heave.As the key to the formation and evolution of soil arching below excavation base,the depth and width of excavation are positively correlated with the range of the loosened zone and arching zone.The conclusions can provide a reference for the prediction of excavation-induced ground response and the deformation control of the underlying existing underground structures.

关 键 词：基坑开挖 土拱效应 离心模型试验 数值分析 

分 类 号：TU43[建筑科学—岩土工程]