摘要
南京某超深基坑工程采用异形围护结构双层地下连续墙进行施工,双墙间土体处于非极限平衡状态,土压力分布演变形式及墙土间相互作用机制并不明确。为探明深基坑开挖施工引起的双墙间有限土体的土压力变化规律及墙外侧土拱效应对土压力分布的影响,采用现场实测分析结合物理模型计算的方法开展研究。首先,通过现场试验在土层中布设土压力监测点,获取基坑开挖过程中墙间土压力演变规律;其后,建立考虑土体分层的曲面锥形土拱模型,计算侧土拱发展引起的墙外土压力变化量,并结合试验数据的参数反演和误差分析对模型计算结果的准确性展开讨论。研究结果表明:基坑开挖施工对双墙间土体的影响总体呈现为挤压变形,有限土体受到的侧向约束作用有助于进一步发挥土体的抗剪强度;基坑开挖各工序中土方开挖过程对地层扰动最为显著;侧土拱效应进一步增大了浅层土体挡土墙侧土压力,而中深层土体中几乎没有侧土拱发展;考虑侧土拱效应的土压力计算结果较传统水土分算的Coulomb理论计算方法与现场实测结果更加吻合。本研究可为异型围护结构的深基坑工程设计及施工提供思路与建议。
A super-deep foundation pit project in Nanjing is constructed with a double diaphragm wall of shaped enclosure structure.The soil between the double walls is in a non-limit equilibrium state,and the evolution of soil pressure distribution and the mechanism of wall-soil interaction are not well understood.To investigate the soil pressure variation within the limited soil body between the double walls caused by deep foundation pit excavation,and to examine the influence of the soil arching effect on the soil pressure distribution outside the walls,this study employs a combination of on-site measurement analysis and physical model calculations.Initially,earth pressure monitoring points are established within the soil layers through field testing,aiming to capture the evolution of earth pressure between the walls during the excavation process.Subsequently,a curved conical soil arch model is established,taking into account the layering of the soil body.This model calculates the changes in earth pressure outside the walls due to the development of lateral soil arches.The accuracy of the model’s results is then discussed through parameter inversion and error analysis of the experimental data.The findings reveal that the excavation process predominantly impacts the soil between the double walls by causing compressive deformation.The lateral constraints imposed on this limited soil body contribute to further enhancing its shear strength.Among various excavation stages,the soil excavation process significantly disturbs the geological layers.The lateral soil arching effect further increases the earth pressure on the shallow soil retaining wall,while there is almost no development of lateral soil arches in the middle and deep soil layers.When considering the lateral soil arching effect,the calculated soil pressure aligns more closely with field measurements compared to the traditional Coulomb theory method,which separately calculates soil and water pressures.This study can provide insights and suggestions for the design and construction of deep foundation pit projects with special-shaped enclosure structures.
作者
陕耀
董雅丞
张旭辉
姚西平
SHAN Yao;DONG Ya-cheng;ZHANG Xu-hui;YAO Xi-ping(Key Laboratory of Road and Traffic Engineering of the Ministry of Education,Tongji University,Shanghai 201804,China;Shanghai Key Laboratory of Rail Infrastructure Durability and System Safety,Shanghai 201804,China;Nanjing Metro Construction Co.,Ltd.,Nanjing,Jiangsu 210017,China;Jiangsu Railway Group Co.,Ltd.,Nanjing,Jiangsu 300308,China;Jiangsu Province Engineering Research Center of Intelligent and Green Railway,Nanjing,Jiangsu 210012,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2024年第S01期507-516,共10页
Rock and Soil Mechanics
基金
国家自然科学基金青年科学基金资助项目(No.51708424)
关键词
地下连续墙
土压力
现场实测
侧土拱效应
对比分析
diaphragm wall
earth pressure
field measurements
lateral soil arch effect
comparative analysis
