摘要
软土地层基坑开挖会对坑底土体产生严重扰动,受开挖扰动影响,坑底土体应力状态和力学性质将发生变化。因此,正确评价开挖扰动程度及扰动对土体工程性质的影响十分重要。通过对现有施工扰动评价方法的总结,以太湖隧道基坑工程为例,采用有限元模拟方法研究了不同开挖深度下坑底中心土体扰动度分布规律及强扰动区深度。进一步,以不排水抗剪强度为评价指标,建立了基于孔压静力触探(CPTU)锥尖阻力的黏性土开挖扰动评价方法,并与有限元扰动评价结果进行了对比,取得了较为一致的结果。最后,采用考虑土体扰动的沉降计算方法,结合有限元扰动度计算结果,对不同基底附加应力下坑底扰动土体的沉降变形进行了计算。计算结果表明,扰动会显著增加地基沉降量,当基底附加应力从100 kPa增加至150 kPa时,考虑土体扰动的地基沉降量与不考虑土体扰动的地基沉降量比值将从1.43增加至2.24。
The deep excavation of foundation pit in soft soil layer will cause serious disturbance to the soil at the bottom of the pit.Affected by excavation disturbance,the mechanical properties and stress state of the soil at the bottom of the pit will change.Hence,it is important to accurately evaluate the degree of soil disturbance caused by excavation and the influence of disturbance on soil mechanical properties.Based on the summary of the existing evaluation methods of soil disturbance,taking the foundation pit excavation of Taihu tunnel as an example,the distribution of disturbance degree and the depth of strong disturbed zone of soil under the center of the pit bottom under different excavation depths were studied by using the finite element simulation method.Then,taking the undrained shear strength as an evaluation index,a method for evaluating excavation disturbance of clayey soil based on the cone tip resistance in the piezocone penetration test(CPTU)was established.The soil disturbance calculated through cone tip resistance was agreeable with that determined by numerical calculation.Finally,combined with the soil disturbance determined by the finite element method,the settlement of disturbed soil at the bottom of the pit under different base additional stresses was calculated considering the settlement of soil disturbance.The results showed that the soil disturbance would cause a significant increase in the base settlement.When the base additional stress increased from 100 kPa to 150 kPa,the ratio of base settlement with soil disturbance to that without soil disturbance would increase from 1.43 to 2.24.
作者
鲁泰山
刘松玉
蔡国军
吴恺
夏文俊
LU Tai-shan;LIU Song-yu;CAI Guo-jun;WU Kai;XIA Wen-jun(Institute of Geotechnical Engineering,Southeast University,Nanjing,Jiangsu 211189,China;Jiangsu Key Laboratory of Urban Underground Engineering and Environmental Safety,Southeast University,Nanjing,Jiangsu 211189,China;Jiangsu Provincial Transportation Engineering and Construction Bureau,Nanjing,Jiangsu 210004,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2021年第2期565-573,580,共10页
Rock and Soil Mechanics
基金
国家自然科学基金(No.41972269)
江苏省交通工程建设局科技项目(No.CX-2019GC02)
关键词
软土
基坑开挖
扰动
孔压静力触探
沉降
soft soil
excavation
disturbance
piezocone penetration test
settlement
作者简介
第一作者:鲁泰山,男,1996年生,博士研究生,主要从事原位测试方面的研究。E-mail:230189653@seu.edu.cn;通讯作者:刘松玉,男,1963年生,博士,教授,博士生导师,主要从事地基处理及原位测试等方面的研究。E-mail:liusy@seu.edu.cn
