摘要
深基坑开挖时的空间效应明显,阳角部位变形大,受力复杂,是基坑安全和稳定性的重要风险点.青岛地铁苗岭路换乘车站深基坑位于上土下岩的组合地层中,开挖形状极不规则、周边高层建筑和管线情况复杂、存在多个阳角及基坑顶部超载等会使阳角部位积聚应力导致基坑局部失稳或破坏.因此,本文对该车站深基坑工程的阳角部位变形及稳定性开展相应研究.首先对阳角部位地表沉降、围护桩桩体侧移、桩顶水平位移等参数进行监测和分析,进而建立三维有限元模型,研究基坑阳角部位土体和围护结构的稳定性及相应加固措施效果.研究结果表明:无支护条件下,阳角部位出现应力集中与过大变形,发生楔形体滑动破坏;桩锚支护条件下,阳角部位地表沉降和围护结构变形等均处于设计限值之内,桩锚支护对上土下岩地层有限岩土体基坑阳角部位变形控制合理有效,两阳角公共边中部土体变形最大,土体滑裂面为椭球型;加强冠梁、腰梁连接及进行上覆土层注浆加固能有效保护阳角部位安全.
The obvious spatial effect of deep foundation pit excavation is featured by the large deformation and complicated stresses of the convex corner,and this is a critical risk point for the foundation pit to stay safe and stable.The deep foundation pit at the transfer station of Miaoling Road of Qingdao Metro is located in the combined stratum of upper soil and lower rock.The extremely irregular excavation shape,the arrangement of surrounding high-rise buildings and complicated pipelines,multiple convex corners,and the overload at the top of the foundation pit all contribute to the accu-mulated stresses on the convex corners,thus causing local instability or destruction of the pit.There fore,this paper conducts a study on the deformation and stability of the convex corner of the deep foundation pit.First,the parameters such as ground surface settlement,lateral displacement of the retaining piles and the pile tops are monitored and analyzed.Then a three-dimensional finite element model is established to study the stability and the reinforcement effect of the soil and the retaining structures around the convex corners.The research results indicate that in the condition of unsup-ported structures,stress concentration and larger deformation occurs at the convex corners,and the foundation pit develops wedge-shaped sliding failure.In the condition of supported structures,the ground surface settlement and the deformation of the retaining structures of the convex corners are all within the design constraints,and the pile-anchor support is effective in controlling the deformation of the convex corner in the foundation pit with upper soil and lower rock stratum.The largest soil deformation occurs at the shared edge of the two convex corners,and the sliding surface is shaped like an ellipsoid.Strengthening the connection of crown beam and waist beam and grouting reinforcement of the overlying soil layer can effectively protect the convex corner.
作者
商大勇
SHANG Dayong(China Railway Construction Investment Group Corporation Limited,Zhuhai Guangdong 519000,China)
出处
《北京交通大学学报》
CAS
CSCD
北大核心
2020年第6期25-33,43,共10页
JOURNAL OF BEIJING JIAOTONG UNIVERSITY
基金
国家重点研发计划(2018YFC0808701)。
关键词
地铁车站
土岩组合地层
深基坑
阳角
变形
subway station
soil-rock combined strata
deep foundation pit
convex corner
deformation
