软土地区某地铁车站深基坑变形分析

Deformation Analysis of Deep Foundation Pit of a Subway Station in Soft Soil Area

软土地区深基坑的开挖大变形问题,对基坑安全存在较大的威胁,因此对软土基坑开挖变形分析,探究软土基坑开挖变形规律,对降低软土深基坑施工风险反馈优化基坑设计具有现实意义。以宁波地区某地铁软土深基坑工程实例为研究背景,整理基坑开挖施工期间周边14个地表沉降监测断面及14个围护结构测斜监测点数据,深入分析了基坑围护结构变形规律与地表沉降变形规律,得出:基坑围护结构变形最大值(δ)处于0.35%H~1.44%H之间,地表沉降与基坑开挖深度之间关系为:最大δ=1.27%H,最小δ=0.28%H,平均值δ=0.78%H,两者均远大于变形控制标准值。该成果可为类似软土基坑监控变形分析、软土深基坑设计提供借鉴。

The large deformation of deep foundation pit excavation in soft soil area is a great threat to the safety of foundation pit.Therefore,it is of practical significance to analyze the deformation of soft foundation pit excavation and explore the deformation law of soft foundation pit excavation,so as to reduce the risk of deep foundation pit construction and optimize the design of foundation pit by feedback.Based on the case study of a deep foundation pit of Metro soft soil in Ningbo area,this paper collates the data of 14 surface settlement monitoring sections and 14 inclinometer monitoring points around the foundation pit during the excavation construction,analyzes the deformation law of the foundation pit retaining structure and the surface settlement deformation law,and concludes that the maximum deformation value(δ) of the foundation pit retaining structure is between 0.35%H~1.44%H,and the surface settlement is between 0.35%H and 1.44%H,the relationship between the excavation depth of foundation pit is that the maximum δ=1.27%H,the minimum δ=0.28%H,and the average δ=0.78%H,both of which are far greater than the standard value of deformation control.The results can be used as reference for the deformation analysis of similar soft soil foundation pit monitoring and the design of deep soft soil foundation pit.