深基坑“墙-撑-锚”组合支护体系变形特性研究

Study on Deformation Characteristics of“Wall-Brace-Anchor”Composite Support System for Deep Foundation Pit

“墙-撑-锚”组合支护结构是深基坑工程中有效的支护形式。合理的支护设计可以提高基坑抗变形能力或降低施工成本。以北京霞光里5号、6号商业金融项目深基坑工程为例,在分析支护结构现场监测数据的基础上,采用数值模拟手段,拟合实测变形数据,进而提出“墙-撑-锚”组合支护体系下的基坑变形机制以及结构受力情况,并对其进行优化设计,为工程实践提供了科学建议。分析结果表明:“墙-撑-锚”支护结构的各部分协同作用,相互影响;一定范围内,增大墙体嵌固深度及墙体厚度,可减小墙体变形。支撑位置上移有利于控制墙顶水平位移,支撑位置下移至基坑中下部,可以提高围护结构的整体稳定性;适当增大锚固段长度、锚杆横截面积、施加的预应力大小、改变入射角度,都可以控制墙体变形。

“Wall-brace-anchor”composite support structure is an effective form of support in deep foundation pit engineering.Reasonable support design can improve the anti-deformation ability of foundation pit or reduce construction cost.Taking the deep foundation pit engineering of Beijing Xiaguangli No.5 and No.6 commercial and financial projects as an example,based on the analysis of the monitoring data of the supporting structure on site,this paper uses numerical simulation to fit the measured deformation data,and then puts forward the deformation mechanism and structural stress of the foundation pit under the“wall-brace-anchor”combined support system,and carries out the optimal design,which provides scientific suggestions for engineering practice.The results show that all parts of the wall-brace-anchor support structure interact with each other,and the wall deformation can be reduced by increasing the embedded depth and thickness of the wall within a certain range.Upward displacement of support position is beneficial to control horizontal displacement of the top of the wall,and downward displacement of support position to the middle and lower part of the foundation pit can improve the overall stability of the retaining structure.Appropriately increasing the length of anchorage section,cross-sectional area of anchor rod,applied prestressing force and changing the incident angle can control the deformation of the wall.