基于侧向位移特性的长大基坑空间效应分析

Analysis on Spatial Effect of Long and Large Foundation Pit Based on Lateral Displacement Characteristics

以砂土地区的长大基坑工程为研究对象,结合现场实测数据,分析基坑开挖导致的围护结构侧向位移和土体侧向位移的变形特征。基于侧向位移变形指标的整体发展规律,提出考虑空间效应的长大基坑整体变形模式。研究结果表明,分区分段开挖的长大基坑变形规律有别于整体开挖基坑的变形规律,坑角位移明显小于基坑中部位移,开挖最早完工的中部对边侧的基坑变形具有限制作用;墙体侧向位移与土体侧向位移沿基坑长边表现的空间分布变形趋势具有一致性,从而可以依据墙体侧向位移预测土体侧向位移。通过分析变形的激增区和累积最大变形的发生区域等,可以确定基坑危险工况,提出加强基坑的措施。研究结论对于优化基坑工程设计、保障施工安全有非常重要意义。

Taking a long and large foundation pit project in sandy soil area as the research object,and combined with the measured data of the site,the characteristics of the lateral displacements of retaining structures and soil body caused by the excavation of foundation pit are analyzed.Based on the integral development law of lateral displacement and deformation indexes,an integral deformation mode of long and large foundation pit considering the spatial effect is proposed.The research results show that the deformation law of long and large foundation pit by the segmental excavation is different from the integral excavated foundation pit.The displacement at pit corner is significantly smaller than the displacement at the central part.The central part of the earliest finished excavation has the restriction to the deformation of the foundation pit on both sides.The spatial distribution deformation trend of wall lateral displacement and soil lateral displacement along the long side of foundation pit is consistent.Thus,the soil lateral displacement can be predicted according to the wall lateral displacement.By analyzing the sharp increase of deformation and accumulating the maximum deformation area,the dangerous construction period of foundation pit can be determined and the measures to strengthen the pit are proposed.The research conclusion is meaningful to optimize the engineering design of foundation pit and guarantee the construction safety.