基坑降水开挖对地铁高架桥墩的影响分析

Influence of foundation pit dewatering and excavation on subway viaduct piers

依托苏南下穿地铁高架线某新建地铁车站基坑项目,进行基坑开挖对邻近运营地铁高架的影响研究。采用三维数值模拟方法结合现场监测分析对近距离基坑开挖引起的高架桥墩响应进行研究,结果表明:基坑降水开挖过程中,土体开挖较浅时,受卸荷效应影响桥墩基础会有所上抬,随基坑降水以及开挖深度加深,桥墩基础发生沉降;桥墩基础水平位移朝向基坑开挖一侧,位移发展较缓慢且位移值较小;桩体在开挖过程中产生水平方向上的变形,且主要集中在围护结构固嵌深度范围以内;基坑开挖会造成邻近的桩基极限承载力轻微损失,但能满足最大设计荷载要求。

Based on the foundation pit project of a newly built subway station which underpasses metro viaduct in the south of Jiangsu,the influence of foundation pit excavation on the adjacent operating subway viaduct is studied.By using the three-dimensional numerical simulation method combined with field monitoring data the paper also studies the response of viaduct piers caused by short-distance excavation.The results show that during the process of foundation pit dewatering excavation,the pier foundation will be lifted due to the unloading effect when the soil excavation is shallow.With the dewatering of foundation pit and the deepening of excavation depth,the pier foundation will be subsided.The horizontal displacement of piers develops toward the excavation side,the displacement develops slowly and the displacement value is small.During the excavation process,the horizontal deformation of pile is mainly concentrated within the embedded depth of retaining structure.Excavation of foundation pit will cause slight loss of ultimate bearing capacity of adjacent pile foundation,but it can meet the requirement of maximum design load.