基坑开挖引起周围管线位移分析

Analysis on the Displacement of Surrounding Pipeline Caused by Deep Foundation Pit Excavation

摘要:

为探讨深基坑开挖对周围管线位移的影响，明确管线位移轨迹模式，以南京江东软件城深基坑工程为背景，对管线位移实际监测数据进行分析。首先介绍该基坑工程的设计、施工和监测方案；在此基础上结合施工过程，分析周围4根管线竖向沉降和水平位移发展规律，并探讨二者之间的关系，揭示管线位移轨迹。由分析可知，竖向沉降先于水平位移发生，随基坑施工的开展，竖向和水平位移同步增大；在基坑第二道支撑施工后，竖向沉降出现平台，水平位移明显减小；地下室底板施工后，变形趋于稳定。距离基坑侧壁垂直距离较近的管线位移轨迹为三次多项式曲线，距离基坑侧壁较远的管线沿直线状向坑脚移动。

关键词:基坑开挖;基坑监测;管线;位移轨迹;顺作法

Abstract:

To further understand the effect of deep foundation pit excavation on surrounding pipelines and determine the pipeline displacement track model, with the background of a deep foundation pit project of Nanjing, the analysis is made on the actual monitoring data of pipeline displacement. The design, construction and monitoring schemes of the foundation pit project are introduced; on this basis, according to the construction process, this paper analyzes the variation rules of vertical settlement and horizontal displacement of 4 surrounding pipelines and explores the relationship between them to reveal pipeline displacement track. By the analysis, it is concluded that the vertical settlement happened prior to the horizontal displacement in time domain, along with the development of foundation pit construction, vertical settlement and horizontal displacement developed synchronously; after the completion of the second support construction for foundation pit, the vertical settlement exhibits plateaus and the horizontal displacement reduced; after the construction of the basement floor, both the horizontal settlement and vertical displacement tend to be stable. The track of the pipeline displacement track vertically closer to the foundation pit side wall is a cubic polynomial curve and the pipeline displacement track far from the foundation pit side wall moves straightly toward the foot of the pit.

Key words:foundation pit excavation; foundation pit monitoring; pipeline; displacement track; normal excavation construction method