邻近密集管线深基坑开挖地层变形分析

Analysis of Ground Deformation Caused by Excavation of Deep Foundation Excavation Under Adjacent Dense Pipelines

为了研究邻近密集管线下地铁车站基坑开挖引起的地层变形,以北京地铁某换乘站基坑为工程背景,对地表沉降和管线沉降进行现场监测分析。运用MIDAS/GTS软件建立有限元模型,在与实测值进行对比验证模型准确性的基础上,进一步分析地下连续墙水平位移和既有管线的变形规律。研究结果表明:最大管线沉降位置与基坑长边邻近管线侧的最大地表沉降位置对应,所有管线的沉降值均小于监控量测控制要求;邻近管线的竖向位移较水平位移更大,管线的断面尺寸越大,距离基坑越近,其产生的管线沉降越大;管线的位移分布存在明显的空间效应,呈现出在基坑中心处位移大而两端位移小的特点。

To study the ground deformation caused by the excavation of the subway station foundation excavation under adjacent dense pipelines,the surface settlement and pipeline settlement are monitored and analyzed on the spot with the foundation excavation of a transfer station in Beijing Metro as the engineering background.The finite element model is established by using Midas/GTS software.Based on the comparison with the measured values to verify the accuracy of the model,the deformation horizontal displacement of the underground continuous wall and the deformation law of the existing pipeline are further analyzed.The results show that the maximum pipeline settlement position corresponds to the maximum surface settlement position of the pipeline side adjacent to the long side of the foundation excavation,and the settlement values of all pipelines are less than the monitoring and measurement control requirements.The vertical displacement of the adjacent pipeline is greater than the horizontal displacement.The larger the cross-sectional size of the pipeline and the closer the distance from the foundation excavation,the greater the settlement of the pipeline generated.And there is an obvious spatial effect on the displacement distribution of the pipeline,showing the characteristics of large displacement at the center of the foundation excavation and small displacement at both ends.