东干渠工程施工期间来广营地区地面沉降研究

Study on land subsidence in Laiguangying Area during construction of East Main Canal Project

作为北京市南水北调配套工程的重要组成部分,东干渠工程穿越了城区北部来广营和东部王四营两个区域地面沉降中心区域。通过收集和整理东干渠工程施工期间来广营地区地面沉降监测资料,研究东干渠隧洞施工期间该地区地面沉降的时空响应规律,进而对地下隧洞工程的地面沉降监测范围、监测时机、控制指标等进行分析。结果表明:在隧洞施工期间,来广营地区地面沉降的空间响应范围在顺洞轴线方向为监测断面后方-50 m至前方+1 400 m,垂直洞轴线方向的最大影响范围为1.0倍隧洞埋深范围。地面沉降的最大沉降速率和累积沉降量均小于该工程设计控制指标。隧洞一、二衬施作期间洞顶地面变形表现为隆起与沉降交替变化的过程。研究成果不仅为同类工程积累了经验,也为北京平原区地面沉降易发区域隧洞工程施工期间沉降控制标准的适宜性提供了例证。

As an important part of the ancillary works for the South to North Water Transfer Project in Beijing,the East Main Canal crosses the land subsidence central areas in Laiguangying Area in the northern part of the urban area and Wangsiying Area in the east part of the urban area. Through collecting and sorting the data of land subsidence monitored in Laiguangying Area during the construction of the East Main Canal Project,the law of the temporal and spatial response of the land subsidence in the area during the construction of the tunnel for the canal is studied,and thenthe range,timing,control index of the monitoring on the land subsidence for the construction of the tunnel are analyzed as well. The result shows that during the tunnel construction,the spatial response of land subsidence in Laiguangying Area ranges from-50 m behind the monitoring cross-section to ＋ 1 400 m in front of that in the direction of the tunnel axis. The maximum influence range in the direction perpendicular to the axis of the tunnel is 1. 0 times the buried depth of the tunnel. Both the maximum settlement rate and cumulative settlement of land subsidence are less than the design control indexes of the project. The deformation of the ground surface over the tunnel roof exhibits an alternated changing process of both heave and settlement during the construction periods of the primary and secondary linings of the tunnel. The study result not only accumulates the relevant experiences for the similar projects,but also provides an actual case for the suitability of the relevant settlement control standard for the construction of the tunnel in the area prone to land subsidence within Beijing Plain Area.