富水圆砾地层超近间距顶管群施工地层扰动控制及分析

Disturbance Control and Analysis on Construction of Ultra⁃close⁃spaced Pipe Jacking Groups in Water⁃rich Gravel Formation

富水圆砾地层条件下顶管群组合式换乘通道施工目前在国内尚为罕见,其施工控制技术及对地层的扰动规律有待研究。围绕南宁地铁5号线明秀路站三管并行换乘通道工程,进行施工期地层扰动控制及分析研究,对顶管机、管片接口、洞门止水进行针对性设计,并配置与地层相匹配的减摩泥浆,同时开展施工过程中地表位移现场监测及数值模拟分析,得到以下结论:开挖初期的地层扰动影响较大,是地层控制的关键阶段,开挖面附近的地层小范围扰动剧烈,是控制的关键部位;横断面方向施工影响区域在并行三管总宽度2倍的范围;顶管掘进对地表直接扰动以上浮为主,当顶管上方有管线时,则容易产生沉降。

The construction of a combined transfer channel of pipe jacking group under the condition of a water⁃rich round gravel stratum is still rare in China,and its construction control technology and disturbance law to the stratum need to be studied.Based on the three⁃pipe parallel transfer channel project at Mingxiulu Station of Nanning Metro Line 5,the control and analysis of stratum disturbance during the construction period are implemented.The pipe jacking machine,segment interface and tunnel portal water stop were specifically designed,and the anti⁃friction slurry matching with the stratum was configured.Meanwhile,the field monitoring and numerical simulation analysis of surface displacement during construction were carried out.The following conclusions are obtained:the influence of stratum disturbance in the initial stage of excavation is great,which is the key stage of stratum control.The small⁃scale disturbance of stratum near the excavation face is severe,which is the key part of control.The construction influence area in the cross⁃section direction is in the range of twice the total width of the three parallel tubes.The pipe jacking excavation directly disturbs the surface and floats upward.Settlement is more likely to occur when there is a pipeline above the pipe jacking.