粉质黏土中大直径泥水盾构隧道管片上浮及错台现场测试分析

In situ test analysis of segment uplift and dislocation of large-diameter slurry shield tunnel in silty clay

与一般城市地铁隧道相比,大直径盾构隧道管片面临的上浮问题愈加突出。为研究大直径盾构隧道施工期管片上浮及错台发展规律及其影响因素,依托济南黄河隧道工程,对管片上浮、错台及收敛变形进行监测研究。基于监测结果及施工参数,分析管片上浮和错台发展规律,横、纵向上浮分布特征及管片收敛变形规律,并对上浮与错台、施工参数进行相关性分析。在此基础上,指出管片上浮及错台的关键控制区域并提出控制措施。研究结果表明:大直径泥水盾构在以粉质黏土为主的地层中掘进时,管片上浮过程可分为初始变形(拱底上浮占比35%)、快速上浮(拱底上浮占比40%)、平缓上浮(拱底上浮占比30%)和缓慢沉降(拱底沉降占比5%)4个阶段。管片从拱顶到拱底上浮量线性递增,上浮量占比及竖向收敛变形在纵向上呈指数型发展,且上浮受掘进速度、上部盾尾间隙影响较大。管片距盾尾0.5D内收敛变形速率较大,距盾尾1.6D时收敛变形趋于稳定。管片错台与上浮线性相关,且错台发展过程可分为:快速减小(环缝距盾尾-2~1 m)、增长(环缝距盾尾1~14 m)和稳定3个阶段。盾尾后方1~4环为管片上浮和错台的最佳控制区域。研究成果对于大直径盾构隧道上浮和错台导致的隧道管片受力研究及现场保护具有参考价值。

In comparison with the general urban subway tunnels,the problem of upward moving of largediameter shield tunnel segments has become more prominent.In order to study the development and its influencing factors of uplift and dislocation of large-diameter shield tunnel segments during tunnelling,the uplift,dislocation and convergence of segments were studied from in-situ tests of the Jinan Yellow River Tunnel project.Based on the monitoring results and construction parameters,the development of segment uplift,dislocation and convergence was studied,as well as uplift distribution of single segment and continuous segments,and the correlations between segment uplift and dislocation,construction parameters were analyzed.The key control areas of segment uplift and dislocation during tunnelling were pointed out,and the corresponding control measures were put forward.The results show that for the large-diameter slurry shield passing through the stratum dominated by silty clay,the uplift process of segments can be divided into four stages:initial deformation stage(arch bottom uplift accounts for 35%),rapid floating stage(arch bottom uplift accounts for 40%),gentle floating stage(arch bottom uplift accounts for 30%),and slow settlement stage(arch bottom settlement accounts for 5%).The uplift increases linearly from the top to the bottom of the segments;however,in the longitudinal direction,with the increase of the distance from the shield tail,the ratio of segment uplift to final amount and vertical convergence changed exponentially,the segment uplift was greatly affected by the excavation speed and the upper clearance of shield tail.When the segment is less than 0.5D away from the shield tail,the convergence deformation rate of segment is large,and it tends to be stable when the distance increases to 1.6D.The segment dislocation is linearly related to the uplift,and it can be divided into the following stages:rapid reduction stage(circumferential joint distance from shield tail-2~1 m),growth stage(circumferential joint distance from shield tail 1~14 m) and stable stage.The best control area for the uplift and dislocation of the segment is 1~4 rings behind the shield tail.The research results have important value for the study of the forces of the large-diameter tunnel segment caused by the uplift and dislocation of the segment and the on-site protection.