深基坑开挖诱发邻近运营地铁隧道变形响应特征研究

Research on deformation response characteristics of adjacent operation subway tunnels induced by deep excavation

为了研究深基坑开挖过程中基坑变形及对既有邻近运营地铁隧道变形的响应特征,本文结合深基坑案例现场监测数据,研究了深基坑开挖过程中支护结构、坑外地表以及地铁隧道变形的时程规律,探讨了支护结构变形与坑外地表变形、地铁隧道变形之间的相关性和响应特征,进一步揭示了深基坑卸荷作用下的地铁隧道变形特性机制。研究表明,支护结构变形与坑外地表变形、隧道变形速率具有明显的阶段性特征,三阶段的速率关系为:v_()Ⅱ>v_(Ⅲ)>v_(Ⅰ),与基坑施工工况具有较好的对应关系,并且坑外地表变形和隧道变形规律相对于支护结构变形有明显的滞后性;支护结构变形与周围土体、地铁隧道变形存在线性相关性,置信区间值为75%~90%,且沉降位移的相关性高于水平位移。研究结果可为类似深基坑安全、高效施工提供理论依据。

This work aims to investigate the deformation of a foundation pit during the excavation and its response of the adjacent operational subway tunnels.Combined with the on-site monitoring data of deep foundation pit cases,the time history of supporting structure,pit surface and subway tunnel deformation during the excavation was studied.The correlation and response characteristics between the deformation of the supporting structure,the deformation of the surface of the pit,and the deformation of the subway tunnel were discussed.Furthermore,the deformation mechanism of subway tunnel induced by the excavation unloading was revealed.The research indicate that the deformation of the support structure has obvious phased characteristics with the deformation rate of the surface outside the pit and tunnel.The rate relationship of the three stages is:v_()Ⅱ>v_(Ⅲ)>v_(Ⅰ),and have a good correspondence with the construction conditions of the foundation pit.Additionally,the deformation of the surface of the pit and the deformation of the tunnel have obvious hysteresis characteristics relative to the deformation of the supporting structure.The support structure deformation has a linear correlation with the surrounding soil and subway tunnel deformation.The confidence interval is 75%-90%.The correlation of settlement displacement is higher than that of horizontal displacement.These results may serve as a theoretical basis for ensuring the safe and efficient construction of similar deep foundation pits.