上方基坑施工既有隧道变形演化特征分析

Deformation Evolution Characteristics Analysis of The Existing Tunnel During the Deep Excavation Above

随着城市地下空间利用率越来越高,既有隧道上方基坑的变形特征对于施工安全和支护设计具有重要的指导意义。依托杭州天目山路改造项目,基于基坑与下方既有隧道的监测数据,分析了基坑施工过程中本基坑及旁侧基坑的地表沉降等特征规律,并监测获得了下方既有隧道在基坑施工过程中道床沉降变形的一般规律。结果表明,合理的围护结构可以有效控制基坑周边沉降变形,在上方基坑加固阶段,下方既有隧道受影响最大,产生了较大的沉降变形,而加固后的施工阶段变形反而较小。研究结果对于施工设计与风险控制具有参考意义。

With the increasing utilization of the underground space in urban areas,studying the deformation characteristics of the deep excavation above the existing tunnels is of significant importance for the construction safety and the support design.Based on the Tianmu Mountain Road transformation project,the surface settlement of both the excavated area and adjacent excavations were analyzed during the excavation process,and the general rules of settlement deformation of the underlying existing tunnel were monitored and obtained.The results showed that a reasonable supporting structure can effectively control the settlement deformation around the foundation pit,and during the reinforcement stage above the foundation pit,the existing tunnel below was significantly affected,resulting in significant settlement deformation.However,the deformation during the construction stage after reinforced was relatively small.The finding of this study has reference value for construction design and risk control.