盾构隧道的近接施工对已建隧道产生的影响

为了研究天津市软土地区新建盾构隧道近接施工对已建隧道产生的影响,以天津地铁某区间最小净距为0.98 m的双线盾构隧道开挖工程为背景,采用有限元软件刚度迁移法,分析了在土体局部加固的情况下新建隧道掘进过程对已建隧道周围土体位移及衬砌内力与变形的影响,并将地表变形计算结果与实测数据进行了对比分析.结果表明:在注浆加固条件下,已建隧道的位移及内力都有较大程度的降低,但在加固区与未加固区交界附近可产生一定的突变,在现场施工时该段范围应重点监控.

Impact on Existing Tunnel Due to Construction of New Shield Tunnel in Close Proxomity

During the construction of small spacing shield tunnel in Tianjin soft ground,the magnitude of the advanced tunnel stresses and deformation changed. It was written according to the engineering project of Tianjin metro with the smallest interval of 0. 98 m. Stiffness migration method was employed to simulate the process of the new-construction tunnel,considering the soil reinforcement. The displacement of surrounding soil,internal force and displacement of the existing lining segment was analyzed and predicted. The calculated results were compared with the measured data,and the variation of the internal force and displacement was summarized. Results show that the grouting reinforcement largely reduced the displacement and internal force of the existing tunnel,but might produce certain mutations when just entering the reinforced region. It should be monitored during the tunnel construction.