连拱变厚度曲中墙隧道围岩稳定性研究

Study on Stability of Double-arch Tunnel with Variational Curved Middle-wall

目前,国内外对连拱变厚度曲中墙隧道施工过程中围岩和支护的变形及破坏机理的研究成果很少。文章结合沪蓉西八字岭分岔隧道连拱段的工程地质条件和变厚度曲中墙结构设计特点,采用有限元程序模拟研究隧道动态开挖过程中围岩和支护结构的稳定性。研究成果表明:曲中墙上方围岩在开挖过程中应力变化较大,曲中墙厚度越大的断面,曲中墙上方围岩所受压应力越小,围岩发生塑性破坏的范围也越小,而曲中墙自身随着厚度的增大,所受的最大压应力也越小。最后,将该数值模拟成果与现场监测结果进行对比分析,其变化规律和现场实测结果基本一致。

There are few research achievements about deformation and damage mechanism for double - arch tunnel with thickness - changing curved middle - wall at home and aboard. Based on the geological feature and characteristic of support design of Baziling branch fork tunnel which belongs to Shanghai - Chengdu expressway, ABAQUS code is applied to simulate the whole process of double - arch tunnel to study the stability of rock mass and support. It can be concluded that the stresses of rock mass above the curved middle - wall have changed greatly during excavation. The thicker the curved middle - wall, the smaller the maximum compressive stress of surrounding rock, so does the plastic zone of surrounding rock mass. With thicker curved middle - wall, the compressive stress of curved intermediate -wall becomes smaller. Comparison between the numerical results and field measurements shows that, the variation of deformation and stress of rock mass and support obtained by simulation was in good agreement with that by field monitoing.