近水平砂岩隧道初期支护变形破坏分析及控制技术

针对蒙华铁路段家坪近水平砂岩隧道高地应力条件下初期支护变形破坏的问题,应用地应力测试技术获得隧道围岩初始地应力分布规律,对初期支护变形破坏特征进行分析,提出了高应力水平地层支护设计对策,并应用于工程实践。研究结果表明:隧道区段处于以水平构造应力为主的高地应力状态且最大水平主应力方向不利于隧道的稳定;应力释放导致隧道原有初期支护开裂变形,混凝土破坏为压剪破坏,格栅钢架主筋破坏为受压失稳;采取增强支护参数、增设缓冲层、加装阻尼器等技术措施成功解决了高地应力水平岩层隧道初期支护变形破坏问题。

Analysis on Deformation and Destruction and Its Control Technology for Primary Support of Tunnel in Nearly Horizontal Sandstone Stratum

According to deformation and destruction of the primary support of the tunnel in nearly horizontal sandstone stratum in Duanjiaping area of Menghua Railway under the high geostress condition the initial geostress distribution of the tunnel surrounding rock was obtained by geostress test and the characteristics of deformation and destruction of primary support was analyzed at the same time.The corresponding support design scheme of tunnels in high geostress horizontal stratum was proposed and applied to engineering practice.The results show that the stress state of the tunnel section is a high geostress state dominated by horizontal tectonic stress and the direction of the maximum horizontal principal stress is not conducive to the tunnel stability.The stress release causes the existing primary support cracking and deformation.The failure of concrete is compression shear failure and the failure of the main rib of the grid steel frame is pressure instability.Adopting technical measures such as enhanced support parameters adding buffer layer and installing damper the deformation and destruction problem of the primary support of tunnel in high geostress horizontal stratum was successfully solved.