兰渝铁路高地应力软岩隧道挤压大变形规律及分级标准研究

On the Large Squeezing Deformation Law and Classification Criteria for the Lanzhou-Chongqing Railway Tunnels in Soft and High Geostress Rocks

软岩隧道在高地应力作用下产生挤压大变形是必然现象。为有效控制挤压大变形,文章结合兰渝铁路软岩隧道工程特性,基于均质地层圆形洞室弹塑性位移解析解和我国现行规范围岩参数,研究了软岩隧道挤压大变形的规律,并提出了大变形分级标准及相应防治措施。在Hoek提出的无支护条件下围岩挤压程度分级标准基础上,以兰渝铁路软岩隧道为工程背景,考虑支护抗力作用,提出了在设计阶段以相对变形和岩体强度应力比为分级指标,将挤压大变形分为三个等级,根据岩体强度应力比进行大变形预测;在施工阶段以变形量和变形速率为分级指标,提出了三级验证标准和变形管理基准以及设计和施工阶段相应防治措施。通过实践验证,隧道大变形得以控制。

It is commonly believed that it is inevitable for a tunnel in soft rock to incur large deformation due to squeezing under high geostress. To control tunnel deformation in squeezing rock, this paper studies the deformation law, classification criteria, and corresponding countermeasures in light of the engineering characteristics of the squeezing-rock tunnels on the Lanzhou-Chongqing railway, the analytic solutions to elastic- plastic displacement of a circular cavity in homogeneous rock, and the rock parameters specified in current Chinese railway tunnel standards. Based on the analytical results and Hoek＇s unsupported rock-squeezing classification criteria, and considering the effect of support resistance, it introduces classification criteria with three deformation levels, which would be determined by indicators such as the relative deformation and strength- stress ratio in the design stage. A three-level verification standard, deformation management criteria, and countermeasure during the construction stage are put forward by using deformation value and deformation rate as the classification indicators. Tunnel deformation is controlled to a certain degree with the help of the research results.