高地应力地区隧道围岩分级研究

Rock Classification for Tunnels in High Geostress Areas

隧道围岩分级是隧道施工的重要指导依据,尤其在高地应力地区其对施工的影响是不可忽略的。文章首先介绍了地应力侧压力系数、最大水平主应力方向与洞轴线的夹角α对隧道围岩分级的影响情况,然后通过增加最大主应力方向与洞轴线夹角指标对地应力进行了修正,并且在公路隧道设计规范的基础上,对Ⅲ,Ⅳ和Ⅴ级围岩增加了亚级分级,更准确地对隧道围岩分级进行了定级。在此基础上,以谷竹高速公路大坪山隧道为工程实例,利用考虑增加地应力大小及方向的方法对其围岩分级进行了修正,得到了与实际开挖较相符的结果。

Surrounding rock classification is key for guiding tunnel construction, and its effect on tunnel construction in high geostress areas is fairly significant. Firstly, the influences of the lateral pressure coefficient of the geostress and the included angle between the maximum horizontal principle stress orientation and the tunnel axis on the classification of tunnel surrounding rock are presented in this paper; secondly, the geostress is corrected by increasing the included angle between the maximum principle stress orientation and the tunnel axis;and lastly, based on the Code for Design of Road Tunnels, the sub-classification is supplemented regarding rock masses of grades III, IV and V to achieve a more precise classification of tunnel surrounding rock. Using the Dapingshan tunnel on the Guzhu highway as an example, the surrounding rock classification is corrected by means of increasing the magnitude and orientation of the geostress, with results that are consistent with those of practical excavation.