基于挪威准则的有压引水隧洞围岩多方向稳定判别方法OA

To address the difficulty in characterizing the directional effects in the stability evaluation of surrounding rock for pressurized water conveyance tunnels under complex topographic conditions,a multi-directional stability criterion for surrounding rock was proposed.Based on the fundamental concept of the Norwegian criterion,the stability analysis of surrounding rock was extended from vertical overburden-controlled conditions to the mechanical analysis of rock columns in arbitrary directions.Considering the self-weight of rock columns,internal water pressure,seepage effects,and rock mass frictional resistance,an analytical expression for the minimum rock cover thickness was de-rived.Subsequently,a minimum rock cover cone model was established,and a unified multi-directional stability evaluation method was de-veloped to comprehensively assess the cover conditions in all directions along the tunnel axis.The proposed method was verified through theo-retical analysis and numerical simulations under a benchmark case,followed by a parametric sensitivity analysis.The results indicate that the minimum rock cover thickness exhibits an evident non-monotonic variation with direction,and the most unfavorable direction is located within the inclined range.Internal water pressure and internal friction angle primarily affect the magnitude of the required cover thickness but have limited influence on the distribution characteristics of the most unfavorable direction.