合理的强度准则在幂强化-理想塑性模型圆形隧洞围岩弹塑性分析中十分重要。为了得到适合该模型的强度准则,首先对4种常用岩土材料强度准则进行归纳总结,进而得到平面应变统一线性方程;然后考虑渗流影响,推导了幂强化-理想塑性模型圆形隧洞围岩处于塑性区、幂强化区时的应力、位移及塑性区半径的统一解;最后探讨了强度理论效应、幂强化参数和孔隙水压力对圆形隧洞围岩弹塑性分析的影响。研究结果表明:圆形隧洞围岩强度理论效应显著,经与有限元分析对比,应推荐使用Mogi-Coulomb准则、统一强度理论(b=1/2,c=0)准则、统一强度理论(b=1,c=0)准则;其次可使用内接圆DP2准则、等面积圆DP4准则,不建议使用内切圆DP3准则、Mohr-Coulomb准则,谨慎使用外接圆DP1准则、统一强度理论(b=1,c=1)准则;幂强化参数中幂强化系数m值对塑性区半径无影响,而塑性区位移随m值减小而增大,围岩塑性区半径和位移均随幂强化指数n值增大而增大;塑性区半径、径向应力和切向应力峰值均随孔隙水压力增大而增大。研究结果可为应变强化效应较强的圆形隧洞围岩支护设计提供重要的理论依据。

Reasonable strength criterion is of vital importance in the elastic-plastic analysis of surrounding rock of circular tunnel using power hardening-ideal plastic model. In the aim of obtaining a strength criterion suitable for the power hardening-ideal plastic model, first of all the four commonly used strength criteria for geotechnical materials were summarized; the unified linear equation of plane strain was acquired; then the unified solutions of stress, displacement and plastic zone radius of circular tunnel's surrounding rock in plastic zone and power hardening zone in the presence of seepage were deduced; and finally the theoretical strength effect, power hardening parameters, and pore water pressure on the elastic-plastic analysis of circular tunnel's surrounding rock were discussed. Research results revealed outstanding theoretical strength effect. Comparison with finite element analysis results suggest that Mogi-Coulomb criterion, unified strength theory with parameters b=1/2 and c=0, unified strength theory with parameters b=1 and c=0 are favorable; inscribed circle DP2 criterion and equivalent area circle DP4 criterion could follow in sequence; DP3 criterion and Mohr-Coulomb criterion are not recommended; circumscribed circle DP1 criterion and unified strength theory with parameters b=1 and c=1 should be used with caution. Among the power hardening parameters, the power hardening coefficient m had no impact on the radius of plastic zone, but the plastic zone displacement increased with the reduction of m; the plastic zone radius and displacement of surrounding rock both swelled with the growth of power hardening index n. The plastic zone radius, radial stress and tangential stress augmented with the climbing of pore water pressure. The research results offer an important theoretical basis for the support design of circular tunnel's surrounding rock with strong strain hardening effect.