深埋隧道应变软化弹塑性解的强度准则效应

Strength criterion effect on elasto-plastic solution of deep tunnels considering strain softening characteristics

为了探究强度准则效应对应变软化隧道围岩稳定性的影响,总结隧道围岩分析中常用强度准则表达式,归纳出常用强度准则的统一方程,并结合应变软化模型与非关联流动法则,推导出隧道围岩应力场、塑性区范围及位移的计算方法。研究结果表明:应变软化隧道围岩的强度准则效应显著,内角点外接圆DP(Drucker−Prager)准则、内切圆DP准则、等面积圆DP准则、匹配圆DP准则及Mohr−Coulomb准则对应的结果普遍偏于保守;统一强度理论(b=1)与外角点外接圆DP准则所得结果相对偏于危险;不考虑岩体剪胀特性时会导致所得结果偏于危险。工程应用中,建议优先采用Mogi−Coulomb准则或统一强度理论(b=1/2),并合理考虑围岩剪胀特性,以更好地揭示围岩稳定性问题。

In order to explore the effect of strength criterion on the stability of the surrounding rock of strain softening tunnel,the expressions of the common strength criteria in the analysis of the tunnel surrounding rock were summarized,and the unified equation of common strength criteria was proposed.Combined with the strain softening model and non-associated flow rule,the calculation method of the stress field,plastic zone and displacement of the surrounding rock of the tunnel was derived.The results show that the strength criterion effect of the surrounding rock in strain softening tunnel is significant.The calculation results of the inner corner circumscribed circle DP(Drucker−Prager)criterion,inscribed circle DP criterion,equivalent area circle DP criterion,matching circle DP criterion and Mohr−Coulomb criterion are generally conservative.The calculation results of unified strength theory with parameter b=1 and external corner circumscribed circle DP criterion are relatively dangerous.Without considering dilatancy characteristics can result in dangerous calculation results.In engineering applications,the Mogi−Coulomb criterion or unified strength theory with parameter b=1/2 should be preferentially adopted,and the dilatancy characteristics of surrounding rock should be considered reasonably to reveal the stability of surrounding rocks.