The generalized Zhang–Zhu (GZZ) strength criterion has a high associated fitting accuracy for true triaxial test data. It makes direct use of the parameters of the Hoek–Brown criterion and has become one of the strength criteria recommended by the International Society for Rock Mechanics (ISRM). In this study, a new version of the GZZ criterion is developed by addressing the problems associated with the original version’s non-smoothness and non-convexity on the π plane. (i) The new criterion is smooth and derivable on the π plane with no numerical singularity in the strength calculation. It thus renders the application of complicated Lode dependence functions for modification of the non-smooth GZZ criterion unnecessary. (ii) The new criterion is non-convex only under the triaxial extension stress condition, which is not critical for those criteria developed from the Hoek–Brown strength criterion. The new criterion is transformed from incomplete convexity to full convexity with an increase in hydrostatic pressure I₁. Additionally, there exists a critical transformation radius r₀, which only relates to I₁. The new criterion achieves full convexity when I₁ is high and the quality of the rock mass is poor. (iii) Both the new criterion and the GZZ criterion have high fitting accuracy for rock strength data. Their fitting accuracy is much higher than that of the Pan–Hudson criterion. However, the fitted strength parameter m of the new criterion is closer to Hoek’s recommendation than that of the GZZ criterion, thus proving that the new criterion is applicable and reliable when used for rock strength calculation based on the Hoek–Brown criterion parameter system.

广义Zhang-Zhu (GZZ) 强度准则对于真正的三轴试验数据具有很高的相关拟合精度。它直接利用Hoek-Brown准则的参数，已成为国际岩石力学学会（ISRM）推荐的强度准则之一。在本研究中，通过解决与原始版本在π平面上的非光滑性和非凸性相关的问题，开发了新版本的 GZZ 准则。(i) 新准则在π上平滑且可推导在强度计算中没有数值奇点的平面。因此，不需要应用复杂的 Lode 相关函数来修改非平滑 GZZ 准则。(ii) 新准则仅在三轴拉伸应力条件下是非凸的，这对于从 Hoek-Brown 强度准则发展而来的那些准则并不重要。随着静水压力I ₁的增加，新的标准从不完全凸性转变为完全凸性。此外，还存在一个临界变换半径r ₀，它只与I _{1 相关}。当I ₁时，新准则实现全凸性高，岩体质量差。(iii) 新准则和GZZ准则对岩石强度数据拟合精度高。它们的拟合精度远高于 Pan-Hudson 准则。但新准则的拟合强度参数m比GZZ准则更接近Hoek推荐的强度参数，证明新准则用于基于Hoek-Brown准则参数体系的岩石强度计算时是适用的和可靠的。