Joint surface morphology has essential implications for joint shear behaviors. In this paper, constant normal load (CNL) direct shear tests were performed on 150 artificial rock joint specimens to study the joint surface degradation process under various initial joint roughness coefficient (JRC initial ), joint wall compressive strength (JCS), and normal stress ( σ n ) values. The experimental results revealed that with increases in JRC initial , JCS, and σ n , the joint surface exhibited different levels of increased degradation. With increasing shear displacement, the JRC continued to decline and finally tended to stabilize to a constant value, and we divided the degradation process into an initial weakening phase, a rapid weakening phase, and a constant weakening phase. Based on regression analyses, a JRC degradation model was presented to evaluate the JRC values of rock joints under various displacements, and a new empirical equation was introduced to predict peak shear displacement. Additionally, a piecewise function for the different shear displacement stages was proposed to calculate JRC mobilized by replacing JRC in the JRC–JCS model, and the variation in the friction angle $$\phi$$ ϕ at various stages was discussed. Finally, a modified constitutive model was developed to predict shear strength versus displacement curves. The predicted results indicated that the new proposed model performs better than previous models.

中文翻译：

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基于节理剪切过程中节理表面退化特征的岩石节理经验剪切强度判据

接头表面形态对接头剪切行为具有重要意义。本文对150个人造岩石节理试样进行恒法向载荷（CNL）直剪试验，研究不同初始节理粗糙度系数（JRC初始值）、节理壁抗压强度（JCS）和正应力下的节理面退化过程。 (σn) 值。实验结果表明，随着 JRC initial 、JCS 和 σ n 的增加，接合面表现出不同程度的退化增加。随着剪切位移的增加，JRC 继续下降，最终趋于稳定在一个恒定值，我们将降解过程分为初始弱化阶段、快速弱化阶段和恒定弱化阶段。根据回归分析，提出了一个 JRC 退化模型来评估不同位移下岩石节理的 JRC 值，并引入了一个新的经验方程来预测峰值剪切位移。此外，提出了不同剪切位移阶段的分段函数，通过替换 JRC-JCS 模型中的 JRC 来计算动员的 JRC，并讨论了不同阶段摩擦角 $$\phi$$ ϕ 的变化。最后，开发了一种改进的本构模型来预测剪切强度与位移曲线。预测结果表明，新提出的模型比以前的模型表现更好。提出了不同剪切位移阶段的分段函数来计算通过替换 JRC-JCS 模型中的 JRC 调动的 JRC，并讨论了不同阶段摩擦角 $$\phi$$ ϕ 的变化。最后，开发了一种改进的本构模型来预测剪切强度与位移曲线。预测结果表明，新提出的模型比以前的模型表现更好。提出了不同剪切位移阶段的分段函数来计算通过替换 JRC-JCS 模型中的 JRC 调动的 JRC，并讨论了不同阶段摩擦角 $$\phi$$ ϕ 的变化。最后，开发了一种改进的本构模型来预测剪切强度与位移曲线。预测结果表明，新提出的模型比以前的模型表现更好。