Some rock joints exhibit significant brittleness, characterized by a sharp decrease in shear stress upon reaching the peak strength. However, existing models often fail to accurately represent this behavior and are encumbered by numerous parameters lacking clear mechanical significance. This study presents a new statistical damage constitutive model rooted in both damage mechanics and statistics, containing only three model parameters. The proposed model encompasses all stages of joint shearing, including the compaction stage, linear stage, plastic yielding stage, drop stage, strain softening stage, and residual strength stage. To derive the analytical expression of the constitutive model, three boundary conditions are introduced. Experimental data from both natural and artificial rock joints is utilized to validate the model, resulting in average absolute relative errors ranging from 3% to 8%. Moreover, a comparative analysis with established models illustrates that the proposed model captures stress drop and post-peak strain softening more effectively, with model parameters possessing clearer mechanical interpretations. Furthermore, parameter analysis is conducted to investigate the impacts of model parameters on the curves and unveil the relationship between these parameters and the mechanical properties of rock joints. Importantly, the proposed model is straightforward in form, and all model parameters can be obtained from direct shear tests, thus facilitating the utilization in numerical simulations.

中文翻译：

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基于统计损伤的脆性落下岩石节理剪切本构模型


一些岩石节理表现出明显的脆性，其特征是在达到峰值强度时剪切应力急剧降低。然而，现有模型往往无法准确表示这种行为，并且受到许多缺乏明确机械意义的参数的阻碍。本研究提出了一种新的统计损伤本构模型，该模型植根于损伤力学和统计学，仅包含三个模型参数。所提出的模型涵盖了节理剪切的所有阶段，包括压实阶段、线性阶段、塑性屈服阶段、下降阶段、应变软化阶段和残余强度阶段。为了推导出本构模型的解析表达式，引入了三个边界条件。利用来自天然和人工岩石节理的实验数据来验证模型，得出的平均绝对相对误差在 3% 到 8% 之间。此外，与已建立模型的比较分析表明，所提出的模型更有效地捕获了应力下降和峰后应变软化，模型参数具有更清晰的力学解释。此外，还进行了参数分析，研究了模型参数对曲线的影响，并揭示了这些参数与岩石节理力学性能之间的关系。重要的是，所提出的模型形式简单明了，所有模型参数都可以从直接剪切试验中获得，从而有利于在数值模拟中的应用。