原煤弹塑性局部化损伤本构模型研究

Study on the elasto-plastic localized damage constitutive model of raw coal

  • 摘要: 由于煤岩的非均质性,其内部微裂纹的萌生、扩展和聚合形成局部宏观裂纹导致最终失稳破坏。本文基于Mohr-Coulomb破坏准则,考虑局部化损伤效应,建立了原煤弹塑性局部化损伤本构模型。通过损伤演化作为内在驱动变量控制屈服面的膨胀收缩,描述煤岩的应变硬化、软化行为。采用指数函数形式损伤准则描述岩石断裂破坏过程中损伤演化行为,建立了局部带尺寸与损伤变量之间关系。通过数值模拟结果与原煤三轴试验数据对比论证提出模型的有效性。结果表明:该模型能过较好地捕捉原煤加载过程中主要的非线性变形特征,且峰后应变软化现象是局部化损伤快速增加所致。因此,本文提出的本构模型能够反映原煤的局部化变形破坏力学特征,相关研究工作可以为深部岩石工程理论模型研究提供新的研究思路。

     

    Abstract: Due to the heterogeneity of raw coal, the initiation, propagation, and aggregation of internal microcracks lead to the formation of local macroscopic cracks, ultimately causing instability and failure. Based on the Mohr-Coulomb failure criterion and considering the localized damage effect, this study establishes a constitutive model for raw coal with coupling elasto-plastic localized damage. Damage evolution is used as an internal driving variable to control the expansion and contraction of the yield surface, describing the strain hardening and softening behavior of the coal rock. An exponential function form of damage criterion is employed to describe the damage evolution during the rock fracturing process and establish the relationship between the changing localized band size and the damage variable. By comparing numerical simulation results with raw coal triaxial test data, the effectiveness of the proposed model is demonstrated. The results show that the model can adequately capture the main nonlinear deformation characteristics during the loading process of raw coal, and post-peak strain softening phenomenon is attributed to the rapid increase in localized damage. Therefore, the proposed constitutive model can reflect the mechanical characteristics of localized deformation and failure of raw coal, providing new research ideas for theoretical model studies in deep rock engineering.

     

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