由于煤岩含有多种层理构造, 在宏观上具有典型的横观各向同性特征, 对煤岩的损伤破坏及能量演化等具有显著影响。基于能量耗散理论, 推导不同层理倾角煤岩变形破坏过程的弹塑性应变、损伤变量及各能量表达式, 并建立考虑不同层理倾角的能量耗散−损伤本构模型, 定量表征了层理倾角与损伤变量、各峰值能量之间的对应关系, 探究了荷载作用下层理倾角对煤岩力学和能量响应特征的影响。研究结果表明: (1) 不同层理倾角煤岩的能量转换均呈现阶段性演化, 分别对应不同破坏阶段; 在恒轴压卸围压及不同围压三轴压缩条件下, 随层理倾角的增大, 峰值弹性能及耗散能均表现出先减小后增大的“U”形趋势, 与煤岩峰值强度随层理倾角的变化基本对应, 两种条件下层理倾角分别为60°~90°、45°~90°时变化最为敏感, 表现为能量角度的各向异性。(2) 根据不同层理倾角煤岩能量耗散过程, 进一步构建了考虑层理倾角的能量耗散−损伤本构模型, 并引用公开发表的试验数据进行验证和分析, 结果显示, 该模型能够较好地描述不同层理倾角煤岩在常规三轴压缩、恒轴压卸围压等荷载条件下的煤岩变形破坏特征, 表明所构建的模型具有较好的适用性。(3) 不同层理倾角煤岩耗散能U_d与损伤变量D的演化具有较好的一致性。随轴向应变的增大, 二者均经历了由缓到急再趋于平缓的过程, 总体呈“S”形变化趋势; 随层理倾角的增加, 损伤变量D与耗散能U_d均呈现出先减小后增加的“U”形趋势, 当层理倾角为90°时, 煤岩峰值耗散能U_d与损伤变量D均达最大值, 煤岩极易发生破坏。研究结果可为探寻矿压显现规律、煤巷帮部失稳诱发机理和防治冲击地压等矿井灾害提供参考。

The coal rock contains a variety of bedding structures, and typically shows transversely isotropic characteristics at the macroscopic level, which has a significant influence on the damage and energy evolution of the coal rock. Based on the energy dissipation theory, the elastic-plastic strains, damage variables and energy expressions for the deformation and damage process of coal rocks with different bedding dip angles were deduced, and the energy dissipation-damage constitutive model was established considering different bedding dip angles, which quantitatively characterizes the correspondence between bedding dip angles, damage variables and peak energies, and the effects of bedding dip angle on the mechanical and energetic response characteristics of coal rocks under loading were investigated. The results showed that the energy conversion of coal rock with different bedding dip angles showed a stage-by-stage evolution, corresponding to different damage stages; under the conditions of constant axial pressure unloading confining pressure and conventional triaxial loading with different confining pressures, the peak elastic energy and dissipation energy showed a U-shaped trend of decreasing and then increasing with the increase of bedding dip angle, which basically corresponds to the change of the peak strength of coal rock with the change of bedding dip angle. The changes of the peak strength of coal rock with the bedding dip angle basically corresponded to the changes of the bedding dip angle, and the changes were most sensitive when the bedding dip angle is 60°−90° and 45°−90° under the two conditions respectively, which is manifested in the anisotropy of the energy angle. According to the energy dissipation process of coal rocks with different bedding dip angles, the energy dissipation-damage constitutive model considering bedding dip angle was further constructed, and the published test data were quoted for verification and analysis. The results showed that the model can better describe the deformation and damage characteristics of coal rocks with different bedding dip angles under the loading conditions of conventional triaxial compression and constant axial pressure unloading confining pressure, which indicates that the constructed model has better applicability. The evolution of dissipation energy U_d and damage variable D of coal rocks with different bedding dip angles showed good consistency. With the increase of axial strain, both of them went through the process from slow to sharp and then tend to be gentle, showing a general “S” shaped change trend. With the increase of bedding dip angle, the damage variable D and dissipated energy U_d both showed a "U" trend of a first decrease and then increase, and when the bedding dip angle is 90°, coal rocks with different bedding dip angles have a "U" trend of decreasing and then increasing. When the dip angle of the bedding is 90°, the peak dissipation U_d and the damage variable D reached the maximum value, and the coal rock was extremely vulnerable to damage. The results of the study can be used as a reference for exploring the law of mine pressure behavior, the induced mechanism of coal roadway gang instability and the prevention of mine disasters such as pressure bump.