Song Zongwu, Tang Chun'an, Liu Hongyuan
School of Resources and Civil Engineering, Northeastern University, Shenyang 110819, China.
State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China.
Materials (Basel). 2025 Jun 21;18(13):2940. doi: 10.3390/ma18132940.
As a part of the mining-induced stress redistribution process during coal mining, the repeated loading and unloading process with increasing peak stresses will cause more severe deformation and damage to mining roadways, which is different from the findings in other underground engineering practices. Consequently, cyclic triaxial compression tests with increasing amplitudes were carried out to investigate the mechanical behavior, acoustic emission (AE) characteristics, and damage evolution of coal materials. It is found that peak deviatoric stress and axial residual strain at the failure of coal specimens increase with increasing confining pressures, while the changes in circumferential strain are not obvious. Moreover, the failure patterns of coal specimens exhibit shear failure due to the constraint of confining pressures while some local tensile cracks occur near the shear bands at both ends of the specimens. After that, the damage evolution of coal specimens was analyzed against the regularity of AE counts and energies to develop a damage evolution model. It is concluded that the damage evolution model can not only quantify the deformation and failure process of the coal specimens under cyclic loads with increasing amplitudes but also takes into account both the initial damage due to natural defects and the induced damage by the cyclic loads in previous cycles.
作为煤炭开采过程中采动应力重新分布过程的一部分，随着峰值应力增加的反复加卸载过程会对采动巷道造成更严重的变形和破坏，这与其他地下工程实践中的发现不同。因此，进行了振幅递增的循环三轴压缩试验，以研究煤体材料的力学行为、声发射（AE）特性和损伤演化。研究发现，煤样破坏时的峰值偏应力和轴向残余应变随围压增加而增大，而环向应变变化不明显。此外，由于围压的约束，煤样的破坏模式表现为剪切破坏，同时在试样两端的剪切带附近出现一些局部拉伸裂纹。之后，根据声发射计数和能量的规律分析了煤样的损伤演化，建立了损伤演化模型。结果表明，该损伤演化模型不仅可以量化振幅递增循环荷载作用下煤样的变形和破坏过程，而且考虑了天然缺陷引起的初始损伤和前一循环中循环荷载引起的诱导损伤。
