Buertai Coal Mine, China Energy Shendong Coal Group Co., Ltd.
Shendong Coal Technology Research Institute, China Energy Shendong Coal Group Co., Ltd.

为探明循环应力损伤作用对煤体动态断裂特性的影响,对原始及循环应力损伤后的煤体I型单边缺口梁试件进行了静态与动态断裂试验研究。通过试验得到:煤体平均动态I型断裂韧度(KIC)为0.344MPa·m1/2,平均I型断裂能(GC)为66.99N/m,较静态煤断裂参数分别提高了1.38倍与1.26倍;经循环应力损伤后煤试件的平均静态KIC值为0.219MPa·m1/2,平均静态GC为44.26N/m,较原始煤试件分别降低了12.05%与16.74%;平均动态KIC为0.279MPa·m1/2,平均动态GC为52.72N/m,与原始煤试件冲击断裂试验结果相比,分别降低了20.90%与21.30%。试验结果表明,循环应力对煤体的动静态断裂力学参数均具有劣化影响,且煤试件动态断裂力学参数的劣化程度更高,证明煤体动态断裂行为对循环应力损伤作用更加敏感。同时,原始及循环应力损伤后煤试件动态断裂破坏的分形维数分别为1.32与1.21,即原始煤试件在冲击载荷作用下断裂破碎的更加复杂,冲击动力学显现的更加充分。此外,基于黏聚裂纹模型的煤体I型动态断裂数值计算结果与试验结果相符,表明黏聚裂纹模型能够对煤体动态断裂过程进行有效表征。研究成果可为具为相似特性的煤体提供参考。

To investigate the impact of cyclic stress damage on the dynamic fracture characteristics of coal mass-es, static and dynamic fracture tests were conducted on type I single-sided notched beam specimens of coal both prior to and following cyclic stress damage. The test results revealed that the average dynamic mode I fracture toughness (KIC) of the coal mass stands at 0.344 MPa·m1/2, with an average mode I fracture energy (GC) of 66.99 N/m. These figures are respectively 1.38 and 1.26 times higher than those measured for the static fracture parameters of the coal specimens. After expore to cyclic stress damage, the average static KIC value of the coal specimen was reduced to 0.219 MPa·m1/2, and the average static GC to 44.26 N/m, marking decreases of 12.05% and 16.74% relative to the original specimens. Additionally, the average dynamic KIC and GC values decreased to be 0.279 MPa·m1/2 and 52.72 N/m, respectively, representing reductions of 20.90% and 21.30% compared with the impact fracture test results of the untreated coal specimens. These findings suggest that cyclic stress detrimen-tally affects both the dynamic and static fracture mechanical parameters of coal masses, with dynamic fracture parameters exhibiting a greater degree of degradation. This highlights the enhanced sensitivity of coal mass dy-namic fracture behavior to cyclic stress damage. Furthermore, fractal analysis of the dynamic fracture damage yielded dimensions of 1.32 for untreated specimens and 1.21 for those subjected to cyclic stress damage, indicat-ing a more complex fracture and fragmentation process under impact loading for the former. Numerical calcula-tions based on the cohesive crack model for type I dynamic fracture of coal masses align well with experimental results, underscoring the model's effectiveness in capturing the dynamic fracture process of coal masses. These insights provide a reference for coal masses with similar characteristics.

张传玖,李果,任建慧,等.循环应力损伤对煤体I型动态断裂特性的影响[J].采矿与岩层控制工程学报,2024,6(2):023031.

ZHANG Chuanjiu, LI Guo, REN Jianhui, et al. Effect of cyclic stress damage on the mode I dynamic fracture characteristics of coal[J]. Journal of Mining and Strata Control Engineering, 2024, 6(2): 023031.