Wu Gen-Shui, Yu Wei-Jian, Zuo Jian-Ping, Li Chun-Yuan, Li Jie-Hua, Du Shao-Hua
School of Mechanics and Civil Engineering, China University of Mining and Technology, Beijing, 100083, China.
State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Beijing, 100083, China.
Sci Rep. 2020 May 5;10(1):7556. doi: 10.1038/s41598-020-64513-3.
Coal and rock burst are one of the main dynamic disasters that affect coal mine production. In this paper, the burst structural model of the rock-coal-bolt (RCB) system and the burst tendency criterion are established on the background of deep thin coal seam mining. Uniaxial and triaxial mechanical tests under different stress states are carried out on RCB specimens with different angles. Combined with thermal imaging, the mechanical behavior of the inclined RCB specimen under uniaxial loading is discussed. The results show that the burst tendency of the RCB specimen increases with the angle. The stress-strain curves of some uniaxial and triaxial test specimens show two or more peaks, and the thermal imaging evolutionary process shows that the cracks of the coal and rock develop from shear to tension shear cracks. There is a further development of fracture and energy accumulation between the first and second peaks in the stress-strain curve of the specimen. Therefore, the failure degree of the second peak of the specimen may be stronger than that of the first peak. Additionally, the established stiffness coefficient and burst energy index can better describe the burst tendency of the RCB specimen under different stress states. The results show that the burst tendency of the RCB specimen under the triaxial test is much higher than that of the uniaxial test. In other words, it also explains that the essence of the burst failure of the surrounding rock in the roadway is the initial instability induced by the inside surrounding rock in the roadway. Moreover, the burst tendency is the largest when the rock and coal combination angle is 15°, and the burst damage range may also be increased by the failure of internal coal and rock mass.
煤岩动力灾害是影响煤矿生产的主要动力灾害之一。本文以深部薄煤层开采为背景，建立了煤岩-锚杆（RCB）系统的冲击结构模型和冲击倾向性判据。对不同角度的RCB试件进行了不同应力状态下的单轴和三轴力学试验。结合热成像技术，探讨了倾斜RCB试件在单轴加载下的力学行为。结果表明，RCB试件的冲击倾向性随角度的增大而增大。部分单轴和三轴试验试件的应力-应变曲线出现两个或更多峰值，热成像演化过程表明，煤岩裂纹从剪切裂纹发展为拉剪裂纹。试件应力-应变曲线的第一峰值和第二峰值之间存在断裂和能量积累的进一步发展。因此，试件第二峰值的破坏程度可能比第一峰值更强。此外，所建立的刚度系数和冲击能量指标能够更好地描述RCB试件在不同应力状态下的冲击倾向性。结果表明，三轴试验下RCB试件的冲击倾向性远高于单轴试验。换句话说，这也说明了巷道围岩冲击破坏的本质是巷道内部围岩引起的初始失稳。而且，当煤岩组合角度为15°时冲击倾向性最大，内部煤岩体的破坏也可能增大冲击破坏范围。
