Energy Evolution Characteristics of Coal-Rock Composite Bodies Based on Unidirectional Load

Taking coal mine dynamic disaster as research background in this paper, five samples of coal-rock composite bodies (CRCBs) with different coal thicknesses were designed, and the uniaxial loading tests were carried out on them by using the MTS uniaxial loading instrument and the DS5 acoustic emission instrument, and the damage process of the samples were analyzed from the perspective of energy conversion. The results were as follows. With increase in coal thickness of CRCBs, the uniaxial compressive strength and elastic modulus of CRCBs decreased while the peak strain increased, and the overall bearing capacity of the samples decreased, resulting in a decreasing trend of AE peak ringing count and peak energy. According to the theory of conservation of energy, it was found that the dissipated energy of the samples in the compaction stage accounted for a large proportion, and the elastic stage was dominated by the accumulation of elastic energy. After the plastic stage, the energy conversion rate in the samples accelerated, and the dissipated energy increased rapidly, leading to the gradual failure of the samples. The energy storage limit of samples decreased logarithmically together with increase in coal thickness. Finally, it was found that coal was the main energy storage structure of the whole coal and rock composite system by analyzing the energy accumulation mechanism of coal and rock composite structure in practical engineering. Therefore, to prevent and control underground dynamic disaster in practical engineering, the internal energy storage of a coal seam should be released and the clamping effect of roof and floor on coal body should be weakened. The achievements of this study will be a theoretical guidance for preventing and controlling dynamics.