关键词: 动载荷, 构造煤体, 卸载波, 动态损伤机制, 动力响应

Abstract: Based on the theory of stress wave propagation and interaction, the propagation process and damage mechanism of coal are studied when stress wave propagates through the coal comprising plastic coal, elastic coal, tectonic coal and initial coal in front of the tunneling. Furthermore, the dynamic response of tectonic coal is revealed. The results show that the main tensile stresses distribute centrally in coal regions, where the wave impedance changes under dynamic loading. It is also found that the maximum tensile stress is around the interface of plastic and elastic coal. In addition, the occurrence of tensile stress is closely related to the unloading wave, which result in the tensile-shear failure of coal in combination with the effect of in-situ stress. It is clearly shown that the carrying capability of tectonic coal to dynamic loading is weak. Due to the existence of tectonic coal, the strong tensile stress is generated in elastic coal under unloading stress waves, which easily leads to heavy damage in some parts of elastic coal. Stress waves are frequently reflected and transmitted in loading and unloading processes and consequently multi-beam unloading waves are produced. Under the effect of such unloading waves, the formation of tensile stress area in the vicinity of coal bed results in the spalling phenomenon at the moment of coal and gas outbursts. This study has theoretical significance as it contribute to controlling and preventing the dynamic disasters of coal and rock in mine.

Key words: dynamic loading, tectonic coal, unloading stress wave, dynamic damage mechanism, dynamic response