PDF(Pubmed)
Abstract：
Coal seam drilling is a simple, economical, and effective measure commonly used to prevent and control rock burst. Following rock burst, coal exhibits significant dynamic characteristics under high strain-rate loading. Our purpose was to determine the physical processes associated with impact damage to drilled coal rock, and its mitigation mechanism. An impact test was carried out on prefabricated borehole coal specimens, and the impulse signals of the incident and transmission rods were monitored. The crack initiation, expansion, and penetration of coal specimens were video-recorded to determine the mechanical properties, crack expansion, damage modes, fragmentation, and energy dissipation characteristics of coal specimens containing different boreholes. The dynamic compressive strength of the coal specimens was significantly weakened by boreholes under high strain-rate loading; the dynamic compressive strength and the dynamic modulus of elasticity of coal rock showed a decreasing trend, with increasing numbers of boreholes and a rising and decreasing trend with increasing borehole spacing; the number and spacing of boreholes appeared to be design parameters that could weaken coal-rock material under high strain-rate loading; during the loading of coal and rock, initial cracks appeared and expanded in the tensile stress zone of the borehole side, while secondary cracks, which appeared perpendicular to the main crack, expanded and connected, destroying the specimen. As the number of boreholes increased, the fractal dimension (D) and transmission energy decreased, while the reflection energy increased. As the borehole spacing was increased, D decreased while the reflective energy ratio decreased and increased, and the transmissive energy ratio increased and decreased. Drilling under high strain modifies the mechanical properties of impact damaged coal rock.
摘要：
煤层钻孔是一个简单的，经济,以及预防和控制岩爆常用的有效措施。岩爆之后,煤在高应变率载荷下表现出显著的动态特性。我们的目的是确定与对钻孔煤岩的冲击破坏相关的物理过程，及其缓解机制。对预制钻孔煤样进行了冲击试验,并监测入射杆和传输杆的脉冲信号。裂纹萌生,扩展,并对煤样的渗透进行视频记录，以确定其机械性能，裂纹扩展,损伤模式,碎片化,和含不同钻孔的煤样的能量耗散特性。在高应变率加载下，钻孔显著削弱了煤样的动抗压强度，煤岩的动抗压强度和动弹性模量呈下降趋势。随着钻孔数量的增加和钻孔间距的增加，钻孔的数量和间距似乎是在高应变率加载下削弱煤岩材料的设计参数；在煤岩加载过程中，在钻孔侧的拉应力区出现并扩展了初始裂缝，而二次裂缝，它看起来垂直于主裂纹，扩展和连接，破坏标本.随着钻孔数量的增加，分形维数(D)和传输能量下降，而反射能量增加。随着钻孔间距的增加，d降低，而反射能量比降低和增加，透射能量比增加和减少。高应变下的钻探改变了冲击损伤煤岩的力学性能。
