围压作用下煤岩材料超声致裂规律研究

当超声波在煤岩固体材料中传播时，受其机械效应，煤岩基质固体颗粒间相互作用。从超声波的机械效应角度结合断裂力学，对围压影响的超声激励破岩机制进行探讨，利用 RFPA2D 岩石破裂过程分析系统对超声激励不同围压下煤岩致裂过程进行了数值试验验证。研究表明：围压降低了煤岩内部裂纹的断裂强度因子，改变裂纹尖端应力场；围压对煤岩破裂具有抑制作用，在相同功率超声作用下，围压越大，超声激励碎岩程度越低；数值实验表明，随着围压增加，超声致裂煤岩影响区域逐渐减小，煤岩破坏形式由低围压下的张拉和剪切破坏共同作用逐渐向高围压下单一剪切破坏过渡。相同有效声压作用下，煤岩破裂过程中主应力随煤岩围压升高而增大。

Research on Ultrasound Cracking Law of Coal Materials Under Confining Pressure

When the ultrasound propagates in coal solid materials,affected by mechanical effects,coal matrix particles interact.In terms of the mechanical effect of ultrasound and fracture mechanics,the mechanism of breaking coal by ultrasonic stimulation of confining pressure is discussed,and the mechanism is verified by numerical experi-ment of the process of ultrasound irradiation coal cracking under different confining pressure by using RFPA2D.The result shows that the confining pressure reduces the fracture strength factor of internal cracks in coal,and changes the crack tip stress field.The confining pressure has an inhibitory effect on coal rock fracture.At the same ultrasound ir-radiation power input,the larger the confining pressure is,the lower fragmentation degrees is.The numerical experi-ment results show that,with the rise of the confining pressure,the ultrasound cracking affected area decreases gra-dually,and the failure form of the coal transitions from tensile and shear failure combined action under low confining pressure to single shear failure under high confining pressure.Under the same effective sound pressure,the principal stress increases with the rise of the confining pressure in the process of coal failure.