单轴压缩下不同倾角煤岩组合体力学特性及破坏特征

Mechanical properties and failure characteristics of coal rock combinations with different inclination angles under uniaxial compression

为探究不同倾角下煤岩组合体失稳诱发冲击地压机制,利用颗粒离散元程序对0、15、30、45、60°这5组不同倾角煤岩组合体进行单轴压缩试验。研究结果表明:煤是煤岩组合体失稳破坏的主体;当煤岩组合体的倾角分别由0°增加至30°和由30°增加到60°时,煤岩组合体的单轴抗压强度分别下降2.01%和9.59%,细观裂纹数量分别下降22.9%和4.0%,声发射信号出现时间提前,说明倾角的增大导致煤岩组合体单轴抗压强度降低,失稳破坏时间提前但破坏程度降低;在单轴加载初期,不同倾角组合体界面处煤岩颗粒向界面处运动导致界面处存在扩容趋势,倾角影响界面附近煤岩颗粒的运动进而导致组合体破坏区域逐渐由煤体向煤岩交界面过渡;当煤体裂纹扩展至煤岩界面时,高倾角煤岩组合体产生的界面滑移效应导致其破坏形式由压剪破坏转变为滑移破坏,且30°倾角为分界线。

In order to explore the mechanism of rock burst induced by the instability of coal rock combinations under different dip angles,a particle discrete element program was used to conduct uniaxial compression tests on five sets of coal and rock combination models with different dip angles:0,15,30,45 and 60°.The research results indicate that coal is the main cause of instability and failure in coal-rock combinations.When the dip angle of the coal-rock combination increased from 0°to 30°and from 30°to 60°,the uniaxial compressive strength of the coal-rock combination decreased by 2.01%and 9.59%,and the number of microscopic cracks decreased by 22.9%and 4.0%,respectively.The appearance time of the acoustic emission signal is advanced,indicating that the increase in dip angle led to a decrease in the uniaxial compressive strength of the coal-rock combination,and the instability failure time is advanced,but the degree of failure is reduced.In the early stage of uniaxial loading,the movement of coal and rock particles at the interface of different dip angle combinations led to an expansion trend at the interface.The dip angle affected the movement of coal and rock particles near the interface,leading to a gradual transition of the failure area of the combination from the coal body to the coal-rock interface.When the cracks in the coal body extend to the coal-rock interface,the interface slip effect generated by the high dip angle coal-rock combination causes its failure mode to change from compression shear failure to slip failure,with a 30°dip angle as the boundary.