煤样贯穿节理对岩-煤组合体强度及破坏特征影响模拟研究

Simulation study on effects of coal persistent joint on strength and failure characteristics of rock-coal combined body

通过颗粒流数值模拟实现了煤样含贯穿节理岩-煤组合体单轴压缩试验,研究了煤样贯穿节理对岩-煤组合体强度及破坏特征影响。结果表明:煤样含贯穿节理岩-煤组合体单轴抗压强度σ、弹性模量E、峰值应变ε、起裂应力σci及损伤应力σcd均小于完整组合体;但E随贯穿节理与竖直方向夹角α变化不明显,接近完整组合体弹性模量,同时当α为0°,75°,90°时,σ,ε,σci,σcd与完整组合体相差不大;随α增大,σ,ε,σci,σcd均先递减再增大,当α为45°时,σ,ε,σcd最小,与完整组合体相比,分别递减了72.77%,68.28%,74.43%;而当α为15°时,σci最小,与完整组合体相比,递减了66.13%。煤样贯穿节理加速了岩-煤组合体从裂纹不稳定扩展向宏观失稳转变,大部分煤样含贯穿节理岩-煤组合体破坏发生在煤样内,岩样未发现明显破坏,其破坏模式主要包括"V"型穿节理面剪切破坏、部分沿节理面剪切破坏、沿节理面剪切破坏及复合式破坏模式;当α为30°时,岩-煤组合体发生整体性破坏,煤样沿节理面剪切破坏,而岩石由于节理尖端裂纹扩展而发生拉伸破坏。

Numerical simulations for the rock-coal combined body with a coal persistent joint are conducted using the particle flow simulation. Effects of the coal persistent joint on strength and failure characteristics of the rock-coal combined body are studied and analyzed. The results show that the uniaxial compressive stress σ, the elastic modulus E, the peak strain ε, the crack initiation stress σci and the damage stress σcd of the combined body with a coal persistent joint are less than those of the intact combined body. However, with increasing α between the coal persistent joint direction and the vertical direction, the E does not change significantly. E of the combined body with a coal persistent joint is close to that of the intact combined body. When α is 0°, 75° or 90°, σ, ε, σci and σcd have small differences with those of the intact combined body. Moreover, with increasing α, σ, ε, σci and σcd decrease firstly and then increase later. σ, ε and σcd at α of 45° is the lowest, comparing with the intact combined body, they decreases are 72.77%,68.28% and 74.42%, respectively. While σci at α of 15° is the lowest, decrease is 66.13% compared to the intact combined body. Additionally, the coal persistent joint enhances the transformation of the combined body from unstable the crack expansion to the macroscopic instability. A majority of failures for the combined bodies with a coal persistent joint occur within the coal body and no obvious damage is observed in the rock body. Their failure patterns mainly are V-type shear failure crossing the joint plane, shear failure along partial joint plane, shear failure along the joint plane and multiple failures of shear and tensile failures. Meanwhile, when α is 30°, the failure in rock-coal combined body occurs as a whole one. The coal body occurs a shear failure along the joint plane and the rock is destroyed as a tensile failure propagating from joint tip.