李峰, 毕明鑫, 张飞超, 等. 纵波模式下的煤岩体动态响应特性与损伤机理[J]. 煤炭学报, 2018, (5): 1272-1280. DOI: 10.13225/j.cnki.jccs.2018.0073
引用本文: 李峰, 毕明鑫, 张飞超, 等. 纵波模式下的煤岩体动态响应特性与损伤机理[J]. 煤炭学报, 2018, (5): 1272-1280. DOI: 10.13225/j.cnki.jccs.2018.0073
LI Feng, BI Mingxin, ZHANG Feichao, et al. Dynamic response characteristics and damage mechanisms of coal-rock masses under P-waves[J]. Journal of China Coal Society, 2018, (5): 1272-1280. DOI: 10.13225/j.cnki.jccs.2018.0073
Citation: LI Feng, BI Mingxin, ZHANG Feichao, et al. Dynamic response characteristics and damage mechanisms of coal-rock masses under P-waves[J]. Journal of China Coal Society, 2018, (5): 1272-1280. DOI: 10.13225/j.cnki.jccs.2018.0073

纵波模式下的煤岩体动态响应特性与损伤机理

Dynamic response characteristics and damage mechanisms of coal-rock masses under P-waves

  • 摘要: 以圆柱煤岩体为研究对象,基于纵波的传播特征与波动控制方程,得出了纵波传播的频率方程,建立了纵波模式下位移、应变、应力、振速与能量动态力学计算模型。仿真计算结果表明:低阶纵波模式下,圆柱煤岩体中应力波的振动较为平缓,可近似认为是准静力载荷作用,煤岩体以剪切破坏为主,而且初始破坏位置主要分布在圆柱煤岩体底面(作用面)且临近表面的区域。高阶纵波模式下,沿圆柱煤岩体径向方向,位移、应变、应力、振速及能量的振动幅值均随着半径无量纲的增大呈现出衰减趋势,大致符合幂函数关系;剪切应力、应变振幅的极值最大,能量衰减速度最快;而且值得注意的是径向、轴向应力/应变振动幅值随着半径无量纲增大逐渐趋于一致,而且方向趋于相反。由此分析可知:圆柱煤岩体在无围压条件下易发生脆性劈裂破坏,主要由拉应力导致;在有围压条件下易发生近似圆锥形破坏,主要属于拉剪破坏;圆柱煤岩体底面(作用面)圆心处的位移、应变、应力、振速及能量动态变化幅值均最大,因此煤岩体损伤破坏的初始位置应为此圆心处。

     

    Abstract: Coal and rock masses in deep mining would bear dynamic disturbances which propagated deeper into the coal rock mass in the form of stress wave. These stress waves were mainly composed of high order P-waves with high frequency,fast phase velocity and many wave numbers. Because of the absorption and dispersion effect in the propaga- tion of waves,the high order P-waves would change into low order P-waves with low frequency,slow phase velocity and less wave numbers. And the compressive and tensile stresses occur alternately,which could cause the strong vibration and serious damage of the coal and rock. Taking cylindrical coal and rock as an example,this paper obtained the fre- quency equation of P-waves,and established a dynamic calculation model for the displacement,strain,stress,vibration velocity and energy based on the propagation characteristics of P-waves and wave control equations. The simulation re- sults showed as follows:under the action of low order P-waves,the vibration of radial and shear stress waves were rela- tively gentle,which could be considered as an effect of quasi-static loading. Shear failure of coal-rock mass would mainly occur and distribute near the surface. Under the action of low order P-waves,the vibration amplitudes of dis- placement,strain,stress,vibration velocity and energy decreased with the increase of radius dimensionless along the ra- dial direction of the cylindrical coal rock,which followed the power function. The amplitudes of shear stress and strain were the largest,but the energy attenuation was the fastest. The authors noticed,most surprisingly,that the amplitude directions of the radial and axial stress waves were almost opposite,with the amplitude values basically same when the vibration kept stable. When there was no confining pressure,the cylindrical coal and rock mass eventually displayed crashing or splitting failure which was mainly caused by tensile stress. However,the conical failure easily occurred when there was confining pressure,which was tensile-shear failure. The maximum amplitude of displacement,strain, stress,vibration speed and energy were all located at the axis of action surface of the cylindrical coal and rock. There- fore,the initial damage position of coal and rock would be in the center of action surface.

     

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