围压与冲击扰动作用下组合煤岩超低摩擦效应分析

ANALYSIS OF ULTRA-LOW FRICTION EFFECT OF COAL-ROCK COMBINATION BLOCK UNDER CONFINING PRESSURE AND IMPACT DISTURBANCE

深部煤岩在垂直扰动作用下发生振动,当水平冲击足以克服块体间摩擦阻力时,极易发生超低摩擦型冲击地压。文章以细砂岩-煤-细砂岩组合块体为研究对象,考虑顶板-煤-底板临近工作面开采工况,采用数值模拟方法,建立围压与冲击扰动下组合煤岩数值模型,以煤块水平位移、垂直加速度差值作为超低摩擦效应特征参数,分析围压、垂直冲击及水平冲击对特征参数的影响规律。研究结果表明:在垂直冲击与围压共同作用下,煤岩体残余位移及水平位移峰值随围压增大且呈指数增长趋势;在垂直冲击、水平冲击和围压三者共同作用下,煤岩体超低摩擦效应强度与作用时间都随着围压呈增加趋势;垂直冲击对组合煤岩超低摩擦效应的影响最为显著。

The deep coal-rock combinations vibrate under the action of vertical disturbance. When the horizontal impact overcomes the friction resistance between blocks, it is very easy to produce ultra-low friction rock burst. In this paper, the combination block of fine sandstone-coal-fine sandstone is regarded as the research object. Considering the mining condition of the roof-coal-floor near the working face, numerical simulation method was used to establish the numerical block model under confining pressure and impact disturbance. The horizontal displacement and vertical acceleration difference value of coal block are defined as characteristic parameters of ultral-low friction effect. The influence of confining pressure, vertical impact and horizontal impact on the characteristic parameters are analyzed. The results show that the residual and horizontal displacement peaks increase exponentially with the increase of confining pressure under the interaction of vertical impact and confining pressure. And under the interaction of vertical and horizontal impacts and confining pressure, the strength and duration of ultra-low friction effect also increase with the increase of confining pressure. The vertical impact has the most significant effect on the ultra-low friction effect in coal-rock combination block.