煤表面粗糙度对煤岩超低摩擦效应影响试验研究

Experimental Study on the Influence of Coal Surface Roughness on the Ultra-Low Friction Effect of Coal Rock

超低摩擦型冲击地压本质是煤岩界面发生超低摩擦效应诱发的一种新型煤矿动力灾害,以沈阳红阳三矿顶板-煤层-底板为研究对象,利用自主研发的试验装置进行了轴压、垂直扰动和水平冲击共同作用下砂岩-煤-砂岩叠加块体超低摩擦效应模拟试验,以煤块为工作块体,分析了煤表面粗糙度对工作块体水平位移幅值、水平位移突变时间、水平加速度幅值、水平加速度突变时间的影响,得到了煤表面粗糙度对超低摩擦效应影响规律。结果表明:(1)砂岩表面粗糙度系数一定时,随煤表面粗糙度系数增大,工作块体水平位移和水平加速度时间历程曲线存在三阶段特征,即孕育阶段、激发阶段、稳定阶段;(2)煤表面粗糙度系数存在拐点为3.98,当煤表面粗糙度小于拐点3.98时,随煤表面粗糙度增大,激发阶段水平位移大于稳定阶段水平位移,位移差线性减小,超低摩擦效应减弱;(3)当煤表面粗糙度大于拐点3.98时,随煤表面粗糙度增加,激发阶段水平位移小于稳定阶段水平位移,此时工作块体水平位移出现二次增加,随位移差绝对值不断增大,超低摩擦效应越显著;(4)水平位移幅值和水平加速度幅值随煤表面粗糙度增大,呈先线性递减后线性递增规律;(5)水平位移突变时间和水平加速度突变时间随煤表面粗糙度增加,呈先线性增加后线性递减规律。

The ultra-low friction rock burst is essentially a new type of coal mine dynamic disaster induced by the ultra-low friction effect at the coal-rock interface.Taking Shenyang Hongyang San Mine roof-coal seam-bottom slab as the research object,and a simulation test of ultra-low friction effect of sandstone-coal-sandstone superimposed block under the joint action of axial pressure,vertical disturbance and horizontal impact was carried out the self-developed test device.The effect of coal surface roughness on the horizontal displacement amplitude,horizontal displacement abrupt change time,horizontal acceleration amplitude and horizontal acceleration abrupt change time of the working block was analyzed,and was obtained the influence law of coal surface roughness on the ultra-low friction effect.The results show that:(1) When the sandstone surface roughness is constant,with the increase of the coal surface roughness,the horizontal displacement and horizontal acceleration time history curve of the working block has three-stage characteristics,namely the incubation stage,the excitation stage,and the stable stage;(2) The coal surface roughness has an inflection point of 3.98.When the coal surface roughness is less than the inflection point of 3.98,as the coal surface roughness increases,the horizontal displacement in the excitation stage is greater than the horizontal displacement in the stable stage,the displacement difference decreases linearly,and the ultra-low friction effect weakens;(3) When the coal surface roughness is greater than the inflection point of 3.98,with the increase of the coal surface roughness,the horizontal displacement in the excitation stage is smaller than the horizontal displacement in the stable stage,and the horizontal displacement of the working block increases again.As the absolute value of the displacement difference increases,the ultra-low friction effect is more significant;(4) The horizontal displacement amplitude and horizontal acceleration amplitude show a linear decreasing and then linear increasing law with the roughness of the coal surface;(5) The horizontal displacement abrupt change time and horizontal acceleration abrupt change time increase linearly with the roughness of coal surface,and then increase linearly.