突出过程中煤层及巷道多物理场参数动态响应

Dynamic response of coal seam and roadway during coal and gas outburst

  • 摘要: 为进一步认识煤与瓦斯突出发生机理及致灾机制,运用自主研发的多场耦合煤矿动力灾害大型物理模拟试验系统,针对中国重庆水江煤业(集团)有限责任公司水江煤矿K1煤层回采工作面的实际情况,开展了预定瓦斯压力2.0 MPa下的突出过程中的煤层及巷道内的动态响应试验研究。分析了突出过程中煤层内的瓦斯压力和温度,巷道内两相流的运动形态、冲击力和温度的变化规律。结果表明:突出过程中图像信息的灰度值变化能够反应煤与瓦斯突出过程中固相煤粉流的运动情况,固相煤粉在突出过程中存在振发特性及二次加速特征;煤粉的二次加速,意味着该处能量的集中,气相曳力增加;煤层瓦斯压力下降过程中存在“壅塞”现象,表现为瓦斯压力下降过程中的阶段性起伏,且该现象是突出振发特性的本质;地应力值越大,瓦斯压力和煤体温度的下降速度越快,且温度的变化与瓦斯压力的变化存在一致性,突出过程中煤体的温度下降量可达8 ℃;突出启动后,巷道内前期以弱扰动为主,距工作面5 044 mm才会出现较强的叠加扰动,随后,扰动呈现周期性升降,直至能量衰减至0;突出后期,虽然瓦斯膨胀能已不足以将煤体抛出孔洞,但是依然有大量瓦斯气体持续解吸,因此,突出的发展阶段还应包括后期的单相瓦斯气体的持续解吸和运移。

     

    Abstract: To further study the mechanism of coal and gas outburst and understand the process of dynamic disaster,the multi-field coupling testing system for dynamic disaster in coal mine was used. Based on the actual situation of the working-face of K1 coal seam in Shuijiang Coal Mine,Chongqing,China,the dynamic response test of coal seam and roadway during the outburst process with a predetermined gas pressure of 2. 0 MPa was carried out. The gas pressure and temperature of coal seam,the motion characteristics of two phase flow,the impact force and temperature of roadway during the outburst were investigated. The findings indicate that the change of the gray value of the image information in the outburst process can well reflect the kinematic characteristics of coal powder,and the pulverized coal has vibra- tion characteristics and secondary acceleration characteristics. The secondary acceleration of pulverized coal means that he energy is concentrated and the drag force is increased. There is a “ choking” phenomenon in the process of gas pressure drop in coal seams,which is represented by the periodic fluctuations of gas pressure,and this phenomenon is the essence of the vibration characteristics of outburst. The larger the geo-stress value,the faster the gas pressure and the temperature decrease, and the temperature change is consistent with the gas pressure change. During outburst process,the temperature drop of coal seam reaches 8 ℃ . After the outburst is triggered,the weak disturbance is mainly in the early stage of the roadway,and the superim-posed disturbance appears at 5 044 mm from the working plane. Then,the disturbance will periodically rise and fall until the energy decays to zero. In the later stage of outburst,al- though the gas expansion energy is not enough to throw the coal powder out of the cavern,there is still a large amount of gas desorbing continuously. Therefore,the development stage of outburst should also include the continuous desorp- tion and motion of the later single-phase gas.

     

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