三轴压缩下含瓦斯煤的能耗与渗流特性研究

以重庆松藻同华矿K3煤层制备的煤样为研究对象,利用自主研制的渗流装置,进行了不同围压和瓦斯压力下煤样的三轴压缩试验,并应用能量积聚与耗散的方法,研究了煤样在压缩过程中的能耗特征和渗流特性。结果表明:三轴压缩破坏过程中,含瓦斯煤样存在着能量积聚与耗散。煤样以弹性应变能的形式吸收并储存能量;荷载达到峰值时,煤样储存的弹性应变能在瞬间释放转化为耗散能,成为煤样破坏的源动力。围压和瓦斯压力对煤样的能耗特征有较大影响,随着围压增加,煤样吸收的总能量、储存的弹性应变能和耗散能均会增加;随着瓦斯压力增加,煤样吸收的总能量及耗散能呈现缓慢的增加,储存的弹性应变能呈逐渐下降趋势。围压和瓦斯压力对煤样的渗透性亦有较大影响。应力达到峰值前,随着围压的增加,煤样的渗透性逐步减小;随着瓦斯压力的增加,煤样的渗透性则呈增加的趋势。研究结果可为煤与瓦斯突出的防治和瓦斯抽采提供参考。

Research on characteristics of energy dissipation and seepage of coal containing gas under triaxial compression

This experiment takes the coal samples from coal seam K3 in Songzao Tonghua mine of Chongqing as an object. Triaxial compression tests under different confining pressures and gas pressures are conducted with a self-developed seepage device. In addition, the experiment studies the characteristics of energy dissipation and seepage of the coal samples during compression process with the method of energy accumulation and dissipation. The results show that the coal samples containing gas have the process of energy accumulation and dissipation during the failure of triaxial compression test. And the energy is absorbed and stored in the form of elastic strain energy within the coal samples. When the load reaches the peak, elastic strain energy stored in coal samples releases instantly into the dissipation energy, which becomes the driving force of coal sample damaging. There is a great influence of confining pressure and gas pressure on the dissipation characteristic of the coal. With the increasing of confining pressure, the total energy, the stored elastic strain energy and the dissipation energy of the coal sample would increase. With the increasing of gas pressure, the total energy and dissipation energy of the coal sample would slowly increase, while the stored elastic strain energy would gradually decrease. Confining pressure and gas pressure also have a great influence on the permeability of coal samples. Before the peak stress, the permeability of coal samples would decrease gradually with the increasing of confining pressure and would increases with the increasing of gas pressure. The study results can provide some references for prevention of coal and gas outburst as well as extraction of coal seam gas.