不同瓦斯压力原煤全应力应变过程中渗透特性研究

煤炭地下开采过程中,常会遇到不同瓦斯赋存压力和三维受力状态等复杂条件下的煤岩体瓦斯渗透问题，为系统探究其瓦斯渗透规律，利用改进的MTS815 Flex Test GT岩石力学试验系统，开展了原煤三轴压缩全过程渗透试验，对不同瓦斯压力原煤三轴压缩全过程中渗透特性进行了探讨，分析了煤岩变形破坏过程中其瓦斯渗透特性，以及不同瓦斯压力下煤岩的瓦斯渗透特性。结果表明：煤岩瓦斯渗透率-应变曲线与煤岩三轴压缩全应力-应变曲线具有很好的对应关系，其瓦斯渗透率随加载变形破坏呈先减小后增大趋势，在峰前70%~85%应力水平时达到最小值，煤岩瓦斯渗透率在应力峰值附近时均有不同程度的急剧上升；另一方面，煤岩瓦斯渗透率和瓦斯流量随瓦斯压力的升高呈先增加后减小的趋势，瓦斯压力为1 MPa时达到最大值，在1~3 MPa时，煤岩具有较好的渗透能力，针对现场实际情况，通过类似分析，设定合理的抽采负压区间，从而保证煤与瓦斯共采安全高效进行。

Research on permeability characteristics of raw coal in complete stress-strain process under different gas pressure

During the coal mining,the gas permeation of coal is a phenomenon often encountered in the complex condition of different gas occurrence pressures and three-dimensional stress state.In order to investigate the permeability characteristics of coal under above condition,A triaxial seepage test of raw coal samples was carried out using the improved MTS815 Flex Test GT system,the permeability characteristics of raw coal sampleswere discussedunder triaxial compression and different gas pressures,the permeability characteristics of raw coal were analyzed during the deformation and failure,and the gas seepage under different gas pressures was also analyzed for raw coal samples.The results show that the permeability-strain curve of raw coal is in accord with the complete stress-strain curve in the process of triaxial compression.The gas permeability decreasesinitially and then increases during the loading process,reaching the minimum at the 70%-85% stress level before the stress peak.The gas permeability rapidly increases at different extents when it is near the stress peak.On the other hand,as gas pressure increasesgradually,the permeability and gas flow increase first and then decrease,reaching the maximum at the gas pressure of 1 MPa.Coal samples have a better penetration ability when gas pressure is in the range of 1-3 MPa.According to the practical situation,the range of the suction pressure of gas drainage should properly be set by similar analysis,so that thesimultaneous extraction of coal and gascan be conducted safely and efficiently.