Study On Seepage Characteristics And Energy Consumption Characteristics Ot、Tectonic Coallnfluenced By Mining Activities

Under the action of deep ground stress and gas pressure,the formation of soft coal has high gas content,active energy migration,and potential threat of coal and gas outburst.It is a difficult point to study coal and gas outburst.The practice of mining engineering shows that the deep coal rock mass is in a three-dimensional stress equilibrium state before mining,and the coal body undergoes confining pressure unloading and axial compressioncycleloadingandunloadingduringthemining process.Therefore,it has very important value and practical significance in studying the seepage characteristics and energy consumption characteristics of tectonic coal under the influence of mining stress for the gas drainage and utilization of deep structural soft coal,the improvement of coal seam gas permeability and the prevention of coal and gas outburst.Based on the above understanding,this paper takes the structural coal of 18506 working face in the 8^#coal seam of Malan Mine as the research object,using WYS-800 electro-hydraulic servo three-axis gas flow seepage device to carry out conventional triaxial compression and mining unloading.The seepage test of gas-containing structural coal with pressure and axial cyclic loading and unloading,combined with the principle of energy consumption,analyzes the energy consumption characteristics during the seepage process of coal body,and draws the following main conclusions:Under uniaxial compression,the strength and elastic modulus of coal body decrease with the increase of loading rate;the larger the uniaxial loading rate,the more energy released when the coal body reaches the failure,the more easily the coal body is destroyed.Under the condition of fixed confining pressure,with the increase of gas pressure,the permeability of coal body decreases with a negative exponential function,but the change of permeability is gradually weakened by the influence of gas pressure;with the increase of gas pressure,the peak value of stress is reached.When the total energy absorbed by the coal body is reduced,the elastic strain energy is reduced,and the coal body dissipation energy is increased.Under the condition of fixed gas pressure,the coal permeability decreases linearly with the increase of confining pressure.The total energy absorbed,the stored elastic energy and the released dissipative energy increase when reaching the peak point;the coal body absorption before yielding The energy is mainly converted into elastic energy,and the permeability is gradually reduced.In the yielding and failure stages,the elastic energy is released into a dissipative energy in a large amount,and the coal permeability continues to increase.Under the condition of unloading confining pressure,the larger the initial unloading confining pressure,the more energy is needed when the coal body is destroyed,but the energy required for the coal body to reach the peak point under the unloading confining pressure is less than the conventional triaxial compression.The relationship between coal damage and permeability evolution based on dissipative energy can be roughly divided into three stages:before the unloading confining pressure,the coal body damage increases slowly,and the permeability decreases with the increase of damage as a logarithmic function;In the unloading confining pressure stage,the coal body damage increases rapidly;after the coal body is destroyed,the damage increase rate is faster;after the unloading confining pressure,the permeability increases exponentially with the increase of the damage.Under the condition of axial grading cycle loading and unloading,the?₁-?₁ curve shows a spiral rise,the permeability shows a spiral drop,and the permeability-strain curve crosses at a lower confining pressure.As the number of loading and unloading increases,the absolute recovery rate of permeability decreases;with the increase of the upper limit stress of the grading loading and unloading,the total energy,elastic energy and dissipative energy absorbed by the coal during the loading and unloading process increase with the increase of the number of cycles,and the damage variable of the coal body also increases,but the rate of increase is slower;from the cycle of loading and unloading to the yield point of coal,the permeability decreases logarithmically with the increase of damage until the lowest point of permeability is reached;in the stage of yield to coal destruction,the rate of increase of coal damage variable becomes faster,and the permeability increases.As the damage increases,the exponential function increases and the coal body accelerates to destroy.