Study On Mechanical Characteristics Of Coal Body Containing Gas Under Different Loading Rates

In this paper,the coal body in one level 1662(1)face of Pansan Coal Mine of Huainan is studied and analyzed.The effects of different loading rates on damage and micromechanics of coal body containing gas are analyzed by means of laboratory test,meso mechanical analysis and numerical simulation.Then the uniaxial compression test of coal body specimen with gas pressure of 2MPa under different loading rates is carried out.The influence of different loading rates on the mechanical characteristics of various stages of coal body containing gas is analyzed.The destruction process of coal body containing gas is divided into four stages.It is found that the loading rate has a significant influence on the peak strength,modulus of elasticity and failure mode of coal body containing gas,with the increase of loading rate,the peak strength and modulus of elasticity of gas bearing coal specimen shows a nonlinear decline trend and gradually tends to ease.The failure mode of specimen gradually changed from complete failure to local failure,when the loading rate is 0.2×10-3 mm/s,0.5×10-3 mm/s and 1×10-3 mm/s,the specimen shows complete failure state,the crack is through the whole coal body,the concrete manifestation is complete failure,two-way shear failure and unidirectional shear failure;when the loading rate is 2×10-3mm/s and 4×10-3,the specimen shows partial failure and the part of the coal remains intact,the concrete manifestation is the axis fracture failure and end failure.In order to better grasp the internal damage and destruction of coal containing gas,Acoustic emission monitoring test is carried out for the whole process of damage and failure to the coal body under different loading rates.It can be seen that the ringing count and energy reached the maximum value before the peak strength,indicating that the coal damage is the most serious.With the increase of loading rate,the number of acoustic emission ringing and the amplitude of energy increase gradually,and the accumulative ringing counts and accumulative energy of acoustic emission are also increasing gradually,it shows that the failure process of gas containing coal is fast and intense under high loading rate,and the specimen presents impact failure,and the damage increases sharply.The RFPA2D-Gasflow numerical analysis software was used to simulate the damage process of coal body containing gas in order to further verify the influence of the damage characteristics and acoustic emission characteristic parameters in the process of breaking of coal body containing gas.It is found that the numerical simulation results are in good agreement with the test results and the change trend of the acoustic emission characteristic parameters.It is of great significance to study the dynamic response of mining and destruction mechanism of coal body containing gas under different loading rates to recognize the nature of the coal mine motive force disaster.The acoustic emission testing technology is used to monitor the underground working face in real time and monitor the damage and destruction of the coal body containing gas according to the change of the characteristic parameters of the acoustic emission.The research can provide an important theoretical basis for the dynamic mining disaster prevention and effective prevention and control of deep and large space rapid mining and coal and gas outburst.It can effectively ensure the safe and efficient production of deep coal face.