Energy evolution characteristics of specimens drilled at different inclination angles under uniaxial loading
To study the influence of different inclination angles of coal seam gas extraction boreholes on the stability of the coal body around the boreholes,the uniaxial compression combined with acoustic e-mission monitoring technology was used to analyze the damage characteristics of the coal body fissures under different borehole inclination angles from the perspective of energy conversion.Five coal test samples with different drilling inclination angles were designed,and the uniaxial compression test was carried out on the specimens by using an electronic universal testing machine,so as to investigate the influence of different inclination angles on the damage characteristics of the coal body fissures.At the same time,with the help of acoustic emission system,a comprehensive analysis was made of the damage evolution characteristics of the coal body fissures during the test from the perspective of energy conver-sion.The results show that the uniaxial compressive strength and modulus of elasticity of the specimens decrease with the increase of drilling inclination,and the peak strain increases linearly.The changing relationship between AE ring counts and energy is related closely to the failure process of the speci-men,and the changing characteristics of AE events during the failure process are divided into stable development stage,high speed development stage and complete development stage;the acoustic emis-sion counts and energy are decreasing with the increase of drilling inclination angle,the overall bearing capacity of the specimen is decreasing,the AE peak ring counts and the peak energy show a decreasing trend,and the limiting energy storage value of the specimen is in the trend of a quadratic decrease.The results could provide support for the study of the stability of gas extraction boreholes,which is of great practical significance for promoting the transition of the coal industry to green and low-carbon,and helps to better realize the dual-carbon goal.
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