单轴载荷下钻孔不同倾角试件能量演化特征

Energy evolution characteristics of specimens drilled at different inclination angles under uniaxial loading

为了研究煤层瓦斯抽采钻孔不同倾角对孔周煤体稳定性的影响,采用单轴压缩与声发射监测技术相结合的方式从能量转换角度分析了不同钻孔倾角下煤体裂隙的损伤特征;设计了5个不同钻孔倾角的型煤试验样品,利用电子万能试验机对试件进行单轴压缩试验,深入探究了不同倾角对煤体裂隙损伤特征的影响;借助声发射系统从能量转换的视角全面分析了试验过程中煤体裂隙的损伤演化特征。结果表明:随着钻孔倾角的增加含孔试件的单轴抗压强度、弹性模量呈减小趋势,而峰值应变呈线性增加趋势;AE环数与能量之间的变化关系与试件的失效过程密切相关,失效过程中AE事件的变化特征分为稳定发展阶段、高速发展阶段及完全发展阶段;声发射计数及能量随着钻孔倾角增加在减小,试件的整体承载力下降,AE峰值振铃数和峰值能量呈下降趋势,试件的极限储能值呈二次下降趋势。该研究可为瓦斯抽采钻孔稳定性的研究提供支持,对于推动煤炭行业向绿色、低碳转型具有重要的实践意义,有助于更好地实现双碳目标。

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 emission 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 conversion.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 specimen,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 emission 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.