不同含水率及围压条件下含瓦斯煤能量变化规律

Energy variation law behind coal containing gas under different water contents and confining pressures

为探究含瓦斯煤变形破坏过程中的能量耗散规律,利用自主研制的煤岩力学性质测试装置,开展含瓦斯煤在不同含水率及围压下的常规三轴试验,基于热力学第一定律,分析含瓦斯煤偏应力-应变曲线不同阶段和特征点处的能量变化规律。结果表明:不同含水率时,围压从12 MPa增大到20 MPa时,对应的弹性能占比增幅分别为60.33%、20.11%和3.86%,弹性能占比、破坏强度和弹性模量均增大,说明围压对含瓦斯煤体的变形破坏具有一定的抑制作用;不同围压时,含水率从1%增加到5%,对应的总能量分别下降25.38%、8.78%和6.23%,总能量、弹性能和破坏强度总体上均减小,导致含瓦斯煤更易破坏。含水率的增大使含瓦斯煤颗粒间摩擦力降低,促进煤颗粒间的相对移动。

This paper aims to explore the law of energy dissipation in the process of coal containing gas deformation and failure.The study consists of performing conventional triaxial tests on coal containing gas under different water contents and different confining pressures by using a self-developed testing device for the coal mechanical property;and analyzing the energy variation laws of deviatoric-strain curves at specified points and different stages based on the first law of thermodynamics.The results show that under different water contents,with the increase of the confining pressure from 12 MPa to 20 MPa,the corresponding elastic energy ratio increases by 60.33%,20.11%and 13.86%,respectively.The increase in elastic energy ratio,failure strength and elastic modulus indicates that confining pressure has an inhibition effect on the deformation and failure of coal containing gas.Under different confining pressures,with the increase of water contents from 1%to 5%,the corresponding total energy decreases by 25.38%,8.78%and 6.23%,respectively.The coal containing gas is easily broken caused by the decline of the total energy,elastic energy and failure strength.The friction between coal particles containing gas decreases with the increase of water content,which hastens the relative movement of coal particles.