三轴压缩条件下煤岩力学特性及破坏模式

摘要

为探究三轴应力环境下某矿区煤样的力学特性及破坏模式,设置围压梯度为0.2、0.4、0.8、1.1、2.0、3.0 MPa,采用电-液伺服试验系统开展室内三轴试验;对试验数据拟合分析,建立峰值抗压强度、弹性模量与围压关系表达式;对煤样破坏特征分析,讨论施加围压大小对煤样试件不同破坏模式的影响程度.结果表明:峰值抗压强度和弹性模量随围压增大呈递增趋势;且峰值抗压强度和弹性模量的增幅随围压增大呈现出先增大后减小的变化规律;峰值抗压强度与围压呈对数函数分布规律;而弹性模量随围压增大呈指数函数形式递增.随着围压增大,煤样破坏形式可能表现为拉伸-拉剪(拉伸主导)-拉剪(剪切主导)-剪切的破坏模式.%In order to investigate the mechanical properties and failure modes of coal samples from a coal mine under triaxial compression environment,setting up confining pressure gradient of 0.2,0.4,0.8,1.1,2.0 and 3.0 MPa,the electro-hydraulic servo testing system is used to carry out the triaxial test;fitting analysis for test data,the expression about relationship of peak compressive strength,elastic modulus and confining pressure is established;failure characteristics of coal samples are analyzed,the impact of applying confining pressure on coal samples with different failure modes is discussed.The results show that:the peak compressive strength and elastic modulus increase with the confining pressure,and the variation of peak compressive strength and elastic modulus increases first and then decreases with the increasing of confining pressure;the peak strength and confining pressure present a logarithmic distribution law;while the elastic modulus increases exponentially with the increase of confining pressure;with the increase of confining pressure,the failure modes of coal samples may be the tensile-shear (tensile dominated)-shear failure mode.