三轴压缩条件下千枚岩破裂与能量特征研究

摘要

利用MTS815程控伺服岩石力学试验系统,对千枚岩进行不同围压下的三轴压缩试验,研究围压对千枚岩变形破坏特征和能量演化特征的影响.结果表明:在低围压下,千枚岩破坏模式为张-剪复合型破坏,随着围压升高,破坏模式转变为剪切破坏;弹性应变能曲线和耗散能曲线的交点k为能量分界点,k之前表现为能量积聚,k之后表现为能量释放;总能量与轴向应变关系曲线在加载初期呈下凹曲线,能量增速升高,加载后期呈上凸曲线,能量增速降低;特征应力点的总能量和储能的弹性应变能均随围压的增大而增大;围压对岩石内部裂纹扩展和峰后能量释放均有阻碍作用.%In order to study the influence of confining pressure to deformation and failure characteristics and energy evolution characteristics of phyllite,the conventional triaxial compression test is carried out with MTS815 servocontrolled rock mechanical test system.The results show the follows.As the confining pressure increases,the failure mode of phyllite changes from shear failure to mixed tensile-shear failure.The point k is the intersection of the curve of elastic strain energy and the curve of dissipation,before the k point of energy accumulation and after the k point of energy dissipation,respectively.In the early stage of loading,the curve of total energy and axial strain is concave curve,where the energy growth rate is to rise.In the later stage of loading,the curve of total energy and axial strain is convex curve,where the growth rate of energy reduces.At the point of peak strength,the total energy and energy storage limit has a linear relationship with the confining pressure.Confining pressure can hinder the crack propagation and energy release.