华山花岗岩力学特性及能量演化规律研究

为了研究华山花岗岩的强度、变形特征以及能量耗散规律, 采用MTS815岩石力学试验机开展了单轴压缩和常规三轴压缩试验。结果表明:华山花岗岩表现出明显的脆性特征, 在三轴条件下应力应变曲线的上凹现象相比于单轴变得不明显; 随着围压的增加, 花岗岩的弹性模量和峰值应变不断增大, 但增加的速度逐渐变慢; 花岗岩的扩容阈值与围压近似呈线性关系; 单轴压缩条件下, 岩石内部储存的弹性应变能峰值后几乎瞬间都转化为耗散能, 劈裂破坏特征明显, 而三轴压缩下, 岩样的耗散能占吸收能的比例随围压提高逐渐增大, 表现为整体剪切破坏; 三轴压缩下的吸收能、弹性应变能以及耗散能都远大于单轴压缩下的对应值, 并且随着围压的增大而增大; 岩石破坏时的吸收能、耗散能以及储能极限均与围压存在良好的线性关系。

Study on mechanical property and energy evolution law of Huashan granite

To explore the strength, deformation and energy dissipation characteristics of Huashan granite, uniaxial and triaxial compression tests were carried out using MTS 815 test system.The results show that the granite has obvious brittle characteristics.The "concave-upward" phenomenon of stress-strain curves from triaxial compression tests is less obvious than those from uniaxial compression tests.The elastic modulus and the strain corresponding to the peak stress increase with the increase of confining pressure, but the rate of increase gradually slows down.There is a linear relationship between the dilatancy threshold of the granite and the confining pressure.Under uniaxial compression, the elastic strain energy of the rock sample is mostly transformed into dissipated energy once the peak stress is reached, demonstrating evident splitting failure.As for the triaxial compression of the rock samples, the ratio of dissipated energy to absorbed energy increases with the increase of confining pressure, accompanied by a general shear failure.The absorbed energy, the elastic strain energy and the dissipated energy under triaxial compression are much higher than those under uniaxial compression, and they all increase as the confining pressure increases.Additionally, there is a linear relationship between the confining pressure and the absorbed energy, the dissipated energy and the energy storage limit.