大理岩卸荷破坏变形及能量特征研究

STUDY OF DEFORMATION AND ENERGY PROPERTIES OF MARBLE UNLOADING FAILURE

对大理岩试样进行恒轴压条件下峰前、峰后卸围压破坏试验,研究岩石的变形破坏特征及破坏过程能量演化规律,得到以下结论:恒轴压条件下环向变形随卸荷速率增大而减小,而轴向变形变化很小,轴向变形没有明显的速率变化效应;峰前、峰后卸荷都为典型的剪切破坏,而峰后卸荷有明显的共轭剪切带;卸荷破坏过程能量转化大致分为能量积聚、能量耗散和能量释放3个阶段;卸荷速率越快,弹性应变能释放得越快、越剧烈;耗散能变化率随卸荷速率的增加也变大;耗散能变化率比弹性应变能变化率大一个数量级,能量快速耗散是大理岩卸荷破坏过程的主要特征。

Pre-peak and post-peak strength unloading failure experiments on marble under constant axial pressure were conducted. The characteristics of deformation and energy evolution during the process of marble failure were studied. Results show that the lateral deformation decreases with the increase of unloading rate. The axial deformation is relatively small. It has no relation with unloading rates under the condition of constant axial pressure. The failure mode is typical shear failure under the pre-peak or post-peak strength unloading. Unloading after the peak strength leads to obviously conjugate shear zone. Marble unloading failure process can be divided into three stages according to energy evolution:energy accumulation stage,energy dissipation stage and energy release stage. The faster the unloading rate,the more quickly and more intensely the elastic strain energy releases. The change rate of dissipated energy goes up with the unloading rate increase. And it is ten times larger than the rate of elastic strain energy. Dissipation energy plays a dominant role in the rock's failure process. The rapid energy dissipation is the main feature of marble unloading failure.