基于三轴加卸载试验的花岗岩弹性模量变异与能量演化分析

Analysis of Elastic Modulus Variation and Energy Evolution of Granite Based on Triaxial Loading and Unloading Test

为了研究岩体的变形特征和能量特征与其所处应力状态之间的关系,开展了5种围压下花岗岩的三轴循环加卸载试验.基于应力-应变曲线,计算了循环加卸载过程中花岗岩的弹性模量和能量密度,分析了应力状态对弹性模量及能量演化规律的影响.研究结果表明:轴向弹性模量随围压的增大而增大,随轴向应力的增大先增大后减小.轴向弹性模量与最大、最小主应力呈现良好的二次函数关系.随着围压的增大,能量密度与弹性能占比(弹性能与输入总能量之比)均显著增大,岩石储能能力提高;随着轴向应力增大,弹性能占比先增大后减小.弹性能占比减小阶段即岩石损伤加剧阶段,围压的增加延长了岩石的损伤演化过程.最后讨论了应力状态、岩石力学参数及能量状态的关联性.

To investigate the relationship between the deformation and energy characteristics of the rock mass and the stress state,triaxial cyclic loading and unloading tests on granite under five types of confining pressure were carried out.Based on the stress-strain curves,the elastic modulus and energy density of the granite were calculated during cyclic loading and unloading,and the influence of the stress state on the evolution of the elastic modulus and energy was analyzed.The results show that the axial modulus of elasticity increases with the increase of the confining pressure,and increases first and then decreases with the increase of the axial stress.The axial modulus of elasticity shows a good quadratic function with the maximum and minimum principal stresses.The energy density and the proportion of elastic energy(the ratio of elastic energy to total energy input)increase significantly as the confining pressure increases,and the energy storage capacity of the rock increases.The proportion of elastic energy increases first and then decreases as the axial stress increases.The decrease in the proportion of elastic energy is the stage of increased damage to the rock,and the increase in the confining pressure prolongs the process of damage evolution.Finally,the correlation between stress state,rock mechanical parameters,and energy state is discussed.