岩石在不同应力幅值下受低频循环扰动的力学特性试验

设计3种不同类型的岩石在不同应力幅值下的循环扰动试验。试验结果表明:当扰动应力幅值较小时,岩石在循环加载下出现弹性模量强化效应,不同类型的岩石弹性模量强化程度不同;循环动力扰动加载试验存在应力上限门槛值,只有大于应力上限门槛值,试样才会发生破坏;扰动应力幅值对岩石的破坏影响显著,在高应力幅值下,循环次数迅速减少;在低应力幅值下,试件破坏形态为剪切破坏,在高应力幅值下,破坏形态复杂,出现板裂化破坏和碎块弹射。建立了循环扰动作用下的应变损伤模型,通过分析不同应力幅值下损伤变量的变化规律,得出如下结论:岩石损伤可划分为迅速增长阶段、平稳发展阶段、快速增大阶段,且随着扰动应力幅值的增加,平稳发展阶段的循环数显著减少;当应力幅值提高,损伤变量变化率显著提高,应变迅速增加,岩石破坏。

Rock mechanical properties experiments with low-frequency circulation disturbance under different stress amplitudes

The rock mechanics experiments were designed under different stress amplitudes.The results showed that the elastic modulus reinforcement effect was appeared when the disturbance stress amplitude was small.The rock samples were damaged only when the stress was greater than stress limit threshold value.The disturbance stress amplitude level influenced the destruction of rock significantly.The cycle numbers were reduced rapidly under the high stress amplitude.The specimens’ failure pattern was shear failure when the stress amplitude was low and the failure pattern was complex when the stress amplitude was high.The strain damage model was established under circulation disturbance.By analyzing the change law of damage variable under different stress amplitudes,the rock damage can be divided into a rapid growth stage and stable stage of development and rapid increase stage.The cycle number of development stage was reduced development with the increase of stress amplitude disturbance.The damage variable rate increased significantly and the strain of rock increased rapidly with the increase of stress amplitude disturbance.