岩石在高应力状态下受循环动力扰动作用的力学性能是影响深部岩体工程长期稳定性的重要因素。在MTS-322电液伺服试验机上,分别改变平均应力和循环应力幅值对深部大理岩试样进行高应力下的单轴小幅循环动力扰动试验。结果表明:循环动力扰动的上限应力小于一定值时,动力扰动对岩石抵抗变形的能力起强化作用;随着平均应力的提高,每次循环动力扰动周期内岩石的变形量增大、岩石破坏的动力扰动数则呈指数减少;当上限应力与岩石静力强度相近时,平均应力和循环应力幅值的改变对岩石的疲劳寿命具有明显影响,它们与破坏时的循环数之间呈负指数关系;随着循环数的增加,不可逆变形和损伤变量均呈现先快速增大、然后低速增加和最后高速增长直至岩石破坏的变化规律,变形模量则呈先急剧增大、然后缓慢减小至最后急剧减小的变化规律,不同应力幅值对岩石损伤的发展速率和发展阶段具有明显影响;静力和循环动力扰动共同作用条件下,大理岩的破坏表现出剪切和张拉疲劳2种特征。
The rock's mechanical property when it is loaded with high static stress and cyclic dynamic disturbances is a key factor influencing the stability of deep rock engineering. Mechanical experiments of marble collected in a deep mine under high stress and circle dynamic disturbance of small amplitude were carried out on the electro-hydraulic servo testing system MTS-322, by changing average stress and amplitude of cyclic dynamic disturbance, respectively. The results show that dynamic disturbance will enhance the ability of rock to resist deformation unless the maximal stress of cyclic dynamic disturbance reaches a certain value; during a period of cyclic dynamic disturbance, the deformation of rock increases with the average stress, and the number of cyclic dynamic disturbance when rock failures has a negative exponential relation with the average stress; when the maximal stress is near the static strength of rock, the average stress and amplitude of cyclic dynamic disturbance influence obviously the fatigue life of rock, which have a negative exponential relation with the number of cyclic dynamic disturbance; with the increase of the number of cyclic dynamic disturbance, the irreversible deformation and damage go through a process of increasing sharply, increasing slightly and increasing sharply, and corresponding with this, the deformation modulus increasing sharply, decreasing slightly and decreasing sharply,and change of amplitude influences significantly the velocity and stage of development of damage, and failure of marble under static and cyclic dynamic disturbance has characteristics of shear failure and tensional fatigue failure.