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利用RMT-150C型岩石力学多功能试验机,进行了盐岩单轴循环荷载作用下的疲劳试验,研究了盐岩的疲劳强度、变形及损伤特性。试验结果表明,当上限应力大于“门槛值”时,盐岩疲劳破坏时的轴向应变可以分为初始变形、等速变形和加速变形3个阶段,呈疏-密-疏的发展过程。改变上限应力和平均应力会显著影响疲劳的进程,提高上限应力值和平均应力值,初始轴向变形和循环轴向变形的比率都会提高,疲劳破坏时的总循环次数显著减小。盐岩疲劳破坏终点的变形量同样受静态轴向应力-应变全过程曲线的控制,控制误差范围在10%左右。循环荷载作用下,盐岩的变形模量经历了一个先逐渐增加,后缓慢降低,最后加速减小的过程。对循环荷载作用下盐岩疲劳损伤演化规律进行了初步探讨。
Using the RMT-150C rock mechanics multi-function testing machine, the fatigue test under salt rock uniaxial cyclic loading was carried out and the fatigue strength, deformation and damage characteristics of salt rock were studied. The experimental results show that when the upper limit stress is larger than “threshold value”, the axial strain of rock salt under fatigue failure can be divided into three stages of initial deformation, constant velocity deformation and accelerated deformation, which are sparse-dense-sparse development . Changes in the upper stress and the average stress will significantly affect the fatigue process, increasing the maximum stress and the average stress value, the initial axial deformation and axial deformation ratio will increase, the total number of cycles of fatigue failure significantly reduced. The deformation of rock salt at the end of fatigue failure is also controlled by the static axial stress-strain curve, and the control error range is about 10%. Under cyclic loading, the deformation modulus of salt rock underwent a process of first increasing gradually, then slowly decreasing, and finally accelerating and decreasing. The evolution of fatigue damage of salt rock under cyclic loading was preliminarily discussed.