To study the energy dissipation characteristics and damage evolution law of sandstone under cyclic loading, uniaxial cyclic loading tests are conducted on sandstone specimens under different frequencies with an MTS-815 rock testing machine. Furthermore, the characteristics of elastic modulus and energy evolution law during cyclic loading and unloading are explored. The results show that the loading and unloading moduli increase with the loading frequency. Under higher frequencies, the deformation resistance of the specimen is stronger, the elastic energy stored in a single cycle of loading is larger, the released energy is less, and it is less likely for the specimen to be damaged. At the beginning of loading, the energy dissipation ratio K decreases slowly with increasing loading cycles, and it then remains stable. When the specimen is close to failure, an inflection point of K appears, and K increases rapidly. Furthermore, the evolution equation of the damage variable is derived according to the strength characteristics and energy evolution law in the process of cyclic loading, and the reasons for the failure of sandstone specimens are explained from the perspectives of energy and fatigue damage.

中文翻译：

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不同循环加载频率下砂岩能量与疲劳损伤演化

为研究循环加载下砂岩的能量耗散特性和损伤演化规律，利用MTS-815岩石试验机对不同频率的砂岩试件进行单轴循环加载试验。进一步探讨了循环加载和卸载过程中的弹性模量特性和能量演化规律。结果表明，加载和卸载模量随着加载频率的增加而增加。在较高的频率下，试件的变形抗力更强，单次加载循环储存的弹性能量较大，释放的能量较少，试件损坏的可能性较小。加载开始时，耗能比K随着加载周期的增加而缓慢下降，然后保持稳定。当试件接近破坏时，出现K的拐点，K迅速增加。进而根据循环加载过程中的强度特性和能量演化规律推导出损伤变量的演化方程，从能量和疲劳损伤的角度解释砂岩试件失效的原因。