To study the fracture characteristics and fatigue damage of fractured rock masses, noncoplanar fractured rocklike specimens prepared using cement mortar were used for a graded cyclic loading–unloading test. The results showed that the two ends of the horizontal crack were the main stress concentration areas, and they inhibited crack initiation of the inclined fracture. With increasing crack inclination, the inhibitory effect became more obvious. Under the condition that the lower limit stress is constant, as the upper limit stress increases, energy dissipation of the specimen increases, becoming relatively stable in each stage of the cycle. With increasing crack inclination, the increase in the energy dissipation value decreases. Specimens with large changes in the shape of their hysteresis loop tend to exhibit large fluctuations in the elastic modulus. As the loading progressed, the elastic modulus exhibited a downward trend, and the damping ratio tended to be stable. The change in the damping ratio is affected by the dynamic elastic modulus and area of the hysteresis loop. Based on the Weibull probability distribution function, the evolution curve of the damage variable of the specimen can be obtained. This curve reflects the trend of the damage change of the rocklike specimens under various levels of cyclic loading and unloading.

中文翻译：

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单轴梯度循环加载与卸载下非共面裂缝性岩石样的断裂特征和疲劳损伤

为了研究裂隙岩体的断裂特性和疲劳损伤，使用水泥砂浆制备的非共面裂隙岩样标本用于分级循环加卸载试验。结果表明，水平裂纹的两端是应力集中的主要区域，它们抑制了倾斜裂缝的裂纹萌生。随着裂纹倾角的增加，抑制作用变得更加明显。在下限应力恒定的条件下，随着上限应力的增加，样品的能量耗散增加，在循环的每个阶段变得相对稳定。随着裂纹倾角的增加，能量耗散值的增加减小。磁滞回线形状发生较大变化的试样往往会表现出较大的弹性模量波动。随着载荷的进行，弹性模量呈现下降趋势，并且阻尼比趋于稳定。阻尼比的变化受动态弹性模量和磁滞回线面积的影响。基于威布尔概率分布函数，可以获得标本损伤变量的演化曲线。该曲线反映了在不同水平的循环加载和卸载条件下岩样的损伤变化趋势。基于威布尔概率分布函数，可以获得标本损伤变量的演化曲线。该曲线反映了在不同水平的循环加载和卸载条件下岩样的损伤变化趋势。基于威布尔概率分布函数，可以获得标本损伤变量的演化曲线。该曲线反映了在不同水平的循环加载和卸载条件下岩样的损伤变化趋势。