中文摘要：

利用MTS 810动力试验机,开展0.5,1.0,1.5,2.0,2.5,3.0 Hz加载频率下石灰岩低周疲劳试验研究,以探索不同加载频率对岩石疲劳寿命和变形特性的影响。试验结果表明,石灰岩疲劳寿命与加载频率间满足双对数坐标系下的线性关系,疲劳寿命随加载频率的增加而增加。其主要原因在于石灰岩有较强的率敏感性,压缩强度随加载速率的提高而提高。石灰岩轴向变形发展具有明显的三阶段演化规律,且变形发展二、三阶段累积变形量几乎不受加载频率影响,均基本保持稳定。在所加载的频率范围内,疲劳破坏极限变形受控于单向压缩全应力–应变关系曲线,破坏点和控制点应变之间的相对误差与加载频率无关。不同频率下的试验结果表明了岩石疲劳破坏时的极限变形规律不受加载频率影响的普遍规律。变形发展第二阶段的每个循环平均应变增量随加载频率的提高而降低。结合石灰岩疲劳变形演化规律,提出基于平均应变增量的疲劳寿命计算模型。该模型预测结果偏于保守,且模型参数容易取得。

英文摘要：

For searching the impact of loading frequency on the fatigue life and deformation characteristics of rock,low cyclic fatigue tests of limestone were conducted under 0.5,1.0,1.5,2.0,2.5 and 3.0 Hz loading frequencies by using a MTS 810 dynamic test system. The results indicate that there are well linear relationship between fatigue life and loading frequency in double logarithmic coordinate and fatigue life increases with the raises of frequency. It is mainly due to the strong sensitivity of limestone for loading rate and uniaxial compress strength of limestone increasing with the improvement of loading rate. The axial deformation of limestone goes through three-stage evolution. The cumulative amount of deformation in the second and third evolution stages is almost independent of loading frequency. In the range of loading frequencies,the ultimate deformation of limestone samples in fatigue tests is controlled by uniaxial compressive stress-strain curve,the calculated relative error is nothing to do with loading frequency. The tests results under different frequencies indicate that ultimate deformation law of rock fatigue failure which is hardly impacted by load frequency is a universal law. The average strain increment of each cycle in the second evolution stage reduces with the increase of loading frequency. Combined with the law of limestone deformation evolution,a strain-increment-based fatigue life calculated model was proposed. The evaluation results of this model are more conservation than measured ones,and its parameters are easy to obtain.