渗透水压力作用下灰岩单轴疲劳特性试验研究

Experimental Study on Uniaxial Fatigue Characteristics of Limestone Under Seepage Pressure

为探究不同渗透水压力条件下的灰岩循环荷载疲劳特性,采用高渗透-应力耦合试验系统对18组灰岩岩样进行了不同渗透水压条件下1 Hz循环频率加卸载疲劳试验。结果表明:渗透水压力对灰岩的疲劳破坏演化过程各阶段均有不同程度影响;在初始疲劳阶段,随着渗透水压力的增大,灰岩的不可逆变形增长速率提高,但其持续周期明显降低,在不同渗透水压力作用下,灰岩的变形增长速率随循环次数增加而减小;在稳定疲劳变形阶段,灰岩不可逆积累变形速率呈小幅提高,岩样进入加速疲劳阶段的循环周次降低;在加速疲劳变形阶段,灰岩破坏演化过程由突发增长逐渐向稳定增长过度,加速破坏阶段与稳定疲劳阶段分界点逐渐消失。

To explore the cyclic loading fatigue characteristics of limestone under different seepage pressures,a high permeability-stress coupling test system was used to carry out loading and unloading fatigue tests on 18 groups of limestone samples under different seepage pressures at 1 Hz cyclic frequency.The results show that the seepage pressure has varying degrees of influence on each stage of the fatigue failure evolution process of limestone.In the initial fatigue stage,the irreversible deformation growth rate of limestone increases as the seepage pressure increases,but its duration is significantly reduced.The deformation growth rate of limestone decreases as the number of cycles increases under different seepage pressures.In the stable stage of fatigue deformation,the irreversible accumulation deformation rate of limestone increases slightly,and the cycle times of the limestone sample entering the accelerated fatigue stage decreases.In the accelerated stage of fatigue deformation,the failure evolution process of limestone gradually changes from the sudden growth to steady growth,and the boundary point between the accelerated failure stage and the stable fatigue stage gradually disappears.