用低周疲劳加载实现中等应变速率下岩石动态破坏的新方法

A New Test Method to Achieve the Dynamical Rock Failure with Medium Strain Rate by Low-cycle-index Fatigue Loading

采用低周疲劳加载方法在Instron电液伺服控制材料试验机上实现了岩石中等应变速率下的动态加载破坏试验。为研究岩石在中等应变速率下的动态加载或动静组合加载的破坏特性及本构关系提供了一种可行的试验方法。试验结果表明:随着加荷频率的增加,岩石试件的平均应变速率也增加,当加荷频率大于0.5Hz时,平均应变速率就可以稳定地达到10-2s-1;在保持加荷频率不变的情况下,在岩石材料的弹性变形范围内改变预静载的大小,对岩石试件的平均应变率的影响不大,可以近似地认为加荷频率相同,应变速率也相同。

By using of the INSTRON electro-hydraulic and servo-controlled material testing machine and adopting low-cycle-index fatigue loading method, the test of rock failure with medium strain rate under dynamical loading had been carried out successfully. This provides a feasible testing method for studying the behavior and constitutive relation of rock failure with medium stain rate under dynamical loading or static and dynamical combination loading. The test results have shown that the average strain rate of test rock specimen increases with the increasing of loading frequency, the strain rate can reach a stable value of 10-2 S-1 as the loading frequency is higher than 0.5 Hz, in the case of uniform loading frequency, within the range of rock elasticity the change of value of static preload has less influence on the average strain rate of test rock specimen, therefore, it could approximately be considered that the same loading frequency will result in the same strain rate.