循环荷载下岩石损伤的CT细观试验研究

STUDY OF CT MESO-EXPERIMENT OF ROCK DAMAGE UNDER CYCLIC LOAD

利用CT机专用加载试验设备,进行实时的两级循环荷载作用下岩石疲劳损伤演化CT细观试验,得到岩石细观疲劳损伤扩展的初步规律。研究表明:一级循环荷载为强度的38%～76%时,随着循环次数的增加,上限应力处全区CT数标准差有增加的趋势,密度和CT数有减小的趋势,但变化很小,说明这一过程损伤的积累是缓慢的;二级循环荷载为强度的45%～90%时,虽然试验时循环次数少于一级循环荷载,但上限应力处全区CT数标准差、密度和CT数变化要大于一级循环荷载;在岩石破坏前的1个循环,CT数标准差、密度和CT数有较大变化。

The computerized tomography（CT） real-time tests of fatigue damage meso-propagation law of rock under two-grade cyclic loads have been accomplished using specified loading equipment of CT machine. It is shown that in the first grade of cyclic load equal to the strength of 38% to 76%, the standard deviation of CT number under the maximum stress increases with the increase of the number of cycle; while the density and CT number tend to decrease with relatively small variations. The process shows that the accumulation of damage is slow. In the second grade of cycle load equal to the strength of 45% to 90%, although the number of cycle is less than that in the first grade, the changes of standard deviation of CT number under the maximum stress, density and CT number are larger than those in the first grade; in the cycle before failure, the standard deviations of CT number, density and CT number change greatly.