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脆性岩石受载荷作用发生破裂的过程其能量释放具有临界性,为了更加清楚了解脆性岩石破坏过程及能量变化规律,对页岩进行单轴状态下的压缩试验,加载速率分别为0.01,0.1,0.5 mm/min。在加载过程中同步采集全过程声发射参数,计算绝对能量的概率密度函数并采用最大似然估计法计算表征概率密度函数的临界指数。结果表明:(1)每个加载速率下的能量概率密度函数在7个数量级范围符合幂定律分布。(2)最大似然估计得到的临界指数r具有一个最优的平坦稳定范围,能准确表征能量分布的幂定律。(3)子时间区间与全过程区间具有相同的临界指数r,因此可以通过试验前期的声发射情况了解破裂和破裂中能量释放的状态。
In order to understand the process of brittle rock destruction and energy variation more clearly, the compression tests of shale under uniaxial conditions were carried out at loading rates of 0.01, 0.1, 0.5 mm / min. During the loading process, the acoustic emission parameters of the whole process are collected synchronously, the probability density function of absolute energy is calculated, and the critical exponent of probability density function is calculated by maximum likelihood estimation. The results show that: (1) The energy probability density function under each loading rate conforms to the power law distribution over a range of seven orders of magnitude. (2) The critical exponent r obtained by maximum likelihood estimation has an optimal flat stability range and can accurately represent the power law of power distribution. (3) The sub-time interval has the same critical exponent r as the whole process interval. Therefore, the state of energy release in the rupture and rupture can be understood through the acoustic emission in the pre-test period.