为深入探究深部开挖过程中岩体卸荷致灾过程的内部响应特征及其灾变规律,利用自主研发的三轴声发射采集系统,对砂岩进行不同围压、不同卸荷速率下的常规三轴卸围压声发射试验,并采用地震统计学方法对声发射绝对能量E,等候时间δ等参数进行统计分析。结果表明:(1)卸荷过程释放绝对能量的概率密度函数在10~1～10~4aJ 4个能级内服从幂律分布;(2)随着卸载速率减小,出现在小能量区间的声发射事件可能性增大,相同卸压速率下随着围压的增大也会出现类似的变化趋势;(3)声发射“余震”事件在不同围压和卸荷速率下遵循同一线性关系,且不受“主震”事件能量大小波动的影响;(4)在小等候时间区间内(<0. 1 s),幂指数不受围压和卸载速率的影响,对于大等候时间区间(> 0. 1 s),幂指数在1. 3到1. 9区间波动,并且不同能量阈值下的等候时间分布具有一致性。

In order to thoroughly explore the internal response characteristics and the catastrophic behaviors of rock mass caused by unloading in deep excavation process,the self-developed triaxial acoustic emission acquisition system is used to conduct the triaxial unloading tests of sandstone with different unloading rates and different confining pres-sures. Seismic statistics method is used to analyze the parameters such as absolute energy E and waiting time δ. The re-sults show that:① the probability density function of absolute energy released in the unloading follows a power law dis-tribution well in the range of 101 aJ to 104 aJ. ② With the decrease of unloading rate,the possibility of small energy events occurrence is increasing. There is a similar trend with the increase of confining pressure in the same unloading rate. ③ The “ after-shock” of acoustic emission events meets the same linear relationship under different confining pressures and unloading rates,and it is not affected by the fluctuation of the “ main shock” events energies. ④ In a short time interval range (less than 0. 1 s),the power exponent is not affected by confining pressure and unloading rate. For a long interval range (greater than 0. 1 s),the power exponent fluctuates in the range of 1. 3 to 1. 9. The dis-tributions of waiting time for different energy thresholds show universality well.