基于声发射上升时间/振幅与平均频率值的花岗岩劈裂破坏评价指标研究

通过花岗岩巴西劈裂试验，研究基于声发射RA（上升时间/振幅）与AF（平均频率）值的参数指标描述岩石破坏剧烈程度的可行性与优势。通过对比破坏过程中的RA与AF值分布的变化，与矩张量分析结果相互印证，发现即使宏观上以张拉为主的岩石劈裂破坏，在临近破坏阶段，仍会出现剪切破裂成分增加的现象，并提出了花岗岩巴西劈裂试验中基于RA与AF指标进行岩石破裂机制分析的判定建议值；提出r =RA/AF作为描述岩石破坏剧烈程度的基本指标，对比其与振幅参数在不同破坏阶段的变化趋势及不同传播距离下的衰减规律，结果表明：在衰减的影响下，基于r的参数指标将得到偏安全的评价结果；进一步提出r值变异系数CV(r)作为r值参数的统计指标，并与基于振幅的统计指标b值进行对比，对比结果验证了以CV(r)描述岩石破坏剧烈程度的可行性，且根据b值对岩石失稳破坏的判定值提出了花岗岩劈裂破坏中的CV(r)建议判定值。

Evaluation indexes of granite splitting failure based on RA and AF of AE parameters

Brazilian disk splitting tests were conducted on the granite disk specimens to study the feasibility of indexes based on AE parameters (i.e., RA and AF) for illustrating the fracturing intensity of rock failure. The distributions of RA and AF during the loading process were studied and compared with the results of SiGMA moment tensor analysis. The results show that the number of the shear cracks increases with approaching the damage stage even in the tensile failure of rock. The suggested judgement value for analyzing the failure mechanism based on RA and AF was proposed. An index r=RA/AF was proposed to illustrate the fracturing intensity of rock failure and was further compared with the amplitude parameter of distribution, variation and attenuation characteristics. The results show that the evaluation based on the index r leads to more conservative results. Furthermore, the coefficient of variation of r was proposed to be the statistical index of r and compared with b value, which is the statistical index of the amplitude. The results verified the feasibility of CV(r) in evaluating rock failure and the judgement value of granite splitting failure was suggested according to the b value.