Du Kun, Yang Songge, Zhou Jian, Wang Lichang
School of Resources and Safety Engineering, Central South University, Changsha 410083, China.
School of Geosciences and Info-Physics, Central South University, Changsha 410083, China.
Materials (Basel). 2023 Apr 14;16(8):3101. doi: 10.3390/ma16083101.
Rockburst is one of the common geological hazards. It is of great significance to study the evaluation indexes and classification criteria of the bursting liability of hard rocks, which is important for the prediction and prevention of rockbursts in hard rocks. In this study, the evaluation of the rockburst tendency was conducted using two indoor non-energy indexes, namely the brittleness indicator (2) and the strength decrease rate (). The measuring methods of and as well as the classification criteria were analyzed. Firstly, the most rational calculation formulas for and were selected based on previous studies. The 2 equaled to the ratio between the difference and sum of uniaxial compressive strength and Brazilian tensile strength of rocks. The was the average stress decrease rate of the post-peak stage in uniaxial compression tests and equaled the uniaxial compressive strength dividing the duration time of post-peak rock failure in uniaxial compression tests. Secondly, the uniaxial compression tests of different rock types were designed and carried out, and the change trend of B and with the increase of loading rate in uniaxial compression tests were studied in detail. The results showed that after the loading rate was greater than 5 mm/min or 100 kN/min, the value was affected, limited by the loading rate, while the value was more affected by the strain rate. The displacement control, with a loading rate of 0.1-0.7 mm/min, was recommended for the measurement of and . The classification criteria of 2 and were proposed, and four grades of rockburst tendency were defined for and 2 according to the test results.
岩爆是常见的地质灾害之一。研究硬岩岩爆倾向性的评价指标和分类标准具有重要意义，这对硬岩岩爆的预测和防治至关重要。本研究采用两个室内非能量指标，即脆性指标（2）和强度降低率（）对岩爆倾向性进行评价。分析了和的测量方法以及分类标准。首先，根据以往研究选取了最合理的和的计算公式。2等于岩石单轴抗压强度与巴西劈裂抗拉强度之差与和的比值。是单轴压缩试验峰后阶段的平均应力降低率，等于单轴抗压强度除以单轴压缩试验峰后岩石破坏的持续时间。其次，设计并进行了不同岩石类型的单轴压缩试验，详细研究了单轴压缩试验中B和随加载速率增加的变化趋势。结果表明，当加载速率大于5mm/min或100kN/min后，值受到影响，受加载速率限制，而值受应变率影响更大。建议采用0.1 - 0.7mm/min的加载速率进行位移控制来测量和。提出了2和的分类标准，并根据试验结果将和2的岩爆倾向性分为四个等级。
