岩石张拉、剪切裂纹划分方法及其在岩爆前兆中的应用

Division method of tensile and shear crack and its application in sandstone rockburst precursor

提出一种利用支持向量机划分张拉裂纹和剪切裂纹的方法,采用巴西劈裂试验和直剪试验的验证结果证明该方法合理有效。在此基础之上,对砂岩应变岩爆全过程裂纹类型进行划分,并分析各类裂纹事件数、事件增长速率及占比变化规律。研究结果表明:岩爆全过程经历张拉裂纹主导、张拉和剪切裂纹共同作用、岩爆发生3个阶段;在岩爆时刻前张拉和剪切裂纹都出现突增的现象,且张拉裂纹事件增速大于剪切裂纹增速,但张拉裂纹累计占比下降、而剪切裂纹累计占比上升。岩爆前张拉裂纹累计占比下降的现象早于裂纹事件数和事件率突增的现象,且具有较强的前兆响应能力,可作为岩爆的一种前兆特征。

A division method on tensile and shear crack of rock based on support vector machine was proposed.Reasonableness and validity of the method was proved by the results of brazilian splitting test and direct shear test.Furthermore,the cracks of sandstone rockburst were divided,and the number of various crack events,the event growth rate and the change law of the proportion were analyzed.The results show that rockburst experiences three stages,which could be described as tension cracks dominated,the joint action of tension and shear cracks and the occurrence of rockburst.Tensile cracks have a higher growth rate than shear cracks before the moment of rockburst,but tensile cracks have a decreased tendency of the cumulative proportion.The time of decreasing in cumulative tension cracks is earlier than that of increasing in the number of crack events and event rate,and has a strong precursor response ability,which can be used as a precursor to rockburst feature.