基于DIC方法下板岩动态巴西劈裂试验的变形破坏研究

Damage Study of Dynamic Brazilian Splitting Test in Slate Based on DIC Methodology

摘要: 巴西劈裂法是国际上用以测试岩石抗拉强度最广泛的方法，其优点在于成本低廉，方法简单，测试环境要求低，近年来有不少学者利用SHPB装置测试动态岩体的抗拉强度，但对于此方法下影响岩石动态抗拉强度准确度的因素并不清楚。本文利用SHPB装置进行了层状板岩的动态巴西劈裂试验，并借助高速摄影仪和数字图像相关技术(DIC)分析了动态测试下板岩的破坏形态和微应变分布云图，发现层理角度不同，试样内部的微应变分布也会发生改变，而层理角度为75˚时岩石的破坏模式从拉伸破坏变为剪切破坏模式。这表明动态巴西劈裂测试方法对于层状岩体的抗拉强度精度影响较大，当岩石的破坏模式发生改变时，既不满足中心起裂准则，也不满足拉伸破坏原则，此时测试精度误差最大。

Abstract: The Brazilian splitting method is the most widely used method to test the tensile strength of rocks in the international arena, and its advantages include low cost, simple method, and low requirement of testing environment, etc. In recent years, a number of scholars have utilized the SHPB device to test the tensile strength of dynamic rock bodies, but the factors affecting the accuracy of the dynamic tensile strength of rocks under this method are not clear. In this paper, the dynamic Brazilian splitting test of laminated slate was carried out using the SHPB device, and the damage pattern and microstrain distribution cloud map of the slate under the dynamic test were analyzed with the help of high-speed camera and digital image correlation (DIC), and it was found that the microstrain distribution inside the specimen would change with different angles of the laminae, and the damage mode of the rock at the laminae angle of 75˚ was changed from the tensile damage to the shear damage mode. This indicates that the dynamic Brazilian splitting test method has a greater impact on the accuracy of the tensile strength of the laminated rock body, and when the damage mode of the rock is changed, it does not satisfy either the center initiation criterion or the tensile damage principle, and the testing accuracy error is the largest at this time.