Ⅱ型断裂韧度测试功能开发与试验分析

Test function development and experimental analysis of mode Ⅱ fracture toughness

断裂韧度作为岩石的重要力学指标,对认识压剪破坏规律具有重要意义。为解决现有设备缺乏围压冲剪试验(PTS/CP)测试功能的问题,本文基于Ⅱ型断裂韧度测试方法进行试验装置开发,在现有设备上实现了PTS/CP测试功能,并通过青砂岩的PTS/CP试验验证了开发装置的可靠性。青砂岩PTS/CP试验结果表明,在围压侧向约束条件下岩石试样可获得较理想的冲剪破坏面,且随着围压的增大,Ⅱ型断裂韧度K_(ⅡC)先增大后趋于稳定;通过PTS/CP试验所获得的青砂岩K_(ⅡC)与其单轴抗拉强度、I型断裂韧度指标之间的关系符合常规认识,说明了PTS/CP测试功能的合理性和装置的可操作性。PTS/CP测试功能的开发可为岩石及类似工程材料的相关教学和科研工作提供试验支撑。

As an important mechanical index of rock,fracture toughness is of great significance to understanding the compression-shear failure.In order to carry out a punch-through shear test with confining pressure(PTS/CP),the test function was developed based on the existing equipment,and the PTS/CP experiment research of green sandstone was carried out.The test results show that under the constraint of confining pressure,the rock has an ideal punching shear failure surface,and with the increase of confining pressure the mode Ⅱ fracture toughness(K_(ⅡC))first increases and then tends to be stable.The relationship between(K_(ⅡC))obtained through PTS/CP,uniaxial tensile strength,and mode Ⅰ fracture toughness index of green sandstone conforms to the conventional understanding,which shows the reliability and effectiveness of this functional development,and it can provide experimental support for the related teaching and scientific research.