北山花岗岩断裂力学行为及其声发射特征研究

Fracture mechanical behaviors and acoustic emission characteristics of Beishan granite under CCNBD test

利用MTS815 Flex Test GT岩石力学试验系统及声发射(AE)三维定位实时监测系统,对北山花岗岩试样开展静态加载和循环加载两种加载方式的人字形切槽巴西圆盘(CCNBD)试验,旨在研究不同加载方式下北山花岗岩的断裂力学行为及声发射特征。测试结果表明,北山花岗岩在静态加载下的平均断裂韧度值为1.180 MPa·m^(1/2),循环加载下的平均断裂韧度值为1.153MPa·m^(1/2),循环加载下岩石的断裂韧度降低了2.3%。通过循环加载试验证实了亚临界裂纹扩展的存在,并发现循环加卸载并不会改变CCNBD试样的破坏模式,试样仍保持脆性特征。结合力学特征曲线和声发射特征,对静态加载及循环加载下CCNBD试样的裂纹扩展过程进行分析,深化对不同加载方式下的CCNBD试样断裂特征的认识。

To investigate the fracture mechanical behaviours and acoustic emission characteristics of Beishan granites,the MTS815 Flex Test GT rock mechanics testing system and acoustic emission(AE) three-dimensional positioning monitoring system are used to conduct Cracked Chevron Notched Brazilian Disc CCNBD tests with two different loading modes(static loading and cyclic loading). Experimental results show that mean value of KIC under static loading is 1.180 MPa·m^(1/2),while mean value of KIC under cyclic loading is 1.153 MPa·m^(1/2),which is reduced by 2.3%. The existence of subcritical crack growth is verified by cyclic loading test,and it is turned out that the failure mode of CCNBD specimens under cyclic loading do not change,the specimens are still brittle. Based on the mechanical characteristic curves and acoustic emission characteristics,the fracture propagation process and fracture characteristics of CCNBD specimens under static and cyclic loading are studied.