单调及循环加载下大理岩断裂特性研究  

Study on fracture characteristics of marble under monotone and cyclic loading

作　　者：张琰 李江腾[1] ZHANG Yan;LI Jiangteng(School of Resources and Safety Engineering,Central South University,Changsha,Hunan 410083,China)

机构地区：[1]中南大学资源与安全工程学院,湖南长沙410083

出　　处：《岩石力学与工程学报》2019年第S02期3313-3320,共8页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51979293,51374246)。

摘　　要：基于大理岩的室内基本力学试验,使用PFC3D获取一组真实反映大理岩特性的细观参数。在此基础上对大理岩人字形切槽圆盘(CCNBD)模型分别进行单调和循环加载,研究不同荷载作用下大理岩的应力分布及断裂韧度、裂纹扩展规律。研究结果表明:逐级和等幅2种循环荷载作用下,大理岩的Ⅰ型断裂韧度均有不同程度降低,且峰后会产生明显的应变软化阶段,发生亚临界裂纹扩展;循环荷载作用下试样的裂纹扩展存在明显初期、稳定、加速3个阶段,微裂纹在加载初期增加明显,裂纹扩展速率稳定,在稳定阶段裂纹扩展速率逐渐降低,最后加速阶段裂纹扩展速率逐渐增大,裂纹数目快速增加直至破坏;拉力链分布相对于单调加载更集中在韧带两端和圆盘两边。Based on the laboratory basic mechanical tests of marble, the PFC^3D was used to obtain a set ofmesoscopic parameters reflecting the characteristics of marble. Monotone and cyclic loading of cracked chevronnotched Brazilian disc(CCNBD ) model were carried out respectively to study the stress distribution, fracturetoughness and crack propagation law of marble under different loadings. The results show that the mode-Ⅰ(tensile)fracture toughness( KIC ) of marble under two types of cyclic loading have different amplitude reduction of the staticKIC , and the specimens have clear tensile softening zone after the post-peak region, and subcritical crack propagationoccurs. Under cyclic loading, the crack growth of the sample can be divided into three stages: initial stage, stable stageand accelerated stage. At the initial stage of loading, the number of microcracks increased significantly, and the crackgrowth rate was stable. At the stable stage of loading, the crack growth rate gradually decreased, and finally, the crackgrowth rate gradually increased, and the number of cracks increased rapidly until failure. The tensile chain distributionwas more concentrated at both ends of the ligament and on both sides of the disc than the monotonic loading.

关 键 词：岩石力学 断裂韧度 循环荷载 亚临界裂纹 颗粒流 拉力链 

分 类 号：TU45[建筑科学—岩土工程]