Liu Guanlin, Chen Youliang, Du Xi, Xiao Peng, Liao Shaoming, Azzam Rafig
Department of Civil Engineering, School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, China.
Department of Engineering Geology and Hydrogeology, RWTH-Aachen University, 52064 Aachen, Germany.
Materials (Basel). 2021 Apr 21;14(9):2108. doi: 10.3390/ma14092108.
The cracking of rock mass under compression is the main factor causing structural failure. Therefore, it is very crucial to establish a rock damage evolution model to investigate the crack development process and reveal the failure and instability mechanism of rock under load. In this study, four different strength types of rock samples from hard to weak were selected, and the Voronoi method was used to perform and analyze uniaxial compression tests and the fracture process. The change characteristics of the number, angle, and length of cracks in the process of rock failure and instability were obtained. Three laws of crack development, damage evolution, and energy evolution were analyzed. The main conclusions are as follows. (1) The rock's initial damage is mainly caused by tensile cracks, and the rapid growth of shear cracks after exceeding the damage threshold indicates that the rock is about to be a failure. The development of micro-cracks is mainly concentrated on the diagonal of the rock sample and gradually expands to the middle along the two ends of the diagonal. (2) The identification point of failure precursor information in Acoustic Emission (AE) can effectively provide a safety warning for the development of rock fracture. (3) The uniaxial compression damage constitutive equation of the rock sample with the crack length as the parameter is established, which can better reflect the damage evolution characteristics of the rock sample. (4) Tensile crack requires low energy consumption and energy dispersion is not concentrated. The damage is not apparent. Shear cracks are concentrated and consume a large amount of energy, resulting in strong damage and making it easy to form macro-cracks.
岩体在压缩作用下的开裂是导致结构破坏的主要因素。因此，建立岩石损伤演化模型来研究裂纹发展过程并揭示岩石在荷载作用下的破坏与失稳机制至关重要。在本研究中，选取了四种从硬到软不同强度类型的岩石样本，采用Voronoi方法进行并分析单轴压缩试验及断裂过程。得到了岩石破坏与失稳过程中裂纹数量、角度和长度的变化特征。分析了裂纹发展、损伤演化和能量演化的三条规律。主要结论如下：（1）岩石的初始损伤主要由拉伸裂纹引起，超过损伤阈值后剪切裂纹的快速增长表明岩石即将破坏。微裂纹的发展主要集中在岩石样本的对角线上，并沿对角线两端逐渐向中间扩展。（2）声发射（AE）中破坏前兆信息的识别点能有效地为岩石断裂发展提供安全预警。（3）建立了以裂纹长度为参数的岩石样本单轴压缩损伤本构方程，能较好地反映岩石样本的损伤演化特征。（4）拉伸裂纹耗能低且能量分散不集中，损伤不明显。剪切裂纹集中且消耗大量能量，导致损伤强烈且易形成宏观裂纹。
