Mechanical response and microscopic damage mechanism of pre-flawed sandstone subjected to monotonic and multilevel cyclic loading:A laboratory-scale investigation  

作　　者：Kesheng Li Shengqi Yang Chuanxiao Liu Yun Chen Guanglei Zhang Qing Ma 

机构地区：[1]State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering,China University of Mining and Technology,Xuzhou 221116,China [2]School of Mechanics and Civil Engineering,China University of Mining and Technology,Xuzhou 221116,China [3]College of Water Conservancy and Civil Engineering,Shandong Agricultural University,Tai’an 271018,China [4]School of Civil and Transportation Engineering,Hebei University of Technology,Tianjin 300401,China [5]State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084,China

出　　处：《International Journal of Mining Science and Technology》2023年第12期1487-1510,共24页矿业科学技术学报（英文版）

基　　金：This work was financially supported by the National Natural Science Foundation of China(Nos.42077231 and 51574156).

摘　　要：This study aims to investigate the mechanical response and acoustic emission(AE)characteristic of pre-flawed sandstone under both monotonic and multilevel constant-amplitude cyclic loads.Specifically,we explored how coplanar flaw angle and load type impact the strength and deformation behavior and microscopic damage mechanism.Results indicated that being fluctuated before rising with increasing fissure angle under monotonic loading,the peak strength of the specimen first increased slowly and then steeply under cyclic loading.The effect of multilevel cyclic loading on the mechanical parameters was more significant.For a single fatigue stage,the specimen underwent greater deformation in early cycles,which subsequently stabilized.Similar variation pattern was also reflected by AE count/energy/b-value.Crack behaviors were dominated by the fissure angle and load type and medium-scale crack accounted for 74.83%–86.44%of total crack.Compared with monotonic loading,crack distribution of specimen under cyclic loading was more complicated.Meanwhile,a simple model was proposed to describe the damage evolution of sandstone under cyclic loading.Finally,SEM images revealed that the microstructures at the fracture were mainly composed of intergranular fracture,and percentage of transgranular fracture jumped under cyclic loading due to the rapid release of elastic energy caused by high loading rate.

关 键 词：SANDSTONE Pre-existing coplanar flaws Multilevel constant-amplitude cyclic loading Mechanical behavior Microscopic damage mechanism 

分 类 号：TD313[矿业工程—矿井建设]