期刊
ROCK MECHANICS AND ROCK ENGINEERING
卷 49, 期 10, 页码 3865-3872出版社
SPRINGER WIEN
DOI: 10.1007/s00603-016-0958-4
关键词
Fracture toughness; Pre-load; SHPB; NSCB; FEM
资金
- Natural Science Foundation of China (NSFC) [11202232, 51479131]
- Open Foundation of State Key Laboratory of Explosion Science and Technology (Beijing Institute of Technology) [KFJJ15-04M]
- Natural Sciences and Engineering Research Council of Canada (NSERC) [72031326]
A dynamic load superposed on a static pre-load is a key problem in deep underground rock engineering projects. Based on a modified split Hopkinson pressure bar test system, the notched semi-circular bend (NSCB) method is selected to investigate the fracture initiation toughness of rocks subjected to pre-load. In this study, a two-dimensional ANSYS finite element simulation model is developed to calculate the dimensionless stress intensity factor. Three groups of NSCB specimen are tested under a pre-load of 0, 37 and 74 % of the maximum static load and with the loading rate ranging from 0 to 60 GPa m(1/2) s(-1). The results show that under a given pre-load, the fracture initiation toughness of rock increases with the loading rate, resembling the typical rate dependence of materials. Furthermore, the dynamic rock fracture toughness decreases with the static pre-load at a given loading rate. The total fracture toughness, defined as the sum of the dynamic fracture toughness and initial stress intensity factor calculated from the pre-load, increases with the pre-load at a given loading rate. An empirical equation is used to represent the effect of loading rate and pre-load force, and the results show that this equation can depict the trend of the experimental data.
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