关键词: 中心直裂纹圆盘试件, 应力强度因子, 岩石断裂韧性, 临界加载角, 数值标定

Abstract: Rock fracture toughness is a factor describing the ability of resisting rock crack propagation, and the dimension-less stress intensity factor (DSIF) is an essential parameter to calculating the fracture toughness. At present, many scholars still adopt the approximate formula given by C.Atkinson for the central straight through Brazilian disc specimen to obtain the DSIF values. We research the accuracies of C.Atkinson formula and the series solution for the center crack disk specimen, and put forward the loading conditions of pure type II crack at a wide range of load angle and relative crack length. We also adopt finite element method to calculate the dimensionless stress intensity factor of crack I for CSTBD specimens with different prefabricated crack width. The analysis results show that YI gradually decreases with increase of the relative crack width, and the change amplitude of YI gradually reduces after the relative crack width exceeds 0.01; for the different crack width, the change law of YI is the same. In addition, when the crack width is only 0.1mm, the analytical solution of DSIF will deviate from the numerical solution. Therefore, in the fracture toughness test, the dimensionless stress intensity factor must be calibrated by the measured crack width.

Key words: central straight through Brazilian disc, stress intensity factor, rock fracture toughness, critical load angle, numerical calibration