CCNBD断裂韧度试样的SIF新公式和在尺度律分析中的应用

根据国际岩石力学学会于1995年推荐的一种测试岩石断裂韧度的新型试样－人字形切槽巴西圆盘试样，对其断裂韧度计算公式中的关键参数即无量纲应力强度因子（SIF）提出了一个改进的计算公式。采用分片合成方法结合有限元法对CCNBD试样的应力强度因子进行了宽范围标定，结果以表格的形式给出；并采用数据线性回归的方法，将标定结果以一个指数函数的形式给出。结果表明，与标定值相比，无量纲应力强度因子新公式的误差较小，并且囊括了CCNBD试样的较宽范围的尺寸，且查表使用方便，也为理论分析提供了条件。在此基础上，对岩石断裂韧度测试的尺度律进行了更进一步的探索，结果表明，利用新公式进行的尺度律分析是有效的。

A new stress intensity factor formula of cracked chevron notched Brazilian disc (CCNBD) and its application to analyzing size effect

International Society for Rock Mechanics (ISRM) proposed in 1995 a new type of rock fracture toughness specimencracked chevron notched Brazilian disc (CCNBD); however, the calibration of the dimensionless stress intensity factor (SIF), which is an important mechanical parameter for fracture toughness calculation, is still in question. In authors previous paper, the new and more accurate wide range calibration values, listed as tables, are obtained by using a new slice synthesis method combined with finite element method. In order to guarantee the consistency of the table with ISRM, linear regression is adopted to obtain the lists of calibration with exponent function. The results show that the error of the new formula, compared with the values of calibration, is very small; and that it allows application for a wide range of specimen dimensions and further theoretical analysis. Based on this new formula of dimensionless stress intensity factor, size effect law of rock fracture toughness test is further discussed. The result of analysis with application of the new formula is proved to be reliable.