The authors pointed out that the formula existed for more than 40 years to calculate the tensile strength of rock in Brazilian test is based on 2D elastic theory; and the formula is not suitable for the practical condition which is a 3D problem. In order to obtain 3D stress distribution within the specimen

we adopted software package Marc to carry out a 3D finite element analysis. It is found that the tensile stress distribution at a cross-section of a solid specimen is similar to that of 2D disk. However

the tensile stress at a cross-section varies with the thickness of the specimen. The nearer the cross-section closes to the end of the specimen

the higher the horizontal tensile stress is. When the height-to-diameter ratio of the specimen is 1 and Poisson’s ratio is 0.25

the tensile strength calculated by the classical 2D solution is 23.3% less than the real value.