Shape Effect and Accuracy Analysis of Rock Tensile Strength Test

To investigate the influence of shape effects on the tensile strength of rocks, splitting tests were conducted on disc specimens with the same thickness-to-diameter ratio but different diameters using physical similarity simulation and numerical simulation experiments. Additionally, finite element analysis software was employed to perform numerical simulation tests on two types of dumbbell-shaped specimens involved in direct tensile tests of rocks. This study revealed that when the thickness-to-diameter ratio is fixed at 0.5, the splitting tensile strength decreases gradually as the specimen diameter increases from 30 mm to 110 mm. This trend can be well fitted using a power function. The tensile strength measured from direct tensile tests on the two types of dumbbell-shaped specimens shows a slight decreasing trend as the diameter of the central effective test area decreases. Moreover, the measured tensile strength is lower than the actual tensile strength. The test results for disc specimens are the closest to the actual tensile strength, followed by arc-transition dumbbell-shaped specimens, and lastly, straight-transition dumbbell-shaped specimens. The correlation coefficients between the test results and the actual tensile strength for the three types of specimens are also provided.