EXPERIMENTAL STUDY ON THE TENSILE STRENGTH OF ROCK-LIKE MATERIALS CONTAINING TWO PRE-EXISTING COPLANAR FISSURES

It is of great importance to study the mechanical properties of rock containing filling fissures to ensure the stability of fractured rock mass. The filling and non-filling coplanar double-fissures Brazilian disc rock-like samples with different fissure angles are prepared and the Brazilian splitting tests were performed on a DNS 300 rock servo machine. Based on the test results, the influence of crack inclination and crack filling on the tensile strength of the specimens was analyzed. The crack propagation process was also analyzed based on its acoustic emission characteristics and a digital speckle system. The main conclusions are drawn as follows:Compared with non-filling samples, the crack filling increases the integrity of the sample to some extent and increases its tensile strength; regardless of whether the cracks of the sample are filled or not, the tensile strength is affected by the crack inclination. With the increase of the crack inclination, the tensile strength of the filled and non-filled specimens shows an downward trend gradually; the crack filling has little effect on the failure mode of the sample when the crack inclination angle α ≤ 15° and α=90°, but it has a great influence on the failure mode when 30° ≤ α ≤ 75°. As α increases, the failure modes of both filled and non-filled specimens change from tensile cracks to wing cracks in morphology.