Mechanical behavior of sandstone containing double circular cavities under uniaxial compression

Hole is one of the basic forms of micro defects in rock, and its fracture evolution mechanisms have become an important research subject in the field of rock mechanics. The uniaxial compression tests on tabular sandstone samples with pre-existing double circular cavities are conducted in order to investigate the effect of circle center distance 2b and angle α on strength, deformation and fracture evolution process of sandstone. The results show that both the peak strength and the elastic modulus of sandstone increase first and then decrease with the increase of the circle center distance 2b, and the peak strength and the elastic modulus reach their maximum values respectively when the circle center distance is 22 and 27 mm. With the increase of angle α, both the peak strength and the elastic modulus first decrease and then increase, and both of them reach the minimum values when the angle is 60°. The initial damage forms of the double circular cavities samples are all the collapsing destruction from the inner wall of the holes, and both the circle center distance and the angle have great influences on the stress levels of crack initiation, lap ways of holes and fracture evolution process.