Crack coalescence behavior of brittle sandstone samples containing two coplanar fissures in the process of deformation failure

This investigation presents crack coalescence behavior of brittle sandstone samples containing two coplanar fissures in the process of deformation. On basis of experimental results, the influence of coplanar fissure angle on strength and deformation behavior of sandstone samples is firstly analyzed. By adopting photographic monitoring, the crack initiation and coalescence are all observed and characterized from the inner and outer tips of pre-existing coplanar fissures in brittle sandstone sample. Moreover, the sequence and type of crack coalescence in sandstone samples containing two coplanar fissures are analyzed. Finally, the relationship between coplanar fissure angle and crack coalescence stress is constructed.