Investigation on fracture toughness and micro-deformation field of SCB sandstone including different inclination angles cracks

•A comprehensive method combined with GCTS, RFPA and DIC was developed to study the failure of rock.•The stress singularity of the loading point has obvious attraction to crack propagation.•As the inclination angles increase, the variation law of KI is different from that of KII at failure.•Whole failure process and AE behavior of rock with I/II mixed mode crack were reproduced by RFPA2D.•The evolution characteristics of micro deformation field at crack tip were investigated with DIC.