A New Method of Investigating Shear Failure of Rock

A new method applied to test direct shear is developed and tested on sandstone with a constant normal load. A CCD camera and stereomicroscope were employed to record crack fractures of specimen surfaces and rock damage was recorded by an acoustic emission monitoring system. During the shearing process, AE signal changes were found to indicate crack initiation and propagation on the surface of specimens. Micro-cracks were observed on the specimen surfaces, including different genesis tension cracks, shear cracks, and rock bridges. Crack growth both along and through particles was clearly observed.