MICROMORPHOLOGY OF EXPERIMENTAL ROCK CRACKS

Short duration compression,extension and bending experiments of limestone and sandstone cylinders were made in the laboratory.The tensile microcracks produced by extension are closely spaced,leaving zigzag trails at an angle of less than 90 degrees to the extension uniaxial compression produced dominantly relatively long and straight ones,while bending gave rise to two sets of smooth fractures intersecting at an angle of more than 90 degrees towards bending.