EXPERIMENTAL STUDY ON SURFACE CRACK GROWTH IN ROCK-LIKE MATERIALS IN UNIAXIAL TENSION

摘要

Direct tension experiments with adhesive have been carried out for rock-like materials. Surface crack is pre-fabricated by placing polyester thin plate in the specimen. The specimen is then subjected to direct tension experiment to study the surface crack growth. Throughout this study, it is found that direct tension experiment with adhesive can be adapted to most rock-like materials and the pre-fabricated surface crack influences significantly the fracture mode of the rock-like materials. The pre-fabneated surface crack growth initiates from the front face, where the surface crack is located. In the front face, the surface crack exhibits obviously the propagation mode of two-dimension through crack. However, owing to the influence of the pre-existing surface crack, ihe crack propagation then deflects through the specimen and finally the fracture on the back face is not perpendicular to the loading direction but at acute angle with the loading direction. It is concluded that the acute angle is related to the dip angle and the depth of the preexisting surface crack.