Consideration of fracture growth from an inclined slit and inclined initial fracture at the surface of rock and mortar in compression

摘要

Compression tests on rock and mortar specimens with an inclined slit from the specimen surface or an inclined initial fracture from the specimen surface were performed. The observed fracture growth was numerically simulated employing a new criterion. The main results were as follows. (1) The fracture from the inclined slit from the specimen surface grew at a small angle to the initial direction and curved slightly towards the free surface in all cases for rock specimens and in two of four cases for mortar specimens. (2) The fracture from the inclined initial fracture from the surface of mortar specimens grew almost parallel to the initial fracture. (3) Simulation employing the proposed method, which considers shear fracture growth as well as tensile growth, gave much better results than the widely used Sih method. Some problems remain to be resolved in the method described here. The present method is empirical and the physical significance of O_s is not yet clear. Continued improvement of this method will allow more practical analysis of fracture growth in rock and rock masses.