DIFFERENCE OF PLASTIC ZONE BY YIELD CONDITIONS

Abstract

A. A. Griffith is the only one that clarified physical mechanism of brittle failure. In this paper, the authors suggest new application of his yeild condition for reason that Griffith's theory is not adapted to rock. The plastic zone produced in the excavation of tunnel by using yield conditions is discussed in consideration of brittleness. The authors got the following conclusions.: 1) Plastic zone decreaces with increasing brittleness or increasing tensile strength. 2) Rock failure machanism can be estimated by failure parameter. 3) Rock burst growing index is suitable for studying rock burst. 4) The rock burst is not explained only by strain energy. 5) The peaks of plastic zone are not the very same as portions of rock burst.