STUDY ON MECHANICAL BEHAVIOR OF HARD ROCK TUNNEL IN HIGH GEO-STRESSES AND OPTIMIZATION OF ROUND LENGTH IN ROCK BURST AREA

摘要

In this paper, three-dimensional finite difference numerical simulation method considering the strain softening effect is conducted to investigate the occurrence of rock burst in the Daxiangling tunnel through the hard rock layer in high geo-stresses. The results show that the deep-lying hard rock runnel subjected to the high geo-stresses has the mechanical characteristics of stress-strain orthogonality, which is completely different from that subjected to common geo-stresses. So the occurrence location of rock burst usually is perpendicular to the orientation of the maximum geo-stress. Furthermore, it is found that for the Daxiangling expressway tunnel the rational round length in rock burst area should be limited to about 2 m.