Numerical investigation on rockburst of excavated and unloaded roadway based on different stresses condition

Adopting Plaxis 3D simulation software，it takes a research about the rockburst in different stress environments，which puts the effects of different stress environments on rockburst as the breakthough point to analyze the rockburst in terms of cloud displacement，stress-strain curves and distribution of plastic points.And this research aims to provide basis for the prevention and control of rockburst.The results show that during the tunnel excavation，the rockburst tends to occur mostly when the stress concentration and displacement concentration are simultaneously present at both sides of the tunnel，according to the thickness relation between surrounding rock and side wall of the tunnel，the impact of the excavation on surrounding rock can be divided into three regions including “start larger”，“significantly increase” and “sharp increase”.Both sides of tunnel generate a high stress concentration and displacement concentration，the maximum stress increases linearly with the horizontal stress increasing，and the area of the displacement concentration takes an exponentially positive correlation with the horizontal stress.The distance between the displacement concentration and the side wall of the tunnel is about 2/5 of the tunnel radius.With the increase of stress，the displacement concentration is expanding to the surrounding area，and degree of rockburst is also increasing.