Abstract：
The Nibashan tunnel is the key project on the Ya'an-Lugu highway, and rockbursts occur frequently after excavation due to the depth, high geostress, and brittleness of the surrounding rock. Thus it is necessary to effectively prevent and treat rockburst in order to ensure the safety of personnel and equipment. Using this project as a background, this paper analyzes the effects of such preventive measures as sprayed concrete and rockbolts and compares different bolt lengths and spacings using a numerical model. The results indicate that the application of sprayed concrete and rock bolts can reduce the maximum principal stress, increase the minimum principal stress, reduce the difference of principal stress, and effectively reduce the intensity of rockbursts. It is very cost effective to use the 3m rock bolt with a spacing of 1m.
2012, Vol. 49 