Abstract:After analyzing the interaction mechanism between the rock mass and bolt in jointed rock mass,with the help of fracture mechanics method,the effect of bolt on stress intensity factor in joint tip under the mixed loading of tension and shearing is analyzed. Furthermore,the regularity of bolt effect under different loadings,different inclinations of bolt to the joint is revealed. The results demonstrate that the bolts alternate the stress intensity factors in joint tip and decrease the magnitude of stress intensive factor to affect rock failure. This may be the main reason that bolts reinforce the jointed rock mass.