Self-drilling Rock Bolt used as an efficient anchoring means, in tunnel pre-support, slope stabilization , coast, mine, Structure of self-drilling bolt I. Self-drilling hollow anchor bar Outer sidediameterAverageInternaldiameterEffectiveexternaldiameterAver.eff.CrosssectionalareaUltimateloadcapacityYieldloadcapacityAveragetensilestrengthRmAverageyieldstrengthRp0,2TheoricalweightThreadtype ...