Analytical derivations of bolt profile shear strength
This paper presents current developments in theoretical calculations of stress distribution within the resin encapsulating roof bolts in underground mines. Monitoring of steel bolt performance indicate that amongst many parameters bolt profile plays an important role in load transfer between the bolt and the surrounding strata.To optimise the bolt profile geometry a better understanding of the failure mechanisms that occur within the resin during the bolt loading must be achieved. The short encapsulation pull out tests of roof bolts with various surface profile geometry indicate a significant variation in peak bolt performance. The analytical calculations supported by the numerical modelling are used here to predict a probable mode of resin failure while the laboratory and the in situ short encapsulation pull out tests enable direct comparison to the theoretical investigations. The aim of the theoretical predictions and experiments is to research the best profile geometries to reach the optimum load transfer between the bolt and the surrounding strata.