A Modified Failure Criterion With Scale Effect Parameter

The design of structures on or within a rock mass requires an estimate of the strength of the intact rock blocks within the mass. These blocks of rock can be many orders of magnitude greater in scale than the core samples typically tested. Including the scale effects into a failure criterion is important for better estimation of the rock strength. In this paper a modified failure criterion with scale effect parameter was developed based on the model proposed by Christensen [1]. The modification process was conducted based on the scale effect equations proposed for UCS and point load results and it was shown that for one particular sandstone the strength parameter of the modified failure criterion is scale independent.