The Effect of Linearization of Hoek-Brown Criterion on the Bearing Capacity of Rock Masses using the Upper Bound Method of Limit Analysis

One of the most important issues in calculation of the bearing capacity of rock masses is the method of application of rock mass failure criterion. The Hoek-Brown failure criterion is the most useful criterion in practical applications. For applying this criterion in upper bound method of limit analysis, one should linearize it using the single or multi tangential technique. In this paper, the method of linearization of the Hoek-Brown criterion is investigated for determining the bearing capacity of embedded footings on rock masses. Since different stress levels are existed in the rock mass body, the multi-tangential technique results in the best approximation of the nonlinear Hoek-Brown criterion. As a novelty for the current research, the embedment depth of the footing is considered directly in the upper bound formulations instead of replacing it by an equivalent surcharge. The obtained results show that considering the embedment depth of footings along with using the multi-tangential technique result in increasing the accuracy of the results. In the methods which consider the embedment depth as an equivalent surcharge, the extension of the failure lines through the rock mass above the footing base cannot be considered.