The existing studies of ultimate pullout capacity of plate anchor which employed linear and nonlinear Mohr-Coulomb failure criterion have been achieved in sand. However

the Mohr-Coulomb failure criterion is unsuitable for calculating the ultimate pullout capacity of plate anchor in rock foundation. Based on the Hoek-Brown failure criterion

a curved failure mechanism is constructed and the expression of pullout capacity of plate anchor is derived in the framework of upper bound theorem of limit analysis. The upper bound solutions of ultimate pullout capacity and failure surface for plate anchor are obtained with the help of variational calculation. To evaluate the validity of this method

the ultimate pullout capacity of curved failure mechanism is calculated by using equivalent parameters of Mohr-Coulomb criterion when parameter B=1. The solutions are compared with the results presented in the existing literatures. The good agreement between the results of curved failure mechanism and the solutions computed by linear multiple blocks failure mechanism shows the upper bound solutions calculated by curved failure mechanism is effective. According to the results of parameters analysis

both the ultimate pullout capacity and failure surface decrease with the increase of rock parameter B when other parameters are fixed.