Abstract:  The influence of a nonlinear strength envelope is considered in the framework of the limit analysis of plasticity.The passive earth pressure on the rigid walls is estimated using the upper bound theorem of the limit analysis in conjunction with the nonlinear failure criterion.A generalized tangential technique,multi-tangential line to the nonlinear failure criterion,is used to import the variable Ct and ? t for the first time.Based on the upper bound theory,the multi-triangle failure mechanism is considered,some basic formulae are deduced,and the minimum upper bound solutions of passive earth pressure are presented by applying a nonlinear sequential quadratic programming(SQP) algorithm.From the numerical results,it can be seen that the solutions are reasonable and rigorous upper-bound ones.