Upper-bound limit analysis of soils with a nonlinear failure criterion

Limit analysis is a widely used technique for the analysis of geotechnical collapse states and there exists a significant body of literature covering its application to soils with a linear failure criterion. However, such a failure criterion is often an idealization of an actual nonlinear response for which available analytical techniques are limited. This paper presents a new fully general solution procedure for generating multi-wedge rigid-block upper-bound mechanisms for a soil with a nonlinear failure criterion, utilizing a curved interface that obeys the nonlinear yield function flow rule along its full length. This work extends the long-established kinematic sliding-wedge approach for linear soils and is illustrated through application to active and passive retaining wall and anchor–trapdoor problems. Through additional consideration of the lower-bound solution, close bounds on the retaining wall problem to within ∼1% are established. The ability of the nonlinear upper bound solution to predict the shear and normal stress at every point along the failure surface is discussed.