LIMIT ANALYSIS OF A STRIP LOAD ON THE HALF-PLANE USING A NOVEL EFFECTIVE STRESS FIELD AND NONLINEAR PROGRAMMING

Abstract

This paper presents a method to determine a strip load's actual failure load on the half-plane. Solving the problem of calculating natural stresses and deformations in the soil is a practically impossible task. An alternative may be formed by limit analysis based on plasticity theory. The fundamental theorems of the idea of plasticity (the upper and lower- bound theorems) aim to give a possible upper or lower limit of the stresses the deformations. For materials with friction, such as soil, for which the yield condition is the MohrCoulomb criterion, the limit theorems of plasticity are not good, except for ϕ = 0 (i.e., purely cohesive materials). For such a material, the theory predicts that the volume is constant during plastic deformations, which agrees with experimental evidence. Thus, the author proposes a novel effective stress field based on the shear potential having volume remains constant during plastic deformations, to properly apply the limit theorem. In this paper, the limit analysis is formulated in the form of nonlinear programming. Several numerical examples show that the novel effective stress field achieves high reliability compared with existing results.