Abstract: Based on the fictitious loading upper bound limit analysis approach i.e. total-displacement-loading approach based on extend mobilizable strength design method (T-EMSD), by which the traditional upper bound limit analysis is equivalently converted into iteration of elastic solution, the elastic finite element based T-EMSD method is realized in commercial FEM software ABAQUS. The numerical T-EMSD method is applied to analyzing the shaft of laterally loaded pile in undrained clay. The load-displacement curves obtained by the proposed method are generally consistent with those obtained by elasto-plastic FEM, and the corresponding ultimate bearing capacities are close to plastic solutions. Under large displacements, the mechanisms underlining the elastic finite element based T-EMSD analysis transform from elastic into plastic mechanisms through iteration process, which finally become similar to the plastic collapse mechanisms. Compared with other mobilizable strength design (MSD) methods, the proposed approach are more accurate in the analysis of laterally loaded pile. Moreover, since corresponding mechanisms can be simultaneously obtained in the process of the numerical T-EMSD analysis, it can be utilized in studying complicated problems whose plastic deformation mechanisms are not acquired yet, and in verifying the results of other numerical methods.

Key words: T-EMSD method, finite element, stress-strain relationship, load-displacement curve, undrained clay