Finite element analysis of the plastic limit load and the collapse mechanism of strip foundations with non-associated Drucker-Prager model

摘要

This paper is devoted to the numerical study of the influence of the non-associativity of the Drucker-Prager model on the plastic limit load and the failure mechanism of the strip footings. The attention is mainly focused on the determination (estimation) of the mechanical fields and geometric characteristics of the collapse mechanism. Rough and smooth contact between the punch and the substrate are considered. Analyses were performed by incremental finite element simulations by using of the object oriented computer code Cast3m. The code is first validated against analytical solutions for two problems available in the literature. It is worth noting that during this validation, we provide new numerical results concerning the ultimate load of a pressurised pore with non-associate matrix. Then, the limit plastic load of the weightless soil is computed and the post-treatment of the numerical results permits one to select the relevant mechanical fields. The main result is that, for the Prandtl mechanism associated to the rough footing, the angle base of the triangular wedge under the footing is independent of the dilatancy angle. This property appears to be very interesting and useful when constructing analytical bounds of the plastic limit load within the framework of limit analysis.