Towards efficient and robust elements for 3D-soil plasticity

The performance of several mixed formulations that can be developed for the eight-noded brick element is scrutinized for dilative or contractive plast ic flow which occurs in constitutive models for cohesive-frictional materia ls such as clay, sand and rock. Special attention is given to the phenomeno n of element locking under dilative/contractive conditions and to the robus tness of different mixed formulations for conditions of plastic flow. Analy tic considerations and numerical simulations of elementary tests will be pr esented to explain and to underline the importance of the above mentioned p henomena. A three dimensional calculation of the bearing capacity of a squa re footing will be given to demonstrate the relevance and the applicability of the developed formulations. (C) 1998 Elsevier Science Ltd. All rights r eserved.