1. Introduction

Designed in the 1960s to describe the behavior of normally consolidated clays [RoBu68] _, the modified Cam-Clay behavior model represents the essential phenomenology of soils granular under monotonous and drained loads: expansion or contraction and softening or hardening, regimes controlled by the evolution of volume plastic deformation, as well as the critical state. This internal variable is the only work-hardening variable in the model.

Using state parametrization in the plasticity criterion by the work hardening variable, the modified Cam-Clay model fits into the framework of Generalized Standard Materials [Hang75] _. Consequently, a resolution of the behavioral equations relating to a variational principle can be proposed, allowing advantageous to ensure the existence and the uniqueness of the problem of incremental evolution of internal variables. The robustness of the digital integration of The modified Cam-Clay model is therefore greatly strengthened for the calculation of geotechnical structures in Code_Aster.

This document summarizes essential information about the layout of the modified Cam-Clay model, as well as the resolution of its behavioral equations in MFront [HMPS15] _. It updates the formulation and numerical resolution method of the CAM_CLAY [r7.01.14] _ model, while remaining faithful to the phenomenology elements predicted by the model.