7. As a conclusion: advice and perspectives

This note proposes a methodology that allows excavation calculations to be carried out using Code_Aster. Several excavation scenarios are reviewed and several methods are proposed.

The method and the software package are validated in the case of a circular gallery, dug into an infinite mass constituted by a linear elastic material. Code_Aster reproduces in a completely satisfactory manner the behavior of such an underground structure, with or without taking into account the support and/or the coating.

From the user’s point of view, it seems more practical and faster to initialize the constraints by calling the CREA_CHAMP command rather than by calculating on fictional material.

If one seeks to model purely mechanical behavior and if the phasing of the excavation is relatively simple, working with a single model seems to be the easiest method. It is enough to assign very low material properties to the meshes that become « empty ». In more complicated cases, the implementation of several models used successively may prove to be more reliable from the point of view of practical implementation (modeling error) and from a numerical point of view (calculation error), despite the intermediate procedures for transferring fields (constraints, movements, movements, pressures, temperatures, internal variables…) from one model to another.

A subsequent validation step of the Code_Aster can be done on linear coupled problems (THM in a saturated and elastic medium) or coupled and/or non-linear problems (model CJS 1 similar to the Mohr-Coulomb model, short-term excavation in undrained to be compared with [3]).