A short- and long-term rheological model to understand the collapses of iron mines in Lorraine, France
Résumé
Mining collapses currently occur in Lorraine (France) above abandoned room-and-pillar iron mines. The mechanical behaviour of iron ore and marls was investigated using experimental studies (triaxial, hydrostatic and creep tests). Following this, an elasto-plastic constitutive law, with two strain hardening rules, is proposed to model the transition from hardening to softening. A creep constitutive law, which describes the delayed volumetric dilatancy of iron ore, is also proposed. Both laws have been implemented in a two-dimensional finite difference code (FLAC2D). The object of this modelling is to understand and predict the phenomena involved in the mining collapses. The results of numerical simulation show that the ageing of iron ore has to be considered when attempting to explain mining collapses