Salt pillar creep analysis

Several salt deposits in the world were mined out by the room and pillar method. For the long term analysis of the pillar behaviour, we propose a new and simple method which can avoids using huge and expensive numerical modelling. The first part of this method deals with creep pillar behaviour by taking into account the mechanical interactions between a pillar and the surrounding roof and floor. This is achieved by means of finite element computations performed. These computations allow us to perform a substantial correction of the classical pillar's creep evaluation based on the tributary area method. Comparisons of data resulting from 3D modelling and in-situ data, with the results of our analytical method are finally presented. In this paper our analysis relates to only the viscoplastic (creep behaviour) but a similar analysis, not presented here, was carried out successfully in the analysis of the stability of such pillars.