Feedback of the empirical approach to design the room and pillar mines. Application on chalk mines (France)

Abstract : The goal of this study is to improve the analysis of the stability of pillars and to answer the question of the choice of the pillar strength using an empirical approach. The pillar strength depends mainly on two factors: the uniaxial compression strength and the pillar geometry.We have shownin this study the importance of geometry of pillars by comparing calculations with and without the effect of W/H ratio (slenderness). The sensitivity of the parametric study based on the empirical relationships converges to the same resistance of the pillar despite the difference between the coefficients of these empirical relationships. The methodology was applied to case studies (France). The application of these relationships can help to explain the collapse of Clamart mine (Paris). Generally, and in the absence of data, it will certainly be more prudent to use the relationships available taking into account the effect of uncertainty.