Multi-approach back-analysis of a roof bed collapse in a mining room excavated in stratified rock

Roof bed deformation mechanics is a complex topic in mining practice. There are a number of empirical, analytical and numerical techniques that can be used to analyze and design underground excavations in stratified rock masses. Each has particular drawbacks, however, so the use of just one approach in order to obtain consistent and economic designs is not practical. To deepen understanding of this topic, it is useful to study real failure in mines. In this paper we describe how a roof bed failure in an underground mine, excavated in a stratified rock mass, was back-analyzed using different approaches, namely, the empirical stability graph method, the analytical voussoir techniques, and the numerical discrete element method. The study enabled us to better understand the conditions of failure and to define the most significant parameters affecting the failure. It has also been shown how relaxation or loss of confinement stress can play an important role in roof bed deformation.