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2020-01-13 - Travail avec promoteur/Projet d'étudiant - Anglais - page(s)

Georgieva Temenuga Dimova , "2D and 3D modeling for stability analyses of a shallow abandoned chalk quarry of malogne (belgium)", 2020-01-13

  • Codes CREF : Mécanique des roches (DI1418)
  • Unités de recherche UMONS : Génie Minier (F408)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux), Institut des Sciences et du Management des Risques (Risques)

Abstract(s) :

(Anglais) This work has been carried out at the Mining Engineering Department at Polytech Faculty, the University of Mons under the supervision of Prof. Jean-Pierre TSHIBANGU, Ir. Ph.D. Fanny DESCAMPS and Ir. Nicolas GONZE. The work provides a parametric study on the stability of a shallow underground quarry, named “Malogne”, located in the area of Mons (Cuesmes), Belgium. It is conducted in the framework of the INTERREG project “RISSC” and a doctoral formation program at UMONS, which is a partner in the “RISSC” project. The Malogne underground quarry is situated in the central part of the Mons sedimentary Basin, in the area of the Cuesmes village, Mons district. The deposit is with Late Cretaceous age and has been exploited due to the content of phosphate in the chalk of the geological formation known as “Craie Phosphatée de Ciply”. The Malogne phosphatic chalk quarry was developed by the rooms and pillars mining method within an area of 67 ha. The site is partially flooded and located in close proximity to important infrastructure as railway, highway, and residential houses. During and after its exploitation several significant ground collapses were registered. The last one, with an area of 1.2 ha and 3 m amplitude occurred in 2015 nearby the railway line. To assess the behavior of the underground openings a combination of in situ structural measurements and laboratory mechanical characterization of the main lithology types in the quarry - white and phosphatic chalk, hardground and calcarenites, are performed. The data obtained was implemented in a conceptual geomechanical model of the underground openings in the Malogne quarry, using the 2D Finite Element Method (FEM). Due to the lack of reliable information on the initial stress-field in the rock mass, the calculations are performed for several variations. The rock mass behavior under different in situ stress conditions is studied and the influence of the initial stress on the overall stability of the pillars in the quarry is evaluated. The modeling included seven different values of the k ratio (horizontal vs. vertical stress) under which the rock mass respond was analyzed. As a result, the evolution of the induced stress in the rock mass was observed such as by increasing the values of the k ratio (the horizontal stress is higher than the vertical one) in general the rock mass is less stable, expect the significantly reduced number of the yielded elements. In addition, a three-dimensional model of a pillar and the hosting rock was created using the Rocscience RS3 Finite Element software. Similar conditions and mechanical parameters of the rock mass were used for the model. This allows a comparison between the results of the 2D and the 3D models to be done. On this base, some conclusions have been drawn. Acknowledgments: This research was supported by the Interreg “RISSC” project. The authors thank the team of L’ASBL Projet Malogne for their support during the fieldwork.