Application of a hierarchical solution scheme to the analysis and design of large-scale tabular mine layouts

Abstract

This paper outlines a hierarchical computational strategy for solving large-scale tabular deposits using the displacement discontinuity boundary element method. This scheme facilitates the detailed analysis of local regions of interest, where current mining activity is in progress. The suggested approach requires an overall solution of the mine layout with a coarse element mesh to be obtained, which is then used to generate the background stress field for fine-scale solutions in selected regions of interest. The fine mesh solutions are established using the appropriate induced external coarse solution stress influence calculated in the selected region of interest using high order elements. The fine-scale solutions may involve detailed excavation extensions or time-dependent crushing of the fracture zone adjacent to the mined excavation edges. This analysis may require periodic re-calculation of the coarse scale background influence. An additional influence matrix partitioning scheme is also proposed as a strategy to incorporate automatically the effect of the induced background stress influence. A case study simulating the time-dependent convergence of a mining panel in a large-scale shaft pillar geometry is used to illustrate these hierarchical solution schemes.

HIGHLIGHTS • This paper illustrates a hierarchical computational strategy for solving large-scale tabular layouts using the displacement discontinuity boundary element method. Particular attention is given to addressing the accuracy of the scale transition between coarse and fine mesh calculations using high order elements. • The beneficial use of influence matrix partitioning in local regions of interest allows an efficient analysis of the time-dependent evolution of the fracture zone for stability modelling and the assessment of adverse ground conditions, where current mining activity is in progress. • A simulation of the time-dependent convergence of a mining panel in a large-scale shaft pillar geometry is presented to illustrate the application of the proposed procedure. • Time-dependent convergence profiles similar to those recorded in underground panels can be simulated.