Numerical Study of Mine Site Specific Multiseam Mining and Its Impact on Surface Subsidence and Chain Pillar Stress

Abstract

This paper investigates various multiseam mining related parameters using mine site specific data and numerical simulations. Two important mining effects-subsidence and stress-are analysed for different possible mining layouts. A geological mine dataset has been used to generate a numerical model. The predicted surface subsidence magnitude and surface profile have been compared under different scenarios to assess potential options in multiseam mining strategies. The effects that seam separation distances, mining offset, panel layout and panel orientation each have on surface subsidence and chain pillar stress magnitude have been investigated. The numerical simulation shows that ascending or descending mining directions have little impact on controlling the surface subsidence in multiseam mining and predicted an almost identical maximum stress development at the chain pillars. Numerical simulations infer that the orientation of the top panels control the subsidence profile.

Numerical modelling of multistage caving processes: insights from multi‐seam longwall mining‐induced subsidence

“…Khanal et al . and Adhikary et al . have reported results of multi‐seam subsidence simulation using a FEM code developed at CSIRO called COSFLOW.…”

“…Despite many examples of single‐seam subsidence, there are only a few examples of numerical modelling of multi‐seam subsidence in the literature. In fact, to the best knowledge of the authors, the only published works with reasonable details on numerical simulation of multi‐seam subsidence is limited to the works of .…”

“…They reported reasonable prediction of enhanced multi‐seam subsidence above two mining horizons with different mining configurations, although their numerical model could not be verified with observational data as the longwall panels were yet to be extracted. In their approach, Bedding surfaces and joints are implicitly modelled by incorporating a smeared material approach (reduced strength material) based on Cosserat theory , which allows defining different bedding rigidities for individual layers; They used elastic‐perfectly plastic Mohr–Coulomb material model. Using this material, the post‐failure behaviour of the goaf cannot be simulated accurately, and Req.…”

“…Despite many examples of single-seam subsidence, there are only a few examples of numerical modelling of multi-seam subsidence in the literature. In fact, to the best knowledge of the authors, the only published works with reasonable details on numerical simulation of multi-seam subsidence is limited to the works of [2,11,18,19,34]. Suchowerska [18], Suchowerska et al [11] and Suchowerska et al [34] modelled multi-seam subsidence using various material models, such as elastic layered material, strain-softening and elastic transversely isotropic material.…”

“…These methods include finite element method (FEM) [6][7][8][9][10][11], discrete/distinct element method [12,13], finite deference method [14,15], mesh free methods and user-defined damage models [16,17]. However, there are only a few examples of numerical modelling of multi-seam subsidence available in the literature [2,11,18,19]. Numerical modelling of multi-seam subsidence is inherently more complicated than single-seam subsidence.…”