Date of Graduation

2004

Document Type

Thesis

Degree Type

MS

Committee Chair

Keith A. Heasley

Abstract

In this thesis, the need for a fast and easy to use numerical analysis program for calculating multiple seam interactions is established. To fulfill this, a simplified twodimensional (2D) laminated overburden model was mathematically developed. Also the utility of the 2D laminated model for modeling complex multiple-seam interaction was further enhanced by its ability to calculate the pillar safety factors and multiple-seam induced subsidence and strain. The 2D laminated overburden model is then implemented into a displacementdiscontinuity program called LaM2D. The LaM2D program can be used to calculate seam convergence, vertical stress, multiple seam stress, pillar safety factors, subsidence and horizontal strain in flat-lying seams. The LaM2D program was then checked for computer coding errors and mathematical accuracy. After the mathematical accuracy of the LaM2D program had been checked, a comparative case study was performed using the full-featured 3D LAMODEL program and the simplified 2D LaM2D program. The comparative case study is an analysis of a longwall panel undermining an active room-and-pillar main line development. In this comparative case study, the total parameter input and solution of the model for the simplified LaM2D program was less than 10 minutes. In addition, the vertical stress calculated by both the LAMODEL and the LaM2D programs were the same and the stress values calculated for the modeled cross-section was consistent with observations reported in the field. Furthermore, LaM2D

went a step further to calculate the overlying room-and-pillar mines’ pillar safety factor, subsidence and the horizontal strain caused by the mined longwall panel. In the conclusion of this thesis, it was suggested that the simplified LaM2D program allows the user to quickly and easily calculate the stresses, displacements, safety factors and strains associated with basic multiple-seam mining situations that can be accurately represented in two dimensions. This program can be a very useful tool for structural planning and analysis of complex multiple-seam conditions.

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