In longwall mining, there are some important issues that must be examined to ensure undisturbed progress of mineral extraction. Among these is the need to evaluate the maximum load expected on the longwall shields. To address this problem, a study was undertaken to examine the process of fracturing of the immediate and main roof strata behind the longwall face. The finite difference element code FLAC2D, developed by Itasca Consulting Group, Inc. was used to perform modeling of the longwall gob area under both soft and hard roof. The purpose of this paper is to present the applicability of a numerical modeling technique to investigate the performance of mine roof strata following the advancing longwall face. The study was made for both hard and soft roof while keeping the floor strength constant. The results obtained from both studies have been compared in order to better understand the load on the shields.
1. INTRODUCTION
In longwall mining, there are some important issues that must be examined to ensure undisturbed progress of mineral extraction. Among these is the need to evaluate the maximum load expected on longwall shields. To address this problem, a study was undertaken to examine the process of fracturing of the roof strata that follows the longwall advancement.
Many factors influence support weighting [1], the most important of which include:
seam thickness
bulking characteristics of immediate roof
cover depth and abutment stress
strength and stiffness of immediate roof members
jointing in immediate roof
cleat density in coal.
