Verification of 3D Numerical Modeling Approach for Longwall Mines with a Case Study Mine from the Northern Appalachian C
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Verification of 3D Numerical Modeling Approach for Longwall Mines with a Case Study Mine from the Northern Appalachian Coal Fields Deniz Tuncay 1
&
Ihsan Berk Tulu 1 & Ted Klemetti 2
Received: 25 May 2020 / Accepted: 15 September 2020 # This is a U.S. government work and its text is not subject to copyright protection in the United States; however, its text may be subject to foreign copyright protection 2020
Abstract Accurately estimating load distributions and ground responses around underground openings plays a significant role in the safety of the operations in underground mines. Adequately designing pillars and other support measures relies highly on the accurate assessment of the mining-induced loads, as well as the load-bearing capacities of the supports. There are various methods that can be used to approximate mining-induced loads in stratified rock masses, both empirical and numerical. In this study, the numerical modeling approach recently developed at West Virginia University, which is based on the modeling approach developed by the National Institute for Occupational Safety and Health (NIOSH), is investigated using the finite difference software FLAC3D. The model includes the longwall panels, the adjacent chain pillar systems, and the different stratigraphic layers of the overburden. Using the 3D model, changes in loading conditions and deformations on the areas of interest, induced by an approaching longwall face, can be examined. This paper details the 3D modeling of a longwall panel utilizing this approach, and the verification of the results against field observations. The studied panel was 360 m wide with a 3-entry chain pillar system and about a 160-m average overburden depth around the studied area. The overburden strata consist of alternating layers of shale, sandstone, and limestone. The FLAC3D results were compared against field measurements from the mine site. The stress change values measured in the chain pillars were comparable with the modeling results. The model also replicated the surface subsidence profile obtained from field measurements fairly well. Overall, the 3D modeling approach was found to be successful for the case study longwall panel. Keywords Coal mining . Longwall mining . Finite volume model . Flac3D . Northern Appalachian
1 Introduction Accurately estimating mining-induced load distribution and resulting ground response in underground mines plays a significant role in pillar and ground support design, hence in the safety of mining operations. There are different methods, both empirical and numerical, that can be used to assess load transfer that takes place during panel retreat. In cases where more complex stress changes are expected, calibrated numerical models can be used [1]. The numerical models are based on fundamental laws of
physics and approximate the geo-mechanical behavior of the coal and overburden. Since geologic material rarely follows theoretical behavior, models must be carefully calibrated, and model outputs are as reliable as the reliability of mode
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