Development of modern sealing techniques for underground coal mining.

摘要

Mine seals are necessary in nearly every underground coal mine to isolate mined-out areas from the ventilation network. Many seals are already in place in active mines and more need to be constructed to keep up with the development of underground coal reserves. The recent accidents involving seal failures at Sago and Darby prompted MSHA to create and implement new regulations. These regulations require the design and construction of seals that are larger and stronger than ever before. Structural seals capable of withstanding the new required design loads are very expensive and time consuming to construct.;Three mine seal designs were investigated using several analysis tools to quantify the reactions and response of each design under MSHA defined pressure versus time waveform specifications. Comparisons of the analysis methods found that the most commonly used computer program for seal designs has been misapplied when generalized assumptions are made. The program is valid for engineered foundations which are not applicable for a majority of seal construction locations. By assuming fixed boundary conditions between the seal and surrounding rock, the most conservative design is not implemented unless it can be ensured that the end conditions are indeed fixed. Mine seal designs which depend on frictional resistance cannot be assumed to have fixed or simple supports as the true reaction lies somewhere between the two. Finite element modeling where material and frictional properties can be included is the most appropriate tool to analyze these types of seal designs. Validation of these tools was achieved through explosive testing a shock tube.;The objective of this research was to determine the applicability of the structural models currently being used for seal designs and their validity in a coal mining environment. To achieve this, frictional characteristics of a packsetter bag was determined so appropriate support conditions can be implemented. From this, a design matrix was created to specify applicable seal designs for varying coal mine conditions. The logistical and economic impact of each seal design was analyzed and recommendations are provided for modeling future seals.;KEYWORDS: Mine Seals, Coal Mining, Mine Safety, Explosions, Structural Dynamics Multimedia Elements Used: JPEG (.jpg)