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Pillar Design for Longwall Mining Based on Field Measurements.

Paper C6 in Proc 8th Int'l Strata Control Conf Steinkohlenbergbauverein Essen Germany '89 :20 pages
Effective ground control in the gate entries is essential to safe multientry longwall mining as practiced in the United States. Longwall pillars are responsible for maintaining gate entry stability and for carrying abutment loads. Recent research conducted by the Bureau of Mines and others has led to the development of a new method for designing longwall pillars, called analysis of longwall pillar stability (alps). The alps method is based on field studies that were conducted in five mines in four states. In each study, multiple stressmeters were installed in longwall pillars and monitored during mining. The stress histories obtained from the measurements provided empirical parameters for making design estimates of the abutment loads. The field measurements also showed that available empirical pillar strength formulae could be used in alps for longwall pillar design. The alps method has been verified by back-analysis of nearly 100 mining case histories from longwalls located throughout the eastern United States. It is particularly useful for preliminary longwall pillar design and it also provides a framework for optimizing pillar size based on site-specific experience.
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OP 92-91
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Paper C6 in Proc. 8th Int'l Strata Control Conf. Steinkohlenbergbauverein, Essen, Germany, '89