Resistance Of Artificial Mine-Roof Support

THE purpose of this paper is to make public record of new information in regard to the sustaining power of artificial mine-roof supports (not timber props) the result of investigations recently made in the anthracite coal fields of Pennsylvania. First.-By the "Scranton Mine Cave Commission," appointed to investigate the mining conditions under the City of Scranton. Second.-By the "Pennsylvania Mine Cave Commission," appointed by the Governor to investigate the general subject of mine caves in the anthracite region of Pennsylvania. Third.-By the personal researches and tests made by the author in an effort to secure a better artificial mine-roof or surface support. During the progress of the work of the Scranton Mine Cave Commission, the Engineers for the Commission, Messrs. Conner and. Griffith, being aware of the general lack of exact information in the engineering profession as to the strength of the ordinary artificial mine-roof or surface support, and particularly the stronger kinds, such as mine cogs, rock piers, etc., had tests made at the. Fritz Engineering Laboratory at Lehigh University, to determine the sustaining power under various compressions of the several kinds of artificial mine supports in use in the anthracite region of Pennsylvania. A report of these tests was included in the report of this Commission, which was published as Bulletin No. 25 of the United States Bureau of Mines, Washington. A similar series of tests, more extensive and more elaborately-planned, were subsequently made for the Pennsylvania Mine Cave Commission at the U. S. Government Testing Laboratory at Pittsburgh, Pa. The report of this Commission was made to the Governor, but has not yet been published.