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SME-ICGCM (1801)
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TITLE Horizontal Stresses and Their Impact on Roof Stability at the Nelms No. 2 Mine
SUMMARY This paper is not available for inclusion in the Proceedings at the time of printing, but it will be included as an insert.
AUTHOR Lizak, J. B.
TITLE Impact Of Horizontal Load On Shield Supports
SUMMARY A theoretical evaluation of the impact of horizontal load on shield support capacity is made from a static rigid body analysis of the shield structure. Parameters affecting horizontal support resistance are investigated for a typical too-leg shield design. Horizontal forces acting on a roof support element are found to be both roof-generated and shield-generated. The impact of shield-generated horizontal forces on roof strata is also discussed from a theoretical viewpoint in relation to desired ...
AUTHOR Barczak, Thomas M.
TITLE Yield Pillar Applications--Impact On Strata Control And Coal Production
SUMMARY This paper is not available for inclusion in the Proceedings at the time of printing, but it will be included as an insert.
AUTHOR Martin, E.
TITLE Expanded Cement: New Solutions for Age-Old Problems
SUMMARY The development of an expanded cement product represents a major advance in the technology of roof control systems. Such a product is gaining recognition as a valuable tool in today's cost- conscious coal mines. The National Coal Board's Bretby Research Lab, in conjunction with Polement Ltd., developed the first lightweight cement for use in the mines of the United Kingdom. The product, Aqualight, is a low-density (about 12.5 PCF) cement with a typical compressive strength of about 19 p.s.i. The...
AUTHOR Wood, John K.
TITLE Design Of A Roof Truss Bolting Plan For Bear Mine
SUMMARY Between June of 1975 and November of 1978 Stateham and Radcliffe of the Denver Research Center of the Bureau of Mines in cooperation with officials of the Bear Coal Company of Somerset. Colorado Conducted extensive studies of the roof conditions in the Bear Mine. The purpose of the investigation was to determine the relationship if any between the length of time the roof was left unbolted and the subsequent stability of the roof. Using the comprehensive information available from Stateham and Ra...
AUTHOR Mangelsdorf, C. P.
TITLE Determination of Effective Column Lengths for Resin-Grouted Roof Bolts
SUMMARY The use of resin-grouted rock anchors continues to gain popularity in underground wall mines in the United States. It is estimated that during 1985, more than 30% and as many as 35% of all roof bolts used employed sane from of resin anchor. The so-called 'combination' bolting systems, which generally utilize a resin pint-anchor, have also found increased application. This increased application is particularly true in poor ground, where more 'traditional' support measures have performed poorly. V...
AUTHOR Cincilla, W. A.
TITLE Massive Pillar Failure--Two Case Studies
SUMMARY Similar massive pillar failures were observed in two underground coal mines with different configurations of mine workings and overburden depths. Finite element models were used to analyze the causes and mechanisms of the pillar failure. The results of the analyses confirms the underground observation. For Case No. 1 the failure of coal pillar is mainly caused by a combined effect of smaller coal pillars under a large overburden and the interaction of multiple seam mining. For Case No. 2, the pi...
AUTHOR Tang, David H.
TITLE Clay Veins: Their Physical Characteristics. Prediction, and Support
SUMMARY Clay veins, also referred to as clay elastic dikes, have been responsible for numerous underground injuries and fatalities. These hazardous structures are also responsible for increased production costs during all phases of mining. For these reasons, the Bureau of Nines has investigated the physical characteristics of and roof instability problems associated with clay veins in order to make support and other mining recommendations. In addition the occurrence and origins of clay veins were examin...
AUTHOR Chase, Frank E.
TITLE A Novel System For Automatic Installation Of Cement Grouted Roof Bolts
SUMMARY BETTER ROOF SUPPORT During the last decade, resin-grouted roof bolts have taken a substantial foothold in the coal mining industry - now accounting for about one-third of all bolts installed annually, due to the improved roof support. However, the high cost, toxicity and flammability of the resin cartridges appear to be a limiting factor in even greater use of such bolts. Terra Tek, Inc. has, over the past few years, been developing a novel roof bolting system to mix/inject a very fast-settin...
AUTHOR Mahyera, A.
TITLE First Caving And Its Effects--A Case Study
SUMMARY In late September 1984, a longwall panel in West Virginia lost 60 powered supports when the face had advanced for 250 ft. from the setup entry. An in-mine investigation showed that it was a first weighting failure resulting from inadequate Support capacity. This paper presents the results of finite element modeling, which have led to a better understanding of the first weighting failure mechanism. The dynamic impact of the first weighting failure on the powered supports is analyzed. The optimum ...
AUTHOR Hsiung, S. M.