Gateroad stability in a steeply pitching thick seam with a weak roof
- Bureau of Mines, Denver, CO (United States)
- Cyprus Shoshone Coal Corp., Hanna, WY (United States)
The U.S. Bureau of Mines conducted a ground pressure analysis of a wide abutment-type chain pillar in a two-entry gateroad of Cyprus Shoshone Coal Corp.`s Shoshone No. 1 Mine, which has an extremely weak immediate roof. About 50 ft of fragile mudstone, which has half the strength of the coal and behaves like unconsolidated fill, lie between the seam and the lowest competent roof member. To improve roof stability and reduce closure in tailgate entries, the operator has used three- and two-entry gateroad designs with several pillar sizes and has utilized a number of secondary support systems, with varying degrees of success. This paper discusses the layout and performance of past and current gateroad designs and the effectiveness of the various secondary support methods. The results of the pillar pressure study are compared to pillar loading predicted by Wilson`s {open_quotes}confined core pillar{close_quotes} equations. The USBM`s Analysis of Longwall Pillar Stability (ALPS) gateroad pillar design model is used to determine the stability of the headgate pillars of the most recent longwall panel. ALPS and the Coal Mine Roof Rating (CMRR) system (also USBM-developed) are used to evaluate tailgate-mining stability of the previous gateroads and to determine pillar and entry width and top coal thickness criteria for tailgate stability in future panels.
- OSTI ID:
- 171671
- Report Number(s):
- CONF-9506114--
- Country of Publication:
- United States
- Language:
- English
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