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Investigations of differential strata movements and water table fluctuations during longwall operations at the Somerset Mine No. 60.

Barla GB; Bashkov S

Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, Contract - G-9041, 1978 Jan; :1-149

10003678

This research work was directed toward the acquisition of data describing the phenomenology of failure of superincumbent strata during longwall mining operations in the Pittsburgh coal seam. The specific site for the study was the second panel in the Somerset Mine No. 60, belonging to the Bethlehem Steel Company, and located near Washington, Pennsylvania. The thickness of the coal approximated 68 inches. Two boreholes were instrumented as strata movement monitoring stations, drilled from the surface to the coal seam, which was located under 330 feet to 430 feet of cover. Five additional holes were drilled to an approximate depth of 150 feet in order to permit observations on the water table fluctuations. Cores recovered from the two instrumented boreholes were geomechanically logged throughout. The recorded data indicate that strata behavior differs in locations close to the first break from those which follow the establishment of regular caving. The fracture of impermeable layers inevitably leads to sudden drops in the water table. The data suggest the existence of a very steep angle of fracture growth coupled to an immediate propagation upward for the caved area.

Longwall mining; Strata movement; Coal mining; Experimental data; Extensometers; Geology; Ground subsidence; Ground water; Level indicators; Monitoring; Tables; Underground mining

19780101

CP; Final Contract Report

1978

FE90411

A08

Contract - G-9041

PRC

Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, Contract - G-9041

PA; NY; TN

Columbia University, New York