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Clay Veins: Their Physical Characteristics. Prediction, and Support.
Proc 4th Conf on Ground Control in Mining 1985 Jul; :212-219
Clay veins, also referred to as clay or clastic 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 U.S. Bureau of Mines has investigated the physical characterisitics 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 examined to determine whether or not the structures could be projected into unmined portions of the coalbed. This investigation included portions of the Arkoma, Illinois, northern Appalachian, southern Appalachian, and Warrior Coal Basins. Virtually all clay veins observed or documented occurred in the Illinois and Northern Appalachian Basins. Observed clay veins ranged from 1 in to 16 ft in cross section and were found under shale, siltstone, sandstone, and limestone roof rock. Individual clay veins were predominantly composed of claystone; however, limestone, siltstone, and sandstone infilled clay veins do occur. Clay vein formation has been associated with the infilling of fissures which result from compressive, tensile, or shear ground failures. These gaping fissures were propagated by compactional processes and/or tectonic stresses active during and subsequent to coalification. Associated fault, fracture, and slickenside planes commonly parallel clay veins and disrupt the lateral continuity of the immediate and, sometimes, main roof. When clay veins parallel or su
Proc. 4th Conf. on Ground Control in Mining, July 22-24, 1985. WVU Univ., 1985, PP. 212-219
Page last reviewed: March 11, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division