Seismic tomography to image coal structure stress distribution.
Westman EC; Friedel MJ; Williams EM; Jackson MJ
Proceedings: Mechanics and Mitigation of Violent Failure in Coal and Hard-Rock Mines. Washington, DC: U.S. Bureau of Mines, 1995 May; :105-117
Stress anomalies in the vicinity of the longwall face in an underground coal mine can result in violent coal bumps, compromising the safety and efficiency of mine workers. The U.S. Bureau of Mines (USBM) is using seismic tomography to monitor distribution and relative magnitude of stress concentrations throughout a coal pillar or panel. Researchers with the USBM have performed tomographic imaging in pillars and panels of Western underground longwall coal mines in support of the continuing goal of improving safety for and efficiency of underground miners.' Results of three case studies are presented. In the first case study, tomographic images of yield pillars adjacent to a mined panel were calculated. At one site, surveys were completed on subsequent days, resulting in determinations of stress redistribution as the face retreated to within 20 m (65 It) of the pillar. In the second case study, the results of two surveys across the longwall panel as the forward abutment stress moved into the study area are described. The velocity results were compared to stress levels measured with borehole pressure cells. The final case study reports results of a survey in which a longwall shearer was used as the seismic source, rather than the hammer used in the first two studies.
Mining-industry; Coal-mining; Rock-falls; Rock-bursts; Rock-mechanics; Underground-mining; Control-technology; Geology; Geophysics; Engineering-controls; Ground-control; Ground-stability
Book or book chapter
Maleki H; Wopat PF; Repsher RC; Tuchman RJ
Proceedings: Mechanics and Mitigation of Violent Failure in Coal and Hard-Rock Mines