Hamid Maleki, PhD, PE
Maleki Technologies, Inc. (MTI)
Abstract:
Review of Coal Burst Mechanics and Control Measures in Three Major United States Coal Fields
This presentation reviews a study conducted by MTI for ACARP to assist Angelo-American operations with better understanding of coal burst mechanics and control based on U.S. practical experience, investigations, and inspections in three major U.S. Coal Fields over the past five decades. The study examined both nonviolent and burst prone case studies to identify contributing risk factors and addressed failure mechanisms for major US coal fields in Utah, Colorado, and Kentucky, which have diverse characteristics.
To investigate the mechanics of coal burst, we have used a multi-pronged approach. First, field measurements in three mines from East Mountain, Utah, are complemented with finite-difference stress analyses to address the importance of horizontal stress in coal pillar mechanics of violent failure. Second, we have reviewed computational procedures for estimating seismicity resulting from slip along geological discontinuities, as these measurements point to seismicity being the trigger mechanism for violent failure of marginally stable structures. This joint-slip seismicity mechanism agrees with the more recent improved re-examination of MIS data from the Crandall Canyon Mine, Utah by University of Utah Third, we have applied a hybrid statistical-analytical methodology for identifying significant factors affecting coal burst. It utilizes data from 30 case studies including those from Utah, Colorado, Kentucky, and other Eastern U.S. mines providing predictive capability for the entire United States coal fields . The statistical method reinforces comprehensive field measurements from Utah/Kentucky mines and points to strata rigidity, joint spacings and horizontal stress field as significant factors affecting damage resulting from coal bursts. This provides practical capabilities for identifying operations of higher risk using a rigidity-cavability variable.
Overall, the study provides valuable insights into the mechanics and risk factors associated with coal bursts in major U.S. coal fields. By utilizing a multi-pronged approach that incorporates both field measurements and statistical- analytical calculations, the study offers practical capabilities for identifying operations of higher risk and improving coal burst control.
Bio:
Hamid received graduate degrees from the Colorado School of Mines while working at SUFCO mine implementing an extensive instrumentation program for quantifying cave conditions, strata cantilevering, excessive deformation and roof stability problems and predictive methods, 1981. He undertook additional training in Civil Engineering, hydrology and numerical modeling 1992-1994. Hamid has forty five years of worldwide experience in mine design, geotechnical monitoring, stress analyses/rock burst control, permitting and mine safety/ ground control training (250 major projects) and has 110 technical publications. He is a recipient of Society of Mining Engineers (SME’s) Rock Mechanics Award, 2015 and was a keynote U.S. speaker on the subject of Rock Burst Mechanics and Control, Hunter Valley, Australia 2019. Between 1991-1995, as the technical advisor for the USBM, Spokane Research Center, Hamid implemented several extensive geophysical (tomographic) and static measurement programs in U.S. mines, developing techniques for assessing changes in roof, floor and pillar stability and improving mine safety. He was the editor for the USBM Special Publication, Mechanics and Mitigation of Violent Failure, 1995. The report was presented in three U.S. coal and hard rock mining districts and is still being used in Australia.