دانلود کتاب Proceedings - New Technology for Ground Control in Multiple-Seam Mining

Compiled by the U.S. Dept of Health and Human Services, CDC/NIOSH Office of Mine Safety and Health Research, these 2007 proceedings focus on multiple-seam mining research. Multiple-seam interactions are a major ground control hazard in many U.S. underground coal mines. The effects of multiple-seam interactions can include roof falls, rib spalling, and floor heave and can seriously disrupt mining operations and threaten the safety of miners. The National Institute for Occupational Safety and Health conducted research to develop better techniques for predicting the location and severity of multiple-seam interactions. The study focused on the two most common types of multiple-seam interactions, undermining, where stress concentrations caused by previous full extraction in an overlying seam is the main concern; and overmining, where previous full extraction in an underlying seam can result in stress concentrations and rock damage from subsidence. The most important result of the study is an equation that predicts the critical thickness of the interburden required to minimize the likelihood of a multiple-seam interaction. Content:• Front Matter • Unit of Measure Abbreviations Used in This Report • Table of Contents • Abstract 1. Multiple-Seam Mining in the United States: Background 2. Multiple-Seam Mining in the United States: Design Based on Case Histories 3. LaModel: A Boundary-Element Program for Coal Mine Design 4.The New Two-Dimensional LaModel Program (LaM2D) 5. Multiple-Seam Longwall Mining in the United States: Lessons for Ground Control 6. Extreme Multiple-Seam Mining in the Central Appalachian Coalfields 7. Multiple-Seam Mining Interactions: Case Histories from the Harris No. 1 Mine 8. Failure Mechanics of Multiple-Seam Mining Interactions