Effect of foundation rigidity on stratified roadway roof stability in underground coal mines
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ORIGINAL PAPER
Effect of foundation rigidity on stratified roadway roof stability in underground coal mines Lishuai Jiang 1,2 & Hani S. Mitri 2,3 & Nianjie Ma 1 & Xidong Zhao 1
Received: 5 May 2015 / Accepted: 10 September 2015 / Published online: 10 December 2015 # Saudi Society for Geosciences 2015
Abstract The stability of roadway roof has been a longstanding issue in underground coal mines and thus has received a great deal of attention by both researchers and practitioners over the past few decades. This paper presents a simple analytical model for stratified roadway roof stability analysis. The model treats the immediate roof stratum of the roadway as an elastic beam resting on Winkler-type foundation and subjected to uniform roof loading that is determined from the lithology and depth of overlying strata. The developed model calculates bending stresses and deflections of the roof beam. Two case studies from an underground coal mine are used to demonstrate the model. A model parametric study reveals that the coal foundation elasticity plays a key factor in roof deformation and potential failure. Field monitoring data is used to validate analytical model results, and the comparison shows a good agreement.
Keywords Roof stability . Coal mine roadways . Elastic foundation . Analytical solution . Rock bolt support
* Lishuai Jiang [email protected] 1
Faculty of Resources and Safety Engineering, China University of Mining and Technology, Beijing 100083, China
2
Department of Mining and Materials Engineering, McGill University, Montreal H3A 2A7, QC, Canada
3
School of Civil Engineering, Henan Polytechnic University, Jiaozuo 454000, China
Introduction Roof stability in roadways is a long-standing issue in many underground coal mines. Tens of thousands of kilometers of roadways are excavated in underground coal mines in China every year. Failure or instability of the roof can cause fatality, injury, and significant economic loss (Shen et al. 2008). Although roof failure-related fatalities and injuries in Chinese coal mines have been remarkably reduced thanks to intensive research efforts and improved industry practice, roof deformations leading to failure is still a major concern in underground coal mines. Roof stability and failure mechanisms of roadways vary depending on stress and geological and geotechnical conditions in the coal mine (Shen 2014). Due to the sedimentary nature of coal-forming process, the overlying rock mass above the coal seam exhibits a geologically stratified structure (Bakun-Mazor et al. 2009). For stratified rock roof, excessive beam bending of the immediate roof stratum is the most common cause for failure. Bed separation and delamination initiate failure of the roof and make it behave like individual beams, which may fail or break at mid-span (Zhang and Peng 2002). Numerous analytical studies have been previously developed with beam bending theory to investigate roof stability in roadways. Bakun-Mazor et al. (2009) assessed the stability of the immediate roof by invoking a continu
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