Calculation of periodic roof weighting interval in longwall mining using finite element method
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ORIGINAL PAPER
Calculation of periodic roof weighting interval in longwall mining using finite element method Navid Hosseini & Kamran Goshtasbi & Behdeen Oraee-Mirzamani & Mehran Gholinejad
Received: 27 October 2011 / Accepted: 25 January 2013 # Saudi Society for Geosciences 2013
Abstract The state of periodic loading and the interval of periodic roof weighting have an important role in geomechanical stability and, hence, in the continuity of longwall mining operations. In this paper, the mechanism of roof caving in longwall mining—together with the effect of engineering and geomechanical properties of surrounding rock masses on the magnitude and timing of periodic loading—is studied. For this purpose, a longwall mine is first modeled using Phase2 software, and then, by simulating the roof caving process, the periodic roof weighting intervals is calculated. Based on the numerical modeling, the first roof weighting interval and the periodic roof weighting interval are calculated as 27.2 and 12.1 m, respectively. Sensitivity analysis is then applied to determine the effect of changes in the mechanical properties of the rock mass, especially in the main roof and immediate roof. The results of the analysis show that as GSI and quality of the immediate roof increases, the periodic roof weighting interval also increases. Hence, the applied algorithm in this research study can effectively be utilized to calculate the periodic roof weighting interval in the longwall mining method. Keywords Longwall mining . Periodic roof weighting interval . Finite element method . Phase2 software N. Hosseini (*) : M. Gholinejad Department of Mining Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran e-mail: [email protected] K. Goshtasbi Department of Mining Engineering, Tarbiat Modares University, Tehran, Iran B. Oraee-Mirzamani Centre for Environmental Policy, Imperial College London, London, UK
Introduction The process of periodic loading in longwall mining is complex and significantly influences safety, stability, performance, and the productivity of mining operations (Singh and Singh 2010). Periodic loading and the periodic roof weighting interval are related to geomechanical conditions of the surrounding rock mass, particularly to the immediate roof (Peng 2006). Roof caving mechanism and the rate of advance represent additional influences on the state of periodic loading. The roof weighting interval increases due to a delay in caving (or un-caving) of the roof and a great deal of subsequent pressure on the power support system, which affects the mining operation (Peng 2008). Therefore, it is necessary to study the process of periodic loading in longwall mining, especially in a mechanization mining operation. Up until now, several studies have been carried out to determine the status of periodic loading, first roof weighting interval, periodic roof weighting interval, and various equations have been derived (Peng 2006; Peng 2008; Jeremic 1985; Trueman et al. 2009; Monjezi et al. 2011). However, due to thei
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