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Design of rock bolt-based goaf edge support for conventional depillaring with stowing

Abstract

Rock bolts have replaced the conventional cog/chock as roof support from underground coal mines working with continuous miner (CM) technology in Bord and Pillar mining method with caving system. Rock bolts installed in the gallery at the goaf edge by aligning the adjacent stable rib during the CM-based mechanised depillaring have proven its potential by restricting goaf encroachment towards the working area. However, conventional depillaring with stowing and caving system still uses skin-to-skincog/chock as goaf edge support in Indian coalfields which poses threat to the safety of miners during its erection and withdrawal. Further, bearing capacity of such goaf edge support also reduces with increase in height of working. Field study found that the adjacent in-bye rib of the working slice remains intact and stable due to less span of hanging roof inside the goaf during conventional depillaring with stowing compared to caving. These field outcomes are also validated during the numerical simulation and observed that the goaf edges are over-supported in a stowing panel as it adopted the similar goaf edge support pattern as that of caving. Further, a parametric study is conducted on numerical models by varying the nature of roof, gallery width, and depth of cover to estimate the rock load height (considering 1.5 safety factor contour) around the goaf edges in stowing panels. Multivariate regression analysis was carried out to establish a relationship among influencing parameters for estimation of rock load height at the goaf edges in stowing panels for a given geo-mining condition. This paper presents a novel design of rock bolts as goaf edge support on the basis of roof-rib interaction in conventional depillaring with stowing panel.

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Acknowledgements

The authors are obliged to Director of CSIR-CIMFR Dhanbad and Director of NIT Rourkela, for their permission to publish this paper. The cooperation provided by the management of different mines of Satgram Area of Eastern Coalfield Limited (ECL) during the field visit is thankfully acknowledged. The study reported in this paper is based on an investigation done under sponsored projects, funded by ECL. The views expressed in the paper are those of the authors, and not necessarily of the institute to which they belong.

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Correspondence to Sahendra Ram.

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Responsible editor: Murat Karakus

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Ram, S., Singh, A.K., Kumar, R. et al. Design of rock bolt-based goaf edge support for conventional depillaring with stowing. Arab J Geosci 14, 2164 (2021). https://doi.org/10.1007/s12517-021-08379-3

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Keywords

  • Rock bolt
  • Conventional depillaring
  • Stowing
  • Caving
  • Numerical modelling
  • Rock load height
  • Goaf edge support