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Estimation of Rock Load in Development Workings of Underground Coal Mines – A Modified RMR Approach


Affiliations
1 Central Institute of Mining and Fuel Research, Dhanbad 826 015, India
2 Department of Mining Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad 826 004, India
 

Underground coal mining in India contributes to a share of 55 Mt production with more than 500 mines in operation. In spite of using the well-established CMRI-ISM Rock Mass Rating (RMRdyn) classification system for roof support design successfully in Indian geo-mining conditions, accidents due to roof fall constitute the major challenge. These failures are generally due to the presence of weak beddings and laminations. Seismic refraction technique (for shallow depth) can be useful in detecting the rock mass conditions. Based on the study a modified rock mass classification system (RMRdyn) was setup by incorporating field P-wave velocity with a view to arrive at a real ground condition of the in situ rock. Rock loads were also determined in the field to develop a relation with RMRdyn. A comparison of rock load estimation by CMRI-ISM RMR, numerical simulation and RMRdyn clearly depicts that the latter approach is more reliable as the results are close to the actual scenario.

Keywords

CMRI-ISM RMR, RMRdyn, P-Wave Velocity, Rock Load, Support Design.
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  • Estimation of Rock Load in Development Workings of Underground Coal Mines – A Modified RMR Approach

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Authors

Avinash Paul
Central Institute of Mining and Fuel Research, Dhanbad 826 015, India
Vemavarapu Mallika Sita Ramachandra Murthy
Department of Mining Engineering, Indian Institute of Technology (Indian School of Mines), Dhanbad 826 004, India
Amar Prakash
Central Institute of Mining and Fuel Research, Dhanbad 826 015, India
Ajoy Kumar Singh
Central Institute of Mining and Fuel Research, Dhanbad 826 015, India

Abstract


Underground coal mining in India contributes to a share of 55 Mt production with more than 500 mines in operation. In spite of using the well-established CMRI-ISM Rock Mass Rating (RMRdyn) classification system for roof support design successfully in Indian geo-mining conditions, accidents due to roof fall constitute the major challenge. These failures are generally due to the presence of weak beddings and laminations. Seismic refraction technique (for shallow depth) can be useful in detecting the rock mass conditions. Based on the study a modified rock mass classification system (RMRdyn) was setup by incorporating field P-wave velocity with a view to arrive at a real ground condition of the in situ rock. Rock loads were also determined in the field to develop a relation with RMRdyn. A comparison of rock load estimation by CMRI-ISM RMR, numerical simulation and RMRdyn clearly depicts that the latter approach is more reliable as the results are close to the actual scenario.

Keywords


CMRI-ISM RMR, RMRdyn, P-Wave Velocity, Rock Load, Support Design.

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DOI: https://doi.org/10.18520/cs%2Fv114%2Fi10%2F2167-2174