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Prediction of Rock Load Emphasizing Excavation Damage of in situ Rocks Caused by Blasting in Coal Mines


Affiliations
1 CSIR-Central Institute of Mining and Fuel Research, Dhanbad 826 015, India
2 Department of Mining Engineering, IIT Indian School of Mines, Dhanbad 826 004, India
3 Formerly at CSIR-Central Institute of Mining and Fuel Research, Dhanbad 826 015, India
 

Roof failure in coal mines is strongly related to the frequency of laminations and their movement when the load acts upon them. Detachment of roof bolts from mine roof due to improper estimation of extent of weak zone is one of the major problems in underground coal mines, thus affecting the safety and productivity of workings. The most popular and practised method for roof support design in Indian coal mines is the Central Mining Research Institute-ISM geomechanical classification system. Irrespective of such an established system of support design, accidents due to roof fall still persist. Here we review various available classification systems for rock load estimation and identify their limitations. The study has been extended taking into consideration the case study of KTK-6 incline of Singareni Collieries Company Limited by proposing a modified rock mass classification system based on seismic wave velocity as a key descriptor. A modified rock mass rating (RMR) system (RMRdyn) with inclusion of seismic velocity as one of the parameters is proposed for the estimation of rock load. Enhancement in rock load by 20% has been found for RMRCMRI-ISM values less than 40 according to the new rock load relation. This resulted in under-supporting of the roof and thus might have caused failures. For cases with RMRCMRI-ISM values more than 60, the earlier equation overestimates rock load by about 25% resulting in over-supporting. Thus, estimation of rock load from the proposed new equation appears to be more rational as it takes into account the actual damage zone.

Keywords

Blasting, Coal Mines, Excavation Damage, Rock Load.
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  • Prediction of Rock Load Emphasizing Excavation Damage of in situ Rocks Caused by Blasting in Coal Mines

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Authors

Avinash Paul
CSIR-Central Institute of Mining and Fuel Research, Dhanbad 826 015, India
Vemavarapu Mallika Sita Ramachandra Murty
Department of Mining Engineering, IIT Indian School of Mines, Dhanbad 826 004, India
Amar Prakash
CSIR-Central Institute of Mining and Fuel Research, Dhanbad 826 015, India
Ajoy Kumar Singh
Formerly at CSIR-Central Institute of Mining and Fuel Research, Dhanbad 826 015, India

Abstract


Roof failure in coal mines is strongly related to the frequency of laminations and their movement when the load acts upon them. Detachment of roof bolts from mine roof due to improper estimation of extent of weak zone is one of the major problems in underground coal mines, thus affecting the safety and productivity of workings. The most popular and practised method for roof support design in Indian coal mines is the Central Mining Research Institute-ISM geomechanical classification system. Irrespective of such an established system of support design, accidents due to roof fall still persist. Here we review various available classification systems for rock load estimation and identify their limitations. The study has been extended taking into consideration the case study of KTK-6 incline of Singareni Collieries Company Limited by proposing a modified rock mass classification system based on seismic wave velocity as a key descriptor. A modified rock mass rating (RMR) system (RMRdyn) with inclusion of seismic velocity as one of the parameters is proposed for the estimation of rock load. Enhancement in rock load by 20% has been found for RMRCMRI-ISM values less than 40 according to the new rock load relation. This resulted in under-supporting of the roof and thus might have caused failures. For cases with RMRCMRI-ISM values more than 60, the earlier equation overestimates rock load by about 25% resulting in over-supporting. Thus, estimation of rock load from the proposed new equation appears to be more rational as it takes into account the actual damage zone.

Keywords


Blasting, Coal Mines, Excavation Damage, Rock Load.

References





DOI: https://doi.org/10.18520/cs%2Fv118%2Fi1%2F123-132