Paul, Avinash and Murthy, V. M. S. R and Prakash, Amar and Singh, Ajoy Kumar (2024) Support design in underground coal mines using modified rock mass classification system (RMRdyn) for enhanced safety– an approach from stable and failed roof cases. Environmental Earth Sciences, 83 (103). pp. 276-285. ISSN 1866-6280

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Abstract

Bord and pillar method of mining continues to be a major operation in India with about 160 mines producing 35 MT of coal. Owing to the exhaustion of near-surface deposits, environmental impacts and land acquisition issues associated with surface mining, underground coal mining is expected to take a leap in the next decade. Weak and layered roof strata in underground mining play a significant role in roof failures in development headings affecting both safety and productivity. Despite well-defined support design guidelines based on CMRI-ISM RMR, roof failures are still a cause of great concern. In this research, firstly, a risk matrix has been framed on the basis of stable and unstable roof conditions for evaluating the potentiality of roof failure. This was followed by the development of a modified Rock Mass Classification System (RMRdyn) considering Seismic velocity of rocks as one of the key parameters. A modified empirical relationship for rock load (RL) and a handy nomogram has been developed based on input parameters, namely, P-wave velocity, structural features, slake durability and groundwater condition. A guideline for roof support design has been framed based on rock load computed for RMRdyn values ranging from 25 to 70. The developed models have been validated by statistical tools. The study also presents the risk classes to enable rock engineers to design more rational support systems in coal mine development headings.

Item Type:	Article
Uncontrolled Keywords:	Risk matrix Dynamic rock mass classification system (RMRdyn) CMRI-ISM RMR Rock load Bord and pillar Roof fall height (RFH) Exposed bolt length (EBL)
Subjects:	Bord and Pillar Mining
Divisions:	UNSPECIFIED
Depositing User:	Mr. B. R. Panduranga
Date Deposited:	29 Jan 2024 05:21
Last Modified:	29 Jan 2024 05:21
URI:	http://cimfr.csircentral.net/id/eprint/2670

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