Sumant Mohanto, Debasis Deb, Amrites Senapati

Abstract: The role of crown pillar between two main levels in any underground metalliferrous mine plays a crucial role in maintaining the stability of the extracted open stopes. Thus, the dimension of the crown pillar left intact between the main levels in the underground should be competent enough to withstand the induced stresses developed as a result of extraction as well as blasting, especially in large scale production methods such as large-diameter blasthole stoping method. In addition to the crown pillars in adjacent levels, a barrier crown pillar of sufficient thickness is also left intact between the ultimate pit bottom and the first level of extraction. These horizontal pillars are of utmost importance as it is one of the deciding factors in determining the stability of the existing underground structures throughout the life of mine. The present study focuses on the stability of a crown pillar left intact between two main levels existing below an open pit mine operating simultaneously with the underground mine. The targeted proposed production of the underground mine is around 5 million tonne per annum. In this paper, 135 finite element simulation models of the underground mine have been analyzed considering elasto-plastic material model. The simulation models are evaluated in terms of plastic damage index with variation in rock mass properties, thickness of crown pillar, stope-extraction sequence and mining depth. Based on the results obtained, some useful conclusions have been drawn considering multi-variate regression and k-cross validation models.

Keywords: Crown pillar ⋅ Underground structures ⋅ Plastic damage index ⋅ Multi-variate regression ⋅ k-fold cross validation.

Date Published: July 2, 2024
DOI: 10.11159/ijci.2024.008

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