Kolikipogu, Nageswara Rao and Mandal, Prabhat K. and Das, Arka Jyoti and Jagapthal, Vinod Kumar and Bhattacharjee , R. and Tewari, S. (2025) Analysis on the Influence of Kettlebottoms in Underground Coal Mines: A Study Using Numerical Modelling and Limit Equilibrium Method. Rock Mechanics and Rock Engineering , 58. pp. 13483-13501. ISSN 0723-2632

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Abstract

Kettlebottoms are geological discontinuities that can significantly impact the stability of underground mine workings by disrupting the continuity of rock masses. The safety implications of kettlebottoms are widely debated in Indian and global coal mining industries. The research on kettlebottoms has primarily focused on their origin and stratigraphy; however, only a few studies have utilized numerical modelling techniques to assess their impact on surrounding areas of underground workings. To address the research gap, this paper presents a comprehensive study using numerical modelling and the Limit Equilibrium Method (LEM) to analyse the impact of kettlebottoms on underground coal mine workings, considering the specific geo-mining conditions of the 3&4 incline mine at Eastern Coal Fields Limited (ECL), India. The mine consisted of numerous geological discontinuities, with kettlebottoms being a significant concern among them. The numerical modelling with FLAC3D offered insights into mining-induced stresses and failure of roof rocks around the kettlebottom zone. The results indicated that the influence of each kettlebottom along the mine roadways was twice its base diameter. The impact of kettlebottoms on the adjacent strata intensifies as soon as they separate from the roof. A notable finding discloses a ‘stress concentration zone’ in overlying strata just above kettlebottoms, and the rock load (an important parameter used in designing support systems) developed over galleries and junctions of roadways was 70% higher than non-kettlebottom zone. Further, the stability of kettlebottoms was assessed by Factor of Safety (FoS) derived from the Limit Equilibrium Method. This analytical equation additionally corroborated the modelling results. Considering the detrimental effect of kettlebottoms on the surrounding strata, a new support design utilizing roof bolts with W-straps was proposed and implemented at the 3&4 incline mine of ECL, India. The observations from the 3&4 incline mine indicated that the roadways are in excellent condition with the optimum support design. The findings of this study provide a quantitative analysis of roof stresses and plastic zone distribution around kettlebottoms in underground coal mine workings.

Item Type:	Article
Subjects:	Thick Seam Mining
Divisions:	UNSPECIFIED
Depositing User:	Mr. B. R. Panduranga
Date Deposited:	20 Jan 2026 09:33
Last Modified:	20 Jan 2026 09:33
URI:	https://cimfr.csircentral.net/id/eprint/2914

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