Impact of Weatherability on the Geomechanically Stability of Coal Pillars in Underground Mining
Keywords:
Bord and Pillar Mining, Roof Stability, Weathering, Rock Mass Rating (RMR), Dynamic Rock Load, Support Design, Mine Safety.Abstract
Roof stability in bord and pillar coal mines is critically influenced by the dynamic interplay of geological and operational factors. This study investigates the detrimental impact of weathering and repetitive blasting vibrations on the temporal degradation of Rock Mass Rating (RMR) and the consequent escalation of dynamic rock loads. Field investigations at operational mines were conducted to analyze these time-dependent interactions.
A modified rock load equation, incorporating time-decaying RMR, was developed. Regression analysis established empirical models correlating weathering, RMR, and increasing rock loads for standard gallery widths. The results confirm a significant temporal increase in rock load due to strength reduction from moisture, chemical weathering, and blast-induced micro-fracturing.
Conventional support systems, designed on static rock mass assumptions, are shown to be inadequate for these dynamic conditions. This research proposes integrating time-dependent factors into support design to mitigate roof fall risks. These models enable a proactive framework for stability management, facilitating timely reinforcement strategies that enhance safety and optimize resource utilization.
By addressing a primary cause of mining fatalities, this work offers actionable strategies to enhance operational safety and sustainability. The findings provide critical guidance for engineers and policymakers in developing resilient adaptive practices for underground coal mines.
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References
[1]. Bieniawski, Z.T. (1989). Engineering Rock Mass Classifications. Wiley.
[2]. Singh, B., & Goel, R.K. (2011). Engineering Rock Mass Classification. Butterworth-Heinemann.
[3]. Hao, H., Wu, C., & Zhou, Y. (2002). Numerical analysis of blast-induced stress waves in a rock mass with anisotropic continuum damage models. Rock Mechanics and Rock Engineering, 35(2), 79-94.
[4]. Edelbro, C. (2004). Evaluation of rock mass strength criteria. Doctoral dissertation, Luleå University of Technology.
[5]. Zhu, Z., Mohanty, B., & Xie, H. (2007). Numerical investigation of damage blasting induced in cylindrical rocks. International Journal of Rock Mechanics and Mining Sciences, 44(2), 283-292.
[6]. Santi, P.M. (2006). Field methods for characterizing weak rock for engineering. Environmental & Engineering Geoscience, 12(1), 1-11.
[7]. Bieniawski, Z.T. (1973). Engineering classification of jointed rock masses. Transactions of the South African Institution of Civil Engineers, 15(12), 335-344.
[8]. Kalamaras, G.S., & Bieniawski, Z.T. (1995). A rock mass strength concept for coal seams. In Proc. of the 8th ISRM Congress, Tokyo (pp. 295-302).
[9]. Kumar, R., et al. (2016). Development of ground vibration equations for blasting in surface coal mines. Journal of Rock Mechanics and Geotechnical Engineering, 8(3), 341-349.
[10]. CMRI (1987). Geo-mechanical classification of roof rocks vis-à-vis roof supports. S&T Project Report, Central Mining Research Institute, Dhanbad.
[11]. Paul, P.S., et al. (2014). Critical appraisal of the CMRI-ISM RMR for the design of coal mine roof support. The Journal of The Southern African Institute of Mining and Metallurgy, 114, 964-970.
