ABSTRACT

ABSTRACT: Though great progress has been made in application of rock mechanics principles in the past few decades, ground instability is still among the major causes of serious incidents and production disruptions in underground mining. There exists substantial literature that investigates various aspects of ground instability using analytical and numerical methods. There are also studies concentrating on statistical analysis of recorded ground failure incidents. However, there has been a lack of insight into the ground failure mechanism based on mining cases and observations with safety significance, and inadequate guidance on improvement of mining systems or processes to reduce ground instability incidents in underground mining. This paper presents selected ground failure cases from ten underground metal mines located in five countries. These cases are all serious incidents with detailed technical information. Major factors affecting stability of underground excavations in the selected cases are examined to identify conditions likely to cause ground failures and areas prone to ground instability. Based on these findings, a comprehensive approach is discussed to address ground control aspects in maintaining ground stability with the goal of improving the operational and safety performance of an underground mine.

1 INTRODUCTION

Stability of underground excavations has been analytically and numerically studied by many rock mechanics practitioners including Hoek & Brown (1980) and Brady & Brown (2004). Empirical approaches have been extensively utilized to design underground excavations. Most of these empirical methods involve application of rock mass classification schemes such as RMR (Bieniawski 1989) and Q (Barton et al. 1974). Statistical analysis of mining incidents has also been conducted to highlight functions with high injury rates. One such analysis is the statistical presentation of ground failure incidents in the South African gold mining industry by Jager & Ryder (1999).

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