Joint properties and useful mapping techniques are key to fall of ground management in underground mining. This paper practically demonstrates how two mapping techniques were used to obtain joint data. A brief description of geological discontinuities at the study area is given in the paper. Joint mapping was carried out in both the North and South sections of the mine. Procedures followed when collecting joint data are also provided. The collected joint data was used to evaluate rock fall probability. Rock fall probabilistic analysis carried out in the study indicate that about 80% of all key blocks formed are 1 m3 in size. Results show that larger blocks are more likely to fail by means of rotation. Furthermore, to prevent small blocks from falling between support units, areal coverage is suggested in heavily jointed rock masses. Probabilistic analysis can be used to evaluate probability of rock falls, and support design for stability enhancement. This research is part of an MSc Engineering study.

1. INTRODUCTION

Unexpected rock mass movement may lead to uncontrolled release of rocks that can consequently cause injuries and fatalities. Unfortunately, the natural environment in which the mine is located in cannot be changed (Yilmaz, 2015). However, rock engineering is there to ensure that mining is carried out profitably and safely. The stability of underground excavations is a key concern in this field. As a result, focus is mainly on stability enhancement by means of excavation support designs and monitoring of ground conditions. Mining practices have an influence on the behavior of rock masses. This is because whenever an excavation is constructed in a particular rock mass, stresses are redistributed around the newly created excavation. Owing to these changes, risk assessments and close monitoring of the exposed rock mass are considered to be essential (Walke & Yerpude, 2015).

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