Quantifying the influence of structure, rock mass strength and mining development of drives in squeezing ground

ABSTRACT Squeezing ground conditions are observed in several underground hard rock mines characterized by preferential structural features. Mining drives developed in squeezing ground conditions report very large deformations over their working life. This paper reports on a long term study of the observed very large deformations in mining drives at the LaRonde and Lapa mines in north-west Quebec, Canada. This analysis followed a comprehensive instrumentation, rock mass characterization and monitoring programme at the two mines. Drive convergence measurements were analysed and employed to quantify the role of structure, strength and mining development in squeezing ground conditions. The observed levels of drive convergence were considerably higher than previously reported in other hard rock mines. This paper reports on a quantitative interpretation of the rock mass, stress and design parameters that control the degree of squeezing. These observations have significant influence for the design and mitigation of mining drives in squeezing ground conditions.