In deep underground mining and construction, high stress-induced rock fracturing is inevitable.1 Rock near the boundary of an excavation is confined in the tangential direction, and the volume increase due to rock failure is often translated into a significant convergence of the excavation boundary, and this phenomenon is known as rock mass bulking.2 Fig. 1 shows how the periphery of an excavation can deform from the original shape (shown as a dashed line) to a new shape (shown as the solid interior line), as a result of an increase in volume of the shaded failed zone. Rock mass bulking can cause problems when the wall displacement exceeds the displacement capacity of the support elements.3,4 In extreme cases the wall deformation can be very large, reducing the effective span of the drift and making the drift unsuitable for mining access. Thus, it is important to predict and manage rock mass bulking when mining in highly stressed grounds
