This paper presents a methodology to investigate the structural stability of ventilation raises in jointed rock. Structural data are used to generate fracture systems and limit equilibrium techniques are employed to determine the stability of all wedges formed along the walls of an excavation. This methodology facilitates comparisons between different design options for ventilation raises.
The successful operation of underground mines relies on the development of infrastructure to provide reliable access and transfer of material and resources. This involves the excavation of shafts, drifts, ventilation raises, crusher stations, maintenance garages, storage areas etc. Material handling, production and geomechanical considerations influence the design of these structures in rock.
It is of interest to note that there has been considerably less effort in advancing the design of vertical or near vertical excavations (shafts, ventilation raises, ore and waste passes) than tunnels and mine entries. A plausible explanation for this dichotomy has been proposed by Sadaghiani & Bieniawski (1990). In reviewing shaft design practice they suggested that this may be due to ?the large amount of horizontal openings (in total length)?..and a misconception that tunnel design can be directly applied to shafts. Sadaghiani & Bieniawski (1990) further argue that mine shafts are often over-designed given their relative importance to a mine. A comprehensive design methodology for raised bored shafts has been proposed by McCracken & Stacey (1989). This methodology which draws from the Q classification system is applicable to the design of ventilation shafts.
This paper investigates the structural stability of ventilation raises in jointed rock. Structural data are used to generate fracture systems and limit equilibrium techniques are employed to determine the stability of all wedges formed along the walls of the excavation. This methodology facilitates the evaluation of different design options for ventilation raises.