ABSTRACT
This paper discusses the mechanics of shotcrete roof support for flat or moderately arched drift backs in moderately jointed hard rock environments ranging in geotechnical quality from Q’ = 0.2 to 20. The mechanism of support in rectangular hard rock tunnels is a combination of stiffness, shotcrete-rock adhesion, shear and tensile strength and flexural behaviour and toughness of both the shotcrete itself and of the composite shotcrete-rock assembly. Material properties are available from standard testing that quantify each of these mechanistic components, but the interaction of these components, and therefore the final support behaviour, is more challenging to realize. Through field testing and numerical simulation, it is the goal of ongoing research to quantify the composite capacity of the rock-shotcrete system for design purposes.
