Tunnel boring machines (TBM) are increasingly used for excavating subsurface infrastructure such as road and railway, water supply and sewer tunnels, to name a few applications. When designing a hard rock TBM drive it is necessary to appreciate all interactions of the rock mass to be tunnelled with the TBM. This paper deals specifically with these interactions and suggests an integrated approach in estimating hard rock TBM performance, such as the penetration rate, the advance rate and the disc cutter wear.