Review on the prevailing methods for the prediction of potential rock burst / rock spalling in tunnels

Rock burst / rock spalling is among the prevailing stability challenges, which can be met while tunneling through hard rock mass. Especially, this is very relevant for the mountainous country like Norway where hard rock is dominating and many road, railway and hydropower tunnels have to be aligned deep into the mountain with steep valley slope topography. Tunnels passing beneath deep rock cover (overburden), in general, are subjected to high in-situ stresses. If the rock mass is relatively unjointed and massive, which is the most likely case in Norway, a brittle failure may occur in the tunnel periphery, which is known as rock spalling / rock bursting. Establishing state of the stress and evaluating stress induced instability in tunnels passing through brittle rock mass at relatively greater depth is of course a challenge. This manuscript reviews and describes the existing rock burst prediction methods that are being practiced worldwide so that these can be used by professional engineers as base for the evaluation and predict potential rock burst / rock spalling scenario in the tunnels under planning and design. The manuscript describes each method itself, highlights extent of applicability and compares with other prediction methods