A review of rock abrasiveness testing for tunnelling

The abrasiveness of rock is one of the factors of concern to the engineer considering the excavation of a tunnel in rock by either a full-face or a partial-face tunnelling machine. For even if the rock is not too strong for mechanised excavation, wear of the tools of the tunnelling machine if the rock is abrasive may render the operation costly. The strength of the rock is commonly assessed directly by a test such as the uniaxial compressive strength test carried out on cylindrical specimens, or indirectly by a test such as the Schmidt hammer test carried out on an exposed rock face or on the surface of a core sample. There is, however, no accepted standard test to assess how abrasive a rock is although a…