The relative cuttability of coal-measures stone

Abstract

Over the last quarter of a century a range of machines has been developed at Stanhope Bretby for the drivage of tunnels and roadways, and for the construction of holes and openings, in stone in the Coal Measures. About three-quarters of drivages by the NCB are now mechanised, the limitation being the strength and obrasivity of the stone. This paper summarises the technology used in these developments. It relates only a stone in the Coal Measures; the resilience, friability, jointing and lubricity of coal itself cause coal to behave differently. On the other hand, Coal-Measures stone is sufficiently consistent to respond to certain rules, although these may not apply to all rock in the Earth's crust. It is submitted that the paper might form a working summary of relevant characteristics of Coal-Measures stone and associated machines, for project engineers concerned with stonework. Stonework machines are capital-intensive so that abusage is inevitably matched by the severity of financial penalty; the most beneficial characteristics that can be developed in them is flexibility.