Mechanism of caving in longwall coal mining
M.D.G. Salamon
Abstract
Longwall extraction, in conjunction with caving, is one of the most widely practised underground coal mining methods. Caving and the subsequent reconsolidation of the caved rocks combine to form a mechanism which is kernel to the solution of several important problems. In spite of the central role of caving to the success and safety of this method of mining, no comprehensive attempt appears to have been made to provide a quantitative explanation of the processes involved. Investigators have, from time to time, presented reports on their measurements of the deflection of the strata above longwall workings (e.g. Salamon et al 1972, Hol 1 a et al 1986, Bhattacheryya et al 1987). It would seem, however, that the first substanti ve look at the problem was prompted by the widespread presence of massive dolerite sills in some important coal producing areas of South Africa (Salamon 1966, Salamon et al 1972). The successful control of the caving process when the working panel is overlaid by one of these competent sills, was a major factor in the feasibility of longwalling in these regions. The present aim is to broaden and apply the ideas presented in those earlier reports.