Investigation and treatment of abandoned mine workings for underground excavations: an example from the Don Valley Intercepting Sewer scheme, Sheffield, England

Abstract

AbstractThe Don Valley Intercepting Sewer is being constructed to upgrade the sewerage system of the City of Sheffield. The principal objectives of the scheme are to alleviate flooding, reduce the frequency and amount of sewage discharges to the surface watercourses, provide adequate drainage capacity for present and projected flows and allow access to the existing sewerage system for cleaning, inspection, repair and renovation.To achieve the operational objectives and provide favourable ground conditions for the construction of the scheme, the tunnels are driven at a low level in a sequence of Coal Measures strata which comprises the solid geological formation of the area. This sequence includes a number of coal seams, formerly of economic importance, which have been exploited by opencast and subsurface mining extraction methods from historical times to as recently as 1954.Investigation were undertaken to establish the ground conditions in an area where a tunnel drive was to traverse a coal seam in which abandoned shallow mine workings were recorded. The data collected during the desk study and field investigations are discussed with reference to the design and construction of the tunnel works. Ground treatment was carried out by cementiteous grouting and a detailed account of the methods adopted is given.