Ground investigation, design and construction monitoring of a full-face tunnel drive in layered Quaternary deposits

Abstract

AbstractThe paper describes the results of ground investigations carried out to assess alternative methods of constructing a pipeline at shallow depth close to old buildings. A layered sequence of Quaternary alluvial and fluvio-glacial deposits is described, and high groundwater flows in gravels are linked to upstream underground sources in limestone. The effectiveness of two sets of ground probing radar equipment is assessed, and a maximum penetration of 4m is indicated where gravel layers are thickest. The first use in the UK of an Iseki Unclemole EPB tunnelling machine is described, and measurements of settlement and heave above the centre line of the pipeline indicate maximum vertical displacements of about 10mm. Mix design for the bentonite slurry face support is briefly discussed.