Subsidence owing to tunnelling. I. Estimating the gap parameter

Abstract

A simple, numerically based procedure for the estimation of the so-called gap parameter is described. The gap parameter represents the vertical displacement above the crown of the tunnel and is a measure of ground loss owing to tunnelling in soft ground. This parameter is a function of the three-dimensional elastoplastic deformation at the tunnel face, the tunnelling machine shield and lining geometry, and workmanship. This parameter can then be used to predict the resulting ground deformations using either two-dimensional finite element methods or empirical correlations. Key words : tunnelling, settlement, subsidence, clays, soft ground, analysis, design.