Abstract
The need for accurate predictions of tunnelling-induced ground movements has led to increased research activity over the past 30 years. However, there has been very little investigation into the problem of tunnelling in multi-layer ground or the associated subsurface movements. This paper presents data from a series of centrifuge model tests aimed specifically at investigating the effect of stiffness of an overlying layer on ground movements above tunnels driven in clay. Results of the tests indicate that the stiffness of the upper strata has a significant influence on the distribution of movements in the lower clay layer and current design methods of settlement prediction may then under-estimate the width of the subsurface settlement troughs.
