Analysis of Tunneling-Induced Ground Movements Using Transparent Soil Models

Abstract

Ground movements induced by shallow tunnels affect the safety of nearby underground and aboveground structures. Therefore, the reliable prediction of these movements is important. A transparent soil model is used to investigate not only the surface settlement profile induced by shield tunneling, but also the distribution of soil deformation within the soil mass near the tunnel. The observed surface settlements are consistent with the normal probability curve commonly used for predicting settlement, with only the inflection points or trough width parameters somewhat different. The measured data are consistent with field measurements in that the trough width parameter is independent of the volume loss and linearly proportional to the tunnel depth. An analysis of the displacement field inside the transparent soil models indicates that the subsurface settlement trough at different depths can be approximated by a normal probability curve; and the horizontal displacement can be expressed by the trough width parameter and the volume loss, at the point at which maximum horizontal displacement occurs at the point of inflection. Additionally, the measurements indicate that subsurface ground movements can be in excess of the observed surface settlement, which can adversely affect underground utilities.