Use of a two-dimensional discrete-element line-sink model to gain insight into tunnelling-induced deformations

Abstract

A two-dimensional discrete-element model (DEM) is shown to provide useful information regarding the kinematics of ground deformation in response to tunnelling. Tunnel excavation and construction is a highly complex process and the line-sink model approach used in previous analytical studies provides a simple means to simulate the excavation process. A virtual sand box was created using DEM and grains were progressively deleted to simulate the sink. The surface settlement trough was determined and, when normalised by the maximum settlement, its shape was nearly constant and closely fitted a Gaussian curve. The deformations observed gave a good approximation to the displacement field predicted using the Verruijt and Booker analytical line-sink model. This preliminary study suggests that a simple line-sink DEM may provide a robust basic frame of reference for the complex mechanisms of ground movement around soft ground tunnels. More generally the results demonstrate the potential of using particulate DEM to study ground response to tunnelling.