ABSTRACT
Centrifuge model tests on shallow tunnels in sand were carried out to investigate ground deformation caused by tunneling. An image processing system was introduced to measure displacements of the targets accurately which were attached in the model to observe ground deformation. This system can measure displacements of the targets with the accuracy of 0.1 mm or better in these tests. Strains in the model are calculated from them. Through the observation of ground deformation, it was found that arching in the ground was formed by dilation with shear deformation and was not formed until some deformation developed, that the deformation when arching was formed depended on the density of sand around a tunnel, and that an arch was made even in a shallow tunnel.
