ABSTRACT
The prediction of ground deformation due to shield excavation in sandy and gravelly ground is estimated based on the field observation. In this paper, the stress released ratio obtained from the observed earth pressure around the tunnel lining and the vertical ground deformation above the tunnel are discussed. Through this analysis, following aspects are pointed out; (1) The stress released ratio depends upon the construction process under the ground settlement control. (2) In sandy ground with a cohesion, 100% stress release is observed, that means only the water pressure acts on a tunnel lining. (3) The vertical deformation just above the shield tunnel is occurred locally. (4) The vertical deformation becomes small rapidly according to the distance from the tunnel. The conventional prediction method for ground deformation in sandy and gravelly ground is suggested based on the 2D-FE analysis used the stress released ratio and the empirical relation between the ground deformation and the distance from tunnel.
