Centrifuge model tests on shallow overburden tunnels with pre-ground improvement to clarify seismic behavior

Abstract

Due to the development of auxiliary construction methods, such as pre-ground improvement, the NATM is often used to excavate tunnels with a shallow overburden in a soft ground. The improvement stabilizes the tunnel face and suppresses the subsidence of the ground surface. In previous researches, although the optimum ground improvement area was examined through experiments and numerical simulations, the seismic behavior of the tunnels was not clearly discussed. In this study, dynamic centrifugal model experiments are conducted to clarify the dynamic behavior of shallow tunnels with pre-ground improvement. The experimental results indicate that when the entire ground around a tunnel is improved, the shear deformation of the tunnel can be suppressed. On the other hand, when the ground around the tunnel crown and top section is improved, the response of the tunnel is amplified by the concentration of weight at the upper part of the tunnel.