Dynamic Response of Shallow Rectangular Tunnels in Sand by Centrifuge Testing

A series of dynamic centrifuge tests on rectangular tunnel models embedded in dry and saturated sands is presented. The tests were carried out at the geotechnical centrifuge facility of IFSTTAR in Nantes, France, within the Transnational Access action DRESBUS II funded by the SERIES research project. The experimental program focused on salient parameters controlling the dynamic response of the soil-tunnel system such as soil-to-tunnel relative flexibility, soil-tunnel interface characteristics, soil saturation and characteristics of the input motion. Among the innovative features of the experimental set up were sand pluvation, models saturation and tunnels waterproofing techniques. A dense monitoring scheme was implemented, including accelerometers, displacement sensors, pore pressure sensors and specially designed extensometers for measuring side-wall deformations and diagonal distortion of the tunnel. A preliminary interpretation of the experimental data revealed the effect of the above parameters on the racking deformation modes of the tunnel sections.