The paper describes observed behaviour of a model tunnel embedded in dry sand subjected to cyclic ground shear deformation in a centrifuge, as well as the behaviour of the model ground during shear deformation. Detailed data on earth pressures acting on the tunnel lining and the sectional forces of the lining are presented during ground shear deformation. The data suggest that the earth pressure at tunnel crown before ground shear deformation is smaller than the full overburden pressure probably due to the formation of arch action and the arch action may deteriorate with the cyclic ground shear deformation, resulting in an increase in the earth pressure at crown and changing the distribution of the sectional forces, which are largely in‰uenced by conditions between tunnel lining and invert.
A comparative study of centrifuge dynamic shake table test and centrifuge pseudo-static shear box test was conducted on the same prototype model to experimentally examine applicability of the seismic displacement method which is adopted in seismic design for underground structures in Japan. The model used was a rectangular shape tunnel embedded in dry sand. The detailed strain measurements were made on the model tunnels as well as relative displacement between upper and lower slabs of the tunnel for direct comparison between the results obtained from the two different test types. The study confirmed that the centrifuge pseudo-static shear box test provides valuable information on structural responses which are very much similar to those observed in the centrifuge shake table test.
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