A similitude is derived for the shaking table tests on saturated soil-structure-fluid model in 1g gravitational field. The main tool used for deriving the similitude is the basic equations which govern the equilibrium and the mass balance of soil skeleton, pore water, pile and sheet pile structures, and external waters such as sea. In addition to the basic equations, an assumptions is made upon the constitutive law of soil; i.e. the stress-strain relation is determined irrespective of the confining pressures if appropriate scaling factors are introduced for the tstress and the strain for taking the effect of the confining pressures into account.
　Applicability of this assumption is examined by using the presently available data under the confining pressures ranging from 0.05 to 1 kgf/cm2 (from 5 to 98kN/m2) or 0.05 to 4 kgf/cm2 (from 5 to 392 kN/m2) . The results indicate that the assumption is appliocable within the intermediate strain levels; i.e. the strain levels which are lower than the strains at failure. In consequence, the similitude derived in the present study is applicable to the model tests in which the major concern is directed toward the deformation, rather than the ultimate state of stability, of the soil-structure-fluid system.