Abstract:Based on the effective stress principle of saturated soil, a dynamic model for saturated soil-underground utility tunnels (UUT) interaction is presented. During modeling, the soil was considered as a solid-liquid two-phase media, and the Duncan-Chang constitutive model was used under statistic load, while the Davidenkov model was used when the tunnels were subjected to the action of seismic waves. The viscous-elastic artificial boundary condition of saturated soil was considered, and the ground motions were translated into dynamic load applied to the artificial boundary nodes. The influences of time histories, PGAs, incidence angles of input earthquake waves, porosity of soil, and ground stress fields on the seismic response of UUT were investigated. The following conclusions were drawn from the above analysis:(1) The deformation of structure reaches a maximum when the predominant period of an earthquake wave is close to that of the site, and the deformation of structure increases with increasing PGA and incidence angle of the seismic wave; (2) pore water pressure in the soil is one of main influencing factors in structure deformation; (3) the deformation of structure in single-phase media is much larger than in two-phase media, and the results, based on effective stress methods, were in accord with those based on single-phase media and structure dynamic interaction models subjected to the equivalent load of earthquake waves in saturated soils.