An evaluation method for the sliding displacement of retaining structures and soil slope is proposed in this paper. The evaluation method employs a vibration-sliding model which consists of mass, spring with dashpot, and slider to take account of the vibration properties of structure. The calculation results with this model are summed up in a form of response spectrum, where the calculated sliding displacement is plotted against the natural frequency of the structure with parameters such as damping and sliding margin. The sliding response spectrum can be applied to the retaining structures, as well as soil slope.
In the earthquake resistant design of structure and soil slope, a performance-based method is lately preferably employed instead of a conventional safety factor-based method. In the performance-based design, a certain degree of performance of the structure must be guaranteed even after the application of an earthquake of assumed intensity. In order to conduct the earthquake resistant design satisfactorily, the degree of the damage to the structure must be estimated quantitatively; the sliding displacement is a primary important factor as an index of the damage for retaining structures and soil slopes. The deformation behavior of earth structures during earthquake is rather complicated due to the nonlinear and inelastic stress-strain behavior of soil, and the various environmental factors affecting the mechanical properties of soil. Sometimes sophisticated numerical calculation method such as Finite Element Method is employed for the simulation of the vibration behavior, and the huge amount of effort is exerted on the prediction of the damage to the structure. The setting up of the numerical model; i.e. the selection of appropriate input parameters and determination of the input values, are, however, complicated. It must be said that obtaining objective and reliable calculation results is difficult even with ample experiences in the study and research in the earthquake geotechnical engineering.
