�@Substructure is built with conventional reinforced concrete, and its stiffness is considerably high compared with peripheral subsoil. Accordingly to evaluate the influence that upper surcharge has on substructure, it is necessary to examine stress spots which occur on the structure top caused by difference in stiffness between structure and peripheral subsoil. On this subject, authors have done a series of model experiments. As a result, they propose paramenters expressing the degree of stress concentration and the relaxation of stress concentration due to deformation of the structure. Then they study how to apply these parameters to an analytical model to evaluate the influence of the action of upper surcharge.