Abstract
Foundations for embankment dams are often composed of soft rocks in Japan. Therefore, it is important to precisely predict deformation of the foundation due to an embankment to evaluate the safety of the dam and its foundation. Plate loading tests are generally utilized to evaluate the deformation characteristics of dam foundations. Looseness in surface layer due to excavation could affect the accuracy of plate loading tests. We made numerical study using FEM analysis on the influence of looseness on results of plate loading tests. Two evaluation methods of deformability of the foundations excluding the influence of looseness in surface layer are also studied. One is the method using observed vertical strains in the ground along the central axis of the circular loading plate, the other is the method using the plate loading tests with three circular plates of different diameters.
Consequently, the larger the magnitude of depth and degree of looseness is, the larger the evaluation error of the deformability is. In addition, it is found that two proposed methods make it possible to evaluate deformability of the foundation without the influence of looseness in surface layer.
