Abstract
In this study, cyclic loading tests were carried out on model grounds simulating the conditions of track and roadbed in the clayey roadbed section of the Tokaido Shinkansen, in order to verify the mechanism which causes frequent maintenance locations. Effects of the ballast layer thickness and the water intrusion on the track settlement were investigated. The model grounds were set to 1/5 size of the real ones, and based on the field survey results, they were consisted of three layers of ballast, fouled ballast and ballast mixing loam, respectively. The test results show that as the ballast layer thickness (the sum of ballast and fouled layer thickness) decreases, the settlement amount in the initial stage of loading become smaller, but as the saturation degree of the roadbed surface layer increases the settlement rate becomes higher because the earth pressure acting on the roadbed surface become higher and the road surface softens. It was also found that the thicker ballast layer can significantly lower the settlement even though the degree of saturation of the roadbed is increased.
