The load sharing behavior of geosynthetic-reinforced and pile-supported high-speed railway subgrade under fill and dynamic loads

Abstract

Over soft soil area the geosynthetic-reinforced and pile-supported subgrade was often used to reduce the post-construction settlement. But after operation it was found that the settlement sometimes was bigger than required. For settlement evaluation the stress concentration ratio between pile and soil is very important and the arching effect is often considered to solve this problem. There are some methods to analyze the sharing of fill load, but the dynamic train loads were often ignored. In this paper the finite element was used to simulate the stress concentration ratio during fill stage construction and dynamic load which were compared with the in-situ test. The results during fill stage also were compared with EBGEO and BS8006. They showed that the reliability of current methods is related to some factors including fill height, the stiffness ratio of pile and soil. There is a critical filling height whether the dynamic load decrease arching effect or not. According to FE results, the critical height is 3m. When the filling height is smaller than 3m, the stress concentration ratio should be re-evaluated by the reduction factor.