Numerical analysis of the influence of granular trench reinforcement of soft clay subgrade on the undrained dynamic response of a railway track

Abstract

Soft subgrade poses significant challenges to the designer of railway tracks due to its high compressibility and low shear wave velocity. The low shear wave velocity might affect the maximum design speed of the train. The stabilization of this soft soil improves its performance and reduces the expected settlement. However, little attention has been paid to understanding the feasibility of different stabilization techniques, as there are very few studies on this topic. Thus, this research study aims to determine the impact of granular trench reinforcement of soft subgrade on the dynamic response of a railway track subjected to a moving train load. Three-dimensional finite element analysis has been used in this research. The effect of the train speed and the depth of the granular trench has been carefully evaluated. It has been found that the critical velocity (which is the velocity that corresponds to the highest settlement) is not affected by the granular trench reinforcement. In addition, it has been noted that the granular trench reinforcement reduces the maximum settlement of the railway track under the moving loads, with a percentage reduction ranging between 1% and 24%. Furthermore, the granular trench reinforcement did not affect the acceleration induced in nearby areas due to the train’s vibration. The results of this research provide useful insight into the feasibility of the granular trench and help design engineers compare different solutions for the problems of soft subgrade soil.