Railway embankment behaviour due to increased axle loads - A numerical study

Due to an increase in axle loads, the development of excess pore water pressure and settlement in a railway track foundation of fine-grained subgrade soil can be observed. A thorough understanding of the mechanism of development of excess pore water pressure is essential for understanding the development of settlements and the design of potential ground improvement. In this paper, a three dimensional numerical study is presented, which investigates the effects of an increase in axle loads of trains on both excess pore water pressure and settlement. Special attention is given to a soft soil layer beneath the embankment and the influence of ground improvement (deep soil mixing columns). As a result, an increase in axle loads leads to a considerable increase in both excess pore pressures and settlement in the subgrade layer. This increase is more significant in the case of heavy axle load (32.5 tons) than that of the light axle load (16 tons). In addition, cyclic loading can lead to a considerable increase in both vertical displacements and excess pore water pressure. The use of deep soil mixing columns reduces excess pore water pressures and settlements significantly.