Dynamic stress attenuation characteristics of geocell-reinforced railway subgrade

Abstract

The dynamic stresses in many subgrades for old railways exceed the bearing capacity of the fillers. The geocell has been used to reinforce weak subgrades and achieve a quick attenuation in the dynamic stress. In this study, a series of field tests were conducted to investigate the dynamic stress attenuation characteristics in a weak subgrade reinforced with a geocell. A coupled finite element-discrete element model was developed to analyze the mechanism of the stress attenuation from a multiscale perspective. The results indicated that increasing the geocell height or decreasing the weld distance resulted in an increase in the attenuation rate. There was a threshold for the weld distance, below which its impact on the stress attenuation rate became negligible. When the weld distance was small, the dynamic stress attenuation was attributed to the geocell induced lateral confinement for the infilled soil. With the weld distance increasing, the deformation of the geocell increased and the membrane effect was further mobilized, which contributed to the dynamic stress attenuation. Based on the field test and numerical results, a design method was proposed to determine the reinforcement parameters of geocell-reinforced subgrade, aimed at improving dynamic stress attenuation and preventing subgrade distress.