Effect of Vehicle Cyclic Loading on the Failure of Canal Embankment on Soft Clay Deposit

Road embankments along irrigation canals, constructed on soft Bangkok clay, have always been unstable. Numerous studies have shown that rapid drawdown of water level may be one of the main causes, while vehicle cyclic loading may also contribute to embankment failure. This study aims to investigate the impact of vehicle loading on the failure of embankments built on Bangkok soft clay. The behavior of soft Bangkok clay under vehicle load has been investigated by employing conventional and dynamic triaxial techniques, and finite element method (FEM). This study also examined the effects of soft clay thickness and cyclic loading with different magnitudes and frequencies. The laboratory testing results indicate that the threshold stress of the soft clay is estimated to be approximately three-fourths of the undrained shear strength of the soil. The reduction in effective stress in the soft clay is caused by varied frequencies and thicknesses of the clay. Based on the analysis results, it has been proven that the cyclic loads exerted by vehicles solely are insufficient to cause the embankment to collapse. Nevertheless, the repetitive loading of vehicles may result in a one-quarter decrease in the embankment’s factor of safety.