Permanent Deformation Behavior of Compacted Loess under Long-Term Traffic Loading

Abstract

The long-term permanent deformation behavior of subgrade soil repeatedly subjected to traffic loading has a significant effect on the settlement of pavement during operation. Many studies conducted on this topic have focused on granular materials, marine soft soils, frozen soils, or fouled ballast. However, the deformation behavior and cyclic strength of compacted loess subjected to traffic loading have undergone limited investigation. In this study, the development of permanent strain in compacted loess was addressed using a number of cyclic triaxial tests. The effects of cycle number, cyclic amplitude, and confining pressure were examined in detail. Permanent strain was separated into two broad categories: the initial strain generated by the first cycle and the accumulated strain generated by subsequent cycles. Furthermore, a predictive formula was proposed in order to describe the mechanism by which permanent strain varied according to cycle number, cyclic amplitude, and confining pressure. Linear fitting was employed in order to establish the relationship between the initial strain and the amplitude of cyclic stress, and a log function was used to establish a correlation between accumulated strain and cycle number. In addition, the cyclic strength of compacted loess was also addressed. The results indicate that initial strain exhibits an ostensibly significant effect on the distribution of cyclic strength versus cycle number and contributes to a large proportion of overall permanent strain, especially at a low cyclic-stress level.