Cyclic triaxial tests with intermittent cyclic loading are usually used to investigate the deformation behaviors of soil; however, both deviator stress and confining pressure vary cyclically under traffic loading. Moreover, the pore water in soil can be dissipated throughout the test, affecting the mechanical behaviors of soils. Therefore, in this study, three test modes were applied to saturated soft clay to analyze the deformation behaviors, in which different cyclic confining pressures were used during cyclic loading periods, and different drained conditions during cyclic loading and intermittent periods were considered. The variations in strain increment were similar in all cases: as the loading stages progressed, the strain increment gradually diminished. The distinct variation in strain increment became evident in the initial loading stage, but it became negligible in subsequent loading stages. Furthermore, the change in strain increment with respect to cyclic confining pressure was influenced by drained conditions during the cyclic loading period: it increases as the cyclic confining pressure increased under partially drained conditions and decreases under undrained conditions. Moreover, the strain increased under partially drained conditions during intermittent periods, companying with the discharge of pore water, while it decreased for the recovery of specimen deformation under undrained conditions. The greater strain increment was caused under partially drained conditions during cyclic loading periods compared with the corresponding strain increment under undrained conditions. Besides, an empirical model was developed to forecast accumulated axial strain of soil subjected to intermittent cyclic loading, and the variations of parameters under different drained conditions were studied.

This study aims to explore the accumulated behavior of reinforced coarse-grained soils through cyclic triaxial tests and to develop a prediction model for the plastic shakedown limit. Cyclic triaxial test results illustrate that the reinforced specimens, especially those incorporating geocells, demonstrate the lowest accumulated axial strain and the highest plastic shakedown limit when compared to unreinforced ones under identical cyclic loading. Additionally, the accumulated axial strain at the plastic shakedown limit for reinforced specimens is determined. This strain is then used to determine the additional confining pressure exerted by geogrid or geocell, employing a function proposed by Yang and Han. By integrating the additional confining pressure into the plastic shakedown criterion for unreinforced specimens, a prediction model for the plastic shakedown limit in reinforced specimens is ultimately established. The model's applicability and the accuracy of computed additional confining pressure values are validated using experimental data.

The dynamic behaviors of subgrade soil are usually investigated by use of continuous loading mode in most studies; however, the dynamic loading induced by traffic loading is composed of cyclic loading and intermittent periods. Moreover, the existence of cyclic deviator stress, cyclic confining pressure, and shear stress has been already observed in the stress field induced by traffic loading. Recognizing this, intermittent cyclic loading was applied to saturated soft clay for this study. The impacts of cyclic deviator stress, cyclic confining pressure, and drained condition during intermittent periods on the deformation behaviors of soft soil were analyzed. The variations in strain increment were similar in all cases: as the number of loading stages increased, the strain increment decreased, and the difference in strain increment was more significant in the first loading stage although it could be ignored in subsequent loading stages. Furthermore, the strain increment increased with increasing cyclic stress ratio (CSR) and decreased with increasing cyclic confining pressure. Moreover, the dissipation of excess pore-water pressure induced during the cyclic loading period resulted in the increase of accumulated axial strain under intermittent partially drained conditions, while the recovery of specimen deformation during intermittent period led to the decreasing of accumulated axial strain under undrained conditions. In addition, an empirical formula of accumulated axial strain under intermittent cyclic loading was established, and the calculated results were consistent with the measured data.

Both cyclic loading on soil and intermittent periods come into play with the passing of trains. However, the existence of both cyclic deviator stress and cyclic confining pressure has already been observed in the stress field. In this paper, two types of cyclic triaxial tests, i.e., continuous cyclic loading and intermittent cyclic loading, were conducted to study the deformation behaviors of soft clay. The effects of cyclic confining pressure, duration of intermittent period (i.e., intermittent time), and loading cycles were analyzed. Compared to continuous cyclic loading, the intermittent period has a substantial influence on the deformation behavior of soft clay: the strain produced by intermittent cyclic loading is larger than that produced under undrained conditions, but less than that generated under partially drained conditions. The increment of accumulated axial strain corresponding to each loading stage under various factors was compared: an increase in intermittent time and loading cycles leads to greater degradation of the increment of accumulated axial strain, while the greater cyclic confining pressure corresponds to lower the increment of accumulated axial strain. The differences in the increment of accumulated axial strain for various loading cycles and cyclic confining pressures are significant in the cyclic loading period of the first loading stage, and can be ignored in subsequent cyclic loading periods. Besides, an empirical formula is provided to calculate the total accumulated axial strain caused by intermittent cyclic loading, and the predicted results accord well with the measured data.

This research explores how the dynamic behaviour under cyclic compression loading affects compaction characteristics. Three types of sand, varying in fines content, are compacted under different saturation (${{\rm{S}}_{\rm{r}}}$Sr) and compaction (${{\rm{D}}_{\rm{c}}}$Dc) levels. Suction-controlled drained cyclic loading tests are conducted to predict axial strain accumulation, with initial suction measured for each compacted state. The study seeks to understand the correlation between axial strain accumulation and initial suction across soil types. Findings indicate that initial soil suction, influenced by saturation, significantly impacts axial strain under cyclic loading. Lower saturation enhances particle bonding, increasing initial suction and reducing strain accumulation. Moreover, an increase in fines content results in greater strain accumulation. Despite that, sands with elevated fines (18.8%) can achieve similar soil performance through effective compaction with precise saturation control. This underscores the role of saturation in moisture regulation during compaction, particularly for sands with higher non-plastic fines content, in achieving effective compaction.