Liquefaction Behavior of Root-Reinforced Soil under Cyclic Loading

Vegetation plays a vital role in the ecological protection of both natural and engineered environments. Its mechanical reinforcement, derived from the additional shear strength provided by roots, is beneficial for maintaining the stability of geotechnical structures, such as slopes. Although existing research has made some progress in understanding the dynamic deformation behavior of root–soil composites, in-depth studies specifically focusing on their antiliquefaction characteristics remain limited. Furthermore, the dynamic response mechanisms of root systems given that liquefaction conditions require further investigation. This study aims to address these gaps by conducting a series of undrained dynamic triaxial tests to examine the cyclic behavior and antiliquefaction performance of rooted soil. Using the root system of Ficus virens seedlings as the research subject, this study explores the effect of varying lateral root angles on the dynamic response of the soil under cyclic loading. The results indicate that a decrease in the angle between lateral roots and the horizontal plane significantly enhances the soil’s resistance to liquefaction. Interestingly, the presence of roots inhibits two-way axial strain, which influences the symmetry of the dynamic hysteresis curve; this asymmetry shifts with changes in confining pressure. Additionally, the development pattern of excess pore water pressure (EPWP) varies with the incorporation of roots, prompting the proposal of a modified EPWP model specifically for rooted soils. Overall, rooted soils demonstrate a greater capacity to resist liquefaction at higher seismic magnitudes, leading to the development of an empirical model for the cyclic resistance coefficient based on different lateral root angles.