Abstract: The mechanical properties of slip zone soil play a crucial role in determining whether a reactivated landslide will slide again. In previous studies, the residual strength of slip zone soil has been regarded as a static parameter. However, recent research has revealed a self-healing effect in which the strength of slip zone soil increases in stable period. This self-healing effect needs to be considered in the stability analysis of reactivated translational landslides. In this study, a shear-consolidation-shear test was conducted on the slip zone soil of a red-bed translational landslide. The aim was to investigate the self-healing of residual strength of slip zone soil under different normal stresses and consolidation durations. The findings demonstrate the presence of a self-healing effect in slip zone soil. The initiation strength of reactivated landslide falls between its peak strength and residual strength. Moreover, the strength recovery ratio of slip zone soil is directly proportional to consolidation duration and inversely proportional to normal stress. The thixotropy of slip zone soil in translational landslides is the main factor underlying the strength healing mechanism, with the mineral characteristics contributing to some extent. In conclusion, the strength healing mechanism of slip zone soil significantly influences the reactivation and initiation sliding of translational landslides.

Key words: translational landslide, slip zone soil, self-healing effect, shear test, residual strength