Multi-Field Responses and Failure Mechanisms of Loess Slopes under Engineering Disturbance and Extreme Rainfall: Implications for Sustainable Slope Management

Jinfeng KeLongsheng Deng^*Wen FanChao Zhang

• Chang’an University, Xi'an, China

In the context of climate change, elucidating the stability of loess slopes impacted by engineering interventions and extreme rainfall is essential for sustainable slope management in loess terrains. This research employs a 1:20 large-scale physical model to systematically examine the multi-field responses and failure mechanisms of loess slopes subjected to combined surcharge, excavation, and sustained rainfall, with continuous monitoring of stress, volumetric water content, pore-water pressure, and deformation dynamics. The findings demonstrate: (1) Engineering activities induce significant stress concentrations that are further intensified and driven downward by rainfall infiltration; in the late stage, peak vertical stress surpassed 150 kPa, indicating pronounced stress redistribution. (2) Rainfall infiltration is characterized by pronounced spatial and temporal variability, with the shallow soil layer rapidly reaching saturation, while deeper strata exhibit delayed water migration and a gradual buildup of pore-water pressure. After approximately 15 hours of rainfall, a sharp increase in pore-water pressure was observed, particularly in the mid-to-lower slope toe, which considerably diminished effective stress. (3) The progression of slope failure follows the sequence of "shallow softening →shallow mud-induced sliding →toe-shear failure →flow-plastic/liquefied sliding," with shallow failure events preceding deep-seated instabilities. These insights elucidate the underlying mechanisms by which engineering disturbances and rainfall infiltration interact to govern loess slope instability, providing a scientific basis for slope management, early warning systems, and risk mitigation strategies in loess regions under extreme rainfall conditions.