Dynamic pro-infiltration triggers collapse sinkholes in urban loess roads: Insights from physical and numerical modeling

Understanding the formation of collapse sinkholes in urban loess roads caused by dynamic loading and pipeline leakage is challenging in engineering geology and environmental investigations. The influences of dynamic loading on infiltration behavior and its collapse sinkhole-causing process remain elusive. Here, we evaluate the impacts of dynamic pro-infiltration and its sinkhole-causing process via physical and numerical simulation approaches. This allows us to estimate the critical physical and mechanical parameters that best describe water movement under the influence of vehicle dynamic loading and its disaster-causing effects. The results reveal that the infiltration behavior of the loess subgrade is enhanced by dynamic loading because of the acceleration of wet front migration, the increase in the infiltration rate, the increase in the pore pressure, and the aggravation of the erosion process. Moreover, these promotional effects are most remarkable when the frequency of the applied dynamic load is close to the resonance frequency of the subgrade soil. The formation of collapse sinkholes in urban loess roads due to dynamic pro-infiltration exhibits evolutionary features of three stages and five steps i.e., the cumulative stage of damage due to dynamic infiltration (saturated softening of seepage and vibration promoting infiltration fracturing), the stage of erosion loss due to dynamic loading–infiltration (vibration scattering and erosion, which causes penetration and vibration–collapse, which causes loss and holes) and the stage of dynamic infiltration promoting deterioration–shearing–impact collapses. In addition, the underlying causes of the formation and prevention strategies of typical collapse sinkholes in urban loess roads triggered by dynamic pro-infiltration are investigated. Our findings not only advance the understanding of sinkhole hazard occurrences in urban roads but also offer promising insights for creating safer, more resilient, and sustainable urban geological environments.