Bridge Foundation Instability under Climatic Extremes: Experimental and Numerical Insights into Driftwood and Seepage Impacts
Bridge Foundation Instability under Climatic Extremes: Experimental and Numerical Insights into Driftwood and Seepage Impacts
With recent shifts in global climate patterns, increased rainfall has become more frequent, posing significant challenges to road infrastructure. Bridges, critical links in national transport networks, have suffered structural damage due to the accumulation of sediment and driftwood at piers, which induces damming upstream and alters hydraulic behaviour. In this research, a series of physical model experiments, supported by rigid plastic finite element simulations, were conducted to evaluate the influence of waterhead differences generated by damming and the application of lateral forces simulating driftwood accumulation. The results revealed that the damming effect initiates upward seepage flow beneath the foundation, reducing effective stress and consequently the shear strength of the soil. Simultaneously, increased lateral forces caused by the girder being submerged in water due to the driftwood capture promote sliding and tilting of the pier. These deformations, in turn, exacerbate internal and external erosion and contribute to a brittle geotechnical failure of the foundation system. A method was proposed to evaluate this complex failure phenomenon, incorporating the combined effects of hydraulic head, debris loading, and progressive soil weakening through this research. The proposed equation captures the mechanisms as observed in the experiments, demonstrating significant loss of vertical and horizontal resistance. These findings highlight the need to consider the interplay between internal seepage-driven soil degradation and external driftwood-induced forces when assessing the stability of bridge foundations under extreme climatic and hydrological conditions.
S. Ali; Yutaka Nagoya; Koichi Isobe; N. Quang Pham; T. Hoshina
11th International Conference on Physical Modelling in Geotechnics (ICPMG2026)
Special Session 5: Combination of numerical and physical modelling
https://doi.org/10.53243/ICPMG2026-195