Scour-Induced Bearing Capacity Degradation of Strip Foundations under Vertical, Horizontal, and Moment Loading

Abstract This study investigated scour-induced degradation of shallow and intermediate strip foundations subjected to vertical, horizontal, and moment loading using adaptive finite element limit analysis. Soil cohesion, friction angle, embedment ratio, and normalized scour depth were varied over 5–30 kPa, 5°–40°, 0.5–2.0, and 0–1.0, respectively. Lower- and upper-bound collapse loads were used to calculate normalized scour influence factors, and two-level surrogate models were developed to express capacity degradation as functions of normalized scour depth and soil-foundation parameters. The results showed progressive reductions in all three capacities as scour removed supporting soil and altered the mobilized failure mechanisms. Grouped six-fold cross-validation yielded out-of-fold coefficients of determination of 0.909–0.976, with root mean square errors of 0.028–0.076 and mean absolute errors of 0.015–0.050 across the selected surrogate formulations. Sensitivity analyses showed that scour-hole geometry and the assumed dilation angle had greater effects on horizontal and moment responses than on vertical response. The resulting influence factors provided a practical means of incorporating prescribed scour depths into conventional bearing-capacity calculations.