Lateral and vertical bearing characteristics of monopile and pile groups under scour condition: model test and calculation method

With the rapid development of offshore wind power and cross‒sea bridges, the negative impact of scour on the bearing capacity of pile foundations has garnered increasing attention. While pile groups are more widely applied in engineering practice, most studies on scour effects have primarily focused on single piles. This study presents a series of laboratory static load tests, both vertical and lateral, on the monopile, five‒pile, and nine‒pile foundations. The study thoroughly investigates the variations in bearing capacity, pile moment distribution, group pile efficiency factor, and load‒sharing ratios under different scour conditions. The findings indicate that, similar to single piles, the lateral bearing capacity of pile groups decreases as the scour depth increases. Both lateral and vertical group pile efficiency factors increase with the intensification of scour, whereas under identical conditions, they exhibit a decrease as the number of piles increases, with the rate of reduction progressively diminishing. Among the pile group configurations, the corner piles in the front row are the most affected by scour depth and lateral loading. Therefore, the study suggests that effective reinforcement measures should be incorporated into the design of front corner piles. Additionally, this study establishes modified p‒y curves that account for the impact of scour dimensions based on the strain wedge model. Parametric analysis of scour depth, width, and slope angle further elucidates the influence of scour on the bearing characteristics of both single piles and pile groups, providing crucial insights for engineering design.