Investigation of the protection mechanism and failure modes of solidified soil utilized for scour mitigation

Abstract

In recent years, the expansion of offshore wind farms has been substantial, with monopiles being a significant component contributing to the overall investment costs. While they provide clean energy, scour around offshore wind turbine (OWT) foundations presents significant engineering challenges. Recently, solidified soil has become a popular attempt to enhance scour resistance of the seafloor materials around foundations. Although the mechanical behaviors of solidified soil used in ground improvement on land have been investigated comprehensively, however, the scour protection mechanisms of solidified soil and its failure modes undersea have not been fully explored. This study aims to investigate the scour protection effects of solidified soil considering three critical factors when applying it to OWT sites, namely cured strength, cured state, and the range of solidification. Flume tests were conducted to evaluate the impact of these factors on both local and edge scour, which is usually ignored in practice. The results indicate that optimal cured strength and state can effectively mitigate scour, with wider solidification ranges further reducing the edge scour. Additionally, three failure modes were identified: loss of solidified soil, breakage of weak solidified sections, and edge scour of solidified area. These findings emphasize the necessity for a holistic design of solidified soil parameters and construction processes. An improved analysis model was also developed to reveal the protective mechanisms of solidified soil.