Relationship between shear band dilation and stress-corrected relative density under constant normal stiffness (CNS) conditions
Document Type
Article
Date of Original Version
11-15-2025
Abstract
There is an increased interest in the use of drilled and grouted micropiles as a foundation for floating offshore wind farms in deep water. Unlike onshore projects, conducting proof load tests for micropiles in offshore settings is challenging, if not impossible, necessitating improved capacity prediction methods. The objective of this study is to assess whether constant normal stiffness (CNS) testing in the laboratory can more accurately model the axial capacity of small-diameter grouted micropiles. This was accomplished by performing a series of monotonic CNS tests on samples of Monterey sand at different values of relative density, soil spring stiffness, and initial normal effective stress. The results suggest that there is a unique relationship between the amount of shear band dilation and stress-corrected relative density and that an increase in soil spring stiffness suppresses dilation. Most importantly, a conceptual framework is presented that may improve our understanding of the static capacity of drilled piles, especially micropiles that includes non-linear normal stiffness changes around the pile. Field testing including pile load testing can be used to better verify this framework.
Publication Title, e.g., Journal
Ocean Engineering
Volume
339
Citation/Publisher Attribution
Babaee, Amir, Aaron S. Bradshaw, and Christopher D. Baxter. "Relationship between shear band dilation and stress-corrected relative density under constant normal stiffness (CNS) conditions." Ocean Engineering 339, (2025). doi: 10.1016/j.oceaneng.2025.122078.