The offshore wind energy sector requires efficient and environmentally conscious installation of founda-tion piles. Impact-hammering generates significant noise pollution, requires mitigation measures, andcan cause pile fatigue, while vibro-hammers face limitations in achieving target depths in dense soils. This thesis investigates the technical feasibility of applying the GBM Works Vibrojet® – a new method combining vibro-hammering with water jetting near the end of the pile to fluidize internal soil and reduce friction for installing small-diameter piles (0.5-4 meters) used in jacket structures and floating windturbine foundations.

The study employs literature reviews, adapts existing soil resistance (SRD) and bearing capacity (API) models, and introduces a ”Vibrojet® potential reduction ratio” to quantify the resistance of the soil inside the pile, which can potentially be reduced to zero. It analyses various pile dimensions and soil conditions representative of the North Sea. Findings suggest the Vibrojet® can likely be scaled down for small-diameter piles, although submerged installation and the soil plugging effect, for piles with a diameter smaller than 1.5 meters, need further study. The potential reduction in the resistance of the soil in the pile is comparable to monopiles for unplugged small-diameter piles but significantly higher for plugged piles. Consequently, the impact of the Vibrojet® on the axial bearing capacity in comparison to impact-hammering is similar to that of monopiles (20-25% reduction) in the analysed non-uniform soil conditions for unplugged piles, but can be substantially higher for plugged piles, particularly shorter ones.

The study concludes that installation by the Vibrojet® has technical feasibility for small-diameter piles, offering significant soil resistance reduction potential, especially in plugged conditions. While the bearing capacity reduction for unplugged piles is manageable, the impact on plugged piles requires careful design consideration, particularly given the axial loading demands on jacket and mooring piles. Recommendations include using more advanced CPT-based models, conducting physical tests, and further investigating the precise effects of fluidization on soil properties and bearing capacity. ... Read more

The report tackles Galveston's flooding challenges, which are currently in development with the US Army Corps of Engineers (USACE) ring barrier. However, the current design, predominantly addressing coastal flooding, falls short in dealing with pluvial flooding, relying heavily on pumps. This top-down approach neglects environmental and stakeholder considerations, resulting in a decoupled response to compound flooding, lacking adaptability, and overlooking the impact of chronic flooding on local businesses. The central research question revolves around reshaping the Galveston ring barrier in The Strand area for enhanced functionality against both coastal and pluvial flooding, sustainable management of catastrophic and chronic flooding, and improved public space value. The methodology consist of a literature review, fieldwork in 'The Strand,' stakeholder engagement in Texas, the design of multiple alternatives that deal with the issue at hand and evaluation through a Multi-Criteria Analysis. Two alternative designs, sensitive to identified issues, are presented for the Strand area. The outcome emphasizes an interdisciplinary approach incorporating the knowledge of the different academic backgrounds of the team, with designs adaptable for broader implementation in Galveston.
The design alternatives centres on measures to counteract flooding, specifically cloudburst roads, retention areas, and a promenade. Caution is advised in interpreting results, emphasizing the need for further investigation into hydraulic conditions. Climate change effects are underscored, considering sea level rise, precipitation rates, and increased hurricanes. The project area, focusing on a 1 km stretch, offers local adaptation measures, with potential extension to larger areas to explore system behaviour on a larger scale. The study notes the uncommon implementation of sustainable drainage systems in the United States,
highlighting the importance of addressing common failure causes such as incomplete knowledge and poor communication. While two measures for pluvial flooding are examined, the report suggests a more detailed design should consider additional factors like green roofs and their impact on runoff speed and drainage capacity. ... Read more