Feature Stories

Developing a Green Offshore Foundation Concept

hande gerkus

Gerkus is helping the research team with the design as well as the lab and field testing of a deepwater anchor which could facilitate the development of more sustainable foundation concepts.

Ph.D. student Hande Gerkus left her native Turkey to come to UT Austin to work on the design of a new sustainable offshore foundation system for offshore wind turbines. Her work is advancing a fundamental understanding of soil-structure interactions to develop the Flying Wing Anchor, a steel plate in the shape of an aerodynamically efficient winged aircraft.

The research plan on this NSF-funded project, “Green Foundation for Green Energy”, encompasses a comprehensive approach to physically testing scale models of a Flying Wing Anchor during penetration and in-service loading and numerically modeling the 3D behavior with time of the anchor with the Finite Element Method (FEM) and advanced constitutive models.

The Geotechnical Engineering program at UT Austin is considerably experienced in offshore model testing. Based on the results of completed projects which have tested different anchor models, Professor Bob Gilbert, the Principal Investigator, and his team are coming up with a new design. Gerkus is designing and testing the new offshore anchor model in the lab and field, working alongside Ph.D. student Eugenio Itturiaga and undergraduate Jani Vilkki (senior).

The motivation for this research is to inspire and facilitate a viable green foundation concept for the generation of renewable energy from offshore wind turbines.  Conventional offshore foundations tend to be inefficient and not very sustainable. Many feel that the future of offshore wind is in deep water, where wind resources are abundant, turbine size can be maximized, and facilities can be located relatively near major cities without being an eyesore.

The challenge in deep water is the required effort and significant cost for facility construction. This research aims to reduce the economic and environmental cost of harnessing offshore wind energy, which is a key challenge to increasing the availability of renewable energy.

The new anchor would be installed using gravity from free fall through the water column and penetration into the sea floor.  Tension in the line that attaches the wind turbine structure to the anchor causes the anchor to dive and pitch toward the horizontal in service, thus maximizing the available holding capacity in bearing over the full wing surface in an extreme load.

“When the geometry and the engineering properties of the anchor model is ready,” says Gerkus, “we will continue testing it in the lab in different clay soils and will modify the design based on lab performance. Finally we will test it in the field. So from the beginning to the end, we are designing a new model with three other prestigious universities.

For this project, The University of Texas at Austin is working in collaboration with the University of Rhode Island, University College Dublin, and Queen’s University Belfast. Their shared objective is to advance fundamental understanding of the interactions between a wing-shaped plate, the line loading the plate, and the soil around the plate and the line.

“It is very exciting to be a part of a multi-disciplinary project,” she says. “I have the opportunity to learn about different engineering applications and work with people from other disciplines which helps broaden my scope.”

Gerkus helps analyze the results of UT Austin’s model test facilities which conduct penetration tests in clay. The test facility utilizes two types of clay: kaolinite, due to its relatively high coefficient of consolidation; and marine clay from the Gulf of Mexico. Tests will be conducted in a variety of soil profiles at UT Austin (clay) and University of Rhode Island (sand).

The demonstration testing in the U.S. will be performed in the Northeast at two offshore sites that are also sites for future wind projects – the Block Island Wind project and the Cape Wind project.  The anchors will be deployed and tested by a small research vessel.

The Flying Wing Anchor concept has the potential to be used in various applications beyond floating offshore wind turbines including guyed fixed-bottom wind turbines, devices to generate marine renewable energy from current and waves, as well as floating bridges. More fundamentally, the principle of “installing” itself could potentially be applied to conventional onshore structures if the structural system is designed to complement the foundation system by properly distributing load.

This research provides unique opportunities for all students involved. Gerkus, a doctoral candidate, is naturally thrilled to be a part of the Flying Wing Anchor project.

“I became a civil engineer just because I was curious about how structures are built,” says Gerkus. “So I decided to learn it and found the geotechnical aspect the most interesting.”

She received her M.S. degree in Geotechnical Engineering and B.S. degree in Civil Engineering at Istanbul Technical University. During her early graduate education, she worked in practice and then as a research assistant for the Istanbul Technical University. She began the pursuit of a doctoral degree with a Fulbright Scholarship and chose the CAEE program at UT Austin because of its international prestige.

“Civil Engineering at UT has a really good reputation all around the world due to successful professors who are experts in different research areas, highly-motivated graduate students with strong backgrounds, broad research topics, and well-equipped research facilities,” she says. “Who would not want to study in a department like this?”

 “I appreciate the opportunity to learn about different topics from professors who are experts in their areas and I like being able to work with great friends on complicated research projects,” she says. “I should also mention that the administrative and technical staffs are always helpful and friendly.”

Gerkus is an active member of Geo-Institute UT Austin and enjoys organizing academic and social events with other graduate students.

She likes that Austin is a small city compared to Istanbul and that it is always sunny. In her spare time, she plays volleyball with friends, swims or runs around the lake. The city’s many music festivals, cafes and bars are also attractive.

She will join the geotechnical engineering faculty in Istanbul Technical University after graduation.