At the 22nd Kanto Branch Presentation of the Geotechnical Society of Japan (GeoKanto2025) held on November 6, 2025, graduate student Sosuke Ono, undergraduate students Shunsuke Ota, Konoha Shimizu, and Satoshi Narita from our university received the Outstanding Presenter Award.

【Winner】
Sosuke Ono (Graduate School of Marine Science and Technology Master's Program1Years　Course of Marine Resources and Environment）
Shunsuke Ota (4th year student, Department of Marine Resources and Energy, Faculty of Marine Resources and Environment)
Konoha Shimizu (4th year, Department of Marine Resources and Energy, Faculty of Marine Resources and Environment)
Satoshi Narita (4th year, Department of Marine Resources and Energy, Faculty of Marine Resources and Environment)

[Title and content of award-winning research]
Sosuke Ono
Title: Development of a submarine-seated surface CPT for laying submarine cables
In recent years, the development of offshore wind power generation facilities has seen growing demand in Japan. The laying of submarine cables to transmit generated electricity to shore requires mechanical information on the soil 1–2 m below the seabed surface at the installation site. Currently, soil surveys are conducted using columnar sampling and thrust probe testing, but these methods have limitations in deep waters. There is also a movement to introduce the cone penetration test (CPT), which is widely used in Europe, but penetration devices that can be used underwater are not manufactured in Japan, and bringing them from overseas requires significant manufacturing and transportation costs. Therefore, we developed a low-cost, highly efficient penetration device. We outlined the device under development and presented the results of a field test conducted at Kitashimoura Fishing Port in Kanagawa Prefecture in April 2025.

Shunsuke Ota
Title: Pull-out model experiment of flat anchor in sand
Japan has positioned offshore wind power generation as a key priority in its quest to achieve carbon neutrality by 2050. As an island nation, the introduction of floating offshore wind turbines is particularly anticipated. Many anchor types have been proposed for floating offshore wind turbines, one of the key technologies. Among these, flat anchors are characterized by their lightweight design, high holding power, and low manufacturing cost. This study explored the application of flat anchors. As a first step toward elucidating the mechanism by which flat anchors exert their holding power, we conducted pull-out model experiments on flat anchors installed with a relatively shallow embedment ratio (embedding depth H / anchor width B < 3) in medium-dense (relative density Dr = 70-85%) sand. To investigate the sensitivity of H/B, we compared the load exerted by the end of the pull-out period. We also compared the experimental data with the anchor coefficient prediction formulas proposed in previous literature.

Shimizu Konoha
Title: Experimental observation of seismic behavior of mooring anchors buried in sandy soil
In recent years, with the increasing demand for renewable energy toward the realization of a decarbonized society, technological development of floating offshore wind power generation has been promoted as a power generation method that can be introduced even in deep waters. When introducing this power generation method in earthquake-prone regions, including Japan, a key issue is the stability of the mooring anchors that secure the floating structure to the seabed to maintain its position during an earthquake. In this study, vibration experiments were conducted to observe the behavior of mooring anchors due to earthquakes and ground liquefaction, focusing on (1) the magnitude of holding force and (2) the type of anchor. In the experiments, three types of anchors—gravity, plate, and suction bucket—were installed in sandy soil and subjected to vibration in a 50 g centrifugal acceleration field.

Satoshi Narita
Title: Rheological properties of ore-lifting carrier materials and their time-dependent changes
In the development of seabed mineral resources, ore lifting technology using a carrier material circulation system using capsule transportation is being considered. Bentonite mud is a promising carrier material because it combines transportability and retention properties. However, issues remain, such as the unknown change in viscosity over time and the lack of consideration of the influence of blending in the study of scaling laws in ore lifting model experiments. Therefore, with the long-term use of the carrier material and its use in experiments in mind, we evaluated the effect of the number of days since the preparation of bentonite mud on its rheological properties (shear stress versus strain rate and apparent viscosity) using viscosity measurements. Using the results, we considered the relationship between viscosity and time, and the relationship between consistency coefficient and mass concentration in the rheological properties.

From left in the photo) Associate Professor Nomura Shun, Mr. Ono, Mr. Narita, Mr. Shimizu, Mr. Ota, and Professor Takahashi Hideki

<Related links>
Japan Geotechnical Society
Geotechnical Society of Japan Kanto Branch
GeoKanto2023, Geotechnical Society of Japan Kanto Branch Presentation
GeoKanto2025report