Proposing Optimized Geotechnical Investigations
Kawasaki Geological Engineering Co., Ltd. (KGE) and Chuo Kaihatsu Corporation (CKC) are leading experts in geological investigation. Leveraging our specialized technologies and extensive experience, we provide optimized survey methodologies to accurately characterize ground conditions for a wide range of infrastructure projects, including offshore wind developments.
What is a Geological Investigation?
Geological investigation, as a core component of engineering consultancy, plays a critical role in the design, construction, and maintenance of infrastructure. Given the complexity of subsurface conditions and the associated risks, the acquisition of reliable, high-quality data is essential.
Kawasaki Geological Engineering Co., Ltd. and Chuo Kaihatsu Corporation contribute to society by delivering accurate and high-quality ground data through advanced technical expertise and proven capabilities.
All the Ground Investigation Technologies You Need for Offshore Wind Construction
Click items 1–7 below for details.
１ Offshore Geophysical Exploration
Seismic Survey
Advanced Data Acquisition Technologies
Our Ultra High-Resolution Seismic (UHRS) technology, utilizing high-frequency acoustic sources, provides exceptionally detailed imaging of shallow subseafloor conditions—essential for offshore wind developments and active fault investigations. In Japan’s shallow coastal waters, both 2D and 3D UHRS surveys enable detailed visualization of complex geological structures.
Our compact survey systems can be deployed from vessels under 20 tons, enabling safe, efficient, and high-quality data acquisition even in congested coastal areas with heavy fishing activity and marine traffic.
Supporting Geological Evaluation with Ultra High-Resolution Data
Ultra High-Resolution Data obtained through UHRS technology provides precise and detailed insights into subsurface conditions, enabling reliable and accurate evaluation. In particular, 3D data enables accurate identification of subtle stratigraphic variations and fault structures that were overlooked by conventional methods.
For offshore wind developments, we deliver reliable data essential for geological risk assessment, optimized foundation design, and cable route selection.
In addition, clear and intuitive visualization of geological data supports informed decision-making throughout all project phases—from planning through construction—helping to mitigate unforeseen risks.
２ Offshore Geophysical Exploration
Seafloor Microtremor Array Survey
Seafloor Microtremor Array Survey
KGE has developed and commercialized the Seafloor Microtremor Array Survey as an effective method for estimating the depth to engineering bedrock.
This method is a geophysical survey technique based on surface-wave analysis. Seafloor seismometers are deployed in specific array configurations, such as equilateral triangles, to record microtremor data. The recorded data are then analyzed and interpreted to estimate a 1D S-wave velocity profile. The measurement takes one day per location.
Compared with conventional offshore PS logging in boreholes, this method enables more efficient surveys at a greater number of locations within a shorter timeframe and can also be applied in deeper offshore environments. By integrating this method with other investigation techniques, such as offshore boring and seismic surveys, we deliver optimized geotechnical solutions.
What is a Seafloor Microtremor Array Survey?
The ground beneath our feet is constantly vibrating at a level so small that we cannot feel it. These tiny vibrations are known as “ambient microtremors.”
Microtremors are generated by both natural phenomena, such as ocean waves, and human activities, such as transportation. By utilizing these ambient vibrations, microtremor array surveys enable the estimation of subsurface ground conditions. This technique has been widely applied on land since the 1980s.
Features of Seafloor Microtremor Sensors
KGE has developed a new Seafloor Microtremor Sensor. This sensor is a self-contained unit that houses a seismometer and a data logger within a pressure-resistant vessel. It is designed for operation at water depths of up to 200 m. As a standalone system, it does not require any cables during measurement. Its compact size allows surveys to be carried out using small vessels, enabling efficient and flexible offshore operations.
The sensor records three components of motion: two horizontal directions (X and Y) and one vertical direction (Z). These three-component measurements enable more detailed analysis and interpretation of subsurface conditions.
A next-generation model is currently under development, with an extended depth rating of up to 500 m.
３ Selection of Scaffolds to Apply Sea Area Properties
４ Various Offshore Scaffolds for Geotechnical Survey
"KEIDO-JIZAI" Marine Drilling Method
This method features the independent installation of a guide pipe at the survey location and a boring unit on a barge.
By adjusting the guide pipe length and base plate, the system can be adapted to a wide range of water depths (up to 50 m) and seabed conditions. In rough weather, the guide pipe and boring rods can be left in place, allowing for quick evacuation and rapid resumption of operations.
Key Features
Capable of drilling in deep water up to 50 m.
High mobility and allows for rapid evacuation even in adverse weather conditions.
Capable of sampling and coring from soft ground to bedrock.
Capable of performing various in-situ tests and sounding methods.
Capable of installation on inclined seabed surfaces of up to 10°.
５ Analysis Technologies for Offshore Wind
Analysis Technologies for Offshore Wind Using Geotechnical Data
Evaluating the tilt of fixed-bottom offshore wind turbines under cyclic horizontal loads induced by strong winds and high waves is a key design consideration. When performing such evaluations using numerical analysis, it is essential to employ detailed ground models capable of accurately reproducing the interaction between the wind turbine foundation and the seabed.
To fully leverage our extensive experience and accumulated expertise in geotechnical data evaluation, we are engaged in the research and development of analytical technologies that address the interaction between offshore wind turbine foundations and the seabed.
Numerical Analysis of Monopile Foundation Behavior
Wave and wind loads act on offshore wind turbines and monopiles as cyclic external forces, and their effects extend to the seabed soils surrounding the monopile.
The figure above shows the results of a numerical analysis of pore water pressure within the seabed surrounding the monopile under large wind and wave loads. The analysis shows that cyclic loading increases pore water pressure, making the seabed more prone to deformation. This may lead to the inclination of the monopile supporting the wind turbine.
What is a Monopile Foundation?
A monopile foundation is a type of foundation that supports a wind turbine using a single large-diameter pile. Its simple structure enables standardized manufacturing and efficient mass production.
６ Initiatives to Improve Operations
Enhanced Safety
In offshore geotechnical investigations, steel working platforms are commonly used, with access typically provided by fishing vessels or similar boats. Under rough sea conditions, such as high waves, boarding the platform becomes the most hazardous operation and requires utmost caution.
Previously, protective materials were installed on ladders to prevent pinching accidents; however, the risk of falling into the water still depended largely on individual capability. With the installation of a fender-equipped boarding box, transfer from the vessel has become quicker and safer, significantly reducing the risks of both pinching and falling. In addition, the boarding box provides a stable platform for workers to maintain a secure position and attach their safety harness.
Solution Enhancement
Driven by the expansion of offshore wind project areas, the demand for geotechnical investigations is growing not only in flat seabed environments but also in more challenging conditions, including sloping seabeds and uneven terrain with rocky outcrops.
In response, we have developed an innovative system equipped with a leveling attachment at the base of a steel platform, enabling stable and level installation even under these demanding conditions.
７ From Coastal Waters to Deeper Offshore Surveys
Geotechnical Investigation in Deepwater Offshore Areas
Offshore wind development is expanding from shallow waters into deepwater environments exceeding 100 m in depth. In such environments, floating wind turbines are increasingly considered as an alternative to fixed-bottom structures.
We deliver geotechnical investigations for deepwater environments. Through the continuous development and enhancement of specialized investigation equipment, we provide reliable soil parameters essential for the design of floating offshore wind facilities.
From Deepwater to Further Offshore
Future floating offshore wind projects are expected to expand into deeper waters beyond 100 m in depth. Building on our deepwater investigation expertise, we are continuously enhancing our technologies to support these more remote and challenging offshore environments.
Driven by our commitment to offshore wind development, we will continue to deliver advanced investigation solutions that contribute to a sustainable energy future.
One-Stop Geotechnical Solutions for Offshore Wind Projects
Please click the links below to visit each company’s website.
