Objective Marine geotechnical investigation provides an important parameter basis for the design of offshore wind power foundation, which is the key to the safety and stability of offshore wind power foundation. In recent years, China's offshore wind power industry has developed rapidly. However, China has not yet established a refined standard marine investigation method.

Method Based on an offshore wind power project in sea areas of Eastern Guangdong, this paper proposed an idea of refined investigation for marine soils, and initially established a complete set of methods for refined geotechnical investigation of offshore wind power projects. This method covered many aspects such as desktop study of existing investigation data, scheme of field investigation, scheme of laboratory geotechnical tests and evaluation of intact soil sample quality.

Result The core idea of the method includes three parts: firstly, make full use of surrounding investigation data to optimize the schemes of geotechnical investigation and bore-hole, improve the investigation efficiency and reduce the investigation cost. Secondly, the strata are divided by the geological conditions revealed by CPT. At the same time, combined with the results of CPT and the foundation type of wind turbine, a refined geotechnical test scheme is developed. Thirdly, pay attention to the quality of the intact soils, reproduce the in-situ state of soil as much as possible, and mutually correct the interpretation results of laboratory geotechnical tests and in-situ CPT tests to improve the accuracy and integrity of geotechnical design parameters.

Conclusion The proposal of the refinement geotechnical investigation method of offshore wind power is of great significance to the establishment of a standardized database for geotechnical investigation in the South China Sea.