Design and experimentation of self-contained digital cone for deep sea

Seabed soil properties play an essential role in a wide range of marine engineering applications. This study presents the design of a distinctive self-contained cone that is in line with international standards and suitable for deep-sea operations. This design aims to address and overcome the current limitations faced by cone penetration testing probes, such as problems related to rod connections and signal attenuation. An inclination-based posture correction algorithm was introduced to obtain vertical penetration displacement. Additionally, a calibration curve was established between applied load on the probe and the recorded strain gauge signal. Based on theoretical calculations and finite element simulation experiments, an analysis and research were carried out on the impact of deep-sea environmental factors, such as high-pressure environments and seal ring friction, on penetration survey results. Simultaneously, a tidal flat test was performed. By comparing the data collected by the probe with that of the vane shear test, the accuracy of the probe was verified. In the final implementation stage, the cone was introduced to a specially designed CPT station in the South China Sea. The obtained geotechnical parameters largely corresponded with the previously examined strata characteristics, confirming the cone's reliability and effectiveness for in-situ survey work in deep-sea environments.