Abstract

In offshore engineering, a geotechnical site investigation is an important step in analysis and design to ensure the integrity and serviceability of infrastructure. The Cone Penetration Test (CPT) stands as the prevailing technology for offshore soil characterisation. However, this test method requires a substantial allocation of resources for equipment transportation and operation personnel. This proves inefficient and costly for conducting comprehensive surveys over ocean beds. Alternatively, free-falling penetrometers (FFP) have attracted attention as a CPT replacement for soil characterisation. Nevertheless, these devices can penetrate only to shallow depths within soils, limiting their applicability for offshore site investigation purposes. A new device has been created to overcome this constraint, featuring a dynamic penetrometer launched by a speargun. Unlike conventional free-falling penetrometers, this apparatus can attain a greater penetration ratio, exceeding 20 times its diameter. The process of experimental testing yielded notable enhancements, particularly in effectively addressing challenges associated with tilting when attempting low-penetration depths. By implementing rate corrections into the methodology, promising results were obtained for equivalent static penetration resistance. This approach not only represents the capacity to influence future penetrometer designs but elevates the overall efficiency of in-situ soil characterisation procedures.