Offshore energy production increases rapidly on the Finnish west coast. Effective ground investigation methods are needed for offshore wind farm construction and cable route planning. This study identified fine-grained local subsurface sediment units based on seismoacoustic survey and sediment coring complemented with geotechnical properties from free fall cone penetrometer tests. The finegrained sediments in the study area consist of brackish-water mud, postglacial lacustrine clay and glaciolacustrine clay and silt which all show variability in physical properties and undrained shear strength profile. The study shows that free fall penetrometer tests provide a ground-truth for the seismoacoustic profile interpretation and, combined with seismoacoustic survey and sediment coring enable a fast and cost-efficient site reconnaissance.@en

This paper proposes a numerical framework to simulate in-situ free fall cone penetration tests conducted on soft and sensitive marine clay. First, the free fall cone penetration tests are carried out at an offshore site in the northern part of the Gulf of Finland, Baltic Sea. The numerical simulation employs the Generalized Interpolation Material Point Method to replicate the process of indentation of the cone penetrometer into the clay. The clay is modelled using an advanced constitutive model that considers the effect of strain rate and strain softening associated with the dynamic penetration process. The simulation uses a friction contact model to represent the interface between the cone penetrometer and the clay. The numerical simulation accurately replicates the penetration process associated with the tests. @en