Determination of soil material damping is known to be difficult and uncertain, especially in the offshore environment. Using an advanced inversion methodology based on multichannel spectral analysis, Scholte and Love wave measurements are used to characterize subsea soil from a North Sea site. After normalization, a determinant-based objective function is used in a genetic algorithm optimization to estimate the soil shear modulus. The inverted shear-modulus profile is comparable to previously published results for the same data, although a higher degree of certainty is achieved in the near-surface layers. The half-power bandwidth method is used for extracting the attenuation curve from the measurements and efficient reference data points are chosen based on wavelet compression. The material-damping ratio inversion is performed using a modified stochastic optimization algorithm. Accounting for measurement errors, the material-damping ratio profile is retrieved from the fundamental-mode Scholte wave with a high degree of certainty. Furthermore, a method is proposed for identifying the frequency dependence of the material-damping ratio from in situ measurements. No evidence for frequency dependence is found and the small-strain soil material-damping ratio at this site can be said to be frequency independent for the measured conditions.@en

Soil stiffness and damping parameters are important to correctly model the structural response and energy dissipation, especially for embedded and lightly damped structures. This research aims to demonstrate that multichannel analysis of surface wave (MASW) techniques can be used to generate a reliable in-situ measurement of the soil damping in marine environments. The goal of the project is to refine and apply a reliable method which is able to estimate the soil stiffness and damping profile in the depth range of 0-30m. Love waves, which are rarely used for surface wave applications and to the author’s knowledge never used for a damping inversion from real surface waves measurements, are included in this analysis. The frequency content of the present dataset is lower than previous investigation, which is important for extrapolating the damping parameters to the even lower frequency range of relevance for structural models. Finally, it is proposed a novel technique for retrieving the frequency dependence of the material damping by using on-site collected data.@en

Soil stiffness and damping parameters are important to correctly model the structural response and energy dissipation, especially for embedded and lightly damped structures. This research aims to demonstrate that multichannel analysis of surface wave (MASW) techniques can be used to generate a reliable in-situ measurement of the soil damping in marine environments. The goal of the project is to refine and apply a reliable method which is able to estimate the soil stiffness and damping profile in the depth range of 0-30m. Love waves, which are rarely used for surface wave applications and to the author’s knowledge never used for a damping inversion from real surface waves measurements, are included in this analysis. The frequency content of the present dataset is lower than previous investigation, which is important for extrapolating the damping parameters to the even lower frequency range of relevance for structural models. Finally, it is proposed a novel technique for retrieving the frequency dependence of the material damping by using on-site collected data.@en

Soil stiffness and damping parameters are important to correctly model the structural response and energy dissipation, especially for embedded and lightly damped structures. This research aims to demonstrate that multichannel analysis of surface wave (MASW) techniques can be used to generate a reliable in-situ measurement of the soil damping in marine environments. The goal of the project is to refine and apply a reliable method which is able to estimate the soil stiffness and damping profile in the depth range of 0-30m. Love waves, which are rarely used for surface wave applications and to the author’s knowledge never used for a damping inversion from real surface waves measurements, are included in this analysis. The frequency content of the present dataset is lower than previous investigation, which is important for extrapolating the damping parameters to the even lower frequency range of relevance for structural models. Finally, it is proposed a novel technique for retrieving the frequency dependence of the material damping by using on-site collected data.@en