Seismic inversion of soil damping and stiffness using multichannel analysis of surface wave measurements in the marine environment

Seismic inversion of soil damping and stiffness using multichannel analysis of surface wave measurements in the marine environment

Armstrong, Michael (Siemens Gamesa Renewable Energy)
Ravasio, Matteo (Siemens Gamesa Renewable Energy)
Versteijlen, W.G. (Siemens Gamesa Renewable Energy)
Verschuur, D.J. (TU Delft ImPhys/Computational Imaging)
Metrikine, A. (TU Delft Offshore Engineering; TU Delft Engineering Structures)
van Dalen, K.N. (TU Delft Dynamics of Structures)

Engineering Structures

2020

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.

Elasticity and anelasticity
Inverse theory
Controlled source seismology
Guided waves
Seismic attenuation
Surface waves and free oscillations

http://resolver.tudelft.nl/uuid:794a4a22-df06-4883-82d3-f9fbaaf794bc

https://doi.org/10.1093/gji/ggaa080

0956-540X

Geophysical Journal International, 221 (2), 1439–1449

Institutional Repository

journal article

© 2020 Michael Armstrong, Matteo Ravasio, W.G. Versteijlen, D.J. Verschuur, A. Metrikine, K.N. van Dalen