SUMMARY

Determination of soil material damping is known to be difficult and uncertain, especially in the offshore environment. Using an advanced inversion methodology based on multi-channel spectral analysis, Scholte and Love wave measurements are used to characterize sub-sea 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.

中文翻译：

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海洋环境中表面波测量的多通道分析对土壤阻尼和刚度的地震反演

概要

已知土壤材料阻尼的确定是困难且不确定的，尤其是在近海环境中。使用基于多通道频谱分析的先进反演方法，Scholte和Love波测量用于表征北海站点的海底土壤。归一化后，在遗传算法优化中使用基于行列式的目标函数来估计土壤剪切模量。尽管在近地表层获得了更高的确定性，但反向剪切模量曲线与相同数据的先前公布结果相当。半功率带宽方法用于从测量中提取衰减曲线，并基于小波压缩选择有效的参考数据点。使用改进的随机优化算法进行材料阻尼比反演。考虑到测量误差，可以从基本模式的Scholte波中高度确定地获取材料阻尼比曲线。此外，提出了一种用于从现场测量中识别材料阻尼比的频率依赖性的方法。没有发现频率依赖性的证据，可以说该地点的小应变土壤材料阻尼比与频率无关。提出了一种从现场测量中识别材料阻尼比的频率依赖性的方法。没有发现频率依赖性的证据，可以说该地点的小应变土壤材料阻尼比与频率无关。提出了一种从现场测量中识别材料阻尼比的频率依赖性的方法。没有发现频率依赖性的证据，可以说该地点的小应变土壤材料阻尼比与频率无关。