# Characteristics of the Damping Ratio of Undisturbed Offshore Silty Clay in Eastern Guangdong, China
## 1 Introduction
[17] investigated the damping of sandy and silty soils, concluding that particle shape, grain-size distribution, and silt content significantly influence the damping of non-plastic soils. [PERSON] et al. [18] conducted experimental studies on silty clay and found that the Ramberg-Osgood function accurately predicts the damping ratio at small-to-medium strains but overestimates it at large strains. Focusing on soils in China's offshore regions, [PERSON] et al. [19] indicated that the damping characteristics of silty clay are broadly similar between continental and marine deposits,  
Figure 1: Scaling of soil–pile interaction damping from damping response measured at soil element level. where as silt and fine sand show significant differences between the two depositional environments. [PERSON] et al. [20] compiled 372 sets of dynamic nonlinear soil parameters from the dynamic triaxial tests in seismic safety reports for nearly 40 offshore oil platforms in the Bohai Sea. The soils tested included silty clay, silty fine sand, silt, sandy silt, and silty fine sand, and they provided only recommended damping ratio values. Using cyclic triaxial tests, [PERSON] et al. [21] investigated the damping ratios of offshore silty clay, silt, silty sand, and sand in the Yellow Sea off Jiangsu Province. Compared to Bohai Sea soils, their results revealed marked differences in damping ratio characteristics across different marine regions. Using dynamic triaxial tests, [PERSON] et al. [22] conducted a preliminary study on silty clay from the Eastern Henan Plain under medium-to-high strain levels and observed that the damping ratio increases with higher confining pressure. By performing resonant column tests, [PERSON] et al. [23] studied the small-strain damping of soils from Liaodong Bay and found that, at the same strain levels, marine soils have a lower damping ratio than terrestrial soils. [PERSON] et al. [24] reviewed and analyzed China's recent studies on soil damping ratios and noted several issues, including insufficiently detailed soil classifications, inconsistencies in testing instruments and data-processing methods, and weak correlations between results and fundamental soil properties. In summary, most existing research on soil damping has focused on clay and sand, with relatively few studies addressing silty clay. Silty soils, which lie between clay and sand in terms of particle composition, exhibit complex mechanical behavior. Therefore, the damping characteristics of clay or sand cannot be directly applied to silty soils. Given the widespread occurrence of silty soils along China's coasts, targeted studies on the damping ratios of typical silty soils are crucial. This paper presents an experimental study on the damping ratio characteristics of representative silty clay from an offshore wind farm in eastern Guangdong. Resonant column and cyclic direct simple shear tests were conducted to measure the damping ratio across the full strain range, and the results were compared with predictions from widely used empirical models. The findings not only expand the database of damping ratios for typical silty clays in China's offshore regions but also provide valuable insights for seismic engineering and structural optimization in offshore wind power projects.