Research on Undrained Shear Strength Rate Properties of Shallow Soft Clay in an Offshore Wind Farm in Shandong Province

For understanding the variations of the response of seafloor soft clay strength to different loading rates, the non-drainage shear strength characteristics of seafloor shallow soft clays in an offshore wind farm area in Shandong are tested and analyzed under various shear rates by using a high-precision soft-solid rheometer. The results show that the shear rate does not affect the characteristics of the non-drainage shear stress-strain relationship of seafloor soft clays. Under different shear rates, the initial non-drainage shear strength of all seafloor soft clays shows strain-softening collapse characteristics, while the remodeling non-drainage shear strength shows plastic collapse features. There is a positive correlation between the peak non-drainage shear strength of seafloor soft clays and the shear rate, whereas the residual non-drainage shear strength is almost not affected by the shear rate. Under different conditions, the average residual strength is about 1 700 Pa. The sensitivity of seafloor soft clays trends to increase slowly with the increase of the shear rate. The results of the study can provide a reference for selecting reasonably the strength parameters of seafloor soft clays under different loading rates in marine engineering.