Efficient Preparation of Uniform Saturated Marine Clay via a Combined Vacuum–Capillary Technique

Model testing is an important method for investigating the interaction between marine structures and soil, and the preparation of high-quality saturated clay samples plays a crucial role in laboratory testing. In this study, a new method for preparing saturated soil samples was developed by combining vacuum extraction and permeation saturation, and its performance was validated through laboratory experiments. A series of laboratory tests, including the gravity and cutting-ring methods, was conducted on columnar soil samples to evaluate the impact of this new technique on soil properties. The results indicate that the soil samples prepared using the new method achieved saturation levels of at least 97% and spatial uniformity. In addition, a large-volume saturated clay sample preparation method was designed and experimentally validated specifically for large-scale model tests. Soil samples were prepared in a model box with dimensions of 300 mm (Lrec) × 300 mm (Wrec) × 200 mm (Drec) in 24–48 h. Both the T-bar penetration and vane shear tests were performed on the prepared soil samples to measure their undrained shear strength. The results show that the middle and lower layers of the large-volume soil samples exhibited spatial uniformity.