Abstract: Deep-sea sediments serve as essential bearing foundations for deep-sea engineering. However, obtaining deep-sea samples is difficult and costly, which makes it challenging to support large-scale laboratory geotechnical model tests. This study proposes a laboratory method for preparing simulated deep-sea clay based on similarity evaluation. Firstly, a small amount of original deep-sea soil is obtained, and its physical and mechanical properties are measured. Several physical and mechanical properties are then selected as similarity evaluation indices. Secondly, based on the mineral composition, grain group composition, and biological components of the original deep-sea soil, easily accessible materials are chosen as raw components. Using an improved slurry consolidation apparatus and an orthogonal experimental design, a series of samples with different material proportions is prepared. The entropy weight method is introduced to calculate the comprehensive scores of the samples, and range analysis is used to optimize the mixture design and identify key factors influencing similarity. Finally, deviation testing is conducted to verify the feasibility and effectiveness of the optimal mix ratio. Taking deep-sea clay from a water depth of 3 200 m in the northern South China Sea as the simulation target, simulation preparation tests are carried out using the proposed method. The feasibility and effectiveness of the method are further validated through dynamic mechanical property tests. The proposed approach provides a viable solution for the batch preparation of samples for large-scale indoor geotechnical model tests in deep-sea engineering, and also offers a reference for the simulation preparation of other deep-sea sediments.

Key words: deep-sea clay, deep-sea sediment, model test, sample preparation method