Numerical simulation analysis of low-disturbance sampling process for saturated soft clay sediments on the seabed

Abstract:

Marine sediments serve as crucial repositories of oceanic information， and the accurate acquisition of undisturbed samples is essential for marine resource exploitation. Sampling is the primary method to obtain sediment samples， and its precision exerts a significant influence on resource exploration and analysis. Thus， acquiring low-disturbance soil samples constitutes the core objective of sampling operations. This study addresses the issue of soil disturbance during the drilling and sampling of submarine saturated soft clay. A three-dimensional numerical model of the sampler-soft clay interaction was established using Abaqus software with the Coupled Eulerian-Lagrangian （CEL） algorithm to systematically investigate the influence of the cutting shoe angle and penetration velocity on soil disturbance. Initially， sampler models with cutting edge angles of 5°， 10°， 15°， 20°， and 25° were adopted to analyze the effect of the cutting edge angle on soil disturbance and determine the optimal angle. Subsequently， various penetration velocities were simulated to further study the degree of soil disturbance under different velocity conditions. The results indicate that as the cutting edge angle increases， the disturbance range of the soil outside the sampling tube expands gradually， and the overall disturbance range of the samples inside the tube increases accordingly； compared with the 25° cutting edge angle， the 5° angle improves the sample recovery rate by approximately 4%. Furthermore， a higher penetration velocity results in a lower degree of soil disturbance： in comparison with 20 mm/s， a penetration velocity of 45 mm/s reduces the strain influence range of the soil on the inner tube wall by 34% and the maximum strain value by 11.2%. The combination of a small cutting edge angle and a high penetration velocity can effectively inhibit the plastic flow and structural damage of the soil. These findings provide a solid theoretical basis for the design of low-disturbance samplers and the selection of operational parameters for the sampling of submarine saturated soft clay sediments.