海底饱和软黏土沉积物低扰动取样过程数值模拟分析

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

摘要:

海底沉积物作为海洋信息载体，准确获取其原状数据对资源开发至关重要。取样是获取沉积物的关键手段，取样的精准度对资源勘探与分析有着极大影响，获取低扰动土体样品是取样工作的核心要点。本文针对海底饱和软黏土钻进取样过程中土体扰动问题，基于Abaqus软件，采用耦合欧拉-拉格朗日（CEL）算法，建立取样器-软黏土相互作用三维数值模型，探究取样管切削角和贯入速度对土体扰动的影响规律，先采用刃口角度为5°、10°、15°、20°、25°的取样器模型，分析刃口角度对土体扰动的影响，确定最优刃口角度，随后设置不同取样管贯入沉积物的速度，进一步研究不同贯入速度下土体的扰动程度。结果表明：随刃口角度增加，取样管外部土体扰动范围逐步增大，管内样品整体扰动范围也随角度增加而增大，刃口角度为5°时相比于25°，样品采取率提升了约4%；贯入速度越高，土体扰动程度越低，45 mm/s相比20 mm/s，管内壁土体应变影响范围缩小34%，管内壁最大应变值降低11.2%；小刃口角度与高贯入速度的组合可有效抑制土体塑性流动与结构破坏。研究成果为海底饱和软黏土沉积物低扰动取样器设计与施工参数选取提供了理论支撑。

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.