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| 宽级配土落雨法制模的离析分层试验分析及数值模拟 |
| Experimental Analysis and Numerical Simulation of Segregation Stratification in Wide-Graded Soil Prepared by Pluviation Method |
| 投稿时间：2025-04-24 修订日期：2025-06-05 |
| DOI： |
| 中文关键词: 宽级配土 落雨法 分层现象 物理机制 落速 PFC3D |
| 英文关键词:wide-graded soil pluviation method sand layering phenomenon physical mechanism falling speed PFC3D |
| 基金项目:济南大学科技计划项目(XKY2062,XBS2011)；黑龙江省自然科学基金资助项目(LH2023E019) |
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| 中文摘要: |
| 落雨法能够模拟地基土体自然沉积过程且令模型获得与天然地基最为近似的力学特性,是一种常用的岩土模型制备方法。在落雨法制备宽级配土模型时,常出现分层与扬尘现象,对模型的均匀性与试验结果可靠性造成不利影响。针对上述问题,本文建立单颗粒和颗粒簇力平衡方程,分析了宽级配土的分层与扬尘机制；基于PFC3D离散元,开展了宽级配土下落分层现象和和扬尘数值模拟,揭示了环境介质和级配宽度等因素的影响规律。结果表明：分层现象主要由不同粒径颗粒在非真空环境中的下落速度差异引起；随着环境介质密度、粘滞系数与颗粒级配宽度的增加,试样分层现象趋于明显；扬尘现象主要归因于细颗粒在环境流体扰动下的较低落速与长期悬浮,细颗粒含量越高,扬尘现象越明显；颗粒簇在下落过程中与环境流体的相互作用导致截面扩展,从而扩大扬尘范围；截面扩展速率随落距的增大而减小,并趋近于0。本研究成果可为深入理解落雨法分层与扬尘机制,提高含细粒的宽级配土地基模型制备质量提供有效理论依据和参考 。 |
| 英文摘要: |
| The pluviation method is a commonly used geotechnical model preparation technique that simulates the natural deposition process of foundation soils, allowing the model to achieve mechanical properties most similar to those of natural foundations. During the preparation of wide-graded soil models using the pluviation method, stratification and dust-raising phenomena often occur, adversely affecting the uniformity of the model and the reliability of the experimental results. To address these issues, this paper establishes the force balance equations for individual particles and particle clusters to analyze the stratification and dust-raising mechanisms of wide-graded soil. Based on PFC3D discrete element modeling, numerical simulations of the stratification and dust-raising phenomena in wide-graded soil deposits are conducted, revealing the influence patterns of factors such as environmental media and gradation width. The results show that the stratification phenomenon is primarily caused by the differences in settling velocities of particles with different sizes in non-vacuum environments. As the density, viscosity, and particle gradation width of the environmental medium increase, the stratification phenomenon becomes more pronounced. The dust-raising phenomenon is mainly attributed to the lower settling velocity and prolonged suspension of fine particles under the disturbance of the environmental fluid. The higher the content of fine particles, the more significant the dust-raising phenomenon. During the descent of particle clusters, interactions between the particles and the surrounding fluid cause cross-sectional expansion, thus increasing the dust dispersion range. The rate of cross-sectional expansion decreases with increasing fall height, eventually approaching zero. The findings of this study provide effective theoretical support and references for a deeper understanding of the stratification and dust-raising mechanisms in the pluviation method and for improving the quality of wide-graded soil foundation models containing fine particles. |
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