| 摘要: |
| 伴随土工离心试验的应用拓展与量化需求的提升，试验模型孔隙率、均匀性的精确控制与影响因素，成为目前土工离心试验技术发展的重要课题之一。砂雨法作为土工离心试验常用制模方法之一，因其制备过程与天然粗粒土地基形成过程相似、颗粒不易破碎、制样密实度范围较宽等特点被广泛应用。为认识砂雨法制备模型孔隙率的控制因素与影响规律，基于PFC3D离散元分析软件，建立了砂雨法成型过程数值模拟方法，通过探讨落距、筛孔粒径比、环境介质等因素影响规律及与已有认识进行对比，论证了数值模拟分析方法的可行性。结果表明：制备模型孔隙率与落距呈负相关性，孔隙率随落距增大而减小且趋势逐渐变缓；孔隙率与筛孔粒径比呈正相关性，孔隙率随筛孔粒径比增大而增大；孔隙率与环境介质密度呈负相关性且影响显著，模型表面水层对孔隙率起主导控制作用。研究成果与结论，对进一步研究砂雨法因素耦合机制与综合参数选取，具有指导意义与借鉴价值。 |
| 关键词: 砂雨法 孔隙率 控制因素 离散元 环境介质 PFC3D |
| DOI： |
| 分类号:TU41???????????? |
| 基金项目:中国地震局工程力学研究所基本科研业务费专项资助项目(2019EEEVL0203)；国家自然科学基金项目(51609218)；黑龙江省自然科学基金项目(YQ2019E035) |
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| Study on feasibility of PFC3D-based numerical simulation for sample reconstitution using sand pluviation |
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Wang Haoran1, Wang Yongzhi1, Wang Hai2, Tang Zhaoguang1, Wang Tiqiang1
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1.Key Laboratory of Earthquake Engineering and Engineering Vibration, Institute of Engineering Mechanics, China Earthquake Administration;2.School of Water Conservancy and Environment, University of Jinan
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| Abstract: |
| With the increasing application of geotechnical centrifuge model tests and the increasing demand of quantitative analysis, influencing factor and precise control of sample preparation on void ratio and void distribution have arisen as a key issue in the development of geotechnical centrifuge modeling techniques. Sand pluviation is an important technique for preparing sand models and widely employed in geotechnical centrifuge modeling, due to the process of its reconstitution similar to the formation of natural coarse sand strata and the advantages of avoiding soil grain crushing and achieving a wide range of relative density. In order to understand the effect of control factors on void ratios of samples prepared by sand pluviation, a discrete element method based on PFC3D is established to simulate the process of sample reconstitution using sand pluviaiton. Through discrete element simulation of the effect of drop height, mesh-grain size ratio, environmental medium, the feasibility of the proposed discrete element method is properly validated with the general knowledge from physical model tests. The results show that the void ratio and the drop height appear in an obvious negative correlation, and the rate of decreasing in the void ratio gradually attenuates with the increase of drop height. Meanwhile, a positive correlation exists between the mesh-grain size ratio and the void ratio, and the latter is found to distinctly increase with the increasing of the former. The density of environmental medium is exhibited in a significant negative correlation with the void ratio and has an important influence. Consequently, the layer thickness of model surface water plays a leading role in the control of the void ratio. The research method and results provide useful guidance for control factor selection and understanding formation mechanism of sand pluviation techniques and has practical significance. |
| Key words: sand pluviation void ratio control factor discrete element environmental medium PFC3D |
