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Journal of ZheJiang University (Engineering Science)  2023, Vol. 57 Issue (7): 1382-1392    DOI: 10.3785/j.issn.1008-973X.2023.07.013
Development and performance study of water uptake-able model root based on osmotic technique
Jun-jian ZHAO1,2(),Teng LIANG1,*(),Liang-tong ZHAN1,2,Kwan LEUNG ANTHONY3,Yan-bo CHEN1,Yu ZHAO1,2,Yun-min CHEN1,2
1. Center for Hypergravity Experimental and Interdisciplinary Research, Zhejiang University, Hangzhou 310058, China
2. Institute of Geotechnical Engineering, Zhejiang University, Hangzhou 310058, China
3. Department of Civil and Environmental Engineering, Hong Kong University of Science and Technology, Hong Kong 999077, China
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A new 3-D printed water uptake-able model root based on osmotic technique was designed and manufactured in order to simulate the effects of water uptake by real plant roots and its influence on hydrological and mechanical properties of the surrounding soil. The model root was designed with a perforated hollow structure and wrapped with a semi-permeable membrane. Water was absorbed from soil by the osmotic pressure gradient between PEG solution and soil water when filled with polyethylene glycol (PEG) solution inside. Results of 1-g water uptake tests in silty clay with sand showed that circulating PEG solution with a concentration equivalent to an osmotic pressure of 1500 kPa produced a maximum soil matric suction of approximately 120 kPa near the model root, overcoming the suction inducing limit of existing water uptake-able model root using vacuum technique. The model root could possess varied water uptake potential, hence simulate different evaporation scenarios through adjusting the molality of solute PEG within proper range and controlling solution circulating properties.

Key wordssoil bioengineering      soil matric suction      model root      osmotic technique      3D-printing technique     
Received: 19 July 2022      Published: 17 July 2023
CLC:  TU 43  
Fund:  国家自然科学基金资助项目(41961144018, 52008368, 51988101, 51922112);香港研究资助局项目(C6006-20G)
Corresponding Authors: Teng LIANG     E-mail:;
Cite this article:

Jun-jian ZHAO,Teng LIANG,Liang-tong ZHAN,Kwan LEUNG ANTHONY,Yan-bo CHEN,Yu ZHAO,Yun-min CHEN. Development and performance study of water uptake-able model root based on osmotic technique. Journal of ZheJiang University (Engineering Science), 2023, 57(7): 1382-1392.

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为了模拟自然植物根系的吸水过程,探究其对周边土体水文力学特征的影响机制,利用3D打印技术,设计并制造基于正渗透原理的新型可吸水模型根系. 模型根系采用中空结构,侧壁开孔,外覆半透膜. 当内部灌注聚乙二醇(PEG)溶液时,PEG溶液和土中水分间存在的渗透压梯度驱使了模型根系吸水. 常重力模型根系吸水试验结果表明,在含砂粉质黏土中,循环浓度等效1500 kPa渗透压的PEG溶液可在根系附近土体中产生最大约120 kPa的基质吸力,该基质吸力超过了真空法模型根系的理论最大产生吸力. 通过在适当范围内调整PEG溶液的质量摩尔浓度,并控制溶液循环特征,模型根系可以具备不同的吸水能力,从而模拟不同的现实工况.

关键词: 生态岩土工程,  土体基质吸力,  模型根系,  渗透原理,  3D打印技术 
Fig.1 Calibration result of molality-Brix relationship for PEG 20 000 solution
Fig.2 Overview of newly-developed 3D-printed model root
Fig.3 Particle size distribution curve of test soil
项目 参数 实测值
基本土性参数 相对密度Gs 2.676
最大干密度ρdmax/(g·cm?3) 1.6
水的最优质量分数wopt/% 19.5
w2/% 16
w0.06/% 63
w0.002/% 21
D10/mm 0.001
D30/mm 0.004
D60/mm 0.01
塑限PL/% 26.42
液限LL/% 39.97
塑性指数PI/% 13.55
(ρd =1.4 g/cm3)
饱和渗透系数ks/(m·s?1 3×10?8
进气值AEV/kPa 20
水的饱和体积分数φs/% 0.47(脱湿),0.41(吸湿)
水的残余体积分数φr/% 0.10(脱湿),0.10(吸湿)
α/kPa?1 0.035(脱湿),0.045(吸湿)
n 1.26(脱湿),1.24(吸湿)
m 0.21(脱湿),0.19(吸湿)
Tab.1 Summary of measured properties of test soil
Fig.4 Drying and wetting soil water retention curves of test soil compacted to dry density of 1.4 g/cm3
Fig.5 Comparisons of the mechanical properties of the 3D-printed model root with real woody, FDM-printed ABS plastic roots and other materials (after reference [20])
Fig.6 Diagram of 1-g model root water uptake test system
Fig.7 Schematic diagram of test setup for 1-g model root water uptake tests
试验ID p/kPa b/(mol·kg?1) 溶液循环
R-01 0
R-02 1500 0.01915
R-03 750 0.014 00
R-04 3000 0.02675
R-05 1500 0.01915
Tab.2 Summary of 1-g laboratory model test programs
Fig.8 Variations of measured soil matric suction with time for tests
Fig.9 Measured vertical distributions of soil matric suction before and after water uptake by model root
Fig.10 Measured horizontal distributions of soil matric suction before and after water uptake by model root
Fig.11 Relationship between matric suction and unsaturated hydraulic conductivity for test soil
Fig.12 Schematic diagram of concentration polarization phenomenon in model root
Fig.13 Comparison of maximum suction profiles obtained from model root and live plants
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