| Cite this article: | 薛万来.,李法虎,李彬瑜,等.膨润土添加对土壤渗透性及微观结构影响研究[J].灌溉排水学报,0,():-. |
| Xue Wanlai,LI Fahu,LI Binyu,et al.膨润土添加对土壤渗透性及微观结构影响研究[J].灌溉排水学报,0,():-. |
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| Effects of bentonite addition on soil permeability and microstructure |
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Xue Wanlai1, LI Fahu2,3,3,4, LI Binyu5, LIU Ye6
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1.Beijing Water Science and Technology Institute;2.College of Water Resources &3.amp;4.Civil Engineering,China Agricultural University;5.Beijing Engingeering Corporation Limited;6.Hebei University of Engineering
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| Abstract: |
| 【Background】Permeability is one of the important engineering properties of soil and is largely affected by its structure of microscopic system. Most of the existing studies reveal the change of permeability characteristics with soil pore structure and its reasons by qualitative microscopic pore structure, but few studies are from the perspective of quantitative microstructure, especially from the directional arrangement of pores. The influence of pore structure parameters on the change of soil permeability needs to be further studied. 【Objective】The rivers in the southern section of the Yongding River Plain have been dry for a long time, and the river bed has been severely desertified. In order to improve the characteristics of the river bed matrix, this experiment took the surface sandy soil of the Yongding River as the research object, and studied the effects of adding different proportions of bentonite on sandy soil permeability. The study aim is to provide a theoretical basis for the construction of ecological water surface and a support for the goal of "controlling seepage and constructing ecological water surface" in the Yongding River. 【Method】Based on scanning electron microscope observation and penetration test in laboratory, the relationship between the permeability of the improved sandy soil and its microstructure change was studied. The addition ratio of bentonite was set at 5 different levels of 3%, 6%, 9%, 12%, and 15%. The effects of different bentonite additions on soil permeability and microstructure were systematically measured. 【Result】The experimental results showed that the permeability coefficient of the improved sandy soil decreased from 10-5 cm/s to 10-7 cm/s when the content of bentonite was increased from 6% to 15%, which indicates that the content of bentonite had a significant effect on the permeability of the improved sand. The micromechanism analysis of the samples with different bentonite contents showed that with the increase of bentonite content, soil sample structure was gradually changed from granular structure to aggregates, which resulted in the decrease of soil permeability coefficient. The area percentage of macropores was positively correlated with the permeability coefficient of the improved sand. With the increase of bentonite content, the orientation of internal pore area distribution was improved. The percentage of pore area within 80° to 100° was decreased, and the ratio of pore area around 20° to 40° and 150° increased, thus reducing the permeability coefficient. Linear regression relationships existed between the pore ratio e and the logarithm of the permeability coefficient, obtained from the two-dimensional and three-dimensional spaces at the microscopic level, and the fitting degrees R2 were 0.98 and 0.96, respectively, which is consistent with the macroscopic laws. 【Conclusion】By adding bentonite, the pore area of the sandy soil can be improved, the average pore diameter of the soil can be changed, and its permeability coefficient can be significantly reduced. |
| Key words: Sandy soil; Penetration; Micro structure; SEM |
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