| 引用本文: | 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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| 摘要: |
| 【目的】本文研究了膨润土掺量对砂土渗透性的影响，旨在为永定河构建生态水面提供理论依据。【方法】通过室内土柱试验，设置了膨润土添加比例分别为3%、6%、9%、12%、15%等5个不同水平，系统探究不同膨润土添加量对土壤渗透性及微观结构的影响。【结果】当膨润土掺量从6%增加到15%时，改良砂土的渗透系数从10-5 cm/s降低至10-7 cm/s，表明膨润土掺量对改良砂土渗透性有显著影响；对不同膨润土掺量的试样进行微观机理分析可知，随着膨润土掺量的增多，土样结构逐渐由颗粒结构体转变为团粒体，从而导致土体的渗透系数减小，且大孔隙的面积百分比与改良砂土渗透系数对数成正相关，拟合度R2为0.89；随着膨润土掺量的增加，内部孔隙面积分布的定向性有较好的改善，从而降低渗透系数；从微观层面二维平面与三维空间所求的孔隙比e与渗透系数对数呈线性回归关系，拟合度R2分别为0.98和0.96，其结果与宏观规律一致。【结论】添加膨润土可改善土体孔隙面积，改变土体平均孔径，显著降低砂土渗透系数。 |
| 关键词: 砂土;渗透性;微观结构;电镜扫描 |
| DOI： |
| 分类号:TU411 |
| 基金项目: |
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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 |
