摘要
【目的】研究膨润土掺量对砂土渗透性的影响,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%和15%的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10cm/s降低至10cm/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正相关,拟合度R^(2)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R^(2)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。
【Background and objective】Soil permeability is an important engineering parameter modulated by its microscopic structure.The southern section of Yongding River has been drying out of water for a long time with the riverbed deserted.To improve hydro-ecological properties of the riverbed,this paper studied the feasibility of amending the riverbed soil with bentonite.【Method】Sandy soil samples taken from the riverbed were amended with bentonite at ratios ranging from 3%to 15%.Following an incubation,each sample was scanned using the scanning electron microscope(SEM).Penetration test was conducted in a laboratory to measure the permeability,from which we analyzed the relationship between soil permeability and soil microstructure.【Result】Amending the soil with bentonite at ratio of 6%to 15%reduced the soil permeability from 10^(-5)cm/s to 10^(-7)cm/s.Microstructure analysis of the samples amended with bentonite at different ratios showed that with the increase in bentonite content,the microstructure changed gradually from granular structure to agglomerate structure,resulting in a decrease in permeability.The aerial percentage of macropores was positively correlated with permeability.Increasing bentonite content improved the orientation of the pore area distribution,with the percentage of pore area within 80o to 100o decreasing and the ratio of pore area around 20o to 40o and 150o increasing.These combined to reduce the soil permeability.Two-and three-dimensional analysis of the microscopic structure revealed that the pore ratio and the logarithm of the permeability were linearly correlated,with R^(2)being 0.98 for 2D and 0.96 for 3D,respectively.【Conclusion】Adding bentonite to the sandy soils taken from the riverbed of Yongding river showed that the addition improved the pore area,changing the average pore diameter as a result.These combined to reduce soil permeability significantly.
作者
薛万来
李法虎
刘晔
李彬瑜
黄炳彬
XUE Wanlai;LI Fahu;LIU Ye;LI Binyu;HUANG Bingbin(Beijing Water Science and Technology Institute,Beijing 100048,China;College of Water Resources&Civil Engineering,China Agricultural University,Beijing 100083,China;Hebei University of Engineering,Handan 056000,China;Powerchina Beijing Engineering Corporation Limited,Beijing 100024,China)
出处
《灌溉排水学报》
CAS
CSCD
北大核心
2022年第9期85-92,共8页
Journal of Irrigation and Drainage
基金
国家科技重大专项(2018ZX07101005-03)。
关键词
孔隙特征
砂土
渗透性
微观结构
电镜扫描
pore characteristics
sandy soil
penetration
microstructure
SEM
作者简介
薛万来(1989-),男,江苏淮安人。高级工程师,博士,主要从事水土环境工程研究。E-mail:xuewanlai@126.com;通信作者:李法虎(1963-),男,河南新乡人。教授,博士,主要从事水土工程研究。E-mail:lifahu@cau.edu.cn。
