【作者】 张涛；

【导师】 曹丽文；

【作者基本信息】 中国矿业大学 ， 地质工程， 2021， 硕士

【摘要】 污染质在土体渗流过程中不断改变其性质结构,反之,土体性质及其演化也会影响渗流运移的特征,两种作用同时进行,互相影响。为研究生活源污染质在土体中的渗流作用及其与土体性质结构的互馈作用关系,以徐州地区的粉质黏土作为研究对象,选择生活源污染质降解过程中的主要成分CH₃COOH为污染质,建立由互馈第一、第二阶段组成的互馈试验系统,在测试并分析不同轴压、渗压条件下土体性质结构动态演变规律的基础上,以CH₃COOH溶质运移质量和运移速率为参数,研究了互馈两个阶段的运移特征,揭示了CH₃COOH污染质渗流作用下土体性质结构与运移的互馈关系及机理。研究表明:（1）CH₃COOH污染质渗流过程中,粉质黏土干密度、孔隙比、抗剪强度及渗透系数等土工性在污染质渗流作用下变化明显。（2）互馈第一阶段CH₃COOH污染质运移的特征:随着渗流路径长度的增加,CH₃COOH污染质质量浓度与电导率变大,变化速率增大;随着渗流运移时间增长,CH₃COOH污染质质量浓度与电导率变大,变化速率呈减小趋势。（3）互馈第二阶段CH₃COOH污染质运移受互馈第一阶段土体结构改变后的反馈作用明显。污染质含量、电导率与运移时间正相关、与渗流路径长度负相关;污染质含量的变化率与运移时间正相关、与渗流路径长度负相关,电导率变化率随运移时间先增后减,随渗流路径长度的变化规律不明显;孔隙比、渗透性较小的土体,CH₃COOH污染质到达相同位置的时间较晚。（4）与互馈第一阶段相比,互馈第二阶段中,污染土中孔隙比、渗透性减小特征阻碍CH₃COOH污染质运移扩散,其抑制作用随渗流路径长度增大而增大;而孔隙比、渗透性变大的土体特征促进CH₃COOH污染质运移,其效果随渗流路径长度增大而减小。（5）CH₃COOH污染质渗流作用下土体性质结构与运移的关系机理为,CH₃COOH污染质与土体发生化学作用,CH₃COOH污染质通过溶蚀土体矿物成分、削弱土颗粒双电层厚度等作用使土体孔隙更加发育,进而增进污染质的运移,同时,CH₃COOH污染质与土体发生的离子交换吸附、附着与沉聚作用会阻碍污染质在土体内的运移。该论文有图54幅,表13个,参考文献121篇。更多还原

【Abstract】 Contaminated materials constantly change their properties and structures in the process of soil seepage.On the contrary,the properties and evolution of soil will also affect the characteristics of seepage migration.The two effects are carried out simultaneously and affect each other.In order to study the seepage effect of domestic pollution in soil and its mutual feedback relationship with soil property structure,silty clay in Xuzhou area was taken as the research object,and CH₃COOH,the main component in the degradation process of domestic pollution,was selected as the pollution.The mutual feedback test system composed of the first and second stages of mutual feedback was established.On the basis of testing and analyzing the dynamic evolution law of soil property structure under different axial compression and seepage pressure,the migration characteristics of the two stages of mutual feedback were studied with the migration quality and migration rate of CH₃COOH solute as the parameters,and the mutual feedback relationship and mechanism of soil property structure and migration under the seepage effect of CH₃COOH pollution were revealed.The study shows that:（1）In the process of CH₃COOH pollutant seepage,the dry density,void ratio,shear strength and permeability coefficient of silty clay change significantly under the action of pollutant seepage.（2）The characteristics of CH₃COOH contaminant transport in the first stage of mutual feedback:With the increase of seepage path length,the mass concentration and conductivity of CH₃COOH contaminant increase,and the change rate increases;With the increase of seepage migration time,the mass concentration and conductivity of CH₃COOH pollutants increased,and the change rate showed a decreasing trend.（3）CH₃COOH transport in the second stage of mutual feedback is obviously affected by the change of soil structure in the first stage of mutual feedback.Pollutant content and conductivity were positively correlated with migration time and negatively correlated with seepage path length;The change rate of pollutant content is positively correlated with the migration time and negatively correlated with the seepage path length.The change rate of conductivity increases first and then decreases with the migration time,and the change law is not obvious with the seepage path length.In soils with lower porosity and permeability,the time of CH₃COOH contamination reaching the same position is later.（4）Compared with the first stage of mutual feedback,in the second stage of mutual feedback,the decrease of void ratio and permeability in contaminated soil hinders the migration and diffusion of CH₃COOH pollutants,and its inhibitory effect increases with the increase of seepage path length;The soil characteristics with larger void ratio and permeability promote the migration of CH₃COOH pollutants,and the effect decreases with the increase of seepage path length.（5）The mechanism of soil property structure and migration under the seepage of CH₃COOH pollutants is that CH₃COOH pollutants react with soil chemically.CH₃COOH pollutants make soil pores more developed by dissolving the mineral composition of soil and weakening the thickness of soil particle double layer,thereby enhancing the migration of pollutants.At the same time,the ion exchange adsorption,adhesion and sedimentation between CH₃COOH pollutants and soil will hinder the migration of pollutants in soil.This paper has 54 figures,13 tables and 121 references.更多还原