饱和黏土压缩变对离子污染物运移特性影响研究

论文总字数：37218字

摘 要

随着全球经济的发展，土壤遭受重金属污染的事件频频发生，不仅造成生态系统严重破坏，同时还逐渐改变土体的结构与工程性质。

离子污染物在土体中的运移机制主要包括对流、扩散、吸附、弥散、降解以及化学反应等。实际工程中，土体产生固结变形主要是由于自重及上部荷载造成。一方面，污染土的固结变形将引起其中污染物溶液的对流；另一方面，固结变形的发展，会使土的孔隙比、渗透系数和固结系数亦随之改变，污染物在土体中的水动力弥散系数也将发生改变，从而影响离子污染物在土体中的运移特性。

本文通过一维压缩试验，得到压缩变形过程后不同孔隙比下的试样，然后对相应的试样进行内扩散试验，获取不同孔隙比下离子扩散过程引起的水溶液浓度和电导率变化规律的差异性。总结全文，得出的主要研究成果如下:

（1）内扩散试验过程中，由于烧杯水溶液和试样孔隙液浓度梯度的存在，使得离子向土体当中运移。当烧杯内水溶液和试样孔隙液离子浓度相等时，扩散作用将达到平衡状态。内外溶液浓度梯度越大，扩散速度也将越快。

（2）KCl溶液在黏土中进行扩散试验时，高岭土和膨润土孔隙比的改变均会改变溶质在黏土土中的运移特性。烧杯中水溶液K 浓度随着时间推移逐步降低，水溶液电导率随着时间推移亦逐步降低；另一方面，孔隙比越小的试样，扩散平衡时，烧杯中浓度越高，电导率也越高，即离子向黏土体中扩散的量越少。

（3）Zn(NO₃)₂溶液在黏土中进行扩散试验时，高岭土和膨润土孔隙比的改变均会改变溶质在黏土中的运移特性。在扩散试验中，烧杯中水溶液Zn² 浓度随着时间推移逐步降低，水溶液电导率则先增加而后才有一定的减小。

（4）KCl溶液在高岭土和膨润土试样中进行内扩散试验，溶液电导率与钾离子浓度有较好的线性关系，电导率值可以用来辅助对K 浓度变化趋势的解释。

（5）Zn(NO₃)₂溶液在高岭土和膨润土试样中进行内扩散试验，溶液电导率与锌离子浓度在电导率的整个范围内，水溶液电导率值和锌离子浓度没有很好的线性关系。

关键词：高岭土，膨润土，固结试验，离子污染物，内扩散试验。

Abstract

With the development of the global economy, the occurrence of heavy metal pollution in the soil frequently occurred, not only caused serious damage to the ecological system, but also gradually changed the structure and engineering properties of soil.

The transport mechanism of ionic contaminants in soil mainly includes convection, diffusion, adsorption, dispersion, degradation and chemical reaction. In practical engineering, the consolidation deformation of soil is mainly caused by the dead weight and the upper load. On the one hand, the pollution of soil consolidation deformation will cause which contaminant solution of convection; on the other hand, consolidation deformation of the development, the soil pore ratio, permeability coefficient and the coefficient of consolidation are changed, the pollutants in the soil hydrodynamic dispersion coefficient will also change, thus affecting the transport characteristics of pollutant in the soil.

The through one-dimensional compression test, compression deformation process with different porosity than that of the sample and the corresponding specimens is carried out within the diffusion test, to obtain different pore ratio of ion diffusion caused by water solution concentration and the change rules of conductivity differences. Summary of the full text, the main research results are as follows:

(1) Diffusion in the process of test, because of the existence of the beaker of water solution and sample pore fluid concentration gradient, the ion migration to the soil. When the water in the beaker and sample solution ion concentration of pore water is equal, diffusion will reach the equilibrium state. The greater the concentration gradient of inside and outside, the faster the diffusion rate will be.

(2) the change of pore ratio of kaolin and bentonite will change the migration characteristics of the solute in clay soil. KCl solution in the clay of diffusion test and beaker of water solution of K concentration with the passage of time gradually reduce, the electrical conductivity of water solution with the passage of time gradually reduced; on the other hand, pore than smaller specimens, diffusion balance, beaker, the higher the concentration, the higher conductivity that ion to clay soil diffusion amount of less and less.

(3) Zn(NO₃)₂ solution in the diffusion test of clay, kaolin and bentonite pore ratio changes will change the solute transport characteristics in clay. In the diffusion test, beaker of water in the solution concentration of Zn² with the passage of time gradually reduced, the electrical conductivity of water solution increased at first, and then reduced.

(4) KCl solution in the kaolin and bentonite samples in the diffusion test, the solution conductivity and potassium ion concentration has a good linear relationship, the conductivity value can be used to assist in the interpretation of the trend of K concentration change.

(5) Zn(NO₃)₂ solution in the kaolin and bentonite samples were within the diffusion test, conductivity of solution and zinc ion concentration within the entire range of conductivity and the electrical conductivity of water solution value and the concentration of Zn² no good linear relationship.

KEY WORDS: Kaolin, bentonite, consolidation test, ionic contamination, internal diffusion test.

目录

摘 要 I

第一章 绪论 1

1.1 研究背景和研究意义 1

1.2 研究现状分析 2

1.2.1理论研究进展 2

1.2.2 试验研究进展 3

1.3 工程应用 6

1.4本文主要研究内容 7

1.5 研究技术路线与结构框架图 7

第二章 饱和压缩黏土的离子污染物内扩散试验方案 8

2.1 概述 8

2.2 试验材料 8

2.2.1 高岭土和膨润土 8

2.2.2 氯化钾 9

2.2.3 硝酸锌 9

2.3 试验内容及方法 10

2.3.1 一维压缩试验 10

2.3.2 离子运移试验 11

第三章 内扩散试验数据分析 14

3.1 概述 14

3.2 黏土一维固结试验数据 14

3.3 KCl溶液早高岭土试样中的内扩散试验 15

3.3.1 浓度数据 15

3.3.2 电导率值数据 16

3.3.3 电导率值与钾离子浓度关系 17

3.4 Zn(NO₃)₂溶液在高岭土试样中的内扩散试验 18

3.4.1 浓度数据 18

3.4.2 电导率值数据 20

3.4.3 电导率值与锌离子浓度关系 21

3.5 KCl溶液在膨润土试样中的内扩散试验 22

3.5.1 浓度数据 22

3.5.2 电导率值数据 23

3.5.1 电导率值与钾离子浓度关系 24

3.6 Zn(NO₃)₂溶液在膨润土试样中的内扩散试验 25

3.6.1 浓度数据 25

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