多次饱水下水化学作用对库岸土体的微结构效应研究  

Study on microstructure effect of chemical reactions after multiple soaked processes of slope soil

作　　者：单慧媚 彭三曦 梁和成[3] 李义连[3] SHAN Huimei;PENG Sanxi;LIANG Hecheng;LI Yilian(College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China;College of Earth Sciences, Guilin University of Technology, Guilin 541004, China;College of Environment, China University of Geosciences, Wuhan 430074, China)

机构地区：[1]桂林理工大学环境科学与工程学院,广西桂林541004 [2]桂林理工大学地球科学学院,广西桂林541004 [3]中国地质大学环境学院,湖北武汉430074

出　　处：《自然灾害学报》2018年第3期39-46,共8页Journal of Natural Disasters

基　　金：国家自然科学青年基金项目(41502232;407002059);广西自然科学基金项目(2017GXNSFAA198096);广西中青年教师基础能力提升项目(2018KY0253);广西重点实验室研究基金项目(1701K010)~~

摘　　要：三峡库区水位涨落导致库岸土体长期处于饱水再失水的反复过程,水动力环境的改变导致其中产生复杂的水化学作用,进一步影响了库岸边坡的稳定性。采集库区库岸土样进行三次饱水再失水试验,测定三次饱水后溶液中离子浓度,观察饱水前后土体的微观结构。通过构建饱水溶液中离子浓度变化与库岸土体的多元回归方程,定量分析水化学作用对其结构参数的影响;通过微结构参数体现的宏观力学特征,进一步分析水化学作用对其工程力学性质的影响。研究发现:(1)库岸土体的颗粒特征主要受到饱水溶液中K^+、Mg^(2+)、Pb^(2+)、F^-、Ca^(2+)的影响,且K^+、Mg^(2+)、Pb^(2+)、F^-浓度与颗粒粒径呈负相关,与颗粒分维、颗粒分布分维呈正相关关系,而Ca^(2+)浓度则相反;(2)库岸土体中方解石和白云石矿物的溶解作用,溶液中K^+被吸附或与其他离子的置换反应会增强土的抗剪强度、内聚力和渗透性;(3)三次饱水下,库岸土体的力学强度增强。In the Three Gorges Reservoir area,fluctuation of river water level causes that soil on the reservoir slope were repeatedly soaked by river water and then dehydrated. The change of hydrodynamic environment leads to complex hydrochemical effects,which further affects the stability of the reservoir slope. In this study,soil samples were collected form the Three Gorges Reservoir area and used for three times of soil soaked and dehydrated experiments.The ions concentrations of solutions were measured and soil microstructure was observed. By constructing the multivariate regression equation between ions concentrations of solutions and soil microstructure parameters,the influences of water chemistry on soil structure were quantitatively analyzed. According to macroscopic mechanical characteristics reflected by microstructural parameters,the effect of water chemistry on the mechanical properties werefurther analyzed. It was found that：（ 1） The particle characteristics of soil were mainly affected by K＋,Mg2＋,Pb2＋,F- and Ca2＋of solutions. Their concentrations were negatively correlated with particle size,and positively correlated with particle size distribution and fractal dimension,while Ca2＋concentration was on the contrary;（ 2）Dissolution of calcite and dolomite minerals in soil samples and K＋ adsorption or replacement by other ions will increase the shear strength,cohesion and permeability of the soil;（ 3） After three times of soil soaked and dehydrated processes,the mechanical strength of slope soil increased.

关 键 词：多次饱水 水化学作用 颗粒参数 力学强度 

分 类 号：TV11[水利工程—水文学及水资源]