酸侵蚀下红土特性变化及对土石坝坝坡稳定性的影响研究

发布时间：2018-03-13 09:35

本文选题：酸侵蚀　切入点：红土强度　出处：《昆明理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：工业排污和化肥、农药等长期入侵,造成红土中的矿物成分发生了变化,随着污染逐渐加剧,其对红土物理力学特性的影响已经凸显。结合国内外关于污染土的研究现状,主要着眼于云南红土覆盖区域水环境的变化,研究酸性污染对红土矿物成分的影响,分析受蚀红土的劣化过程,讨论污染程度与红土工程指标的关系,进而研究矿物组成、水环境变化对红土抗剪强度的影响,探究酸性库水环境对红土堤坝安全运行的威胁,以期建立相关的量化关系式。研究过程中,使用常规土工试验来获取红土的相关工程指标,应用离子检测来获得土中化学成分的变化数据,并通过两者之间的相关性来建立红土中有效成分与斜坡安全性的关系式。污染物对红土的侵蚀速度是十分缓慢的,为了在研究期限内达到足够的化学反应,依据加速寿命试验原理,采用以浓度换时间的方式来剖析受蚀红土的演化趋势,运用数值模拟结合多元线性回归理论,探讨受蚀红土中有效成分的离子滤出量与工程指标的关系,并将研究成果运用于红土大坝坝坡安全鉴定的工程实例之中。研究结果表明:蒙脱石由于特殊的晶格结构,具有遇水膨胀的特性,其含量对土体的抗剪强度有着重要的影响;水的矿化度对粘性土强度的作用,主要是通过矿物的构成和水中的离子来实现的;若水的矿化度高、土中蒙脱石的含量较大,则对红土抗剪强度的影响较大。黏土矿物中的有效成分发生化学反应,使其胶结物质破坏溶蚀,是导致红土强度降低的根本原因;由于倍半氧化物与酸性物质发生反应,铁、铝离子的析出量随着酸浓度的增大而增多;二氧化硅与氧化钛并未与酸反应,故硅和钛离子的析出量很小。涉水斜坡的渗流安全和稳定性均与土体中有效成分的含量密切相关,据此初步建立了红土中4种主要成分的离子损失量与渗透系数、抗剪强度的量化关系式。相关的传统技术侧重于对土体进行物理力学分析,来判断斜坡的渗流状态和稳定性是否符合规范要求,并对欠缺部位进行充填或力学加固。在研究酸性水环境对红土长期侵蚀的基础上,本文提出了与工程指标密切相关的“有效成分”设想,初步明晰了各有效成分的损失对渗流安全、斜坡稳定性的重要作用。继续深入研究或可将其发展为传统技术的一种补充方法,从而有针对性地添加红土中损失的有效成分,使地质灾害的防范和除险加固得以事半功倍。
[Abstract]:Industrial sewage, chemical fertilizer, pesticide and other long-term invasion have caused changes in the mineral composition of red soil. With the gradual intensification of pollution, its impact on the physical and mechanical properties of laterite has become prominent. This paper focuses on the change of water environment in Yunnan laterite covering area, studies the influence of acid pollution on the mineral composition of laterite, analyzes the deterioration process of eroded laterite, discusses the relationship between pollution degree and engineering index of laterite, and then studies the mineral composition. The influence of the change of water environment on the shear strength of red soil, and the threat of acid reservoir water environment to the safe operation of red earth dike are explored, in order to establish the relevant quantitative relationship. In the course of the research, conventional geotechnical tests are used to obtain the engineering indexes of red soil. The change data of chemical composition in red soil are obtained by ion detection, and the relationship between active components and slope safety of red soil is established by the correlation between them. The erosion rate of pollutants to red soil is very slow. In order to achieve enough chemical reactions within the study period, according to the principle of accelerated life test, the evolution trend of corroded laterite was analyzed by using the method of concentration changing time, and the numerical simulation combined with multivariate linear regression theory was used to analyze the evolution trend of eroded laterite. The relationship between the amount of ion filtration and the engineering index of the active components in the eroded laterite is discussed, and the research results are applied to the engineering example of the safety appraisal of the large dam slope of the laterite. The results show that the montmorillonite is due to the special lattice structure. It has the property of water swelling and its content has an important influence on the shear strength of soil; the effect of water salinity on the strength of cohesive soil is mainly realized by mineral composition and ions in water; if the salinity of water is high, If the content of montmorillonite in clay is large, the shear strength of laterite is greatly affected. The chemical reaction of active components in clay minerals, which causes the destruction and dissolution of cemented material, is the fundamental cause of the decrease of the strength of laterite. The precipitation of iron and aluminum ions increases with the increase of acid concentration, while silica and titanium oxide do not react with acid. Therefore, the amount of precipitation of Si and Ti ions is very small. The safety and stability of seepage on wading slope are closely related to the content of active components in soil. Based on this, the ion loss and permeability coefficient of the four main components in laterite are preliminarily established. Quantitative relationship of shear strength. Traditional techniques focus on physical and mechanical analysis of soil to determine whether the seepage state and stability of slopes meet the requirements of the code. On the basis of studying the long-term erosion of laterite by acidic water environment, this paper puts forward the idea of "effective component" which is closely related to the engineering index. The importance of the loss of each active component to the safety of seepage and the stability of slope is preliminarily clarified. Further research is carried out or can be developed as a supplementary method of traditional technology, so as to add the lost effective component of red soil. Geological hazard prevention and reinforcement can be doubled with half the effort.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P642.132;TV641

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