吉林省镇赉地区分散性土冲刷机理研究

发布时间：2018-11-17 08:49

【摘要】：近年来随着社会的快速发展,土地越来越多的被需求,尤其是基础设施、公用和民用建筑等都需要一定的空间,因此特殊土的特性研究、改良和利用就显得尤为重要。近年来在岩土工程界分散性土是备受关注的特殊土之一,其抗水侵蚀能力比较差,对水利工程和道路工程等建筑设施的安全稳定性存在威胁。本文结合国家自然科学基金项目“寒旱区土体盐渍化HTSM多场耦合地质环境系统灾变演化机理与工程效应研究”,以吉林省镇赉地区分散性土为研究对象,对不同埋深的土样进行了分散性鉴别试验,并相应的针对土样的基本物理化学性质进行了测试试验,来研究土样在垂直剖面上的基本物理化学性质和分散性的关系,根据实验室情况本文进行了分散性土的三种鉴别试验,即针孔试验、双比重计试验和碎块试验。考虑到分散性土特性,其遇水后很容易崩解,并且很容易被流水带走,遇水后抗剪强度、抗冲蚀能力以及其他物理化学性质都有所改变,因而采用实验室小型边坡模具和降雨装置,对吉林镇赉研究地区分散性土进行室内物理模拟冲刷试验,对分散性土边坡坡面冲刷破坏规律及其主要影响因子(分散性土的含盐量、初始含水率和压实度以及边坡坡度)进行了研究,并获得如下结论:(1)吉林镇赉研究地区经分散性综合判定结果是埋深为10~40cm的土样和埋深为60cm的土样为分散性土,埋深为80cm的土样为非分散性土;土样易溶盐含量较高,大体上易溶盐含量随着埋深的增加而减小,在垂直剖面上土样的分散性与其易溶盐含量变化趋势相似。(2)分散性土边坡坡面室内模拟冲刷侵蚀破坏的整个演变过程分为三个阶段:雨滴溅蚀阶段、遇水分散及冲沟侵蚀阶段。第1阶段冲刷方式主要为雨滴击打作用,雨滴击打在坡面表层土体上,坡面上细小颗粒被雨滴溅蚀,发生分散、破裂及四处飞溅;第2阶段坡面表层的细小颗粒遇水后开始分解成原级粘土颗粒,土体中易溶盐逐渐溶于水中,土体的基本物理化学性质发生变化,各项强度参数受到影响,部分土颗粒失去其稳定性,侵蚀坑开始形成;第3阶段随着降雨的进行,坡面径流明显增大,浅小冲沟形成,并且不断加宽加深严重破坏坡面形状,最终导致坡面完全破坏。(3)根据室内模拟分散性土冲刷试验,深入探讨了初始含水率、含盐量、压实度和边坡坡度等各个因素对分散性土冲刷的影响,研究了分散性土的冲刷机理及分散特性,为吉林省分散性土的坡面冲刷和水利工程的设计防护提供重要的理论指导意义。(4)其他因素也会对土体的分散性有影响,土体中有机质是土颗粒团聚的胶结剂,有机质含量越高,土颗粒团聚性越强,土样的分散性越弱;粘粒具有颗粒细、表面积大的特点,粘粒间存在粘结力,粘粒的含量直接影响土体的通透能力,进而影响分散性土易被冲蚀破坏。
[Abstract]:In recent years, with the rapid development of society, more and more land is needed, especially the infrastructure, public and civil buildings, and so on, so it is very important to study, improve and utilize the characteristics of special soil. In recent years, dispersive soil is one of the most concerned special soils in geotechnical engineering. Its water erosion resistance is poor, which threatens the safety and stability of construction facilities such as water conservancy engineering and road engineering. Based on the project of National Natural Science Foundation of China, "study on the mechanism of catastrophic evolution and engineering effect of multi-field coupling geological environment system of soil salinization in cold and arid region", this paper takes the dispersed soil in Zhenlai area, Jilin Province, as the research object. The dispersion identification tests were carried out on soil samples with different buried depths, and the basic physical and chemical properties of soil samples were tested accordingly to study the relationship between the basic physicochemical properties and dispersibility of soil samples in vertical profiles. According to the laboratory conditions, three kinds of discriminant tests of disperse soil were carried out in this paper, namely, pinhole test, double hydrometer test and fragment test. Considering the properties of dispersed soils, they are easily disintegrated and easily taken away by running water, and the shear strength, erosion resistance and other physical and chemical properties change after water contact, Therefore, laboratory small-scale slope mould and rainfall device were used to carry out indoor physical simulation scour test of dispersed soil in Zhenlai area, Jilin Province. The erosion failure law and its main influencing factors (salt content, initial moisture content and compaction degree and slope gradient of dispersive soil slope) are studied. The following conclusions are obtained: (1) the results of comprehensive determination of dispersion in Zhenlai, Jilin Province are as follows: (1) the samples with 10~40cm buried depth and those with 60cm depth are dispersive soils, and those with 80cm depth are non-dispersible soils; The content of soluble salt in soil sample is high, and the content of soluble salt decreases with the increase of buried depth. The dispersion of soil samples on vertical profile is similar to that of soluble salt content. (2) the whole evolution process of simulated erosion and destruction on slope surface of dispersive soil slope is divided into three stages: raindrop splash erosion stage. Water dispersion and gully erosion stage. In the first stage, the main way of scouring is the impact of raindrops. The small particles on the surface of the slope are splashed by raindrops, which are dispersed, broken and spattered everywhere. In the second stage, the fine particles on the surface of the slope begin to decompose into the original clay particles, and the soluble salt in the soil gradually dissolves in the water, and the basic physical and chemical properties of the soil are changed, and the strength parameters are affected. Some soil particles lose their stability and erosion pits begin to form. In the third stage, the runoff increases obviously, the shallow gullies form, and the slope shape is continuously widened and deepened, which leads to the complete destruction of the slope surface. (3) according to the laboratory simulation of dispersed soil erosion test, The effects of initial moisture content, salt content, compaction degree and slope on the erosion of dispersive soil are discussed, and the erosion mechanism and dispersion characteristics of dispersive soil are studied. It provides important theoretical guidance for slope erosion of dispersed soil in Jilin Province and design and protection of hydraulic engineering. (4) other factors will also affect the dispersion of soil, and organic matter in soil is a cementing agent for soil particle agglomeration. The higher the content of organic matter, the stronger the agglomeration of soil particles and the weaker the dispersity of soil samples. The clay particles have the characteristics of fine particles and large surface area. There is adhesion between the clay particles. The content of clay particles directly affects the permeability of soil, and then affects the erosion and destruction of dispersible soil.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU411

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