冻融循环下镇赉地区非饱和盐渍土及石灰固化土的力学特性及机理研究

发布时间：2017-12-31 15:26

  本文关键词：冻融循环下镇赉地区非饱和盐渍土及石灰固化土的力学特性及机理研究　出处：《吉林大学》2017年博士论文　论文类型：学位论文

  更多相关文章： 碳酸盐渍土 力学强度 基质吸力 机理分析 损伤模型

【摘要】：土壤盐渍化对工程建设、人类活动、经济发展等存在一定的威胁。吉林省镇赉县处于吉林省西部地区,该地区分布大量碳酸盐渍土,同时为典型的季冻土区。盐渍土中含有一定量的易溶盐,当含水率较低时,会有部分易溶盐饱和析出,以晶体的形式存在,当含水率逐渐升高时,易溶盐完全溶解于孔隙水中,会造成结构的破坏,降低土体的强度,因此盐渍土受含水率、含盐量等条件的影响极大。镇赉县冬季寒冷,夏季炎热,冻融循环会逐渐改变土体的内部结构而影响土体的强度。因此,有必要对镇赉地区盐渍土进行不同含水率、含盐量、冻融循环次数下的力学强度研究。同时,由于盐渍土易吸收外界的水分而不易消散,大大降低土体的强度,需对盐渍土进行改良。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”(NO.41430642),“松嫩平原分散土成因机制及水热盐耦合离子迁移模型研究”(N0.41372267),以镇赉地区盐渍土为研究对象,首先研究了盐渍土在不同含水率、含盐量及冻融循环次数下的无侧限抗压强度及抗剪强度的变化规律,但考虑到夏季多雨条件下盐渍土强度无法满足工程建设的需要,采用性价比较高的石灰进行改良,研究了石灰固化盐渍土在不同石灰掺量、养护龄期及冻融循环次数下的无侧限抗压强度及抗剪强度的变化规律。同时考虑到盐渍土为非饱和土,利用滤纸法对各影响因素下的盐渍土进行了基质吸力的量测,并分别建立了基质吸力与无侧限抗压强度及抗剪强度的关系式,为从机理上研究盐渍土及石灰固化盐渍土的力学性质提供了一定的依据。然后利用压汞法研究了盐渍土及石灰固化盐渍土的孔隙分布特征,并利用扫描电镜对微观结构进行了定性分析及定量分析,从微观角度解释了盐渍土及石灰固化盐渍土的变化规律。综合力学试验、非饱和基质吸力试验及微观试验,以宏观微观相结合的形式讨论了盐渍土及石灰固化盐渍土的变化机理。最后基于损伤理论,利用Weibull函数建立了盐溃土的损伤本构模型。在此基础上,将冻融循环次数考虑进模型中,建立了镇赉地区考虑冻融循环次数的损伤模型。论文共分8章,第1章为绪论,主要介绍选题依据、研究意义、国内外研究现状、文章的主要内容及技术路线、主要创新点等内容。第2章主要研究了结构性、含水率、含盐量、冻融循环次数对镇赉地区盐渍土无侧限抗压强度的影响及石灰掺量、养护龄期、冻融循环次数对石灰固化盐渍土无侧限抗压强度的影响。第3章主要研究了结构性、含水率、含盐量、冻融循环次数对镇赉地区盐渍土抗剪强度的影响及石灰掺量、养护龄期、冻融循环次数对固化盐渍土抗剪强度的影响。第4章主要研究了基质吸力与各影响因素的关系,同时建立了基质吸力与无侧限抗压强度、抗剪强度的关系式。第5章通过压汞试验及电镜试验研究了盐渍土的微观特性。第6章从机理上分析了盐渍土及石灰固化盐渍土的强度变化。第7章建立了盐渍土的弹塑性损伤模型。第8章为结论及建议,总结了文章的研究成果,并提出了下一步的计划。
[Abstract]:Soil salinization of engineering construction, human activities, economic development has certain threat. Jilin County of Zhenlai province in the western region of Jilin Province, the extensive distribution of saline alkali soil in the area, at the same time as the typical seasonal frozen soil area. The soluble salt containing a certain amount of saline soil, when the moisture content is low, there will be some the soluble salt precipitation, exist in crystal form, when the water content is gradually increased, the soluble salt is completely dissolved in the pore water will cause structural damage, reduce the strength of the soil, so the saline soil moisture content, effect of salinity conditions greatly. The cold, hot summer cold in winter in Zhenlai county. Thaw cycle will gradually change the internal structure of soil and affect the strength of soil. Therefore, it is necessary to saline soil in Zhenlai area of different water content, salt content, freezing and thawing cycles on the mechanical strength of the saline soil. At the same time, because of easy to absorb The water is not easy to dissipate, greatly reduce the strength of the soil, necessary to improve saline soil. Combined with the National Natural Science Foundation Project: "soil salinization in cold and arid regions HTSM multi field coupling effect mechanism and engineering geological environment disaster evolution system research" (NO.41430642), "Research on migration model and formation mechanism of soil water and heat dispersion salt ion coupling in the Songnen Plain" (N0.41372267), the saline soil in Zhenlai area as the research object, firstly study the saline soil under different moisture content, variation of unconfined compressive strength and shear strength of the salt content and freeze-thaw cycles under, but considering the strength of salinized soil conditions can not meet the rainy summer the needs of engineering construction, the ratio of higher lime improved on solidified soil lime in different amount of lime, the unconfined compressive strength of curing time and freeze-thaw cycles under And the shear strength changes. At the same time taking into account the saline soil in unsaturated soil, saline soil by using filter paper method and influencing factors of the measurement of matrix suction, and establishes a suction and no relation of compressive strength and shear strength, provides a certain basis for mechanics study on the properties of solidified saline soil in saline soil and lime in mechanism. Then the pore distribution characteristics of solidified saline soil in saline soil and lime mercury pressure method, and the microstructure was analyzed by scanning electron microscopy and quantitative qualitative analysis, explained the variation of solidified saline soil and lime saline soil from microcosmic angle. Mechanical test, matrix suction of unsaturated test and microstructure test, by combining the macroscopic and microcosmic form discussed the change mechanism of solidified saline soil in saline soil and lime. Finally, based on the damage theory, the use of Weibull The function of the establishment of salinized soil damage constitutive model. On this basis, the number of freeze-thaw cycles into the model, the establishment of the Zhenlai area with freezing thawing cycles injury model. The thesis consists of 8 chapters, the first chapter is the introduction, mainly introduces the background, research significance, research status at home and abroad, mainly the contents of the article and technical route, the main innovation points. The second chapter mainly study the structure, moisture content, salt content, freeze-thaw cycles, unconfined compressive strength and the influence of lime content on saline soil in Zhenlai area, curing period, freeze-thaw cycles the impact of unconfined compressive strength the lime solidified soil. The third chapter mainly study the structure, moisture content, salt content, freeze-thaw cycles and the impact strength of lime dosage on shear of saline soil in Zhenlai area, curing period, effect of freeze-thaw cycles on shear strength of solidified soil. The fourth chapter mainly studies the matrix suction and the influence factors, and establish the matric suction and the unconfined compressive strength, anti shear strength. The relation between the microscopic characteristics of the fifth chapter of saline soil was investigated by mercury injection test and SEM test. The sixth chapter analyzes the change of strength of solidified saline soil in saline soil and lime. From the mechanism. The seventh chapter establishes saline soil elastoplastic damage model. The eighth chapter is the conclusion and suggestion, summarizes the research results of the article, and put forward the next step of the plan.

【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TU44
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本文编号：1360357