【作者】 曾召田；

【导师】 吕海波；

【作者基本信息】 广西大学 ， 岩土工程， 2007， 硕士

【摘要】 本文以广西南宁膨胀土为研究对象，以大气作用下膨胀土的干湿循环效应和微观机制为研究目的，结合现场膨胀土边坡的观测资料，通过室内膨胀土强度试验、变形试验和微观试验，较为全面地揭示了干湿循环条件下膨胀土强度和变形的变化规律并分析了其产生干湿循环效应的微观机制，主要研究成果如下：1．在考虑大气影响深度范围内，结合现场含水量的观测数据，对膨胀土干湿循环幅度进行确定；通过室内常规三轴和直剪试验，研究膨胀土在干湿循环条件下其强度的变化规律，并建立了相应的强度衰减公式；在此基础上探讨了干湿循环条件下膨胀土强度与含水量、循环幅度的关系。2．开展膨胀土的膨胀、收缩试验，研究了膨胀土在干湿循环条件下其胀缩变形的变化规律，并建立了相应关系式；在此基础上探讨了干湿循环条件下膨胀土胀缩指标与含水量的关系。3．利用压汞试验测定了干湿循环过程中的孔径分布曲线，并进行了修正分析；运用修正后的孔径分布曲线推算了膨胀土干湿循环过程的土水特征曲线，并分析其变化规律；在此基础上研究了干湿循环过程中基质吸力的变化规律，并建立了相应关系式；最后从微观结构(基质吸力和裂隙性)方面阐述了膨胀土干湿循环效应的产生机制。4．利用试验成果，进行了考虑干湿循环效应的膨胀土边坡稳定性分析，阐述了膨胀土边坡干湿循环分层理论的必要性和可行性。更多还原

【Abstract】 With the research object of expansive soil in Nanning, Guangxi and the aimof the wetting-drying effect and micro-mechanism of expansive soil under theeffect of atmosphere, combining on the observation date of expansive soil slopeof field engineering, the variable law of the strength and deformation ofexpansive soil under wetting and drying cycle are roundly disclosured and themicro-mechanism is analyzed by strength test, deformation test and microscopicview test in laboratory. The main research findings are as follows:1. According to the depth of atmospheric effect and the observation data ofthe moisture content of field engineering, the amplitude of wetting and dryingcycle is determined. Then the variable law of the strength of expansive soilunder wetting and drying cycle is discussed by conventional triaxial test andstraight scissors test, and the attenuation formula of strength is establishedcorrespondingly. Based it on, the relationship between strength and moisturecontent& circulate amplitude of expansive soil under wetting and drying cycleeffect is discussed subsequently.2. Based on the expansion test and shrinkage test, the variable law of thedeformation of expansive soil under wetting and drying cycle is discussed, and the corresponding formula of deformation is also created. Subsequently, therelationship between deformation index and moisture content of expansive soilunder wetting and drying cycle effect is discussed.3. The mercury intrusion porosimetry (MIP) test is applied to determine thepore size distribution curve of expansive soil during wetting and drying cycle,and the results are corrected. And the soil-water characteristic curves (SWCC)which obtained from the MIP test results that are corrected are computed, andthe change rule is also analyzed. Then the attenuation formula of matrix suctionduring wetting and drying cycle is studied, and the corresponding formula ofdeformation is also created. Finally, the wetting-drying effect mechanism ofexpansive soil is analyzed from the microstructure (matrix suction and crack).4. Based on the test results, the stability analysis of expansive soil slope isstudied. Then the necessity and feasibility of the theory for wetting and dryingcycle lamination of expansive soil slope is expounded.更多还原