脱硫石膏—粉煤灰复合水泥土耐久性能与固化机理研究

发布时间：2018-03-19 03:06

  本文选题：脱硫石膏　切入点：粉煤灰　出处：《内蒙古农业大学》2015年博士论文　论文类型：学位论文

【摘要】：水泥土耐久性和固化机理研究是在北方寒区推广和应用水泥土的关键。鉴于普通水泥土强度低,耐久性差的特点,同时为解决我区燃煤电厂产生的大量工业废料粉煤灰和脱硫石膏,特提出利用它们配制出一种新型的复合水泥土材料。然后开展室内试验,研究这种复合材料的力学特性、耐久性、损伤特性及固化机理,为将该复合材料在内蒙古地区的广泛应用提供理论依据和试验数据。1、建立了复合水泥土的强度预测模型,提出了各组分材料的最优配合比。(1)通过开展不同水泥掺入比、不同龄期及不同试件规格及成型方法下普通水泥土的无侧限抗压强度试验,基本掌握利用内蒙古黄河灌区土默川分灌区典型粉质土配制得水泥土的一些强度特性。(2)在普通水泥土基础上单掺粉煤灰和脱硫石膏,研究其掺量对强度的影响规律。(3)通过正交试验和补充试验,研究复掺粉煤灰和脱硫石膏对其强度的影响规律,得出最优配合比并进行验证,建立强度预测模型。2、建立了一种全新的复合水泥土非线性弹性本构模型,分析了其变形与破坏特征。(1)根据单轴受压下复合水泥土全应力-应变曲线的特点,首次提出用生长函数logistic拟合曲线的上升段,采用复合双曲线函数拟合曲线的下降段,建立分段非线性本构模型,较传统CSDC-2002模型拟合效果更好。(2)根据三轴受压下复合水泥土偏应力-轴向应变曲线的特点,建立“三段法”非线性弹性模型,给出了完整的推导过程和参数计算过程。(3)研究了变形模量、破坏应变与无侧限抗压强度的关系,并分析了单轴受压与三轴受压情况下复合水泥土的破坏形态。3、评价了复合水泥土材料的耐久性,开展了与普通水泥土耐久性的对比分析。(1)干湿和冻融循环试验均表明复合水泥土的耐干湿循环能力和抗冻性能均优于普通水泥土。(2)三温冻融循环试验表明复合水泥土的整体位移小于普通水泥土;当基层土料含水量接近最优含水量时,叠合复合水泥土试样的整体变形量最小,抗冻性能最佳。4、创新了复合水泥土材料的微结构分析方法,研究了其固化机理和损伤特性。(1)提出了原子力显微镜AFM观察水泥土材料样品的制样方法,将其用于微结构的观察;同时也利用场发射环境扫描电镜观察了非导电复合水泥土试样的微结构。(2)在微结构分析的基础上,探讨了复合水泥土的固化机理;在单轴压缩损伤试验的基础上,分析了复合水泥土的损伤演化规律,推导建立了复合水泥土在单轴压缩条件下的弹塑性损伤模型。
[Abstract]:The study of durability and solidification mechanism of cement-soil is the key to popularize and apply cement-soil in the cold region of northern China. In view of the characteristics of low strength and poor durability of ordinary cement-soil, At the same time, in order to solve a large amount of industrial waste fly ash and desulphurization gypsum produced by coal-fired power plant in our region, a new kind of composite cement-soil material is put forward. The durability, damage characteristics and solidification mechanism of the composite are provided with theoretical basis and experimental data for its wide application in Inner Mongolia, and the strength prediction model of composite cement-soil is established. It is put forward that the test of unconfined compressive strength of ordinary cement-soil under different cement mixing ratio, different age, different specimen specification and molding method is carried out by the optimum mix ratio of each component material. Basically master some strength characteristics of cement soil prepared from typical silty soil in Tumechuan irrigation area of Inner Mongolia Yellow River Irrigation area) only add fly ash and desulphurized gypsum on the basis of ordinary cement soil. Through orthogonal and supplementary tests, the influence of fly ash and desulphurized gypsum on its strength is studied, and the optimum mix ratio is obtained and verified. A new nonlinear elastic constitutive model of composite cement-soil is established. The deformation and failure characteristics of composite cement-soil are analyzed according to the characteristics of stress-strain curve of composite cement-soil under uniaxial compression. For the first time, a piecewise nonlinear constitutive model is established by using the growth function logistic to fit the rising segment of the curve and the compound hyperbolic function to fit the descending section of the curve. According to the characteristics of stress-axial strain curve of composite cement-soil under triaxial compression, a "three-stage method" nonlinear elastic model is established, which is better than the traditional CSDC-2002 model. The relationship between deformation modulus, failure strain and unconfined compressive strength is studied. The failure mode of composite cement-soil under uniaxial compression and triaxial compression is analyzed, and the durability of composite cement-soil material is evaluated. A comparative analysis of durability of cement soil and ordinary cement soil was carried out. (1) dry wet and freeze-thaw cycle tests showed that the dry and wet cycle resistance and frost resistance of composite cement soil were superior to those of ordinary cement soil. 2) Three-temperature freeze-thaw cycle test showed that composite water was better than that of common cement soil. The whole displacement of soil is smaller than that of ordinary cement soil. When the moisture content of the base soil is close to the optimal water content, the composite cement-soil sample has the smallest overall deformation and the best frost resistance .4. the microstructural analysis method of the composite cement-soil material is innovated. The curing mechanism and damage characteristics of the cement soil were studied. (1) the method of atomic force microscope (AFM) was proposed to observe the sample of cement soil material, and the method was used to observe the microstructure of cement soil. At the same time, the microstructure of non-conductive composite cement-soil sample was observed by using field emission environment scanning electron microscope (SEM). On the basis of microstructure analysis, the solidification mechanism of composite cement-soil was discussed, and on the basis of uniaxial compression damage test, the solidification mechanism of composite cement-soil was discussed. The damage evolution law of composite cement-soil is analyzed and the elastic-plastic damage model of composite cement-soil under uniaxial compression is derived.
【学位授予单位】：内蒙古农业大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU43;TU472
，

本文编号：1632531