【作者】 周海龙；

【导师】 申向东；

【作者基本信息】 内蒙古农业大学 ， 农业水工建筑物， 2015， 博士

【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。更多还原

【Abstract】 The research of durability and reinforcement mechanism for cement soil is a key problem to spread and application in northern cold areas. In view of lower strength and poor durability of common cement soil, meanwhile, in order to solve massive industrial waste like fly ash and desulfurization gypsum produced by coal-fired power plant in our region, a new type of composite cement soil material was prepared by adding coal-fired power plant industrial waste like fly ash and desulfurization gypsum. And then, their mechanics properties, durability, damage characteristics and reinforcement mechanism were researched by testing in the laboratory, which provide theoretical basis and test data for them widely used in Inner Mongolia area.Firstly, the strength prediction model for composite cement soil was built, and the best mix proportion for the components material of composite cement soil was proposed.(1)The unconfined compressive strength tests of common cement soil were carried out considering different cement mixing ratios, different curing ages, different specification and molding methods, and its characteristics were basically mastered. The cement soil is prepared of typical silty soil which is distributed in the Tu Mo Chuan branch one of Yellow River irrigation located in Inner Mongolia area.(2)Either fly ash or desulfurization gypsum incorporated into common cement soil, the influence law of strength affected by the mixing amount of fly ash or desulfurization gypsum was researched.(3)Through orthogonal testing and additional testing, the influence law of strength affected by the combining admixture of fly ash and desulfurization gypsum were researched, the best mix proportion for the components material of composite cement soil was proposed and verified, and the strength prediction model was built.Secondly, a completely new nonlinear elastic constitutive model for composite cement soil was built, and its deformation and failure characteristics were analyzed.(1)According to the characteristics of whole stress-strain curve for composite cement soil under uniaxial compression condition, using growth function logistic to fit upward section of the curve and using composite hyperbolic function to fit downward section of the curve, the author was first put forward nonlinear elastic constitutive model for composite cement soil which was better than traditional CSDC-2002 model.(2)According to the characteristics of deviator stress- axial strain curve for composite cement soil under triaxial compression condition, nonlinear elastic model named “three-segment method”by the author, and its complete derivation process or parameter calculation process was given.(3)The relationship between deformation modulus or failure strain with unconfined compressive strength was researched; meanwhile, the failure model of composite cement soil under uniaxial compression or triaxial compression condition was analyzed.Thirdly, the durability of composite cement soil material was evaluated, and comparative analysis with common cement soilˊs durability was made.(1)Drying-wetting and freezing-thawing cycle test showed that resistant to drying-wetting cycle capacity and frost resistance for composite cement soil was better than common cement soil.(2)Three-temperature freezing-thawing cycle test showed that the integral displacement of composite cement soil was shorter than common cement soil; when the soil materialˊwater content in the base is close to optimum water content, congruent composite cement soil sampleˊs integral displacement is the minimum and frost resistance is the best.Fourthly, the analysis method of microstructure for composite cement soil was innovated; also, its reinforcement mechanism and damage characteristics were researched.(1)The making sample method that cement soil sample is observed by atomic force microscope(AFM) was put forward and used in practice; the microstructure of non-conducting composite cement soil sample is also observed by field emission environment scanning electron microscope.(2)Based on microstructure analysis, reinforcement mechanism of composite cement soil was explored; besides, based on uniaxial compression damage test, damage evolution law was analyzed; the elastic-plastic damage model of composite cement soil under uniaxial compression condition was deducted and built.更多还原