基于工业副产品木质素的粉土固化改良技术与工程应用研究

发布时间：2018-03-07 16:15

本文选题：木质素　切入点：粉土　出处：《东南大学》2015年博士论文　论文类型：学位论文

【摘要】：粉土路基处理是我国东南沿海地区交通工程建设经常面临的技术难题,探索经济、高效的粉土改良技术是目前我国岩土工程界迫切需要解决的难题之一。木质素是生物能源和造纸厂生产的主要副产品,目前没有得到有效的利用。本文提出基于工业副产品木质素的粉土改良新技术,深入开展木质素改良粉土的机理和工程特性等研究,旨在为该新技术的推广应用提供科学依据。本文以江苏省交通科学研究计划项目(2013Y04)为依托,以木质素改良路基粉土为研究对象,以揭示其改良机理和工程特性为目标,采用室内试验、理论分析和现场试验相结合的方法,对木质素改良路基粉土技术进行系统研究,主要研究内容和成果如下：(1)系统总结了工业副产品木质素的基本性质和资源化利用现状,对木质素在土体改良中的应用、改良土强度特性、改良机理和本构模型等方面的研究成果进行了分析,指出其存在和需要解决的问题。(2)系统研究了木质素改良后粉土物理力学特性和耐久性的变化规律。通过室内试验,研究了掺量和养护龄期对改良土物理力学特性指标的影响,对比分析了木质素和石灰改良粉土的效果,指出了木质素改良粉土技术的可行性和优势。研究结果表明,木质素可有效提高粉土力学性能,强度随掺量增加而增长,掺量超过一定值后,强度呈降低趋势；对于江苏粉土,木质素最优掺量为12%；木质素改良土的耐久性优于石灰土,抑制收缩能力低于石灰。(3)基于弯曲元测试技术,分析了木质素、水泥改良土小应变剪切模量G0随养护龄期的发展规律,引入归一化参数分析小应变剪切模量和无侧限抗压强度的相关关系,建立了木质素改良土强度的无损评价方法。研究结果表明,两种类型改良土在不同掺量下随龄期变化的小应变剪切模量经归一化参数G28处理后,均表现出相同的变化规律；归一化小应变剪切模量和无侧限抗压强度存在一一对应的关系,小应变剪切模量可作为改良土强度发展的评价指标。(4)通过非稳态热探针测试技术,测试了天然土和木质素改良粉土的热阻系数,研究了含水率、干密度、颗粒粒径和饱和度等因素对热阻系数的影响,建立了预测天然土热阻系数的模型,讨论了木质素掺量和压实含水率对改良土热阻系数的影响,分析了改良土热阻系数随养护龄期的变化规律,探讨了木质素改良土热阻系数与力学指标问的内在联系。研究结果表明,热阻系数随含水率、干密度、颗粒粒径和饱和度增加呈减小趋势,低于“临界含水率”时,热阻系数对含水率变化的敏感性较高：热阻系数与众多影响因素间不呈单一相关关系；改良土热阻系数随木质素掺量和养护龄期增加而增加,60d龄期后,不同掺量试样的热阻系数基本相同。28d龄期后,压实含水率对热阻系数基本无影响；木质素改良土热阻系数与重度呈线性反比关系,与抗压强度和回弹模量总体呈增加趋势。(5)通过电镜扫描(SEM)、压汞分析(MIP)、pH值、电阻率、X射线衍射(XRD)、能谱分析(EDS)和傅里叶变换红外光谱分析(FTIR)等方法,研究了木质素改良后土体微观结构和化学成分的变化特征,揭示了木质素改良土体的机理。研究结果表明,木质素改良土形成致密、稳定的微观结构,未产生新的官能团和矿物成分；土体中主要矿物成分平均晶粒尺寸均有不同程度的减小；木质素主要通过水解反应、质子化反应和静电引力作用,减小双电层厚度并产生具有胶结性质的高分子聚合物,包裹、连接颗粒,填充孔隙。(6)基于能量守恒原理对木质素改良土直接剪切过程各阶段的功能转换关系进行分析,提出了评价木质素改良粉土剪切强度的理论模型；通过三轴压缩试验,研究了改良土临界状态下的强度变化特征,基于边界面塑性理论建立了考虑胶结作用的木质素改良土本构模型。研究结果表明,木质素产生的胶结物质不仅提高粉土的力学性能,还可增强塑性变形能力；具有胶结特性改良土剪切过程的能量分为：破坏颗粒间胶结的能量、颗粒间滚动运动的能量和颗粒间摩擦运动的能量,其中破坏胶结的能量是土体自身的特性,与竖向应力无关；改良土临界状态剪应力随掺量增加而增大,其临界状态线相对于素土发生平行移动,胶结特性对土体抗剪强度的提高主要通过黏聚力反映；新的屈服方程和胶结破坏速率等参数的引入,可较好描述木质素改良土的应力-应变特征。(7)开展工业副产品木质素改良粉土路基现场试验,论证了木质素改良粉土技术的可行性和优越性,提出了相应的施工工艺,并对应用效果进行了系统的评价。总结了木质素改良路基土的经济效益和环境影响,探讨了改良路基土浸出液的处治方法。研究结果表明,木质素改良路基土的强度在养护初期(7d)增长较石灰土慢,28d龄期养护后,12%木质素路基土的路用性能指标优于8%石灰改良土；含水率增多对土体强度增长产生负面影响；木质素改良土建设材料成本低于石灰土的1/10,其土壤环境质量符合二级质量标准。
[Abstract]:The silt subgrade treatment is a technical problem, traffic engineering construction in the coastal area of Southeast China often face the exploration of economy, improved silt efficient technology is one of the difficult problems in geotechnical engineering field at present in our country needs to solve urgently. Lignin is the main by-product of bio energy and paper factory, currently not being used effectively. This paper puts forward the industrial byproduct of wood technology improved silt - based on in-depth research in wood modified silt soil mechanism and engineering characteristics, in order to provide a scientific basis for the promotion and application of new technology. This paper takes Jiangsu Province Transport Science Research Project (2013Y04) as the basis, using lignin modified silty soil subgrade as the research object, to reveal the mechanism and engineering characteristics as the goal, based on the laboratory test, field test and theoretical analysis method combining the modified lignin powder soil subgrade The system research, the main research contents and results are as follows: (1) summarizes the industrial by-product lignin basic properties and utilization status of wood, application in soil improvement, improve soil strength characteristics, modification mechanism and constitutive model of other aspects of the results are analyzed, pointing out the existence of and the problems need to be solved. (2) studied change law of soil physical and mechanical properties and durability in modified wood. Through indoor experiment, studied the effect of dosage and curing time on mechanical properties of improved soil physical, the ratio of the lignin and lime silt effect. This article pointed out the feasibility and advantage of modified lignin powder soil technology. The results showed that lignin can effectively improve the mechanical properties of silty soil, strength increases with the increase of dosage, mixing amount exceeds a certain value, the strength decreased for the river; Su Fentu, optimal lignin content is 12%; the durability of lignin modified soil was better than that of lime soil, inhibit contraction ability is lower than lime. (3) bender element testing technique based on the analysis of the lignin, cement soil small strain shear modulus G0 variation with the curing period, introducing the normalized parameters analysis no correlation between shear modulus and unconfined compressive strength, a nondestructive evaluation method for lignin modified soil strength. The results show that the two types of soil changes in different dosage with the age of the small strain shear modulus by normalized parameters after G28 treatment showed the same variation is small; strain shear modulus normalized and there is no one-to-one correspondence between compressive strength, small strain shear modulus can be used as evaluation index of soil strength development. (4) through the non steady state thermal probe testing technology, testing the natural Resistance coefficient of soil and lignin modified silty soil, studied the water content, dry density, effect of particle size and saturation and other factors on the resistance coefficient, establishes a prediction model of natural soil resistance coefficient, the lignin content and the compaction effect of water content on soil resistance coefficient are discussed, analyzed the soil resistance coefficient changes with the curing period, discusses the internal relation of lignin modified soil resistance coefficient and the mechanical indexes asked. Research results show that the thermal resistance rate, dry density with water, particle size and the increase of saturation decreases below the critical moisture content "," high sensitivity resistance coefficient on the moisture content change: no single correlation between resistance coefficient and numerous influencing factors are; improved soil resistance coefficient with the lignin content and curing age increased after 60d age and the resistance coefficient of different dosage of sample .28d is basically the same age, compaction water ratio has no effect on the resistance coefficient; lignin modified soil resistance coefficient and severe linear inverse relationship was increased and the compressive strength and modulus of resilience in general. (5) by scanning electron microscopy (SEM), mercury intrusion analysis (MIP), pH, electrical resistivity, X X-ray diffraction (XRD), energy spectrum analysis (EDS analysis) and Fu Liye transform infrared spectroscopy (FTIR) method, study the variation characteristics of wood soil microstructure and chemical composition of the modified lignin modified soil, the mechanism was revealed. The results show that lignin modified soil to form a dense, stable microstructure the mineral composition of functional groups and no new generation; the main mineral composition in the soil decreased the average grain size in different degree; lignin mainly through hydrolysis reaction, protonation and electrostatic attraction, reduce the thickness of electric double layer and produce The polymer cement properties of inclusions, connecting particles, pore filling. (6) the energy conservation principle of lignin modified soil direct shear process of each phase function conversion relationship based on the analysis, puts forward the theoretical evaluation model of lignin modified silty soil shear strength; the three axial compression test, the intensity of the changing characteristics of improvement the critical state soil, considering the cementation of lignin modified soil constitutive model is established based on the theory of boundary surface plasticity. The results show that the cementing material of lignin which not only improve the mechanical properties of the silt, can also enhance the ability of plastic deformation; cementation has improved soil shearing process energy is divided into: destroy the intergrain bond energy, energy and particle between the rolling motion of the friction between the moving energy, including the destruction of cemented energy is a property of soil, and the vertical stress ; soil critical shear stress increases with the dosage increased, the critical state line relative to the soil occurred parallel move, improve the cement properties on soil shear strength mainly through cohesion into reflection; the yield equation and bond failure rate of the new parameter, can better describe the lignin modified soil the stress strain characteristics. (7) the development of the industrial by-product Lignin Modified Silt Subgrade field test demonstrates the feasibility and superiority of lignin modified soil powder technology, the corresponding construction process was proposed and the effect of the application of the evaluation system. The economic and environmental effects of modified lignin are summarized the subgrade soil, discusses the treatment methods for improvement of subgrade soil leaching solution. The results showed that lignin modified soil subgrade strength in the maintenance period of lime (7D) growth is relatively slow, the age of 28d maintenance, 12% lignin of subgrade soil The road performance index is better than 8% lime improved soil. The increase of moisture content has a negative effect on soil strength growth. The material cost of lignin modified soil construction is lower than that of lime soil 1/10, and its soil environmental quality conforms to the two level quality standard.

【学位授予单位】：东南大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U416.16

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