盐冻环境下水工混凝土材料耐久性衰减规律研究

发布时间：2018-06-04 16:38

本文选题：水工混凝土 + 盐冻　；参考：《华北水利水电大学》2017年硕士论文

【摘要】：水工混凝土材料遭受冻融循环作用和盐离子的侵蚀破坏已经成为我国西北灌区水工混凝土材料耐久性能衰减的主要因素,严重影响这些区域水利工程安全和效益的发挥。针对西北寒旱灌区水工建筑物承受盐离子侵蚀和冻融循环破坏导致混凝土耐久性衰减等问题,依托河南省科技创新杰出人才计划“基于侵蚀冻融复合作用的水工混凝土结构耐久性衰减规律研究”和华北水利水电大学研究生创新教育计划(YK2015-01)项目,通过对西北典型灌区——景电灌区水工混凝土材料遭受的侵蚀环境进行调查,分析遭受侵蚀破坏混凝土建筑物附近的水样、土样和混凝土残渣,进行化学和XRD衍射分析,明确混凝土材料的主要侵蚀介质。设计混凝土快速冻融室内加速试验,以质量损失和动弹性模量的变化作为耐久性指标,探究不同水胶比、不同粉煤灰掺量、不同引气剂掺量的混凝土,在清水、3.5%NaCl溶液、5%2 4Na SO溶液、3.5%NaCl+5%2 4Na SO复合溶液侵蚀作用下水工混凝土材料的耐久性衰减损伤过程与机理。同时结合室内加速试验所测得的材料参数,建立景电灌区出水塔结构的ANSYS有限元模型进行数值模拟分析,探究盐冻作用前后出水塔结构在自重、风压力、人群荷载和地震荷载等不同工况作用下的静态和动态分析。得出如下结论:(1)掺加适量引气剂的低水胶比混凝土具有良好的抗盐冻耐久性能,掺加粉煤灰混凝土在抗冻要求地区需采取一定的抗冻措施。(2)在冻融循环作用下不同侵蚀溶液对混凝土的抗盐冻耐久性能具有不同的影响,各种侵蚀介质对混凝土质量的影响程度由强到弱依次为3.5%NaCl+5%2 4Na SO3.5%NaCl5%2 4Na SO清水;对混凝土的动弹性模量影响由强到弱依次为:3.5%NaCl+5%2 4Na SO5%2 4Na SO3.5%NaCl清水。(3)通过对出水塔结构进行ANSYS有限元模拟分析,出水塔结构的顶部和混凝土柱体与基础接触的部位是最容易受损伤破坏的部位,在盐冻侵蚀作用下动力荷载对出水塔结构影响大于静荷载对出水塔结构的影响。通过结合我国西北景电灌区对混凝土抗盐冻性能影响的研究,可以为类似工程提供一定的参考价值,对预防和治理西北寒旱灌区混凝土结构受侵蚀退化问题,延长混凝土结构使用寿命,推动我国西北干旱灌区经济的可持续发展,维护西北地区生态环境安全具有重要的意义。
[Abstract]:The freezing and thawing cycles of hydraulic concrete materials and the erosion and destruction of salt ions have become the main factors of durability attenuation of hydraulic concrete materials in northwest irrigation area of China, which seriously affect the safety and benefit of water conservancy projects in these areas. In view of the problems of concrete durability attenuation caused by salt ion erosion and freeze-thaw cycle damage in hydraulic structures in the cold and dry irrigation area of northwest China, Relying on the outstanding talents program of scientific and technological innovation in Henan Province, "study on durability attenuation law of hydraulic concrete structure based on the composite effect of erosion, freeze-thaw" and YK2015-01, the postgraduate innovative education plan of North China University of Water Conservancy and Hydropower, By investigating the erosion environment of hydraulic concrete materials in typical irrigation area of Northwest China, the paper analyzes the water samples, soil samples and concrete residues near the damaged concrete buildings, and carries out chemical and XRD diffraction analysis. Define the main erosive medium of concrete material. The indoor accelerated test of rapid freeze-thaw of concrete was designed. The change of mass loss and dynamic elastic modulus was taken as the durability index to explore the concrete with different water binder ratio, different fly ash content and different air entraining agent content. The damage process and mechanism of durability attenuation of hydraulic concrete under the erosion of NaCl 3.5and 2 4Na so solution are studied in the presence of 3. 5% NaCl solution and 3. 5% NaCl solution and 5. 5% NaCl solution respectively. At the same time, the ANSYS finite element model of water tower structure in Jingdian Irrigation area is established and analyzed by using the material parameters measured by indoor accelerated test, and the self-weight and wind pressure of water tower structure before and after salt freezing are explored. Static and dynamic analysis of crowd load and seismic load under different working conditions. The conclusion is as follows: (1) the low water binder ratio concrete mixed with proper amount of air entraining agent has good durability against salt freezing. The concrete with fly ash should take some anti-freezing measures in the area of freezing resistance. (2) under the action of freeze-thaw cycle, different erosive solutions have different effects on the durability of concrete against salt freezing. The degree of influence of various erosive media on the quality of concrete is 3.5%NaCl 52 4Na SO3.5%NaCl5%2 4Na so water. The influence of dynamic modulus of elasticity of concrete from strong to weak is: 3.5NaCl and 2 4Na SO5%2 4Na SO3.5%NaCl clear water. Through the ANSYS finite element analysis of the water tower structure, the dynamic elastic modulus of concrete is analyzed by ANSYS finite element method. The top of the water tower structure and the contact part between concrete column and foundation are the most vulnerable parts. The dynamic load has more influence on the water tower structure than static load on the water tower structure under the action of salt frozen erosion. Based on the study of the effect of Jingdian irrigation area on the salt and freezing resistance of concrete in Northwest China, it can provide some reference value for similar projects, and it can prevent and control the erosion and degradation of concrete structure in the cold and dry irrigation area of Northwest China. It is of great significance to prolong the service life of concrete structure, to promote the sustainable development of the economy of arid irrigation area in northwest China, and to maintain the ecological environment safety in Northwest China.
【学位授予单位】：华北水利水电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV431

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