水工混凝土在多因素耦合作用下的性能劣化规律研究
发布时间：2018-11-06 11:01
【摘要】：混凝土耐久性研究是材料科学研究领域的一个重要方面,随着混凝土结构的广泛使用,使用环境日益严酷,其受到环境影响的危害性也日益增加,环境条件的严酷程度决定了混凝土结构工程寿命的长短。我国西部建成的灌区集中分布在内陆河流域和黄土高原地区,特殊的气候、地理环境以及地面大水漫灌引起的区域水盐运移、水位变化,造成灌区水工混凝土受到碳化、侵蚀、干湿循环等破坏作用,导致混凝土结构损伤劣化速度明显高于我国其它地区。在实际使用环境下,混凝土结构可能遭受各种各样的复杂环境,需要加强更加贴近实际使用环境的混凝土劣化规律研究,在实际使用环境中有相当多的混凝土结构不仅会受到碳化、侵蚀、干湿循环等破坏作用,还会受到自重本身、设计水位、加大水位、人群、风和地震等环境因素的影响,因此对混凝土多因素作用下的劣化规律研究具有深远意义。本文以水工混凝土材料和U型渡槽结构为典型研究对象,采用现场调查、X光衍射、室内加速试验、理论分析的研究方法开展水工混凝土材料在碳化、侵蚀、干湿循环作用下的性能劣化规律研究,提取室内加速试验得到的部分相关参数,在不同工况组合下,利用ANSYS三维有限元软件对渡槽结构进行应力和变形规律分析。主要内容如下:(1)考虑灌区水工结构的实际施工要求与高性能混凝土配合比的工程应用,设计不同配合比的结构试件,将现场采集的混凝土残渣磨碎,在X衍射仪器中做衍射试验,确定混凝土结构的主要侵蚀离子,选择合理的腐蚀环境和腐蚀制度模拟我国西部当地混凝土结构所处的腐蚀环境,研究混凝土损伤劣化全过程。(2)综合试验数据和理论分析,以试件的质量损失率和相对动弹性模量为评价指标,研究腐蚀方式、水灰比、粉煤灰掺量对混凝土耐久性能衰减的影响,探寻混凝土劣化本质。(3)提取试验所得到的相关数据,在理论上对渡槽钢筋混凝土的弹性模量、容重等材料特性进行等效处理,对耦合破坏作用前后的渡槽结构进行数值分析,研究渡槽排架在耦合破坏作用前后不同荷载组合下渡槽结构的应力和变形规律。研究结果表明:碳化虽然能够密实混凝土表层,但由于化学成分的改变,混凝土材料劣化速度反而加快,粉煤灰掺量为20%时,混凝土抗硫酸盐性能达到相对较优化的状态,低水灰比较高水灰比可有效地阻碍侵蚀离子渗透。渡槽排架在耦合破坏作用后,拉应力、切应力和位移的增加更易使局部混凝土结构产生开裂的现象,特别在耦合破坏部位,增长幅度很大,极易产生裂缝。研究成果为混凝土耐久性能研究提供参考,为渡槽结构设计和运行过程中的使用维护提供理论依据。
[Abstract]:The study of concrete durability is an important aspect in the field of material science. With the extensive use of concrete structures, the environment is becoming increasingly harsh, and the harm caused by environmental impact is increasing day by day. The severity of environmental conditions determines the length of life of concrete structures. The irrigation areas built in the west of China are concentrated in the inland river basins and the Loess Plateau. The special climate, geographical environment and regional water and salt migration caused by flood irrigation on the ground, the change of water level, cause carbonization and erosion of hydraulic concrete in irrigation areas. The damage rate of concrete structure is obviously higher than that in other parts of China. In the actual use environment, concrete structure may suffer from various complex environments, so it is necessary to strengthen the study of concrete deterioration law which is closer to the actual use environment. In the actual environment, many concrete structures will not only be destroyed by carbonation, erosion, dry-wet cycle, but also affected by environmental factors such as weight itself, design water level, increasing water level, crowd, wind and earthquake, etc. Therefore, it is of great significance to study the deterioration law of concrete under the action of many factors. In this paper, hydraulic concrete materials and U-shaped aqueduct structures are taken as typical research objects. The methods of field investigation, X-ray diffraction, indoor accelerated test and theoretical analysis are used to carry out carbonation and erosion of hydraulic concrete materials. The performance degradation law under the action of dry and wet cycle is studied and some related parameters obtained from indoor accelerated test are extracted. Under different working conditions the stress and deformation laws of aqueduct structure are analyzed by using ANSYS three-dimensional finite element software. The main contents are as follows: (1) considering the practical construction requirements of hydraulic structure in irrigation area and the engineering application of high performance concrete mix ratio, the structural specimens with different mix ratio are designed, and the concrete residue collected in the field is ground. The main corrosion ions of concrete structure are determined by diffraction test in X-ray diffraction instrument. The reasonable corrosion environment and corrosion system are chosen to simulate the corrosion environment of local concrete structure in western China. The whole process of damage deterioration of concrete is studied. (2) the mass loss rate and the relative dynamic elastic modulus of the specimens are taken as the evaluation indexes, and the corrosion mode and water-cement ratio are studied. The influence of fly ash content on the durability of concrete, and the essence of concrete deterioration are explored. (3) the relevant data obtained from the test are extracted, and the elastic modulus and bulk density of reinforced concrete in aqueduct are treated in theory. The stress and deformation laws of aqueduct structures under different loads before and after coupled failure are studied by numerical analysis of aqueduct structures before and after coupling failure. The results show that carbonation can strengthen the surface layer of concrete, but the deterioration rate of concrete material is accelerated due to the change of chemical composition. When the content of fly ash is 20, the sulphate resistance of concrete reaches a relatively optimal state. Low water cement ratio and high water cement ratio can effectively hinder the erosion of ion penetration. After coupled failure, the increase of tensile stress, shear stress and displacement of aqueduct bent frame makes the local concrete structure crack more easily, especially in the coupling failure part, the increase range is very large, and it is easy to produce cracks. The research results provide a reference for the study of concrete durability and theoretical basis for the design of aqueduct structure and the operation and maintenance of aqueduct.
【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】：2015
【分类号】：TV431
本文编号：2314083
[Abstract]:The study of concrete durability is an important aspect in the field of material science. With the extensive use of concrete structures, the environment is becoming increasingly harsh, and the harm caused by environmental impact is increasing day by day. The severity of environmental conditions determines the length of life of concrete structures. The irrigation areas built in the west of China are concentrated in the inland river basins and the Loess Plateau. The special climate, geographical environment and regional water and salt migration caused by flood irrigation on the ground, the change of water level, cause carbonization and erosion of hydraulic concrete in irrigation areas. The damage rate of concrete structure is obviously higher than that in other parts of China. In the actual use environment, concrete structure may suffer from various complex environments, so it is necessary to strengthen the study of concrete deterioration law which is closer to the actual use environment. In the actual environment, many concrete structures will not only be destroyed by carbonation, erosion, dry-wet cycle, but also affected by environmental factors such as weight itself, design water level, increasing water level, crowd, wind and earthquake, etc. Therefore, it is of great significance to study the deterioration law of concrete under the action of many factors. In this paper, hydraulic concrete materials and U-shaped aqueduct structures are taken as typical research objects. The methods of field investigation, X-ray diffraction, indoor accelerated test and theoretical analysis are used to carry out carbonation and erosion of hydraulic concrete materials. The performance degradation law under the action of dry and wet cycle is studied and some related parameters obtained from indoor accelerated test are extracted. Under different working conditions the stress and deformation laws of aqueduct structure are analyzed by using ANSYS three-dimensional finite element software. The main contents are as follows: (1) considering the practical construction requirements of hydraulic structure in irrigation area and the engineering application of high performance concrete mix ratio, the structural specimens with different mix ratio are designed, and the concrete residue collected in the field is ground. The main corrosion ions of concrete structure are determined by diffraction test in X-ray diffraction instrument. The reasonable corrosion environment and corrosion system are chosen to simulate the corrosion environment of local concrete structure in western China. The whole process of damage deterioration of concrete is studied. (2) the mass loss rate and the relative dynamic elastic modulus of the specimens are taken as the evaluation indexes, and the corrosion mode and water-cement ratio are studied. The influence of fly ash content on the durability of concrete, and the essence of concrete deterioration are explored. (3) the relevant data obtained from the test are extracted, and the elastic modulus and bulk density of reinforced concrete in aqueduct are treated in theory. The stress and deformation laws of aqueduct structures under different loads before and after coupled failure are studied by numerical analysis of aqueduct structures before and after coupling failure. The results show that carbonation can strengthen the surface layer of concrete, but the deterioration rate of concrete material is accelerated due to the change of chemical composition. When the content of fly ash is 20, the sulphate resistance of concrete reaches a relatively optimal state. Low water cement ratio and high water cement ratio can effectively hinder the erosion of ion penetration. After coupled failure, the increase of tensile stress, shear stress and displacement of aqueduct bent frame makes the local concrete structure crack more easily, especially in the coupling failure part, the increase range is very large, and it is easy to produce cracks. The research results provide a reference for the study of concrete durability and theoretical basis for the design of aqueduct structure and the operation and maintenance of aqueduct.
【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】：2015
【分类号】：TV431
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