水工混凝土在多因素耦合作用下的性能劣化規(guī)律研究
發(fā)布時間：2018-11-06 11:01
【摘要】：混凝土耐久性研究是材料科學(xué)研究領(lǐng)域的一個重要方面,隨著混凝土結(jié)構(gòu)的廣泛使用,使用環(huán)境日益嚴(yán)酷,其受到環(huán)境影響的危害性也日益增加,環(huán)境條件的嚴(yán)酷程度決定了混凝土結(jié)構(gòu)工程壽命的長短。我國西部建成的灌區(qū)集中分布在內(nèi)陸河流域和黃土高原地區(qū),特殊的氣候、地理環(huán)境以及地面大水漫灌引起的區(qū)域水鹽運移、水位變化,造成灌區(qū)水工混凝土受到碳化、侵蝕、干濕循環(huán)等破壞作用,導(dǎo)致混凝土結(jié)構(gòu)損傷劣化速度明顯高于我國其它地區(qū)。在實際使用環(huán)境下,混凝土結(jié)構(gòu)可能遭受各種各樣的復(fù)雜環(huán)境,需要加強更加貼近實際使用環(huán)境的混凝土劣化規(guī)律研究,在實際使用環(huán)境中有相當(dāng)多的混凝土結(jié)構(gòu)不僅會受到碳化、侵蝕、干濕循環(huán)等破壞作用,還會受到自重本身、設(shè)計水位、加大水位、人群、風(fēng)和地震等環(huán)境因素的影響,因此對混凝土多因素作用下的劣化規(guī)律研究具有深遠(yuǎn)意義。本文以水工混凝土材料和U型渡槽結(jié)構(gòu)為典型研究對象,采用現(xiàn)場調(diào)查、X光衍射、室內(nèi)加速試驗、理論分析的研究方法開展水工混凝土材料在碳化、侵蝕、干濕循環(huán)作用下的性能劣化規(guī)律研究,提取室內(nèi)加速試驗得到的部分相關(guān)參數(shù),在不同工況組合下,利用ANSYS三維有限元軟件對渡槽結(jié)構(gòu)進(jìn)行應(yīng)力和變形規(guī)律分析。主要內(nèi)容如下:(1)考慮灌區(qū)水工結(jié)構(gòu)的實際施工要求與高性能混凝土配合比的工程應(yīng)用,設(shè)計不同配合比的結(jié)構(gòu)試件,將現(xiàn)場采集的混凝土殘渣磨碎,在X衍射儀器中做衍射試驗,確定混凝土結(jié)構(gòu)的主要侵蝕離子,選擇合理的腐蝕環(huán)境和腐蝕制度模擬我國西部當(dāng)?shù)鼗炷两Y(jié)構(gòu)所處的腐蝕環(huán)境,研究混凝土損傷劣化全過程。(2)綜合試驗數(shù)據(jù)和理論分析,以試件的質(zhì)量損失率和相對動彈性模量為評價指標(biāo),研究腐蝕方式、水灰比、粉煤灰摻量對混凝土耐久性能衰減的影響,探尋混凝土劣化本質(zhì)。(3)提取試驗所得到的相關(guān)數(shù)據(jù),在理論上對渡槽鋼筋混凝土的彈性模量、容重等材料特性進(jìn)行等效處理,對耦合破壞作用前后的渡槽結(jié)構(gòu)進(jìn)行數(shù)值分析,研究渡槽排架在耦合破壞作用前后不同荷載組合下渡槽結(jié)構(gòu)的應(yīng)力和變形規(guī)律。研究結(jié)果表明:碳化雖然能夠密實混凝土表層,但由于化學(xué)成分的改變,混凝土材料劣化速度反而加快,粉煤灰摻量為20%時,混凝土抗硫酸鹽性能達(dá)到相對較優(yōu)化的狀態(tài),低水灰比較高水灰比可有效地阻礙侵蝕離子滲透。渡槽排架在耦合破壞作用后,拉應(yīng)力、切應(yīng)力和位移的增加更易使局部混凝土結(jié)構(gòu)產(chǎn)生開裂的現(xiàn)象,特別在耦合破壞部位,增長幅度很大,極易產(chǎn)生裂縫。研究成果為混凝土耐久性能研究提供參考,為渡槽結(jié)構(gòu)設(shè)計和運行過程中的使用維護(hù)提供理論依據(jù)。
[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.
【學(xué)位授予單位】：華北水利水電大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TV431
本文編號：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.
【學(xué)位授予單位】：華北水利水電大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TV431
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