【摘要】：近年來,混凝土材料在土木工程領域得到廣泛應用,受服役環(huán)境的影響,眾多混凝土結(jié)構(gòu)未達到設計壽命而發(fā)生侵蝕破壞。在我國西北干旱揚黃灌區(qū),水工混凝土建筑物同時受到碳化、硫酸鹽侵蝕、干濕循環(huán)等作用,出現(xiàn)了不同程度的侵蝕破壞,灌區(qū)安全運行受到極大威脅。在灌區(qū)混凝土在多種侵蝕作用下,耐久性劣化機理尚不明確,劣化過程規(guī)律尚不清晰,水工混凝土材料層次的耐久性綜合評價方法仍不夠完善。因此,開展在碳化、硫酸鹽侵蝕、干濕循環(huán)共同作用下的混凝土耐久性劣化規(guī)律研究與綜合評價將更有學術價值與應用價值。本課題結(jié)合河南省高�？萍紕�(chuàng)新人才支持計劃項目“基于多場耦合作用的灌區(qū)水工混凝土結(jié)構(gòu)耐久性研究”實施開展。以甘肅省景泰川電力提灌區(qū)(以下簡稱“景電灌區(qū)”)內(nèi)的水工混凝土建筑物為研究對象,針對水工混凝土結(jié)構(gòu)服役環(huán)境中的水樣、土樣和剝落殘渣進行成分分析,揭示主要侵蝕作用及侵蝕介質(zhì);設計不同水膠比、粉煤灰摻量、引氣劑用量的混凝土,進行室內(nèi)加速劣化試驗,揭示了混凝土的耐久性劣化過程;基于灰色關聯(lián)理論和可拓評價理論,對各侵蝕階段的混凝土耐久性進行了定量評價和定性評價,得出以下結(jié)論:(1)在碳化-硫酸鹽侵蝕-干濕循環(huán)共同作用下,不同配合比混凝土的耐久性劣化過程整體上經(jīng)歷了稍有增強-緩慢下降-快速下降三個階段。水膠比對混凝土的耐久性影響較為顯著,水膠比越小,耐久性越強,劣化過程越慢。粉煤灰的摻加能夠明顯提高混凝土的耐久性,最優(yōu)摻量在20%左右。引氣劑的使用在一定程度上能夠提高混凝土的耐久性。(2)以關聯(lián)度值為依據(jù)將混凝土耐久性等級劃分為“好、較好、中、較差、差”五個等級。在實驗前期,各試驗組混凝土耐久性關聯(lián)度值在0.75以上,等級均在“Ⅱ”級以上,耐久性整體處于“較好”以上狀態(tài);在實驗后期,各試驗組混凝土耐久性關聯(lián)度值在0.45以下,等級均在“Ⅴ”級以下,耐久性整體處于差的狀態(tài)。通過碳化-硫酸鹽侵蝕-干濕循環(huán)共同作用下混凝土耐久性劣化規(guī)律研究和綜合評價,為干旱揚黃灌區(qū)水工混凝土結(jié)構(gòu)的耐久性設計提供參考,對現(xiàn)有混凝土建筑物的運行維護與修繕提供了依據(jù)。
[Abstract]:In recent years, concrete materials have been widely used in the field of civil engineering. Under the influence of service environment, many concrete structures have not reached the design life and have been corroded and destroyed. In the arid Yellow River irrigation area of northwest China, the hydraulic concrete buildings are affected by carbonation, sulfate erosion and dry-wet cycle at the same time, which results in different degree of erosion and destruction, and the safe operation of the irrigation area is greatly threatened. Under the action of many kinds of erosion in irrigation area, the mechanism of durability deterioration is not clear, the law of deterioration process is not clear, and the comprehensive evaluation method of durability of hydraulic concrete material level is not perfect. Therefore, the research and comprehensive evaluation of durability deterioration law of concrete under the combined action of carbonation, sulfate erosion and dry-wet cycle will have more academic value and application value. This subject is carried out in combination with the project "durability study of hydraulic concrete structure in irrigation district based on multi-field coupling", which is supported by scientific and technological innovation talents in colleges and universities in Henan Province. Taking the hydraulic concrete buildings in Jingtai Electric Irrigation area (hereinafter referred to as Jingdian Irrigation area) as the research object, the composition analysis of water, soil and peeling residue in the service environment of hydraulic concrete structure is carried out. Reveal the main erosion and erosion medium; Concrete with different water / binder ratio, fly ash content and air entraining agent was designed, and accelerated deterioration test was carried out to reveal the durability deterioration process of concrete. Based on the grey relation theory and extension evaluation theory, the durability of concrete in each erosion stage is evaluated quantitatively and qualitatively. The following conclusions are drawn: (1) under the combined action of carbonation, sulphate erosion and dry and wet cycle, the concrete durability is evaluated quantitatively and qualitatively. The durability deterioration process of concrete with different mix ratio has experienced three stages as a whole: slight strengthening, slow descending and fast decreasing. The water / binder ratio has a significant effect on the durability of concrete. The smaller the water-binder ratio is, the stronger the durability is, and the slower the deterioration process is. The addition of fly ash can obviously improve the durability of concrete, and the optimum content is about 20%. The use of air-entraining agent can improve the durability of concrete to a certain extent. (2) according to the correlation value, the durability grade of concrete can be divided into five grades: "good, medium, poor and poor". In the early stage of the experiment, the concrete durability correlation degree of each test group is above 0.75, the grade is above "鈪，

本文編號：2380378