基于现场暴露试验与室内耐久性试验之间相关性的混凝土结构耐久性研究

发布时间：2018-05-15 21:36

本文选题：钢筋混凝土构件 + 室内试验　；参考：《南京航空航天大学》2014年博士论文

【摘要】：目前,国内外的混凝土结构耐久性设计,主要依赖于室内耐久性试验数据,或者基于实际工程环境的暴露试验数据,但是很少建立室内外耐久性之间的关系,因而,几乎对于所有的重点工程,进行耐久性设计时都需要有针对性的室内耐久性试验,在条件许可时偶尔进行一些有限的现场暴露试验。这样导致大量的重复试验,无谓的资源浪费,而且还不一定得出较为可靠的耐久性设计要求与设计建议等方面的重要结论。如果能够建立室内耐久性与现场实际工程耐久性之间联系的理论体系,今后就可以针对具体的工程环境资料,仅仅进行室内耐久性试验,根据已经建立的耐久性室内外关系进行混凝土结构的耐久性设计工作。为了能够很快地得到混凝土结构的室内外耐久性之间相关关系的规律,本文选用了混凝土结构失效较快的盐湖环境作为工程研究背景,系统研究了抗压强度等级为C30、C45FA30(C45掺加30%粉煤灰)、C45SG50(C45掺加50%矿渣)、C50、C60、C65SF10SG45(C65双掺10%硅灰+45%矿渣)、C70SF10FA27(C70双掺10%硅灰+27%粉煤灰)和C80SF10(C80掺加10%硅灰)的混凝土,在室内加速环境和盐湖现场暴露环境下的相同原料、相同配比、相同试件、相同时间、相同测试方法和相同评价标准的“六同时”耐久性试验。建立了混凝土构件的室内试验与室外试验的耐久性换算关系。提出了以室内长期浸泡环境为基准、利用室内外相关性系数为桥梁的混凝土结构耐久性设计的方法体系,利用三阶段寿命预测模型和相应的耐久性参数,对盐湖集团跨铁路专线大桥的主要结构构件进行了寿命设计。本文主要研究内容和结果如下:1)提出了以室内长期浸泡环境为基准、利用室内外相关性系数为桥梁的混凝土结构耐久性设计的新方法,建立了基于室内外相关性(correlation lab and field test,CLFT)的严酷环境下混凝土结构耐久性设计的方法体系,提出混凝土结构的室内标准试验与室外暴露试验耐久性数据之间的转换方法。2)研究了盐湖地区混凝土相对模量及表面剥落的变化规律。结果表明:与长期浸泡环境相比,施加荷载和干湿循环都加速了混凝土的劣化速度及表面剥落速度,干湿循环的效果更显著一些。混凝土劣化速度及表面剥落与混凝土强度等级有关,相同的腐蚀环境下,强度等级越高混凝土劣化速度越慢、腐蚀剥落开始的时间越晚。建立了预测盐湖现场、盐湖现场-干湿循环、盐湖现场-加载、盐湖现场-干湿循环-加载的混凝土相对动弹模量的时变方程。3)研究了盐湖地区混凝土氯离子扩散系数的室内外相关性规律。混凝土的氯离子结合能力与试验环境无关。室内加速环境下混凝土的表面自由氯离子含量与试验条件无关,混凝土在室内环境的表面自由氯离子含量大于其在现场暴露。表观自由氯离子扩散系数(D0)随着暴露时间的延长而降低。在混凝土配合比设计中,降低混凝土D0值的技术措施包括:提高混凝土强度等级和掺加矿物掺合料,其中,后者的降低效果更加明显,而且,大掺量矿物掺合料、双掺硅灰和粉煤灰或矿渣的降低效果非常显著。因此,盐湖地区高性能混凝土的设计原则是:应该优先采用大掺量矿物掺合料的单掺(C45FA30和C45SG50)或双掺(C65SF10FA27和C70SF10SG45)技术,而不是仅仅提高混凝土强度等级。4)研究了钢筋混凝土受弯构件的承载能力变化规律,建立了基于室内外相关性(CLFT)的结构承载力和挠度计算模型。建立了盐湖实体混凝土结构抗压强度的时变方程。建立了现场环境下钢筋混凝土结构内部钢筋锈蚀率和抗拉强度的时变方程。建立了基于室内外相关性的混凝土构件极限承载力和挠度的计算模型,并对实体工程进行了验证,数据显示计算结果与实测结果很接近,模型可以应用。5)结合可靠度理论和“诱导期+劣化期+失效期”三阶段寿命预测模型,利用本文建立的基于室内外相关性(CLFT)的设计方法,对混凝土结构承载力的计算模型进行修正。计算结果表明,在盐湖环境中,钢筋混凝土梁和柱的劣化期和诱导期均取决于腐蚀作用引起的混凝土劣化,其失效期取决于腐蚀引起的混凝土劣化作用以及钢筋锈蚀作用。当混凝土强度等级为C30~C60时,钢筋混凝土梁和柱的耐久性设计需要考虑诱导期和劣化期;采用混凝土强度等级为C65~C80时,钢筋混凝土梁和柱的耐久性设计仅需考虑诱导期。6)提供了在盐湖现场环境下采用不同配合比的混凝土构件寿命预测的算例。结果表明:当保护层厚度为30mm时,盐湖大气区的钢筋混凝土梁和柱要达到100a设计寿命,可采用强度等级在C65以上的高性能混凝土;当其设计寿命为50a时,可采用强度等级在C45~C60的高性能混凝土。在盐湖地区卤水与盐渍土环境下的钢筋混凝土梁和柱,要达到100a设计寿命,必须同时采用C50以上的高性能混凝土和表面附加防护措施(浸渍硅烷、喷涂氟碳涂料);当其设计寿命为50a时,仅仅采用C80SF10高性能混凝土即能满足设计要求。7)结合可靠度理论,研究基于室内外相关性的结构耐久性设计方法在严酷环境下实际桥梁工程结构的耐久性设计中的应用问题,并提供了算例。以盐湖集团跨铁路专线大桥为工程背景,对预制箱梁、盖梁、墩柱和条形扩大基础等主要结构部位进行了耐久性设计与寿命分析。结果表明:强度等级C50、主筋保护层厚度50mm的预制箱梁,要达到100a的设计寿命,必须对其腹板、翼板进行表面浸渍深度为2mm硅烷涂料的防护。强度等级C50、主筋保护层厚度60mm的盖梁,其服役寿命满足100a设计要求。对于强度等级C40、主筋保护层厚度60mm的墩柱,需要采用外包30mm钢板桩围堰+喷涂2次氟碳涂料的防护措施,才能达到100a的设计寿命。强度等级C50、主筋保护层厚度60mm的混凝土扩大基础,采取外包63mm钢板桩围堰防护+喷涂1次氟碳涂料的防护措施,其服役寿命能达到设计100a的要求。8)基于对盐湖地区预应力钢筋混凝土简支梁桥的耐久性优化设计,提出如下设计建议:预制箱梁腹板、翼板采用大掺量的矿物掺合料高性能混凝土且其保护层厚度为30mm,其服役寿命能达到设计100a的要求。预制箱梁和盖梁采用C50以上的高性能混凝土,其服役寿命能达到100a的设计要求。混凝土墩柱采用强度等级为C65~C70的高性能混凝土时,采取表面浸渍深度为2mm硅烷+外包30mm厚钢板桩围堰+喷涂1次氟碳涂料的防护方式,其服役寿命能达到100a的设计要求。混凝土条形扩大基础采用强度等级为C65的高性能混凝土,采取外包64mm厚钢板桩围堰+喷涂1次氟碳涂料的防护方式,其服役寿命能达到设计100a的要求。
[Abstract]:At present, the durability design of concrete structures at home and abroad is mainly dependent on the indoor durability test data, or the exposure test data based on the actual engineering environment, but rarely establishes the relationship between indoor and outdoor durability. Therefore, it is almost necessary for all key projects to be designed for durability design. A few limited field exposure tests are occasionally conducted when conditions permit. This leads to a large number of repeated tests, meaningless waste of resources, and not necessarily a more reliable conclusion of the durability design requirements and design proposals. In the future, the theoretical system of contact can be aimed at the specific engineering environment data, only indoor durability test, and durability design work of concrete structure is carried out according to the established durability indoor and outdoor relations. In order to get the law of the relationship between indoor and outdoor durability of concrete structure quickly, this paper chooses to choose the durability of concrete structure. The Saline Lake environment with fast failure of concrete structure is used as the engineering research background, and the compressive strength grade is C30, C45FA30 (C45 mixed with 30% fly ash), C45SG50 (C45 mixed with 50% slag), C50, C60, C65SF10SG45 (C65 double doped 10% silica fume +45% slag), C70SF10FA27 (C70 double doped 10% silica ash fly ash) and mixture of 10% silica fume. Soil, the same raw material, the same ratio, the same test parts, the same time, the same test method and the same evaluation standard "six Simultaneity" endurance test under the indoor accelerated environment and the exposure environment of Saline Lake. The relationship between the indoor test of the concrete component and the durability of the outdoor test was established. The indoor long-term immersion ring was put forward. On the basis of the three stage life prediction model and the corresponding durability parameters, the three stage life prediction model and the corresponding durability parameters are used to design the durability of the concrete structure of the bridge. The main contents and results of this paper are as follows: 1) the main contents and results are as follows. A method system for durability design of concrete structures under the harsh environment of correlation lab and field test (CLFT) is established by using the internal and external environment as a benchmark and a new method of durability design for concrete structures in the interior and exterior correlation coefficient as a bridge. The indoor standard test and room of concrete structure are put forward. The changing law of the concrete relative modulus and surface exfoliation in the Saline Lake area is studied by the conversion method.2 between the durability data of the external exposure test. The results show that the deterioration speed and the surface exfoliation speed of concrete are accelerated, and the effect of dry and wet cycle is more significant compared with the long-term immersion environment. The deterioration rate and surface exfoliation are related to the strength grade of concrete. Under the same corrosion environment, the higher the strength grade is, the slower the deterioration speed of concrete is, the more late the corrosion exfoliation begins. The relative dynamic modulus of concrete is established to predict the Saline Lake site, the Saline Lake site dry wet cycle, Saline Lake site loading, the on-site wet cycle and the wet cycle loading. The indoor and external correlation law of the chloride ion diffusion coefficient in the Saline Lake area is studied in the Saline Lake area. The chlorine ion binding capacity of concrete is independent of the test environment. The content of free chlorine ion on the surface of concrete under indoor accelerated environment is independent of the test conditions, and the content of free chlorine ion on the surface of concrete is greater than that of the concrete in the indoor environment. The apparent free chlorine ion diffusion coefficient (D0) decreases with the prolongation of exposure time. In the concrete mix ratio design, the technical measures to reduce the D0 value of concrete include: improving the concrete strength grade and adding mineral admixture, among which the latter has a more obvious reduction effect, and a large amount of mineral admixture is mixed with silicon. The reduction effect of ash and fly ash or slag is very significant. Therefore, the design principle of high performance concrete in Saline Lake area is that the single admixture (C45FA30 and C45SG50) or double admixture (C65SF10FA27 and C70SF10SG45) technology of large amount mineral admixture should be preferred, and not only the high concrete strength grade.4) is used to study the flexural structure of reinforced concrete. The load carrying capacity change law of the part is established, and the calculation model of the structural bearing capacity and deflection based on CLFT is established. The time variation equation of the compressive strength of the concrete structure of Saline Lake is established. The time variation equation of the corrosion rate and tensile strength of the reinforced concrete structure in the field environment is established. The calculation model of the ultimate bearing capacity and deflection of the concrete members is verified, and the data show that the calculated results are close to the measured results. The model can be applied to the three stage life pretest model of the reliability theory and the three stage of the "induction period + deterioration period + failure period", which is based on the indoor and outdoor correlation established in this paper. The calculation model of concrete structure bearing capacity is modified by the design method of CLFT. The calculation results show that the deterioration period and induction period of reinforced concrete beams and columns in the Saline Lake environment all depend on the deterioration of concrete caused by corrosion, and the failure period depends on the deterioration of concrete caused by corrosion and the corrosion of steel bars. When the concrete strength grade is C30~C60, the durability design of the reinforced concrete beams and columns needs to consider the induction period and the deterioration period. When the concrete strength grade is C65~C80, the durability design of the reinforced concrete beams and columns only needs to consider the induction period.6), which provides the life of the concrete members with different mix ratio under the Saline Lake environment. The calculation example shows that when the thickness of the protective layer is 30mm, the reinforced concrete Liang Hezhu of the Saline Lake atmosphere will reach the 100A design life, and the high performance concrete with the strength grade above C65 can be used. When the design life is 50a, the high performance concrete with the strength grade in the C45~C60 can be used. The brine and the saline soil ring in the Saline Lake area can be used. In order to achieve 100A design life, it is necessary to use high performance concrete and surface additional protective measures above C50 (impregnated silane, spraying fluorocarbon coating) at the same time for 100A design life. When its design life is 50a, only C80SF10 high performance concrete can meet the design requirements.7) combined with the reliability theory and Study on the room based on the reliability theory. The internal and external structural durability design method is applied to the durability design of the actual bridge engineering structure under the harsh environment, and provides an example. Taking the Saline Lake group Cross railway bridge as the engineering background, the durability design and life of the prefabricated box girder, the cover beam, the pier column and the bar shaped base are carried out for durability design and life. Analysis. The results show that the prefabricated box girder with the strength grade C50 and the thickness of the main protection layer is 50mm. To achieve the design life of 100A, the surface impregnation depth of its web and the wing plate must be protected by the 2mm silane coating. The strength grade C50 and the thickness 60mm of the main bar protection layer can meet the 100A design requirements. For the strength grade C40, the main strength grade C40 is the master. The pier column with the thickness of 60mm is required to adopt the protective measures of outsourcing 30mm steel sheet pile cofferdam + 2 fluorocarbon coating to achieve the design life of 100A. The strength grade C50, the expansion foundation of the concrete with the thickness of the main bar protection layer 60mm, the protective measures for the protection of the outsourced 63mm steel sheet pile cofferdam + spray coating of the fluorocarbon coating, and the service life of the coating. 100A requirement.8) based on the durability optimization design of prestressed concrete simple supported beam bridge in Saline Lake area, the following design suggestions are put forward: Prefabricated Box Girder Web, wing plate with high content of mineral admixture of high performance concrete and its protective thickness of 30mm, its service life can meet the requirements of design 100A. Precast box girder The service life of the high performance concrete above C50 can reach the design requirement of 100A. When the concrete pier column adopts the high performance concrete with the strength grade of C65~C70, the protection mode of the surface impregnation depth of 2mm silane + outsourced 30mm thick steel sheet pile cofferdam + spraying 1 fluorocarbon coatings is adopted, and the service life of the concrete pier can reach the design of 100A. It is required that the reinforced concrete strip foundation adopt high performance concrete with the strength grade of C65, and adopt the protection mode of outsourcing 64mm thick steel sheet pile cofferdam + spraying 1 times fluorocarbon coating, and its service life can meet the requirement of design 100A.

【学位授予单位】：南京航空航天大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU375

【共引文献】