矿山腐蚀环境中混凝土材料结构性能劣化机理试验研究

发布时间：2018-02-04 00:01

本文关键词： 矿山腐蚀环境混凝土结构性能劣化机理腐蚀状态评价　出处：《北京科技大学》2016年博士论文　论文类型：学位论文

【摘要】：矿山工程中混凝土结构构件的特点是：服役周期长,受力复杂,同时还长期遭受复杂有害环境的化学腐蚀。而矿山腐蚀环境中,地下结构混凝土在应力与腐蚀耦合作用下,混凝土材料强度会逐渐劣化,致使材料局部发生损伤。当损伤累计到一定程度,混凝土构件就会发生局部或全部破坏,从而影响结构构件在运营期间的服役安全性和服役年限,降低结构耐久性。本文以淮北矿业股份有限公司临涣煤矿委托项目为依托,针对矿区地下混凝土结构所处的特殊环境,在现场调查的基础上,采用试验研究、数值分析、理论分析和数值模拟方法,重点研究了矿山腐蚀环境下混凝土构件的硫酸盐侵蚀机理、强度损伤劣化规律、断裂演化规律、钢筋与混凝土粘结退化性能以及腐蚀混凝土在抗压及断裂过程中声发射信号特征,提出基于声发射表征的矿区混凝土破坏过程的损伤劣化模型。研究内容及结论如下：(1)对实验室配置的混凝土试样进行了三因素四水平的人工加速硫酸盐腐蚀试验,测试了不同腐蚀时间下的不同初始损伤、不同养护龄期和不同硫酸盐浓度作用下混凝土的抗压强度,并以抗压强度为指标定义了腐蚀混凝土损伤度,建立了损伤度分别与环境中硫酸盐溶液浓度、初始损伤、养护龄期与应力之间的函数关系,并给出三因素综合影响下的损伤度计算模型。(2)不同初始损伤、不同腐蚀溶液浓度和不同养护龄期的混凝土在受硫酸盐溶液侵蚀后抗压强度总体上表现为先增大后减小的趋势,而质量则是呈现出先降低后增加的趋势。研究发现初始损伤越大的混凝土,腐蚀前期抗压强度增加越快,同样,腐蚀后期抗压强度也下降的幅度越大。养护龄期28天的混凝土在受腐蚀期间,强度一直高于低养护龄期的混凝土强度。(3)通过三点弯曲梁加速腐蚀试验发现,混凝土断裂时刻的峰值荷载受硫酸盐影响较大。峰值荷载随腐蚀时间延长其降低幅度增大,同时断裂过程中线弹性段越小,越易进入到塑性区,从而加快断裂进程。混凝土切口梁试件在不同浓度硫酸盐溶液浸泡过程中,断裂韧度整体表现为先增大后降低的趋势,降低幅度随硫酸盐浓度增大而增大。(4)分析了不同腐蚀溶液浓度、不同初始损伤、不同养护龄期和不同浸泡时间下腐蚀混凝土抗压过程中声发射信号特征,以及不同腐蚀时间、不同种类混凝土断裂过程声发射信号特征。用声发射活性函数估计腐蚀损伤因子,建立腐蚀混凝土损伤劣化方程,定量描述腐蚀混凝土损伤对混凝土力学性能的影响,发现有初始损伤的混凝土在受硫酸盐侵蚀后,腐蚀损伤因子在加载过程中发展速度快于浸泡前无初始损伤的混凝土(5)钢筋混凝土试件经过720天硫酸盐侵蚀,变形钢筋与腐蚀混凝土之间的极限粘结强度先增加后降低,随着腐蚀时间的延长,降低速率在持续增加。掺入仿钢纤维的钢筋混凝土试件在硫酸盐腐蚀条件下极限粘结强度高于未掺入仿钢纤维的钢筋混凝土试件。(6)利用灰色理论预测了不同腐蚀因素和不同腐蚀水平下混凝土腐蚀强度。运用数值模拟分析了目前腐蚀混凝土构件的受力状态,评价了其服役状况。
[Abstract]:The characteristics of concrete structure in the mine engineering service is: long cycle, complex force, and has long suffered from complex chemical corrosion are harmful to the environment. And mine corrosion environment, underground stress and corrosion in concrete structure under coupling strength of concrete materials will deteriorate gradually, resulting in local material damage. When the cumulative damage to a certain extent, will be concrete in partial or total destruction, thus affecting the structure during operation of service safety and service life, reduce the durability of the structure. In this paper, taking Huaibei mining Limited by Share Ltd commissioned in Linhuan coal mine project, according to the special environment of underground concrete structure mining area, based on the field investigation, the experimental study and numerical analysis, theoretical analysis and numerical simulation, focusing on mining under corrosive environment of concrete sulfate erosion The mechanism of damage and deterioration of strength, fracture evolution, the bond between reinforcement and concrete performance degradation and corrosion of concrete in compression and fracture process characteristics of acoustic emission signals, proposed damage deterioration model of mine concrete damage process based on acoustic emission characterization. Research contents and conclusions are as follows: (1) the accelerated sulphate corrosion test three factors and four levels of laboratory concrete specimens of configuration, different initial damage under different etching time of the test, the compressive strength of the concrete effect of different curing time and different sulfate concentrations, and the definition of corrosion damage of concrete with compressive strength as the index, the damage degree and sulfate concentration in the environment. The initial damage, curing period and function should be the relation between force, calculation model of damage degree three factors and gives the different initial loss (2). Injury, different corrosion solution concentration and different curing period of concrete in sulfate solution after the erosion of the compressive strength of the overall performance of the first increased and then decreased, while the quality is decreased first and then increased. The study found that the greater the initial damage of concrete, corrosion early compressive strength increased more quickly, the same later, the compressive strength of corrosion also decrease more. The curing period of 28 days in concrete due to corrosion during the strength has been higher than the low strength of concrete curing period. (3) through three point bending beam accelerated corrosion test showed that the peak load of concrete mixed fracture time by sulfate influence. The peak load reduce the amplitude increases with prolonging corrosion time, the fracture process of linear elastic section of smaller, more easily into the plastic zone, thus speeding up the process of fracture. The concrete notched beam specimens at different concentrations of sulfuric acid leaching solution Global process, the fracture toughness of the overall performance is first increased and then decreased, with the reduction of sulfate concentration increases. (4) different corrosion solution concentration was analyzed, different initial damage, the AE signal characteristics of corrosion of concrete compressive process of different curing time and different soaking time in different time and different corrosion. Type of fracture process of concrete AE. Estimation of the corrosion damage factor by acoustic emission activity function, establishment of corrosion damage of concrete deterioration equation, the quantitative description of corrosion damage of concrete on concrete mechanical properties, found the initial damage of concrete under sulfate corrosion, corrosion damage factor in the loading process is faster than immersion before the initial damage of concrete (5) reinforced concrete specimens after 720 days of sulphate erosion, deformation limiting viscosity between reinforcement and corrosion of concrete Node strength first increased and then decreased, with the prolongation of corrosion time, reduce the rate continued to increase. The incorporation of steel fiber reinforced concrete imitation specimens under sulfate corrosion under the condition of ultimate bond strength is higher than that of reinforced concrete mixed with steel fiber not imitation specimens. (6) the different corrosion factors and corrosion of concrete under different level the pre corrosion strength by using grey theory. By numerical simulation analyzes the corrosion of concrete stress state, evaluate its service status.

【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TD26;TU37

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