初始损伤对混凝土硫酸盐腐蚀劣化性能的影响
发布时间：2019-01-18 19:00
【摘要】：通过试验研究含初始损伤混凝土在硫酸盐腐蚀和干湿循环共同作用下的性能,分析了不同初始损伤程度混凝土随腐蚀时间的增加,其质量、超声波传播速度、强度、单轴压缩应力应变曲线以及声发射活动的变化,运用损伤力学对腐蚀损伤进行定量评价和参数拟合,基于声发射特性建立含初始损伤混凝土的腐蚀受荷损伤模型并进一步分析其损伤演化过程,借助环境扫描电镜与电子能谱技术观测分析受硫酸盐腐蚀作用初始损伤混凝土微结构的变化,揭示其损伤机理.试验结果表明,随着腐蚀时间的增加,不同初始损伤程度混凝土的质量、超声波传播速度和强度均呈先增大后减小,初始损伤程度增加会加速混凝土在腐蚀作用下物理力学性能的劣化,其影响存在阈值,分别以抗压强度、超声波速为损伤变量可以建立混凝土的腐蚀损伤劣化方程,并进一步得出不同损伤表达式间的函数关系;相同腐蚀时间下,初始损伤的增加使声发射活动减弱且产生明显的声发射的时间滞后;初始损伤下,基于声发射特性的混凝土损伤演化过程可分为初期压密阶段、损伤稳定演化阶段和损伤加速发展阶段3个阶段;初始损伤的增加使混凝土内部腐蚀反应更为活跃,微裂纹网络体系比无初始损伤状态下更加发达,呈现龟裂状延伸和扩展,进而改变了混凝土的宏观物理力学性质.
[Abstract]:The performance of concrete with initial damage under the combined action of sulphate corrosion and wet and dry cycle is studied by experiments. The mass, ultrasonic propagation speed and strength of concrete with different initial damage degree are analyzed with the increase of corrosion time. The stress and strain curves of uniaxial compression and the change of acoustic emission activity are used to quantitatively evaluate and fit the corrosion damage by damage mechanics. Based on the characteristics of acoustic emission, the damage model of concrete with initial damage is established and the damage evolution process is further analyzed. By means of environmental scanning electron microscopy (ESEM) and electron energy dispersive spectroscopy (EDS), the microstructures of initial damage concrete subjected to sulphate corrosion were observed and analyzed, and the damage mechanism was revealed. The experimental results show that with the increase of corrosion time, the mass, ultrasonic velocity and strength of concrete with different initial damage degree increase first and then decrease. The increase of initial damage degree will accelerate the deterioration of physical and mechanical properties of concrete under corrosion, and there are threshold values for its influence. The equation of corrosion damage deterioration of concrete can be established by using compressive strength and ultrasonic speed as damage variables respectively. Furthermore, the functional relationships among different damage expressions are obtained. At the same corrosion time, the increase of initial damage weakens the acoustic emission activity and lags the time of producing obvious acoustic emission. Under initial damage, the damage evolution process of concrete based on acoustic emission characteristics can be divided into three stages: initial compression stage, damage stable evolution stage and damage accelerated development stage. The increase of initial damage makes the internal corrosion reaction of concrete more active, and the micro-crack network system is more developed than that without initial damage state, which shows crack extension and propagation, and then changes the macroscopic physical and mechanical properties of concrete.
【作者单位】： 北京科技大学土木与资源工程学院;
【基金】：国家重点研发计划资助项目(2016YFC0600800) 国家自然科学基金资助项目(51678049)
【分类号】：TU528
，
本文编号：2411015
[Abstract]:The performance of concrete with initial damage under the combined action of sulphate corrosion and wet and dry cycle is studied by experiments. The mass, ultrasonic propagation speed and strength of concrete with different initial damage degree are analyzed with the increase of corrosion time. The stress and strain curves of uniaxial compression and the change of acoustic emission activity are used to quantitatively evaluate and fit the corrosion damage by damage mechanics. Based on the characteristics of acoustic emission, the damage model of concrete with initial damage is established and the damage evolution process is further analyzed. By means of environmental scanning electron microscopy (ESEM) and electron energy dispersive spectroscopy (EDS), the microstructures of initial damage concrete subjected to sulphate corrosion were observed and analyzed, and the damage mechanism was revealed. The experimental results show that with the increase of corrosion time, the mass, ultrasonic velocity and strength of concrete with different initial damage degree increase first and then decrease. The increase of initial damage degree will accelerate the deterioration of physical and mechanical properties of concrete under corrosion, and there are threshold values for its influence. The equation of corrosion damage deterioration of concrete can be established by using compressive strength and ultrasonic speed as damage variables respectively. Furthermore, the functional relationships among different damage expressions are obtained. At the same corrosion time, the increase of initial damage weakens the acoustic emission activity and lags the time of producing obvious acoustic emission. Under initial damage, the damage evolution process of concrete based on acoustic emission characteristics can be divided into three stages: initial compression stage, damage stable evolution stage and damage accelerated development stage. The increase of initial damage makes the internal corrosion reaction of concrete more active, and the micro-crack network system is more developed than that without initial damage state, which shows crack extension and propagation, and then changes the macroscopic physical and mechanical properties of concrete.
【作者单位】： 北京科技大学土木与资源工程学院;
【基金】：国家重点研发计划资助项目(2016YFC0600800) 国家自然科学基金资助项目(51678049)
【分类号】：TU528
，
本文编号：2411015
本文链接：https://www.wllwen.com/kejilunwen/huaxuehuagong/2411015.html
