人工环境中模拟海洋潮汐作用的试验装置

介绍一种人工环境中模拟海洋潮汐作用的混凝土耐久性试验装置。该装置包括潮汐控制系统、温湿度控制系统、吹风控制系统、试验箱体和控制器。试验箱体与吹风控制系统、温湿度控制系统、潮汐控制系统相连;放置试件的腐蚀水槽置于试验箱体内,通过潮汐控制系统与试验箱体外部的保温盐水池相连;吹风系统、温湿度控制系统和潮汐控制系统分别与控制器相连。该装置不但可以自动模拟潮汐作用,还可以精确控制潮汐过程中的温度、湿度和风速条件,并且结构简单、自动化程度高、稳定性强、自身耐久性好。试验结果表明,该装置可以满足不同海洋环境的潮汐作用模拟。     

人工海洋环境试验装置控制系统优化设计

针对现有试验装置需要大量人为参与的半自动化特点,以及试验周期长且重现性差的问题,通过为红外光照子系统、温湿度控制子系统、通风控制子系统和潮汐控制子系统设计鲁棒性控制策略,实现恶劣环境下干湿时间、吹风时间、潮汐水位等环境参数的准确追踪和控制;在系统总控制器中提出环境自适应优化控制策略,实现各个子系统之间的协调和工序优化,加速耐久性试验过程,实现潮汐模拟过程中人工环境条件的准确控制,同时具有较经济的成本和较好的可维护性、扩展性,有助于展开不同海洋环境条件下的耐久性试验。     

Effect of chloride content on bond behavior between FRP and concrete

For reinforced concrete structures located along the seaside, the penetration of chloride ions into concrete may be a threat to the durability of the structures. Experimental investigations were carried out to study the effect of chloride content on the bond behavior between concrete and fiber reinforced polymer (FRP) plates. Direct shear tests were conducted on the FRP strengthened concrete members. Before testing, the specimens were immersed in NaCl solutions with concentrations ranging from 3%—15% for different time (0—120 d). Then, the specimens were dried and tested to obtain the initial and ultimate debonding loads, together with strain distributions along the FRP plates of different load values. The correlations between chloride content and debonding parameters are established. Test results show that the debonding parameters are closely related to the immersing time rather than the chloride content of the solution.     

瑞安市部分混凝土结构腐蚀破坏状况调查与原因分析

对瑞安市教座典型的混凝土结构构筑物的腐蚀破坏状况进行了调查分析．结果表明,飞云江沿岸混凝土结构腐蚀比较严重,许多构筑物的混凝土保护层过薄,有的出现了内部钢筋锈蚀、混凝土顺筋开裂和剥落等现象．主要原因有结构设计不合理、施工质量差、化学侵蚀等．     

混凝土温度场差分法求解精度研究

With the finite difference method to calculate the temperature distribution in mass concrete structures, the solution precision will increase with a smaller step size, at the cost of computational time. In view of the basic characteristics of the finite difference method, a simple yet powerful improvement is introduced. By multiplying the adiabatic temperature function with a correction factor, the precision of the solution can be assured without an increase in the computation time. In addition, the correction rules for three types of commonly used concrete hydration formulas are investigated.     

Chloride content and pH value in the pore solution of concrete under carbonation

Chloride content and the pH value of the pore solution in the neighborhood of steel reinforcement are decisive parameters for initiation and rate of corrosion. The pore solution of cement mortar and hardened cement paste has been expressed from the pore space by high pressure in the investigation. The influence of the water-cement ratio, age, and addition of chloride to the fresh mix on chloride content in the pore solution has been determined by ion chromatography. At the same time the pH value of the pore solution has been determined. The dissolved chloride content decreases with increase in the water-cement ratio. The amount of bound chloride increases with time, but it decreases with decreasing content of dissolved chloride in the pore solution. A significant influence of carbonation on the dissolved chloride content of the pore solution has been observed. With complete carbonation, the dissolved chloride content in cement mortar and hardened cement paste increases by a factor between 2 and 12. The bound chloride decreases by 27%-4%. As expected, the pH value decreases from around 13.2 to as low as 8.0 due to carbonation. It can be concluded that carbonation not only lowers the pH value but liberates bound chloride. This is one obvious reason why the combined action of chloride penetration and carbonation accelerates steel corrosion and shortens the service life of reinforced concrete structures.     

聚丙烯纤维对高性能混凝土强度与耐久性影响的试验研究

研究了掺加聚丙烯纤维、矿渣及粉煤灰对C50高性能混凝土抗渗性、立方体抗压强度、干燥收缩变形以及抗氯离子渗透性能的影响,同时分析了聚丙烯纤维的合理掺量。     

Shear Strength of Reinforced Concrete Beams Under Sea Water

The marine structures such as harbour,pier and inshore concrete terrace are exposed in adverse circumstances in a long period of time . Owing to the attack of external corrosive medium, their safety, durability and reliability decline. Especially the reinforced concrete(RC) structures in the wave splash area are more likely to be subjected to destruction and the loss is vast. Now the safety ,durability and reliability of structure have become increasingly an important subject to be studied. By way of the soaking and drying cycle test on the different mix proportions oblique section of 10 pieces of RC beams suffered artificial sea water(ASW) corrosion under 0,35,70,105,140 times of dry-wet cycles, the compared results of exerting pressure test of these beams under simply supporting were investigated. The law about the changes of the mechanical performance for RC beams with different mix proportions under different time periods for suffering corrosion of dry-wet cycles is as follows: the resistivity to ASW corrosion of the concrete specimens with various water cement ratio(various initial strength) is different ; the characters of oblique section failure for RC beams attacked by sea water are about the same as those for ordinary RC beam; along with the extension of the time for sea water attack, the bearing capacity for oblique section of RC beams varies wave upon wave. The specimens attacked by sea water for about 35 times of corrosion cycle achieve minimum bearing capacity.     

Laboratory test on long-term deterioration of cement soil in seawater environment

Laboratory tests were conducted to study the effects of curing time, cement ratio and seawater pressure on cement soil deterioration formed at simulative marine soft clay sites. Deterioration depth was determined on the basis of characteristics of penetration resistance and penetration depth curves, and the deterioration depth of cement soil with the cement ratio of 7%, reached 31.8 mm after 720 d. Results of research indicated that deterioration extended quickly under seawater environment and the deterioration depth increased with the prolonging curing time. In addition, the water pressure could speed up deterioration. With the increase of cement content, the strength of cement soil increased obviously. At the same time, the deterioration depth decreased significantly. The concentration of calcium ion in the cement stabilized soil increased with the increase of depth, while that of magnesium ion gradually decreased. The variations were consistent with energy dispersive spectrometer(EDS)analysis results, and the calcium concentration with depth was in a good consistency with strength distribution at long term. The results showed that the deterioration became more serious with the curing time, and it was related to calcium leaching.     

多用途混凝土抗氯离子渗透性测定仪的研制及应用

该多用途混凝土抗氯离子渗透性测定仪基于计算机系统的USB总线和虚拟仪器的方法研制，可依照ASTMC1202．97规范和依据Nemst-Einstein方程原理建立的NEL方法，分别通过测定在规定时间内通过混凝土的总电量和混凝土的氯离子扩散系数来快速评定混凝土的抗氯离子渗透性。试验结果表明：该设备可依照相应的规范和方法，精确地完成对混凝土抗氯离子渗透性的评价，同时该设备还具有安全性高，可移植性好和扩展能力强的特点。     

Assessment of Containment Structures Against Missile Impact Threats

In order to ensure the highest safety requirements, nuclear power plant structures (the containment structures, the fuel storages and transportation systems) should be assessed against all possible internal and external impact threats. The internal impact threats include kinetic missiles generated by the failure of high pressure vessels and pipes, the failure of high speed rotating machineries and accidental drops. The external impact threats may come from airborne missiles, aircraft impact, explosion blast and fragments. The impact effects of these threats on concrete and steel structures in a nuclear power plant are discussed. Methods and procedures for the impact assessment of nuclear power plants are introduced. Recent studies on penetration and perforation mechanics as well as progresses on dynamic properties of concrete-like materials are presented to increase the understanding of the impact effects on concrete containment structures.     

长江口北支STG剖面沉积特征分析

通过对长江口北支STG剖面沉积物粒度、环境磁学特征及有孔虫组合特征分析,发现该剖面沉积物以中粉砂和粗粉砂为主;磁性矿物以亚铁磁性矿物为主,不完整反铁磁性矿物含量较低;包含有3个有孔虫组合带。进一步分析,得出该剖面为潮滩沉积环境,并按自下而上顺序,可将其进一步划分出3个沉积层次,即层1→层3,层1为低潮滩沉积环境、层2为中潮滩沉积环境、层3为高潮滩沉积环境。反应潮流作用强弱的Epis-tominella naraensis与Ammonia convexidorsa含量百分比,自层1→层3依次变小,反映该剖面潮流作用自层1→层3依次减弱。