The effect of temperature on the corrosion of steel in concrete. Part 1: Simulated polarization resistance tests and model development

The effect of temperature on the corrosion rate of steel corrosion in concrete is investigated through simulated polarization resistance experiments. The simulated experiments are based on the numerical solution of the Laplace’s equation with predefined boundary conditions of the problem and have been designed to establish independent correlations among corrosion rate, temperature, kinetic parameters, concrete resistivity and limiting current density for a wide range of possible anode/cathode (A/C) distributions on the reinforcement. The results, which successfully capture the resistance and diffusion control mechanisms of corrosion as well as the effect of temperature on the kinetic parameters and concrete/pore solution properties, have been used to develop a closed-form regression model for the prediction of the corrosion rate of steel in concrete.     

Influence of conductivity on cathodic protection of reinforced alkali-activated slag mortar using the finite element method

Cathodic protection (CP) is considered to be the only rehabilitation method for chloride-induced rebar corrosion in reinforced concrete structures. The protection current distribution depends on several parameters, such as the geometry and number of rebars and the concrete resistivity. In order to investigate the influence of concrete resistivity on the possibilities and limitations of rebar protection, this paper presents a numerical approach based on the finite element method (FEM) in conjunction with laboratory results to determine its impact on the CP of alkali-activated slag mortar. An ordinary Portland cement was also tested for comparative purposes.     

Environmental factors affecting the corrosion behavior of reinforcing steel III. Measurement of pitting corrosion currents of steel in Ca(OH)2 solutions under natural corrosion conditions

Using a simple electrolytic cell, the pitting corrosion current of reinforcing steel is measured in Ca(OH)₂ solutions in presence of chloride and sulfate as aggressive ions. Pitting corrosion current starts to flow after an induction period which depends on the concentration of both the aggressive and the passivating anions. The pitting corrosion current densities reach steady-state values which depend also on the type and concentration of the corrosive and passivating anions. The corrosive action of the aggressive species decreased in the order: SO₄²⁻ > Cl⁻. Corrosion of the steel is found to be governed by a single electron transfer reaction. Raising the temperature decreases the induction period associated with pit initiation and increases the corrosion current associated with pit propagation. From Arrhenius plots, the activation energies for both pit initiation and pit propagation in presence of chloride and sulfate ions are calculated.     

地下洞室锚固结构的力学特性与锚固机理研究

将岩体、金属锚杆、砂浆胶结材料看作一种锚固岩体复合增强材料,通过能量等效的原理,建立岩体复合增强材料的层状模型,定量分析和研究锚固岩体的等效力学性质。在此基础上,针对地下洞室的扇形锚固结构,认为随着锚固深度的增加,锚杆的间距也随之增加,因此地下洞室锚固岩体的等效力学性质将随着锚杆间距的变化而变化,通过上述方法可以建立起地下洞室锚固岩体的等效力学参数与锚固深度之间的函数变化关系,并利用有限元方法计算了地下洞室锚固结构的等效性质,验证了理论分析的结果。上述问题的解决将对地下洞室的扇形锚固支护中的锚固机理有更清楚的认识。     

大岗山水电站右岸边坡开挖支护的有限元模拟

针对边坡开挖时可能对边坡稳定性产生的不利影响,基于锚固岩体弹塑性等效本构关系,以大岗山水电站右岸边坡为例,采用弹塑性有限元法对边坡开挖加固进行了数值模拟,分析了开挖边坡的稳定性,并对初拟的边挖边锚施工程序的合理性进行了评价,提出了若干对工程建设具有一定指导意义的建议.     

浅析尾矿库钢筋混凝土构件的安全检查

尾矿库排洪（排水）构筑物钢筋混凝土结构构件安全检查,是尾矿库安全检查工作的重要内容之一,本文就此问题进行了初步分析研究。     

Computational and experimental investigation of delamination in L-shaped laminated composite components

Formation of initial delaminations and growth of existing delaminations in L-shaped laminates made of plies of a unidirectional carbon fiber reinforced epoxy resin is investigated computationally and experimentally. For this purpose an experimental test is designed which allows to realize load states for which delamination is the dominant failure mechanism. Two types of test specimens, with and without initial delaminations, are investigated and good agreement is obtained between the computational predictions and the experimental results concerning delamination emergence, delamination growth, growth stability, the structural response, and the maximum principal strains.     

舞阳铁矿铁山庙、石门郭矿段地质特征研究

铁山庙、石门郭矿段为正生产铁山矿床的主要采区。由于矿床勘探程度较低,在开采过程中出现不少地质问题,通过近来补充勘查工作并结合开采生产资料,进一步综合研究,搞清了氧化矿石分布是受古侵蚀面制约的空间赋存规律,以及发现两矿段之间为地堑构构造关系等新认识,满足了设计与生产要求。     

玄武岩纤维混凝土的动态力学性能

采用Φ100 mm分离式霍普金森压杆 (SHPB) 试验装置研究了不同纤维体积掺量的玄武岩纤维混凝土在不同应变率下的冲击压缩力学性能 , 并对试验的有效性进行了分析。结果表明: 玄武岩纤维混凝土的动态强度增长因子与平均应变率的对数近似呈线性关系 , 强度与变形能力随平均应变率的提高而线性增加 , 体现了很强的应变率相关性 ; 纤维体积掺量为 0. 1 %的玄武岩纤维混凝土较素混凝土的动态抗压强度提高了 26 % , 变形能力提高了 14 %; 纤维体积掺量分别为 0. 2 %、 0. 3 %的玄武岩纤维混凝土的动态抗压强度比素混凝土高出 25 %左右 , 而变形能力较素混凝土无明显优势 ; 在玄武岩纤维混凝土的 SHPB试验中 , 试件破坏时刻为 123. 3～239.μ45 s , 近似恒应变率加载时间比例约为 62 % , 且应变率曲线的波动范围控制在 23 %左右 , 能够较好地满足应力均匀分布及恒应变率加载要求 , 表明 SHPB试验结果可靠。      

军用便携式加固计算机的电磁屏蔽设计

提出了军用便携式加固计算机的电磁屏蔽设计的解决方案,实践证明该方法能够有效地屏蔽各种电磁信号的干扰,保证设备正常工作。