基于温度变化的PCCP管道环境腐蚀性监测研究

为了准确评估大伙房输水(二期)工程中预应力钢筒混凝土管(PCCP)的环境腐蚀动态,探究工程环境腐蚀动态监测的必要性,本研究采用ECI智能监测装置对埋地管道进行了系统的环境腐蚀性动态试验,并简述了ECI设备的系统组件和安装结构。研究表明,环境温度的升高会导致PCCP管道的腐蚀活性增强,这一发现为工程实施环境腐蚀动态监测的必要性提供了科学依据。本试验和大伙房输水工程环境腐蚀动态监测的成功,可为面临类似环境腐蚀问题的管输工程提供实用参考。

某渠道土层对钢铁结构腐蚀性试验研究

通过大量的土对钢铁结构腐蚀性试验研究成果,准确判断,给工程设计提供了合理的参数。该工程通水4年运行良好。

水泥加固腐蚀性土强度特征研究进展

中国幅员辽阔,具有大面积的盐碱地、有机质土,地下咸水区也分布较广。且随环境的恶化及中国近代工业化的推进,除去天然腐蚀性土外越来越多的土地受到污染变为腐蚀性土。对腐蚀性土进行改性处理及达到二次利用的目的,多采用硅酸盐水泥对其进行固化。水泥加固腐蚀性土多用于其原腐蚀环境中,易使加固体发生劣化,强度衰减情况较为显著。对不同性质的腐蚀性土进行分类并对其研究进展进行归纳总结,对水泥加固腐蚀性土强度变化机理进行论述,总结影响水泥加固腐蚀性土强度变化的因素。对有关水泥加固腐蚀性土强度特征问题研究不足之处进行讨论,为水泥土加固腐蚀性土未来研究方向提出展望。

某盐湖地区土的腐蚀性评价

盐湖地区钾、钠、镁、锂、气资源丰富,盐湖资源的综合开发利用越来越受到人们的重视。但盐湖地区土环境中Mg^(2+)、Cl^-、SO_4^(2-)离子含量高,对混凝土和钢结构的侵蚀破坏非常严重。通过化学和电化学检测手段,分析了盐湖地区几个典型地点土的电阻率、含盐量、pH值、氯离子含量和硫酸根离子含量等理化指标,根据相关标准分析评价了盐湖地区土的腐蚀性,评价结果表明,该盐湖土属于强腐蚀土。

三洲南泵站重建工程混凝土灌注桩施工

佛山市高明区三洲南泵站重建工程泵房的大体积底板,泵房肘形流道和电机层梁,压力涵和自排涵的箱涵,防洪闸、自排闸和清污机闸闸室的底板和墩墙等的地基基岩,可能会产生流土或过渡型渗透变形。在充分考虑不良地质条件的前提下,本工程采用直径1 000 mm混凝土灌注基础桩,实桩总长121.19 m进行软基础地基处理,对同类工程的地基处理有一定借鉴作用。

榆次区地下水源置换供水工程地质问题分析

为实施关井压采,节约区域用水、遏制地下水超采、提升水源涵养能力、加快榆次区榆太祁中型孔隙地下水超采区地下水位回升,推动区域经济转型发展。新建榆次区地下水超采区水源置换工程,工程利用正阳污水厂中水水源,置换农业灌溉地下水。文章对供水管线存在的环境水腐蚀性、土的腐蚀性、基坑涌水、黄土湿陷性等工程地质问题进行了分析,并在评价供水工程地质基础上,提出了相应的工程措施。

沙湾县某小区岩土工程勘察分析

沙湾县某小区拟建多座多层和高层住宅楼建筑,分别为砖混结构和框剪结构。根据场地的地形地貌、地层岩性及物理力学性质、地下水的埋藏条件、土的腐蚀性等勘察结果,对场地稳定性、场地地震效应、场地冻胀性进行了评价,从场地地震效应可判定场地土类型为中硬场地土,场地类别为Ⅱ类,属可进行建设的良好场地。不存在液化问题。第二层圆砾可作为建筑地基持力层和良好下卧层。建议采用天然地基,多层建筑基础类型采用条形基础、矩形基础。

建筑物基础混凝土防腐技术措施探讨

建筑物基础混凝土防腐在工程施工中遇到较多而且必须进行人工处理的一项非常重要的工作。主要探讨坐落于氯盐超标的腐蚀环境中建筑物基础氯盐防腐处理技术措施及方法,以保证施工质量与建筑物的安全性和耐久性。

潍坊寒亭区盐渍土研究及工程对策

通过潍坊寒亭区第二净水厂工程勘察,对盐渍土的溶陷、盐胀及腐蚀性进行了研究,提出了拟建工程的处理对策,为潍坊寒亭区后续工程积累资料,亦为今后类似工程问题的治理提供可借鉴的经验。

新疆石油管线沿线土的腐蚀性测试与评价

针对新疆干旱地区土质的特点,在不能进行原位和原状土的腐蚀性测试的条件下,介绍了采用处理后的扰动土进行干湿比较试验和用化学分析方法,最终取得沿线土的腐蚀性测试与评价结果,以及工作中的体会。

新疆某供水工程勘察对盐渍土特性分析与评价

根据新疆某供水工程勘察实例,对本地区盐渍土成因、空间分布及特点进行综合分析与评价,并提出几种适用于该地区盐渍土的地基处理方案及施工中的注意事项。

乌苏市克孜加尔二库防腐设计

乌苏市克孜加尔二库地下水坝基土体对混凝土结构具有腐蚀性,对钢结构具中等腐蚀性,对钢筋混凝土结构中的钢筋具弱腐蚀性。在工程设计中采用涂刷一层5 mm厚的PVC油膏及抗硫酸盐水泥防腐,取得了较好的应用效果。

汕尾市区供水改造工程水文地质条件分析

为解决以公平水库为水源地、通过新建取水口及加压泵站、输水管道等新建供水工程的水工环地质问题。文章在分析工程规模、流经地域、地下水贮藏、地质概况等的基础上,对环境水腐蚀性、土对钢结构的腐蚀性进行了评价,对场地类别及地震效应、砂土渗透变形判别、主要岩土层物理力学指标建议值等岩土力学性能进行了分析,提出了各岩土层开挖边坡参数值,为工程实施提供了科学支撑。

Influence of heat treatment on corrosion behavior of hot rolled Mg5Gd alloys

The influence of heat treatment on the corrosion behavior of rolled Mg5 Gd alloys in 3.5 wt.% Na Cl solution saturated with Mg(OH)2 was characterized by immersion test, electrochemical test, scanning electrochemical microscopy(SECM) and corrosion morphology analysis in order to improve the corrosion resistance of Mg alloys. The results showed that solution treatment reduced the corrosion rate of the Mg5 Gd significantly, resulting in relatively uniform corrosion and shallow corrosion cavities due to the dissolution of Cd-containing particles. The following aging process could further decrease the corrosion rate. Precipitation of nano-sized Cd-containing particles did not cause apparent micro-galvanic corrosion, which could be attributed to the formation of a protective corrosion product film fully covering the particles.

Spatial Distribution of Soil Erosion Sensitivity on the Tibet Plateau

The Tibet Plateau, occupying the main part of Qinghai-Tibet Plateau and having an average altitude of 4 500 m, has geomorphological features that are unique in the world, with soil erosion being one of the main ecological problems. Thus the main objectives of the present research were to set up an efficient and simple way of evaluating spatial distribution of soil erosion sensitivity in the Tibet Plateau as well as the responses of soil erosion to changes of natural environmental conditions, and to indicate key regions where soil erosion should be preferentially controlled. Based on the Universal Soil Loss Equation (USLE), the study applied geographic information system (GIS) technology to develop a methodological reference framework, from which soil erosion sensitivity could be evaluated. The impact of precipitation, soil, topography and vegetation on soil erosion was divided into classes of extreme sensitivity, high sensitivity, medium sensitivity, low sensitivity and no sensitivity. With the aid of GIS, the resultant map from overlaying various factors showed that soil erosion sensitivity had great discrepancy in different parts of the region. In the southeastern part of the Tibet Plateau there were mainly three classes of sensitivity, namely, extreme, high and medium sensitivity. However, the other two classes, low and no sensitivity, were dominant in the northwestern part.

Microstructure and corrosion behavior of as-cast ADC12 alloy with rare earth Yb addition and hot extrusion

The effects of rare earth ytterbium(Yb)addition and hot extrusion on the microstructure and corrosion behavior of as-cast ADC12 were studied by optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD).The experimental results demonstrate that both the Si phase andβ-Al5FeSi phase in the alloy with 0.9 wt%Yb have been remarkably refined,and the Al3Yb intermetallic compound has also been obtained.The Si,β-Al5FeSi,and rare earth phases are further refined in the alloy at 0.9 wt%Yb and hot extrusion.The results of the immersion corrosion tests and electrochemical experiments show that the corrosion current density(8.56μA/cm2)of the alloy with 0.9 wt%Yb addition and hot extrusion is 50.6%lower than the untreated alloy(17.33μA/cm2),and the polarization resistance(9252Ω·cm2)was 71.3%higher than the untreated alloy(2654Ω·cm2).The corrosion in the cathode phase in the micro-battery was refined to varying degrees attributable to the addition of Yb and hot extrusion,where the cathode reaction in the corrosion process caused a decrease of the corrosion rate.

Effect of Gd on microstructure, mechanical properties, and corrosion behavior of as-homogenized Mg-8Li-3Al-2Zn-0.2Zr alloy

The microstructure observation,tensile test,electrochemical measurement,and corrosion morphology characterization were conducted to study the effect of Gd on the microstructure,mechanical properties,and corrosion behavior of as-homogenized Mg−8Li−3Al−2Zn−0.2Zr(LAZ832−0.2Zr)alloy.The addition of trace Gd can improve the mechanical properties of as-homogenized LAZ832−0.2Zr alloy by refining the microstructure,reducing the content of AlLi softening phase,and forming Al_(2)Gd strengthening phase.Meanwhile,the addition of trace Gd can weaken the microgalvanic corrosion between matrix phase and AlLi phase,inhibit the galvanic corrosion betweenα-Mg phase andβ-Li phase,and result in the formation of dense oxide film containing Gd_(2)O_(3),thereby improving the corrosion resistance of the alloy.When the Gd content is 1.0 wt.%,the alloy shows the best comprehensive properties with the ultimate tensile strength of 189.8 MPa,elongation of 42.3%,and corrosion rate(determined by hydrogen evolution)of 0.86 mm·a^(−1).

Corrosion leaking of preheater weldment in alumina factories

Stress corrosion cracking (SCC) and anticorrosion measures of TU42C weld-joint were studied by constant load experiments and pickling experiments. The results show that in 40%(mass fraction) NaOH solution at 110℃, caustic SCC occurs in TU42C weld-joints at the applied potential of-1020mV(vs SCE) for 3d while at the potential of-950mV(vs SCE) for 10d. All the cracks are intergranular. In the 10% sulfuric acid, the cracks have the most negative self-corrosion potential-432.5mV(vs SCE) and are active to be further corroded by the acid. Because of the same corrosion behaviour as the lab weldment, preheater’s cracking in alumina factories is attributed to the combining actions of previous caustic SCC in Bayer solutions and continuous acid corrosion by pickling with the addition of RD. The following measures are effective to prevent the corrosion failure of preheater, such as postweld heat treatment at 620℃ to relax the residual weld stress, addition of CC3 and L826 as the corrosion inhibitors to improve the pickling and cleaning by the high pressure water instead of by pickling.

Bending performance of TRC-strengthened RC beams with secondary load under chloride erosion

Textile reinforced concrete(TRC)has good bearing capacity,crack resistance and corrosion resistance and it is suitable for repairing and reinforcing concrete structures in harsh marine environments.The four-point bending method was used to analyze the influence of the salt concentration,the damage degree and the coupled effect of the environment and load on the bending performance of TRC-strengthened beams with a secondary load.The results showed that as the salt concentration increased,the crack width and mid-span deflection of the beam quickly increased,and its bearing capacity decreased.As the damage degree increased,the early-stage crack development and mid-span deflection of the beam were less affected and the ultimate bearing capacity significantly decreased.In addition,the coupled effect of the environment and load on the beams with a secondary load was significant.As the sustained load increased,the ultimate bearing capacity of the strengthened beam decreased,and cracks developed faster in the later stage.In addition,the mid-span deflection of the beam decreased at the same load level because of the influence of the initial deflection due to the sustained load corrosion.

Evaluation of Subsoil Corrosivity Condition around Baracaia Area Using the Electrical Resistivity Method--A Case Study from the Muglad Basin, Southwestern Sudan

This paper evaluate subsoil corrosivity using the electrical resistivity method which was carried out to determine the subsoil resistivity and estimate the degree of corrosion, the resistivity measurements were conducted by using SAS300c resistivity meter. This involves applying a voltage into the soil through metal electrode and measuring the resistance to the flow of electric current. An AC-power supplies current flow （I） between two outer electrodes and the resultant voltage different （V） between two inner electrodes is measured using the Wenner Arrangement. The soil resistance given by R = V/I. This needs to be standardized over a unit length, the resistivity p which measured in ohm-m the equation is, ρ= 2ДdR. There are many factors control the ground resistivity such as soil composition, moisture content, pore water chemistry and pH. The results of the survey show inverse proportion between corrosivity and electrical resistivity, therefore resistivity method is very useful to incipient the corrosion as well as effective, quick, reliable and economic method. Structures such as natural gas, crude oil pipelines and steel constructions were reported to have been affected by soil corrosion all around the world, it can be concluded that sub soil corrosivity around the study area increases southwestern ward with depth.