印尼地区嵌岩灌注桩竖向承载特性现场试验

为更加深入研究不同竖向荷载作用下大直径嵌岩灌注桩的承载特性与荷载传递规律,以印尼地区某工程为依托,对3根直径为800 mm的嵌岩灌注桩进行单桩竖向抗压静载试验与桩身应力测试。试验结果表明:3根试桩的Q-s曲线均为缓变型,沉降量均不超过17 mm,回弹率较大,介于54.8%~70.9%之间,残余沉降较小,承载力较高,均满足设计要求。桩身轴力随桩顶荷载的增加逐渐增大,随深度逐渐递减;桩侧摩阻力的发挥具有异步性,随着荷载的增大,桩侧摩阻力逐渐发挥,在嵌岩段桩侧摩阻力最大,但仍未充分发挥;桩端阻力随桩顶荷载的增加近似呈线性增大,在最大荷载作用下,桩端阻力占比约55%,表现出摩擦端承桩的特性。研究结果对国内桩基规范的完善以及当地桩基规范的制订具有较重要的意义。     

基于实测的基坑降水对周边土体承载能力的影响研究

工程实践证明,基坑安全与基坑降水密切相关,为摸清基坑降水与基坑安全间的关联关系,进行了大量的原位测试工作,以大量的同步地下水位监测、承压板载荷试验、静力触探试验数据为基础,借助计算机,构建起了无截水措施情况下基坑降水后基坑周边地下水位变化和土体承载能力变化的经验数学模型。介绍了模型的构建过程和应用效果。     

利用无棱镜电子全站仪进行网架结构空中拼装定位

网架结构的空中拼装是网架工程施工中的一个关键技术环节,为确保网架结构施工的高质量和高安全度,在实践的基础上提出了利用无棱镜电子全站仪进行网架结构空中拼装定位的思路,给出了利用无棱镜电子全站仪进行网架结构空中拼装定位的操作要领和基本技术要求,介绍了利用无棱镜电子全站仪进行网架结构空中拼装定位的技术关键,在网架结构空中拼装的高精度与高效率问题上进行了有益的探索。     

盐穴储气库卤水介质对A3钢腐蚀规律研究及防护分析

为了解决地下盐穴储气库注采管线与造腔管线合并带来的造腔期的卤水腐蚀问题,采用水腐蚀性测试方法,研究了地下盐穴储气库卤水管道工况和介质对管道腐蚀的影响规律。研究结果表明,温度、卤水浓度、溶解氧含量、流速均会加剧卤水对A3钢的腐蚀,结合卤水管道应用工况,建议选用双金属复合钢管,既能起到优良的耐蚀防护作用,又能在一定程度上降低成本,对实际工业生产具有较高的经济价值。     

STUDY ON THE FALLING FILM ABSORPTION OUTSIDE SMOOTH AND ENHANCED TUBES

1. INTRODUCTION The absorber-heat exchanger in any absorption system is an important component and its characteristics have significant effects on the overall system performance, size and first cost. The heat transfer surface of an absorber might account for up to 40% of the total heat transfer surface in an absorption machine[1]. Consequently, the complex heat and mass transfer phenomena occurring in the absorber have been the subject of a great amount of research, especially in the last …     

Some significant environmental issues in high-rise residential building design in urban areas

Almost in all the major cities in Asian countries, residential buildings are characterized with high-rise and high density. Under this circumstance, achieving comfortable and healthy indoor environment with minimized energy consumption becomes a very challenging engineering and societal issue. While the wide use of air-conditioning helped to improve thermal comfort, health problems associated with poor indoor air qualities have appeared more frequently. The increased energy consumption is also a great concern in view of its impact on the energy economics of the region. Drawn from some of the onsite measurements and survey, and also the author’s personal observation, some of the key issues are discussed in this paper.     

Seismic performance of repaired hollow-bridge piers

To develop an effective repair technique for rapid bridge restoration after an earthquake, four hollow bridge columns were cyclically loaded to failure, repaired and retested. The repair process includes using dog-bone shape bars to replace the fractured longitudinal bars in plastic hinges and using FRP (Fiber Reinforced Plastic) wraps to enhance the deformation capacity of columns. The repair aims to restore seismic capacity in terms of strength and ductility. Test results indicate that the fractured longitudinal bars can be completely repaired and the deformation capacities of the columns were enhanced by FRP wraps. However, due to concrete deterioration and the buckling of the longitudinal bars in the inner layer of the hollow sections, the test results also indicate the repaired column strengths are less than anticipated.     

基于花岗岩卸荷试验的损伤变形特征及其强度准则

 对取自大渡河大岗山水电站的花岗岩开展高应力下2种卸荷方案的力学特性试验,并与同围压下的常规三轴压缩试验结果进行对比分析,研究岩石卸荷过程中的破坏机制、力学强度参数损伤劣化效应及其卸荷破坏的强度特性。研究结果表明：(1) 岩石卸荷过程中向卸荷方向回弹变形强烈、扩容显著,脆性破坏特征明显。(2) 卸荷试验中,开始卸荷点处的变形模量较常规三轴压缩试验已发生一定的损伤劣化,其损伤因子与初始围压近似成线性关系,而该点处的泊松比所表现出的损伤劣化效应却不明显。(3) 卸荷过程中,泊松比随着围压的不断卸除,呈现指数关系增长;变形模量变化平缓,但在岩样卸荷屈服破坏点处陡降。(4) 在高应力卸荷条件下,Mogi-Coulomb强度准则能很好地反映其破坏强度特性。(5) 相比较于常规三轴压缩试验,卸荷时的抗剪强度参数c值减小而j 值增大,其变化量与卸荷方式有关。这些结论揭示高应力条件下花岗岩的卸荷力学特性,为西部水利水电工程的开挖、支护设计及其稳定性分析提供了理论参考。     

利用废橡胶提高冶金焦化产物质量的研究

利用2kg热解装置模拟冶金工业高温焦化工艺,对煤配加废橡胶共炼焦产物特性进行研究.结果表明,共炼焦可改善煤气组成,增加H2、CH4含量,至少提高煤气热值23%,提高煤焦油收率和质量,并且废橡胶颗粒度明显影响焦炭质量.与原煤单独炼焦焦炭相比,在煤中配加1%、颗粒度为φ＜0.20 mm的废橡胶共焦化时,焦炭抗碎强度M20提高3.6%、反应后强度提高4.2%、反应性降低3.5%、硫含量不增加、降低灰分和氮含量;煤气中硫化氢浓度增加约30%.废橡胶配煤炼焦虽使硫化氢浓度有所增加,但可提高焦化产品质量.     

Microstructure and properties of epitaxial layers by laser glazing

Various processes of laser surface melting are employed to modify the features of epitaxially grown microstructures in the melt. Three kinds of microstructures are demonstrated in this investigation. The one with complex microstructures possesses the best resistivity against hot stress corrosion.