高压注浆技术在处理桩基工程中Ⅲ类、Ⅳ类桩的应用

由于地质情况和施工原因造成的预应力管桩基础出现的Ⅲ类、Ⅳ类桩的实际情况,综合考虑了多方面的因素后采用了注浆技术对Ⅲ类、Ⅳ类桩进行了处理使其桩身完整性达到Ⅰ类、Ⅱ类桩的要求。结合工程实例,就该注浆技术方案的设计及其注浆施工工艺,并对注浆效果进行的检测及评价。对类似工程的Ⅲ类、Ⅳ类桩处理进行了简要的阐述,起一定的借鉴作用。     

Research on pavement longitudinal crack propagation under non-uniform vehicle loading

The top-down crack (TDC) has become the major cracking mechanism in thick pavement structure, especially for the perpetual pavement. The heavy-vehicle load condition plays a key role in the fracture characteristics of pavement cracks. A three-dimensional finite element (FE) model of the tire tread rubber-block and the pavement is established to describe the stress–strain field of the pavement with TDC. The three-directional friction condition and non-uniform distribution between tire and pavement are especially considered. Then the orthogonal Design of Experiment method is applied to discuss the effect law of fracture characteristics for the longitudinal crack affected by the multiple loading parameters simultaneously. Based on the statistics and data analysis of the diverse test results, it is found there is a nonlinear relationship between the equivalent stress intensity factor of the pavement and the load parameters.The longitudinal distance (from the load location to the center of the crack port) has a great influence on the equivalent stress intensity factor. The equivalent stress intensity factor of the crack port is more than double the crack tip buried in pavement, which extends in II/III composite type mostly. The simulation results can be used as reference for the further study on the fracture mechanism of pavement cracks and their control technique.     

Analysis of Overheating Rupture in Heat-Transfer Tubes Causing Corrosive High-Temperature Reaction

In the steam generator of a liquid metal fast breeder reactor, a defect penetrating through heat-transfer tube will cause high-pressure water/steam to spout into the low-pressure sodium filling the space outside the tube, to initiate sodium-water reactions. If the leak exceeds an intermediate level (~2kg/s), the reaction jet may rupture adjoining tubes with overheating in the event of insufficient cooling available inside the tubes. Such phenomenon of overheating tube rupture presents a serious problem to the economy and safety of steam generator. With a view to clarifying the failure behavior of steam generator heat-transfer tubes under such condition a model of the phenomenon is derived through a series of tests on sodium-water reactions making use of a test loop representing the scale model of an actual fast breeder steam generator. Comparison of actual test data with analysis based on the model has yielded the following information: The failure behavior of gas-pressurized tubes fall into two categories: (a) by creep failure—occurring upon increase of cumulative damage with tube wall wastage caused by the reaction jet and (b) by ductile failure accompanied by creep—upon tube heating with the reaction jet to the extent of lowering tube wall strength below the hoop stress exerted by tube pressure. Analysis of the two categories of failure results in estimation of the percentage difference between analyzed and measured times to failure of 35–50% in the case of creep failure and of 20–50% in the case of ductile failure accompanied by creep. In practical application to steam generators in order to provide a safety margin a time factor—i.e., the safety factor indicating multiple of actual time to failure—of 3 is adopted against 1.5–2 indicated from test to be the actually applicable value.     

桂东南客家民居的类型与特点

桂东南是广西最主要的客家聚居区，相应的客家民居类型可分为基本类型、发展类型、变异类型和相关类型四大类，其中基本类型有堂屋和横屋，发展类型有堂横屋、围龙屋、围楼、围堡和围村，变异类型有传统变异和洋式变异，相关类型有祠堂和碉楼，各种类型之间存在或强或弱的关联，并共同塑造了桂东南客家民居的围合性、对称性、向心性、秩序性和匀质性等特点。     

配抄中、低档文化印刷纸的废纸脱墨浆生产线改造

介绍南纸公司300t／d废纸脱墨浆（DIP）生产线改造成能配抄中、低档文化印刷纸所增加的设备及功能，改造后设备的运行状况及生产工艺的调整。     

注射模滑块的结构类型与设计

针对注射模中滑块结构的广泛应用,详细介绍了注射模滑块的各种结构类型与设计要点。     

钢筋套筒灌浆连接研究进展

钢筋套筒灌浆连接是当前预制混凝土结构钢筋连接的主要方式。从材料、界面、连接的角度，针对其国内外相关研究成果开展系统分析与总结。结果表明：套筒可为金属、非金属材质(如FRP),锥形套筒的连接性能优于圆柱形的，套筒长度不应短于临界长度，内径越小越有利，壁厚不应小于被连接钢筋直径的1/13,但也不宜过厚；低温、负温灌浆料适用的环境温度分别不超过-5、-10℃,耐高温灌浆料可通过掺入聚丙烯纤维进行制备；灌浆料与钢筋界面的黏结强度主要与灌浆料抗压强度的平方根相关，并受到套筒约束能力、高温作用的显著影响；钢筋套筒灌浆连接受拉失效模式包括套筒外钢筋断裂、灌浆料与钢筋界面黏结失效以及套筒与灌浆料界面黏结失效；荷载类型对钢筋套筒灌浆连接力学性能的影响较小，失效模式转变的关键温度是400℃,灌浆缺陷率不超过20%能确保连接接头的可靠性；界面、钢筋黏结长度对钢筋套筒灌浆连接力学性能的影响显著。基于此，提出全黏结长度和双界面两个概念，以控制钢筋套筒灌浆连接的承载性能与失效模式。同时，提出有待开展的研究：灌浆料的本构关系、率敏感性、热工参数等；受高温作用、侧向约束的影响，灌浆料与钢筋界面的黏结应力-滑移本构关系...     

平衡式管线旋塞阀开发设计

介绍了平衡式油密封管线旋塞阀的工作原理和主要特点,论述了阀门性能及要求。     

地铁火灾自动报警系统工程应用问题及对策

在投入运行的地铁项目中尽管按照现行的标准规范设置了火灾自动报警系统．但在系统设备选型、现场设备设置及电气火灾监测预防等方面尚存在一定问题．通过对现场出现的问题进行调研分析，并结合工程实践经验提出相应的解决对策。     

Selection of injection conditions for aluminum particles as a raw material by numerical analysis in the synthesis of ultrafine particles with transferred type arc plasma

We investigated by numerical analysis the dependence of vaporization behavior of aluminum particles injected into transferred type arc plasma on injection conditions in synthesis of aluminum nitride ultra fine particles. On the basis of calculation results, we chose one proper injection condition where aluminum particles vaporized more. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(2): 46–52, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20852