Medium-size triaxial apparatus for unsaturated granular subbase course materials

This paper proposes a testing method for evaluating the effect of water content on the deformation–strength characteristics of unsaturated subbase course materials. A medium-size triaxial apparatus for unsaturated soils is newly developed in order to examine the mechanical behavior of unsaturated subbase course materials subjected to fluctuations in water content and to shorten the testing time. It adopts the pressure membrane method with hydrophilic microporous membrane filters, instead of the pressure plate method with ceramic disks, and controls both pore air pressure and pore water pressure at the cap and the pedestal separately. The results of the proposed testing method, carried out by this apparatus, are shown to conform well to the results of previous researches. This indicates that the medium-size triaxial apparatus for unsaturated soils is highly useful for triaxial compression tests and water retentivity tests on unsaturated granular base course materials and for shortening the total testing time.     

Q420B钢的低温环境焊接性工艺试验

通过斜Y坡口抗裂性试验和接头各项力学性能试验,研究420B钢的裂纹敏感性,采用低氢焊接方法和焊接材料,保持焊接过程低氢条件及焊后保温缓冷。可以通过低温预热进行焊接,为焊接工艺文件提供依据和指导。     

向家坝800MW发电机过励限制器的剖析及试验

分析了过励限制器的功能特点和设计要求,提出了向家坝水电站800MW发电机过励限制器模型。通过RTDS仿真试验和动态数据分析,总结了过励限制器与过励保护、强励限制和发电机过负荷保护配合的技术特点,对大容量发电机组过励限制器应用提供了借鉴和参考。     

大型水轮发电机通风模拟试验台新型测控系统设计与实现

针对大型水轮发电机通风模拟试验要求,设计并提供了一种基于远程控制技术、虚拟仪器技术、PXI技术的先进的、功能完善的测控系统,并在文中论述了该测控系统的设计方案及其实现方法。该测控系统实现了大型水轮发电机通风模拟试验的自动控制与测量,试验结果表明,该系统具有测量与控制精度高、实时性、稳定性高以及抗干扰能力强等优点。     

Bearing behavior and failure mechanism of squeezed branch piles

The current practice for the design of squeezed branch piles is mainly based on the calculated bearing capacity of circular piles. Insufficient considerations of the load-transfer mechanism, branch effect and failure mechanism, as well as overreliance on pile load tests, have led to conservative designs and limited application. This study performs full-scale field load tests on instrumented squeezed branch piles and shows that the shaft force curves have obvious drop steps at the branch position, indicating that the branches can effectively share the pile top load. The effects of branch position, spacing, number and diameter on the pile bearing capacity are analyzed numerically. The numerical results indicate that the squeezed branch piles have two types of failure mechanisms, i.e. individual branch failure mechanism and cylindrical failure mechanism. Further research should focus on the development of the calculation method to determine the bearing capacities of squeezed branch piles considering these two failure mechanisms.     

高速公路试验检测管理

该文针对目前高速公路工程试验检测管理工程的现状进行分析,然后以某高速公路工程为例,详细分析如何做好高速公路工程试验检测管理工作。     

子结构拟动力试验的CD-Wilson θ法研究

子结构拟动力试验中的组合数值积分方法具有显式数值积分方法无需迭代和隐式数值积分方法无条件稳定的优点。为解决CD-Newmark方法存在上限频率取值较大导致时间步长变小的问题,将显式的中心差分法和隐式的Wilson-θ法进行组合,形成CD-Wilson θ法。经计算和对Wilson-θ法做出一定修正后,得出该组合数值积分方法的稳定性和精度条件。通过Matlab软件编程,提出了CD-Wilson θ法稳定性的参数取值范围,并用算例做出对比验证。结果表明这种组合数值积分方法不仅稳定性和精度性好,而且比CD-Newmark法的时间步长范围更大。     

廊坊市南水北调配套水厂以上输水管道工程土工试验指标分析

本文主要阐述了廊坊市南水北调配套水厂以上输水管道工程土工试验指标,并对其进行了详细地分析。     

福建地区花岗岩风化体渗透系数研究

以福建华东船厂修造船项目帷幕灌浆检测试验为工程依托,对比分析钻孔注水原位试验、室内土工试验、以及经验公式取得的渗透系数,通过研究粗细粒土的含量对渗透系数的影响,提出适用于初期判断渗透系数的快速经验公式,能较好地应用于福建地区花岗岩风化体,并得到相关工程的验证。     

插盘式脚手架试验研究及受力分析

为研究插盘式脚手架的力学性能,进行了节点单向、双向拉伸及单向压缩试验,得到其破坏模式及荷载-位移曲线;现场对单跨两步脚手架体系进行堆载试验,得到各杆件应力.建立三维杆系有限元计算模型,模拟脚手架体系堆载试验,采用弹簧单元模拟插盘式节点,轴向线刚度取节点试验值,通过改变弹簧单元的切向刚度和转角刚度对整个结构进行参数分析,得到与试验结果较吻合的数值分析模型,并与节点铰接的模拟结果进行对比.分析表明:插盘式节点采用弹簧单元可以更好地模拟结构的受力状态,需要考虑弹簧的轴向刚度和切向刚度,但可以忽略转角刚度.