泉城路改建工程

济南泉城路经改造建设 ,已经成为集交通、文化、商业、政务、旅游为一体的现代化综合商业街。道路由不足 2 0 m拓宽为 5 0 m,路面重新铺装 ,增加景观设计 ,同时对地上地下管线进行改造。     

德大铁路黄河特大桥主桥钢梁结构设计

德大铁路黄河特大桥主桥为1-(120+4×180+120)m下承式变高度连续钢桁梁,需要满足近期单线、远期双线的Ⅰ级铁路行车要求,具有跨度大、结构高的特点。首先介绍主桥的总体布置,而后对设计中采用的变高度"N"形主桁、正交异性整体钢桥面板、空间上平纵联、阻尼器、桥面柔性防水保护层、钢轨伸缩调节器、钢梁防腐涂装要求都作了详尽的说明。最后对钢梁的悬臂施工过程、70t固定式桅杆起重机进行介绍。     

基于Civil 3D的三维地质覆盖层建模技术及应用

Civil 3D作为一个面向岩土勘察行业BIM设计及应用的解决方案,已成为三维地质建模实现技术之一。针对水运工程勘区场地覆盖层不同工程地质特点,采用"点-面-体"三维地质模型的构建思路,分别提出单一和复杂覆盖层地质模型建模方法。结合某船闸工程案例,通过覆盖层边界线导入、曲面分割、曲面围合等技术,实现场地三维地质模型表层岩土体精细化表达,准确直观地展示了勘区覆盖层地质发育与分布情况。研究成果对于后续土方量计算、基坑开挖设计等岩土勘察BIM应用具有重要实践意义。     

TDCS/CTC系统路局中心网络防火墙桥接模式

TDCS/CTC系统作为铁路运输指挥的重要行车设备,系统网络安全是保障其正常运行的因素之一,防火墙是重要的网络安全设备。简单介绍防火墙在TDCS/CTC系统中应用情况及接入模式,并根据TDCS/CTC系统的特点详细分析中心网络的2种防火墙接入模式(路由模式和桥接模式)及透明桥接模式的优势。     

水上栈桥和平台在人造覆盖层中的优化设计

研究目的:通过分析人造覆盖层中入岩深度和不同边界条件下结构的整体稳定性,提供深水裸岩河床条件下人造覆盖层中水上栈桥和平台的优化设计方法,确保其安全性和可靠性。研究结论:(1)为减少爆破工作量,裸岩河床人造覆盖层中可以采用短桩形式,且短桩条件下采用"拉列琴假定"计算的入岩深度可以确保其安全性和可靠性;(2)因无法准确计算人造覆盖层对栈桥桩和平台桩的侧向抗力,桩的底部约束可按铰结和固结两种方式计算,实际情况介于这两者的计算结果之间;(3)若栈桥桩与平台桩在独立状态下不能满足安全性和可靠性,应增加二者之间的连接系,连接系的规格、数量和位置需通过整体强度及稳定性分析确定。     

干燥粉细砂层大断面斜井转入正洞施工技术

大西铁路客运专线干庆隧道3号斜井转入正洞施工中,成功运用了梯形断面弧形巷道垂直挑顶直接转入正洞的施工方案。就干燥粉细砂层地质,针对不同部位综合采取了密排超前小导管注改性水玻璃加固砂层施工技术、多台阶分部开挖法、侧壁超前旋喷咬合桩加固砂层施工方法、强刚度特殊结构门架技术和控制支护脚部下沉施工技术,分别阐述了其施工工艺流程和技术要点。该技术可对类似地质条件下的隧道施工和控制流砂、涌砂甚至砂层滑塌等现象提供指导和借鉴。     

Distribution of void fraction in bubbly flow through a horizontal channel: Bubbly boundary layer flow, 2nd report

A method of enveloping the hull with a sheet of microbubbles is discussed. It forms part of a study on means of reducing the skin friction acting on a ship's hull. In this report, a bubble traveling through a horizontal channel is regarded as a diffusive particle. Based on this assumption, an equation based on flow flux balance is derived for determining the void fraction in approximation. The equation thus derived is used for calculation, and the calculation results are compared with reported experimental data. The equation is further manipulated to make it compatible with a mixing length model that takes into account the presence of bubbles in the liquid stream. Among the factors contained in the equation thus derived, those affected by the presence of bubbles are the change of mixing length and the difference in the ratio of skin friction between cases with and without bubbles. These factors can be calculated using the mean void fraction in the boundary layer determined by the rate of air supply into the flow field. It is suggested that the ratio between boundary layer thickness and bubble diameter could constitute a significant parameter to replace the scale effect in estimating values applicable to actual ships from corresponding data obtained in model experiments.List of symbols a ₁ proportionality constant indicating directionality of turbulence - B law-of-the-wall constant - C _f local skin-friction coefficient in the presence of bubbles - C _f0 local skin-friction coefficient in the absence of bubbles - d _b bubble diameter (m) - g acceleration of gravity (m/s²) - j _g flow flux of gas phase accountable to buoyancy (m/s) - j _t flow flux of gas phase accountable to turbulence (m/s) - k ₄ constant relating reduction of liquid shear stress by bubble presence to decrease of force imparted to bubble by its displacement due to turbulence - l _b mixing length of gas phase (m) - l _m mixing length of liquid phase (m) - l _mb diminution of liquid phase mixing length by bubble presence (m) - Q _G rate of air supply to liquid stream (l/min) - q _/g velocity of bubble rise (m/s) - 2R height of horizontal channel (m) - T _* integral time scale (s) - U _m mean stream velocity in channel (m/s) - U friction velocity in channel (m/s) - V volume of a bubble (m³) - u, ¯ v time-averaged stream velocities inx- andy-directions, respectively (m/s) - u, v turbulent velocity components inx- andy-directions, respectively (m/s) - v root mean square of turbulence component in they-direction (m/s) - root mean square of bubble displacement iny-direction with reference to turbulent liquid phase velocity (m) - y displacement from ceiling (m) - local void fraction - _m mean void fraction in boundary layer - _m constant relating local void fraction to law-of-the-wall constant - _t reduction of turbulent stress (N/m²) - law-of-the-wall constant in turbulent liquid region in absence of bubbles - ₁ law-of-the-wall constant in turbulent liquid region in presence of bubbles - ₂ law-of-the-wall constant in gas phase - _m constant indicating representative turbulence scale (m) - viscosity (Pa × s) - v kinematic viscosity (m²/s) - density (kg/m³) Suffixes G gas - L liquid - 0 absence of bubbles     

新型酸性水玻璃注浆材料的研究与应用

针对城市地铁穿越砂层时注浆预加固的材料问题,研究磷酸-水玻璃注浆材料的凝胶时间、凝胶形态和砂土固结体强度的影响因素以及工程应用材料配比,设计磷酸-水玻璃注浆材料室内凝胶性能试验和砂土固结体强度试验,并与传统的硫酸-水玻璃注浆材料进行系统性对比,最后根据室内试验选择合适的材料配比进行现场注浆试验。试验结果表明:1)磷酸-水玻璃混合液中,当磷酸的掺量增大时,磷酸与水玻璃的体积比增大,混合液的pH值减小,凝胶时间增大,存在一一对应的关系;2)磷酸-水玻璃混合液的pH值是磷酸-水玻璃浆液凝胶时间和凝胶形态的决定性因素;3)磷酸-水玻璃浆液中磷酸质量分数、水玻璃波美度和混合液体积比分别变化时,加固体抗压强度稍有变化,影响较小。     

湍流激励下简支平板振动特性的解析法研究

解析法基于随机激励理论,采用湍流脉动压力的Corcos模型作为输入,结合考虑流固耦合时平板的频响函数,求解得到平板振动速度的自功率谱密度。计算结果同已有文献吻合较好,证明了解析法的正确性。同时研究结果表明：湍流激励下平板的振动特性体现了平板本身的固有特性;随着来流速度的增大,平板振速的均方谱密度幅值按一定的数值关系增大。     

动车组高压线缆屏蔽层接地分析

高压屏蔽电缆在动车组电气系统的运行过程中会产生感应电压,需要通过屏蔽层的合理接地来保证车辆运用安全和减少线缆对外电磁辐射。介绍了动车组的接地系统,以变压器次边绕组电缆为例,从屏蔽层感应电压的产生机理出发,分析了高压线缆屏蔽层单端接地的原理,提出了线缆屏蔽层的接地结构,并通过试验对比了屏蔽层在可靠接地和接地不良条件下的感应电压值,验证了接地结构的可靠性。