西南某机场水泥混凝土道面板应力计算分析

为了对西南某机场水泥混凝土道面板进行应力分析,通过现场钻芯取样和劈裂实验得出劈裂强度值和基层顶面反应模量。应用ANSYS软件建立三维有限元模型,计算不同飞机荷载作用下的板边应力。由应力折减系数得出板边计算应力,判断道面能够运行的最大飞机重量。比较板边自由与不自由两种状态下道面产生的应力和位移,发现高温作用下道面的受力变化与低温状态下不同,对机场道面在夏季和冬季运行时提出建议。     

某磁浮大跨斜拉桥竖向刚度限值研究

以某磁浮轨道交通(40+80+228+228+80+40)m大跨钢箱梁斜拉桥为研究对象,采用有限元软件ANSYS和多体动力学软件UM分别建立桥梁和磁浮列车模型。基于车桥耦合振动方法,针对2列磁浮列车相向行驶并在主跨跨中交会的最不利情形,进行列车以不同速度通过桥梁时不同梁高下车桥系统的动力响应及磁浮大跨桥梁的竖向刚度限值研究。结果表明:磁浮列车的竖向动力响应随车速的增大而显著增大,时速从40 km增大到140 km时,列车竖向动力响应增幅达到120%以上;车体竖向加速度和Sperling指标不是桥梁结构刚度限值的控制因素;磁浮列车的悬浮间隙对梁体刚度变化较为敏感,随着梁体刚度逐步增大,悬浮间隙的波动变小,梁体挠跨比减小约25%,悬浮间隙波动减小幅度达35%,悬浮间隙可作为中低速磁浮大跨桥梁结构刚度限值的控制指标;梁体挠跨比1/3015可作为磁浮大跨桥梁的竖向刚度限值。     

Centrifuge modelling of pipe-soil interaction in clay with crust layer

Seabed in regions, such as the Gulf of Guinea and North West Shelf of Australia, may exhibit a crust layer where the undrained shear strength can be an order of magnitude higher than that of the immediately underlying sediment. This can complicate design of steel catenary risers, where fatigue depends on the cyclic vertical stiffness of the pipe-soil interaction. Potential punch-through of the riser into the underlying soft soil may invalidate design assumptions based on the pipe-soil stiffness within the crust layer. The long-term evolution of pipe-soil stiffness within the crust layer, which exhibits similar properties to an over-consolidated soil, is also poorly understood. This paper describes centrifuge model tests undertaken in a clay sample with a crust layer, simulating the punch-through process of a pipe under load control and investigating the pipe-soil stiffness during long-term cyclic loading tests under displacement control. Results confirm that the potential for punching-through the crust layer depends strongly on the relative ratio of pipe diameter to crust layer thickness. The long-term evolution of pipe-soil stiffness showed a steady increase after an initial remoulding stage in contractile soils (normally consolidated and lightly over-consolidated), but a steady reduction in the heavily over-consolidated, more dilatant, crust. The magnitude of pipe-soil stiffness changes (during both remoulding and reconsolidation) is governed by the over-consolidation ratio of the soil and the amplitude of the cyclic displacements. This study provides insights on the relevant cyclic stiffness to consider when assessing SCR fatigue life in over-consolidated soils and soils exhibiting a superficial crust layer.     

盾构隧道管片接头缩尺试验模拟方法

由于盾构隧道管片接头刚度影响因素繁多复杂，使得缩尺模型管片接头制作困难、模拟效果较差。为此，提出一种采用特制弹簧与预埋螺栓共同工作的管片接头模拟方法来模拟原型管片接头，并分别对该方法设计的模型管片接头以及原型管片螺栓连接接头的轴向、剪切及弯曲刚度进行计算分析。通过对比分析可以得出设计管片模型接头与原型管片螺栓连接接头的等效条件，在满足上述等效条件的情况下，经相似关系换算可认为缩尺模型管片接头刚度与原型管片接头刚度满足试验设定的相似关系。最后，采用堆载试验对模型管片进行可行性验证。经理论分析及模型试验表明： 提出的盾构隧道管片接头缩尺试验模拟方法可使模型接头刚度等效于原型管片接头，能较为全面地满足模拟原型管片的要求。     

高填矩形、拱形截面明洞土压力差异性规律研究

为了得到矩形、拱形截面明洞土压力随填土高度的变化规律,采用模型试验与数值模拟相结合的方法进行研究,得到以下结果： 1）截面形式对明洞土压力大小影响很大,且基础刚度不同,差异性明显。拱形截面明洞洞顶轴线处竖向土压力大于矩形截面明洞。2）刚性基础拱形截面明洞洞顶同一平面竖向土压力变化呈减小-平缓的趋势,而柔性基础呈减小-增大-平缓的趋势; 矩形截面明洞呈增大-减小-平缓的趋势。3）刚性基础明洞洞顶同一平面水平土压力分布形式呈现出2个拱形,而柔性基础明洞仅在洞顶上方出现1个拱形。4）刚性基础拱形、矩形截面明洞洞顶至0.6倍洞高范围内土体位移分别呈“W”、“双V”形分布,0.6～3倍洞高内均呈“V”形分布,3倍洞高以上无相对沉降,而柔性基础明洞土体位移在0～3倍洞高内均为“V”形,3倍洞高以上无相对沉降。     

超大型集装箱船绑扎桥强度校核与结构优化

随着超大型集装箱船的发展,绑扎桥的结构设计越来越复杂。文章在21000TEU超大型集装箱船典型绑扎桥设计的基础上,利用ANSYS软件计算了绑扎桥结构的强度和刚度。通过研究不同浮态,装箱条件以及最大设计载荷条件下结构的总体应力和变形情况,分析了关键位置的应力集中现象。并用这些分析结果指导结构优化,为绑扎桥结构的分析及结构设计提供具指导意见。     

Potential of low viscosity oils to reduce CO2 emissions and fuel consumption of urban buses fleets

This paper shows the results of a comparative fleet test the main objective of which was to measure the influence of Low Viscosity Oils (LVO) over the fuel consumption and CO₂ emissions of urban buses. To perform this test, 39 urban buses, classified into candidate and reference groups depending on the engine oil viscosity, covered a 60,000 km mileage corresponding to two rounds of standard Oil Drain Interval (ODI). In the same way, for 9 buses of the 39 buses, the effect of differential LVO over fuel consumption and their interaction with engine LVO was assessed during the second ODI.Test results confirm that the use of LVO could reduce fuel consumption, hence CO₂ emissions. However, special attention should be taken prior to its implementation in a fleet, particularly if the vehicles are powered by engines with high mechanical and thermal stresses during vehicle operation because this could lead to friction loss increase, loss of the potential fuel consumption reduction of LVO and, in the worst scenario, higher rates of engine wear.     

非刚性轴承润滑与变形耦合下的轴系校中研究

轴承油膜是影响轴系校中的动态因素之一。在油膜刚度的计算过程中,较多学者采用船级社推荐值,或将轴承考虑为刚性,利用差分法或有限元法对其进行求解。文章对轴承弹性变形与油膜压力进行耦合分析,获得最优小扰动量,得到更符合实际情况的油膜刚度,利用vb.net编写有限元轴系校中软件并对某油船轴系进行校中计算,分析了轴承油膜对轴系校中的影响程度,可为船舶轴系校中计算及检验提供参考。     

地下工程注浆技术研究新进展

注浆是土木、水利和矿山等工程建设中重要的防渗和加固技术。文章基于国内外注浆技术研究文献,总结了水泥等颗粒性浆液的“渗滤效应”及“黏度时空变异性”等理论研究成果,论述了非水反应高聚物、CW环氧树脂和微生物菌液等注浆新材料的应用现状及发展前景,介绍了细观力学数值模拟研究的突破性进展,可为地下工程注浆技术发展提供借鉴和启发作用。     

铁路路基动态变形模量的数值模拟分析

介绍铁路路基动态变形模量理论计算公式的推导及动态变形模量的测试原理,采用有限元软件模拟动态变形模量的测试过程,分析承载板与土体接触压力、路基动态变形模量的影响因素,并计算动态变形模量的有效测试深度.结果表明:在承载板中心一定范围内,接触压力模拟结果较理论计算值大;土体的动弹性模量对接触压力影响很小,可以忽略;路基动态变形模量测试冲击荷载作用下,土体只发生弹性变形;动态变形模量与土体动弹性模量呈线性关系,路基动态变形模量的模拟结果大于理论计算值;土体的泊松比对动态变形模量影响较小;动态变形模量有效测试深度建议取0.5~0.6 m.