拉日铁路年楚河特大桥V形刚构加拱组合结构设计

拉日铁路年楚河特大桥主桥采用(60+148+60)m V形刚构加钢管混凝土拱组合结构,桥型结构新颖,详细介绍该桥型的设计特点,对主桥进行静力及动力分析,对承载能力、抗震、车桥动力响应等方面进行了详细计算。该桥将V形连续刚构和钢管混凝土拱桥2种体系有机结合在一起,使V构与拱在受力方面的优点得以充分发挥,既能保证安全舒适的行车,又满足了景观造型要求。     

高速铁路开行160km/h普速列车信号系统适应性研究与应用

针对目前160 km/h普速列车上线高速铁路运行的需求,进行技术方案可行性分析,从普速列车运行到动车组安全防护、过走防护进行研究。最后以兰新第二双线为例,提出适应实际工程的普速列车上线运行的技术方案。     

大跨度三主桁连续钢桁梁桥受力特性研究

为研究横向构件布置与截面设计对3主桁受力均衡性的影响,以宁波市三官堂大桥主桥160m+465m+160 m=785 m的大跨径钢桁架连续梁桥为例,采用Midas/Civil软件建立钢桁架梁模型,分析比较对称荷载与偏载作用下主桁结构支反力、轴力和位移等静力效应,得出了3主桁连续钢桁梁桥的内力分布特性.     

铁路瓦斯隧道施工特点及问题探讨

通过对铁路瓦斯隧道现有施工规范分析,并参考《煤矿安全规程》,对铁路瓦斯隧道施工特点进行总结;同时通过对相关条款的分析、研究,并对照国内已发生的瓦斯隧道施工、低瓦斯矿井生产事故,对现有规范中存在的问题进行探讨,提出以下建议：1) 进一步明确进洞管理系统的标准和要求;2) 进一步明确和细化瓦斯隧道电力供应原则;3) 进一步明确和改进瓦斯隧道机电设备防爆性配备的原则和相关条款。     

Contents Index Volume 35 and 36

Active safety systems would benefit from tyre force and friction potential information. Different sensor concepts, including, among others, the EU–funded Apollo–project developed tyre sensor based on optical position detection, are being studied. The sensor can measure tyre carcass deflections with respect to the rim. The carcass deflections can be used to calculate tyre forces and they may be exploited in the estimation of friction potential. The waveforms of the sensor signal are illustrated. The vertical and lateral force estimations are presented with unavoidable compensation parts. The tyre sensor measurements were compared to the measurement–vehicle results and good correlations achieved. Continuing activities are concerned with the estimation of friction potential and the detection of aquaplaning.     

A model-based traction control strategy non-reliant on wheel slip information

A traction control system (TCS) for two-wheel-drive vehicles can conveniently be realised by means of slip control. Such a TCS is modified in this paper in order to be applicable to four-wheel-drive vehicles and anti-lock braking systems, where slip information is not readily available. A reference vehicle model is used to estimate the vehicle velocity. The reference model is excited by a saw-tooth signal in order to adapt the slip for maximum tyre traction performance. The model-based TCS is made robust to vehicle modelling errors by extending it with (i) a superimposed loop of tyre static curve gradient control or (ii) a robust switching controller based on a bi-directional saw-tooth excitation signal. The proposed traction control strategies are verified by experiments and computer simulations.     

Influence of some vehicle and track parameters on the environmental vibrations induced by railway traffic

A study is performed on the influence of some typical railway vehicle and track parameters on the level of ground vibrations induced in the neighbourhood. The results are obtained from a previously validated simulation framework considering in a first step the vehicle/track subsystem and, in a second step, the response of the soil to the forces resulting from the first analysis. The vehicle is reduced to a simple vertical 3-dof model, corresponding to the superposition of the wheelset, the bogie and the car body. The rail is modelled as a succession of beam elements elastically supported by the sleepers, lying themselves on a flexible foundation representing the ballast and the subgrade. The connection between the wheels and the rails is realised through a non-linear Hertzian contact. The soil motion is obtained from a finite/infinite element model. The investigated vehicle parameters are its type (urban, high speed, freight, etc.) and its speed. For the track, the rail flexural stiffness, the railpad stiffness, the spacing between sleepers and the rail and sleeper masses are considered. In all cases, the parameter value range is defined from a bibliographic browsing. At the end, the paper proposes a table summarising the influence of each studied parameter on three indicators: the vehicle acceleration, the rail velocity and the soil velocity. It namely turns out that the vehicle has a serious influence on the vibration level and should be considered in prediction models.     

Investigating the influence of soil properties on railway traffic vibration using a numerical model

This paper presents the influence of dynamic and geometrical soil parameters on the propagation of ground vibrations induced by external loads. The proposed approach is based on a three-dimensional model, focusing on realistic excitation sources like impulse loads and moving railway vehicles. For the latter, a complete vehicle/track model is developed. The simulation is performed in time domain, offering an interesting approach, compared with classic cyclic analyses. The ground is modelled initially as an elastic homogeneous half-space and additionally as a layered half-space. First, the effect of homogeneous soil properties on ground vibration is analysed. Soil stratification is then taken into account, using various configurations. Analysis reveals that as receiver distance increases ground wave reflection in a layered ground plays an important role in the reduction of ground surface motion. This effect is magnified when the phase velocity wavelength becomes large compared with the depth of the surface layer.     

滚装船冷却水系统的优化设计与热力性能研究

本文以12300t滚装船为母体,运用非线性规划理论对独立式和混合式两套冷却水系统进行了优化计算和分析,并对其冷却水系统的冷却效果和经济性进行了评估.同时还对其多主机双套冷却水系统进行了热力性能研究,对其在系统额定热负荷下和变负荷下的热力特性进行了分析计算,通过计算定量地揭示出其冷却系统的节能潜力.上述分析和研究为今后用以指导冷却系统的运行管理,以及为系统节能降耗提供了科学而准确的依据.     

单侧边载作用下黏土中单桩负摩阻力特性模型试验研究

桩基础边载作用会在桩周产生负摩阻力,进而危及软土地区高桩码头、人工岛、路基等工程的安全。通过开展黏土中单侧堆载作用下单桩室内模型试验,测定桩身应变、桩顶沉降和水平位移,研究边载作用距离和桩型对桩身轴力及弯矩的影响,探讨桩身负摩阻力、桩顶沉降和水平位移在黏土固结过程中的时间效应。结果表明:边载作用距离对桩身最大轴力和最大弯矩有较大影响;翼板桩会增加桩身最大轴力和最大弯矩;负摩阻力和有效应力系数随时间增长且增速趋缓;增加边载作用距离和添加翼板都会提升桩身中性点位置,在这两组试验中均提升了8.33%。