盾构隧道弯环管片在缓和曲线上的排版研究

目前在地下铁道施工中应用盾构越来越多,由于曲线的存在就要用标准环与转弯环配合拼装,以适应线路的走势。曲线是由一条圆曲线和两条缓和曲线组成。对于圆曲线的管片排版已有了相对较为成熟的理论,而缓和曲线上的管片排版以往通常是根据盾构机VMT来选择,没有成型的理论支持,为此,结合测量理论和弯环管片的实际,探索出在缓和曲线上准确选择弯环管片理论排版的方法。     

山区道路弯道上车辆自动减速系统分析、建模与设计

受弯道离心力影响,在弯道处车辆易发生侧滑和侧翻,山区道路转弯车道为交通事故高发区.车辆自动减速系统运用ITS技术自动控制车辆,使其能以安全车速通过弯道,避免交通事故发生.阐述车辆在转弯道处的运行机理,并对其在直线路段和曲线路段的运行情况分别建立数学模型,且对模型进行解析,以展现车辆自动减速系统的控制过程.通过对数学模型...     

路桥过渡段柔性搭板的设计方法

在对路桥过渡段柔性搭板处治措施的机理进行分析的基础上,参考大比例尺沉降台试验测试数据及有限元仿真与拓扑优化的结果,提出路桥过渡段柔性搭板的布置形式;通过现场调研和资料分析,给出了柔性搭板的合理设计参数参考值。基于模型的受力特点,提出了近似变形曲线的数学表达式,并将计算曲线与试验观测曲线进行了比较。结果表明,计算曲线与实测曲线基本吻合,能够反映真实的沉降情况。在此基础上推导出层间距的计算公式,并给出了设计参数的确定方法,为桥头柔性搭板的设计提供了参考依据。     

基于GTM方法的沥青混合料压实特性分析

借鉴SHRP Superpave沥青混合料设计中密实曲线的分析方法,对比粗、细两种级配沥青混合料的密实曲线,分析集料级配和沥青用量对GTM设计沥青混合料压实特性的影响,提供了一种基于现场压实性能的优化集料级配的方法。     

双车道公路弯道行车轨迹特性研究

采用VTR摄像机记录车辆通过观测断面处的侧向位置,应用Virtualdub视频分析软件判读车辆外侧前轮至道路中心线的距离.选取典型双车道公路上8处曲线为试验段,根据试验数据的统计分析结果,得到以下主要研究结论:车辆在进入曲线段时,行驶轨迹存在着朝曲线内侧偏移的运动趋势;在出曲线段时,车辆行驶轨迹趋向朝曲线外侧偏移;平曲...     

喷嘴喷洒沥青成形形态对喷洒质量的影响

通过对目前国内外所用喷嘴的喷洒试验,得到喷嘴喷洒到地面的成形形态图。根据对喷洒横向曲线图的分析,及与施工照片对照,发现曲线图存在的缺陷与施工存在的缺陷是一致的。对3种假想喷嘴喷洒成形形态作图并叠加得到喷洒横向曲线图,计算出各种喷嘴不同重叠情况下相对于平均喷洒量的误差值,对比、分析后,提出进一步提高施工质量的理想喷嘴喷洒成形形态。     

混凝土单轴受压应力-应变曲线比较

针对目前常采用的混凝土单轴受压应力-应变曲线不能完全符合典型曲线几何特征这一问题,通过理论推导和详细地比较,给出了在单轴受压混凝土应力-应变曲线上升段Hognestad公式、Saenz公式和CEB/FIP公式的适用范围,提出了合理的混凝土单轴受压应力-应变曲线。用大型通用软件ANSYS分析两根试验梁,分析结果与实测结果相当吻合,表明本文提出的应力-应变曲线是准确、可靠的。     

Computer-Simulation of the Dynamical Curving Behaviour of a Railway-Bogie

SUMMARY

This paper describes the modelling of a two axle railway-bogie with variable design configurations and its application in the investigation of the behaviour in transitional and circular curves. Several results indicate possibilities to improve the curving properties and recommend the usage of forced-steering bogies, which show better performance in narrow curves without unbearable sacrifices to high-speed-behaviour on straight track.     

爆破震动信号法判别岩体软弱夹层及其厚度的试验研究

在南宁市郊区一试验场地进行了爆破震动信号判别软弱夹层试验,在试验中采用了无线网络控制的爆破震动信号测量系统,并针对以前试验中的不足,改变了药包起爆顺序和改进了监测点布置方式。试验结果表明:在软弱夹层上方爆破的震动信号时域曲线比较规整简单,频域曲线主峰非常突出明显且高频部分很少;在软弱夹层处及其下方爆破的震动信号时域曲线相对软弱层上方要复杂的多,频域曲线叠加了较多的高频成分,曲线中呈现多峰特性,因此根据爆破震动信号的变化规律可判别软弱夹层是否存在。提出采用应力波初至时刻来计算缓倾斜或水平软弱夹层厚度的简便方法,并进行了试验,试验结果表明软弱夹层厚度是近似均匀分布的。     

A Qualitative Analysis of the Dynamics of Self-Steering Locomotive Trucks

The primary purpose of this study is to provide a qualitative analysis of the dynamics of the self-steering trucks that are commonly used for freight locomotives – namely, EMD's Radial Truck and GE's Steerable Truck – on improving curving performance and increasing adhesion in curves. Although there exists a number of anecdotal statements on the ability of steerable trucks to reduce curving forces and increase adhesion in curves, to the best of our knowledge, there exists no study that provides a qualitative or quantitative analysis of these features of steerable trucks. Two aspects of locomotive trucks are essential for their ability to deliver small curving forces and high adhesion in curves. First, the ability to allow the axles to yaw sufficiently relative to the truck frames, such that they can hold a small angle of attack with the rail. Second, providing sufficiently large longitudinal stiffness between the end axles and the axles and truck frame, to accommodate high adhesions. An equivalent stiffness analysis is used to show that the two steerable trucks that are considered for this study are far superior to conventional, three-axle, straight trucks in providing both a smaller angle of attack and a higher longitudinal stiffness for better curving and adhesion characteristics. The qualitative analysis of this study agrees with the experience the railroads have had with their self-steering trucks. The findings of this study indicate that self-steering trucks can result in lower lateral forces, accommodate tighter curves, and deliver higher adhesion in curves; without lowering the critical hunting speed of the locomotive. The results further show that the steering mechanism stiffness can have a large effect on the lateral, longitudinal, and yaw stiffness between the end axles; therefore, significantly lowering curving forces, and increasing adhesion and critical hunting speed of the truck.     

开采影响下高等级公路的防护措施探讨

探讨了高等级公路在采动影响下的地面维修措施和井下开采措施.其中地面维修措施主要包括加高路基、加宽路基、灌浆处理采动裂缝;调整超限的坡度、竖曲线、平面圆曲线和超高;修理不平整的路面和损坏的涵洞;采动前在水泥混凝土路面上设置变形缝,减小水泥混凝土路面单体的长度,以增大抵抗水平变形的能力;对重要的涵洞进行采前加固或改为管涵,...     

A Qualitative Analysis of the Dynamics of Self-Steering Locomotive Trucks

The primary purpose of this study is to provide a qualitative analysis of the dynamics of the self-steering trucks that are commonly used for freight locomotives - namely, EMD's Radial Truck and GE's Steerable Truck - on improving curving performance and increasing adhesion in curves. Although there exists a number of anecdotal statements on the ability of steerable trucks to reduce curving forces and increase adhesion in curves, to the best of our knowledge, there exists no study that provides a qualitative or quantitative analysis of these features of steerable trucks. Two aspects of locomotive trucks are essential for their ability to deliver small curving forces and high adhesion in curves. First, the ability to allow the axles to yaw sufficiently relative to the truck frames, such that they can hold a small angle of attack with the rail. Second, providing sufficiently large longitudinal stiffness between the end axles and the axles and truck frame, to accommodate high adhesions. An equivalent stiffness analysis is used to show that the two steerable trucks that are considered for this study are far superior to conventional, three-axle, straight trucks in providing both a smaller angle of attack and a higher longitudinal stiffness for better curving and adhesion characteristics. The qualitative analysis of this study agrees with the experience the railroads have had with their self-steering trucks. The findings of this study indicate that self-steering trucks can result in lower lateral forces, accommodate tighter curves, and deliver higher adhesion in curves; without lowering the critical hunting speed of the locomotive. The results further show that the steering mechanism stiffness can have a large effect on the lateral, longitudinal, and yaw stiffness between the end axles; therefore, significantly lowering curving forces, and increasing adhesion and critical hunting speed of the truck.     

孤石形状与岩土介质对孤石探测的影响研究

采用现场试验和数值模拟相结合的方法,针对不同孤石形状、不同周围岩土介质对地质雷达探测孤石结果的影响进行研究。结果表明:不同形状孤石的雷达波形反射曲线形状有差异,其中球状孤石的反射波形大致为一条双曲线,且曲线较为平滑规则,而块状孤石的反射波形为左右两条双曲线与前部扁平线的组合形状;球状和块状孤石反射曲线中间反射能较大,而曲线两侧翼部反射能较小;球状与块状孤石的反射弧跨度随着截面尺寸的增加呈线性增长,且在相同截面尺寸下两者大致相同;在砂土介质中,孤石处的雷达反射波形比在黏土介质中明显,故周围岩土介质对地质雷达探测孤石结果的准确性有一定的影响。     

铲土运输机械作业组合系统的优化

在绘制出不同作业距离段铲土运输机械的作业生产率和单位土方施工成本曲线后，把各段曲线拟和成多项式并数字化，再经过生产率和成本方程的规格化处理，建立起评价方程，并利用该方程可对机械组合系统的综合作业指标进行定量分析和作业组合方案实行优化。     

不同半径和缓和曲线的复曲线计算与敷设

在道路线路设计时,为适应特殊地形,常设置两个不同半径和不同缓和曲线同向相接的复曲线。对于复曲线的计算,相关文献都有各自的方法。根据对缓和曲线构成原理及选线测设的实践经验,提出一种复曲线的计算和敷设方法,较为简便、快捷。     

How do dutch drivers perceive horizontal curves on freeway interchanges and which cues influence their speed choice?

Operating speeds in Dutch freeway curves differ often by 20 km/h compared to their design speeds. Operating speed is thought to be influenced by how drivers perceive curves when approaching a curve. This explorative research explores which curve cues and other variables influence drivers’ speed choice in curves. For this purpose, a survey was designed with 28 sets of curve comparisons. The curves were chosen from interchanges in the Netherlands and were compared to each other. To avoid direction bias, the curves were right turning only. In each set illustrations of two different curves out of a total of 8 curves were shown, and the participants were asked in which curve they would drive faster. In total 819 participants in the age range of 18 and 78 (mean=41.3; Std.=11.9) completed the survey. The survey data showed four common categories of curve cues and variables influencing the decision to drive faster, of which those in the category of the road environment and its surroundings were mentioned the most. The top three variables influencing speed choice are visibility of curve characteristics, “overview” as a holistic but as such hard to measure variable, and number of lanes. Variables such as presence of signage and trees were also mentioned frequently by the respondents. Geometric road characteristics such as curve radius and deflection angle were identified by the respondents as influencing variables, but only showing to affect speed selection when these are visible to the driver and not obscured by trees or other elements. This suggests combinations of geometric and surrounding elements are needed to get a better understanding of speed selection by drivers.     

Excel在道路中线逐桩坐标计算中的应用

不论是在铁路还是公路的设计和建设中都不可避免地遇到大量的曲线计算。城市轻轨、地下铁道、水建工程等大型工程亦是如此。红外测距仪、全站仪的广泛应用，使得坐标法曲线放样的应用更加广泛。手工计算器计算，耗时、费人且易出错。数据处理软件——Excel——具有强大的计算功能，将其应用于曲线计算，会极大地节约计算量，简化计算过程，起到事半功倍的作用。结合工程实例，介绍了相应的计算方法。     

冻融循环作用下黄泛区饱和含盐粉土动力性能及细观损伤演化规律

山东省黄泛区地处季节性冻土区,当地大量采用含盐粉土修筑公路路基,冻融循环作用后路基土动力性能受损,在车辆荷载作用下会发生路基翻浆病害。为研究冻融作用、盐分含量对饱和路基粉土动力性能及细观结构特征的影响,针对不同含盐量粉土开展有侧限封闭冻融试验,采用振动三轴试验测试多次冻融作用后解冻状态土样的骨架曲线、动模量和动阻尼比,同时采用核磁共振技术测试经历多次冻融循环后解冻状态饱和土样的横向驰豫时间T₂谱曲线。研究结果表明：冻融作用后动应力幅值与动应变幅值之间符合修正的Hardin-Drnevich模型,当冻融6次后骨架曲线趋于稳定;初始动模量损伤度随冻融循环次数呈双曲线型增大,氯化盐含量小于12%时,随含盐量增加初始动模量损伤度呈线性增大;阻尼比随动应变幅值增大增加明显,随盐分含量、冻融次数增加而增大;随冻融次数增多,T₂谱曲线主峰信号强度幅值减小,同时会产生横向驰豫时间长的波峰;T₂级配曲线趋于连续光滑,形态趋于相似,不均匀系数和曲率系数趋于稳定;无盐粉土T₂级配曲线的不均匀系数逐渐减小,并约稳定于5.6,曲率系数先减小后增大,并约稳定于0.986;当经历冻融6次后,随含盐量增加,T₂级配曲线不均匀系数先增大后减小,曲率系数先减小后增大。     

基于行驶轨迹的双车道公路弯道路段交通安全特性研究

针对双车道公路曲线路段碰撞事故高发的特点,选取某双车道公路5个简单平曲线,实测弯道路段车辆行驶轨迹,分析大货车、大客车、小货车和小客车等主要车型在上行、下行方向的轨迹中线偏移量,研究不同车型的行驶轨迹偏移特性.通过测定不同车型在不同半径平曲线行驶的轨迹交叉面积,建立车型、平曲线半径与行驶轨迹交叉面积关系模型,为双车道公...     

发动机冷却系统匹配设计的性能曲线关联法

散热器散热能力的评估需要压降-流量曲线和换热量-流量曲线。传统方法只是选定某个工况分别评估两条曲线,甚至仅仅选定某个工况点的压降值和换热量值。文章介绍的新方法是定量地将两条曲线关联起来评估散热器性能。此方法更具理性、科学性和实用性,有助于通过零部件数据分析来设计发动机冷却系统,节约开发成本和时间。