This study conducted comprehensive experimental and modeling investigations on compressive properties of polyurethane grout materials with the density of 0.08 0.5 g·cm-3 .SEM and uniaxial compression tests were applied to specimens with varied density.Parameters obtained from SEM images were employed to predict compres-sive strength.It is found that foams in higher density specimens are spheres owning less contact area,which ensures the system stability based on the minimum energy principle.While majority foams in lower density specimen are polyhedrons and their contact area is larger.The uniaxial compression can be divided into elastic (strain less than 5%),yield (strain from 5% to 50%)and densification (strain higher than 50%)stages.In elastic stage,strain of higher density specimen develops faster with normalized stress,while the corresponding stress at yield stage can be viewed as compressive strength and develops with density,and in densification stage higher density specimens are characterized with brittle failure.Gibson-Ashby model based on geometric parameters of foams obtained from SEM image can be used to predict the compressive strength,and materials with varied density characterized with different strength can be applied in infrastructure maintenance.

分析了CRCP+ AC复合式路面结构塑性损伤,研究了不同荷载作用条件下结构应力与损伤的空间分布规律.利用正交试验方法,以结构的拉张损伤作为考察指标,对多种复杂的结构因素与环境因素进行了参数敏感性分析,得到了各因素影响规律.根据极差、方差分析结果,区分了变温作用、温度与荷载耦合作用条件下的主要与次要因素,并依据影响效果进行了次序排列.研究结果表明:结构损伤在CRCP面板深度范围内的分布存在差异,导致拉应力的差异化分布;重复行车荷载作用时,随着结构应力软化现象的加剧,结构损伤在初期呈现台阶式上升趋势,后期则增长平稳;根据结构最大塑性主应变的矢量方向可判断结构裂缝平面的法向;综合考量不同荷载作用的分析结果,沥青面层厚度、混凝土的线膨胀系数与面板的支撑情况是影响CRCP结构损伤最为重要的因素.

In accordance with the application characteristics of front end processor(FEP)in the integrated supervisory control system(ISCS)of urban rail transit and based on analyzing the advantages and disadvantages of various FEP network options,two designs are proposed for running FEP software on servers.All FEP functions can be achieved in FEP software and the adaptability of FEP to ISCS is analysed in terms of performance,data security,reliability and cost.

Median opening space is a key problem when vehicles' left turn is forbidden and indirect turn must be done at downstream section.Using freeway weaving theory for reference,the median opening spacing model of indirect left turn is developed,and micro-simulation is carried out.It is found that the average delay of indirect left turn with the spacing model is reduced by 4.6 s compared with the direct left turn,and the effect is remarkable when the distance of adjacent intersection is long and the road design speed is not fast.5 tabs,4 figs,14 refs.

为了制定合理的轨道交通线网票价,从政府、运营企业和乘客三方面对选取票价制定方法进行了详细分析.以影响因素为准则、以各种票价制定方法为方案,建立轨道交通票价制定层次分析法选择模型.算例分析得出平均运营成本定价、拉姆塞定价和博弈论定价三种方法的层次总排序向量为(0.325 8,0.346 6,0.327 6),拉姆塞定价方法最符合该城市轨道交通实际.

In order to make reasonable transfer preferential benefit policy of public transport,the generalized cost including direct cost was introduced into Logit model to study the influence of fares.Through the actual traffic investigation,the parameters were determined,and the effectiveness of the model was proved by calculated the actual traffic modes split rate.In the constraints of public transport's supply,the expected split rate of public transport was determined after the implementation of transfer preferential benefit.When other non-preferential measures are known,the amount of transfer preferential benefit can be determined.Example analysis shows that this method can target down to 40% of the split rate of private car.

There is no level of service (LOS) evaluation system for urban rail transit in China at present. In order to quantitatively evaluate the LOS for urban rail transit as well as to find out the difference between current service situation and trip demands, the orientation to enhance LOS is highlighted. According to customers’view and their trip decision-making process, the evaluation factors which can impact the LOS are chosen based on some principles. The indexes corresponding to the evaluation factors are divided into different levels. The evaluation system of LOS for urban rail transit which can fit the situation of China is planned on the basis of summarizing the successful experience achieved abroad.

Loading pattern is the basis of mechanical analysis of steel deck pavement.In this paper,3-D FEM was used to simulate the contact process between tire(265/70R19.5)and deck pavement.The characteristic of contact area and stress distribution was stud- ied.The results show that the contact area and stress between tire and pavement vary with the vehicle axle loading.When axle load- ing reaches 100kN,the contour of contact area is approximately rectangle;and when the tire is above the web of U stiffeners,the distribution of uprightness stress in the contact area is near peak type,and when the tire is on the pavement between webs of stiffen- ers,the distribution of uprightness stress is near concave type.Therefore,double rectangles loading pattern can simulate the contact between tire and pavement better than others,and the loading density should be chosen after the unfavorable position of the tire is considered properly.

Based on the Runyang Yangtze River Highway Bridge, which consiss of one cable-stayed bridge of South Branch and one suspension bridge of North Branch, the three-dimensional overall bridge model was established using the FEM numerical simulation to analyze the bridge deformation and mechanical performance. And a global-local analysis method was proposed to study the mechanical properties of surfacing. The shape of suspension bridge has large effects on the mechanical performances of the surfacing. The tensile stress obtained in this paper is significantly bigger than those by the traditional model. For the central section of the cable-stayed bridge, the mechanical indexes values of the surfacing obtained by this method are little bigger than those by the traditional model; otherwise, for the other sections of the main girder that undertake the horizontal component compression of the cable, the tensile stress values of the surfacing are little smaller than those by the traditional model.

文章首先给出二维弹性层状理论下钢桥面铺装体系温度应力,在此基础上,提出应用二维粘弹性层状理论对钢桥面铺装体系的温度应力进行计算,并将计算结果与二维弹性层状理论体系及国际通用有限元计算软件SAP程序的计算结果进行了比较.同时,以国内某大跨径钢桥试验桥的铺装层结构体系为对象,研究了其周期性变化的温度应力,分别探讨了连续降温、不同降温速率及铺装层厚度变化对铺装层温度应力的影响.

The stress intensity factor(SIF)for the surface crack of the pavement on orthotropic steel bridge decks is calculated and analyzed.The Paris'formula is employed to forecast the fatigue life of the pavement.A three-dimensional fracture-mechanics finite element model of orthotropic steel bridge deck systems is developed.According to the change in the SIF with the change in the loading position of the axle-load,the worst loading position of the axle-load on the cracking pavement of the steel bridge deck is determined,the change in the SIF with the change in the crack depth is analyzed,and the relationship between the SIF and the crack depth is established.The expression of the SIF is substituted into the Paris'formula,and the fatigue life of the pavement is calculated by using an integral of the Paris'formula.The result indicates that fracture mechanics can be employed to forecast the fatigue life of the pavement on orthotropic steel bridge decks.

For the demand of intelligent management at intersections in cities, one sort of vehicle tracking system based on Labview is designed. The video is acquired by being equipped with ordinary video acquisition board and using dynamic link lib technique. On this basis, combined with one sort of background updating model, vehicle tracking algorithm is presented through using two-dimension motion estimation technique in dynamic image processing. The experiment results show that vehicle tracking algorithm is robust and the tracking success rate can reach to 90%-95%.

The effect of stone powder contained in artificial sand on the concrete performance was studied in this paper.The results showed that the higher the stone powder content within the limit less than 24%,the higher of the concrete strength and the better of frost resistance and impermeability;and the carbonation and steel corrosion properties of stone-chip concrete were not worse than those of ordinary concrete.Furthermore,the acting mechanism was researched by XRD, TG and SEM.It is believed that the effects of filling,nuclei,shape,sopping up and activity of stone powder would improve the performances of concrete.

The epoxy asphalt concrete is a good kind of paving material for steel bridge decks,but its performance can be influenced obviously by construction conditions.Basing on practical construction experiences,authors provide requirements of epoxy asphalt concrete from such aspects as selection of materials,composition,and construction and so forth in order to effectively control construction quality and to realize performances of this materials.

环氧树脂沥青材料是一种采用环氧树脂改性的结合料,其混合料的路用性能受结合料的粘弹性能影响较大.采用-15,0,10,20,30,40℃温度下的压缩蠕变试验,分析了环氧树脂沥青材料的蠕变特征,利用时温等效原则和WLF方程,建立了环氧树脂沥青材料的主曲线,构建材料的粘弹性方程,并分析了交联对材料粘弹性能的影响.通过研究,揭示了环氧树脂沥青材料的粘弹特性,可以用于其配方优化设计.

由于路面破损形式的多种多样,造成路面破损分类[1]成为一大难题,这极大的限制了路面破损自动检测的普及和发展,使得路面破损自动检测即使在发达国家也普及得不够理想.本文在前文提出的破损密度因子的基础上,进一步设计了出方向密度因子,得到一种基于图象子块分布特性的路面破损识别算法.通过仿真,验证了其对常见的5种路面破损类型进行分类的可行性.为了进一步验证我们提出的识别算法,论文选择了另外一种路面破损分类算法,即PROXIMITY算法进行神经网络仿真对比.神经网络的训练样本是两组,测试样本也是两组,进行了四次仿真对比.四次仿真结果都显示方向密度因子算法优于PROXIMITY算法.

首先提出了大跨径钢桥桥面铺装设计基本原则,接着选取大跨径钢桥桥面铺装设计的标准轴载,并给出设计年限内一个车道上标准轴载的累计当量作用次数换算公式.然后根据大跨径钢桥桥面铺装设计必须控制的主要破坏形式,提出了桥面铺装厚度设计控制指标和验算指标及其容许值的确定方法.给出了大跨径钢桥桥面铺装设计涉及的材料特性参数及其试验方法,最后给出大跨径钢桥桥面铺装设计步骤及框图,并提供一个设计算例.

This paper investigated the damage conditions of mastic asphalt pavement on orthotropic steel deck plate, analyzed the damage causes, including the properties of pavement materials, mechanical conditions with different truck load, traffic content, and so on. Analysis results indicate that failure of high-temperature stability and fatigue property, overload and slow velocity of trucks, heavy and dense traffic are the main causes for the damage. 5 tabs, 10 figs, 6 refs.

The deck pavement of many long span steel bridges have damaged at their early operation stage. The damage still occurred after rehabilitation. The key fact is that the current design method of asphalt mixtures is not suitable for deck pavements of long span steel box bridges. Typical damages of steel deck pavements occurred at early stage and their characters are summed up. The requirements for deck pavements of a long span steel bridge are analyzed. Deficiencies of the current design method of steel deck pavements are discussed. On the basis of the requirements and inefficiencies of the current design method of asphalt mixture, a new design method of asphalt mixture named “three-stage mixture design method” are proposed.

结合图象处理、模式识别等先进技术开发路面破损自动检测系统已经成为本领域的研究热点.要提高识别率,适当的裂缝分类及其数量的统计方法显得十分重要.在系统总结分析前人的研究成果的基础上,本文提出一种路面破损裂缝的分类和数量统计的新方法--基于破损密度因子的路面破损评价和分类方法.文中对破损密度因子进行了定义,并且,用本文的方法与一些已存在的方法进行了比较分析.结果表明,本方法不仅简单,实用,而且在算法的平移不变、旋转不变、和反映路面实际破损程度方面都优于其它方法.