防冰沥青混合料是一种具有主动防冰效果的沥青混合料,为研究防冰沥青混合料的路用性能及防冰效果,采用常规的试验方法研究防冰沥青混合料的路用性能,采用研发的防冰冻试验、拉拔试验和除雪试验对比评价普通沥青混合料和防冰沥青混合料的防冰效果,分析防冰沥青路面的耐久性。室内研究结果表明防冰沥青混合料在原材料和级配符合使用条件下,具有较好的实际路用性能和防冰效果。在室内研究的基础上,铺筑了试验路,通过试验路使用性能的观测,验证了防冰沥青混合料具有较好的防冰效果。
To research the influence of the contact condition between a semi-rigid base and asphalt surface course on the mechanical responses of the pavement structure and on fatigue life, a typical pavement structure is chosen and a shear spring compliance from the software Bisar 3.0 is used as the evaluation index of the interlayer contact condition to conduct the mechanical response calculation of the pavement structure and to analyze the change law of the stress, strain, and deflection under different contact conditions. and then the fatigue life of the pavement structure is calculated under different contact conditions. The results show that the shear spring compliance can quantitatively characterize by the interlayer contact conditions between the base and surface course. The interlayer conditions have a significant impact on tensile stress and shearing force. When the interlayer contact pattern changes from a continuous state into a sliding state, the growth rate of the tension stress of the bottom of the asphalt layer is 528.25% and growth rate of shear stress is 157.3% while the interlayer conditions have a smaller impact on deflection.
The autogenous shrinkage of pavement concrete with different water to cement ratios are measured in an experimental setup, and these samples' gradation and pore structure characteristics are analyzed by a mercury intrusion method and an optical microscope with the Image Pro-Plus software package. The autogenous shrinkage model of pavement concrete with 0.38-0.44 water to cement ratio is established. The results of the shrinkage mechanism analysis show that pores with a diameter less than 100 nm play a vital role in autogenous shrinkage, varying the water supply volume only changes the number of capillary pores, and varying the cement volume changes the capillary number, the total porosity of the mixture, the average pore diameter, and the pore space factors.
为研究常温沥青混合料强度形成机理与影响因素,采用马歇尔试验方法,系统测定不同级配类型和沥青用量、不同成型方式、击实功、养护周期和养护方式等试验条件下的马歇尔稳定度。试验结果表明:(1)采用悬浮密实型级配有利于常温沥青混合料早期强度的形成,且随沥青用量的变化,混合料强度存在一个最大值;(2)击实功和养护周期是影响常温沥青混合料强度形成的主要外因,双面各击实130次后强度增长才明显缓慢,经49 d养护后强度才最终形成;(3)常温沥青混合料的强度形成具有时间性和过程性,车辆轮碾压密作用促使φ值增大,时间推进、溶剂挥发促使c值增大;在轮碾和时间双重因素作用下,c、φ值同时增大,混合料强度形成更快。
由于沥青和沥青混合料为黏弹塑性体,而荷载又是影响沥青路面高温稳定性的关键因素,沥青路面出现车辙的概率极大提高。利用荷载轮轮速、温度、荷载均可变化的车辙仪,以动稳定度为技术研究指标,研究温度变化、荷载作用时间变化、荷载大小变化对沥青混合料高温稳定性的影响,进而研究三者之间的等效作用。试验结果表明:温度、荷载作用时间、荷载大小对沥青混合料高温稳定性均有显著影响,三者之间具有一定的等效作用,但在各因素比较宽的变化范围内并无明确的等效关系。
Expansive soils in cut slopes are prone to sliding for a period of time after excavation. They are commonly found during construction in expansive soil subgrade. Their sliding is not directly affected by the height and ratio of the slope. To understand the evolution of their deformation and the consequences of failure to implement effective engineering treatment, the finite difference procedure FLAC is used to analyze the regularity of the excavation process of expansive soil slopes and obtain the displacement, stress, and strain. The safety factor for slope cutting calculated by using the strength reduction method decreases as the slope depth increases, but is still stable after the complication of excavation. In addition, the thermodynamics module of the finite difference procedure FLAC is used to simulate the humidity field of the atmospheric effects for the expansive soil slope and to obtain the variability of the displacements, stresses, and strains of the cut slope after wetting and drying cycles. The numerical simulation results are basically in accordance with field observation results during and after the construction of cut slopes in the Sitang interchange ramp of the Bailong expressway in Guangxi Zhuang Autonomous Region, China. The four stages of evolution of expansive soil cutting slopes are summarized. It is proposed that flexible supporting structure technology should be used.
为了提出沥青混合料紫外光老化评价指标,通过沥青砂来研究沥青混合料的流变特性,制作沥青砂试件进行室内加速紫外光老化试验,分别进0、2、4、6、8、12个月的紫外光老化。对老化的试件在恒定荷载0.1 MPa的作用下,保持恒定温度20℃进行单轴压缩蠕变试验,得到应变-时间关系曲线。采用Burgers模型描述沥青砂的流变性能,并根据应变-时间关系进行Burgers模型4参数的拟合,拟合得到不同老化时间对应的黏弹性参数值,对该值进行拟合,得到黏弹性参数和老化程度的关系式E1(h)、E2(h)、η1(h)、η2(h),把该表达式代入Burgers模型的本构方程表达的蠕变柔量方程中得到蠕变柔量J(t)和老化时间的关系式J(h,t),提出用J(h,1 200 s)作为沥青混合料紫外光老化的评价指标。
To cope with the phenomenon of moisture imbalances in subgrades due to excavation, the resistivity of different excavation subgrades (deep excavation section, shallow excavation section, and cut-and-fill transition section) at different vertical depths pre- and post- excavation of blind drains were measured using temperature and resistance sensors laid in test sections of the Zhangjiakou-Zhuozhou expressway project.The moisture migration characteristics in excavation subgrades were analyzed by developing the relation between resistivity and moisture content from laboratory experiments.The analysis results show that (1) the moisture contents in subgrades in late autumn and early spring increases with an increased excavation depth, which is due to the combined effect of the temperature and water supply from excavation slopes; (2) blind drains and the roadbed replacement depth contribute to the suppression of moisture migration in excavation section subgrades, which can improve the work state of the subgrade; (3) summer rainfall significantly influences moisture migration in deep excavation section subgrades and cut-and-fill transition section subgrades; the moisture content in summer significantly increases compared with that in the other seasons; the influence of seasonal factors on moisture migration in deep excavation section subgrades is significantly stronger than that in cut-and-fill transition section subgrades.
双层摊铺压实质量控制较传统摊铺更为重要,为了建立在同等压实功下沥青路面双层摊铺与传统摊铺厚度等效转换关系,以中面层AC-20为研究对象通过室内正交试验设计借助非标准马歇尔试验分析了温度、厚度对混合料压实度的影响程度并进行对比分析,在柯布-道格拉斯方程基础上应用麦夸特(Marquardt)方法并借助DPS数据处理系统获得混合料压实度与温度、厚度之间的定量关系。试验分析结果表明:混合料温度对压实度的影响比厚度对压实度影响大,保证了在一定范围内的双层摊铺混合料压实度能够满足规范要求;混合料密度同温度、厚度存在定量关系ρ=2.162T0.119H-0.113;依据混合料密度同温度、厚度定量关系得到,双层摊铺10 cm沥青混凝土相当于传统摊铺8.8 cm。
The bearing capacity of soils under highway engineering differs from that of soils under the building foundation as a result of different superstructure types and foundation forms. Determining the characteristic value of highway bearing capacity by directly adopting the evaluation method from building codes is conceptually indefensible because such codes do not represent the real bearing capacity of highway foundations. By analyzing the superstructure types and foundation forms of highway subgrade, bridge, culvert, and building, the evaluation methods of highway foundation, bridge, and culvert are determined. Furthermore, a three-level classification system of highway foundations is presented and a highway engineering bearing capacity evaluation system based on Geographical Information Systems (GIS) is established. By using the spatial data management and spatial data analysis platform of GIS and by combining the plate-loading testing data and engineering properties of different soils, the system accomplishes the effective evaluation of the bearing capacity beneath the highway subgrade, bridge, and culvert, and provides a theoretical basis and practical reference for the evaluation of the bearing capacity and the choice of ground improvement in engineering design and construction.
为使所建道路技术可靠、经济合理,将价值工程理念引入到路面结构决策中。首先依据山东省近十年的国省道调研资料,建立不同交通水平和沥青层厚度下国省道沥青路面使用性能模型参数,以此为基础提出了道路使用功能的评价方法;然后对一定分析期内路面的初始投资、日常养护、中修费用进行了分析,以寿命周期费用方法计算一定分析期内的经济投入;最后以轻交通和中等交通为例,使用价值工程方法对6~10 cm沥青层厚度的道路使用功能和费用进行了计算比较,结果表明轻交通时8 cm厚沥青面层的价值最大,中等交通时10 cm厚沥青面层价值最大。
To solve the problem of identification damage in a cantilever retaining wall, a damage identification method for such a wall, based on the flexibility-difference mean curvature, is proposed. The concept of mean curvature in differential geometry is introduced to calculate the flexibility-difference mean curvature. First, the flexibility difference matrix is calculated using the change in the modal flexibility matrix of the before and after damage in the retaining wall, and each column average value of the flexibility difference matrix is used as an element of the modal flexibility-difference column vector. Then, the flexibility-difference mean curvature (FDMC) is obtained using the central difference method, as a new index of damage identification. The result of a numerical simulation of the cantilever retaining wall indicates that (1) the damage location in a retaining wall, single damage or multiple damages, can be detected accurately using FDMC and (2) the unit damage extent can be accurately detected via the relation between the damage extent and the index FDMC with high precision. Further, the effectiveness and advantages of FDMC as compared to the Gauss curvature modal difference are proven.
目前尚无沥青路面节能减排量化评价指标及评价方法。首先从沥青路面节能减排评价的需求出发,确定资源利用、能源消耗、环境排放、管理控制和路面技术5个1级评价指标及其2级指标,并根据节能减排评价目标与要求,分别确定定量评价指标与定性评价指标的基准值。然后结合专家调查意见,采用层次分析法确定1级评价指标和2级评价指标的权重。最后以模糊综合评价方法为基础,结合加权综合得分,建立了初审-评价-分级3阶段的沥青路面节能减排综合评价方法。
The finite element software ABAQUS is used to analyze the influence of hinge joint crack on transverse load distribution of prefabricated concrete hollow core slab bridge, including single-side crack and two-side crack. The relationship between hinge joint crack length and load transverse distribution was built by using the Regression Analysis. Equivalent Area Method was adopted to bring out the critical crack length. The paper introduced a correlative method to illustrate single plate phenomenon and suggested the critical hinge joint crack lengthens for prefabricated concrete hollow slab bridge, which provided a technical basis for the quantitative assessment of single plate phenomenon in the technical inspection practice of bridges. In the end, critical crack lengths of hinge joint were determined based on a criterion of the "Single Plate Load Effect", that is, the critical crack length of single-side crack is 100 % of the total span length of the bridge, while that of the two-side cracks is 67%. This result will lead to further research on the failure mechanics of prefabricated hollow core concrete slab beam bridges and their retrofit techniques.
以都汶公路映秀-草坡段为研究区,选择了公路沿线15条典型泥石流沟进行了野外考察、遥感监测、试验研究和计算分析,采用部分泥石流参数计算经验公式并结合大比例尺数字地面模型和高精度遥感数据,初步建立了泥石流淤埋厚度、淤埋宽度和淤埋强度评估模型,进行了泥石流淤埋强度评估分析,并应用于都汶公路恢复重建和防灾减灾。结果表明:研究区段极高、高、中等和一般淤埋强度的泥石流沟分别为8条、1条、5条、1条,各占总数的53.3%、6.7%、33.3%和6.7%,总体呈强烈淤积趋势;8条泥石流的淤埋厚度可能达6~20 m、淤埋宽度可能达111~421 m,具有极高侵蚀产沙和冲淤能力,对流域内及沟口重大工程危害严重;对比分析红椿沟泥石流淤埋厚度与宽度的计算值与实测值可知所建立的评估模型具有较高精度和一定的实用性;评估模型中一些参数来源于经验公式,需要在进一步加强泥石流野外监测和试验研究的基础上,通过实测或试验分析获取,并修正相关经验公式,以满足震后泥石流评估工作需要。
The effect of friction at movable supports on the elasto-plastic seismic responses of continuous girder bridges was analyzed on the basis of three aspects including stiffness contribution, friction energy dissipation of the movable supports, and kinetic interaction between the girders and movable piers. Finite element models were established, which considered the friction nonlinearity of the movable supports and the material nonlinearity of the reinforced concrete piers. In addition, nonlinear time history analysis was performed to analyze the effects of friction at the movable supports on the pier bottom curvature, girder displacement, velocity, and acceleration. The results indicated that the frictional effect at movable supports is not always favorable. In some cases, the friction at these points must be considered. For the nonlinear time history analysis, the effect of natural vibration characteristics of the bridge and the response spectrum of the ground should also be considered. For some complicated continuous bridges, particularly those with the heights and stiffness of the fixed and movable piers, the friction at movable supports should be considered in seismic analysis.
粉质黏土属冻胀敏感性土,为了研究其冻胀率随含水率、压实度和冻结温度3个因素的变化规律,对取自黑龙江省境内哈大二级公路的粉质黏土进行了闭式冻胀模拟试验。分析结果表明:闭式冻胀单因素条件下,粉质黏土冻胀率与3个因素分别呈现一定的相关关系,低冻结温度、高含水率以及高压实度会加剧土体冻胀;含水率对冻胀率的影响最大,压实度次之,冻结温度最小;粉质黏土的起始冻胀含水率ω0=0.89ωp,临界冻胀含水率ωc=0.97ωp。此外,在冻胀试验结果的基础上,还应用SPSS统计软件建立了冻胀率为因变量,含水率、压实度和冻结温度为自变量的多元回归模型,模型可以用于粉质黏土的冻胀率预测。
When the two excavation faces of a tunnel constructed from both the entrance and exit simultaneously in soft surrounding rock approach, the excavation surface disturbance areas are superimposed,stress and deformation in the surrounding rock become extraordinarily complex, which results in substantial deformation and instability. By combining the study of the surrounding rock stress and displacement caused by both unidirectional and face-to-face excavation in the Shizilong Tunnel, the stability of the tunnel face with two excavation faces approaching one another in a bidirectional construction is analyzed by numerical analysis. It is shown that, with the reduction in the length of the unexcavated soil between the two excavation faces, the plastic zone and deformation significantly increase, and the arching effect gradually weaken, resulting in greatly reduced tunnel stability. When the distance between the two excavation faces is less than the limiting distance, an extended range of the surrounding rock approaches plastic failure, and only effective countermeasures can guarantee the safety of the tunnel construction. Further, bamboo anchor pipe grouting is adopted to reinforce tunnel faces with the initial support strengthened, when those two excavation faces in the construction of the Shizilong Tunnel are approaching. Field implementation indicates that the tunnel is excavated safely.
以距2008年攀枝花6.1级地震震中约9.7 km的攀田高速公路望江岭隧道田房端出口斜坡堆积体为研究对象,在连续的现场测斜监测数据的基础上,探讨了地震前、后斜坡堆积体的变形特性及其随时间的演进规律。结果表明:各测孔同震顺坡向位移最大值为26~28 mm,并沿深度近似呈逐渐减小分布;J3、J5测孔附近岩土体时效变形于震后约300 d达到峰值,而后逐渐稳定;至震后约430 d,由于坡体内、外界综合因素影响,J1孔顺坡向位移仍处于调整状态。综合现场监测成果,可以认为,在经历了大约1 a的自适应调整,特别是经2009年雨季后,斜坡堆积体已处于整体稳定状态。
To protect the environment and to minimize the water pressure on a tunnel lining, the controlled drainage principle is proposed for deep mountain tunnels below high water tables. The mechanical characteristics of tunnel supports and linings with respect to seepage and pressure are studied by using numerical methods and a test model based on the tunnel mechanics and seepage mechanics. The results show that the pressure exerted on primary supports is unrelated to surrounding drainage conditions. The pore water pressure on primary supports diverts to tunnel linings when the drainage system moves from the interface between rock mass and primary supports to the interface between primary supports and tunnel linings, and the primary supports are unloaded and the pressure moves outwards to the rock mass. The water pressure on tunnel linings can be neglected if the ground water can be discharged smoothly. When a tunnel drainage system malfunctions and leads to poor drainage, the flow gradient in the ground decreases, the effective radial stresses decrease, the radial flow of tunnel decreases and the ground deformations decrease.
采用有限单元方法,建立了开启桥钢桥面铺装体系复合结构模型,计算了在通车运营及通航开启2种状态下的铺装层应力,并通过室内试验测试了完全固化和室温自然养生等2种养生条件下的复合结构层间剪切强度。研究结果表明,开启状态下的铺装层与钢板之间层间剪应力增加幅度明显大于通车运营条件下的计算结果,开启桥钢桥面适宜采用厚度为30~40 mm的沥青混和料铺装层;通车运营及通航开启2种工况下的铺装层与钢板之间层间剪应力随着铺装模量的增加都呈明显上升趋势,建议铺装层施工应在高温条件下进行,通车及开启前的养护阶段都应保持高温条件。
To evaluate the performance of a traffic signal control system quickly and efficiently, a hardware-in-the-loop simulation system of multi-intersection traffic signal is developed. With the hardware-in-the-loop approach, a simulation model based on the microscopic traffic simulation software is established, and the real-time communication between the simulation software and the traffic signal controllers is achieved, altogether providing a realistic traffic control simulation environment to evaluate the performance of a multi-intersection traffic signal control system. A case study of Zhongguancun East Road along with the corresponding simulation results demonstrates that the hardware-in-the-loop system can evaluate not only the performance of various signal controllers, but also the performance of the traffic signal control system for multi-intersections quickly and efficiently.
在桩顶荷载施加之前,桩身往往已经存在残余应力。分析了卸载后桩身残余应力产生的机理、残余应力的分布规律及影响因素,并与负摩阻力桩基进行了对比分析。跟踪测试了一根单桩在竖向抗压静载试验卸载之后桩身应力和变形的分布情况。结果表明:卸载后,残余应力在桩身的分布类似负摩阻力作用的桩基,是桩周土体约束桩体充分回弹的结果,相当于桩周土体对桩施加了预应力;残余应力引起的侧摩阻力比负摩阻力小,残余应力不会引起桩基沉降发生变化。残余应力跟桩的尺寸、桩土接触面刚度及桩周土体的性质密切相关。
The sharp variation of illumination at the entrance and exit of highway tunnels causes difficulty in the visual adaptation of drivers and may even lead to accidents. Therefore, ascertaining the light and dark adaption time is a basic task to promote the safety of tunnel transportation. Took 26 typical tunnels as experimental settings and used the IViewX HED Laptop eye tracker system, the light and dark adaption of drivers in highway tunnels had been experimentally investigated. The relation between pupil area and its variation velocity was presented based on many experimental data and the ratio k of the variation velocity to its critical variation velocity was used to evaluate the visual load in highway tunnels and thus ascertained the visual adaption time, whereby the relation between tunnel length and visual adaptation time was thus obtained. Experimental results indicated that the dark and light adaption time of tunnels was less than 23 s and 13 s for medium and long length tunnels, respectively.
波形钢腹板组合梁是一种新型的钢-混凝土组合结构,在国内外的箱梁桥中得到广泛应用。为了推广该结构在T梁中的应用,结合交通运输部40 m跨径预应力混凝土连续T梁桥上部结构通用设计图,提出了40 m跨径波形钢腹板连续组合T梁设计方案,并进行了详细的结构分析计算,得到了波形钢腹板组合T梁的关键技术和经济性指标,并在技术、施工、经济等多方面与传统预应力混凝土连续T梁进行了对比。结果表明:与混凝土T梁相比,波形钢腹板组合T梁具有较大的技术和经济优势,可以推广应用。组合T梁设计方案与分析结果可供桥梁技术人员在今后类似工程中采用,具有很好的借鉴和指导意义。
A single release method for four-leg roundabouts is proposed. To completely use the time and space resources of roundabouts from the aspects of adjacent entrances and T-type storage spaces of the circulating lane, two types of optimized single release signal control models for a four-leg roundabout are presented. The coordination of signal phase design on the two types of optimized control models is presented, the phase coordination calculation is described in detail, and the original cycle length model is improved. By comparing the delays of the two optimized signal control models, the applicable conditions for optimized signal control models are discussed. Finally, considering the Tanxi Road/Changhong Road Roundabout in Xiangcheng, Xiangyang, as an example, the effectiveness of the presented optimized control models is evaluated. Simulated results show that the traffic flow at this roundabout is improved when the optimization methods are applied.
钢-混凝土结合梁由钢梁、混凝土板和剪力连接件组合而成,这三者在结合梁受力过程中分别存在不同程度的剪切变形,导致钢梁和混凝土板界面之间的相对滑移效应。本文基于ANSYS有限元技术,对世界上首座3塔4跨地锚式悬索桥——武汉鹦鹉洲长江大桥建立三维空间有限元全桥模型,通过有限元模型拼接技术将标准节段的精细化模型嵌入鱼刺梁式的杆系模型中,研究最不利工况状态下标准节段中预制桥面板与钢主梁之间剪力键的滑移效应。计算结果表明:在设计的移动荷载下,鹦鹉洲大桥最大的单钉剪力值为20.6 kN,仅为其设计承载强度的34.3%,最大滑移量值为0.086 mm;在1.5倍设计移动荷载下,最大的单钉剪力值为27 kN,为其设计承载强度的44.9%,最大滑移量值为0.163 mm。鹦鹉洲大桥现有剪力连接栓钉工作性能良好,承载富余较大。
To realize real-time and reliable transportation path planning for improving the efficiency of a traveler in a highway transportation network, this paper presents a fast traveler demand clustering algorithm based on simulated annealing particle swarm optimization (SAPSO). First, we apply fast clustering according to the traveler demand obtained by a cooperative vehicle system, and then integrate the results with the planning destination target and traveling vehicle information to realize the optimized highway transportation path. Based on an experiment and comparison results, this method has better performance than two algorithms and has high effectiveness and should increase traveler satisfaction.
为提高高墩大跨连续刚构桥长期变形预测的精度,重点考虑徐变对结构长期变形的影响,并考虑影响徐变系数众因素的随机性,将响应面法引入到结构长期变形的预测中。试验抽样采用中心复合设计法,响应面模型采用不含交叉项的二次多项式。采用偏检验进行影响参数的显著性检验,将徐变系数表达式表达成各随机变量的显示函数,并对其进行蒙特卡罗抽样分析,然后将其代入有限元模型中得到一定置信区间下的长期变形值。牛角坪大桥主跨192m,按照上述方法对主跨跨中的变形进行计算,并和实测结果对比,二者吻合度较高,实现了提高高墩大跨连续刚构桥长期变形预测精度的目标。
This study aims to analyze the theory mechanism behind MFOZ(main functional areas zone) and investigates MFOZ's effect on high ways and transportation. This study adopts the classic theory of increasing returns to scale of regional economies, draws lessons from the experience of world cities' development presented in a World Bank paper, and deconstructs the theory mechanism behind MFOZ and its effect on highways and transportation. MFOZ is a big achievement in spatial planning and territorial development, as through increasing returns to scale, the economic zone will attain more agglomeration and improved area integration. Zones with social and ecological functions through public service equalization will realize regional coordinated development. To respond to MFOZ's requirements, the economic zone should develop and realize transportation integration, while in the limited development zone and prohibited zone, we should realize equal transport service.
建立了9艘代表性轮船的精细有限元计算模型,通过与刚性墙面的碰撞模拟计算,获得了不同吨位和不同撞击速度下共81条船撞力时间过程样本。为考虑船舶撞击力时间过程的随机性,对撞击力的持续时间和撞击力幅值进行了无量纲化处理,得到了无量纲撞击力时间过程。将无量纲时间在21个断面上进行了离散化,通过统计检验,确定各断面上的无量纲撞击力符合正态分布,并给出了各断面的均值与标准差,进而得到了撞击力时间过程的概率统计模型。根据所建立的撞击力概率统计模型,引用随机数的生成技术,给出了生成船撞力时间过程的人工方法,并将人工生成的船撞力时间过程样本与碰撞数值模拟结果进行了比较,验证了本文方法的统计合理性和实用性。
IEEE 802.11p, which is a fundamental protocol of dedicated short-range communication in intelligent transportation systems, is evaluated in this work. The relationship of IEEE 802.11p with other protocols in the layered architecture for DSRC, as well as the standard framing process for wireless transmission, is studied. The common problems of the orthogonal frequency division multiplexing vehicular communication system and their solutions, such as channel estimation, carrier frequency offset, and symbol time offset, are analyzed by simulation. Analysis results indicate the acceptable reliability and performance of IEEE 802.11p. Simulation results confirm the viability of the design of related applications.
结合断裂群区内深埋碳酸盐岩隧道突水点的特征,从多条典型断裂群区构造形成环境、地层岩性、岩溶裂隙水边界条件结合隧道施工情况等因素,重点阐述了断裂群区岩溶突水灾害灾变机制。在此基础上建立断裂群区地层岩性、构造形迹、隧道埋深、水文环境、施工工法等6种致灾因子的风险评价模型。利用模糊层次分析法对断裂群隧道涌水风险、岩溶风险及施工安全风险进行评估,得出后二者风险较高。模糊优选出最适宜断裂群隧道岩溶风险物探方案,即TGP+GPR+炮孔加长法对隧址区隐患点进行了重点预测。与开挖揭露情况进行对比验证其准确性,并提出断裂群区岩溶突水的应急措施。最终形成断裂区隧道岩溶风险等级划分标准,以期对后续穿越断裂群隧道岩溶风险安全施工提供咨询。
To cope with the problem that less-than-truckload (LTL) logistics network design for certain origin-destination (OD) flow demands often fails to utilize the network resources in a balanced manner, the characteristics of OD flow uncertainties and network design difficulties are analyzed, and a mixed integer programming model is devised by considering the OD flow uncertainties based on inventory theory. An example study demonstrates that design of a logistics network with OD flow uncertainties based on optimizing the network operation and construction costs, and the network resources utilization ratio comprehensively has a significant improvement in balancing the utilization degree of network resources compared to only considering minimizing the network operation and construction costs. The result contributes to adjustment of the logistics network structure to improve the balancing utilization degree of network resources for uncertain OD flow demands.
由于网络设计决策的长期性,许多参数会随时间而变化,因此在交通运输网络设计问题中考虑不确定性因素至关重要。研究了在交通运输网络中边的容量有随机损失时的鲁棒性网络设计问题。边的容量损失是指实际运行时的可用容量小于初始设立的容量。假设容量损失是1个随机变量,首先建立了带有机会约束的鲁棒性交通运输网络设计模型,然后利用Hoeffding's不等式对机会约束进行了安全近似,将问题转化为一般的混合整数规划问题。鲁棒性模型使得当容量有波动时,网络仍以一定的概率正常运行。最后通过数值算例比较了单源和多源2种网络结构下网络设计的最优成本,并分析了成本与鲁棒性之间的关系,同时对容量的不确定性水平做了敏感性分析。
我国大城市交通非机动车流主要由普通自行车与电动自行车构成,二者具有异质性,主要体现在速度、横向位移意愿以及随机扰动引起的减速状态的差异,并具体表现为车辆影响域、横向位移倾向值、随机慢化概率的不同。采用多车道元胞自动机(Cellular Automata,CA)模型对混合非机动车流进行模拟研究。基于此分析了车辆构成比例对速度-密度、流量-密度及可实现的横向位移行为的影响。模拟结果显示:电动自行车的构成比例与前二者关系紧密;实现的横向位移数目,即横向位移率随密度的增长呈现先增后减趋势,且上升阶段会出现驻点,该点的产生表明低密度条件下出现了明显的偏析现象。
为了实现交通视频拥堵状态的自动识别,以满足日益广泛应用的交通视频监控需求,分析了交通拥堵评价模型及其定性过程,进而提出了一种具有自适应学习能力的交通视频拥堵信息识别方法。该方法系统提取视频图像特征集,应用SVM进行模型训练学习和状态分类,并采用GA进行算法模型的在线闭环自适应调优。现场试验表明,该方法具有识别准确率高、处理速度快和系统自适应能力强等优点,为解决全天候的基于视频的交通拥堵实时在线识别处理问题提供了一种快速有效的解决方法。
车辆跟踪中普遍存在车辆遮挡将直接影响事件检测精度的情况。为了解决这一问题,在介绍车辆跟踪算法基本原理的基础上,提出了一种基于视频与检测器数据组成的语义层次交通事件检测算法。该算法先应用时空马尔可夫随机场模型进行车辆跟踪,得到交通流基本参数,然后结合安装在道路下游的检测器获得的交通流数据一起,采用语义层次算法对交通事件进行检测。为了验证算法的准确性,最后对该算法与不使用检测器数据算法进行比较,发现使用检测器数据算法的检测率要高。通过研究得出:基于视频与检测器数据组成的语义层次算法在交通量比较拥挤且车辆出现相互遮挡的情况下,能准确判断交通事件发生,对缓解交通拥挤和减少交通事故有重要的意义。
隧道是城市交通的咽喉所在,为了有效引导隧道交通流,实现隧道交通状况的实时发布,从而引导驾驶员理性进出隧道,准确可靠的数据采集及实时交通流预测是关键所在。以VISSIM仿真为基础,建立研究隧道路网模型,以行程时间误差为依据,探讨了检测器在隧道中的空间合理布局,保证数据采集的可靠性。在准确的数据采集基础上,选取了自适应权重指数平滑法(AWES)以及基于径向基函数的神经网络模型(RBFN)进行实证研究,并采用数据融合技术以保障预测精度及误差的稳定性。并进一步以VISSIM仿真平台简略探讨了交通状态判别指标,以期更好服务于城市交通诱导系统。
研究高速公路协调控制信号施加策略问题。在STNS模型的基础上,建立可利用智能交通系统实时信息由一个入口匝道和一段主线组成的高速公路区段协调控制元胞自动机模型,对该区段实施不同控制信号策略的交通流特性进行了仿真。分析了不同的交通状态、主线上游流量和匝道需求下,分别实施不施加控制信号、仅施加匝道控制信号、仅施加可变速度限制信号、匝道控制和可变速度限制信号均施加4种方式对道路实际通行能力和交通流的影响。结果表明:协调控制作为高速公路管理控制的主要手段,具有较好的适用性,针对不同交通需求,分别采取不同的控制信号施加策略,可达到减少车辆总通行时间、抑制交通拥堵从而提高道路实际通行能力的目的。
雾霾天气下的高速公路监控视频质量降低,图像观感模糊,对比度和颜色等信息衰减,影响应用。而当前的视频增强算法难以在质量和实时性上取得平衡,针对这一情况,在充分分析大量的雾霾天气高速公路视频数据后,从雾霾天气对视频成像的影响原理出发,总结数据的特点,提出了一种快速的视频增强算法。算法自动判断雾霾浓度,对于低浓度的情况采用改进的限制对比度直方图均衡(CLAHE)算法,对于高浓度的情况则结合DOS和暗原色先验规律先进行帧图像的初步增强,然后通过自适应对比度调整进行局部重点增强。试验结果证明:该算法实时性高且增强效果较好;增加本文去雾霾算法模块后,虽然降低了系统运算速度,但提高了交通行为识别的正确率,使雾霾天气下高速智能监控系统的实用性得到增强。
运用重心分析方法考察了中国公路货物运输与制造业重心的空间分布和变化特征,探讨了二者间的相互关系。研究发现:我国公路货物运输重心表现为缓慢的南下东进特征,移动距离由剧烈走向缓和;与几何重心比较,公路货物运输和制造业空间分布一直处于不均衡状态,公路货物运输发展水平与制造业发展水平的区域差异总体上在扩大;与我国制造业重心变化轨迹相比,公路货物运输重心变化轨迹相似度较高,但公路货物运输重心变化具有先导性,且先导性程度日趋减弱,说明公路交通发展对制造业空间布局发展具有重要的影响作用,但随着公路交通的进一步发展,其引领与拉动作用逐渐减弱;公路货物运输和制造业区域差异受国家空间经济产业布局政策及由其导致的开放程度、开放时序的差别影响较大。
为了实现桥梁缆索缺陷的检测,针对桥梁缆索攀爬机器人进行研究,开发了一种适合桥梁缆索缺陷自动检测,具有强攀爬能力和高机动性的攀爬蛇形机器人。它由具有单自由度的模块组成,可根据缆索特征灵活增减模块数量实现手动重构。模块中的超大扭矩舵机、轻质铝合金机械构件和高摩擦系数的外皮等,增强了机器人的攀爬能力。模块正交连接与P-R连接结合应用,使得机器人可有效完成缆索攀爬运动和检测作业。设计一种主从分布式多级闭环运动控制系统,引入电池供电和扭矩限制,增强了机器人的机动性和对环境的适应能力。缆索模拟攀爬试验结果证明机器人具有很强的机动性和攀爬能力。
