In order to meet the diverse needs of pavement engineering for green, durability and functional improvement, in recent years, the application of polyurethane mixture in pavement engineering has received extensive attention. Through investigating the current research status of polyurethane mixture, this paper focuses on summarizing the research result in the field of water stability, while presenting the problems of current research and proposing feasible research directions. The results show that: polyurethane has greatly improved the road performance of asphalt mixtures. The water stability of polyurethane mixture is generally poor, but there is still lack of research on water damage mechanism of polyurethane mixture. The lack of water stability is the key problem restricting the application of polyurethane mixture.

Using UDEC discrete element method (DEM) and field monitoring method, the influence rules of slope height, slope angle and excavation stage on the stress field, displacement field and stability safety factor of high steep slope during excavation process were investigated. Research shows that: (1) The slope displacement and maximum principal stress gradually decrease and increase from the face (top) to the bottom of slope and from the middle (lower) part of the final excavation face to both sides of slope respectively, and the maximum displacement and stress increase and decrease with the increase of slope height (angle) respectively (decrease and basically remain unchanged with the increase of excavation stages respectively). (2) The curve of slope shoulder (top) displacement versus excavation times can be roughly divided into three development stages, i.e., the early stage of steep increase, the middle stage of gradual increase and the later stage of gentle decline (slope shoulder), gentle decline-steep increase or steep drop-slow increase (slope top). (3) Under the same slope height (angle) or excavation stages, the safety factor of slope stability first increases and then decreases with the increase of excavation times, and it decreases with the increase of slope height (angle) under the same excavation times (increases with the increase of excavation stages). (4) The results of numerical simulation reveal the real-time stress and deformation state of high steep slope in the process of multi-stage excavation, which is in good agreement with the field monitoring results. It is suggested that dynamic information design, construction and monitoring should be adopted for multi-stage high steep slope excavation engineering.

Aiming at the problem of the corrosion law of the suspension bridge main cable steel wire under status of holding force, a set of electrolytic accelerated corrosion test device with preload was designed. The electrolytic accelerated corrosion test of the main cable steel wire of the suspension bridge in the state of holding force suspension bridge main cable steel wire under status of holding force was carried out. A total of 60 steel wires with diameter 5.25mm were selected under four working conditions of 0, 1000, 2000 and 3000με. The quality and diameter of steel wire after 0-4 days of electrolysis accelerated corrosion were measured. Also the change law of the average mass loss rate and cross-sectional loss rate of the main cable steel wire with strain and time growth was discussed. The results of the tests showed that with the increase of strain level and corrosion time, the corrosion of steel wire under the stress state is more obvious, the fluctuation of local characterization is more intense, and the corrosion presents a nonlinear growth trend. The mass loss of the steel wire with 3000 με after four days of accelerated electrolytic corrosion is similar to the 420 days test result of natural corrosion, and the change trend is consistent. Under accelerated corrosion conditions, the average mass loss rate of steel wire with 3000 με after four days of accelerated electrolytic corrosion is 6.40 times that of one day. At the same time, the average mass loss rate of steel wire with 3 000 με after one to four days of accelerated electrolytic corrosion are 1.17 times, 1.22 times, 2.27 times and 3.02 times than 2000 με respectively. The maximum section loss rate increases with the increase of strain and time, and it has a good correlation with the two variables. Therefore, the maximum section loss rate can be considered as the core intermediate variable to measure the corrosion grade of main cable steel wire.

In order to improve the spatial stiffness of the super long-span bridge structure, this paper introduces the three-dimensional cable network into the super long-span bridge design, and carries out the configuration research of the three-dimensional cable network bridge. The introduction of three-dimensional cable network design elements can improve the landscape of the super long-span bridge and the cultural connotation of the super long-span bridge. The three-dimensional cable network can greatly improve the lateral stiffness and torsional stiffness of the super long-span bridge, and enhance the wind stability of the super long-span bridge. The use of three-dimensional cable net technology measures is conducive to breaking through the technical bottleneck of super long-span bridges, and can provide reference for similar bridge design in the future.

In this paper, the combined tower structure system of the super long-span curved cable-stayed bridge is composed of the univalent hyperboloid bridge tower, the bowl shaped thin-wall shell podium and the circular sightseeing platform plate. The sightseeing tower and the cable-stayed bridge tower in the scenic spot are two in one. The sightseeing tower improves the vertical stiffness of the super long-span pedestrian landscape curved cable-stayed bridge. The bowl shaped thin-walled shell podium can effectively limit the torsional deformation of the curved cable-stayed bridge deck. Combination 2×150m curved cable-stayed bridge, Midas finite element model is established to verify the scientific rationality of the super long-span pedestrian landscape curved cable-stayed bridge with sightseeing tower.

The deformation of primary support is one of the difficult problems often encountered in the excavation of deep lying soft rock tunnel. Be directed against the problems of the large deformation of primary support, the cracking of lining and the sinking of vault in Kalumoqi tunnel that is being built, the classification of surrounding rock and deformation monitoring are carried out, and the causes of the disease are analyzed.On this basis, the measures for changing the supporting parameters are proposed. The finite element software is used to verify the supporting effect of the changed parameters by numerical simulation, and the construction effect is evaluated by on-site monitoring. The results show that: (1) the part of vault is peeling and cracking phenomenon of sprayed concrete when disease occurs, and deformation of parts has obviously sustained growth, the deformation velocity value is larger, longitudinal connecting steel bar and steel arch shelf of primary support has appeared strong tensile deformation, steel arch shelf of primary support at the arch foot has broken, and the deformation of the primary support of the tunnel is larger, it shows a extruded deformation as a whole. The convergence value and rate at the arch foot are greater than those at the arch top, and the maximum convergence value of the arch foot is 50 mm, and the maximum convergence rate is 29 mm/d. The convergence of the arch foot has a sudden change, and the deformation shows a trend of continuous increase.(2) The numerical simulation results show that the displacement of subsidence of the sinking of vault, the arch waist and the arch foot decreases by 80%, 90.8% and 96.2%, respectively, compared with the original support parameters. The changed SVa support parameters produce less displacement deformation, and the deformation at the vault, the arch waist and the arch foot all meet the requirements of the design code,it can ensure the safety of tunnel construction and the stability of the structure. (3) By comparing the numerical simulation with the field that measured data after the parameter changes, it is found that sinking of vault, the convergence of the arch waist and the displacement of the arch foot is significantly reduced, the problem of the large deformation of the primary support is solved, the overall deformation of the surrounding rock tends to be stable, and the shape of all the supporting forms of the tunnel is intact without obvious damage phenomenon.

Transportation infrastructure is difficult to manage and maintain during the operation period, because they are widely distributed and involves many points. In view of this problem, the current situation of structural health monitoring of transportation infrastructure is introduced, a monitoring system architecture of regional transportation infrastructure group is proposed, the functional requirements of the platform is analyzed, and the key technologies such as data volume estimation, data flow control, structured storage, automatic operation and maintenance are studied. On this basis, Wuyuan Highway Integrated Platform is designed to realize the integrated monitoring of bridge and slope group in Wuyuan County. The application results show that the platform has complete and practical function, stable performance and reliable operation, which reduces the difficulty of management and maintenance of regional transportation infrastructure and improves the work efficiency.

The plane interchange adopts the form and traffic organization mode of alfalfa leaf interchange, that is, by adding right turn ramps and small loops on the 4 corners of the ordinary grade intersection, it is similar to alfalfa leaf interchange in form. Because of its low engineering cost, flexible traffic organization, simple control mode and high traffic efficiency, it has become one of the selection types of urban expressway and main road or main road and main road intersection. According to the geometric characteristics and traffic organization characteristics of plane interchange, and the evaluation objectives of intersection operation efficiency, safety, environment and other aspects, an index system based on 5 specific evaluation indicators is proposed, including traffic capacity, average vehicle delay, intersection safety, CO emission, and detour distance. To overcome the subjective or objective situation of the index weight in the process of multi index evaluation, the TOPSIS method is optimized by using combined weighting, and the traffic organization evaluation model of plane interchange based on combined weighting TOPSIS method is constructed. Taking the 3 traffic organization modes of the West Middle Ring Auxiliary Road and Xinghua West Street plane interchange in Taiyuan as an example, in continuous working days, traffic data are obtained through intersection flow direction investigation, point sample delay investigation, headway and speed investigation, VISSIM intersection simulation model is established, and the evaluation index values are obtained directly or indirectly. The advantages and disadvantages of various schemes are determined through the combined weighting-TOPSIS method proposed in this paper. The calculation results are compared with the actual situation, which verifies the rationality of the method. The result can provide theoretical support for the rational evaluation of the urban plane interchange traffic organization or the regional traffic organization scheme using this idea.

In order to solve the problem that parking space is hard to find in expressway service area, and provide accurate parking space information and effective parking guidance, a strategy of parking space occupancy recognition based on MobileNet and intelligent parking guidance is proposed. On the basis of detailed analysis of parking status and existing problems in expressway service area, this paper puts forward the classification strategy of intelligent parking guidance in service area, and builds the technical route of parking space recognition based on AI vision. Firstly, taking the high-grade video and low-grade video in the service area as the detection data sources, the lightweight MobileNet classification model is used to analyze the parking space occupancy in real time, so as to provide accurate and reliable information of the spare and occupied parking space in the parking area; Secondly, through the three-grade guidance screen, the three-grade parking guidance of main line preview guidance, entrance total capacity guidance and parking space guidance by vehicle type is realized, so that travelers can have a comprehensive understanding of parking space occupancy in the service area in advance. In order to verify the effectiveness of intelligent parking guidance classification strategy, a highway service area in North China is selected for field verification. The results show that the recognition accuracy of parking space occupancy recognition model based on MobileNet is 98.0% under sufficient illumination during the day and 90.0% at night; During peak holidays, the total travel time of vehicles due to congestion and waiting in service areas is reduced by about 7%, which can save 20% ~ 30% of the time for finding parking spaces compared with the time for finding parking spaces in traditional service areas. Therefore, the proposed parking space occupancy recognition based on MobileNet and intelligent parking guidance strategy can significantly improve the practical problems in the service area, meet the parking demand of the public to the maximum extent, relieve the parking pressure during peak hours, and improve the traffic capacity of the service area.

In order to study the influence of road geometric parameters such as curve, super-elevation and slope on the longitudinal and lateral coordinated control of intelligent and connected platoon, a cooperative control system using the longitudinal velocity of the vehicle as the coupled variable of the longitudinal and lateral motion is designed. The upper acceleration model of longitudinal car-following control adopted the improved intelligent driver model to reflect the influence of road geometric parameters on the car-following behavior. Combined with the inverse longitudinal dynamics model to realize the speed following of the guided vehicle. The lateral trajectory control adopted the single-point preview model in which the preview distance follows the coupling speed change to realize the trajectory tracking of the guided vehicle, and the sliding mode controller is designed to improve trajectory tracking accuracy. The Carsim/Simulink co-simulation platform was built, then acceleration-deceleration, double shifting line and ramp conditions were adopted to verify longitudinal, lateral and cooperative control performance of the cooperative control system. The results show that (1) The longitudinal and lateral cooperative control system has good longitudinal car-following performance and high lateral trajectory tracking accuracy, it maintains high tracking accuracy for the speed and acceleration of the guided vehicle. The distance between vehicles is positively correlated with speed changes, and the inter-vehicle distance tends to be stable when the speed is stable. Meanwhile, the steering angle of the control system has a high consistency with the Carsim's built-in model, and the steering is smooth. The lateral offset is less than 0.2 meters, and the control system with sliding mode control has higher trajectory tracking accuracy. (2) The intelligent and connected platoon composed of the coordinated control system based on the IIDM has more obvious longitudinal and lateral response to the road geometric parameters than the platoon of the IDM. The specific performance is that the deceleration behavior is more obvious, the inter-vehicle distance increase by 0.55 meters, the steering angle reduce and average lateral offsets reduce by 2.51×10^-6 meters, which is more conducive to the overall safety of the platoon.

The co-agglomeration between manufacturing industry and logistics industry is the main spatial manifestation of the coordinated linkage and integrated development of the two industries, and it is also a standard to test whether the linkage and integrated development of the two industries is effective. In the traditional new economic geography model, when the logistics cost is exogenous, the description of the formation conditions of the two industries' co-agglomeration is vague and difficult to quantify. The logistics sector is introduced into the agglomeration model as an independent sector, by establishing the linkage relationship between the average variable cost of logistics industry and the degree of agglomeration of manufacturing industry through industrial correlation, the endogenous treatment of logistics cost is realized; According to the degree of regional manufacturing agglomeration and the possible forms of two industry agglomeration, the average variable cost of logistics enterprises is solved, and the formation and evolution conditions of co-agglomeration of logistics industry and manufacturing industry under the condition of endogenous logistics cost are obtained. Through theoretical derivation and numerical simulation, it is found that the formation of co-agglomeration of manufacturing and logistics industry in a region is affected by two thresholds of logistics average variable costs, and the higher the degree of agglomeration of manufacturing industry in the region, the greater the interval width of two thresholds for complementary agglomeration and the smaller interval width of two thresholds for extruding agglomeration; when the logistics average variable costs is in the range between two thresholds, the degree of manufacturing and logistics industrial co-agglomeration is being U-shaped relationship with the manufacturing agglomeration, otherwise inverted U-shaped relationship. This study is helpful to grasp the general rules of the formation and evolution of the co-agglomeration of manufacturing and logistics industry. It provides theoretical support for promoting the deep integration of the two industries, ensuring the stability of the industrial chain and supply chain and high-quality economic development.

This paper constructs a profit function based on statistical data for each charging pile, and takes the shortest payback period as the objective function of charging pile location optimization, thus forming a charging pile location optimization model. The solution of the optimization model is transformed into the problem of searching the zero point of profit function by dichotomy. This provides a data-based decision-making for investors to invest in charging piles. At the same time, it provides a convenient service environment for electric vehicle users, improves the competitiveness of new energy electric vehicles, speeds up fuel substitution, reduces exhaust emissions of fuel vehicles, and prevents air pollution.