Abstract:With the increase in the cost of single vehicle intelligence and the increasing complexity of road environments， the development of smart driving vehicles is increasingly relying on the progress of smart road infrastructure. At present， in different road engineering construction projects both domestically and internationally， unique design ideas and functional modules are proposed for the intelligence of road infrastructure. However， relevant research mainly focuses on a single road function or specific technology， and there is no systematic proposal for the design theory and application system of smart road infrastructure. At the same time， the smart road infrastructure construction requires the development of roadside equipment， pavement materials， and external perception equipment in all directions towards informatization， digitization， and intelligence. Based on a systematic review of typical cases of smart road projects both domestically and internationally， four key technologies for future smart road facilities are proposed in this paper.

Abstract:This paper presents a method for sensing vehicle axle loads using distributed vibration fiber sensors to detect pavement vibrations. A mapping relationship between fiber optic signals and pavement vibration displacements is established， and analytical models for vehicle axle load inversion are proposed. Full-scale experiments are conducted to validate the accuracy of the proposed vehicle axle load inversion analytical models， while natural vehicle weighing tests are performed to verify the effectiveness of the vehicle axle load perception algorithm. The results demonstrate that the vehicle axle load sensing system， based on the inversion analytical models， achieves a maximum estimation error of 0.98% for individual axle loads and a total weight prediction accuracy of 0.34%. These accuracies meet the national standards of 2% for single axle loads and 5% for total weight. Furthermore， the system accuracy remains unaffected by variations in vehicle speed.

Abstract:A road marking segmentation algorithm based on object detection and iterative threshold segmentation was proposed. The BiFormer-improved YOLOv5 was adopted to locate road markings and obtain image patches. Then， the iterative threshold segmentation was used to capture the accurate region of road markings. Finally， the extracted road markings were evaluated for visibility based on Weber contrast. The results show that the proposed method can extract road markings rapidly and accurately， and effectively evaluate the road marking visibility.

Abstract:A modified LuGre friction model was established and used to calculate the critical hydroplaning velocity， which is an indicator for determining the occurrence of hydroplaning events. Based on the water film thickness distribution and the probabilistic model of speed and wheel track， the probability of hydroplaning events was calculated to quantify the risk of hydroplaning， and the hydroplaning risk was set to five levels according to the probability. Results show that the critical hydroplaning velocity is significantly affected by the water film thickness， and related to the elevation of road sections. The critical hydroplaning velocity decreases in the disease area. The distribution of vehicle hydroplaning risk and critical hydroplaning velocity is basically the same， but the vehicle hydroplaning risk in the wheel track zone is relatively high. Meanwhile， at high rainfall intensity， more than 96% of disease-free or low-disease road sections are at low hydroplaning risk. However， in potholes， ruts and other road disease areas， the hydroplaning risk increases significantly， and high-risk areas appear， resulting in an increase of the road risk level.

Abstract:A pavement roughness prediction model based on encoder-decoder structure was proposed， and a comparative analysis of different layers was conducted. Then， the effect of the layer number， the number of hidden units and the time window length on the accuracy of the model was discussed. To train and evaluate the model， an international roughness index （IRI） dataset was constructed based on long-term pavement performance （LTPP） database published by the US Department of Transportation. The results show that the encoder-decoder structure with gated recurrent unit （GRU） layer has the highest accuracy， its performance is better than that of the machine learning model XGBoost and single long short-term memory （LSTM） network. The importance of different input features was evaluated by randomly shuffling features， and the results indicate that the road structure and temperature are important for pavement roughness prediction. Therefore， the road structure and temperature data should be attached great importance during the construction of pavement database.

Abstract:In order to improve the energy utilization efficiency of electroosmotic drainage in over-wet subgrade， electroosmotic drainage laboratory tests with different loading methods and potential gradients were carried out， and the evolution characteristics of energy consumption coefficient and instantaneous energy consumption coefficient with time and water content were analyzed. Finally， a stepwise loading method with low energy consumption was proposed. The results show that the energy consumption coefficient initially declines and subsequently increases in electroosmotic drainage tests. The negative correlation between the loading potential gradient with the lowest instantaneous energy consumption coefficient and the average moisture content can be expressed by power function. The low energy consumption stepwise loading mode based on the power function can save 54% energy compared with the stable voltage loading at 1.2 V?cm^-1 and 23% energy compared with the traditional stepwise loading.

Abstract:In order to study the axial compression capacity of the aluminum alloy square tube with initial bending， the axial compression stability test of 8 specimens was completed， and a finite element model with the same test conditions was established. The reliability of the finite element model was verified by comparing the results of experiments and finite element analysis. The results show that the failure mode of the aluminum alloy square tube with large initial bending is the overall bending instability. Finally， according to the finite element analysis results， the calculation formula of the overall stability coefficient of the aluminum alloy square tube with large initial bending was obtained， and by comparing results of the fitting calculation formula with the numerical analysis results and the test results， the correctness of the calculation formula was verified.

Abstract:Eccentric tension tests on C50 concrete composite deck and steel fiber reinforced concrete (SFRC） composite deck specimens， together with corresponding finite element simulations based on the plastic damage model of materials were executed to investigate the axial tensile stiffness reduction and cracking characteristics of the composite deck. Furthermore， segment finite element models of continuous steel box girders with SFRC composite deck were established for parameter analysis to explore the effects of concrete material， SFRC slab thickness and reinforcement ratio on mechanical properties of main girders. The test and numerical analysis results show that the SFRC slab appears more cracks but the crack widths are much smaller. When the crack width reaches 0.10 mm and 0.20 mm， respectively， the residual contribution of the SFRC slab to the axial tensile stiffness of the composite deck is 44% and 23%， while that of the C50 slab is only 12% and 9%， indicating that SFRC slab still has a great contribution to the mechanical performance of the composite deck after cracking. The parameter analysis results show that the residual contribution of the SFRC slab to the bending stiffness of main girders is about twice that of the C50 slab at the corresponding load level with the SFRC slab crack width of 0.10 mm. When the crack width of the SFRC slab reaches 0.10 mm， the bending stiffness of main girders with 80~120 mm thick SFRC slab decreases by about 11% compared with the uncracked state. Moreover， increasing the reinforcement ratio of the SFRC slab can improve the damage degree， but it has little effect on improving the bending stiffness of main girders.

Abstract:In order to explore the fatigue cracking mechanism and strengthening methods of U-rib butt welds in steel bridge decks， a total of two full-scale single U-rib specimen models with embedded sections were designed， and the fatigue failure modes and actual fatigue resistance of the detail were investigated through model tests. Then， based on the linear elastic fracture mechanics method， a butt-weld cracked model repaired by CFRP strips was established， and the effects of the number of layers and the size of CFRP cloth on the fatigue performance were investigated through numerical simulation. Finally， the non-destructive repair methods and construction process of pasting CFRP strips were introduced for the U-rib butt welds， and the fatigue test of the cracked specimens repaired by CFRP strips was carried out. The results indicate that the fatigue vulnerable points of the U-rib butt welds all appear at the arc transition of U-rib， and the average fatigue strength is only 59.7 MPa. After being repaired by three layers of CFRP strips， the fatigue strength of the welds with different damage degrees is about 0.8 to 2.6 times of unrepaired specimens. Pasting CFRP strips can effectively improve the fatigue performance of the U-rib butt weld details of the steel bridge decks， and meet the demand for the non-destructive repair of actual bridges.

Abstract:In order to study the influencing factors and direct shear performance of precast segmental bridge piers with splice sleeve， direct shear tests were conducted on precast segmental bridge piers with additional shear keys and different splice sleeve position. Then， the damage development and failure mode of models were analyzed. Finally， the shear mechanism of precast segmental bridge piers was discussed and the test results was compared with the calculated results of the existing shear formula. The results show that there are two failure modes in the direct shear test of low piers， namely， the failure mainly due to the development of diagonal cracks and the failure mainly due to the slippage of the splicing joint； the setting of the sleeve at the bottom of the pier will change the failure mode of the pier. As a result， the failure of the specimen is dominated by the slip of the splicing joint； the shear formula in GB50010―2010 can reasonably predict the shear strength of the precast segmental bridge piers with splice sleeve.

Abstract:Based on a shield tunnel project that simultaneously crosses multiple piles and existing tunnels， a numerical model was built and verified. The laws of surface settlement， convergence of existing tunnels and pile deformation induced by shield tunneling were summarized via the simulation. In addition， the barrier effect of piles on the transmission of disturbance was highlighted. The pile-soil-tunnel interaction mechanism was also revealed with the analysis of stress path of soils. The results show that the existence of pile foundation reduces the surface settlement and the width of settlement trough induced by shield tunneling， and changes the deformation mode of the existing tunnels. All these differences indicate that the pile has obvious barrier effect on the transmission of disturbance. A large lateral displacement occurs at the top part of piles and the lateral inclination of the pile cap undergoes complex trends， which is the results of the existing tunnel and shield tunneling process. The stiffness difference among piles， tunnels and soils is the basic reason for pile-soil-tunnel interactions.

Abstract:In this paper， we investigate the inherent mechanism of the drainage effect of soft soil under air- injection pressurization through one-dimensional physical tests on the remolded soil. The experimental system includes pressurization devices， soft soil compaction （fracture） observation devices， drainage measurement devices， etc. Then， we observe the settlement of the soft soil， the drainage process， and the crack development characteristics. The results show that the pressure gas achieves the drainage compaction and fracturing of the soil by displacing the pore water and elastically expanding the pores. Combined with the obvious weak characteristics （or cracks） and the degree of surface soil compaction， the drainage enhancement mechanisms of soft soil under air injection pressurization can be divided into three types： drainage with fracturing， drainage with compaction， and drainage with permeability.

Abstract:The low-grade road driving data of 22 drivers were collected through driving simulation experiment， and the driving fluctuation index was proposed based on Lorenz scatter plot. Then， the instability fluctuation thresholds of tangential acceleration， lateral acceleration and steering wheel speed were obtained （0.993， 1.322 and 0.669 respectively）. Finally， the fuzzy logic theory was used to synthesize the three indicators to complete the classification of the safety state. It is found that the fluctuation of tangential and lateral acceleration is affected by the interaction of weather scene and curve radius， and the dangerous instability is most likely to occur on the 15 m curve in the icing section. However， the instability of steering wheel speed is only affected by the curve radius， and increases with the increase of curve radius.

Abstract:The inversion method of ballastless track performance degradation based on the multi-channel analysis of surface waves was proposed. Based on the theoretical surface wave dispersion curve， the dispersion characteristics of ballastless tracks with varying degrees of degradation were analyzed. A method for inverting the ballastless track performance degradation was constructed， and the effect of excitation frequency and detector placement mode on the inversion effect was studied. The results indicate that the shear wave velocity of CA mortar and track slabs respectively determines the surface wave dispersion curve of ballastless tracks at low and high frequencies. To enhance the inversion effect， the excitation frequency is recommended to be set at 50 kHz， the minimum offset distance should be greater than or equal to 0.05 m， and the channel spacing between tracks should be 0.05 m. Moreover， the length of the detector arrangement should be increased as much as possible.

Abstract:According to the constraints of the total vehicle travel time， vehicle load， and the soft time windows， we studied the stochastic travel-time vehicle routing problem with simultaneous pick-up and delivery （STT-VRPSPD） considering soft time windows and established a chance-constrained programming model. Combining the tabu search algorithm with the scatter search algorithm， a hybrid scatter tabu search （HSTS） algorithm was constructed， and the C-W saving algorithm was used to generate initial solutions. Based on the classic Dethloff instances and Solomon time window generation method， 20 groups of instances including 50 customers and 20 groups of instances including 200 customers were generated respectively for numerical tests. The numerical results verify the effectiveness of the HSTS algorithm.

Abstract:The pseudo potential two-phase lattice Boltzmann method （LBM） was used to study the fluid flow state of gas diffusion layers (GDL） for carbon paper and carbon cloth under non-humidification conditions. GDL samples were constructed by random method and X-ray scanning method. In order to verify the accuracy of surface tension and contact angle calculation in the modeling process， the glass bead model was adopted. By adjusting the hydrophobic and hydrophilic characteristics of GDL， the real-time state of fluid flow in pore structure was analyzed， and the effect of hydrophobic and hydrophilic characteristics on the distribution of the water saturation in the pore structure was obtained. The results show that the water distribution in hydrophobic GDL is significantly different from that in hydrophilic GDL. Better hydrophobicity is more conducive to the discharge of water in GDL. In addition， GDL with stronger hydrophobicity significantly increases the inlet pressure of liquid water entering GDL， which may make catalyst layer （CL） more vulnerable to water penetration.

Abstract:An algorithm based on machine vision for adjusting the illumination angle of headlights was established. The image sensor was used to collect road images， and then the image information was processed to extract the parameter information of the required road. Combined with the calculation model for adjusting the illumination angle of headlights in different scenarios， the illumination angle of headlights was adjusted in time to provide suitable lighting in real time for the vehicle driving at night when the road condition was about to change. The algorithm was tested in the actual road environment， and the results show that the algorithm can effectively solve the problem of the hysteresis of headlight deflection.

Abstract:Based on the fuzzy information and multi-attribute decision making， a failure mode and effect analysis （FMEA） method for shared electric vehicles（SEVs） was proposed， including determining experts candidate and their authority weights through mutual evaluation， constructing risk assessment criteria through qualitative analysis， testing expert opinions using consensus theory， objectively weighting risk factors using close degree optimization method， and ranking the risks of failure modes by introducing the combinative distance-based assessment （CODAS） method. The results show that high-risk failure modes are mainly distributed in power system and driving system. The robustness of the results and the validity of the method were verified by sensitivity analysis and comparative analysis. Finally， feasible safety management measures were proposed.