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16 July 2024, Volume 43 Issue 7 Previous Issue   
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Transportation Infrastructure Engineering
Transportation+Big Data & Artificial Intelligence
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Transportation Infrastructure Engineering

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Chloride Ion Erosion State and Microstructural Features of Box Beams of Jiaozhou Bay Bridge XIN Gongfeng1,2, YUAN Yangguang3, HAN Tao2,4, LI Fan1,2, HUANG Pingming5 2024, 43(7): 1-8.  DOI: 10.3969/j.issn.1674-0696.2024.07.01 Abstract ( )   PDF (4620KB) ( )   To understand the chloride ion erosion state and the microstructural features of box beams of Jiaozhou Bay Bridge in the current stage, sampling tests were conducted according to the supports of exposure test station of Jiaozhou Bay Bridge. Total chloride ion concentration and free chloride ion concentration were tested, and industrial CT scan was also completed. By fitting the chloride ion concentration curve of the exposed specimens, the chloride ion erosion state of box beams in the current stage was investigated. Based on historical test data, the surface chloride ion concentration and age decay coefficient under natural exposure conditions in high latitude northern sea areas were analyzed. Through the analysis of industrial CT scan data, the microscopic pore structure characteristics of box girder concrete at the current stage were studied, including pore distribution, porosity, pore dimension, etc. The research results find that in the current stage, the maximum chloride erosion depth of box beam of Jiaozhou Bay Bridge is around 14~28mm. The ratio of apparent chloride ion diffusion coefficient to effective chloride ion diffusion coefficient is 1.24~2.77. There is a big difference between the chloride ion binding performances of specimen in atmospheric area and splash area. The binding coefficients of chloride ion in atmospheric area increase gradually with the increase of the depth, and then tend to be stable. In the high latitude marine environment of the north, the evolution of surface chloride ion concentration in atmospheric and splash areas can be both described by logarithmic growth law. The age decay coefficient of chloride ion transport is 0.6129 for the box beams of Jiaozhou Bay Bridge. When in service for 13.7 years, the porosity of the box girder concrete of Jiaozhou Bay Bridge is 1.05%, and the equivalent pore diameter follows a lognormal distribution. The pore surface area and pore volume follow an exponential distribution. References | Related Articles | Metrics

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Experimental Study on Mechanical Properties Sensitivity of Porous Lightweight Concrete HUANG Feng1,2, LIU Xingchen1,2, ZHANG Ban1,2, ZHANG Ruilin1,2 2024, 43(7): 9-16.  DOI: 10.3969/j.issn.1674-0696.2024.07.02 Abstract ( )   PDF (7220KB) ( )   The commercially available composite foaming agent, 42.5# ordinary portland cement, sand of 80 mesh, grade-I flyash, and 15 mm polyvinyl alcohol fiber were selected. The basal mix ratio was obtained, which was mcement∶mflyash∶msand=1∶0.250∶0.375, and the water-binder ratio W was 0.35, the flyash-binder ratio F was 20%, the sand-binder ratio S was 0.3, the mass addition ratio of polyvinyl alcohol fiber f was 0.10%, the volume addition ratio of foam N was 2.0. Using the controlled single variable method, 12 sets of porous lightweight concrete specimens were prepared for comparative analysis by adjusting W = 0.40, 0.45, 0.50, 0.55, F = 15%, 10%, 5%, 0%, N = 1.5, 1.0, 0.5, and 0, respectively. The stage characteristics of the stress-strain curve and the variation law of mechanical parameters of porous lightweight concrete with different mix proportions were analyzed by uniaxial compression test. The response sensitivity law of peak strength σpeak and elastic modulus E of porous lightweight concrete under W-N, N-F, and W-F interaction effects was analyzed by multi-factor interaction response models. The results show that under uniaxial compression loading, the residual strength σre of porous lightweight concrete is about 70% of σpeak, showing the characteristic of “yield pressure and absorb energy”, and the significance of this characteristic increases with the increase of N. Under multi-factor interaction effects, the morphology of the response surface for peak strength σpeak and elastic modulus E is nearly same. The proportion of medium pores in porous lightweight concrete is about 18.37%, which is the largest. The “honeycomb-shape” pore structure can effectively transfer and disperse external loads. With the characteristic of “yield pressure and absorb energy”, the damage process of the microscopic pore structure of porous lightweight concrete includes two stages: distributed damage and local damage. References | Related Articles | Metrics

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Long and Narrow Deep Foundation Pit Deformation in Xian Collapsible Loess Region MEI Yuan1, 2, ZHANG Miaomiao1, 2, ZHOU Dongbo1, 2, ZHANG Yan1, 2 2024, 43(7): 17-25.  DOI: 10.3969/j.issn.1674-0696.2024.07.03 Abstract ( )   PDF (4813KB) ( )   In order to investigate the spatial and temporal evolution laws of pile lateral displacement and surface subsidence during the excavation of deep foundation pits in the metro stations in Xian area, a certain deep foundation pit of a metro station in Xian area was taken as the engineering background, meanwhile the measured data of 20 narrow and long foundation pits on Line 2, 3, and 4 in the above region were collected and statistically analyzed. The results show that the maximum lateral displacement δhm of the subway foundation pit enclosure structure is 0.04%H~0.10%H (H is the excavation depth), the average value is 0.06%H, and the maximum lateral displacement position depth is 0.7H. The maximum surface subsidence value δvm is within the range of 0.036%H~0.116%H, and the main influence area is within the range of 1.4H. Gaussian function model can predict the surface subsidence in Xian area, whose influence range is 3.5H. Within a specific range, increasing the stiffness and insertion ratio of the supporting pile can effectively control the foundation pit deformation. The research results can provide reference for the design and construction of foundation pit support structures for other subway stations in Xian. References | Related Articles | Metrics

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Slurry Dewatering Model Test with Combined Treatment of Flocculation-Vacuum Filtration-Geotextile Tube WU Haimin, YI Feng, ZHENG Honghui 2024, 43(7): 26-33.  DOI: 10.3969/j.issn.1674-0696.2024.07.04 Abstract ( )   PDF (7979KB) ( )   In recent years, geotextile tubes have been widely used in the dewatering treatment of dredging slurry in rivers and lakes because of their good drainage reverse filtration performance, but they have the problem of slow dewatering rate in the later stage of dehydration. Therefore, physical model tests were carried out to verify the feasibility of using a pressurized vacuum pump to increase the later dehydration and consolidation rate of mud inside the geotextile tubes under the condition of adding flocculants. Meanwhile, the filtration and dewatering efficiency of the “aerodynamic oscillation method” and the “tube top loading method” were also compared. The test results and analysis show that: the “aerodynamic oscillation method” will cause cracks in the originally relatively dense mud in the geotextile tube, so that the airtightness of the mud in the geotextile tube will be destroyed. The “tube top loading method” increases the pressure of the mud in the geotextile tube, which improves the pressure gradient on both sides of the reverse filtration layer, so as to increase the filtration speed of the dredging mud. Vacuum filtration can significantly reduce the mud moisture content inside the geotextile tube and around the filtration pipeline, and the closer the filtration pipeline is to the center of the geotextile tube, the higher the filtration efficiency and the lower the mud moisture content. References | Related Articles | Metrics

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Risk Assessment of Mountain Debris Flows Based on Improved Cloud Model and Linear Programming Optimization Algorithm LI Li1, NI Bo1, QIANG Yue1, WU Hengbin1, WANG Kui2, ZHAO Dongsheng1 2024, 43(7): 34-43.  DOI: 10.3969/j.issn.1674-0696.2024.07.05 Abstract ( )   PDF (3636KB) ( )   Debris flow, a geological disaster of great destructive power that often occurs in mountainous areas triggered by heavy rain or earthquakes, requires the utilization of specific algorithms to evaluate its hazard in order to prevent and reduce its destructive power in advance. The cloud model fog characteristics were used to conduct a consistency test and coupling of the weights of various evaluation indicators, obtaining a reasonable weight threshold interval. Linear programming optimization algorithm was then utilized to dynamically set the value of each evaluation indicator within the weight interval by setting the objective function, thus obtaining the most dangerous score for each debris flow channel. Furthermore, the cloud digital feature formula for a single indicator was improved to construct a comprehensive cloud model with more comprehensive coverage, and the maximum hazard score was inputted to classify the hazard level of debris flow channels in the study area. The proposed study was applied to 72 instances of debris flow channels in Beichuan County after the Wenchuan earthquake. It is indicated that the evaluation results are consistent with the actual topographical environment of the study area, providing new ideas for the prevention of similar types of debris flow disasters. References | Related Articles | Metrics

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A Quantitative Model of the Alertness Level on Mountain Roads Considering Human and Environmental Factors LIU Tong1, HU Hong1, SHAN Jue2, LIU Tangzhi1, LIU Xingliang1 2024, 43(7): 44-51.  DOI: 10.3969/j.issn.1674-0696.2024.07.06 Abstract ( )   PDF (3818KB) ( )   In order to describe the alertness state and level of highway drivers on mountain roads, a quantitative method for the alertness level on mountainous roads was proposed by comprehensively considering human and environmental factors. The initial observation indicators were determined by analyzing the drivers eye movement and behavior data, the dimensionality of multi-source data was reduced based on the kernel principal component analysis method, and the reduced principal components were classified into high and low alertness levels by using K-means clustering method. Taking the probability of low alertness level samples as the target variable, the alertness level quantitative factors were obtained by screening human and environmental factors. Based on the score card method, the quantitative model of the alertness level on mountain roads was established, which was verified through practical examples. The research results show that the AUC value and KS value of the quantitative model for the alertness level on mountainous roads considering human and environmental factors are 0.907 and 71.86%, respectively. The proposed model has good performance and can provide reference for the dynamic evaluation of alertness level of drivers on mountainous roads and the construction of safety supporting facilities. References | Related Articles | Metrics

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Modeling and Analysis of E-Bike Helmet Wearing Behavior Considering Urban-Rural Differences JING Peng, MING Baixu, WANG Daoge 2024, 43(7): 52-60.  DOI: 10.3969/j.issn.1674-0696.2024.07.07 Abstract ( )   PDF (1254KB) ( )   When E-bikes have become the main means of transportation for short distance travel for residents, their related traffic safety issues are becoming increasingly prominent. Wearing helmets correctly can reduce the risk of death in traffic accidents for cyclists. However, statistical data shows that nearly half of cyclists in China still do not wear helmets while riding, and the consequences of E-bikes accidents cannot be effectively controlled. Compared with the urban, the rural has a higher number of E-bikes, and due to rugged roads and imperfect traffic construction, the rural is more prone to road traffic accidents, especially when a large number of cyclists do not wear helmets. To clarify the heterogeneous mechanism of helmet-wearing behaviors between urban and rural riders, and to deeply analyze the deeper reasons why riders do not wear helmets, the difference test and binomial Logistic regression model were used to analyze the comprehensive effects of rider characteristics, individual helmet awareness, and the law enforcement environment on helmet-wearing behaviors of urban and rural riders. The research results show that compared to the group living in the urban for a long period of time, the rural group has a weak subjective safety awareness and is more concerned about the barriers (obstruction of vision, inconvenience, etc.) that exist when using helmets. In addition, urban groups are more sensitive to traffic police enforcement activities and people who travel longer in the city are more likely to wear helmets. However, for rural groups, the protective effectiveness and price of helmets are important factors that they consider when making decisions about helmet wearing behavior. The research results may help traffic police to conduct further safety education and enforcement activities to promote safe travelling with helmets for cyclists. References | Related Articles | Metrics

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Same-Side Continuous Entrance Spacing on Expressway Mainline Based on Cellular Automata ZHANG Hang1, PENG Xiang1, MA Baolin1, WANG Xingyue1, LYU Nengchao2 2024, 43(7): 61-69.  DOI: 10.3969/j.issn.1674-0696.2024.07.08 Abstract ( )   PDF (2694KB) ( )   In response to the issue of vehicle safety and traffic efficiency at continuous entrances on the same side of the mainline of expressways, a study was conducted on the spacing between continuous entrance on the same side of the mainline of expressways. By establishing a cellular automaton simulation model, the difference of design speed of the mainline and ramp was analyzed, and the effect of the length of the continuous entrance spacing between the mainline and ramp on traffic conflict rate, average number of congested vehicles, and average speed on highways was also analyzed. Recommended values of the spacing between continuous ramp entrances on the same side of the mainline under different combinations of mainline and ramp design speeds were proposed. Simulation comparative analysis was carried out on the operating conditions under different spacing combinations. The research findings indicate that when there is a significant difference in design speed of the mainline and ramp, the spacing between continuous entrances on the same side of expressways in current specifications fails to meet the requirements of traffic safety and operational efficiency. Compared to using the general values specified in regulations, the average speed of mainline vehicles increases from 81.39km/h to 95.29km/h, the collision rate of ramp vehicles decreases from 0.0335 times/(km·veh) to 0.025 6 times/(km·veh), and the average congestion of ramp vehicles decreases from 0.0077veh/s to 0.002 2 veh/s, when the recommended values proposed in the text are adopted. Thereby, the vehicle traffic efficiency is enhanced, and the risk of vehicle accidents is reduced. References | Related Articles | Metrics

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Application Research of Layout Optimization of Urban Agglomeration Expressway Network Based on ICAE Algorithm PEI Yulong, WEN Yuhang,WANG Wanjiao, PAN Sheng 2024, 43(7): 70-76.  DOI: 10.3969/j.issn.1674-0696.2024.07.09 Abstract ( )   PDF (5075KB) ( )   To improve the degree of expressway network accessibility and reachability level of urban agglomeration, the optimization model reflecting the characteristics of urban agglomeration was established and the imperial competition algorithm was improved to explore the optimization effect of the layout by taking the Ha-Chang urban agglomeration as a case study. Firstly, expressway travel time was used to determine the accessibility level of urban agglomeration, and the optimization model was established by considering accessibility, distance and other parameters. Then the evolution operator was introduced to improve the algorithm, and the imperial competition algorithm based on evolution (ICAE) was constructed. Finally, the constraints were determined and solved according to the characteristics of the Ha-Chang urban agglomeration, and the optimization scheme was determined by using the solved nodes and the surrounding road network. The study shows that: the improved algorithm improves convergence accuracy by 16.4%, reduces time by 42.4%, which solves a total of 6 nodes, plans to build 6 new expressways and renovates 14 expressways. After optimization, the coverage of 2h traffic circle of expressways in the urban agglomeration reaches 65.3% and the level of traffic circle of 14 counties rises. The proposed optimization scheme enlarges the scope of 2h traffic circle of the urban agglomeration. References | Related Articles | Metrics

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Analysis of Important Nodes of Urban Agglomeration Network from the Perspective of High-Speed Traffic Flow JIAO Liudan, ZHANG Xinyu, HUO Xiaosen, ZHANG Yu 2024, 43(7): 77-84.  DOI: 10.3969/j.issn.1674-0696.2024.07.10 Abstract ( )   PDF (1875KB) ( )   When the transportation capacity of some nodes in urban agglomeration decreases, it will have a greater impact on the overall network than other nodes, therefore, such nodes will be considered as important nodes. It is of great significance to ensure the normal operation of urban agglomeration, maintain the normal flow within urban agglomeration, and promote the high-quality development of urban agglomeration by identifying important nodes in urban agglomeration and strengthening the protection of important cities. The urban agglomeration network model was constructed from the dual perspectives of high-speed railway flow and expressway flow, and the important node evaluation model of urban agglomeration network was constructed from the urban correlation, clustering and intermediary by drawing on the gravitational model. The Chengdu-Chongqing economic circle was taken as an example for empirical analysis. The research results show that the overall importance of each node city decreases non-linearly in the high-speed railway network model, while the overall importance of each node city decreases linearly, and the decline is relatively uniform in the expressway network model. References | Related Articles | Metrics

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Passenger Flow Evolution and Route Diversion of Large-Scale Winter Events in Outer Suburbs QIN Huanmei, JIA Meiru, QIAN Cui, CAO Jing, CHEN Yanyan 2024, 43(7): 85-93.  DOI: 10.3969/j.issn.1674-0696.2024.07.11 Abstract ( )   PDF (4816KB) ( )   The effective passenger flow organization is the key to ensure the successful holding of the large-scale events. Based on the passenger flow characteristics and stated preference survey of the large-scale winter events, the route choice model for spectators and the dynamic evolution model of passenger flow were established. The dynamic variation law of passenger flow distribution and queuing time distribution at various facility nodes of large-scale events was analyzed. The research results show that increasing facilities such as heating rooms, souvenir shops and scenic spots will enhance the viewing experience of spectators in the large-scale winter events in the outer suburbs. Spectators acceptable psychological threshold of the queuing time for security check/ticket check or waiting time for public transport and the walking time to the venue is 20 minutes for the large-scale winter events. Moreover, spectators are more likely to choose the route with shorter walking time and more service facilities. Adopting route diversion and providing real-time route information can make the passenger flow distribution on the upstream and downstream nodes of the diversion path more balanced and smoother, which effectively reduces the passenger flow gathering and queuing phenomenon. References | Related Articles | Metrics

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Security Risk Assessment of Approach Control System Based on Two-Dimensional Cloud Model ZHANG Zhaoning, SHI Zhuochen 2024, 43(7): 94-103.  DOI: 10.3969/j.issn.1674-0696.2024.07.12 Abstract ( )   PDF (5075KB) ( )   The safe operation of the approach control system is essential to ensure the safety of civil aviation transportation. Safety risk assessment forms the foundation of risk management, enhancing the efficiency of safety risk management and overall operational safety of the system. Simultaneously considering safety risk factors and safety risk events, a safety risk assessment index system for approach control system was established from 5 aspects such as controller risk, equipment risk, meteorological environment risk, regulatory environment risk and management risk. By using a two-dimensional cloud model, the safety risk level of a certain approach control system was determined to be level III and compared with a one-dimensional cloud model, which proved the effectiveness of the proposed assessment model. The combination weighting method was compared with the improved analytic hierarchy process method and CRITIC method. The results show that the combination weighting method not only reduces subjective arbitrariness, but also neutralizes the shortcomings of subjective and objective weights. Therefore, using the combination weighting 2D cloud model for approach control system security risk assessment results is more accurate. References | Related Articles | Metrics

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Berth Resource Allocation for Multi-terminal Transit Ports Based on Multi-objective Optimization DING Yi1, TANG Ming1, CHEN Kaimin2 2024, 43(7): 104-111.  DOI: 10.3969/j.issn.1674-0696.2024.07.13 Abstract ( )   PDF (3699KB) ( )   Water-water transshipment of containers is an economical and efficient waterway transportation mode. To effectively reduce the inter-terminal transit cost of transshipment containers in large transshipment hub ports under water-water transshipment scenarios, a multi-objective optimization based multi-terminal transfer port berth resource allocation scheme was proposed. Considering the constraints such as the safe berthing time and distance of vessels and the container-vessel matching relationship, a multi-objective mixed integer programming model was established to minimize the time cost of vessels in the port and the transportation cost of transshipment containers between terminals. The proposed model was solved by NSGA-Ⅱ algorithm to obtain multiple sets of ship berthing and transshipment containers transportation plans under different scales. It is shown that the proposed algorithm can obtain multiple sets of Pareto frontier solutions, providing multiple optimization scenarios for port operators and shipping lines. And the results show a trend of a corresponding reduction in the cost of transshipment transport between transshipment container terminals at the expense of an increase of the time cost of vessel in port. Compared to traditional scheduling schemes based on minimum time cost, the proposed scheduling scheme effectively reduces the operating costs of vessels berthing in multiple terminals, and it has good robustness under uncertain scenarios. Specifically, it can reduce the total operating cost by 38.25% to 69.48% under different vessel scales. Through the time cost loss of ships in port to a lesser extent, the inter-terminal transshipment costs of transshipment containers can be significantly reduced, providing reference for berth allocation and inter-terminal transportation integration optimization for water-water transshipment. References | Related Articles | Metrics

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Trajectory Tracking and Vehicle Body Attitude Control of Differential Steering Unmanned Vehicles TIAN Jie, PAN Xin 2024, 43(7): 112-120.  DOI: 10.3969/j.issn.1674-0696.2024.07.14 Abstract ( )   PDF (2423KB) ( )   Aiming at the problem that the body of the distributed drive unmanned vehicle inclines outward under the centrifugal force when steering, which causes the loads of the inner wheels to decrease, the failure of the differential steering, and even the rollover of the vehicle in serious cases, a trajectory tracking and vehicle body attitude control method for the differential steering unmanned vehicle was proposed. The proposed method could achieve the trajectory tracking of the unmanned vehicle through the differential steering and meanwhile achieve actively inward tilting the vehicle body during the steering through the active suspension to ensure the effectiveness of differential steering, which improved the handling stability of the unmanned vehicles. Firstly, a vehicle model and reference model considering roll factors were established, and the reference front wheel steering angle required for the reference model to track the desired path was obtained through a fractional order single point preview driver model. Then, on this basis, an H∞ robust controller was designed, the reference values provided by the reference model were tracked respectively through the control of the yaw rate and body inclination angle of the differential steering unmanned vehicle. Finally, the required differential driving torque and the left and right active suspension control forces were obtained. The research results show that the designed fractional order single point preview driver model and H∞ robust controller can effectively ensure that the differential steering unmanned vehicle can achieve trajectory tracking and vehicle body attitude control at the same time. References | Related Articles | Metrics

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Design of HEV Engine Start-Stop Trigger System Combined with Road Information GAO Aiyun1, ZHANG Xingyuan1, FU Zhumu2 2024, 43(7): 121-128.  DOI: 10.3969/j.issn.1674-0696.2024.07.15 Abstract ( )   PDF (3808KB) ( )   For the existing engine start-stop system, the engine will stop as long as the engine meets the basic conditions of idle stop, resulting in frequent starting and stopping of the vehicle, which will not only aggravate the wear and tear of engine parts, but also increase the fuel consumption of the whole vehicle. To solve this problem, a hybrid electric vehicle engine start-stop trigger system (HEV-EST) combined with road information was designed. HEV-EST start-stop conditions were determined according to HEV engine idle and reboot fuel consumption chart. BP neural network number recognition algorithm and color recognition algorithm were used to construct the traffic signal recognition model. The queuing theory of overall planning was used to analyze and calculate traffic flow, constructing a traffic flow analysis model. Finally, HEV-EST was designed by combining the traffic signal recognition model and the traffic flow analysis model. Based on MATLAB simulation verification, the results demonstrate that the proposed system significantly reduces the number of invalid vehicle starts and stops and improves the overall vehicle fuel economy. References | Related Articles | Metrics

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Effect of Shot Peening Residual Stress on Stress Intensity Factor of Tooth Root Crack of Rail Vehicle Gear XU Xiangyang1, 2, SHI Huiyi1 2024, 43(7): 129-136.  DOI: 10.3969/j.issn.1674-0696.2024.07.16 Abstract ( )   PDF (7130KB) ( )   Fatigue fracture caused by tooth root cracks under high-cycle stress conditions is one of the main reasons for the strength failure of transmission gears in rail vehicles. In order to analyze the influence patterns and action mechanism of shot peening residual stress and tooth root bending stress coupling on the stress intensity factor of tooth root cracks of transmission gears of rail vehicles, a 20-node singular element 1/4-node displacement method was secondly developed based on the finite element method, aiming at the random characteristics of projectile positions during actual shot peening. A finite element method-discrete element method (FEM-DEM) coupled shot peening model and a three-dimensional single-tooth tooth root crack model were jointly established, and a set of multi-step joint numerical simulation method was formulated. The variation of stress intensity factor of tooth root cracks under the combined action of internal residual stress field and external loads was analyzed. The research results show that the residual compressive stress field introduced by shot peening reduces the stress intensity factor at the crack tip by approximately 12%, effectively suppressing fatigue crack propagation. The inhibitory effect of shot peening on crack propagation is most obvious on the surface and near surface areas and weakens as crack depth and external load increase. The stress intensity factor corresponding to residual stress is independent of external loads and only related to the initial stress state. References | Related Articles | Metrics