In recent years, spatial-temporal graph convolutional network (STGCN) has been introduced into traffic flow prediction, which has good spatial-temporal traffic data modeling ability and has achieved advanced performance, but there are still two problems: ①Traffic flow data have strong temporal and spatial correlation; ②Static pre-defined graphs are difficult to capture the spatio-temporal dependence of dynamic changes in traffic flow over time. To solve the above problems, a new spatial-temporal decomposed framework (STDF) was proposed, which used residual connection, forgetting gate and update gate to organically connect time module and space module to decompose and predict input information in multiple dimensions. In addition, by instantiating STDF, a new traffic prediction model based on input traffic signal decomposition decomposed dynamic spatial-temporal graph convolutional network (DDSTGCN) was proposed. It captured the spatiotemporal dependencies of traffic and designed a dynamic graph learning module that takes into account the dynamic nature of spatial dependencies. Finally, two real traffic flow data were used to compare with the existing traffic flow prediction algorithms. The experimental results show that the proposed method has good performance in the accuracy of traffic flow prediction and can effectively complete the traffic flow prediction in the real scenario.

The evaluation of on-street parking efficiency is considered a necessary basis for the optimization and management of on-street parking as well as the development of urban intelligent parking systems. Therefore, an evaluation method of on-street parking efficiency based on the entropy weight Critic-Topsis model was proposed. Firstly, nine indexes, such as the number of parking spaces, the remaining width of the road, and the cumulative number of parking, were selected from three aspects: parking space attributes, operating characteristics, and traffic impact, to construct the evaluation index system of on-street parking efficiency. Secondly, an evaluation method of the entropy weight Critic-Topsis model was proposed based on the data characteristics of the evaluation index of on-street parking efficiency. The entropy weight method and Critic method were employed to calculate the weight of each index, and then the improved topsis model was utilized to quantitatively evaluate the parking lots. Finally, this model was utilized to analyze the data of 10 on-street parking lots in Beijing, resulting in the evaluation results and rankings for each parking lot. It is found that in the evaluation index system of on-street parking efficiency, the number of parking spaces, the utilization rate of parking spaces, and the remaining width of the road have significant influences on the evaluation results, with weights of 22.99%, 13.72%, and 13.71% respectively. In the case analysis of 10 on-street parking lots in Beijing, higher scores are observed for on-street parking lots such as Gongti East Road, Keyuan Road, and Huayuan North Road, which are 0.659 4, 0.611 3, and 0.608 1, respectively. Moreover, relevant suggestions and optimization measures are provided for the on-street parking lots of Chunhe Road and Lingnan Road, which have lower scores, aiming to enhance the long-term management system of urban on-street parking and improve the level of urban traffic management.

To achieve safe and efficient replacement of stay cables that exceeded their designed service life or suffer serious damage, a stay-cable replacement system (SRS) was proposed which used the existing cable-stayed anchor plate (ECAP) as a reaction force system. The scaled model of the typical main girder segment and the full-scale model of the SRS were designed and produced. The axial compression and eccentric compression static tests were carried out under the conditions of dry contact and adhesive contact between the steel anchor barrel (SAB) of SRS and the ECAP. The results show that, under dry contact conditions, the failure mode of the SAB is the buckling of the contact point between the eccentric compression side of the SAB end and the ECAP. Under adhesive contact conditions, the failure mode of the SAB is the buckling at the interface between the eccentric compression side of the SAB and the epoxy resin glue. After pouring of the epoxy resin glue, the displacement and maximum compressive stress of the SAB are smaller, and the compressive safety and stability of the SAB are better. The proposed SRS can be applied in stay-cable replacement.

Variations in freezing and thawing of the roadbed are known to significantly influence the dynamic behavior of high-speed railway ballast tracks. This phenomenon potentially compromises the safety and efficiency of train operations. A comprehensive vehicle-ballastless track-roadbed spatial dynamic model was employed to examine the effects of different wavelengths, amplitudes, and velocities on track dynamics due to roadbed frost heave. It was found that, with a constant heave amplitude, an increase in wavelength initially boosted and then reduced the car’s vibration acceleration. Concurrently, the vertical wheel-rail force diminished as the wavelength extended, leading to a decrease in both the wheel load reduction rate and the risk of derailment. Conversely, when the wavelength was kept steady and the heave amplitude was increased, the car’s peak vibration acceleration escalated. At a 40 mm amplitude, the vertical wheel-rail force peaked at 198.642 kN before dropping to zero within 1.384 seconds, resulting in a brief airborne phase for the car. An increase in heave amplitude heightened both the wheel load reduction rate and the derailment coefficient, reaching critical safety thresholds at a 35 mm amplitude. Higher driving speeds intensified the dynamic indicators of the rail system.These insights provide crucial guidance for analyzing dynamic challenges in high-speed railway tracks and addressing structural issues effectively.

During the parallel operation of excavation and concrete lining construction in the diversion tunnel, the quality of construction was significantly affected due to the severe damage to the floor concrete caused by heavy truck crush. In response to the challenging problem of floor concrete protection caused by heavy truck crush during the “excavation-lining” parallel operation in the diversion tunnel, a numerical calculation model for floor protection was established using ABAQUS. Adopting the floor protection measure of overlaying “tunnel excavation debris-concrete” composite protection layer, a numerical simulation study on the protection of tunnel floor concrete was conducted. The influence patterns of the material characteristics of the protection layer and the bias distance of the heavy truck on the stress and deformation of the floor concrete were analyzed, and the effectiveness of protection under different working conditions was evaluated. The study results indicated that the floor protection measures could effectively improve the protection of the floor concrete. As the concrete grade of the protection layer increased, the stress and deformation of the floor concrete decreased, with the reduction rate reaching up to 17.5% and 12.4% respectively. Furthermore, as the bias distance of the heavy truck increased, the maximum deformation of the floor concrete increased, and the range of deformation expanded significantly. Moreover, stress growth was extremely pronounced at the edges, with a maximum growth rate of up to 222.6%. The research results can provide theoretical and technical guidance for the protection of the floor concrete against crush damage in the diversion tunnel.

Efficient and accurate crack detection can provide a basis for assessing the structural safety of tunnels. Aiming at the shortcomings of traditional crack detection methods, which are complex and weak in generalization ability, an improved algorithm YOLOv5-CT(YOLOv5 CBAM Transformer) for tunnel lining crack detection was proposed.Considering the slender morphology of the cracks, the network introduced the Transformer module to improve the crack detection effect.The strong long-range dependency capture ability of the Transformer module enabled the proposed detection model to fully learn the contextual information of the crack region. In addition, the network integrated the convolutional attention mechanism CBAM(convolutional block attention module) in neck.The experiment shows that the YOLOv5-CT can achieve AP50 and AP of 85.2% and 51.3%, respectively, which is an improvement of 8.9% and 12.1% compared to the baseline model YOLOv5. It is better than other one-stage object detection networks in terms of accuracy, and the inference speed reaches 161.3 fps under 640×640 pixel conditions, which meets real-time detection of tunnel lining cracks.

The current safety evaluation standards lack guidance on the alignment design specific to lower-grade highways, such as four-lane and non-standard highways. To address this issue, a method for assessing the driving safety of mountainous highways with low index and complex alignment was proposed. The method involved building a human-vehicle-road system simulation using the CarSIM/TruckSIM simulation software platform, selecting representative car models, and using realing vehicle driving data as simulation parameters to carry out virtual vehicle driving tests. Four categories of indicators, including speed, lateral stability, driver handling, and speed regulation, were used to examine and analyze the compliance of the tested highway’s geometric design, speed coordination, driving operation load, identification of accident-prone sections, and safety of continuous uphill sections. The feasibility of the “human-vehicle-road” simulation method was verified by running virtual simulation driving tests similar to the real-vehicle test, and one four-lane highway and one non-standard highway were selected as examples. The results demonstrate that this method can effectively identify alignment design combinations that are below the limit and inconsistent, as well as road sections with high driver handling loads and poor balance. It can also identify dangerous road sections, corresponding vehicle accident patterns, critical safety speeds, and positions and widths where heavy-duty trucks deviate from the travel lane when passing through hairpin curves. Based on the driving/accident conditions of dangerous road sections, targeted geometric parameter improvement measures can be proposed to enhance the trafficability and stability of vehicles on ordinary mountainous highways with low index and complex alignment, ultimately improving the quality of alignment design and driving safety for low-index highways in mountainous areas.

A large number of loess landfills have been generated by the Pingshan land formation project carried out in Lanzhou area, which has a large safety hazard due to its low compaction and lack of necessary protection, resulting in the extensive development of geologic hazards such as loess caves, landslides, and so on. The pore microstructure of in-situ loess landfill with different water content was quantitatively studied through scanning electron microscope and Image J software, combined with fractal theory, the pore type, number, area, and change rule of the number of dimensions of the pore of the landfill loess with different water content was obtained, and the dynamic relationship between the pore structure and the wetting of loess and development of the caves were preliminarily analyzed. The results show that: with the increase of water content, the number and area of large and medium-sized hollow pores gradually decrease, while the number and area of small hollow pores decrease, but the area of small hollow pores increase, and the collapse of large and medium-sized hollow pores is the main reason for wet subsidence and deformation of loess; the pore dimension number of landfill topsoil has a linear negative correlation with water content, and a positive correlation with wet subsidence; the average pore dimension number of in-situ topsoil is 1.251, and the average pore structure is 1.251. The average pore dimension is 1.251; based on the characteristics of cave development in loess landfill, it is proposed that the protection treatment should be carried out in three aspects, such as the construction of drainage ditches, the reinforcement of caves, and the protection of slopes. The research results can provide theoretical support for the engineering construction and geologic disaster prevention and control research in Lanzhou landfill loess area.

In order to further study the connectivity and hydraulic connection between the injection and production wells in geothermal reservoir, a dual media model of fracture-porosity was constructed by using COMSOL Multiphysic.The effects of the aperture of the fissure group in fractured rock mass, the diffusion coefficient of the rock matrix, and the permeability on the tracer breakthrough curve (BTC) at different dip angles with the mainstream direction were analyzed.The results indicate that the convection of water in the fissure is the main factor influencing the concentration migration. With the increase of the fissure aperture, the migration rate and peak concentration of the tracer are enhanced, and the degree of the influence on the tracer migration by the fissure aperture decreases with the increase of the dip angle of the fissure group. The diffusion coefficient and permeability of the rock matrix have a significant impact on the temporal and spatial distribution of the tracer concentration. With the increase of the matrix diffusion coefficient, the delay effect of the tracer migration is elevated. With the increase of the matrix permeability, the anisotropy of the reservoir pressure and concentration distribution is reduced, and the concentration distribution at the outlet boundary becomes more uniform.

With the development of the energy industry and the continuous growth of global energy demand, the exploration and development of geothermal resources have become increasingly difficult. Deep and ultra-deep geothermal resources have been identified as a key direction for the development of the new energy industry. As the drilling depth for geothermal wells continues to increase, the thermal and physical properties of the drilling fluid are found to have a more significant impact on the calculation of wellbore temperature and pressure amid changes in temperature and pressure. In A coupled numerical model of transient temperature and pressure in the wellbore during the drilling of geothermal wells was established, and the influence of the density and viscosity of drilling fluid on the calculation of wellbore temperature and pressure with changes in temperature and pressure during the drilling of geothermal wells was studied. It was shown by the calculation results that the viscosity and density of the drilling fluid significantly affected the calculation of wellbore temperature. When the changes in viscosity with temperature are considered, the calculation results of wellbore temperature are found to be 3.1% higher, and when changes in viscosity and density with both temperature and pressure are considered simultaneously, the results are 4.99% higher, compared with the case where changes in viscosity with temperature are not taken into account; To improve the accuracy of calculations, the thermal and physical properties of drilling fluid should be fully considered in calculating the temperature and pressure of geothermal wells.