Abstract:【Objective】To study the vibration characteristics of subway stations caused by the entry and exit of three-line parallel subway stations.【Method】Taking a third-line parallel transfer subway station in a domestic city as the research object,the vibration characteristics and propagation rules of the station were analyzed based on the field measured data.【Results】Affected by the completion and operation of the line,the vibration response of each platform in the station varied greatly. Under the inbound condition,the average Z vibration levels of platforms 1,2 and C were 81.9,91.4, 61.7 dB,and the main frequency bands of platform 1 and 2 were 75~125 Hz. Under outbound conditions,the average Z vibration levels of the three platforms were 82.7,93.8, 63.7 dB,the main frequency band of vibration of platforms 1 and 2 is 50~100 Hz, while the vibration response of platform C is concentrated within 50~60 Hz under both conditions.【Conclusion】In most measuring points in the station, it can be found that the vibration under outbound conditions is greater than that under inbound conditions, and the maximum difference is about 2.5 dB. After the vehicle-induced vibration is transmitted to the ground floor, it will first produce a certain attenuation, and when it is transmitted to the ground floor, it will produce amplification, and the vibration is about 3.6~5 dB. The attenuation of vehicle-induced vibration transmitted in the station building is small, and the vibration attenuation mainly depends on the soil layer, and the vibration attenuation is about 0.53 dB/m. The research results can provide a reference for vibration prediction, vibration comfort evaluation and vibration reduction design of similar structures, subway stations and buildings with parallel access to multiple lines.

Abstract:【Objective】In order to study the displacement variation law of adjacent underground pipelines during the excavation of deep foundation pits.【Method】Based on a deep foundation pit project of Nanchang No.4 line, FLAC 3D software is used to simulate the whole process of dynamic construction of foundation pit, and the influence of different pipe materials, pipe diameter, buried depth and buried distance of internal support on pipeline displacement is analyzed. And the field deformation monitoring data are used for comparison and verification.【Result】The results show that the internal support plays a good role in limiting the displacement of the adjacent pipeline during the construction of the foundation pit. In the process of foundation pit excavation, the change of pipe material and pipe diameter mainly affects the settlement of pipeline.【Conclusion】The stiffness of different types of pipes is different. The greater the stiffness, the stronger the pipeline's ability to resist soil deformation. The settlement variation of the pipeline is negatively correlated with the variation of the pipe diameter. The buried depth of the pipeline has a significant effect on the horizontal displacement of the pipeline. The horizontal displacement of the pipeline increases first and then decreases with the increase of the buried depth, and reaches the maximum when the buried depth of the pipeline is close to 1/2 of the design depth of the foundation pit. Under the principle of following a single variable, there are differences in the influence range of displacement of pipelines with different buried distances. Compared with pipeline settlement, foundation pit excavation has a greater influence range on the horizontal displacement of adjacent pipelines.

Abstract:【Objective】To master the deformation characteristics and the law of energy dissipation of Jiangxi red clay under the condition of shear loading-unloading.【Methods】The direct shear loading-unloading tests are finished, and the strength and deformation properties and the law of energy dissipation are studied.【Results】The mechanical behavior of red clay under various normal stresses, including shear stress, shear displacement, normal displacement and energy dissipation, are obtained.【Conclusion】The dissipation energy increase rate under shear loading and unloading is comparatively lower for low normal stress as compared to high normal stress. On the whole, the dissipation of energy has positive correlation with the normal stress, and the greater the normal stress, the greater the energy consumed by the plastic deformation. The dissipated energy under the same unloading conditions increases with the increasing of numbers of unloading the red clay exhibits shear shrinkage during unloading and loading in a direct shear test. Normal displacement increases during the unloading stage, followed by an increase and then decrease during reloading, resulting in shear expansion deformation. Shear expansion ends when the shear displacement reaches its value before unloading. Shear unloading will increase the normal displacement and the shear shrinkage of red clay, and this effect of unloading on the normal displacement becomes weaker with the increase of normal stress.

Abstract:【Objective】Based on the data of similar material proportions in large-scale model tests of highway tunnels, research on the preparation method of similar materials for large tunnel surrounding rock. Develop a liquid-solid coupling similar material composed of barite powder, quartz sand, white cement, iron powder, silicone oil, and water.【Method】Exploring the influence of different ratios on various physical properties and water rationality of materials through indoor experiments, and the specific ratio results of liquid-solid coupling similar materials were determined.【Result】The experimental results indicate that an increase in the content of white cement will significantly reduce the permeability coefficient of the material, while the binder will significantly affect the elastic modulus and compressive strength of the material, while the content of white cement remains un-changed. In addition, as the proportion of barite powder to white cement in the material gradually increases, the compressive strength of the test material will gradually increase. However, when the content of barite powder and white cement in the material reaches a certain level, the compressive strength of the material may slightly decrease. Increasing the ratio of barite powder to white cement within a certain range can improve the elastic modulus of the material. The shear strength is significantly affected by silicone oil.【Conclusion】Liquid solid coupling similar materials can simulate rock mass materials with different strengths and permeability, making them an ideal similar simulation material.

Abstract:【Objective】In order to study the local load transfer mechanism and mechanical properties of tunnel lining reinforced with corrugated steel plate lining.【Method】The tunnel lining unit was regarded as a beam unit, and a bending performance test of concrete beam reinforced with corrugated steel plate was carried out. Establish a corresponding three-dimensional refined finite element model, verify the model through test results, and analyze the load transfer mechanism.【Result】Research results show that compared with unreinforced beams, the ultimate load of beams reinforced with corrugated steel plates is increased by 30% to 41%, and the ultimate load increases with the increase in the number of anchor bolts. The relative slip between the corrugated steel plate and the concrete structure decreases as the number of anchor bolts increases. At the initial stage of loading, the corrugated steel plate is in the neutral layer position, and the strain is basically zero; after reaching the cracking load, the entire corrugated steel plate peak is in a compressive state, while the corrugated steel plate trough is always in a tensile state.【Conclusion】Finally, through the finite element software analysis, the failure mode of the specimen and the load-strain of the corrugated steel plate are verified. The simulation results are in good agreement with the experimental results.

Abstract:【Objective】 To study the load-bearing capacity of variable span and amplitude steel trestle bridges under multiple loading conditions.【Method】 A steel trestle bridge in the construction of the Xiangtang-Putian left line special bridge on the Xiangtang-Putian connection railway line is taken as the research object. A numerical model was established by using the bridge limited element software Midas civil to carefully study the stress state of each component under five different conditions.【Result】 The results show that the bailey beam has a large safety margin under different conditions; the safety margin factor of the pile top distribution beam is small under condition 1 and 2, reaching only 1.23 and 1.20, and the safety margin factor of its stiffness is 1.20 under condition 5. It is necessary to avoid excessive temporary loads during construction; the positive stress safety margin factor of the steel tube column under condition 5 is only 1.50, and measures should be taken to ensure safety during construction; the design of the triangular area at the corner meets the structural performance requirements. 【Conclusion】 The results may provide some reference for the design of similar trestle bridges.

Abstract:【Objective】The influence of blasting excavation of underground cavern group on the safety and stability of adjacent cavern was researched.【Method】Based on an underground reserve project, this study carried out an analysis of the influence of blasting excavation of underground cavern group dome on adjacent cavern, and the influence of different burial depths on the dynamic response of adjacent cavern was studied.【Result】 The result shows that the blasting excavation conditions of branch tunnel are in the relationship of up or down tunneling, and the displacement response and vibration velocity response are mainly in the vertical direction. The shear stress of the main tunnel mainly extends to the hance, and the maximum shear stress appears near the middle of the straight wall, but it is still within the tensile strength range of the surrounding rock of the main tunnel.During blasting excavation of the outer ring of the dome, the vibration velocity and displacement response of the corresponding inner circle structure are larger. The vault and hance are in the horizontal direction, and the skewback is in the vertical direction. The maximum tensile stress and shear stress appear in the surrounding rock near the arch foot.【Conclusion】Steel supports can be set at the junction of the dome inner circle and outer ring to strengthen the stability of the dome inner circle structure. When the cavity is in deep burial state, under the same blasting conditions, the burial depth has almost no influence on the vibration velocity response of the adjacent cavity.

Abstract:【Objective】Vehicle detection is critical for urban intelligent transportation. Focusing on small target problems, high-density problems, and motion attribute problems, this study takes traffic surveillance images as input and aims to detect moving vehicles.【Method】Based on the anchor-free CenteNet, a detection method of multi-scale features and dual-source motion perception was proposed. Firstly, coordinate attention was introduced to the multi-scale and global context features of the network's abstraction layer, so as to supplement information in multiple stages and at multiple levels and improve the model's understanding of vehicles and scenes. Secondly, through fuzzy textures representing actual motion features of vehicles and optical flow knowledge representing general motion features of vehicles, the model's perception ability of moving vehicles was constructed. 【Result】The experimental data came from the public dataset UA-DETRAC. The mean average precision (mAP) and frames per second (FPS) were used as the evaluation metrics of accuracy and speed. Experiment results show that the mAP and FPS of the proposed method are 70% and 30 frame/s respectively, which have the best balance between speed and accuracy among other compared methods.【Conclusion】It maintains that the proposed method is competent in the task of moving vehicle detection.

Abstract:【Objective】To meet the application requirements of miniaturized and multifunctional dielectric resonator antennas (DRA) in wireless communication systems, such as the Internet of Vehicles (IoV).【Method】A wideband filtering dielectric resonator antenna based on a microstrip-dual mode slotline resonator feeding structure is proposed. In the antenna design process, the traditional slotline of the microstrip-slotline coupled feeding structure was replaced by a dual mode slotline resonator, forming a novel microstrip-dual mode slotline resonator coupling feeding network. This dual mode slotline resonator served as an energy coupler in the feeding network, which effectively excited the TE₁₁₁ resonant mode of the DRA; At the same time, two slotline resonant modes could also be generated to participate in antenna resonance, broadening the antenna bandwidth. Additionally, by introducing a spur line on the microstrip feedline and combining the intrinsic resonance characteristics of the slotline resonator, a radiation null can be produced on both sides of the antenna passband, showing a quasi-elliptical filter response on the gain curve.【Result】To further verify the performance of the antenna design, a pro-totype FDRA was fabricated and measured, and the measurement and simulation results were generally consistent. The central frequency of the antenna is 4.12 GHz, the impedance bandwidth is 53.40 % (3.02~5.22 GHz), and the in-band flat gain is 5.7 dBi.【Conclusion】The antenna meets the application requirements of wireless communication systems, such as 5G and telematics.

Abstract:【Objective】There are many characteristics of the box culvert tunnel, such as large section, slow construction progress and instability excavation face.【Method】Based on the project of shallow buried tunnel section of Luzhou Avenue in Binhu Science City of Hefei City, this study used limit equilibrium theory, Mohr-Coulomb strength criterion and full overburden weight theory to carry out theoretical derivation, and combined with large-scale three-dimensional fine numerical model to study the limit support pressure of excavation face. 【Result】The results show that : it proposed a simple calculation method for the limit support pressure of the excavation face of large-section box culvert tunnel under the action of pipe curtain. Based on this, according to the calculated value of Bishop slice method, the error was very small. Compared with the calculated value of the limit support pressure proposed in this paper, which proves the accuracy of the method. Through the establishment of three-dimensional numerical model of pipe curtain box culvert construction, it is found that the surface settle-ment and the displacement of the longitudinal axis of the excavation face gradually decrease with the increase of the support pressure and tend to be stable. When the support pressure exceeds the static earth pressure, the upper soil is subjected to strong extrusion, and the excavation face state is easy to be inverted S shape.【Conclusion】The above results can be used as a reference for related projects.

Abstract:【Objective】Collaborative optimization of departure intervals and vehicle utilization plans for hybrid buses composed of fuel powered and electric buses, with the goal of minimizing the smoothness of departure intervals and overall operating costs.【Method】With multiple constraints being considered, including departure interval range, number of vehicles, vehicle connectivity, and electric bus range, an optimization model was established to improve these aspects. A genetic algorithm was designed to solve the two-stage model, enhancing efficiency and accuracy of the solution.【Results】The case study shows that compared with existing operational plans, the optimized model can save the total operating cost of vehicles by up to 13.04% under relatively uniform departure intervals.【Conclusion】This optimization model could allocate the number of buses used more reasonably with a relatively uniform departure interval, achieved off-peak charging for electric buses and enhanced vehicle utilization.

Abstract:【Purpose】To enable conflict avoidance operation planning for support vehicles in complex environments, a dynamic priority classification method is proposed.【Method】This method prioritizes conflict avoidance based on levels of operation efficiency and risk. Additionally, a conflict avoidance operation planning model were established, along with a two-stage algorithm for global path optimization. A low time complexity conflict detection method was also proposed to ensure accuracy in solving large-scale complex problems quickly. 【Result】Compared to the fixed-priority-based two-stage algorithm, the proposed approach improves conflict point reduction by 7.6% and reduces the vehicle-aircraft conflict ratio by 7.5% .【Conclusion】The proposed method meets the requirements of ensuring differentiated vehicle operation, and realizes the function of conflict avoidance path planning in a mixed operation environment of vehicles and aircraft.

Abstract:【Object】Explore the vibration characteristics of high-speed train gearbox housing under the coupling excitation of wheel polygon and rail corrugation.【Method】The rigid-flexible coupling dynamic model of wheelset, gearbox housing and track was established. Three vibration acceleration sensors were arranged in the gearbox housing, and dynamic simulation was carried out under different working conditions to analyze the vibration acceleration of each measuring point of gearbox housing.【Result】Under the wheel-rail coupling excitation, at the same speed and with the wheel polygon of 23rd order and the amplitude of 0.010 mm, the root mean square value of the vibration acceleration of each measuring point is the largest, and the wheel polygon has the greatest influence on the measuring point B in the three measuring points. Under the excitation of rail corrugation, the root mean square value of vibration acceleration of measuring point B is the largest among the three measuring points under the combined action of harmonic torque of traction motor and gear meshing. The root mean square value of vibration acceleration of measuring points A and C increases with the increase of amplitude. Compared with the wheel-rail coupling excitation with broad spectrum, the vibration frequency caused by wheel-rail excitation is close to the 5th order natural frequency of the gearbox housing, which induces resonance. 【Conclusion】The resonance can be avoided by changing the speed of the train or changing the structure of the gearbox.

Abstract:【Objective】Aiming at the characteristics of various target scales, complex background and dense small targets in aerial images of unmanned aerial vehicles (UAC), a small target detection algorithm LM-YOLO based on YOLOV5 is proposed.【Method】Firstly, the number of small target detection head was increased and K-DBSCAN clustering algorithm was used to optimize the anchor frame, so as to generate an anchor frame more suitable for small target detection and improve the detection accuracy of the algorithm. Then, a more efficient MobileNetV3-CBAM was designed as a feature extraction network to reduce the size of the network model. Finally, the large kernel selective attention mechanism LSK was introduced into the feature fusion network to increase the resolution of the model to similar targets.【Result】The experimental results on the public data set VisDrone2019 show that the average detection accuracy of LM-YOLO for all targets is improved by 7.6% and the model size is reduced by 45% compared with the benchmark model YOLOV5.【Conclusion】Experiments show that the proposed algorithm can reduce the model size while maintaining good detection accuracy.