Abstract:The shield tail synchronous grouting area is located behind the shield tunnel segment wall. Due to its closed space, it is difficult to directly observe the slurry diffusion, which leads to the unclear distribution characteristics of synchronous grouting materials. Therefore, a shield tail synchronous grouting simulation device was developed, and the shield tail synchronous grouting simulation test was carried out. The pressure change in the soil mass and the settlement of the upper soil mass during the synchronous grouting process were studied. The results show that the pressure in the soil above the moving axis of the grout outlet gradually increases under the influence of the grouting pressure after the grouting starts, and gradually decreases after the grout outlet is far away. At the same time, the soil pressure on both sides of the axis gradually increases, resulting in an obvious soil arching effect; The internal pressure of grout after grouting stability is mainly determined by the upper load,which has no direct relationship with the grouting pressure in the grouting stage; The surface settlement caused by grouting is mainly determined by the grouting pressure, and secondly affected by the slurry property; The thickness of solidified grouting body is smaller in the transverse direction near the grout outlet, larger on both sides, and the thickness distribution is more uniform in the longitudinal direction.

Abstract:Based on the problem of adjacent construction of overpass bridge foundation and deep foundation pit of the underground station, this paper carried out a finite element numerical simulation of the whole construction process with Midas GTS NX where modified Mohr-Coulomb constitutive model was adapted on the soil, including foundation pit excavation, bridge foundation construction and braces demolition, to study the pattern of interaction between the bridge foundation and the underground station foundation pit. Having compared the numerical simulation results with on-site measured data, the results showed that, during the excavation stage of the foundation pit, the deformation of the foundation pit continued to increase due to the horizontal unloading of the soil. The maximum settlement occurred at about 0.4 times the width of the foundation pit from the edge of it, and the maximum displacement of diaphragm wall occurred near the bottom of foundation pit. After the construction of the overpass bridge foundation, the surface settlement of the foundation pit and the lateral displacement of the diaphragm wall further increased, and the overpass bridge itself also had a modicum settlement. Thanks to the protection of the enclosure structure, the impact of the braces demolition was neither obvious on the pit nor the overpass bridge foundation.

Abstract:In order to explore the horizontal deformation law of adjacent pile foundation under tunnel excavation, an analytical method of horizontal deformation response of adjacent pile foundation is proposed. Firstly, the freesoil displacements induced by tunneling can be calculated by Loganathan formula. The Euler -Bernoulli beam was applied to simulate pile and the Kerr foundation model was used to simulate soil-pile interaction, Then, the horizontal force equilibrium of the existing pile can be established, and the analytical solution of horizontal deformation of pile can be obtained. Compared with existing finite element GEPAN data, the calculating result of the proposed method can be verified. Compared with existing theory solution, this method is closer to finite element GEPAN data. The parameters results show that the depth of horizontal maximum deformation position of pile increases with increment with buried depth of tunnel and the maximum displacement of pile is increasing. The horizontal deformation of adjacent pile increases with the increment of ground lose rate. Horizontal displacement of pile foundation decreases with the increase of horizontal distance between pile foundation and tunnel, but the depth of horizontal maximum deformation position of pile decreases with the increment of tunnel -pile horizontal distance.

Abstract:In order to study how to accurately predict the development trend of track irregularity in the absence of historical data， a track irregularity prediction method that can consider the prior information of experts is proposed. The questionnaire survey method was used to obtain expert experience information and a Bayesian linear regression model with prior information was built up. Then the Markov chain Monte Carlo method was used to solve the model parameters. Finally, the amplitude of track irregularity was predicted and error analysis was conducted, and the prediction effects of different models in the absence of historical data were compared. The results show that the method can accurately predict the development trend of the track irregularity in the short term, and the correlation coefficients are all above 0.9. In the absence of historical data, the Bayesian linear regression model can also maintain a high prediction accuracy and the R2 is 0.88, which is 17% higher than the traditional linear regression model.

Abstract:In this paper, the vibration acceleration of the ballast bed, pillar and cover plate of a typical doubledeck metro depot was measured on site, and the characteristics of the vibration source and its transmission attenuation law were analyzed. The results show that the vibration of each ballast bed and pillar is not much different when the train passes through the first and second layers respectively, but the vibration attenuation of the first track bed-column is relatively large. The predominant frequency of the vibration of the cover plate is mainly concentrated in 30~80 Hz，and the vibration response of the measuring point near the center of the cover plate is greater than that at the end of the cover plate. The vibration response of the upper cover plate caused by the train running on the second floor of the operation zone is larger than that caused by the train running on the first floor. If the upper cover is developed, the vibration reduction design of the second floor should be considered. Whether it is a first-floor or a second -floor driving, the vibration is attenuated in the whole frequency range from the track bed to the column, and the low-frequency part of the vibration energy is easy to cause the resonance of the cover plate.

Abstract:In order to speed up the construction progress of the whole line, it is proposed to install additional track wells at a soon-to-be-completed grown-up station. To ensure the track-laying construction, some of the precipitation wells are temporarily closed, thus the groundwater level changes, thus causing a change in the calculation conditions of the floatation resistance of the existing station, which may have a negative impact on the station. The results show that, without considering the friction resistance between the main structure of the station and the enclosure structure, theamount of buoyancy near the railway track Wells is largeafter the closure of part of the precipitation Wells, and the influence degree of buoyancy is different in different parts of the station, so the anti-buoyancy measures should be considered separately. Under the condition of the same water level rise, the roof opening range and the maximum buoyancy of the main structure of the station show a nonlinear growth relationship. Therefore, different measures should be taken to suppress the buoyancy of the main structure of the station for the track wells, shield Wells and other special equipment wells with different opening ranges.

Abstract:In the critical period of epidemic prevention when a few infection cases occurred or the epidemics spread slightly in the city, public transit system offers the basic guarantee for urban trips. To ensure public transit operation performance and service quality during the critical period of epidemic prevention, the paper studies the dynamic game relationship between public transport supply and passenger demand from the perspective of service supply and demand matching. Aiming at the conflict states composed by the six strategies of the public transit provider and user in the critical period of epidemic prevention, a conflict graph model was constructed with the consideration of the balance and dynamic game between public transit providers and users. With sequence diagram, the relative preference of the decision-makers was ranked to the feasible states. For different types of conflict stabilities, the steady states were analyzed of the public transit provider and user. Case analysis was conducted on public transit of Suzhou to collect the preference of transit provider and user to different strategies via questionnaire. It is found that Nash steady state of public transit supply and demand is identified when the provider cuts transit shifts by 50% and stops transit service in isolation area, while the user stops unnecessary transit trips. The research provides scientific insights on public transit strategy in the critical period of epidemic prevention, conciliating the conflicts between transit supply and demand under special events for new balance.

Abstract:The research objective is to analyze the seismic resilience change characteristic of urban road network. Firstly, considering the spatial characteristic of earthquake and the comprehensive earthquake damage of road infrastructures, a link connectivity probability model based on intensity attenuation distribution was constructed, thus vulnerable sections were identified. Then, the seismic resilience of specific network under different scenarios was analyzed using a network structural resilience assessment model which considered 3 dimensions. Evaluation results of the effects of these vulnerable links elimination in the network show that network resilience was still strong when a few roads cancelled, while this ability was significantly getting poor after the cumulative attack on the other vulnerable sections. Therefore, network transportation efficiency was reduced, and the connection between nodes were weakened.

Abstract:For the traffic oversaturation situation, it proposed a method to estimate the cycle initial queue length and maximum queue length based on the traffic shock wave by using the information of vehicle trajectory data such as vehicle arrival and parking location. Based on the trajectory of connected vehicles, the four critical points of vehicle arrival time, queuing time, start time and departure time were determined according to the arrival rate of each cycle according to the information provided by the critical point, and the initial queue length and maximum queuing length of each cycle were estimated by using shock wave theory, and the model was simulated and verified by the micro traffic simulation software SUMO. The experimental results show that the penetration rate of connected vehicles is not less than 20%, when v/c=1.0, the initial queue length MAE value is less than 6.5 meters, the MAE value is less than 10%, the MAE value of the maximum queue length less than 16.0 meters, and the MAPE value is less than 11%, indicating the intersection queuing length estimation model based on vehicle trajectory can still estimate the maximum queuing length and initial queue length of supersaturated intersections more effectively.

Abstract:Aiming at the system errors caused by uncertain running resistances, model errors and other factors during the high-speed train operation, a new adaptive error compensation control scheme based on characteristic model was proposed to realize the asymptotic tracking of a given target speed curve. Firstly, the characteristic model of high-speed train with system errors was derived based on the characteristic modeling method and the parameter identification by the dynamic analysis of high-speed train. Secondly, an adaptive error compensation controller for high-speed train based on the characteristic model was designed by employing the ability of the extended state observer for the system error estimations, and the controller parameters were optimized based on the generalized minimum variance method, to achieve asymptotic tracking of a given speed profile even in the presence of the system errors. Such a control strategy can effectively deal with the uncertainties caused by system errors, improve the control accuracy, and guarantee the safe and reliable operation of high-speed train. To verify the effectiveness of the method proposed in this paper, simulation experiments were conducted by using the CRH380A type high-speed train as the controlled object. Simulation results show that the compensation control method designed in this paper has desired control performance despite the existence of unknown system errors.

Abstract:As a typical unsupervised learning model in neural networks, the self-encoder has attracted widespread attention in various areas, and its application in rolling bearing fault diagnosis is increasing with obvious advantages in data noise reduction and data visualization dimension reduction. In order to timely understand and master the application of auto-encoder and its improved algorithm in rolling bearing, this paper classifies and summarizes the representative auto-encoder related algorithms in recent years. Firstly, the principle of self-encoder and the theoretical sketch of several self-encoder methods based on its improvement are described, and the improvement purpose and improvement of these algorithms are analyzed. Then, the applications of these algorithms in the field of rolling bearing fault diagnosis are listed. Finally, the problems of present-day self-encoders and their improved algorithms are summarized, and the ideas for solving them are analyzed.

Abstract:Self-healing material is usually used as a mechanical component, which not only needs to consider the topological optimization of the macro-configuration of the structure, but also the influence of the size and distribution of self-healing agent carrier microcapsules on the mechanical properties and healing effect of self-healing material. Therefore, the collaborative optimization of structural macroscopic configuration and internal microcapsules is of great significance. Based on movable morphable component, using structural compliance as the objective function, the material area as constraint condition, a two-dimensional mathematical model with built-in microcapsules component was established. Based on the method of moving asymptote (MMA), collaborative optimization design method of self-healing materials was given, and compared with the classic self-healing materials, the superiority of collaborative optimization was verified. The results show that: The configuration of two self-healing materials is similar; The structural compliance of the two kinds of self-healing materials increases with the increase of microcapsule volume fraction, and the mechanical properties deteriorated to different degrees; Compared with the classical self -healing materials, the collaborative optimized self -healing materials showed more excellent mechanical properties with the increase of volume fraction. When the volume fraction is close to 14%, the compliance of the collaborative optimized self-healing materials is only 66.1% of that of the classical self-healing materials.

Abstract:Aiming at the safety problem of rash entry in the process of high frequency and long time dynamic test in rail vehicle production base, a new infrared anti-rash entry system is developed. According to the principle of infrared alarm, infrared transmitting and receiving devices are symmetrically installed on both sides of the vehicle dynamic test line. The infrared signal reception will be interrupted when the vehicle intrudes unlawfully, thus triggering the alarm device installed in the vehicle cab, triggering the electrical signal and transmitting it to the vehicle undergoing dynamic test, and issuing the command to start the vehicle emergency braking system, so as to ensure the safety of operation. The system solves the safety problems caused by human uncontrollable, equipment signal error, external interference and other factors. Meanwhile, the system is simple and reliable with low cost and convenient for long-term maintenance in the later period.

Abstract:Aiming at the problems of complex faults, outdated maintenance methods and lagging maintenance manual in the maintenance work of EMU coupler, an auxiliary maintenance method of EMU coupler based on mixed reality technology was proposed. With the help of mixed reality and data interaction technology, the overall model and technical framework of MR auxiliary maintenance for the fault of EMU coupler were constructed. The key technologies such as virtual-real registration fusion, intelligent fault diagnosis, data information interaction and maintenance assistance guidance were studied, and various human -computer interaction assistance maintenance methods such as gesture recognition and eye tracking based on Unity3D-HoloLens were realized.

Abstract:This paper adopts a multi-period double difference method to match city data and railway data of 10 prefecture-level cities in Zhejiang Province, except Zhoushan City, from 2006 to 2019 to explore the impact of the opening of high-speed railway (HSR) on the income gap between urban and rural residents. The study finds that the opening of HSR and the increase in the frequency of railway trains have substantially increased the real accessibility of cities in Zhejiang Province； The opening of HSR as a whole widens the income gap between urban and rural residents in prefecture -level cities in Zhejiang Province, with changes in urban accessibility caused by changes in the frequency of railway trains playing a mediating role, and there is heterogeneity in the number of districts and counties served by HSR in this effect； There is an early effect of the impact of HSR, which narrows the income gap between urban and rural residents in the region from the time when HSR construction begins.