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This paper first systematically reviews the research on shield and TBM construction ventilation technology in the tunnel (hole) and coal mine roadway engineering; then, it briefly introduces the general situation of the main and auxiliary inclined shaft project of Kekegai Coal Mine and makes a theoretical analysis on the ventilation design principle and ventilation mode selection of the project according to the general situation of the project. Based on the above analysis, a variety of designs and comparisons of construction ventilation schemes are carried out, and it is decided that the two-stage single head forced ventilation scheme with replacement fan is adopted for both inclined shafts; then the selected ventilation scheme is checked theoretically; finally, the ventilation effect is tested. The field practice shows that the ventilation effect is good.

For 70% low-floor trains on the light rail lines in Changchun, a multi-linkage forced steering device (FSD) is developed aiming at relieving the independently rotating wheelset (IRW) excessive flange wear and improving IRW bogie system running safety on curve line. This FSD employs guiding mode of steering four independently rotating wheels separately in a two-axle bogie, that is, four FSDs are employed to work together to realize the steering of a two-axle bogie. One side of an FSD is connected to the axle of an independently rotating wheel while the other side is attached to the front or rear vehicle body. When train passes through curve, the yaw angle between the IRW bogie and the front or rear carbody drives the linkage system to rotate to guide the independently rotating wheel towards its radial position. The coupled vehicle-track dynamics model for a 6-module single-type low-floor light rail train is developed and simulations of the train passing through tangent and curved tracks with and without FSD proposed are carried out. The results indicate that the FSD can improve the IRW restoring capability on tangent track and curve negotiation performance on whether sharp, medium, or large curved track. For example, passing through a curve with a radius of 200m, the IRW friction work has the biggest drop by 62.07% and the wheelset attack angle is second with a reduction rate of 55.02%. Adopting of larger steering stiffness, smaller steering clearance, and lever ratio greater than the ideal value can guarantee the higher steering ability of FSD. Besides, lower longitudinal stiffness of the trailer primary suspension is recommended because it can also enhance the steering ability of the FSD. [ABSTRACT FROM AUTHOR]

The vibration caused by urban rail transit has led to numerous severe environmental issues. The floating slab track (FST) plays an important role in vibration control and noise reduction for rail transit. In this study, a novel phononic crystal vibration isolator (NPCVI) is developed based on the principle of local resonance to address the deficiencies in the low frequency vibration reduction of existing FST with steel spring vibration isolators (SSVI). The vibration equation of the NPCVI is derived and an analytical method for the dynamic interaction between vehicle, track, and tunnel is proposed. The pseudo excitation method (PEM) is introduced to solve the random vibration response of the vehicle-track-tunnel coupled system under the excitation of full-band track random irregularity. The numerical simulation results are compared with the field measurement results to verify the correctness of the solution model. The vibration reduction analysis of FST using NPCVI is conducted within a system dynamics framework, and a comparison is made between the performance of the conventional SSVI and the proposed NPCVI while a train is passing. The vibration reduction optimization effect of the NPCVI is evaluated using the vibration level (VL) of the tunnel structure. The results demonstrate that the NPCVI exhibits a superior band gap width as compared to that of the SSVI. [ABSTRACT FROM AUTHOR]

The fracture phenomenon of fastener clips occurs frequently in the sections with serious rail corrugation of high-speed railway, which brings huge potential safety hazards to track service and driving safety. In order to prevent the vibration fatigue fracture of fastener clips in high-speed railway, a dynamic vibration absorber (DVA) for clips is proposed in this paper to suppress the primary sensitive frequency of the corresponding resonant of clips. Firstly, based on the optimal design theory of DVA, a parameters design method of ring-shaped DVA suitable for clips is proposed. Secondly, the vibration characteristics of the high-speed railway fastener system are investigated, and the main reason for the fastener clips fracture is analyzed by simulation analysis combined with filed test. Then, focusing on the primary resonant frequency of clips, the vibration reduction effect of the ring-shaped DVA is analyzed. The results show that the ring-shaped DVA can change the natural frequency of the clip system, reduce the vibration response in the range of the original resonant frequency, and avoid the resonance phenomenon. Finally, the influences of mass ratio, frequency ratio, and damping ratio on the vibration reduction effect are analyzed, and the effectiveness of the parameters design method of ring-shaped DVA proposed in this paper is further proved. The research results can provide methodological support for the anti-breakage design of high-speed railway fastener clips. [ABSTRACT FROM AUTHOR]