scholarly journals Vibration Response Characteristics and Application of Existing Railway Subgrade

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Junyun Zhang ◽  
Zhuoling He ◽  
Siyuan Chen ◽  
Le Zhang
Keyword(s):  
Vertical Vibration ◽  
Vibration Response ◽  
Disease Assessment ◽  
Horizontal Distance ◽  
Acceleration Response ◽  
Vibration Acceleration ◽  
Response Characteristics ◽  
Attenuation Law ◽  
Before And After ◽  
Research Studies

The existing conventional methods of subgrade disease assessment are not suitable for the existing lines. There are many research studies on the vibration response and attenuation law of the railway subgrade, but few research studies focus on the vibration response and attenuation law caused by the weak subgrade. In this study, vibration response tests were carried out at different positions and depths of the subgrade before and after reinforcement improvement. The results show that vibration response near the ballast is obvious, and it attenuates with the increase of the horizontal distance from the rail; the vibration acceleration response of the subgrade after reinforcement changes greatly; the vibration response curve of the reinforced section is spindle shaped, and the vertical vibration acceleration response attenuates obviously at the depth of 6.5 m, only about 10% to 30% of the surface; the vibration acceleration of the subgrade with reinforcement at the depth of 4.5 m attenuates to 60% of the surface; the vibration acceleration of the subgrade without reinforcement at the depth of 4.5 m attenuates to 50%–60% of the surface.

scholarly journals Influence Factors of Vibration Response on Supporting-Thrusting System of Tunnel Boring Machine

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yongbing Mei ◽  
Yimin Xia ◽  
Laikuang Lin ◽  
Yongliang Cheng ◽  
Cong Qian
Keyword(s):  
Influence Factors ◽  
Tunnel Boring Machine ◽  
Vertical Vibration ◽  
Surrounding Rock ◽  
Vibration Response ◽  
Main Beam ◽  
Support Pressure ◽  
Vibration Acceleration ◽  
Tunnel Boring ◽  
Input Load

A supporting-thrusting system is the main load-bearing component of a tunnel boring machine (TBM) and the centralization of vibration response under TBM working. This study combines the structure and working principle of the supporting-thrusting system. Based on the vibration theory and test results at a construction site, the main influence factors of the vibration response of the supporting-thrusting system are the main beam structure, the characteristic parameters of advance cylinder, and the support pressure to surrounding rock. Under the different influence factors, the vibration response of the supporting-thrusting system is calculated and analyzed via computer simulation. The results indicate that, under the equivalent input-load on the TBM and increase in the length of the front main beam, the vibration acceleration at the front area of the TBM increases. The change rate of vertical vibration will be maximum, while the vibration acceleration at the rear area of TBM decreases. When the structure size of the thrusting cylinder increases, the vibration acceleration on the main beam decreases and those of the gripper shoe and saddle frame increase. However, the response to the axis vibration is the most sensitive. As the horizontal support pressure to the surrounding rock increases, the vibration acceleration on supporting-thrusting system decreases. When the level of support pressure exceeds 1.6e4 kN, the vibration acceleration changes gradually. These results provide a reference for designing and operating TBM parameters.

Detection of Rail Fastener Conditions Using Time-Frequency Entropy Based on Orthogonal Empirical Mode Decomposition

2013 ◽  
Vol 333-335 ◽  
pp. 1708-1712 ◽  
Author(s):  
Chong Liu ◽  
Li Hua Zhang ◽  
Tong Qun Ren ◽  
Jun Sheng Liang ◽  
Da Zhi Wang ◽  
...  
Keyword(s):  
Empirical Mode Decomposition ◽  
Frequency Spectrum ◽  
Vibration Signal ◽  
Vertical Vibration ◽  
Intrinsic Mode Functions ◽  
Acceleration Response ◽  
Vibration Acceleration ◽  
Time Frequency ◽  
Mode Decomposition ◽  
Outdoor Experiment

A method based on OEMD (Orthogonal Empirical Mode Decomposition) and the theory of time-frequency entropy was applied to detect different rail fastener conditions. The original vertical vibration acceleration response of rail under different fastening conditions was obtained from outdoor experiment. The OEMD method was used to get orthogonal IMFs (Intrinsic Mode Functions) of the original vibration signal. The Hilbert time-frequency spectrum was then obtained based on the orthogonal IMFs and corresponding entropy was calculated and compared. The results show that the method is available to detect different rail fastener conditions.

scholarly journals Attenuation Law of Train-Induced Vibration Response of Subgrade in Beijing–Harbin Railway

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Ziyu Wang ◽  
Xianzhang Ling ◽  
Lina Wang ◽  
Yingying Zhao
Keyword(s):  
Field Experiments ◽  
Damping Ratio ◽  
Vibration Response ◽  
Vibration Level ◽  
Attenuation Curve ◽  
Vibration Acceleration ◽  
Negative Exponential Function ◽  
Attenuation Law ◽  
Vehicle Load ◽  
Environmental Vibration

To investigate environmental vibration in the case of railway subgrade in seasonally frozen regions, field experiments were conducted on the Beijing–Harbin railway subgrade of China in autumn and winter. Vibration acceleration and vibration level attenuation law were analysed based on monitoring results. Accordingly, the influence of the subgrade freeze-thaw states, vehicle load, train formation, and running speed on the subgrade surface environmental vibration was analysed. The vibration response of the subgrade decreased with an increase in the distance from the track. The attenuation curve of the vibration acceleration can be fitted using the negative exponential function, and the attenuation curve of the vibration level can be fitted using the linear function. Additionally, the subgrade vibration response during the frozen period was greater than that during the unfrozen period owing to increased strength and rigidity and decreased damping ratio after subgrade freezing, which increased the vibration response. Moreover, the vibration intensity of the subgrade increased with increase in the vehicle load and formation and decreased with an increase in the driving speed within a particular speed range. The findings of this study provide an objective basis for railway subgrade design and disaster assessment in cold regions of China.

Experimental Study on Controlling Rail Corrugation by Tuning Rail Damper

2014 ◽  
Vol 587-589 ◽  
pp. 1002-1006
Author(s):  
Heng Zhang ◽  
Liang Jiang ◽  
Yu Jie Li ◽  
Lei Meng ◽  
Xiao Shi An
Keyword(s):  
Experimental Study ◽  
Decay Rate ◽  
Vertical Vibration ◽  
Vibration Acceleration ◽  
Rail Corrugation ◽  
Before And After ◽  
Speed Up ◽  
Vibration Wave ◽  
And Control ◽  
Rail Damper

At a serious rail corrugation line along Beijing metro Yi-zhuang line, one experiment of controlling rail corrugation has done. Based on the test and analysis of rail vibration decay rate, rail surface roughness and vibration acceleration on the rail and track bed before and after install TRD, it is concluded that install TRD on rail waist could improve rail damping, enhance rail vibration decay rate, speed up vibration wave propagation decay in the rail, reduce the vertical vibration of rail and track bed, and control the development of rail corrugation.

Field Measurement and Analysis of Vibration Response in the Metro Shield Tunnel with Straight Joint

2013 ◽  
Vol 838-841 ◽  
pp. 1363-1369
Author(s):  
Ming Yu Li ◽  
Yuan Cheng Guo
Keyword(s):  
Response Time ◽  
Vertical Vibration ◽  
Vibration Response ◽  
Structural Vibration ◽  
Shield Tunnel ◽  
Frequency Range ◽  
Vibration Acceleration ◽  
Steel Spring ◽  
Measurement And Analysis ◽  
Standard Block

Appling the M8 as the monitor objects and choosing the single-round shield tunnel with or without the steel spring floating slab and the DOT shield tunnel with straight joint as the research objects, the vertical vibration response of the track bed and the standard block in different conditions was compared. The peak vibration acceleration of two measuring points and vibration response time of the standard block in the DOT is smaller compared with the DOT and the single-round shield tunnel when a single train is through the monitoring section. Vibration response time and intensity of the DOT structure is increasing with two trains intersection. Compared to the other two shield tunnels, structural vibration response of the single-round shield tunnel is significantly decreased by the isolation effect of steel spring floating slab. For the vibration acceleration of the track bed and the standard block in the three types of shield tunnels, spectrum range is 0Hz~150Hz, and peak acceleration is in the same frequency range, which is 35Hz~70Hz. Peak vibration acceleration of the track bed is greater than that of the standard block.

Flow Passage Modification and Experimental Verification of a Multi-Stage Centrifugal Pump

2013 ◽  
Vol 753-755 ◽  
pp. 2766-2769
Author(s):  
Quan Zhang ◽  
Zhi Jun Shuai ◽  
Pan Zhou ◽  
Wan You Li
Keyword(s):  
Centrifugal Pump ◽  
Cfd Simulation ◽  
Acceleration Response ◽  
Vibration Acceleration ◽  
Flow Passage ◽  
Fluid Field ◽  
Multi Stage ◽  
Through Flow ◽  
Seat Vibration ◽  
Velocity Pressure

In this paper the seat vibration acceleration response was reduced through flow passage modification of the centrifugal pump which could decrease the fluid excitation of the pump. CFD simulation technology was applied to optimize the fluid field of the multi-stage centrifugal pump, and then the velocity, pressure fluctuation and fluid excitation were concerned to investigate the effect of optimization. Finally, the influence of fluid field modification on the seat vibration response was verified experimentally.

scholarly journals The Effect of Soil Reinforcement on the Stress and Strain Field Around Underground Square-Shaped Areas and its Internal Lining Efforts in Urban Areas

2018 ◽  
Vol 4 (11) ◽  
pp. 2756 ◽  
Author(s):  
Alireza Darvishpour ◽  
Asadollah Ranjbar ◽  
Amirmohammad Amiri
Keyword(s):  
Urban Areas ◽  
Underground Structure ◽  
Physical Modelling ◽  
Soil Reinforcement ◽  
Soil Parameters ◽  
Stress And Strain ◽  
Horizontal Distance ◽  
Underground Structures ◽  
Finite Element Software ◽  
Before And After

The passage of underground structures from the bottom of the structures on the ground causes a change in the stresses and strains created in the structure as well as the soil environment surrounding the tunnel due to the existence of an interaction between these two sides. In this way, the existence of the surface structure leads to a change in the strain and stress conditions around the tunnel, and in contrast, the tunnel also leads to a change in the stress and settlement around the structures. Therefore, such a reciprocal behavior is very important. In this research, with the help of Abaqus finite element software, two main possible conditions are considered: the creation of an underground structure in the presence of the superstructure, as well as the reverse state of the concept of constructing a building in the state in which the underground structure already exists. One of the subjects studied in this research is the physical modelling effect of the structure, rather than the effect of its wide load on the ground. Other parameters considered in this research are the number of story, the depth of the tunnel, the width of the tunnel, the thickness of the lining, the effect of changes in the soil parameters in the depth and the horizontal distance of the tunnel center from the building center. The results of this research are validated based on the results obtained by other researchers. According to the results obtained in this research, by the increase of the distance between the tunnel center and structure center and depending on the stiffness of the tunnel lining, significant asymmetric stresses are created in the superstructure. The construction of the structure before and after the tunnel construction can affect the unsymmetrical settlement of the structure The stress and strain created in the lining of the tunnel and the surrounding area are also different due to the amount of mobilized force in the reinforcements.

Optimization of Vehicle Powertrain Mounting System and its Performance

2013 ◽  
Vol 441 ◽  
pp. 580-583
Author(s):  
Gong Yu Pan ◽  
Xin Yang ◽  
You Yan
Keyword(s):  
Vibration Isolation ◽  
Dynamics Model ◽  
Acceleration Response ◽  
Idle State ◽  
Decoupling Method ◽  
Before And After ◽  
Vibration Transmissibility ◽  
Six Degree Of Freedom ◽  
Vibration Isolation Performance ◽  
Isolation Performance

In order to solve the vibration problem of diesel engine powertrain assembly at its idle state, a six degree-of-freedom dynamics model of the powertrain mounting system is established and a optimization based on Adams/View is applied to simulation and analysis on the powertrain mounting system with energy decoupling method. The results show that the optimized repositioning mounts installation position can effectively improve decoupling rate in main vibration directions of mounting system. Based on this, the vibration transmissibility and acceleration response before and after optimization are simulated. The results show that the optimized engine mounting system makes a great improvement of vibration isolation performance.

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