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.

Site Test and Analysis of Vibration Attenuation Effect of Steel Spring Floating Slab Track

2014 ◽  
Vol 1065-1069 ◽  
pp. 388-392
Author(s):  
Heng Zhang ◽  
Miao Miao Huo ◽  
Lei Meng ◽  
Xiao Shi An
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Vertical Vibration ◽  
Vibration Acceleration ◽  
Steel Spring ◽  
Slab Track ◽  
Vibration Effect ◽  
Acceleration Level ◽  
Vibration Attenuation ◽  
Site Test

Through site test, the paper conducts site test to vertical vibration accelerations when a train passes through steel rails and tunnel walls at a steel spring floating slab track section and a general track section in the tunnel of Yizhuang Line of Beijing Metro. The paper also conducts comparative analysis of the accelerations in time domain and frequency domain. It is shown in results that the vibration acceleration level of the steel spring floating slab track in time domain is reduced by 22 dB in tunnel walls in comparison with the general track; in the frequency domain, the vibration effect is gradually increased with frequency increase and reaches the optimal effect in medium-high frequency. The maximum vibration attenuation quantity of frequency division reaches up to 40 dB; and the maximum Z weighted vibration acceleration level is reduced by 22 dB.

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.

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.

Numerical and Experimental Studies of Pipe Vibration Generated by Elongated Orifice

2016 ◽  
Author(s):  
Wenjie Bai ◽  
Quan Duan ◽  
Zaoxiao Zhang
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Flow Rate ◽  
Vibration Response ◽  
Frequency Range ◽  
Fluctuating Pressure ◽  
Outlet Pressure ◽  
Wall Pressure Fluctuations ◽  
Power Spectral ◽  
Pipe Vibration

Hydraulic tests for elongated orifice-induced wall pressure fluctuations and vibration in pipeline have been carried out. The regulating modes of test system consist of maintaining outlet pressure to increase flow rate and maintaining flow rate to decrease outlet pressure. Both regulating modes would increase the possibility of cavitation within elongated orifice, which has been confirmed by numerical simulation in present study. Statistical characteristics of the fluctuating pressure and structure vibration response have been studied. The standard deviation analyses indicate that the amplitude of fluctuating pressure is mainly determined by flow rate. The power spectral density analyses show that the energy of the fluctuating pressure behind elongated orifice is concentrated in lower frequency range and it can be divided into two parts in this test: the pressure pulsation excited by plunger pump and the random fluctuating pressure produced by elongated orifice’s disturbance. The power spectral density of pipe vibration response shows that the lower frequency of pipe vibration response can be ascribed to the fluctuating pressure behind elongated orifice and the characteristic frequencies corresponding to cavitation within elongated orifice are in the higher frequency range.

FEM/BEM Simulation of Vibroacoustics of a Fluid-Loaded, Stiffened Plate Under Combined Force-Moment Excitation

2000 ◽  
Author(s):  
H. Zheng ◽  
C. Cai ◽  
G. R. Liu ◽  
K. Y. Lam
Keyword(s):  
Numerical Simulation ◽  
Acoustic Radiation ◽  
Normal Modes ◽  
Vibration Response ◽  
Structural Vibration ◽  
Stiffened Plate ◽  
Coupled Modes ◽  
Force Moment ◽  
Surrounding Fluid ◽  
Element Method

Abstract A numerical simulation of structural vibration and acoustic radiation is presented for a finite, fluid-loaded plate reinforced with two sets of orthotropic stiffeners. The attempt is to achieve a physical understanding of the dynamic behaviour and especially the acoustic radiation of the stiffened plate under combined force and moment excitations. Finite element method (FEM) is employed for calculation of the in-vacuo normal modes of the stiffened plate. The coupled modes with a heavy fluid (water), vibration response and acoustic radiation of the plate under given force and/or moment excitation are calculated using boundary element method (BEM). Numerical simulation results are detailed to address the significance of moment in combined force-moment excitations and, more importantly, the cancelling of the combined excitation in both structural vibration response and the associated acoustic radiation into the surrounding fluid.

scholarly journals Study on Vibration Transmission among Units in Underground Powerhouse of a Hydropower Station

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3015 ◽  
Author(s):  
Jijian Lian ◽  
Hongzhen Wang ◽  
Haijun Wang
Keyword(s):  
Low Frequency ◽  
Field Tests ◽  
Vertical Vibration ◽  
Transmission Mechanism ◽  
Structural Vibration ◽  
Hydropower Station ◽  
Fe Model ◽  
Vibration Transmission ◽  
Underground Powerhouse ◽  
Mechanical Models

Research on the safety of powerhouse in a hydropower station is mostly concentrated on the vibration of machinery structure and concrete structure within a single unit. However, few studies have been focused on the vibration transmission among units. Due to the integrity of the powerhouse and the interaction, it is necessary to study the vibration transmission mechanism of powerhouse structure among units. In this paper, field structural vibration tests are conducted in an underground powerhouse of a hydropower station on Yalong River. Additionally, the simplified mechanical models are established to explain the transmission mechanism theoretically. Moreover, a complementary finite element (FE) model is built to replicate the testing conditions for comprehensive analysis. The field tests results show that: (1) the transmission of lateral-river vibration is greater than those of longitude-river vibration and vertical vibration; (2) the vibration transmission of the vibrations that is caused by the low frequency tail fluctuation is basically equal to that of the vibrations caused by rotation of hydraulic generator. The transmission mechanism is demonstrated by the simplified mechanical models and is verified by the FE results. This study can provide guidance for further research on the vibration of underground powerhouse structure.

Development of an Engine System Model for Predicting Structural Vibration

1995 ◽  
Author(s):  
S. H. Sung ◽  
D. J. Nefske
Keyword(s):  
Finite Element ◽  
Narrow Band ◽  
Vibration Response ◽  
System Model ◽  
Structural Vibration ◽  
Octave Band ◽  
Engine System ◽  
Excitation Frequencies ◽  
Engine Components ◽  
Structural Mass

Abstract A finite-element based engine system model is developed for predicting the structural vibration of the engine. The engine system model combines modal models of the major bolted-together sub-structures of the engine, with non-structural mass models of the remaining engine components added to bring the inertial properties to those of the running engine. The model is developed and experimentally evaluated with impact and shaker excitation tests. Comparisons are made of the predicted and measured vibration response for various partially assembled engine configurations, as well as for the fully assembled engine. The comparisons illustrate the accuracy of the model in predicting the narrow-band and one-third octave-band vibration response for excitation frequencies up to 2 kHz.

scholarly journals Ride Comfort Control System Considering Physiological and Psychological Characteristics: Effect of Masking on Vertical Vibration on Passengers

Actuators ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 42 ◽  
Author(s):  
Keigo Ikeda ◽  
Ayato Endo ◽  
Ryosuke Minowa ◽  
Takayoshi Narita ◽  
Hideaki Kato
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Ride Comfort ◽  
Control Method ◽  
Vertical Vibration ◽  
Psychological Characteristics ◽  
Psychological State ◽  
Vibration Acceleration ◽  
Seat Suspension ◽  
Vibration Stress

Active seat suspension has been proposed to improve ride comfort for ultra-compact mobility. Regarding the ride comfort of passengers due to vertical vibration, the authors have confirmed from biometry measurements that reduction of the vibration acceleration does not always produce the best ride comfort for passengers. Therefore, heart rate variability that can quantitatively reflect stress is measured in real time, and a control method was proposed that feeds back to active suspension and confirms its effectiveness by fundamental verification. In this paper, we will confirm the influence of the vibration stress on the psychological state of the occupant by the masking method.

scholarly journals Development of a Frequency-Adjustable Tuned Mass Damper (FATMD) for Structural Vibration Control

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Huaguo Gao ◽  
Congbao Wang ◽  
Chen Huang ◽  
Wenlong Shi ◽  
Linsheng Huo
Keyword(s):  
Damping Ratio ◽  
Tuned Mass Damper ◽  
Vertical Vibration ◽  
Structural Vibration ◽  
Kinematic Equation ◽  
Pedestrian Bridge ◽  
Long Span ◽  
Mass Damper ◽  
Excitation Frequencies ◽  
Simple Assembly

The tuned mass damper (TMD) can be applied to suppress earthquake, wind, and pedestrian- and machine-induced vibration in factory buildings or large span structures. However, the traditional TMD with a fixed frequency will not be able to perform effectively against the frequency variations in multiple hazards. This paper proposed a frequency-adjustable tuned mass damper (FATMD) to solve this limitation of current TMD. The FATMD presented in this paper is composed of a simple assembly consisting of a supported beam with a mass, in which the frequency of the FATMD is changed by adjusting the span of the beam. The kinematic equation of a single degree of freedom (SDOF) structure installed with an FATMD is established to analyze the effect of the damping ratio, mass ratio, and stiffness on the vibration damping. The fundamental frequency of the FATMD at different spans is verified by simulation and experiments. Forced vibration experiments with different excitation frequencies are also conducted to verify the performance of the FATMD. The results show that the proposed FATMD can effectively suppress the vertical vibration of structures at different excitation frequencies, including frequencies at a range higher than what a traditional TMD may not be able to suppress. Additionally, the proposed FATMD is applied to a long-span pedestrian bridge which vibrates frequently due to the walking of pedestrians, the running of escalators, and earthquakes. The numerical results indicate that the FATMD can effectively reduce the vertical vibration of the pedestrian bridge under the excitations of pedestrians, escalators, and earthquakes.

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