• Structural Engineering and Mechanics
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• v.55 no.2
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• pp.413-434
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• 2015

The vibrations caused by metro operation propagate through surrounding soil, further induce secondary vibrations of the nearby underground structures and adjacent buildings. In order to investigate the effects of vibrations caused by metro on use performance of buildings, vibration experiment of Chengdu museum was carried out firstly. Then, the coupling tunnel-soil-structure finite element model was established with software ANSYS detailedly, providing a useful tool for investigating the vibration performances of structures. Furthermore, the dynamic responses and vibration predictions of museum building were obtained respectively by the whole process time-domain analysis and frequency-domain analysis, which were compared with the vibration reference values of museum. Quantitative analyses of the museum building performance were carried out, and the possible tendency and changing laws of vibration level with floors were proposed. Finally, the related vibration isolation measures were compared and discussed. The tests and analysis results show that: The vertical vibration responses almost increased with the increasing of building floors, while weak floors existed for the curve of horizontal vibration; The vertical vibrations were larger than the horizontal vibrations, indicating the vibration performances of building caused by metro were characterized with vertical vibrations; The frequencies of the museum corresponding to the peak vibration levels were around 6~17Hz; The damping effect of structure with 33m-span cantilever on vertical vibration was obvious, however, the damping effect of structure with foundation vibration isolators was not obvious.

• Geomechanics and Engineering
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• v.30 no.3
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• pp.273-280
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• 2022

A certain amount of random vibration excitation to subway track is caused by subway operation. This excitation is transmitted through track foundation, tunnel, soil medium, and ground building to the ground and ground structure, causing vibration. The vibration affects ground building. In this study, the results of ANSYS numerical simulation was used to establish back-propagation (BP) neural network model. Moreover, a back-propagation neural network model consisting of five input neurons, one hidden layer, 11 hidden-layer neurons, and three output neurons was used to analyze and calculate the vertical Z-vibration level of New Capital's ground buildings of Qingdao Metro phase I Project (Line M3). The Z-vibration level under different working conditions was calculated from monolithic roadbed, steel-spring floating slab roadbed, and rubber-pad floating slab roadbed under the working condition of center point of 0-100 m. The steel-spring floating slab roadbed was used in the New Capital area to monitor the subway operation vibration in this area. Comparing the monitoring and prediction results, it was found that the prediction results have a good linear relationship with lower error. The research results have good reference and guiding significance for predicting vibration caused by subway operation.

• Wind and Structures
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• v.29 no.5
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• pp.299-312
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• 2019

Due to the rugged terrain, metro lines in mountain city across numerous wide rivers and deep valleys, resulting in instability of high-pier bridge and insecurity of metro train under crosswind. Compared with the conditions of no-wind, crosswind triggers severer vibration of the dynamic system; compared with the short-pier viaduct, the high-pier viaduct has worse stability under crosswind. For these reasons, the running safety of the metro vehicle traveling on a high-pier viaduct under crosswind is analyzed to ensure the safe operation in metro lines in mountain cities. In this paper, a dynamic model of the metro vehicle-track-bridge system under crosswind is established, in which crosswind loads model considering the condition of wind zone are built. After that, the evaluation indices and the calculation parameters have been selected, moreover, the basic characteristics of the dynamic system with high-pier under crosswind are analyzed. On this basis, the response varies with vehicle speed and wind speed are calculated, then the corresponding safety zone is determined. The results indicate that, crosswind triggers drastic vibration to the metro vehicle and high-pier viaduct, which in turn causes running instability of the vehicle. The corresponding safety zone for metro vehicle traveling on the high-pier is proposed, and the metro traffic on the high-pier bridge under crosswind should not exceed the corresponding limited vehicle speed to ensure the running safety.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.3
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• pp.257-262
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• 2010

Lower tunnels and concrete based tracks are introduced to newly constructed metro lines to reduce the construction and track maintenance fees. But such a lower tunnel together with concrete based track causes higher interior noise of metro trains. It is required that the trains should not only be a transportation media but also be comfortable. So, to lower the metro train's interior noise level, design was made to increase the transmission loss per sectional part. Through such a design, it is expected that about 7 dB(A) of noise level will be reduced compared to that of the conventional train.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.362-367
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• 2010

This paper deals with the correlation between the interior noise and the floor vibration of the train from rolling, impulse and friction in Busan Metro line 3. The correlation is verified by sound and vibration measurement causing friction between the railway and the wheel. If ANC(Active Noise Control) system can reduce 5 dB in below 500 Hz, the sound pressure level of the whole band pass can be reduced about 1.8-4.8 dB in squeal noise. Curve squeal noise is the intense high frequency tonal that can occur when a railway vehicle transverses a curve. The frequency range is from around 500 to almost 20,000 Hz, with noise levels up to about 15 dB in curve.

• Structural Engineering and Mechanics
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• v.76 no.2
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• pp.207-222
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• 2020

Due to the rugged terrain, metro lines in mountain city across numerous wide rivers and deep valleys, resulting in instability of high-pier bridge and insecurity of metro train subjected to fluctuating crosswind. To ensure the safe operation in metro lines in mountain cities, running safety of the metro train over the high-pier bridge under crosswind is analyzed in this paper. Firstly, the dynamic model of the wind-train-bridge (WTB) system is built, in which the speed-up effect of crosswind is fully considered. On the basis of time domain analysis, the basic characteristics of the WTB system with high-pier are analyzed. Afterwards, the dynamic responses varies with train speed and wind speed are calculated, and the safety zone of metro train over a high-pier bridge subjected to fluctuating crosswind in mountain city is determined. The results indicate that, fluctuating crosswind triggers drastic vibration to the metro train and high-pier bridges, which in turn causes running instability of the train. For this reason, the corresponding safety zone for metro train running on the high-pier is proposed, and the metro traffic on the high-pier bridge should be closed as the mean wind speed of standard height reaches 9 m/s (15.6 m/s for the train).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.174-177
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• 2007

In this paper the noise characteristics of metro train is investigated experimentally. It is primarily aimed at observing the squealing noise radiation of each wheel when the vehicle pass the curve sections. This will be used to understand the noise excitation mechanism at the contact area between squealing wheels and rails which induce squeal noise at curve sections. To identify the related key parameters and boundary conditions on-board monitorings of the noise, vibration of the wheel and bogie and displacement behaviour of the wheels and rails have been done. In this paper only noise measurement and results are discussed. From spectrogramms squeal noise due to creepage and noise due to flange contact of the wheels could be identified. At the moment of the curve passing the highest squeal levels are found on the front inner wheel. However since curve noise depends on variable factors more analyses will be followed to identify the squealing wheels and the noise excitation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.817-818
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• 2009

• Explosives and Blasting
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• v.18 no.1
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• pp.59-70
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• 2000

The blasting work to construct a subway in seoul, korea have often cased increased neighbor＇s complaints because of ground vibration. In order to prevent the demage to the stucture it was necessary to predict the level of blasting induced vibration and to determine the maximum charge weigh per delay with an allowable vibration level. The effect of blasting pattem, rock strength and different explosive on the blast-induced ground vibration was studied to determine the maximum charage weight per delay within a given vibration level. The blasting vibration equation from over 100 test data was obtained, V= K(D/W(equation omitted), where the values for n and K are estimated to be 1.7 to 1.5 and 48 to 138 respectively.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.11
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• pp.1113-1120
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• 2012

This paper deals with the analysis of interior noise and low frequency noise characteristic for the Busan citizens to use public transport, Busan Metro Line 3. The interior noise evaluation index, articulation index(AI) is evaluated the lower value about average 22 % in a whole range, this is difficult to have a conversation. Also, noise criteria(NC) curve is partially evaluated as NC-65 below 2000 Hz, space type is evaluated as factories. Another of interior noise evaluation index, preferred speech interference level(PSIL) is evaluated the upper value about average 66 dB(A) in a whole range, this is evaluated to be interrupted. In the case of low frequency noise(20~200 Hz), the measurement of low frequency noise is assessed largely beyond noise criteria of ISO 226. The low frequency noise should be reduced because low frequency noise affects on psychological stress and displeasure although low frequency noise is not recognized by auditory sense. The low frequency noise criteria and guideline will be enacted from now on in Korea.