scholarly journals Model Test Study on the Influence of Train Speed on the Dynamic Response of an X-Section Pile-Net Composite Foundation

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Shanshan Xue ◽  
Yumin Chen ◽  
Hanlong Liu
Keyword(s):  
High Speed ◽  
Dynamic Stress ◽  
Composite Foundation ◽  
Vibration Velocity ◽  
Distribution Characteristics ◽  
Vibration Acceleration ◽  
Foundation Soil ◽  
Dynamic Displacement ◽  
Train Speed ◽  
Train Loading

Based on a large-scale X-section pile-net composite foundation model, we experimentally studied the dynamic characteristics of the pile-net composite foundation under a high-speed railway train load; analyzed the distribution characteristics of the dynamic stress, dynamic displacement, speed, and acceleration of the foundation soil under different train speeds; and investigated the vibration response of the track subgrade foundation system, as well as the distribution characteristics and attenuation pattern of the dynamic stress inside the subgrade foundation under cyclic train loading. The following results are obtained. The peak vertical vibration speed and the peak acceleration attenuate by 90% and 62.5%, respectively, after passing through the embankment. The vibration velocity increases linearly with the train speed; the ratio of the peak dynamic soil stresses at the top of the piles and between the piles is approximately 3.4. The change in train speed does not have a large influence on the peak dynamic displacement or peak dynamic soil stress. The peak spectral vibration acceleration caused by the train loading is located within the range of medium-to-low-frequency vibrations, and the characteristic frequency corresponds to the passing frequency of the bogies and carriages; as the train speed increases, the peak spectral vibration acceleration increases, and the high-frequency components increase significantly.

The Effect of CFG-Pile Caps and Cushion to Stability of Embankment

2011 ◽  
Vol 287-290 ◽  
pp. 797-800
Author(s):  
Zhen Hua Wu ◽  
Jian Yi Yuan
Keyword(s):  
High Speed ◽  
Stress Ratio ◽  
Dynamic Stress ◽  
Vertical Section ◽  
Composite Foundation ◽  
High Speed Railway ◽  
Dynamic Displacement ◽  
Wide Range ◽  
Pile Caps ◽  
Cfg Pile

Subgrade diseases are exposed more and more serious with raising speed of existing railway in wide range. Dynamic numerical simulation had been done to analyze the effect of CFG-pile caps and cushion in composite foundation with CFG-pile in low embankment of Beijing-Shanghai high-speed railway. Distribution rules of dynamic displacement and dynamic stress of the subgrade surface and ground surface on the cross section, attenuation rules of dynamic response and dynamic stress ratio between pile and soil on the vertical section were studied. It shows that the dynamic stress of pile and soil generally attenuates in depth and attenuation of dynamic stress ratio between pile and soil mostly concentrates in the scope of 10m beneath the ground and dynamic stress caused by train load is undertaken by the pile. Moreover the scheme of CFG-pile with no pile caps and rigid cushion scheme is superior to that of pile caps and flexible cushion scheme for enhancing dynamic stability and reducing dynamic displacement and stress in low embankment. It will be instructive to control design and construction for the low embankment in Beijing-Shanghai high-speed railway.

scholarly journals Experimental and Numerical Study of the Dynamic Response of XCC Pile–Raft Foundation under High-Speed Train Loads

2021 ◽  
Vol 11 (19) ◽  
pp. 9260
Author(s):  
Qiang Fu ◽  
Jie Yuan
Keyword(s):  
Dynamic Response ◽  
High Speed ◽  
Large Scale ◽  
Numerical Study ◽  
Soft Soil ◽  
Composite Foundation ◽  
Scale Model ◽  
Vibration Velocity ◽  
Wheel Load ◽  
Foundation Soil

A series of dynamic large-scale model tests and three-dimensional finite element analyses were conducted to investigate the dynamic response of track embankment and XCC pile-raft composite foundation in soft soil for a ballastless high-speed railway under moving train loads. The results indicate that the vibration velocity obtained from the FE numerical simulation agrees well with that from the model test in vibration waveform, amplitude, and frequency characteristics. The peak values corresponding to the passing frequency of train carriage geometry (lc = 25 m), bogie (lab = 7.5 m), and axle distance (lwb = 2.5 m) respectively reflect the characteristic frequencies of the train compartment, adjacent bogie, and wheel load passing through. The peak velocity significantly depends on the distance from the track center in the horizontal direction, of which the attenuation follows the exponential curve distribution. The vibration velocities decrease rapidly within embankment, show a vibration enhancement region from raft to the 1 m depth of foundation soil, then decreases gradually along the subsoil foundation, to a very low level at the bottom of the subsoil, which is much lower than that at the track slab and roadbed. The pile-raft composite foundation can reduce the vibration level effectively and improve the safety of trains running in soft soil areas.

Analysis of Shock Resistance on GWC6066 Marine Gearbox

2014 ◽  
Vol 602-605 ◽  
pp. 135-138
Author(s):  
Wen Liu ◽  
Teng Jiao Lin ◽  
Ze Yin He
Keyword(s):  
Dynamic Stress ◽  
Strength Criterion ◽  
Element Model ◽  
Vibration Velocity ◽  
Vibration Acceleration ◽  
Dynamic Finite Element ◽  
Spring Element ◽  
Equivalent Time ◽  
Shock Resistance ◽  
Resistance Performance

The dynamic finite element model of entire gearbox, including gears, shafts, bearings and gearbox housing was established by using the truss element, spring element and tetrahedral element at first. Then the shock spectrum of GWC6066 gearbox was gotten according to German specification BV043/85. After the shock spectrum converted into equivalent time-domain acceleration curve, the vibration velocity, vibration acceleration and dynamic stress of GWC6066 gearbox under the double half-sine acceleration shock excitation were simulated. At last, the shock resistance performance of gearbox was analyzed combining with the strength criterion.

Dynamic Response Analysis on Efficacy of CFG-Pile in Different Height Embankment

2011 ◽  
Vol 311-313 ◽  
pp. 145-148
Author(s):  
Jian Xiang
Keyword(s):  
Dynamic Response ◽  
Dynamic Stability ◽  
High Speed ◽  
Stress Ratio ◽  
Dynamic Stress ◽  
Ground Surface ◽  
High Speed Railway ◽  
Dynamic Displacement ◽  
Embankment Height ◽  
Cfg Pile

In order to analyze the effect of embankment height to dynamic stability, Cross-section in the Beijing-Shanghai high-speed railway is chosen and the numerical simulation calculation method is applying. Distributing rules of dynamic displacement and dynamic stress of the subgrade surface and ground surface, attenuation rules of dynamic response and dynamic stress ratio between pile and soil on the vertical section were studied. It shows that the dynamic stress of pile and soil generally attenuates in depth and attenuation of dynamic stress ratio between pile and soil mostly concentrates into the scope of 10 meters beneath the ground. Moreover, with the increment of embankment height and attenuation of dynamic stress in direct proportion to the depth, the dynamic stress transferring to ground surface decrease and the dynamic displacement of ground surface minish. As a result, the scheme of CFG-pile with 3m scheme is superior to that of 2m scheme for enhancing dynamic stability and reducing dynamic displacement and stress in low embankment. It will be instructive to control design and construction for the low embankment in Beijing-Shanghai high-speed railway.

Dynamic response of soft soils in high-speed rail foundation: in situ measurements and time domain finite element method model

2019 ◽  
Vol 56 (12) ◽  
pp. 1832-1848 ◽  
Author(s):  
Yiqun Tang ◽  
Qi Yang ◽  
Xingwei Ren ◽  
Siqi Xiao
Keyword(s):  
Dynamic Response ◽  
Time Domain ◽  
High Speed ◽  
In Situ Measurements ◽  
Vertical Acceleration ◽  
High Speed Rail ◽  
Foundation Soil ◽  
Train Speed ◽  
The Time Domain

The dynamic response of soil to vibrations induced by moving trains has been widely studied using in situ measurements. However, few in situ tests have been conducted to measure the resulting vibration of foundation soils, especially for the foundation of high-speed rail (HSR) in a soft area. In this study, a number of field experiments were conducted on Shanghai–Hangzhou HSR in a suburb of Shanghai, China. The testing instruments were installed in foundation soils just beneath the HSR track to measure the vibration induced by trains moving at different speeds. Test results show the frequencies of foundation soil vibration are characterized by the train speed and geometrical features of the trains and slab track. In the frequency domain, the dominant frequency bands for vertical acceleration, velocity, and displacement of foundation soil decrease successively. In the time domain, the magnitudes of vibration levels at different locations in a soil foundation decrease gradually with increasing distance from the track. Furthermore, higher train speed can result in higher vibration level. Based on the field conditions, a three-dimensional dynamic finite–infinite element model is developed in the time domain. It shows the model is capable of capturing the primary characteristics of train-induced vibration in the field.

scholarly journals Analyzing vibration parameters of a modern high-speed engine during operation

2021 ◽  
Vol 2061 (1) ◽  
pp. 012056
Author(s):  
V V Gerasidi ◽  
A V Lisachenko
Keyword(s):  
Experimental Research ◽  
High Speed ◽  
Vibration Velocity ◽  
Frequency Range ◽  
Vibration Acceleration ◽  
Vibration Displacement ◽  
Black Sea Region ◽  
High Speed Engine ◽  
Vibration Parameters ◽  
Speed Engine

Abstract The paper presents results of experimental research into vibration parameters of a modern electronic control-enabled main high-speed engine, Caterpillar CAT 3516B as obtained during a running trial of a sea tug. CAT 3500 series Caterpillar high-speed engines are extensively used in sea tugs; there are about 40 units installed in vessels operating in the Azov and Black Sea region. The research technique involved measurement of vibration displacement, vibration velocity, vibration acceleration at an engine and its turbocharger components. The conducted experimental research has shown that in order to evaluate the technical state of an engine, it is necessary to measure vibration displacement and vibration velocity in a frequency range from 1 to 1000 Hz at 0.1 Hz intervals. For turbochargers, the vibration acceleration shall be measured in a frequency range from 1 to 15000 Hz at 1 Hz intervals. The results of the experimental research allowed determining necessary conditions for measurement of vibration parameters of Caterpillar CAT-3500 series modern high-speed engines commonly used in sea tugs. The experimental research into vessel installations by in-place diagnostics at operating sea-going vessels forms a foundation of an autonomous ship control system.

The Vibration Analysis and Modal Experimental Study of High Speed Motorized Spindle

2011 ◽  
Vol 291-294 ◽  
pp. 3078-3082 ◽  
Author(s):  
Jie Meng
Keyword(s):  
High Speed ◽  
Natural Frequencies ◽  
Resonance Region ◽  
Vibration Velocity ◽  
Maximum Speed ◽  
Test Bed ◽  
Vibration Testing ◽  
Vibration Acceleration ◽  
Motorized Spindle ◽  
Testing Method

Vibration testing and modal experiment under the different speed are carried out to the high speed motorized spindle whose maximum speed is 60 000 rpm. Time domain waveform and spectrum of motorized spindle’s radial vibration acceleration are obtained under the unload state. Through calculating and analyzing, the vibration velocity and the testing point which generates the maximum vibration velocity are found out. Then motorized spindle is validated whether it accords with the requirements of high-precision manufacture. And the correctness of the vibration testing method is also verified. Primary reasons of the motorized spindle’s vibration are put forward. The first five steps natural frequencies of motorized spindle test-bed are gained by appropriate ways to checkout if the test-bed in the resonance region.

The Dynamic Analysis of Soft Soil Subgrade in High-Speed Railway Strengthened by PHC Pile

2014 ◽  
Vol 1030-1032 ◽  
pp. 908-911 ◽  
Author(s):  
Zhen Hua Pan ◽  
Kong Ming Yan ◽  
Jin Biao Wu ◽  
Zhe Wang ◽  
Wei Ming Liao
Keyword(s):  
Prestressed Concrete ◽  
High Speed ◽  
Dynamic Stress ◽  
Soft Soil ◽  
Time History ◽  
Composite Foundation ◽  
High Speed Train ◽  
High Speed Railway ◽  
Soft Soil Area ◽  
Soil Area

The combination of PHC pile (prestressed concrete pile) with geogrid to reinforce the foundation has been widely used in high-speed railway, and the response of dynamic stress under the high-speed train is worth studying. By using Midas/GTS NX software to establish a 3-D model of pile-net composite foundation in one section of Hangzhou - Shenzhen line, the influence of pile-net composite foundation generated by high-speed train is studied. Moreover, this paper also studies the distribution and propagation of dynamic stress generated by train load in soft soil area. The results show that the dynamic stress reducing quickly in the embankment structure and the time –history curve of the dynamic stress behaves differently along the depth. With the depth increasing, there is phenomenon of peak superposition in the time-history curve of the vertical dynamic stress. In the meanwhile, the PHC pile is the main structure to propagate and sustain the dynamic stress in soft soil area, and with the tendency of ‘large in the middle, small on both ends’.

Numerical Analysis of Ground Vibration Induced by High-Speed Train on Viaduct

2011 ◽  
Vol 66-68 ◽  
pp. 937-943
Author(s):  
Zheng Hui Li ◽  
Yan Mei Cao ◽  
He Xia
Keyword(s):  
Numerical Analysis ◽  
Pile Foundation ◽  
High Speed ◽  
Numerical Models ◽  
Damping Ratio ◽  
Ground Vibration ◽  
Bridge Pier ◽  
High Speed Train ◽  
Foundation Soil ◽  
Train Speed

In order to study the ground vibrations induced by high-speed train passing on viaduct, two FEM sub-models, the train-bridge-pier model and the pile foundation-soil model, are established by means of the software of ANSYS. The effectiveness of the numerical models is tested and verified by comparing with other existed results. Moreover, the influences of different train speed and the damping ratio of soil on ground vibration are analyzed.

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