scholarly journals Analysis of Three-Dimensional Vibration Characteristics of Single-Circle Double-Track Subway Tunnel under Moving Load

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Chunquan Dai ◽  
Mengying Yang ◽  
Quanlei Wang ◽  
Tingzhi Yang ◽  
Kun Jiang
Keyword(s):  
Dynamic Response ◽  
Moving Load ◽  
Compressive Strain ◽  
Three Dimensional ◽  
Urban Rail Transit ◽  
Time Interval ◽  
Subway Tunnel ◽  
Double Line ◽  
Double Track ◽  
The Impact

With the development of urban rail transit, subway lines are becoming more and more denser, the departure time interval is short, and the probability of subway trains meeting is high. The impact of vibration caused by double-line subway meeting on the surrounding environment cannot be ignored. Taking the typical cross-section of a single-circle double-track subway tunnel as an example, a single running scenario and three typical meeting scenarios, namely, 4 s meeting, 6 s meeting, and 8 s meeting scenarios were considered, and a track-tunnel-foundation three-dimensional ABAQUS finite element model was established. The dynamic response of monitoring points at different distances between the center of the track bed and the center line of the track was analyzed. Results showed that due to the consistent load action period, the center acceleration of the track bed increases significantly during the meeting, the main frequency of vibration and the peak value of the 1/3 octave spectrum were increased by about 5 Hz, and the vibration level at the dominant frequency was increased by about 7 dB. The center displacement of the track bed and the peak compressive strain increased significantly under the 4 s meeting and 6 s meeting working scenarios; while the 8 s meeting and 4 s single running scenarios were basically the same, only the action time was doubled. The dynamic response of the 4 working scenarios decreases with the increase of distance, and the attenuation rate gradually decreases and has gradually stabilized within 15–19 m above the vault.

Dynamic response analysis on vibration of ground and track system induced by metro operation

2019 ◽  
Vol 36 (3) ◽  
pp. 958-970 ◽  
Author(s):  
Zhi Ding ◽  
Danwei Li
Keyword(s):  
Dynamic Response ◽  
Response Analysis ◽  
Analysis Model ◽  
Subway Tunnel ◽  
Ground Field ◽  
Element Analysis ◽  
Foundation Soil ◽  
Double Line ◽  
Content Type ◽  
Track System

PurposeThis paper aims to evaluate the dynamic response of surrounding foundation and study the vibration characteristics of track system.Design/methodology/approachA double-line underground coupling analysis model was established, which included two moving train, track, liner and the ground field.FindingsBased on the 2.5D (D is diameter) finite element analysis, the influence of the important factors such as the depth of the subway tunnel, the nature of the foundation soil, the relative position relation of the double tunnel, the subway driving speed on the foundation and the orbital vibration are analyzed in this article.Originality/valueThe results in paper may have reference value for the prediction of train induced vibrations and for the research of dynamic response of ground field.

scholarly journals Structural Dynamic Response of a Shield Tunnel under Aircraft Taxiing Load

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhanyou Luo ◽  
Kuangqin Xie ◽  
Baoping Zou ◽  
Mingyao Jiang ◽  
Wei Zheng
Keyword(s):  
Dynamic Response ◽  
Three Dimensional ◽  
Shield Tunnel ◽  
Transverse Displacement ◽  
Tunnel Structure ◽  
Subway Tunnel ◽  
Structural Dynamic ◽  
Sliding Speed ◽  
Time Space ◽  
Space Effect

Dynamic load is an important factor affecting the safety and stability of subway tunnel structures. To obtain the variation law of shield tunnel structure dynamic response under aircraft taxiing load, a three-dimensional numerical simulation of such tunnel under the action of aircraft taxiing load is performed on the basis of a project involving a shield tunnel orthogonal underpass taxiway. The effects of sliding speed and tunnel depth on the structure of the shield tunnel are also analyzed. The results show that the transverse displacement and acceleration response of tunnel segment exhibit evident time-space effect under the action of aircraft taxiing load. The transverse displacement and arch waist acceleration of the shield segment increase first and then decrease. The transverse displacement of the arch waist reaches its maximum when the aircraft taxis directly above the tunnel. The sliding speed exhibits an evident influence on the dynamic response of shield tunnel structure. The vertical and convergence displacements of tunnel segments increase with the increase in sliding speed. The dynamic response of tunnel structure is significantly affected by the factors of tunnel buried depth. The vertical and convergence displacements of tunnel segments decrease with the increase in tunnel buried depth. Therefore, the safety of the shield tunnel structure can be ensured by controlling the taxiing speed when the aircraft taxis directly above the tunnel. The measures of increasing the buried depth of the tunnel or strengthening the tunnel structure need to be considered when the taxiing speed is large.

scholarly journals The impact of ambient pressure and tunnel inclination angle on the smoke transport in a subway tunnel

2021 ◽  
Author(s):  
Guang Chen
Keyword(s):  
Inclination Angle ◽  
Ambient Pressure ◽  
Three Dimensional ◽  
Concentration Field ◽  
Air Entrainment ◽  
Subway Tunnel ◽  
Environmental Pressures ◽  
Smoke Transport ◽  
Inclination Angles ◽  
The Impact

Abstract The subway tunnel will be built in the plateau where the pressure is relatively low, and the tunnel will tilt at a certain angle due to topographic factors. In order to investigate the smoke transport characteristics of moving subway trains caught fire under different ambient pressures and different tunnel inclination angles, three-dimensional full-scale calculation models of subway trains, two stations and one tunnel are established, and three different environmental pressures (50kPa, 75kPa, 100kPa) and three different tunnel inclination angles (− 1.5 °, 0 °, + 1.5 °) are simulated. The IDDES turbulence model based on kω-sst RANS combined with the overset grid technology is used to simulate the subway train movement and the detailed flow field. The velocity and temperature distribution characteristics and smoke concentration field are studied in detail. The soot density of smoke and temperature increases with reduced ambient pressure due to the weakening of air entrainment and the decreased air density and the influence of ambient pressure on smoke diffusion decreases with the increase of pressure. The longitudinal airflow induced by the stack effect under the negative inclination angle of the tunnel is helpful to prevent the flowing back of smoke.

scholarly journals Influence of Utility Tunnel on the Lower Part of the Existing Double-Track Shield Tunnel in Loess Soil

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Min Yang ◽  
Hongru Li ◽  
Ning Li ◽  
Shun Yang
Keyword(s):  
Shield Tunnel ◽  
Systematic Research ◽  
Distance Ratio ◽  
Double Line ◽  
Maximum Deformation ◽  
Clear Distance ◽  
Utility Tunnel ◽  
Subway Tunnels ◽  
Double Track ◽  
The Impact

The interaction between the double-track shield tunnel and the integrated pipe gallery is complex, and there is still a lack of systematic research. Based on the numerical simulation of the Xi’an case, this paper studies the influence of the construction of the integrated pipe gallery on the deformation characteristics of the existing double-line subway tunnels with different buried depths and clear distances and finds the safe buried depth and clear distance of the tunnel. The results indicated that, in the loess area, the maximum deformation of the existing subway has a linear and inverse relationship with the buried depth and spacing, respectively. Increasing the buried depth can reduce the impact of the upper construction disturbance more than increasing the clear distance ratio. Moreove, under the design conditions of constructing a utility tunnel by the open-cut method, when the buried depth of the tunnel is 4.5 D and the spacing is greater than 4.5 D, or the buried depth is 5.0 D and the spacing is greater than 2.5 D, the combination of subway tunnels can meet the deformation control standards.

scholarly journals Dynamic response of CRTS I double-block ballastless track under three-dimensional temperature and falling-shaft impact loadings

2021 ◽  
Vol 13 (3) ◽  
pp. 168781402110043
Author(s):  
Zhiping Zeng ◽  
Mengxuan Ye ◽  
Fushan Liu ◽  
Abdulmumin Ahmed Shuaibu ◽  
Weidong Wang ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Working Conditions ◽  
Coupling Effect ◽  
Three Dimensional ◽  
Impact Excitation ◽  
Effect Of Temperature ◽  
Large Temperature ◽  
Track Structure ◽  
Ballastless Track ◽  
The Impact

The CRTS I double-block ballastless track under the coupling effect of temperature and falling-shaft impact is more adaptable to actual operation. However, domestic and foreign research has only focused on either temperature or train loadings. In this study, the finite-element method was used to analyze the dynamic response of the double-block ballastless track structure. The results suggests that the displacement and acceleration characteristics of the ballastless track structure under different working conditions change significantly than no temperature gradient. Moreover, the vibration responses at the different working conditions under the impact excitation of a dropping wheelset show that. The findings of this study revealed that temperature has significant impact on falling-shaft which cannot be ignored, consequently it, paper provides referential information for the design, construction, operation and maintenance of the CRTS I double-block ballastless track structure under with large temperature difference.

Orthogonal Analysis on Responses Indexes of Asphalt Pavement

2013 ◽  
Vol 361-363 ◽  
pp. 1523-1526
Author(s):  
Ya Li Ye ◽  
Chuan Yi Zhuang ◽  
Jie Yang ◽  
Yan Zhou
Keyword(s):  
Sensitivity Analysis ◽  
Asphalt Pavement ◽  
Compressive Strain ◽  
Maximum Shear Stress ◽  
Three Dimensional ◽  
Material Design ◽  
Structure Design ◽  
Accurate Analysis ◽  
Orthogonal Analysis ◽  
The Impact

The asphalt layer thickness, base thickness, the modulus of the asphalt layer, base modulus and subgrade modulus are selected as the responses indexes of asphalt. The level of each factor corresponding parameters and test results table are established by orthogonal analysis for four-level table of five factors. This paper took the Shell Designing Software BISAR 3.0 as calculation tool to get the three-dimensional response results of the different kinds of asphalt pavement. Based on results, the course bottom tensile strain of the asphalt layer, subgrade compressive strain and maximum shear stress of asphalt pavement are analyzed by intuitive analysis, variance analysis, and sensitivity analysis. It is found that the sensitivity analysis is a more accurate analysis of the factors of the factor in the level of assessment indicators. Response to the degree of influence of various factors on the pavement mechanics, pavement structure design and material design should be selected according to road type of damage specifications. In accordance with the sensitivity analysis of the impact of factors based on balanced other design specifications.

Vertical Dynamic Response of a Concrete Filled Steel Tube due to Transient Impact Load: Analytical Solution

2016 ◽  
Vol 16 (01) ◽  
pp. 1640014 ◽  
Author(s):  
Xuanming Ding ◽  
Yuming Fan ◽  
Ping Li ◽  
Gangqiang Kong
Keyword(s):  
Analytical Solution ◽  
Dynamic Response ◽  
Wave Equations ◽  
Impact Load ◽  
Separation Of Variables ◽  
Three Dimensional ◽  
Vertical Displacement ◽  
Steel Tube ◽  
Concrete Filled Steel Tube ◽  
The Impact

This paper presents an analytical solution of vertical dynamic response of a concrete-filled steel tube (CFST) due to transient impact loading. Both the concrete and steel are modeled by linear elastic material. The impact load is simulated by a semisinusoidal impulse. Three-dimensional (3D) wave equations those considering the vertical displacement are established. By combining the initial and boundary conditions, the frequency-domain analytical solution of displacement is deduced by Laplace transformation and separation of variables methods. The time-domain dynamic response is then obtained by numerical inverse Fourier transformation (IFT). Numerical examples are presented to verify the validity of the analytical solution developed in this study. The results indicate that the analytical solution proposed in this study shows good consistence with the existing solutions.

Impact Analysis of Foundation Pit Excavation on the Deformation of Nearby Subway Tunnel

2014 ◽  
Vol 935 ◽  
pp. 233-236
Author(s):  
Hui Shen ◽  
Jin Feng Bi ◽  
Tong Qi Ping
Keyword(s):  
Impact Analysis ◽  
Simulation Analysis ◽  
Three Dimensional ◽  
Subway Tunnel ◽  
Foundation Pit ◽  
Soil Subsidence ◽  
Maximum Value ◽  
Margin Of Safety ◽  
Design Proposal ◽  
The Impact

Bracing of foundation pit design proposal based on the excavation near a block of Suzhou Rail Transit Line 1 is used to build a subway tunnel-pit-envelope three-dimensional computational model, which is analyzed by FLAC3D, software for numerical simulation analysis, to evaluate the impact of the foundation pit excavation on the deformation of the subway tunnel. The calculated results show that: when the pit is excavated to the bottom, the deformation of the tunnel achieves the maximum value, 0.6mm of y direction and 6.54mm of z direction. The pipelines with shallow depth are subject to the deformation caused by the soil subsidence back of the envelope, whose maximum value has reached 7.6mm beyond the control standards. In terms of the deformation of the subway tunnel structure, the deformation can meet the control requirements, and have a certain margin of safety.

Dynamic analysis of railway with locally continuous supported superstructures

2019 ◽  
Vol 36 (9) ◽  
pp. 3047-3069
Author(s):  
Muzaffer Metin ◽  
Arif Ulu ◽  
Ozgur Demir ◽  
Aytac Arikoglu
Keyword(s):  
Dynamic Response ◽  
Moving Load ◽  
Damping Ratio ◽  
Time Integration ◽  
Three Dimensional ◽  
Equation System ◽  
Solution Technique ◽  
Vehicle Speed ◽  
Content Type ◽  
Three Dimensional Finite Element

Purpose In this study, a railway superstructure is modeled with a new approach called locally continuous supporting, and its behavior under the effect of moving load is analyzed by using analytical and numerical techniques. The purpose of the study is to demonstrate the success of the new modeling technique. Design/methodology/approach In the railway superstructure, the support zones are not modeled with discrete spring-damping elements. Instead of this, it is considered to be a continuous viscoelastic structure in the local areas. To model this approach, the governing partial differential equations are derived by Hamilton’s principle and spatially discretized by the Galerkin’s method, and the time integration of the resulting ordinary differential equation system is carried out by the Newmark–Beta method. Findings Both the proposed model and the solution technique are verified against conventional one-dimensional and three-dimensional finite element models for a specific case, and a very good agreement between the results is observed. The effects of geometric, structural, and loading parameters such as rail-pad length, rail-pad stiffness, rail-pad damping ratio, the gap between rail pads and vehicle speed on the dynamic response of railway superstructure are investigated in detail. Originality/value There are mainly two approaches to the modeling of rail pads. The first approach considers them as a single spring-damper connected in parallel located at the centroid of the rail pad. The second one divides the rail pad into several parts, with each of part represented by an equivalent spring-damper system. To obtain realistic results with minimum CPU time for the dynamic response of railway superstructure, the rail pads are modeled as continuous linearly viscoelastic local supports. The mechanical model of viscoelastic material is considered as a spring and damper connected in parallel.

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