Parameterization calculation method for vehicle-induced structural noise of waiting hall under elevated station bridge

Abstract

The invention discloses an elevated station under-bridge waiting hall vehicle-induced structural noise parameterization calculation method, which is characterized by comprising the following steps: S1, dividing the top surface of an elevated station under-bridge waiting hall into areas, acquiring the area of each area, the coordinates of a central point and the time domain vibration acceleration of each central point, and further obtaining the vibration speed; s2, establishing a relationship between the vibration speed and the radiation sound power, and converting the vibration quantity into an acoustic quantity; s3, establishing a relationship between the radiation sound power of each region and the sound pressure radiated to the target point in each region; s4, superposing the sound pressure contributions of the full frequency band and all the areas to obtain total sound pressure; and S5, calculating the structural noise sound pressure level of the target point. Compared with a traditional finite element method and a boundary element method, the method has the advantages that the calculation complexity is remarkably reduced, the efficiency is greatly improved, the full-band calculation precision is improved, the data acquisition threshold is low, and the design period is shortened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of architectural acoustics and vibration engineering, and particularly relates to a parameterized calculation method for train-induced structural noise of a waiting hall under a viaduct station bridge. BACKGROUND

[0002] The waiting hall under the viaduct station bridge is a core node of the high-speed railway network, and the sound environment quality thereof directly affects the comfort and health of passengers. With the increasing popularity of high-speed rail travel, the structural noise problem in the waiting hall is increasingly prominent, which is mainly caused by the vibration energy excited by the dynamic force of the wheel-rail interaction when the high-speed train passes or stops, and the vibration energy is transmitted to the waiting hall through the track, bridge and other structures to cause low-frequency structural noise radiation. Studies have shown that such noise has the characteristics of strong penetration and slow attenuation, and the energy is concentrated in the frequency band below 100 Hz, which is easy to form secondary radiation noise through building components, and significantly reduces the acoustic environment quality of the waiting space. How to accurately predict such noise and propose targeted noise reduction measures has become a key technical challenge to improve the service quality of high-speed rail.

[0003] At present, the prediction of the structural noise of the viaduct station mainly relies on traditional numerical methods such as the finite element method (FEM) and the boundary element method (BEM), which establish a vehicle-track-bridge coupled dynamics model, need to build structural vibration and acoustic grids, and calculate the noise distribution by combining the vibration response. The existing methods have the following shortcomings:

[0004] (1) The number of grids: when calculating the structural noise by using the finite element method, the entire space from the vibrating structure to the target point needs to be divided into grids, and the acoustic elements need to meet the wavelength resolution requirement, usually at least 6-10 elements within one wavelength to accurately capture the sound wave propagation; compared with the finite element method, the boundary element method only needs to divide the surface of the vibrating structure, but also needs to meet the requirement of at least 6-10 elements within one wavelength;

[0005] (2) Grid quality: for the finite element method, in the area close to the vibration source, the grid needs to be encrypted or the boundary layer element needs to be set to capture the local sound wave propagation details; for the boundary element method, the size difference between adjacent elements (such as sudden change > 2 times) needs to be avoided, otherwise it will cause integral singularity or matrix ill-conditioning, increasing the difficulty of solving (such as slow convergence of the iterative method);

[0006] From the above two aspects, the traditional finite element method and the boundary element method have high quality requirements for the model and a large number of element grids when calculating the structural noise.

[0007] (3) Calculation speed: the finite element method needs to discretize the entire structure domain and sound field domain, and the relationship between the number of grids N and the calculation time T is approximately (Proportional to the cube of the number of meshes), especially for large structures like elevated railway stations (generally, the smallest elevated railway station floor slab is 200m × 50m), the number of meshes is extremely large, drastically increasing the demand for computer memory, usually requiring computation at a supercomputing center; the boundary conditions in intermediate steps further increase the time consumption. The boundary element method only requires discretizing the boundary, and the number of meshes N is usually much smaller than that of the finite element method, but the calculation involves full-field integration, and the computation time is long. When the number of grids is greater than 10 5 At this rate, the computation is very slow. In addition, high-frequency noise corresponds to smaller cell sizes (increased mesh count) and requires calculation of more frequency points, so the total computational cost increases exponentially with frequency.

[0008] The aforementioned methods require the construction of complex three-dimensional models, resulting in large computational loads and long processing times. This makes it difficult to quickly provide feedback on noise distribution characteristics during the design phase, leading to delays in structural optimization and noise reduction measures. Furthermore, while the HJ 453-2021 "Technical Guidelines for Environmental Impact Assessment in Urban Rail Transit" referenced in engineering practice uses simplified models to improve computational efficiency, it neglects the impact of multi-factor coupling effects on sound source characteristics and lacks sufficient accuracy in predicting low-frequency structural noise, making it difficult to support refined noise reduction design. Summary of the Invention

[0009] To address the problems existing in the background art, the present invention provides a parameterized calculation method for vehicle-induced structural noise in waiting halls under elevated railway bridges that is computationally efficient, accurate, and easy to implement.

[0010] Therefore, the present invention adopts the following technical solution:

[0011] A method for parametric calculation of vehicle-induced structural noise in waiting halls under elevated railway stations includes the following steps:

[0012] S1, Simplified input parameters: Divide the top surface of the waiting hall under the elevated station bridge into... Get each region area Center point coordinates ( , , And the time-domain vibration acceleration at each center point, thus obtaining the vibration velocity. ;

[0013] S2, establish the relationship between vibration velocity and radiated acoustic power, and convert vibration quantity into acoustic quantity;

[0014] S3, establish the relationship between the radiated sound power of each region and the sound pressure radiated from each region to the target point;

[0015] S4 sums up the sound pressure contributions across the entire frequency band and all regions to obtain the total sound pressure.

[0016] S5, calculate the structural noise sound pressure level at the target point.

[0017] In step S1 above, the top surface of the waiting hall under the elevated station bridge is divided by equal area division or according to the main mode distribution of vibration. When dividing according to the main mode distribution of vibration, the waiting hall floor is regarded as a plate with fixed sides, and the area is divided according to the magnitude of vibration.

[0018] In step S1, the vibration velocity The calculation process is as follows:

[0019] (1) The time-domain vibration acceleration is converted into a frequency-domain acceleration signal by Fourier transform. Frequency domain acceleration The expression is:

[0020] ,

[0021] In the formula, j is the imaginary unit; For real part; is the imaginary part; i = 1 to n; f is the frequency, with a value of 20 to 200 Hz;

[0022] (2) Calculate the vibration velocity :

[0023] .

[0024] In step S2, the formula for calculating radiated sound power is:

[0025] ,

[0026] in, air density; The speed of sound in air; Frequency-dependent acoustic radiation efficiency;

[0027] The acoustic radiation efficiency The expression is:

[0028] ,

[0029] Where m is the surface density of the waiting hall floor slab; It is the critical frequency;

[0030] The critical frequency ,in Let be the material density of the waiting hall floor slab; h be the thickness of the waiting hall floor slab; and D be the bending stiffness of the waiting hall floor slab. Where E is the elastic modulus of the waiting hall floor slab material; The Poisson's ratio is the ratio of the material used for the waiting hall floor slab.

[0031] In step S3, the... Each region in the region is equivalent to a point sound source, and the radiated sound power obtained by S2 is... Calculate the sound source at the target point for each point. sound pressure : ,

[0032] in, ; ; For the first The formula for calculating the phase of vibration acceleration in each region is:

[0033] ,

[0034] Target point Located below the waiting hall floor slab under the elevated station bridge, the location should be selected based on actual needs.

[0035] In step S4, the formula for calculating the total sound pressure level is:

[0036] .

[0037] In step S5, the formula for calculating the structural noise sound pressure level at the target point is:

[0038]

[0039] in, .

[0040] The method of this invention is applicable to rapid calculations in the engineering design phase, and is especially suitable for large building structures such as high-speed railways and urban rail transit hubs.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. This invention is based on an algorithm for the superposition of energy in discretized regions. Compared with the traditional finite element method (FEM) and boundary element method (BEM), it significantly reduces computational complexity and greatly improves computational efficiency. For elevated railway stations, the FEM and BEM typically take 7 days for modeling, 7-10 days for model debugging and calculation, and more than half a month for structural noise calculation, which cannot meet the requirements for rapid response in the engineering design phase. This invention can reduce the number of meshes from tens of thousands to hundreds of regions, calculate structural noise using acoustic radiation efficiency, avoid matrix and integral solving, and use 1 / 3 octave band grouping for calculation, avoiding the drawback of the FEM and BEM requiring more meshes at higher frequencies, greatly reducing the time consumption to 1-2 days.

[0043] 2. This invention uses the vibration data of the center coordinate point of a discrete region and the area to represent the regional energy, preserving the spatial distribution characteristics of vibration and avoiding the low-frequency calculation errors caused by the homogenization assumption in traditional simplification methods. This invention also introduces frequency-dependent sound radiation efficiency, improving the calculation accuracy across the entire frequency band. This invention introduces a complex sound pressure calculation formula, which can accurately reflect the sound wave interference effect and avoid the overestimation problem of directly adding energy.

[0044] 3. This invention simplifies input parameters, standardizes the calculation process, and is compatible with measured vibration data. It only requires the vibration acceleration, coordinates, and area corresponding to the center coordinate point after surface discretization. It does not require complex modal parameters or material constitutive models, thus lowering the data acquisition threshold. The steps are clear and can be directly programmed into an independent tool. It has outstanding engineering usability and is suitable for engineering designers to quickly get started.

[0045] 4. This invention does not rely on commercial software, has controllable usage costs, low maintenance costs, can quickly evaluate the noise reduction effect of different solutions, shortens the design cycle, and has obvious resource savings and cost advantages. Attached Figure Description

[0046] Figure 1 This is a flowchart illustrating the method for parameterizing the structural noise caused by vehicles in the waiting hall under the elevated railway station under the present invention. Detailed Implementation

[0047] The calculation method of the present invention will be described in detail below with reference to the accompanying drawings.

[0048] See Figure 1 The method for parameterizing the vehicle-induced structural noise of the waiting hall under the elevated railway station bridge of the present invention includes the following steps:

[0049] S1, Simplified input parameters:

[0050] To address the drawbacks of the finite element method and boundary element method, such as large mesh size, high mesh quality requirements, and long modeling time, this invention divides the top surface (inner side) of the waiting hall under the elevated railway station bridge into... Each region The number of meshes is much smaller than that of the finite element method or boundary element method; only this... The sound pressure can be calculated from the frequency domain acceleration of each region.

[0051] The methods for dividing the roof area of ​​the waiting hall under the elevated railway station bridge are either equal area division or division based on the distribution of the main vibration modes. The method based on the distribution of the main vibration modes involves treating the waiting hall floor slab as a fixed plate. Since the sound radiation of large structures is generally determined by the first few modes, and these modes reflect the vibration magnitude of different parts of the waiting hall floor slab structure, dividing the area based on vibration magnitude allows for the accurate extraction of the acceleration values ​​reflecting the floor slab vibration.

[0052] The ceiling of the waiting hall under the elevated station bridge is divided into Get each region area Center point coordinates And the time-domain vibration acceleration at each center point, thus obtaining the vibration velocity at each center point. .

[0053] The time-domain vibration acceleration can be obtained through actual measurement or calculated by establishing a time-domain vibration finite element model using MIDAS. The data obtained by both methods are time-domain signals, which need to be converted into frequency-domain acceleration through Fourier transform. Frequency domain acceleration The expression is:

[0054] ,

[0055] In the formula, For real part; It is the imaginary part; The imaginary unit; ; This refers to the frequency, which is typically between 20 and 200 Hz.

[0056] The vibration velocity The calculation formula is:

[0057] .

[0058] S2 establishes the relationship between vibration velocity and radiated acoustic power, converting vibration quantity into acoustic quantity.

[0059] To mitigate the impact of different regional divisions, the area of ​​each region was incorporated into this process. When the area of ​​the divided region is large, the number of divided regions is small; when the area of ​​the divided region is small, the number of divided regions is large. In this case, the area is introduced. As a balancing factor, it can ensure the vibration energy of the entire waiting hall floor. A trend toward stability is more in line with common sense.

[0060] In addition, the structural vibration of the waiting hall under the elevated station bridge is closer to the vibration of the floor slab. Therefore, the radiated sound power of the floor slab is introduced, which makes the calculation results more accurate.

[0061] Radiated acoustic power The calculation formula is as follows:

[0062] ,

[0063] in, air density, The speed of sound in air. For frequency-dependent acoustic radiation efficiency, The calculation formula is:

[0064] ,

[0065] in, The surface density of the waiting hall floor slab; The critical frequency. ,in, The material density of the waiting hall floor slab; The thickness of the waiting hall floor slab; For the bending stiffness of the waiting hall floor slab, ,in The elastic modulus of the waiting hall floor slab material; The Poisson's ratio is the ratio of the material used for the waiting hall floor slab.

[0066] S3, establish the relationship between the radiated sound power of each region and the sound pressure radiated from each region to the target point.

[0067] Will Each region in the region is equivalent to a point sound source, and the radiated sound power obtained by S2 is... Calculate the sound source at the target point for each point. sound pressure ,have:

[0068] in, ; target point ( Located below the waiting hall floor slab under the elevated station bridge, selected according to actual needs; ; For the first The phase of vibration acceleration in each region is calculated using the following formula:

[0069] .

[0070] Because the formula for calculating complex sound pressure has real and imaginary parts, it can reflect the superposition of different sound waves.

[0071] This step establishes the relationship between the radiated sound power of each region and the sound pressure radiated from each region to the target point. This involves introducing... This reflects the mutual interference and influence of sound waves in different regions, which is consistent with the actual situation.

[0072] S4, Sound Pressure Contribution Superposition: The sound pressure contributions of the entire frequency band (20-200Hz) and all regions are superimposed to obtain the total sound pressure, as shown in the following formula:

[0073] ;

[0074] in, It is the center frequency of 1 / 3 octave band within the 20-200Hz range, or the frequency with a step size of 20-200Hz. The frequency, in one embodiment of the present invention =10.

[0075] S5, Calculate the structural noise sound pressure level at the target point: Based on the total sound pressure obtained in S4, and according to the sound pressure level calculation method, the structural noise sound pressure level at the target point is obtained as shown in the following formula:

[0076] ,

[0077] in, .

Claims

1. A parameterized calculation method of train-induced structural noise of an elevated station bridge underpass waiting room, characterized in that, The method comprises the following steps: S1, simplifying input parameters: dividing the top surface of the elevated station bridge waiting hall into areas, obtaining the area , the center point coordinates , , , of each area and the time domain vibration acceleration at each center point, and then obtaining the vibration velocity ; S2, a relationship between vibration velocity and radiated sound power is established to convert vibration into acoustic quantity; S3, a relationship between radiated sound power of each region and sound pressure radiated to a target point by each region is established; S4, sound pressure contributions of all regions in a full frequency band are superposed to obtain total sound pressure; S5, a structure noise sound pressure level of the target point is calculated.

2. The method according to claim 1, wherein the method is characterized by: In S1, the roof of the waiting hall under the elevated station bridge is divided by equal area or according to the distribution of main vibration modes, when divided according to the distribution of main vibration modes, the floor of the waiting hall is regarded as a fixed plate around, and the regions are divided according to the vibration size.

3. The method according to claim 1, wherein the method is characterized by, In S1, the vibration velocity The calculation process is as follows: (1) converting the time-domain vibration acceleration into a frequency-domain acceleration signal by Fourier transform , the expression of the frequency-domain acceleration is ， where j is the imaginary unit; is the real part; is the imaginary part; i = 1 ~ n; f is the frequency, which is 20 ~ 200 Hz; (2) Calculate the vibration velocity : 。 4. The method according to claim 1, wherein the method is characterized by, In S2, the calculation formula of the radiated sound power is: ， wherein, is the air density; is the speed of sound in air; is the frequency dependent acoustic radiation efficiency; The acoustic radiation efficiency The expression for the acoustic radiation efficiency is: ， Wherein, m is the area density of the bus hall floor; is the critical frequency; the critical frequency wherein is the material density of the concourse floor; h is the thickness of the concourse floor; D is the flexural rigidity of the concourse floor, wherein E is the modulus of elasticity of the concourse floor material; is the Poisson's ratio of the concourse floor material.

5. The method according to claim 1, wherein the method is characterized by, In S3, each of the regions is equivalent to a point source, and the radiated sound power obtained by S2 is divided by the area of the region The sound pressure at the target point is calculated for each point source ,​​ wherein ; ; is the vibration acceleration phase of the nth region, and the calculation formula is: ​ ， Target point Located under the floor of the waiting hall under the elevated station bridge, selected according to actual needs.

6. The method according to claim 1, wherein the method is characterized by, In S4, the calculation formula of the total sound pressure is: 。 7. The method according to claim 1, wherein the method is characterized by, In S5, the calculation formula of the structure noise sound pressure level of the target point is: wherein .

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