| Noise barrier is one of the effective facilities to reduce the high-speed railway noise. With the development of high-speed railway in China, it is more and more widely applied. When the high-speed train passed, the fatigue fail may occur under the repeating fluctuating pressure. The current research on noise barrier is still far from satisfying the requirements of practical engineering. And structural design still stay on the idea of using the maximum of fluctuating pressure multiplied by dynamic load amplification factor as the average pressure, which often results in a large safety factor and a waste of resources. In order to achieve the objectives of high-speed railway environmental protection and sustainable development, a study on the impact of the train fluctuating pressure to the noise barrier strength and fatigue properties is needed.By using the viscous, compressible, unsteady fluid flow equations and the standard k-ε turbulence model to simulating the 3-D flow field when trains passed noise barrier, the law of the fluctuating pressure distribution on the surface of noise barrier was obtained, also the functional relationship of the aerodynamic force between the speed of train and the distance of noise barrier to the track centerline. With reference to the relevant standard, a noise barrier solid structural model was established. According to the dynamic theory, modal analysis was done as well as strength calculation under various conditions by using the unidirectional fluid and solid interaction technique on the noise barrier solid structural model. The law of the noise barrier deformation, the equivalent stress time history curve, and the empirical formula to estimate the maximum of equivalent stress and deformation with the speed of train and the distance of noise barrier to the track centerline were obtained. And the static strength check was done by the time. According to the equivalent stress curve, stress spectrum was obtained by rain flow count method. With S-N curve and the linear cumulative damage theory, the fatigue life prediction of noise barrier and its fatigue properties analysis were done.The results indicated as follow:1. The fluctuating pressure of train on noise barrier is a surface load varying with time and space, whose magnitude depends on the speed of train and the distance from noise barrier to the track centerline. Along the height direction of noise barrier, it decreases from bottom to top inside and increases outside. The aerodynamic force per unit length is almost proportional to the square of speed while negative exponential relationship with the distance from noise barrier to the track centerline.2. The natural frequency of noise barrier is far greater than the frequency of fluctuating pressure, so the noise barrier won’t resonate when the train passes. Under the action of fluctuating pressure, the H-steel column experienced bend and torsion deformation simultaneously. Under the function of head-waves, the column bend away from the train first and then close to, and the torsion changes from counterclockwise to clockwise then reverse again as seen in the direction from the top view. While the bend and torsion change their directions oppositely when the tail-waves come. The equivalent stress changes as four pulse, and the first one is max which is proportional to the square of speed. And it is far below the ultimate strength, so the static strength damage will not occur.3. Although the H-steel column has infinite life within the scope of calculated conditions, the fatigue safety factor is less than 1.5 with taking the train crossing into account when the speed is 350km/h and the distance from noise barrier to the track centerline is 3.34m. That means fatigue fail may occur within design life. In addition, for the ballastless track, when the speed is 350km/h and the distance from noise barrier to the track centerline is 4.65m, the fatigue safety factor is greater than 2.5, which means a possibility of a waste of material. |
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