Comparative Analysis of Vibration Characteristics of Underground Support Blocks under Dynamic and Cyclic Loading

Abstract

The object of research is various designs of support blocks with intermediate fasteners for underground areas of both domestic and foreign production. An integrated approach to testing block track structures is proposed and implemented: modeling of cyclic loading typical for the entire track structure, as well as shock loading typical for intermediate butt rail fastenings. The test frequency is set to 10 Hz under cyclic loading. A method is presented for improving the testing equipment in the framework of modeling the transfer of loads from the wheel to the rail in the plane of contact between the rolling surfaces of the wheel and the rail. The main results of the tests are presented. Under dynamic loading, the maximum forces in the rail arise in a structure with a conventional pad (of the order of 50–55 kN), a more complex spectrum of force variation with a maximum amplitude of about 20–25 kN and a span of 30–40 kN is characteristic of the Metro wooden block. The lowest values of vibration accelerations in the implementation of this approach are shown by the LVT block. Structures with a vibration isolating pad have the highest vibration acceleration values in the frequency range from 10 to 31.5 (40) Hz. In the zone of higher frequencies, the investigated structures have comparable values of vibration accelerations. The analysis of vibration characteristics is carried out on the basis of the recorded values of vibration accelerations in characteristic measuring points. The values of vibration accelerations and their relative comparison are given depending on the installation position of the measuring channels and on the type of construction. It is noted that in the 10 Hz zone the values of vibration accelerations are minimal when using a vibration isolating pad with a hardness of 65 Shore A. Comparative results for frequencies of 31,5 and 63 Hz are presented. It is recommended for the design options that showed the best results to conduct operational tests in underground conditions.

Keywords

• support blocks
• railway track
• underground
• elastic elements
• rolling stock
• axial load
• frequency
• test equipment
• vibration acceleration
• vertical forces