Abstract
The equipment scheduling and propagation characteristics of vibration wave from vibratory roller ⟶ filling material nonlinear systems with multistability are the core problems of subgrade intelligent construction technology, and the logistics scheduling of the equipment is directly related to the construction efficiency. Aiming at the shortages, one typical subgrade located at the Gu’an station of Beijing-Xiong’an city railway is selected to research and finish the field tests; some findings are shown as follows: first, some valuable suggestions about the logistics scheduling of intelligent equipment are proposed, which can break the barriers between the organizations and improve construction efficiency; second, when the vibration wave propagates from the vibratory roller ⟶ surface of filling material ⟶ different buried depths of filling material, the peak acceleration of vibration wave gradually decreases and is hyperbolic distribution approximately. At the same time, the sensitive of attenuation is shown as follows: Z<X ≈ Y, and the critical depth of vibration energy propagation is about 1.0 m. At the same time, the peak acceleration of vibration wave at the interface of different filling material layers exists in steps and is “side clock” distribution approximately with the increase in buried depth. Third, in the propagation process, with the increase in buried depth, the amplitude of fundamental, primary, secondary, until fifth harmonics decreases exponentially (R2>0.9), and the concrete functional relationship among different amplitudes of harmonics can be summarized as y = Ae−BX; fourth, the vibration energy is mainly concentrated near 10–30 Hz in the vibratory roller, but when the vibration wave propagates from vibratory roller⟶filling material, the vibration energy gradually decreases with the increase in depth, and the marginal spectrum gradually changes from one peak to two peaks, that is, 30–50 Hz and 50–100 Hz; fifth, the vibration energy in the vibrational wheel is distributed averagely in the compaction process, and the effective compaction time is two seconds, which will be helpful for revealing the propagation characteristics of vibration wave, optimizing the compaction quality control models and providing some support for the development of intelligent compaction theory of railway subgrade.
Highlights
China has built the world’s largest high-speed rail network whose operating mileage reaches 22,000 kilometers and it will be expected to reach 38,000 kilometers in 2030, which will form a high-speed railway network with “eight-vertical and eight-horizontal” as the main channel. e ratio of length of subgrade to total mileage of high-speed railway is more than 30%, which has been an important part of railway infrastructure and the basis for carrying the track structure and trains
The vibration wave is a complex nonlinear signal; amplitude and frequency of the vibration gradually change with time, which will affect the reasonability of analysis results if it is analyzed from the time domain or the frequency domain alone. erefore, the propagation characteristics of vibration wave should be studied from time domain, frequency domain, and joint time-frequency domain by some new signal analysis technology
Some valuable test data are used to study the propagation characteristics among soil layers in different depths during the vibration compaction process from time domain, frequency domain, and joint time-frequency domain by Hilbert–Huang transform, which will be helpful for optimizing the compaction quality control models and providing some support for the development of intelligent compaction theory of railway subgrade
Summary
China has built the world’s largest high-speed rail network whose operating mileage reaches 22,000 kilometers and it will be expected to reach 38,000 kilometers in 2030, which will form a high-speed railway network with “eight-vertical and eight-horizontal” as the main channel. e ratio of length of subgrade to total mileage of high-speed railway is more than 30%, which has been an important part of railway infrastructure and the basis for carrying the track structure and trains. Significant engineering achievements have been made in terms of intelligent compaction, but its research on the basic theory has just started; the propagation characteristics of Complexity vibration wave in the compaction process are still not clear enough, and a lot of research studies mainly focus on numerical simulation, theoretical analysis, and laboratory test [4,5,6,7,8,9,10,11] [12]. Erefore, the propagation characteristics of vibration wave should be studied from time domain, frequency domain, and joint time-frequency domain by some new signal analysis technology. Some valuable test data are used to study the propagation characteristics among soil layers in different depths during the vibration compaction process from time domain, frequency domain, and joint time-frequency domain by Hilbert–Huang transform, which will be helpful for optimizing the compaction quality control models and providing some support for the development of intelligent compaction theory of railway subgrade
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