Dynamic Responses of Asphalt Concrete Waterproofing Layer in Ballastless Track

Jie Zhou,Degou Cai,Gang Xu,Qinghong Fu,Xianhua Chen

doi:10.3390/app9030375

Jie Zhou, Degou Cai + Show 3 more

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https://doi.org/10.3390/app9030375

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Abstract

The application of asphalt concrete waterproofing layer (ACWL) for the subgrade has been a trend in Chinese high-speed railway. The purpose of this research is to discuss the dynamic characteristics of full cross-section ACWL in the ballastless track structure under the train loads. The laboratory tests were conducted to evaluate the performance of the asphalt mixtures for the ACWL and a test section of ACWL was constructed on the high-speed railway in north China. The linear viscoelastic behavior of the asphalt concrete obtained from the test section was characterized by the generalized Maxwell model according to the results of dynamic modulus test. Then a 3D finite element model for the interaction system of vehicle and ballastless track structure was presented and validated by field measured data. The results indicated that the tensile strain at the bottom of the ACWL was at a relatively low level and the vertical dynamic responses of each structural layer are obviously reduced due to the application of ACWL. Therefore, the full cross-section ACWL helps to reduce the vibration of the track structure and maintain the long-term stability of the subgrade.

Highlights

The waterproofing layer, as an important part in railway substructure, is usually set on the surface of subgrade to prevent the infiltration of water from the surface into the body of the subgrade.The infiltration of water will lead to a decrease of soil strength and cause various engineering issues under the dynamic load of the train, such as mud pumping and subgrade settlement [1].The application of the waterproofing layer for the seasonally frozen regions is essential for controlling the frost heave of subgrade [2]
The test results of the laboratory tests fully meet the proposed technical requirements, which ensure that asphalt concrete waterproofing layer (ACWL) can satisfy the functional requirements during the service life
A test section of ACWL for the ballastless railway was constructed in north China and the field test results prove that the proposed requirements are reasonable and reliable

Summary

Introduction

The waterproofing layer, as an important part in railway substructure, is usually set on the surface of subgrade to prevent the infiltration of water from the surface into the body of the subgrade.The infiltration of water will lead to a decrease of soil strength and cause various engineering issues under the dynamic load of the train, such as mud pumping and subgrade settlement [1].The application of the waterproofing layer for the seasonally frozen regions is essential for controlling the frost heave of subgrade [2]. The traditional materials used for the waterproofing layer on the high-speed railway in China is cement concrete. The related field investigations show that the early constructed concrete waterproofing layer in north China is prone to cracking due to the brittleness of concrete materials and because maintenance is relatively difficult [3]. In this case, the asphalt concrete, as a viscoelastic material with both mechanical strength and flexibility, has been applied to the waterproofing layer for the railway subgrade. The asphalt concrete was applied as the track bed for the

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