Field investigation on the lateral resistance of railway tracks including hot mix asphalt layer

Abstract

One of the most important problems in the ballasted railway tracks is the inappropriate distribution of stress through the ballast over the subgrade layer, which causes damage to the super/substructure layers. Application of hot mix asphalt (HMA) layer in the forms of underlayment or full depth has been proposed in order to decline the stress concentration over the subgrade. Lack of sufficient track lateral resistance, especially in curved routes, is regarded as a concern when using this layer in ballasted railway tracks. Since there is not enough knowledge about the influence of the HMA layer on the lateral resistance of ballasted tracks, the present study was allocated to investigate the mentioned issue by a series of field tests. For this purpose, a test track (including different sections on asphalt layers, as underlayment HMA (with thickness of 100 and 150 mm) and full-depth HMA (with thickness of 100, 150 and 200 mm)) was constructed in Qom-Jamkaran railway line. Afterwards, a series of single tie push tests and track panel displacement tests were performed to measure the lateral resistance of all the test track sections. The results show that the lateral resistance of the common ballasted track is about 75–100% and 55–80% more than that of the ballasted track with underlayment HMA and full-depth HMA, respectively. Hence, on average, the lateral resistance of full-depth HMA track is about 15% more than that of underlayment HMA track.