<p>Under dynamic force from the operation of highspeed trains, the sudden change in track stiffness at the railway bridge approach imposes negative impacts on the track component and ride comfort of track users. This study proposes a concept to alleviate the abrupt bump at this transition by introducing a new backfill material. This research aims to develop a sustainable backfill foundation for the railway approach zone having an easy application, high stress-bearing capacity, and thereby, gradually equalizing the track stiffness variation. To cope with objectives, local clay soil, cement, and air foam technique are utilized to fabricate the flowable material. The engineering properties of this mixture are evaluated by conducting the flowability, setting time, unconfined compressive strength, and frost-damage test. Then, the best mix design is employed in the numerical simulation analysis to verify its effectiveness under high-speed train loads at the bridge approach zone. The test results indicate that both foam and cement have a strong relationship with the strength gain of flowable backfill material. The material designed for the bridge approach is suggested to have a cement ratio of higher than 200 kg/m<sup>3</sup> and air foam lower than 20% by mixture volume to adapt the practical application. From the laboratory and simulation analysis findings, flowable clay soil is recommended as an ideal replacement of conventional cement-treated base of the railway bridge approach to improve the service life of the whole track system and promote sustainability purposes.</p>

Laboratory and Numerical Investigations on the Performance of Flowable Soil as a Sustainable Backfill for Railway Bridge Transition

Paper Proceedings: https://asmedigitalcollection.asme.org/JRC/JRC2021/volume/84775

2021 Joint Rail Conference (JRC2021)

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