Abstract:
In recent years, a hot mix asphalt layer, known as an underlayment, has been replacing
granular sub-ballast in high-speed and heavy haul tracks, aiming to overcome the
limitations of traditional ballasted railways. However, there is a lack of literature
regarding the impact of this layer on the slope stability of railway embankments. Ensuring
the safety of trains and track availability requires a thorough understanding of
embankment slope stability. Hence, this study examined the influence of the underlayment.
layer on slope stability in ballasted high-speed railway embankments. Using Slope/W
software, twelve embankment models with 2H:1V and 1.5H:1V slopes were analyzed. Half
the number of the models were traditional ballasted, while the others incorporated the
underlayment layer. Different heights (3, 6, and 8m) were simulated to evaluate the effect
on slope stability for both slope levels and track cross-sections. The analysis focused on
gravitational force and neglected the increase in pore water pressure. Safety factors for
slope slipping surface were used to quantify stability. The findings revealed that the
underlayment layer enhances slope stability by 8% to 31% in high-speed railway
embankments. However, the degree of improvement decreases with increasing
embankment height, and steeper slopes benefit more from the underlayment layer
compared to gentler slopes. While these results are promising, further research is needed
to investigate the impact of varying pore water pressure on asphaltic tracks.
