Page 318 - 360.revista de Alta Velocidad - Nº 5

Sol-Sánchez, Miguel. Moreno-Navarro, Fernando. Rubio-Gámez, Mª Carmen.

of 250 mm. The height of the ballast layer was 300 mm under the sleeper, which is a common
value found in railway tracks, and allows for maintenance tasks (UIC Code 719-1). The ballast
used in this study was composed of ophite, with appropriate size (mainly between 63 mm
and 31.5 mm, EN 933-1) and resistance to fragmentation (lower than 8%, EN 1097-2) for its
application in railway tracks according to EN 13450, as well as the rest of properties were in
consonance with such Standard.
2.2 Test procedure

In order to prove the efficiency of the proposed technique (stone-rubber blowing) to reduce the
railway track maintenance, the testing plan included the analysis of the behaviour of a track
section reproduced in laboratory when different solutions are carried out as maintenance for re-
leveling after ballast settlement. These solutions were: stoneblowing process as conventional
maintenance technique; stoneblowing combined with the application of different USPs used
as rseference elastic element; and the incorporation of diverse quantities of rubber particles
(10%, 25% and 50% over the total volume of the mix of particles blown) used to replace part
of the small stones during stoneblowing process (stone-rubber blowing technique). Figure 2
represents the scheme of the different solutions applied.

Figure 2. Testing plan.

For this study, a series of dynamic tests were carried out in order to reproduce track section
settlement, and then, to simulate maintenance techniques (conventional stoneblowing as
well as the combination of this process with the incorporation of elastic elements) for
analysing the effect of each solution on track section behavior. The dynamic test consisted
of applying 200,000 loading cycles at 4Hz of frequency with a maximum stress over the
ballast surface around 250 kPa. These loading conditions are considered appropriate for
simulating the effects of passing trains (Indraratna et al., 2006; Bach, 2013; Sol-Sánchez,

316 360.revista de alta velocidad