Page 266 - 360.revista de Alta Velocidad - Nº 5

Álvarez, Fernando. Balmaseda, Lucía. Gallego, Inmaculada. Rivas , Ana. Sánchez-Cambronero, San

1. Introduction

In recent years, rail transport has experienced great expansion throughout the world,
becoming an efficient and competitive transport system for countries with thousands
of kilometres of track. In the coming decades, it is envisaged that new and ambitious
railway projects will be developed, whose technical difficulties in the interaction with the
environment by which it intends to circulate the route and the reach of greater speeds on
this one, make it a real challenge for civil engineering; such as the expansion of the High-
Speed network in China (Abu Sayeed and Shahin, 2016) and the expected development of
the High-Speed line in the United States (Fort and Fort, 2016).

With regard to High-Speed networks, the demographic and economic growth of many
countries, which have such a rail network with optimum operating conditions and study
experience, have led to higher speeds in order to comply the demand and / or economic
objectives required of this transportation system. The increase of the speed could generate
an increase in the values of the loads that are transmitted to the railway platform, being
the speed proportional to the value of this one. This is related to the effect of the weight of
the non-suspended masses of the train, since, if this weight does not change but increases
the speed value, the dynamic effects that occur in the vehicle-track interaction, generates
a dynamic overload that increases the values of the loads to be supported by the track. If
we now refer to rail freight transport, future commercial expansion of several countries
may lead to increased freight and / or transport capacity by trains, either by increasing the
number of cars or the axle load being transmitted to the railway platform (Li, et.al., 2016).
These increases in the magnitudes of the loads show that, if it is desired that this transport
system correctly fulfils its function, the train must circulate by a means that guarantees
safety and stability to the infrastructure and comfort for the passengers and loads to be
transported.
On the other hand, awareness of the economic and landscape impact generated by the
design and construction of a High-Speed lines has led to an awareness of the importance of
valuing and treating the local materials of the trace, avoiding the massive waste of these
through their disposal can consider the possibility of subjecting them to a treatment that
improves their geomechanical behaviour (Gomes Correia, et.al., 2016), and make it fit to
be usable in the construction of the railway platform.

So far, the sizing of the railway platforms has been carried out from the point of view
of the experience obtained in the realization of projects, being in the case of the High-
Speed, a very conservative sizing for the seat layers that form the railway platform. In the
current context of economic crisis, it is necessary, in the field of exploitation and design, to
introduce certain design criteria so that the cross-section of the railway is defined according
to criteria of efficiency and rationalization of the same.
These three aspects; increase of the loads that request the railway platform, geomechanical
characterization of recycled materials that form it, and introduction of new criteria that
realize a rational and efficient design of the platform; are the key reasons for carrying out
a study that has, as a final objective, the design of the railway cross-section in accordance
with criteria of technical efficiency, being stable and functional in the face of high load
conditions and economic efficiency, avoiding an oversizing of the same .

The purpose of this paper is to describe the elaboration of design recommendations, for
which it has previously been necessary to make a numerical model from the refined other
existing model, and can also serve as a future phase in the performance of a dynamic
analysis.
Finally, the structure of the following article is described, being organized as follows:

264 360.revista de alta velocidad