Page 240 - 360.revista de Alta Velocidad - Nº 5

López-Bachiller Fernández, Miguel. Sampedro Rodríguez, Ángel. Díaz Minguela, Jesús.

1. Object of this communication

Since ancient times, all kind of soils have been improving in order to obtain a better
use of them, getting more support and better resistance to the passage of time and the
weather effects. These soils were modified with small additions of different materials,
improving or stabilizing such soils.
Clay stabilized with lime has been used for the construction of the Shersi's pyramids in
Tibet more than 5,000 years ago. Later on, already in the modern era, cement Portland
was used to give resistance to the soils in cobble roads. In addition, it was used as well
to stabilize a network of rapidly building airfields during World War II, giving way to what
today we know as the modern roads.
Currently, soils stabilization is a technique of application widespread in many public and
private works as factories, airports, ports, and all kinds of roads, from rural roads to mo‐
dern motorways.

The purpose of this communication is to show the use of the technique in the construction
of new railway works, achievements and targets set for the near future.

2. The technique

The load‐carrying capacity of the platform and the tensions that comes to it through
dynamic loads of rail traffic is critical for determinate thickness of layers in any
superstructure seat in earthwork projects. One of the goals of a correct dimensioning
about railway's superstructure is to obtain vertical tension on the top side of the platform
results clearly lower than its bearing capacity.
To improve the ability to increase the support capacity of the embankments in areas
where clays or other lands with low resistance are, lime or cement can be used in order
to improve the results obtained with these soils and to minimize the transportation of
large masses of earth.

In addition to other objectives, minimize the construction costs, both economic and
environmental, and the tasks of maintenance are the targets, reducing the technical and
mechanical damages that maintenance work involves.
The rail traffic planned for the future and stresses that it will generate must be taken in
account as in any type of project. If it is expected that this traffic to overcome to the
admissible, it must be intervened to reduce tensions, by means of the modification of the
railway seat structure, the increase of the platform capacity bearing or both actions at
the same time.

There are still various uncertainties we can found regarding to:

• dynamic actions in the case of the high speed railway,
• the fatigue of materials behavior that are more requested

• the lateral resistance of the track and
• the maintenance of the mechanical properties obtained in the construction of the
structure.

Consequently, this is one of the aspects that most should worry. International research

238 360.revista de alta velocidad