Page 246 - 360.revista de Alta Velocidad - Nº 5

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

layers at the level of the interface.

• In case of sliding between two layers: vertical normal stresses and vertical
displacements are the same and a tangential stress is zero in both layers at the
interface level.
(c) At infinite depth:

• Stresses and deformations are nil.

To determine the stresses and the resulting deflection in the layers with this program, the layers
characteristics and the charge of a wheel type have been supposed. So, it has been obtained an
estimate of the variation of the coefficient of ballast between the solution of project and the
different alternatives and the value function of the dynamic load in each structure.
For estimation of stresses in the platform, the following elastic characteristics in each layer
have been considered:

E (MPa) C.Poisson
Soil 50 0,35
Formation layer 100 0,35
Sub‐ballast 150 0,35
Ballast 400 0,35
Soil stabilized 250 0,25
Soil cement 4.000 / 6.000 0,25

The determination of dynamic loads has been a rough, by the method of the SNCF estimate,
based on a static 17.2 t axle load and have been considered two cases, both for speed of 350
km/h, obtaining the following values:

• With sub‐ballast layer and a 50 kN/mm stiffness was obtained a dynamic loading of 12,68
t/wheel.

• With stabilized layers and a 62.5 kN/mm stiffness was obtained a dynamic loading of 14,14
t/wheel.

The output of the program provides graphically the maximum values of the stresses and
deformations of each layer at the level of the different interfaces. It also indicates the place
where these maximums are obtained and determines the value of deflection under the wheel
and the radius of curvature of the deformed.
The following table is a summary of the results where deflection (Dk) and vertical stress on the
top side of the platform (σ ) are showed:
Z
Summary of results:

D 10 mm σ platform
‐2
k Z
traditional sectión 84,11 1,701 ∙ 10
‐2
20 S‐EST + 25 SC (6000 MPa) 55,18 1,364 ∙ 10
‐2
20 S‐EST + 25 SC (4000 MPa) 57,96 1,550 ∙ 10
‐2
25 S‐EST + 20 SC (6000 MPa) 59,77 1,662 ∙ 10
‐2
25 S‐EST + 20 SC (4000 MPa) 62,21 1,838 ∙ 10
‐2

244 360.revista de alta velocidad