Issue 30

A. De Iorio et alii, Frattura ed Integrità Strutturale, 30 (2014) 478-485; DOI: 10.3221/IGF-ESIS.30.58 480 they are partners in a research project whose main aim is a program of full scale tests on a great number of infrastructure archetypes simulating real scenarios of the track service conditions. E XPERIMENTAL PROGRAM rom the analysis of both data required to identify the critical service conditions for the type of tracks described in the Technical Specification (elaborated ad hoc by RFI [17]) and those gathered in literature, useful guidelines have been drawn in order to plan out the type of tests and their number. This information is necessary to define the range of variation of all the parameters on which the aforementioned critical situations depend. The parameters are:  Type of sleeper (A i );  Degree of ballast compaction (B i );  Shoulder dimension (C i );  Distance of the end of the sleeper from the ballast retaining wall (D i );  Height of the ballast in correspondence of the ends of the sleeper (E i );  Type of the anchor of the sleepers (F i );  Effect of the superelevation-cant (G i );  Lowered ballast profile between two sleepers for a width of 2 m (1 m for each side in respect to the track axis) (H i );  Height of ballast under the sleeper (I i );  Applied vertical load (L i );  Type of ballast material (M i ). The combinations of all these parameters would obviously lead to define an onerous number of scenarios to be reproduced in the experimentation if the subscript “i” assumes at least 3÷4 different values, therefore it is compelled to make a trade-off choice in order to realize a narrow number of tests, but sufficiently significant to make, on the basis of the results obtained from them, both numerical and mathematical models able to effectively simulate all the scenarios corresponding to the parameter values belonging to the predetermined fields of variation. On the basis of significance and representativeness considerations of the chosen track service conditions, as well as of economies of scale, 26 scenarios have been selected; they are summarized in Tab. 1. M1, C2, H1, E1, A1, I1, B1, L1 M1, C2, H1, E1, A2, I1, B2, L2 M1, C2, H1, E1, A2, I3, B2, L1 M1, C2, H1, E1, A1, I3, G2, B1, L1 M1, C2, H1, E1, A1, I1, B1, L2 M1, C2, H1, E1, A1, I1, B2, L1 M1, C2, H1, E1, A2, I3, B2, L2 M1, C2, H1, E1, A1, I3, G2, B2, L1 M1, C2, H1, E1, A2, I1, B1, L2 M1, C2, H1, E1, A1, I1, B2, L2 M1, C2, H1, E1, A2, I3, B1, L1 M1, C2, H1, E1, A1, I3, G2, B2, L2 M1, C2, H1, E1, A2, I1, B1, L1 M1, C2, H1, E1, A1, I3, D3, B2, L1 M1, C2, H1, E1, A2, I3, B1, L2 M1, C2, H1, E1, A1, I3, F2, B2, L2 M1, C2, H1, E1, A2, I1, D3, B2, L2 M1, C2, H1, E1, A1, I3, D3, B2, L2 M1, C2, H1, E1, A1, I3, B1, L1 M1, C2, H1, E1, A1, I3, F2, B2, L1 M1, C2, H1, E1, A2, I1, D3, B2, L1 M1, C2, H1, E1, A1, I3, B2, L1 M1, C2, H1, E1, A1, I3, B1, L2 M1, C2, H1, E1, A1, I3, F1, B2, L1 M1, C2, H1, E1, A2, I1, B2, L1 M1, C2, H1, E1, A1, I3, B2, L2 M1, C2, H1, E1, A1, I3, G2, B1, L2 M1, C2, H1, E1, A1, I3, F1, B2, L2 A1 = RFI 230 pre-stressed concrete sleepers; A2 = RFI 240 pre-stressed concrete sleepers. B1 = de-consolidated ballast bed; B2 = DTS consolidated ballast bed. C2 = 60 cm ballast shoulder. D3 = ballast retaining wall 60 cm apart from the sleeper end. E1 = regular ballast shoulder top profile. F1 = sleeper anchors at every 2 nd sleeper; F2 = sleeper anchors at every sleeper. G2 = canted track. H1 = non lowered ballast profile. I1 = 30 cm ballast thickness; I3 = 60 cm ballast thickness. L1 = unloaded track; L2 = loaded track. M1 = regular ballast material. Table 1 : Scenarios included in the testing plan: characterizing parameters. In order to establish a future correlation between test results and geometrical, mechanical and behavioural characteristics of all components and related materials used during testing, it has been decided to perform also a series of F