Track substructure assessment using non-destructive load tests. A Portuguese case study

AbstractNowadays, there is an increased interest in developing performance based specifications for quality control during the construction, that can provide more realistic information about the life cycle behaviour of the track.In this research, Falling Weight Deflectometer (FWD) tests were undertaken during the construction of a 29km new railway line, at the top of the substructure and in different months. Based on FWD deflections, structural models of the track were established through back-calculation, and the variation of the moduli for different testing campaigns was evaluated. The main results obtained are presented and analysed in this paper

Ground penetrating radar investigations in the noble hall of São Carlos theater in Lisbon, Portugal

This paper describes a study conducted by the National Laboratory for Civil Engineering of Portugal (LNEC), in cooperation with the Defense University Center at the Spanish Naval Academy and “La Sapienza,” University of Rome, to assess the health and safety conditions of the Noble Hall floor in the São Carlos National Theater (Lisbon, Portugal). In a multidisciplinary approach, extensive fieldwork was carried out. The survey included the location and characterization of beams in the various areas of the floor by using two ground penetrating radar (GPR) systems equipped with two different ground- or air-coupled antennas, local inspection openings to visually assess the geometry, timber species and conservation state of structural members, and an assessment of the conservation state of the timber beam ends using drilling equipment. All the tests performed and the results obtained are presented. The potential of using non-destructive tests for the inspection of timber cultural heritage structures, particularly GPR, is discussed, and some practical recommendations are made

Bituminous mixtures application in railway sub-ballst layer

The increasing of loads and traffic speed of the railways requires a better infrastructure, in order to enable the operation in optimal condition and less traffic interruptions due to maintenance actions. At the same time, the natural resources for the material generally used in the sub-ballast layer, namely the granite are limited, taking into account that the requirements in terms of stiffness and wearing resistance are very high. The bituminous mixtures can represent a good alternative to this traditional material. They enable the decreasing of sub-ballast thickness, better impermeability, better behaviour under the lorry traffic during construction and an improvement of the infrastructure stiffness and its continuity along the railway that results in less maintenance works. In this study two different structures are compared, one with granular material and the other one with bituminous material as sub-ballast layers. Falling Wheight Deflectometer (FWD) tests were performed in order to establish the structural model. The back-calculation was made using both linear elastic and finite difference method. The results obtained so far are presented in this paper, together with some proposals for future developments