Equipamento triaxial cíclico de grande escala para análise mecânica de lastro ferroviário

The ballast layer usually is responsible for giving support to the railway superstructure and is loaded and unloaded repeatedly due to the passage of trains. In this context, the comprehension of the stress-strain characteristics of this noncohesive material used in that layer is important for optimizing maintenance operations, thus ensuring a safe and efficient transport. The material used in ballast layer is usually composed of highly coarse-graded gradation, hence large-scale laboratory tests are more difficult to conduct. The purpose of this paper is to evaluate the applicability of a new Brazilian large-scale triaxial apparatus (400 mm x 800 mm) that allows testing large-size particles such as in the field, without the need of scaling aggregates and ensuring more representativeness. Thus, it is possible to simulate loading that occurs due to the passage of trains, in order to observe the mechanical behavior of ballast in terms of resilient and permanent deformations. A cyclic triaxial test carried out with that apparatus showed the availability of preparing large-size samples and obtaining results of resilient modulus and permanent deformation compatible with what was being expected.