Evaluation of the Technical Alternatives for the Stabilization of the Sublevel Layer in the BRT Sul Corridor Works, Brasília, Federal District, Brazil

Abstract

As a public transport solution, the BRT concept is increasingly common in large cities. The city of Gama/DF, place of implantation of this modal is the result of a Geology characterized by a layer of Clay red latosoils, denominated of porous and collapsible clay. Bibliographical studies indicate that many paving works present exaggerated deformations when the lack of detailed characterization of these profiles, in front of the requests of the traffic. The use of dimensions based on the CBR theory and the verification of the quality of earthworks and pavement layers, do not present satisfactorily the effects of deformability of these structures, since the services of control of compaction affirm a degree of compaction compatible with the services, but when measuring the deformation by the Benkelman beam method, values are set below, to the extent that they are not accepted by the inspection. Important factors such as granulometry, Atebergs limits and the presence of hygroscopic clay minerals accentuate the problem, since these soils present hydration of water in contact with the medium and high capillarity, to the point that it is difficult to maintain optimal moisture during the services and the recompaction becomes impracticable, since the disorganization of macropores makes these soils even smaller from the texture point of view. Due to the degree of difficulty presented in working with these types of soils, and the tight deadline for the implementation of the compaction service stage, five solutions of subgrade reinforcement were proposed and tested in order to direct the most favorable technical and economic solution to the problem to the project schedule. These solutions transit through the uses of structural layers, with Rachão stone; subleito reinforced with microgrel; subleito reinforced with geotextile; compacted subgrade with compacted subgrade with 5% of virgin lime. All the solutions were evaluated in experimental stretches of approximately 100 m of extension, of the work itself, by means of the conventional technological control and with the measurement of the deformation with the use of the benkelman beam.