Aterro estruturado sobre colunas Deep Soil Mixing

Abstract

The demand for infrastructure works in Brazil has been growing, which put pressure on the construction on lands with low support capacity and high compressibility. To enable the construction of this work, a technique, which was recently introduced in Brazil, is the piled reinforced embankment constructed over Deep Soil Mixing columns which consists of the in-situ treatment of the soil, mixed with lime, cement or a composition of these ones with other special binders. On these columns, one or more layers of geosynthetic reinforcement can be installed, in order to optimize the concentration of loads on the columns, which is a phenomenon known as soil arching. This dissertation presents the geotechnical instrumentation and general aspects of the widening project of the Salgado Filho International Airport landing and takeoff runway, located in Porto Alegre (RS). The embankment of the runway was constructed over DSM columns and the settlements measured during the monitoring period were considerably small. In order to evaluate the initial conditions of the project, an estimate of the soil geotechnical parameters is performed from empirical and semiempirical correlations with the results of the piezocone test. In addition, the statistical analysis of the unconfined compressive strength of samples collected from the columns during their execution is performed, in order to verify if they meet the design requirements. Finally, the geotechnical monitoring was carried out from the installation of total pressure cells, the settlement plates and the piezometers on an instrumentation island, in order to allow evaluating the ocurrence of soil arching, as well as monitoring the occurrence of settlements pari passu to the construction of the landfill. That said, it was verified that the structured embankment, in terms of the measured total vertical stress, pore pressure and vertical displacements, behaved as expected, so that there was a reduction of stresses applied in the foundation soil and, therefore, displacements of small magnitude were measured.