Estudo do cisalhamento em colunas granulares encamisadas

Abstract

The knowledge about the behavior of granular encased columns (GEC’s) subjected to vertical loads is already well known. However, so far, few studies have been done on the behavior of these structures when subjected to lateral loads, that is, lateral stresses that generate shear. This type of request must be verified in case of embankment stability analysis on soft soils and supported by GEC columns. Therefore, in order to better understand the performance of GEC’s in these situations, direct shear strength tests were performed on columns with different rigidity encasements, making it possible to evaluate the influence that the encasement causes on the columns. In order to assess the influence of the column stiffness module and sand compactness, laboratory tests were carried out, and the test program included the variation of these two parameters. The compactness of the sand was controlled by means of a rain gauge. The tests were performed in direct shear equipment, that is, a reduced model (type 1g). To scale (reduce) the model was based on the dimensions of the columns and unit cell of the TKSA (South Atlantic Steel Company) embankment, Housseinpour (2015). The reduction factor of the actual dimensions (column diameter equal to 80cm) for laboratory ones was 37.67 and this factor was also used to reduce the encasement stiffness module (typically ranging from 1500 to 6000 kN/m). To simulate the geosynthetic liners, low density polyethylene (LDPE) liners were used, with an estimated elastic modulus of 200 MPa. This module represents a J of 20 kN/m for the thickness of 0.1 mm of the LDPE plastic canvas used. The results showed a gain of resistance in the soil as the rigidity of the shirt increased. This gain was more substantial for the granular material in a compact state