Sobre a construção da curva carga-recalque equivalente de prova de carga convencional a partir de prova por método bidirecional

Abstract

This work addresses the behavior of piles in bidirectional load tests, compared with conventional tests, making use of the Finite Element Method. The SigmaW software is used, in an axisymmetric solution, with linear elastic, hyperbolic and elasto-plastic models of soil behavior. The study seeks to evaluate the differences in shaft friction mobilization in the two loading modes. Regions with displacements in opposite directions (ascending and descending) and the differences in stress distribution in the soil are observed. Firstly, a parametric study (hypothetical cases) evaluates different length/diameter ratios and ground profiles. Initially, a simple, elastic-plastic approach is used, with the prediction of settlement for the service load by the Randolph method and the failure load by a theoretical method of calculation of load capacity. Then, the connection between the two states (a point on the load-settlement curve in service and a vertical asymptote at the failure load) is made with the Van der Veen curve. This work also presents a case study of two nearby auger piles, one subjected to a bidirectional load test and the other to a conventional test. The Mohr-Coulomb elasto-plastic soil model was used in numerical modeling, with soil resistance and deformability parameters estimated from a SPT and a sensitivity study. The results of the analyzes allows some suggestions for extrapolating the results of bidirectional tests to the behavior of the piles when loaded from the top – actual working condition –.