PLATE DIMENSION EFFECT ON PLATE LOAD TEST RESULTS IN SAND
shallow foundations, dimension effect, relative density, sand.
Plate load tests represent an important tool on foundation design because it allows to define allowable stresses and settlements. However, when carried out on sand, the extrapolation of the results from the model (plate) to the prototype (foundation) becomes more complex, as compared to tests on clay. This work aims at evaluating the plate dimension effect on the result of plate load tests in sand. The study included analyses field in the test results and numerical simulation. The plate load tests in the field were carried out in sand deposits, with relative densities of 45% and 70%. These tests were executed with quick maintained load using plates with 0.30, 0.50, 0.80 m in diameter. In an attempt to better evaluate the effect of the dimension of the plate, the numerical simulations were carried out with plate dimensions ranging from 0.15 to 3.0 m. The main goal of this phase of the research was to assess the effect of the plate dimension on the allowable stress and the corresponding settlement of the plate. The numerical simulation was performed by using the finite element software Plaxis 2D and the behavior of the soil was represented by the hyperbolic model Hardening Soil. Since a clear failure pattern was not possible to be identified with the stress-settlement curves, different “conventional” failure criteria were used to find the corresponding allowable stress. Distinct allowable stress values were obtained with the different methods. The plate dimension effect on the allowable stress was found to be dependent on the assumed failure criterion. Differently from what the theoretical methods predict, the allowable stress followed a non-linear increase with plate dimension. Lastly, the influence of the soil relative density on the plate soil results was assessed for different plate sizes. It has been found that the relative density plays a low influence on stresses and settlement variation with the plate diameter. tensões e recalques com o aumento da dimensão.