Computational homogenization applied to the study of conglomerate-type soils of the Ecuadorian Austro

Abstract

The soil type in Cuenca, Southern Ecuador, is called conglomerado (conglomerate, a heterogeneous soil composed of a mixture ranging from decimetric stones to clay). Experimental values of the characteristics of this material are hardly available, mainly because the size of the specimens is difficult manageable in a standard laboratory. To deal with this problem, the authors used a methodology based on computational homogenization. The main ingredient is a computational model of the material that allows performing virtual experiments over a representative volume. In order to build this model, the elastic properties of the components are experimentally defined. In the study two elements were considered: boulders, stones with diameters over ¾ of an inch, and matrix, the rest of the material. The matrix properties were found by performing triaxial tests on samples with the same specific weight and in situ moisture content. The properties of the other component, boulders, were derived from literature. The representative volume was determined on the basis of the characteristic length and the distribution of the components over the volume. The first issue was tackled by using a computational asymptotic analysis. The second issue was dealt with by using photographs of natural slopes of the material. A sensitivity analysis to determine the most relevant factors (size, shape, distribution, components properties) was performed. Then, by using the properties of each component and allowing the relevant factors to vary, a range of values for the Young modulus (E) and the Poisson ratio (υ) of the composite were obtained.