| Resumo : |
The thesis topic is the geogrid-reinforced layer based on the Discrete Element Method (DEM). The main objective of the research is to improve the understanding of the interaction between generic geogrids and granular materials, especially those related to micromechanisms. The perspective is that this work can contribute to new studies related to the use of geogrids to optimize the design of such reinforcement. Geogrids as granular layer reinforcement elements have a successful application history throughout the world. In many cases, these structures provide a significantly economical, safe, and environmentally friendly solution. However, the development and optimization of this solution must deal with the complex behavior between the reinforcement and granular material. Thus, the use of numerical methods capable of reproducing the geogrid mechanical behavior (i.e., stretching, bending, shearing, and twisting) and the grain scale soil behavior at the vicinity of the geogrid (i.e., rolling, friction, and abutment effect) can contribute greatly to a better understanding of the soil-geogrid interaction. DEM-based models have this feature with a relatively small number of parameters. Despite this, representative geogrid modeling is still a demand. This thesis comprises a new proposal for discrete geogrid modeling using deformable elements. The numerical construction involved the extensible open-source framework for discrete numerical models YADE and focused on obtaining a realistic flat shape for members of a generic geogrid. Geogrid pullout simulations made it possible to verify the mechanical behavior of the samples and to evaluate the mobilization of forces in the reinforcement. The simulations comprised samples with different amounts of spherical and non-spherical particles. The results obtained were consistent and showed that the particle angularity and the relative size between geogrid openings and particles have a significant influence on the reinforcement strength mobilization. It was also possible to verify that the stresses mobilized in the transverse members of the geogrid during its pullout are significantly lower than those of the longitudinal members, but they are not negligible. Despite the determination of contact parameters is still a difficulty for real cases, the discrete numerical model presented contributes to future studies aiming at the interaction between geogrid and granular materials. |