Abstract Mass movements are frequent natural phenomena and especially dangerous due to increased population and irregular settlements in mountainous areas. Carrying out studies using methods that allow the numerical evaluation of their behavior is essential to mitigate and prevent these events' possible impacts. The traditional Limit Equilibrium and Finite Element methods fail to reproduce the problem from the beginning of the movement until the end of its development, so it is necessary to use new formulations. In this work the Material Point Method was selected to evaluate these movements in the stages of failure mode formation and development of landslide through an analysis of the soil shear strength and deformability parameters of a slope using the elastoplastic model with Mohr-Coulomb failure criterion. Maintaining a geometry and assuming soil mass behaves like a fluid, a single strength parameter and a single deformability parameter are analyzed to understand their influence before and after the failure.

RESUMEN Los suelos estructurados, tales como las lateritas residuales o las cenizas volcánicas, abundan en las regiones tropicales. El comportamiento hidromecánico de estos suelos está claramente relacionado con su estructura. Las nuevas técnicas basadas en estudios microestructurales constituyen una poderosa herramienta para investigar estos suelos. Este trabajo presenta una investigación experimental que documenta las relaciones entre la microestructura y el comportamiento mecánico de estos suelos. Este estudio se centra en el comportamiento microestructural de la arcilla de Brasília, un suelo tropical estructurado y altamente poroso (n> 50%) con una distribución de tamaño de poros (PSD) bimodal. Fueron utilizados los análisis de PSD para investigación de la microestrutura del suelo en diferentes estados y con diferentes índices de vacíos. Se utilizó la técnica de porosimetría por intrusión de mercurio (MIP) para explorar la PSD de muestras en diferentes condiciones, es decir, natural, compactado, lodo o estados consolidados. Se realizó la modelación de las curvas PSD utilizando la curva bimodal de Van Genuchten, que permite el enlace de curvas PSD a la curva de retención de agua. Observamos que la aplicación de carga sobre las muestras de suelo y la compactación de las mimas no afectaron los microporos y se concluyó que los cambios que ocurrieron en este suelo fueron completamente dentro de los macroporos.

ABSTRACT Structured soils, such as residual laterites or volcanic ashes, abound in tropical regions. The hydromechanical behavior of these soils is clearly related to their structure. New techniques based on microstructural studies constitute a powerful tool for investigating these soils. This work presents an experimental investigation that documents the relationships between the microstructure and mechanical behavior of these soils. This study focuses on the microstructural behavior of Brasília clay, a structured, highly porous tropical soil (n>50%) with a bimodal pore size distribution (PSD). The microstructure was investigated using PSD analyses of different structural states and void ratios. The mercury intrusion porosimetry (MIP) technique was used to explore the PSD of samples under various conditions, i.e., natural, compacted, slurry or consolidated states. Modeling of the PSD curves was performed using the bimodal van Genuchten curve, which permits the linking of PSD curves to the water retention curve. We observed that loading and compacting did not affect the micropores of this soil and concluded that the changes occurred entirely within the macropores.