Influencia de los cambios del contenido de agua en la resistencia al corte de un material granular intermedio compactado

Abstract

This graduated project is focused on the study of the influence of changes in water content on the shear strength of an intermediate, compacted granular material from the Guadalupe Formation, in an outcrop site located south of the city, from Bogotá D. C. Compacted granular materials are partially saturated soils whose mechanical behavior depends both on their structure, characterized by the pore size distribution PSD (Pores Size Distribution), and on their suction component that corresponds to a variable of the fundamental stress state to describe the stress-deformation characteristics of the soil. Through the theory of partially saturated soils developed by (Bishop, 1959), (Fredlund, Rahardjo, & Fredlund, 2012) and its existing relationship between the matric suction and the water content by using the Soil - Water Characteristic Curve (SWCC Soil Water Characteristic Curve), the influence of different net confining conditions on shear strength (that is, c 'and φ') was determined. different stages of drying controlled in the laboratory. The intermediate soil samples were compacted according to the compaction energy of the normal or standard test (INV E-141-13). Method "A" was used to determine the relationship of moisture with the unit weight of the fine fraction for which the material was passed through sieve No. 4 (4.75 mm sieve) seeking to remove the oversizes of the coarse fraction. To explain the mechanical behavior of the material in the direct-shear testing, microstructure observation via Environmental Scanning Electron Microscopy (ESEM) and Energy Dispersive Spectrometry (EDS) were performed, in addition to the index, classification and mechanical properties found in the laboratory. Additionally, partially saturated parameters of the SWCC were established by using filter paper technique. The results obtained explained the importance of understanding the wetting and drying cycles in the shear strenght through the relationship between the matric suction and its moisture content, which is represented by the Soil - Water Characteristic Curve (SWCC), showing that any variation in the water content of the soil mass (increase or decrease in matric suction) produces a change in the internal structure of the soil. For the compacted samples in the “dry side”, lower air entry values are presented compared to the compacted samples in the “wet side” associated with more open structures and low densities until reaching the maximum dry density. It is immediately reflected in the geotechnical parameters of strength, in the same way, the results allowed to understand the importance of environmental conditions in the shear strength behavior of the soil.