Student): BARBARA VIAPIANA DE CARVALHO
Candidate for the Degree: PhD in Civil Engineering from the Pontifical Catholic University of Rio de Janeiro (PUC-Rio)
Title: Investigation of the Influence of Plasticity on the Effects of Time and Rate of Deformation on the Behavior of Saturated Clays
Data: 19 September 2024
Working Hours: 14:00
Virtual Room:
https://puc-rio.zoom.us/j/97139378635?pwd=THM7z5QOhahqY5AOvm3iO94UHtE9AG.1
Meeting ID: 971 3937 8635
Password: 964051
Summary: In this research, long-term triaxial CIU and oedometric consolidation tests were performed on clay samples, aiming to study the influence of plasticity on the effects of time and deformation rate. Understanding that plasticity is associated with the viscous property of the adsorbed water layer that surrounds the clay grains, this research also seeks to understand the behavior of these soils from the perspective of the stress-deformation-strength-time model of clayey soils that has been developed by the Soil Rheology Group of COPPE/UFRJ, which admits the existence of a viscous portion in both the effective normal stress and the shear strength. Clays manufactured from mixtures of kaolin and bentonite (with contents of 10, 20 and 30% of bentonite) were studied, as well as reconstituted clays produced from samples extracted from the Sarapuí II experimental field, located in Rio de Janeiro. The results of the oedometric tests showed that plasticity influences the compressibility of the clays, with an increase in the compression index and a decrease in the consolidation coefficient observed with increasing plasticity. Monitoring of the secondary consolidation of the clays suggests that the end line of the secondary is further away from the “end” line of the primary the more plastic the soil is. The results of the triaxial tests indicated that plasticity directly influences the viscous portion of the resistance, promoting both an increase in the viscosity coefficient and an increase in the velocity effect. The results also indicated that the friction portion of the resistance establishes a unique relationship with the void index and, therefore, is independent of the deformation velocity.