Banca de DEFESA: Letícia Pereira de Morais

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Letícia Pereira de Morais
DATE: 03/11/2022
TIME: 14:00
LOCAL: TEAMS
TITLE:

Investigation of microscopic features of fine grained soils that influence mechanical behavior

KEY WORDS:

microscopic features of soils, kaolinite, Experimental tests, statistical mechanics

PAGES: 124
BIG AREA: Engenharias
AREA: Engenharia Civil
SUMMARY:

Fine grained soils have microscopic features that are directly related to the behavior of theses soils. Among the main aspects can be mentioned the forces between particles and particle arrangement. The knowledge of these features will provide a better understanding of various phenomena and enable more accurate geotechnical analysis. Using kaolinite as material, the present work focused on understanding microscopic aspects of fine-grained soil from experimental tests and the deduction of a formulation to correlate a microscopic feature with compressibility. Two experimental studies were carried out. In the first, the compaction of kaolinite was performed statically and under high loadings (2 to 100 MPa) and different water contents (dry and 10% water content- distilled water and dispersant). Proctor compaction was also performed. With the compacted samples, laser granulometry tests (obtain particle size distribution), scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) were performed. It was possible to observe, with the results, a change in the particle size distribution, with formation of agglomerates of particles, besides making inferences about the main contact forces between kaolinite particles, in which for high loadings the van der Waals interactions prevails. In the second experimental study the collapse of kaolinite was evaluated, using the oedometric test equipment, for different fluids (distilled water and dispersant), different loadings and varying the concentration of the dispersant. SEM and MIP tests were performed with the samples after collapse. From the results it was possible to observe the influence of the fluid and the forces between the kaolinite particles on the arrangement of particles. It was observed that the arrangement of the kaolinite particle is related to a particle orientation distribution which will vary with the fluid and the loading. To correlate the microscopic aspects of the soil with the mechanical behavior it was selected statistical mechanics, which can describe a microscopic feature of materials using a density function. From the entropy maximization principle, a formulation was deduced that incorporated the particle orientation distribution as a microscopic variable. With the formulation it was possible to calculate entropy, using particle orientation distribution data from the literature, and observe a correlation between entropy and compressibility.

BANKING MEMBERS:
Externo à Instituição - BERNARDO CAICEDO HORMAZA - UNIANDES
Externa à Instituição - ANALICE FRANÇA LIMA AMORIM - UFPE
Presidente - 1549489 - MANOEL PORFIRIO CORDAO NETO
Interna - 1519113 - MICHELE DAL TOE CASAGRANDE
Interno - 3132829 - RAFAEL CERQUEIRA SILVA