Banca de DEFESA: Gabriel de Sousa Meira

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Gabriel de Sousa Meira
DATE: 15/07/2022
TIME: 14:30
LOCAL: Plataforma Teams
TITLE:

Use of Seismic Refraction and MASW Methods for Investigation and Characterization of Slopes

KEY WORDS:

Applied geophysics; Seismic methods; Geotechnical investigations; Surface seismic; Geophysical monitoring; Mass movements; Alert systems

PAGES: 152
BIG AREA: Engenharias
AREA: Engenharia Civil
SUBÁREA: Geotécnica
SPECIALTY: Fundações e Escavações
SUMMARY:

Geophysical methods are increasingly being applied in geotechnics, and be very useful for obtaining more comprehensive information on the subsoil and for monitoring the behavior of masses. Despite this, there is still much demand for scientific studies aimed at correlating the data obtained by seismic methods with those from geotechnical investigations, involving field and laboratory tests and monitoring, particularly as a complementary tool to risk management applied to mass movements and related processes. In this context, this work aims to evaluate the use of seismic refraction and MASW methods in geotechnical characterization and in the feasibility of detecting mass movement. For that, geotechnical investigations and geophysical surveys were carried out in a vertical excavation, with a depth of the order of 9m, before and after the end of the work. For both methods, the same seismic arrangement was adopted, which is composed of two Geode seismographs and 48 vertical geophones, with a resonance frequency of 14 Hz, arranged in a longitudinal line close and parallel to the excavation crest. In addition, soundings and laboratory tests were carried out (characterization, double oedometric, direct shear, and triaxial compression) in samples of the two soil horizons intercepted by the excavation. Comparative analyzes contributed to the verification of the relationships between the results of geophysics and the properties and behavior of soils. A good correlation was observed between the seismic MASW and refraction methods with the SPT type sounding, in the identification of the layers. The increase in VS and VP wave speeds with depth allowed us to evaluate the interfaces between the soil layers. It also verified the potential of seismic methods to identify layers of porous soils with collapsible behavior, which constitute important problems for geotechnical works. For To monitors movements, the feasibility was verified, through changes in soil stiffness resulting from the excavation and containment carried out. As the changes in the stress state were significant, the resonance frequency was able to identify the changes promoted by the excavation. However, in earthworks or natural massifs, excavated or not, to detect deformations, usually small, which would lead to a precarious condition of balance, low frequency, and automatic reading seismic sensors would be needed.

BANKING MEMBERS:
Presidente - 3132829 - RAFAEL CERQUEIRA SILVA
Interno - 404827 - ANDRE PACHECO DE ASSIS
Externo à Instituição - MARCELO PERES ROCHA - UnB