Banca de DEFESA: LARISSA FERREIRA DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LARISSA FERREIRA DA SILVA
DATE: 30/06/2022
TIME: 09:00
LOCAL: Programa de Pós-Graduação em Engenharia Civil on line
TITLE:

Collapsible Soils in the Brazilian Semi-Arid: a panoramic view

KEY WORDS:

Semiarid; Collapsible Soil; BANDASE, Occurrences; Identification; Methods; Tests; Hydrogeomechanical behavior.

PAGES: 166
BIG AREA: Engenharias
AREA: Engenharia Civil
SUMMARY:

In semi-arid regions, where the evapotranspiration rate is higher than the infiltration rate, it is possible to observe the occurrence of collapsible soils and there are records of serious damages in constructions based on these soils. From the consultation of the Special Soils Database – BANDASE, initiated by Ferreira (1990), geotechnical information on 112 occurrences of collapsible soils, found both in large-scale engineering works and in small-scale buildings, distributed between 30 cities in 7 states in the semi-arid region of Brazil. Physical, chemical, mineralogical and microstructural characterization data were collected and analyzed, as well as single and double edometric tests, direct shear tests performed before, during and after the flood, and field tests (SPT, SPT-T, expandocollapsometer, load test on plate, Ménard pressure gauge, light dynamic penetrometer – DPL, static penetrometer – PE, light impact deflectometer – LWD). Interpretive maps of susceptibility of occurrence of collapsible soils, based on Pedology, Geology and Climate were elaborated, as well as artificial neural networks (ANN) and numerical models capable of simulating the collapsible behavior, and soil improvement techniques were also employed. The highest number of occurrences of collapsible soils in the Brazilian semiarid region were registered in the states of Pernambuco (43,24%) and Bahia (30,63%). There is a predominance (88,57%) of sandy textured soils in relation to clayey ones (11,43%). The larger particles are essentially constituted by quartz grains and the clay fraction has as main components the minerals kaolinite and mica. Acid soils (90,91%) predominate in relation to alkaline soils (9,09%). The average value of the real density of the grains (2,66) combined with the low average specific weight of the soil (15,98 KN/m3), indicates the occurrence of a macroporous structure, whose average porosity is 45,40%. This characteristic, together with the low humidity (average humidity of 5,05%), results in an average saturation degree of 17,78%. The collapsible soils of the Brazilian semi-arid region still have IP < 30% and 10% < LL < 50% and the clay activity of these soils varies from low to medium. These soils are collapse-conditioned or truly collapsible; problems in engineering works range from no problems to serious problems; possible damage also ranges from mild to high. The application of direct identification methods confirmed the collapsible behavior of the analyzed soils, however certain indirect methods (GIBBS and BARA, 1962; HANDY,1973) classified the behavior of some of these soils in an unsatisfactory way.

BANKING MEMBERS:
Externa à Instituição - KALINNY PATRÍCIA VAZ LAFAYETTE - UPE
Externa ao Programa - 2984374 - MARIA ISABELA MARQUES DA CUNHA VIEIRA BELLO
Presidente - 1654153 - MARIA ODETE HOLANDA MARIANO