Comportamento ambiental e geotécnico da disposição de sedimento de dragagem em sistema geotêxtil fechado

Abstract

This study presents a geotechnical and environmental characterization of sediments and waters from the Tijuca lagoon that needs to be dredged and belongs to the Jacarepaguá lagoon complex located in the coastal zone of Rio de Janeiro. Thereafter, a dredging mud with a solids content of 10% was produced and the polymer conditioning was performed for the laboratory experimentation in 09 mini Closed Geotextile Systems. The processes of manual and pumped filling are discussed through environmental and geotechnical parameters of the percolates generated and the sediment cakes retained. It was found that the closed geotextile system has a suspended solids retention efficiency greater than 98.7%. The nutrient, phosphorus and nitrogen, contents of the percolate were reduced by 94.1% and 55.1%, respectively. Parameters such as pH, Eh and CEE increased with respect to the original mud, but are close to the characteristics of the lagoon water. With respect to the sediment cakes retained, a shear strength of 16.0 kPa was observed after 40 days of the last filling cycle, when the solids content was higher than 40%, corresponding to an approximate moisture of 150%. Several correlations with acceptable levels of reliability have been obtained and can be used in the design of preliminary projects with closed geotextile systems technology.