Avaliação da granulometria de materiais de filtros para obras de terra

Evaluation of the granulometry of filter materials for earthworks

Abstract

The percolation of a fluid through the soil is related to the ability to relieve the stresses of an earthwork. The certification of the classical criteria of permeability and retention in dam filters allows analysis of filtration mechanisms, colmatation of fines soils, particle infiltration and transport. Thus, this research highlights the difference of the percolation behavior in different base materials, being soil 1 with more than 60% of clay fraction, soil 2 with predominance of silt as a fine portion, soil 3 with sandy characteristic, and mining tailing, for two types of filter material, with 90% and 60% of sand fraction. Given the performance of permeability, combined percolation, suspended and total solids tests, analysis of materials interactions allowed to observe, among other discussions, that the use of a more open granulometryas a filter material did not satisfy the retention criteria for base materials with silty characteristics, but when combined with high clay fraction base materials, their larger voids did not favor the transportof particles. It was concluded that the best graded sand is suitable as a filter material for drainage of earthworks that use any of the four types of base materials studied, given ideal design practices.