Development of flume model of inclined capillary barrier (clay silt/CDW) in a subtropical climate scenario

Thays C.F Oliveira,Bianca G.S Dezen,Julio C Bizarreta-Ortega,T.M.P De Campos,G.F.N Gitirana,M.M.A Mascarenha,F.A.M Marinho

doi:10.1051/matecconf/202133704007

Thays C.F Oliveira, Bianca G.S Dezen + Show 5 more

Open Access

https://doi.org/10.1051/matecconf/202133704007

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Abstract

Interest in research on capillary barrier (CB) in regions with humid climates (tropical and subtropical) is increasing. One of the main advantages of such cover type is the greater flexibility regarding the materials that could compose it. A possibility is the use of construction and demolition wastes (CDW), which would contribute to the solution of CDW destination, a problem in urban centers. Thus, the present work aimed an experimental evaluation of CB cover with CDW in its composition. A CB cover system was reproduced in a physical model in acrylic box, with clay soil as capillary layer and CDW as capillary block, given its granulometric and hydraulic contrast. The layers were arranged with the usual landfill slope, of 1:3, and a very heavy rain, of 90 mm, was simulated. Three tests were performed on the flume model, in which initial CDW saturation degree (S0) was varied in 4,5%, 10,3% and 17,3%. Results indicate formation, indeed, of capillary barrier between the two used materials. The most efficient model was the one with lowest initial CDW S0, of 4,5%. As the CWD S0 increased, time of flow permanence at materials interface decreased, indicating a CWD S0 in which such capillary barriers no longer function effectively. Regarding percolation rate, the maximum for a 90 mm rainfall was 2,7%, which fits the landfill cover projects criteria consulted.

Highlights

The Urban Solid Waste (USW) production in Brazil is annually analyzed and quantified through the cooperation of competent agencies (e.g., ABRELPE and IBGE) along with the Brazilians city halls
The present work was divided in two main stages, where the first was the collect of the materials that were used in the research and its physical and hydraulic characterization, and the second, the development of the reduced physical model for the inclined capillary barrier simulation in subtropical climate conditions
The results of this work indicate that the studied materials are compatible for the associated application in capillary barrier systems, with the use of the soil as the capillary layer and of the construction and demolition wastes (CDW) as the capillary block

Summary

Introduction

The Urban Solid Waste (USW) production in Brazil is annually analyzed and quantified through the cooperation of competent agencies (e.g., ABRELPE and IBGE) along with the Brazilians city halls. Still according to ABRELPE [1], out of this collected quantity, 59,5% of the wastes were sent to landfills This value, when compared to the one of 2007, represents an expressive increase (20,9%) of USW disposition in landfills. In this context, research concerning USW landfills is extremely important, once it is necessary to assure its good functionality, due to the specificities of these constructions, that are being each time more required. One of their main particularities is the final covers systems These are extremely important, especially considering their function of minimize the rainfall infiltration and its percolation into the residues mass. It is important to highlight that the refereed system directly influences in the leachate production and, ideally, they should be constituted by several layers, which are: surface layer; protection layer (that stores percolated water from the superior layer); drainage layer (that promotes the lateral flow of the percolated water); hydraulic barrier layer (which prevents the infiltration of the non-drained water); and, gas collection and foundation layer ([2] and [3])

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