Predicting Hydraulic Conductivity of Compacted Lateritic Soils: A Reliability Approach

 

Charles Malachy Okechukwu Nwaiwu

Department of Civil and Water Resources Engineering,
University of Maiduguri, Maiduguri, Borno State, Nigeria
E-mail: nknwaiwu@yahoo.co.uk

Joseph O. Afolayan

Kolawole ‘Juwonlo Osinubi

Department of Civil Engineering , Ahmadu Bello University
Zaria, Kaduna State, Nigeria

ABSTRACT

First-order reliability method (FORM) initially developed for structural reliability applications, was employed in the analysis of hydraulic conductivity of compacted lateritic soils as landfill liners. The analysis, which involved the use of a predictive model developed from laboratory data, was used to estimate hydraulic conductivity (permeability) at various reliability levels for three compactive efforts. Results of the analysis show that, for any given compactive effort, the prediction model leads to increasing hydraulic conductivity as the reliability index augments at fixed values of degree of saturation, plasticity index and clay content. On the other hand, for a given reliability index, the hydraulic conductivity decreases when the initial degree of saturation and plasticity index increase. A methodology for selecting soil compositional and compaction variables which enhance reliable soil liner construction is proposed.

Keywords: Compacted lateritic soils, Hydraulic conductivity, Landfill liners, Reliability analysis, Reliability index, Soil composition

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