Assessment Of Water Salinity Effect On Physical Clogging Of Synthetic Drainage Envelopes By Permeability Tests

In this study, a gradient ratio test which is one of the methods used in the laboratory to evaluate the clogging potential of soil-synthetic envelope systems was applied. For this purpose, two physical models of permeameters (designed by ASTM D-5101) were used to carry out a series of permeability tests by applying water with different salinities and five different PLMs (pre-wrapped loose material). To simulate real conditions, soil and water were collected from the Khorramshahr drainage project area located in Khuzestan province (south of Iran) which has been significantly encountering the common trouble of water and soil salinity. Therefore, saline drainage water (EC =22.2 dS m(-1), SAR =26.27 (meql(-1))(0.5)) in comparison with low salinity water (EC =0.78 dS m(-1), SAR =1.23 (meql(-1))(0.5))) were considered in this research. Permeability tests were carried out at five different hydraulic gradients (1, 2.5, 5, 7.5, and 10) according to the standard method. Variations of system permeability and gradient ratios were investigated statistically as factorial experiments in the form of a randomized complete design. Based on the permeability test results, hydraulic conductivity and gradient ratio of all PLMs were susceptible to the salinity of the water utilized in permeability tests. Based on the results of all gradient ratios, the probability of clogging by applying saline water was higher. Copyright (c) 2014 John Wiley & Sons, Ltd.RESUME Dans cette recherche, le test du ratio de gradient (ASTM D-5101) a ete utilise en laboratoire pour evaluer le potentiel de colmatage d'un systeme de filtration du sol/geosynthetique. A cette fin, deux modeles physiques de permeametre (concus selon la norme ASTM D- 5101) ont ete utilises pour faire une serie d'essais de permeabilite en faisant varier le type de geosynthetique et la salinite de l'eau. L'etude a ete realisee sur le sol et l'eau qui ont ete collectes depuis le sud de l'Iran (Khorramshahr) en utilisant cinq differents enrobages de PLM (geosynthetique non tisse lache). Un point caracteristique de cette recherche est l'application d'eau de drainage avec une salinite elevee, qui est une difficulte commune a de nombreux projets de drainage dans le sud de l'Iran (EC =22.2 dS m(-1), SAR =26.27 (meql(-1)) 0.5) par rapport a l'application d'eau normale (EC =0.78 dS m(-1), SAR =1.23 (meql(-1)) 0.5)). Les essais de permeabilite ont ete effectues a cinq gradients hydrauliques differents (1, 2.5, 5, 7.5, et 10). Les variations de debit, la conductivite hydraulique et le rapport de gradient (defini comme le rapport entre le gradient hydraulique dans le systeme de filtration du sol/geosynthetique au gradient hydraulique dans le sol seul) ont ete mesurees et analysees de facon statique comme des plans d'experience factoriels complets. Les resultats des tests de permeabilite montrent que le colmatage de l'enrobage geosynthetique croit avec a la salinite de l'eau. Copyright (c) 2014 John Wiley & Sons, Ltd.