Shear strength behavior of geotextile/geomembrane interfaces

This paper aims to study the shear interaction mechanism of one of the critical geosynthetic interfaces,the geotextile/geomembrane,typically used for lined containment facilities such as landfills.A large direct shear machine is used to carry out 90 geosynthetic interface tests.The test results show a strain softening behavior with a very small dilatancy(<0.5 mm) and nonlinear failure envelopes at a normal stress range of 25-450 kPa.The influences of the micro-level structure of these geosynthetics on the macro-level interface shear behavior are discussed in detail.This study has generated several practical recommendations to help professionals to choose what materials are more adequate.From the three geotextiles tested,the thermally bonded monofilament exhibits the best interface shear strength under high normal stress.For low normal stress,however,needle-punched monofilaments are recommended.For the regular textured geomembranes tested,the space between the asperities is an important factor.The closer these asperities are,the better the result achieves.For the irregular textured geomembranes tested,the nonwoven geotextiles made of monofilaments produce the largest interface shear strength.

A Study on Impervious and Heat-Insulating Performance of Geomembrane Composites Within Breakwater

This paper investigates the performance of geomembrane composites used as impervious andheat-insulating lining within a breakwater for a power station.The seepage field,distribution ofstress-strain contour and seepage discharge of hot water which has been treated as the inner thermalsource in the calculation of heat-insulation,have been given by three-dimensional calculation method coup-ling seepage with stress.The results indicate that the impervious and heat-insulation effect ofgeomembrane composites is significant.

Seasonal variations and the influence of geomembrane liners on the levels of PBDEs in landfill leachates,sediment and groundwater in Gauteng Province,South Africa

In the present study,the seasonal concentrations of polybrominated diphenyl ethers(PBDEs)in leachate and sediment samples,and the influence of geomembrane liners on PBDE levels and the extent of their infiltration into groundwater on selected landfill sites in Gauteng Province,South Africa were determined.Leachate and sediment samples were collected from seven operational landfill sites namely:Goudkoppies,Robinson Deep,Marie Louis,Soshanguve,Onderstepoort,Hatherly and Garankuwa from Johannesburg and Pretoria,in winter and summer.Groundwater samples were collected from monitoring boreholes from two landfill sites.Liquid-liquid and Soxhlet extraction techniques were employed for the extraction of leachate and groundwater,and sediment respectively using dichloromethane.The extracted samples were subjected to column clean up and,thereafter,analysed using gas chromatographyemass spectroscopy(GC-MS).PBDEs selected for the study were:BDE-17,-28,-47,-100,-99,-153,-154,-183 and-209.The P9PBDE concentrations in leachate samples for winter and summer ranged from 0.316e1.36 ng L-1 and 0.560e1.08 ng L-1 respectively.The P9 PBDE concentrations obtained for sediment in winter and summer were 3.00e4.91 ng g-1 and 2.50e3.71 ng g-1 respectively.Winter samples exhibited higher(p<0.05)concentrations for both leachate and sediment samples compared to summer samples.This trend was attributed to high precipitation rate in summer which may have infiltrated into the landfills,subsequently diluting the leachate and sediment samples.In contrast,the winter period is generally dry and PBDEs are,therefore,more likely to be concentrated.The concentrations of PBDEs in leachate and sediment samples were higher in landfill sites with geomembrane liners compared to those without liners.Groundwater samples taken from the vicinity of selected landfill sites without geomembrane liners exhibited high concentrations of P9PBDEs,indicating possible migration of PBDEs from landfill site into groundwater.Pearson correlation(r)and statistical significant t-test(p)for the PBDE congeners versus dissolved organic carbon(DOC)resulted in positive moderate interactions with a statistical significance for most congeners.Suggesting that there is a possible influence of organic carbon on the levels of PBDEs.

Construction Technology of Biodigesters in Senegal

Faced with the depletion of fossil energy resources and given the current context of the fight against climate change, Renewable Energies (RE) represent an increasingly growing challenge. Of all these energies, those resulting from the biomethanization of biomass now provide an opportunity in the world of farmers and breeders. The treatment of agro-pastoral residues by anaerobic digestion has been the subject of renewed interest in recent years, thanks in particular to the production of energy from biomass, not to mention the production of fertilizers from effluents. Expelled from the digesters. This method of transformation offers many environmental, socio-economic and agricultural interests. Indeed, the biogas obtained from organic matter allows, among other things, to cook, light houses, and produce electricity and heat. The objective of this study is to compare the construction techniques and costs of the biodigester models that exist in Senegal. There are many biodigesters, the choice of an installation depends on the available space and the nature of the soil. Several types of biodigester technologies are installed in Senegal. The GGC 2047 fixed dome, the RMB geomembrane and the BEG geomembrane. First we will describe the construction techniques of the modified GGC model fixed dome biodigester, then of the RMB model geomembrane and finally of the BEG model geomembrane.

西霞院反调节水库复合土工膜摩擦系数研究

复合土工膜广泛应用于土石坝、河道整治的滤层防渗,滤层中加入了土工膜后,其间的摩擦系数变化较大,直接影响到工程的抗滑稳定.针对土工膜与土体接触的多种情形,研究证明了土工膜与接触料之间的摩擦系数小于接触料自身的摩擦系数,土工膜横丝向的摩擦系数大于顺丝向的摩擦系数,及土工膜与接触料之间的摩擦系数与接触料的颗粒级配及饱水状态有关,此结果可为同类工程参考.

Suitability of Irbid Clay as Compacted Liners for Landfill, Jordan

The goal of this study is to investigate the possibility of using the Irbid city clayey soil as compacted clay liner. The geotechnical properties and the permeability characteristics of compacted clayey soil sample obtained from the eastern part of Irbid city were determined to evaluate their suitability as compacted clay liner. Falling head permeability test, unconfined compressive strength and volumetric shrinkage test were conducted on soil samples that were compacted at about 0% and 3% wet of its optimum water content. The leakage rates expected through clay-only and composite geomembrane-clay liners were determined. It could be concluded based on the results of the geotechnical tests and leachate rate calculations that Irbid clay is appropriate to be used as compacted landfill liner material.