Non-aqueous phase liquid behavior in the subsurface: Transportation, source zone characterization and remediation

Contaminant behaviour in soils and fractured rock is very complex, not least because of the heterogeneity of the subsurface environment. For non-aqueous phase liquids (NAPLs), a liquid density contrast and interfacial tension between the contaminant and interstitial fluid adds to the complexity of behaviour, increasing the difficulty of predicting NAPL behaviour in the subsurface. This paper outlines the need for physical model tests that can improve fundamental understanding of NAPL behaviour in the subsurface, enhance risk assessments of NAPL contaminated sites, reduce uncertainty associated with NAPL source remediation and improve current technologies for NAPL plume remediation. Four case histories are presented to illustrate physical modelling approaches that have addressed problems associated with NAPL transport, remediation and source zone characterization. © 2006 Taylor & Francis Group, London.

The effect of hole size upon the strength of metallic and polymeric foams

Tensile and compressive tests have been performed on centre-hole panels, made from three types of metallic foams and two polymeric foams. In compression, the foams fail in a ductile, notch-insensitive manner, in support of a "net section strength" criterion. In tension, a ductile-brittle transition is observed for some of the foams at sufficiently large specimen sizes: for a small hole diameter the net section strength criterion is obeyed, whereas for a large hole a local stress criterion applies and the net section strength is reduced. For a number of the foams, the panel size was not sufficiently large to observe this ductile-brittle switch in behaviour. The predictions of a cohesive zone model are compared with the measured strengths and are found to be in good agreement. © 2001 Elsevier Science Ltd. All rights reserved.