Vibration effect influence upon non-aqueous phase liquid migration in double-porosity soil

Natural disasters such as earthquakes, El-Nino, tsunamis and water pollution have a negative impact on human health and living environment. Some of these may give rise to subsurface vibrations that can potentially increase groundwater pollution risks in double-porosity systems. The more complicated situation was where underground storage tanks and petroleum pipeline damage have caused the leakage of non-aqueous phase liquids (NAPLs) which migrated into the groundwater resources. These problems need to be addressed by both professionals and researchers worldwide to ensure the sustainability of groundwater utilization. This paper aims to investigate and understand NAPL migration in vibrated double-porosity soils. To do so it was necessary to study the phenomena and characteristic of soil structure and the pattern of NAPL migration to identify cost-effective remediation schemes. A laboratory experiment was conducted to study the phenomena and characteristics of vibration response and NAPL migration in double-porosity soil deformation under vibration effect using a digital image processing technique (DIPT). The outcomes of the experiment show that the gradual increase of vibration table excitation frequency yielded different vibration responses from the respective soils. This indicated that soil surface acceleration depended significantly on the soil conditions, soil water content, soil structure and the pattern of soil fracturing. NAPL migration was faster in sample 2 with 150ml toluene than sample 1 with 70ml toluene and this could be because the greater amount of toluene in sample 2 exerted an extra entry force on top of the soil sample that had yet to migrate through the sample surface. Finally, it was concluded that the DIPT may provide detailed information, and can be used to understand and identify the remediation method as well as to ensure the sustainable consumption of groundwater.