Unsaturated geotechnics applied to geoenvironmental engineering problems involving geosynthetics

Movement of fluids in the unsaturated zone plays an important role in many geoenvironmental engineering problems. Examples include cover and basal liner systems for waste containment facilities where geosynthetics are widely used, amongst many other examples. This paper highlights the importance of assessing the unsaturated characteristics of geosynthetics and their influence on the behaviour of engineered systems where soils and geosynthetics interact under unsaturated conditions. It includes information on the water retention curve and hydraulic conductivity function of geosynthetics such as geotextiles and geosynthetic clay liners (GCLs) with particular focus on capillary barriers, liner performance under elevated temperatures, and interface friction respectively. Mechanisms involved in the development of capillary barriers are evaluated to explain the storage of water at the interface between materials with contrasting hydraulic conductivity (e.g. a fine-grained soil and a nonwoven geotextile). Potential desiccation of GCLs is explained in the light of an application in a liquid waste impoundment.

► The water retention curve of geotextiles shows a highly nonlinear response. ► Water retention curve of GCLs seems to be dependent on manufacturing process. ► Geosynthetic capillary barriers may benefit a number of environmental geotechnics applications. ► Hydraulic performance of GCL subjected to high temperatures depends on its water retention curve. ► Greater effective stress associated with higher suctions improves soil geosynthetic interaction.