Geosynthetics: Innovative Materials And Rational Design

Geosynthetics have revolutionalized many aspect of geotechnical design and construction. Modern geosynthetic engineering involves identifying the function(s) of the geosynthetic in a given application, establishing the required engineering properties based on rational design methodologies, and selecting a cost effective solution that meets the engineering requirements. When appropriately designed and installed, geosynthetics provide a cost effective alternative to more traditional techniques. This paper highlights a few examples. The potential for Geosynthetic Clay Liners (GCL's) serving as an alternative to a conventional compacted clay liner or as a means of augmenting the performance of a compacted clay liner as part of a composite liner system in the base of municipal solid waste landfills is examined. It is shown that basal reinforcement can be an efficient and effective means of allowing the construction of embankments over soft soil deposits. It is noted that while basal reinforcement can increase stability and reduce short term shear deformations, it can not prevent long term consolidation and creep settlements. However when the use of basal reinforcement is combined with the use of prefabricated vertical drains, it is possible to reduce long term deformations by appropriate surcharging of the soft deposit. Using geosynthetic reinforcement to support structures over man-made or naturally occurring voids is a developing application. How to design for this condition is the subject of current studies, and it can be shown that strong stiff reinforcement is efficient and effective and that multiple layers of extensible material of medium strength can also be used. Recent developments in composite materials include reinforcement with inbuilt drainage; these have been shown to accelerate the reduction in porewater pressure and permit more rapid construction of reinforced embankments using poor quality fill. Further developments include a new range of geosynthetic materials which are electrically conductive.