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The design of reinforced soil is usually based solely on the mechanical properties of the fill, in the case of new structures, or the soil in the case of soil nailing. All soils display electrokinetic properties but these have largely been ignored in geotechnical design. The development of electrokinetic geosynthetic materials, which act as both electrodes as well as providing the established geosynthetic functions, has made it possible to combine the electrokinetic and mechanical properties of soils in geotechnical design. Using this approach, it is possible to improve the mechanical properties of the soil or fill prior to or during construction. The objective of the electrokinetic improvement is to increase the availability of suitable fill or make soils/waste materials previously not suitable for soil reinforcement acceptable and hence extend the application of reinforced soil. The use of computer-controlled electrokinetic treatment has resulted in effective and economic design and construction protocols, which in turn have led to a growing number of applications which provide positive evidence of the economic and environmental benefits of combining both the electrokinetic and mechanical properties of the soil in the design of reinforced soil structures. [ABSTRACT FROM AUTHOR]

An electrokinetic geosynthetic (EKG), is a polymeric geosynthetic material, enhanced to conduct electricity, which can be used to transport water in fine-grained soils by electrokinetic means. This paper describes the design, construction details, and analysis of a reinforced soil wall using EKG and wet cohesive fill. In order to establish an initial design layout, a long-term stability analysis of the wall was carried out using the soil’s critical state shear strength parameters. The long-term design was then checked for short-term stability based upon a minimum required undrained shear strength for the clay utilizing four different short-term analytical methods: critical height, Coulomb, discrete theory, and composite theory. The electroosmosis design was then undertaken, based upon the water content—undrained shear strength curve for the fill material ascertained from laboratory testing. Using this curve the difference between the as-placed water content and the water content corresponding to an undrained shear strength of 20 kPa was calculated, giving the volume of water that needed to be removed from each lift of clay fill. Using this volume of water the electroosmosis calculations were undertaken. A simplistic analysis was undertaken using a linear voltage gradient and fixed soil parameters, followed by a more complex analysis using finite difference techniques to establish the voltage gradient. The variation in the value of electro-osmotic permeability ke were estimated using both an empirical model and a graphical interpretation of the actual variation of ke measured in the laboratory. The results of these analyses yielded estimated treatment times and undrained shear strength of the clay. [ABSTRACT FROM AUTHOR]

Many mining operations produce tailings that dewater very slowly under self-weight consolidation. One way of reducing the water content of such tailings is by electroosmotic dewatering. Although the technique has been used with some success in civil engineering applications, it is still largely seen as a solution of last resort. This is probably due to the high energy costs reported in the literature, as well as problems of very rapid corrosion of metal electrodes. This paper describes a study using newly developed electrokinetic geosynthetics (EKGs) as electrodes for the in situ dewatering of mine tailings. Laboratory tests were undertaken on mineral sands tailings in both a purpose-built testing cell and a laboratory testing tank using EKGs, followed by an outdoor experiment in a tank containing approximately 9 m3 of the tailings. This test was run for over 2 months. Energy consumption in the outdoor test was less than 1 kWh per dry tonne of material dewatered and there was no sign of electrode deterioration even after 2 months of usage. The results point to a potentially powerful technique for reducing the water content of tailings ponds in situ, thus increasing storage space, improving stability, and facilitating closure of these facilities. [ABSTRACT FROM AUTHOR]