Electrokinetic Geosynthetic Stabilisation of Failed and Failing Slopes

Electrokinetic Geosynthetic Stabilisation of Failed and Failing Slopes - Practical Issues

Jones, C.J.F.P. / Lamont-Black, J.

Failures of cut and embankment slopes are common and expected to increase. Conventional repair techniques include, acquiring additional land, reducing the slope angle, installing drainage improvements, soil nailing, and or, providing structural support. All of these methods have technical limitations and can be costly. New stabilisation options are becoming available which are more effective and economical than traditional approaches. Amongst these is electrokinetic geosynthetic (EKG) treatment of failing or failed slopes. The benefits of EKG treatment of slopes include reduced cost and reduced environmental impact. The theory of electrokinetic treatment of failed and failing slopes has been considered by a number of authors. The practical issues associated with the technique are less well appreciated. The paper provides a brief description of the EKG treatment method and considers some of the practical issues associated with the technology. The lower cost of EKG slope treatment is due to the reduced engineering elements associated with the technology compared with other stabilising methods. In addition, the treatment is gradual, only acts when the current is switched on and does not induced rapid changes in ground conditions including settlement. The treatment can be flexible in approach by varying the voltage, electrode spacing and duration. Further flexibility is possible by manipulating the electrode array and angle of electrode installation to accommodate in situ obstacles such as trees. Sustainability benefits include reduced carbon footprint and elimination of the use of primary aggregates. EKG treatment requires fewer heavy goods vehicle movements, minimal material import, reduced noise, preservation of the environment and minimum vegetation clearance with almost all trees being retained. Figure 7 shows the condition of an EKG repair to a failed highway slope supporting the A21 trunk road south of London one year after the work was completed. Dormice, an endangered species, returned to the site within a year.