Overview

EKG Geochemical Soil Improvement

Environmental Sustainability

EKG slope stabilisation system

Unstable embankments and cuttings represent a major problem for railway and highway authorities. In the majority of cases slopes in soils fail or become unstable owing to a number of factors including:

• Weak soils

• Excessive pore water pressures

• Over steepened slopes

• Excessive external loadings

There are a large variety of engineering solutions to slope instability, which tackle various combinations of factors. EKG slope stabilisation methods have been developed to provide a light engineering approach, that is both economic and effective, by concentrating on the factors of soil strength and drainage.

• Improving the strength of the soil material
- consolidation
- electrochemical osmotic treatment

• Reinforcing the soil mass
- electrokinetic soil nails
- electrokinetic geogrid

• Providing drainage
- active electroosmotic drainage
- passive hydraulic drainage

The EKG system comprises four methods of slope stabilisation, applicable to different geotechnical settings, which select different elements of the above. A brief outline is provided below, for more detail please follow the links.

Electrokinetic processes in the ground include an electroosmotic flow from the anodes to the cathode, a reduction of pore pressure around the anode, cementation around the anode and precipitation around the cathode.

Method 1
Electrokinetic ground improvement and reinforcement with active and passive drainage

Slope stabilisation using electroosmosis where anodes and cathodes are used in the active (electrokinetic) phase to force water out of the ground resulting in an improvement in the material strength of the soil. After active treatment the anodes are reinforced and converted to soil nails and benefit from a major improvement in the frictional and adhesion components of the soil / reinforcement bond strength. The cathodes are left in place in the slope to act as long term drainage.

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Method 2
Reinforced soil with EKG

EKG material in the form of conductive geogrid may be used to construct reinforced fill using very poor material. The embankment may be constructed in a series of layers or lifts wherein the EKG materials first act to dewater, then strengthen and drain the material. The EKGs are then left in place to provide the long term functions of reinforcement and pore pressure relief. The major advantage of this method is that it permits the construction of steeply inclined soil structures using very poor quality material, so poor in fact that the ‘soil’ may be poured into place during construction.

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Method 3
Counterfort drains with EKG

EKG material in the form of an electrically networked filtration blanket is used to overcome surface barriers to hydraulic flow which can dramatically reduce the performance of counterfort and trench drainage systems in reducing the pore pressures in cuttings slopes. The system requires only modest power input and can be run from a renewable source such as wind or solar power. This system can be applied to newly constructed counterfort drains. Existing, poorly functioning counterfort or trench drains can also be rejuvenated using EKGs.

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Method 4
Electrokinetic geosynthetics and chemical treatment

Electroosmotic chemical treatment is a method of changing the plasticity and improving the shear strength characteristics of fine grained soils by using EKG materials to introduce and migrate chemical conditioners or agents into and through the soils to effect changes in plasticity and or deposit cementitious material in pore spaces. The method borrows techniques and understanding developed from in situ soil treatment techniques including electrochemical remediation and soil stabilisation (e.g. with lime). The method is aimed at high plasticity soils and those in which the failure surface is relatively deep and or well defined. Examples of the potential applicability would be large landslides where reinforcement or structural solutions are either impractical or prohibitively expensive.

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