Effect of Electrokinetics on Pullout Resistance of Sheet Pile Walls-Paper

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The study investigated whether electrokinetic (EK) conditioning could reduce the force needed to extract steel sheet piles from clay. Researchers embedded stainless-steel plates in compacted kaolinite and kaolinite mixed with 20% or 30% sand, then measured pullout resistance before and after applying an electric gradient of 1,500 V/m for 20, 40, or 60 minutes.<br /><br />EK treatment reduced pullout resistance in all tested soils. In pure kaolinite, resistance generally fell as treatment duration increased; the authors report a reduction of about 60% after 60 minutes, although individual tests varied. In mixtures containing 20% sand, reductions were approximately 65–75%, while mixtures with 30% sand showed reductions of roughly 77–84%. For both sand mixtures, most of the reduction occurred within the first 20 minutes, with little additional benefit from longer treatment.<br /><br />Pullout resistance was highest in pure kaolinite and decreased as sand content increased. The results suggest that EK conditioning may weaken soil–steel adhesion and make temporary sheet piles easier to extract, potentially reducing extraction forces and the risk of damage. However, the experiments used small laboratory samples, and the effect of treatment duration—particularly in pure clay—was not fully consistent. Field-scale studies are needed to establish the method’s practical effectiveness.

Keywords

electrokinetic conditioning

sheet pile extraction

pullout resistance

kaolinite clay

soil-steel adhesion

electric gradient

stainless-steel plates

sand content

soil weakening

laboratory study