Interface resistance-based design method for electro-dewatering: Experimental and in-situ data analysis

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In the application of electro-osmosis for the dewatering of soft soil, intermittent current (IC) is commonly used to reduce energy consumption and enhance drainage by adjusting two key parameters: the duration of power cycles and the power on/off ratio. However, the IC mode lacks a reliable design method, leading to ambiguity in determining crucial power parameters and thus cause the waste of energy. In this study, changes in soil-electrode interface resistance during IC are investigated, and a design method for power schemes is proposed based on these findings. A series of indoor experiments with varying power on/off ratios were conducted to analyze their effects on interface resistance, and corroborated by electro-osmotic efficiency indexes such as discharge water volume and current. Field monitoring of interface resistance variation during IC was also performed at a ground improvement project in Zhuhai, China. The results show that the suitable application of IC reduces the interface resistance between soil and electrodes, thereby effectively increasing the electro-osmotic efficiency. Suitable power parameters lead to a decrease in interface resistance when power is restored, but excessively long power-off intervals or improper duration of power cycles can have the opposite effect, causing an increase in resistance. Therefore, selecting optimal power parameters is crucial in IC mode. Based on insights gained from indoor experiments, the electroosmotic drainage will be reflexed by variations in interface resistance. Consequently, this paper proposes a design method for selecting IC parameters grounded in interface resistance, as well as assessing the applicability of the current parameters. Furthermore, continuous field monitoring of interface resistance substantiates the feasibility of this approach, offering guidance for the design of the IC method in soft soil electro-osmosis.