Investigation of Soil Consolidation for The Combined Technique of Electro-osmosis and Preloading

: Discovered in the 19 th century, electrokinetic phenomena has been researched extensively over the past few years. Recently, need for additional land within large cities has led to the reclamation of areas once deemed undesirable and filled with sludge. This has increased the desire to understand the process of electro-osmosis as a method of ground improvement in coastal areas undergoing rapid expansion. Electro-osmosis has several advantages over other methods of ground improvement, some of these include; reduced equipment on the construction site, lack of reliance on particle size of soils, permanent effects etc… However, while electro-osmosis possesses several advantages, it continues to lag in use due to a lack of proper standardised testing as well as large discrepancies between analytical solutions and in-situ results. To enhance the effects and efficiency of electro-osmosis, while lowering electrode corrosion, surcharge was added to electro-kinetic process for one-dimensional, two-dimensional and hexagonal one-dimensional electrode arrangements. Furthermore, a self-made box (60cm*45cm*45cm) with cathode electrodes made of synthetic plastic wrapped with steel wire was incorporated. An spd-3606 DC power supply was used to apply 25V to the soil sample. The desired water content percentage of each experiment was roughly 70%, and total experiment time was 72 hours. The cumulative discharge, drainage rate, water content (upper and subsoil layers), deformation and cracks were observed. The data presented in this study focusses on better understanding the mechanisms contributing to the consolidation and deformation (vertical and horizontal) of soft soil under the combined method of electroosmosis only and electro-osmosis with loads. It was observed that largest discharge volume of expelled water (40546.59 ml) occurred during electro-osmosis combined with surcharge coupled with two-dimensional electrode arrangement. The lowest cumulative discharge (11856.42 ml) was observed under the hexagonal one-dimensional electrode arrangement with electro-osmosis only. Furthermore, 2682.64 ml/h was the highest calculated drainage rate which occurred in experiment M2 (electro-osmosis combined with surcharge for two-dimensional electrode arrangement) after 20 hours of experiment time. While the water content readings were all lower than the initial percentage, the electro-osmotic phenomena resulted in an uneven distribution of water content percentage within the soil mass. Additionally, largest average vertical deformation within the soil mass occurred in one-dimensional electrode setup combined with surcharge (46.58mm). Each electrode arrangement yielded different crack patterns and sizes. However, compared to electro-osmosis only, reduction in cracks was evident under each of the combined method experiments. It is concluded that Improvement in electro-osmotic efficiency with regards to drainage rate, cumulate drainage, water content and deformation was observed in the combined method of electro-osmosis with loads. Furthermore, the electro-osmotic improvement did not solely depend on the loads, but also depends on electrode arrangement.