Sustainable land reclamation using locally dredged marine soils and wastes: practice and theory

Due to the excessive pressure of land supply for housing and economic development, there is an urgent demand for land reclamation, especially in Hong Kong. The current challenges in land reclamation include high cost, long construction time and shortage of fill materials such as sea sands. This chapter introduces a sustainable approach to land reclamation by utilizing local marine deposits and industrial/construction wastes as fill materials. A combined reclamation method using horizontal and vertical drains with vacuum preloading and surcharge to improve the dredged and existing soft marine deposits is described, including evidence from laboratory model tests and a field trial study in Hong Kong. A novel sustainable binder with incinerated sewage sludge ash and recycled industrial waste for solidifying soft marine deposits is presented. The use of marine deposits and wastes can significantly reduce the costs, construction time and environmental impacts of large-scale reclamations. To enable settlement prediction and control of the marine deposits, a new simple hypothesis B method based on the elastic visco-plastic model has been developed, verified and applied for multi-layer soft soils, which are also presented in the chapter.