Hong Kong Marine Deposit Improved by Prefabricated Band Drains and Reinforcement

Soft Soils, such as Hong Kong marine deposits (HKMD), are characteristic of high compressibility and low strength. Buildings constructed on soft soil grounds may suffer from excessive settlements, especially post-construction settlement, which are related to creep behavior of soft soils. Accurately predicting long-term settlement and effectively controlling post-construction settlements are of great importance. In recent decades in Hong Kong, deep cement mixing (DCM) technique has been successfully adopted to create inclusions in the form of columns, walls, or grids to reinforce HKMD. Building on this engineering background, the first part of the webinar will focus on the performance of deep cement mixing (DCM) in HKMD and the load transfer between DCM and surrounding soils, drawing from insights gained through laboratory experiments and numerical simulations. However, due to the high costs and carbon emissions associated with the DCM technique, it should be used judiciously. The second part will introduce a two-step ground improvement method using prefabricated band drains in combination with surcharge and/or vacuum preloading to improve dredged HKMD in a cost-effective manner.