ABSTRACT
A case history is presented to describe the application of the “S-Alpha hydraulic Dive” system for the installation of stone columns offshore. This system comprises equipment able to be dived in the sea up to a maximum water depth of approximately 25 m, allowing to reduce the effective weight of the whole system and thus allowing the execution of deeper treatments of stone columns with dry bottom-feed method until approximately 70 m depth. It is described the soil improvement to support the foundation of one abutment for the San Ignacio bridge built over the Bilbao estuary in Spain. As conclusions, the satisfactory application of the “S-Alpha hydraulic Dive” system for the installation of stone columns offshore in very soft soils is highlighted, as well as the capacity of the improved soil to consolidate and increase the shear strength required to carry out this type of marine works.
