Underpinning and strengthening of an existing port infrastructure to allow the installation of a high-capacity vessel synchrolift

The installation of a high-capacity vessel synchrolift within a port infrastructure located in a high seismic region imposed significant structural challenges. The project involved substantial load increases and seabed dredging of approximately 8 m beneath the foundation level of the existing gravity-type block quay walls. In addition to extensive dredging, underpinning and strengthening of the quay walls were required, along with the construction of high-capacity complementary structures designed to interact with both the soil and the existing infrastructure. These improvements ensured their ability to support the increased loads from vessel-lifting, onshore transfer, and dry-docking operations of up to 9,000 ton vessels. This chapter outlines key design principles and the sensitivity analysis procedures, highlighting local constraints and their influence on the cost-benefit analysis that led to the adopted technical solutions. It also provides a summary of the construction sequence, emphasizing the importance of meticulous project timeline planning. A thorough analysis of design and construction variables proved to be indispensable to successfully achieve an unconventional underpinning and strengthening solution in a complex geotechnical environment, by means of technical systems that permitted a substantial dredging under the foundation level of an existing infrastructure, while significantly enhancing its resistance in compliance with current regulations.