Sustainable ground improvement and hybrid foundation for tank farm on liquefiable coastal deposit: Case study
Abolfazl Eslami, Amirhossein Ebrahimipour, Seyed Mohammad Fattahi, Amin Omrani Rekavandi, Alireza Moazzami, Kiarash Khoshbakhty
Abstract
Coastal deposits, often weak and young soils with high groundwater levels, pose significant geotechnical challenges, particularly under seismic loads that exacerbate liquefaction risks. This study examines a sustainability-driven approach to ground improvement and foundation design for a coastal tank farm. In-situ and laboratory tests identified the depth and extent of liquefiable layers, leading to the selection of deep dynamic compaction as the most sustainable technique, considering economic, environmental, and social criteria. Using tampers weighing 11 and 23 tons dropped from heights of 18–28 m in square patterns with 2 and 5 m spacing, the ground was successfully compacted. SPT, PLT, and field density tests demonstrated the method’s effectiveness, showing a 15% increase in dry unit weight, a 13% rise in relative density, and complete mitigation of liquefaction potential. Two foundation systems, a raft and a hybrid semi-deep ring foundation were evaluated. The hybrid foundation system proved superior in bearing capacity and settlement performance while reducing concrete usage by substituting confined natural geomaterials. This approach minimized the carbon footprint and advanced sustainability in geotechnical design.