DSM SOE and Base Plug Systems on the Beach-PPT Presentation

PPT Presentation

Pdf Summary

The project involved constructing a 52-story oceanfront tower in North Miami Beach, Florida, between existing high-rise buildings. The site’s challenging soil profile included permeable sand, peat, weak limestone, and competent limestone. The tower and garage required excavations to different depths, with deep foundations consisting of 3-foot-diameter auger-cast piles.<br /><br />Key challenges included controlling groundwater in highly permeable sands with a high water table, managing different excavation levels, and limiting nonuniform settlement. The design used a deep soil mixing (DSM) plug and gravity bulkhead as temporary support for the tower excavation. DSM elements were designed to withstand construction-stage compression and uplift, with particular attention to potential cracking near the transition between the tower and garage. Perimeter support also used cantilevered steel beams; garage excavation was restricted until the tower reached the tenth floor.<br /><br />Analysis evolved from a simple approach to sophisticated finite element modeling that incorporated actual geometry, individual columns and foundation elements, loading, and construction sequence. The model also supported quality-control assessments by evaluating stresses in individual elements. Closed-form checks were used to verify the analysis.<br /><br />Project success depended on understanding and following the construction sequence, coordinating responsibilities for temporary and permanent conditions, and maintaining close attention to detail. Monitoring showed maximum lateral movement of about 1 inch at the perimeter support wall and approximately 0.6 inches of downward movement at adjacent buildings; no damage was reported.<br /><br />The project demonstrated that complex construction conditions warrant detailed analysis and that effective coordination, sequencing, and monitoring are essential to successful DSM-supported excavation.

Keywords

oceanfront tower

North Miami Beach

deep foundations

auger-cast piles

groundwater control

deep soil mixing

temporary support

finite element modeling

construction sequencing

excavation monitoring