Current Trends for Heavy Structures and Urban Environments-PPT Presentation

PPT Presentation

Pdf Summary

The presentation reviews current foundation and ground-improvement methods for heavy structures in urban environments, focusing on cast-in-place piles installed by single-pass rotary drilling. It distinguishes augercast/CFA piles from intermediate and full-displacement piles, and traces augercast pile development from early patents in 1959 through advances in hollow-stem grout placement and larger pile sizes.<br /><br />Modern APG/CFA piles can reach 48-inch diameters, potentially 60 inches, and depths approaching 200 feet. Case studies describe their use for high-rise buildings, bridges, transportation projects, and other heavy structures, with substantial design and tested compression capacities. Displacement tooling can also install pile groups and ground-improvement elements.<br /><br />Displacement installation may densify loose-to-medium sands and increase horizontal stress, with improvement accumulating as more elements are installed. Evidence for benefits in soft fine-grained soils is less conclusive. The presentation contrasts this behavior with rigid inclusions, where grout columns support loads within a soil matrix and improvement is considered global rather than a change to the soil between elements. Other methods discussed include grout columns, stone or aggregate systems, and augered elements.<br /><br />Examples include liquefaction mitigation using thousands of displacement elements across a site, as well as ground improvement beneath building footings. At the Revel Casino, structural APG piles were combined with shallower displacement elements between piles to improve lateral resistance.<br /><br />Automated monitoring and “measuring while drilling” record installation data such as depth, penetration and withdrawal rates, rotation, hydraulic pressure, and grout flow. Incremental and cumulative installation indices can help characterize soil conditions and relate construction records to pile performance.

Keywords

foundation methods

ground improvement

augercast piles

continuous flight auger

displacement piles

deep foundations

liquefaction mitigation

rigid inclusions

measuring while drilling

urban heavy structures