Volume 8, Issue 3

September 2023

Case History

Permanent Basement Walls with Pressed-in Sheet Piles
in Portland, Oregon, U.S.A.
Takefumi Takuma
Senior Advisor
Giken America Corp.

Steel sheet piles are utilized as temporary as well as permanent earth retaining elements. As a matter of fact, a sheet pilewall can be designed and built to function in both ways to achieve faster construction with lower project cost. Some ofthe new multi-unit residential and office buildings in the U.S. are built with sheet pile basement walls instead of moretypical concrete-based walls, such as diaphragm and secant pile walls. Sheet pile basement walls come with the following
advantages in many cases.
Simpler design and construction with a choice of a cantilevered, braced, or anchored wall.
More flexible choice for a basement construction sequence among top-down, bottom-up, or hybridof both.
Narrower wall footprint, i.e., larger inner space of a basement. See Fig. 1.
Can be designed to bear vertical loads, which likely reduce the size or the number of vertical loadcarrying columns.
Can achieve watertightness with sealing or welding of interlocks.

Fig. 1. Larger inner apace with sheet pile wall than with secant pile wall
(Base drawing: Nucor Skyline)
Fire resistance should be attained with intumescent paint coating or placement of insulating panels, curtain walls, orconcrete. Some sheet piles have been tested to meet applicable codes and standards.
A large-scale urban redevelopment project in Portland, Oregon in the U.S.A. took advantage of the sheet pile wallbasement structure with the footprint of 140m x 61m. The 2018 project built 380 apartment units, 1,900m2 of groundlevel retail space, and two levels of underground parking structures for 602 parking spaces on two city blocks. See Fig. 2for an architect’s rendering of one of the buildings. Due to its proximity to nearby buildings, a tight installation tolerance,and hard soil conditions with gravel and cobbles below a certain depth, press-in piling with an auger attachment wasadopted as shown in Fig. 3. Excavation followed press-in piling as shown in Fig. 4 and tie-backs were installed for furtherexcavation. Fig. 5 shows a basement garage with sheet pile walls of a different project as an example.
ArcelorMittal provides reference materials on this type of underground structure at the following link.
https://sheetpiling.arcelormittal.com/applications/underground-car-parks/

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September 2023

Acknowledgement
The author appreciates assistance provided by Dennis Guimond, a retired employee of Nucor Skyline, Blake Patsy of KPFF
Consulting Engineers, Chris DellAringa and Taylor Stevenson of Blue Iron Foundations and Shoring LLC, and Ian Vaz ofGiken America Corp.

Fig. 2. Architect’s rendering of Conway Block 294E Building in Portland, Oregon(https://cairnpacific.com/block-2945-e)Fig. 3. Press-in piling with auger attachment(Photo: Blue Iron Foundations and Shoring LLC)

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Fig. 4. Press-in piling (far right) followed by excavation(Photo: Blue Iron Foundations and Shoring LLC)

Fig. 5. Example of completed basement with sheet piles (different project)17