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GOOD SAMARITAN HOSPITAL
PUYALLUP, WA

Permanent Top-Down Shotcrete with
Permanent Soil Nails

The Good Samaritan Hospital in Puyallup, Washington required a West Wing Addition with a 30-ft excavation in loose fill on a crowded site immediately adjacent to the existing hospital and pedestrian walkway. The General Contractor for the project, DPR Construction, hired the design-build team of Ground Support PLLC and Malcolm Drilling Company Inc. to devise a cost-effective soil nail shoring system that would mitigate the cut face instability associated with the loose fills and yet address all of the design and site constraints.


View of Northeast end of shoring walls adjacent to existing hospital facility.

PROJECT DATA AND REQUIREMENTS
  • Permanent top-down shotcrete and epoxy-coated soil nails, 7,500 square feet of wall area, 30-ft deep excavation.
  • New West Wing Addition for parking and central plant, situated in a small site immediately adjacent to the existing hospital, parking garage, and walkway.
  • Extensive re-entrant corner conditions requiring splayed nails. Existing hospital and walkway foundations needed to be supported.
  • Soil conditions consisted of 15-ft of loose fill underlain by dense glacial till.
  • New heavy footing surcharge loads on the order of 400 kips each, dead plus live load, at various locations immediately behind the shoring walls.
  • Large column loads, transverse floor slab moments, and in-plane seismic shear wall loads transferred to the top of the soil nail shoring walls throughout the perimeter of the walls.
CONSIDERATIONS FOR SOIL NAIL SHORING WALL SELECTION AND DESIGN
  • Cut face instability associated with fill soils prohibited the use of a typical shotcrete soil nail wall system with staged lifts that have no cut face support.
  • The Owner's consultants initially concluded that the only other available shoring system was a relatively expensive anchored soldier pile system.
  • The design-build team proposed the use of small 8-inch diameter face piles, 15-ft long, installed on 3-ft centers around the excavation perimeter to pre-support the fill soils prior to soil nail construction. The enhanced soil nail wall system was much less expensive than a conventional soldier pile system.
  • The soil nail design was successfully adapted to the re-entrant corners, existing hospital and walkway foundations, new pin-piles, and existing ground anchor obstructions.

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Ground Support PLLC
2475 - 152nd Avenue NE
Redmond, WA  98052
  Phone: (425)376-0177
Fax: (425)376-0277
email: info@groundsupport.com
    
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updated 5/30/2000