Throwback Thursday: Soil Nail Shoring System – Canyon Crossing Center

Canyon

The Canyon Crossing project is located in Frederickson,

WA, a rapidly growing suburb of the town of Tacoma, south

of Seattle. The project site is approximately 592,000 ft² and

will include the construction of a supermarket; six out-parcel

buildings and a fueling center. The topography of the site

prohibited a project of this size from being constructed

without a vertical shoring system. A permanent soil nail

shotcrete shoring system was selected to stabilize and

tieback the east and south sides of the project site. The

site conditions required the average height of the soil nail

wall to be 45 feet.

The eastern slope of the project site was stabilized with

approximately 709 EA – epoxy coated soil nails and

southern slope was stabilized with approximately 543 EA

- galvanized soil nails. The average drill depth of the soil

nails was 30 feet. The difficult ground conditions required

the soil nails to be drilled using “Rotary Percussive Duplex”

drilling techniques in order to advance the inner drill steel

and casing simultaneously.

The two retaining walls have a surface area of approximately

26,000 ft². The construction procedure started with the

installation and grouting of the soil nails. After each row

of soil nails was installed and grouted, a 4-inch thick

temporary shotcrete facing was placed in 6-foot vertical lifts.

The final step of the construction sequence was to place

an 8-inch thick permanent shotcrete face over the entire

wall surface. The permanent facing was then architecturally

carved and textured to resemble natural granite stone.

Numerous shoring system options were explored during the

preliminary phases of the project. The most feasible and

economical solution due to the erratic nature of the subsurface

conditions throughout the project site was determined to be a

soil nail / shotcrete system. The versatility of this shoring system

also offered the owner an option to architecturally carve the

shotcrete facing to provide future tenants of the property with

an appealing natural looking rock wall versus an unattractive

grey concrete wall.

The project was an overall success. We were able to reshape the landscape

of the area and provided a new landmark to the neighborhood.


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