October 8, 2008 Spokane, WA Doug Walters, P.E. King County DOT Sunday Creek Bridge Replacement Utilizing Geosynthetic Reinforced Soil (GRS) Abutments October 8, 2008 Spokane, WA Doug Walters, P.E. King County DOT
Project Location
Existing Log Stringer Bridge
Bridge Deck
Typical Bridge Traffic Prior to Load Restrictions
Deficiencies Structural Environmental Timber cribbing abutments & log stringers damaged Minor scour 1997- Placed temporary shoring load limit of 3 tons Environmental Cited by the WA Department of Fish and Wildlife Temporary shoring within stream channel
West abutment temporary shoring I-Beam on Ecology Blocks
East Abutment Temporary Shoring Shoring Support
Typical rot on log stringers
Superstructure: Prefabricated Steel Truss
Superstructure Selection Hydraulic Opening Above 100 year flood elevation Changing road grade additional environmental permitting Narrow Haul Road
Superstructure: Prefabricated Steel Truss 3ft clear space 12
Foundation Considerations Borings Alternating layers of medium dense alluvial gravel, sand, and silt Abutment Foundation Shallow foundation Base of foundation below stream’s thalwag elevation Sheet Pile Cutoff Walls Allow dry construction Provide additional scour protection
GRS Abutment Selection Constructability Avoid long concrete haul Not weather dependent Reduced time of construction Cost Savings Materials General labor Standard equipment Environmental No concrete placement
GRS Abutment Design Outline King County preliminary GRS abutment NCHRP Report 556 “Design and construction of GRS abutments” Mike Adams (FHWA) reviewed & refined design Provided GRS design detail with layout continue to provide evaluation, design, and construction support
BRIDGE LAYOUT 22 ft 104 ft PLAN 14 ft 25 ft
GRS ABUTMENT DETAIL FINISHED GRADE LINE
CMU Block Schedule 36 ft 23 ft 5 ft 9 ft 11 ft 11 ft
Tasks to be completed Finalize Design Bid January 2009 Construction June 2009
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