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Published byRoman Catchpole Modified over 9 years ago
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Upper Ouachita National Wildlife Refuge GRS Abutments for Replacement Bridges Michael Adams- FHWA Scott A. Saunders – FHWA/ EFLHD
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Ouachita Bridge Replacement GRS Abutments l Introduction l BOF Program l Design and GRS Technology l Construction l Instrumentation l Performance/Conclusion
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Ouachita Bridge Replacement Introduction l Replace 3 bridges in National Wildlife Refuge l Alternative foundation and abutment design l Evaluate cost, constructability and performance
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Bridge of the Future l Develop new technologies to build better, more efficient bridge systems. l Cost-effective designs and efficient construction techniques for 70-90 foot bridge systems. l Improved durability, maintenance, inspection accessibility and long-term performance. l Meet the growing demand for bridge replacement projects.
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Upper Ouachita National Wildlife Refuge
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Bridge Sites
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Old Rail Car Bridges
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Site Conditions Bottomland Bayous
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Cecil Creek Subsurface Profile
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GRS Technology l What is it? (MSE vs. GRS) l Design l FHWA GRS Research l An alternative to driven pile foundations
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GRS Technology GRS Walls and Abutments l Built with readily available materials l Common construction equipment l Without highly skilled labor
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GRS Technology Current GRS Projects
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2 Factors for Internal Stability l Good compaction with quality fill l Close reinforcement spacing Bulging wall face indicates that the two factors were not practiced; It is not an excuse to use mechanical connection between blocks
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GRS Design l Bearing Capacity (check) l Direct Sliding/Global Stability (check) l Eccentricity l Strength (check) l Connection l Pullout
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Thrust on Facing Elements Assuming a “yielding” facing h h 7/10 S 3/10 S S Reinforcement Granular Backfill ( = 34°) ( lbs/ft 2 h = S K a = S tan 2 (45°- 34°/2) = 125 S (0.283) = 35.4 S F = h (7/10 S) + h (3/10 S) = 43/60 h S = 25.4 S 2 lbs/ft Wu, McMullen, and Ruckman
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Reinforcement Spacing Controls Performance
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Bridge Plan & Elevation
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GRS Abutment
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GRS Wrap Detail
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GRS Abutment Materials l Geotextile Woven Polypropylene Type VIIA Contech C400 Type VIIB Contech C300 Wide Width Tensile Strength 4800 lb/ft & 2100 lb/ft l Aggregate Backfill Arkansas DOT - Aggregate Base Course Class 7: 1½ Maximum grain size
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Abutment Construction
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Spread Footing on GRS Abutment Cut Off Creek
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Bridge Construction
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Elastomeric Bearing Pad
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Cutoff Creek Bridge
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Cecil Creek Bridge
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Big Lake No. 2 Bridge
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Borehole Instrumentation
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Instrumentation/Monitoring l Magnetic Extensometers l Inclinometer l Survey
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Instrumentation 1C2C Magnetic Extensometer
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Instrumentation 1A2A 2B 1B Inclinometer
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Inclinometer South Abutment
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Inclinometer North Abutment
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Settlement Data settlementangular distortion averagedifferential(differential/L) BridgeL= 67 ft Cecil Creek0.780.270.0003 1.05 Big Lake0.690.0330.00041 0.36 Cutoff Creek0.06 0.03 0.00004 AASHTO Criteria = 0.005
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Lab Testing l Comparison w/ field instrumentation results l Consolidation tests on Cecil Creek samples l South Abutment – Running Sands
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Conclusions GRS vs. Pile Foundations l Cost: 40 % less than pile foundations (w/o footings) l Savings using shorter beams l Easy to deliver site materials l Less equipment required l Simplified QA/QC program l Less time to construct
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Performance l Total settlement < 1.5 inches l Differential Settlement: 0.5 inches l No “bump” at the bridge/road interface l Continued Performance Monitoring
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