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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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Presentation on theme: "Upper Ouachita National Wildlife Refuge GRS Abutments for Replacement Bridges Michael Adams- FHWA Scott A. Saunders – FHWA/ EFLHD."— Presentation transcript:

1 Upper Ouachita National Wildlife Refuge GRS Abutments for Replacement Bridges Michael Adams- FHWA Scott A. Saunders – FHWA/ EFLHD

2 Ouachita Bridge Replacement GRS Abutments l Introduction l BOF Program l Design and GRS Technology l Construction l Instrumentation l Performance/Conclusion

3 Ouachita Bridge Replacement Introduction l Replace 3 bridges in National Wildlife Refuge l Alternative foundation and abutment design l Evaluate cost, constructability and performance

4 Bridge of the Future l Develop new technologies to build better, more efficient bridge systems. l Cost-effective designs and efficient construction techniques for foot bridge systems. l Improved durability, maintenance, inspection accessibility and long-term performance. l Meet the growing demand for bridge replacement projects.

5 Upper Ouachita National Wildlife Refuge

6 Bridge Sites

7 Old Rail Car Bridges

8 Site Conditions Bottomland Bayous

9 Cecil Creek Subsurface Profile

10 GRS Technology l What is it? (MSE vs. GRS) l Design l FHWA GRS Research l An alternative to driven pile foundations

11 GRS Technology GRS Walls and Abutments l Built with readily available materials l Common construction equipment l Without highly skilled labor

12 GRS Technology Current GRS Projects

13 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

14 GRS Design l Bearing Capacity (check) l Direct Sliding/Global Stability (check) l Eccentricity l Strength (check) l Connection l Pullout

15 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

16 Reinforcement Spacing Controls Performance

17 Bridge Plan & Elevation

18 GRS Abutment

19 GRS Wrap Detail

20 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

21 Abutment Construction

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27 Spread Footing on GRS Abutment Cut Off Creek

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33 Bridge Construction

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35 Elastomeric Bearing Pad

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38 Cutoff Creek Bridge

39 Cecil Creek Bridge

40 Big Lake No. 2 Bridge

41 Borehole Instrumentation

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44 Instrumentation/Monitoring l Magnetic Extensometers l Inclinometer l Survey

45 Instrumentation 1C2C Magnetic Extensometer

46 Instrumentation 1A2A 2B 1B Inclinometer

47 Inclinometer South Abutment

48 Inclinometer North Abutment

49 Settlement Data settlementangular distortion averagedifferential(differential/L) BridgeL= 67 ft Cecil Creek Big Lake Cutoff Creek AASHTO Criteria = 0.005

50 Lab Testing l Comparison w/ field instrumentation results l Consolidation tests on Cecil Creek samples l South Abutment – Running Sands

51 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

52 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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