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 70-90 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

27. Spread Footing on GRS Abutment Cut Off Creek

33. Bridge Construction

35. Elastomeric Bearing Pad

38. Cutoff Creek Bridge

39. Cecil Creek Bridge

40. Big Lake No. 2 Bridge

41. Borehole Instrumentation

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 Creek0.780.270.0003 1.05 Big Lake0.690.0330.00041 0.36 Cutoff Creek0.06 0.03 0.00004 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