# Presentation: 027090

## Upper Ouachita National Wildlife RefugeGRS Abutments for Replacement Bridges   

- Michael Adams- FHWA
- Scott A. Saunders – FHWA/ EFLHD

## Ouachita Bridge ReplacementGRS Abutments

- Introduction
- BOF Program
- Design and GRS Technology
- Construction
- Instrumentation
- Performance/Conclusion

## Ouachita Bridge Replacement

- Introduction
- Replace 3 bridges in National Wildlife Refuge
- Alternative foundation and abutment design
- Evaluate cost, constructability and performance

## Bridge of the Future

- Develop new technologies to build better, more efficient bridge systems.
- Cost-effective designs and efficient construction techniques for 70-90 foot bridge systems.
- Improved durability, maintenance, inspection accessibility and long-term performance.
- Meet the growing demand for bridge replacement projects.

## Upper Ouachita National Wildlife Refuge 

## Bridge Sites

## Old Rail Car Bridges 

## Site Conditions Bottomland Bayous

## Cecil Creek Subsurface Profile

## GRS Technology

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

## GRS Technology

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

## GRS Technology

- Current GRS Projects

## 2 Factors for Internal Stability

- Good compaction with quality fill
- 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

## GRS Design

- Bearing Capacity (check)
- Direct Sliding/Global Stability  (check)
- Eccentricity
- Strength  (check)
- Connection
- Pullout

## Thrust on Facing ElementsAssuming a “yielding” facing

- h

- h

- 7/10 S

- 3/10 S

- S

- Reinforcement

- Granular Backfill
-   (****= 34°)
-    (lbs/ft2

- h =  S Ka =  S tan2 (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 S2  lbs/ft

- Wu,  McMullen, and Ruckman

## Reinforcement Spacing  Controls Performance 

## Bridge Plan & Elevation

- Bridge Plan & Elevation

## GRS Abutment

## GRS Wrap Detail

## GRS Abutment Materials

- Geotextile
- Woven Polypropylene
- Type VIIA Contech C400
- Type VIIB Contech C300
- Wide Width Tensile Strength 4800 lb/ft & 2100 lb/ft
- Aggregate Backfill
- Arkansas DOT - Aggregate Base Course
- Class 7:  11⁄2  Maximum grain size

## Abutment Construction

## Slide 23

## Abutment Construction

## Slide 25

## Abutment Construction

## Spread Footing on GRS Abutment Cut Off Creek

## Slide 28

## Slide 29

## Slide 30

## Slide 31

## Slide 32

## Bridge Construction

## Bridge Construction

## Elastomeric Bearing Pad 

## Slide 36

## Slide 37

## Cutoff Creek Bridge

## Cecil Creek Bridge

## Big Lake No. 2 Bridge

## Borehole Instrumentation

## Slide 42

## Slide 43

## Instrumentation/Monitoring

- Magnetic Extensometers
- Inclinometer
- Survey

## Instrumentation

**1C**

**2C**

- Magnetic Extensometer

## Instrumentation

**1A**

**2A**

**2B**

**1B**

- Inclinometer

## Inclinometer

- South Abutment

## Inclinometer

- North Abutment

## Settlement Data

- settlement

- angular distortion

- average

- differential

- (differential/L)

- Bridge

- L= 67 ft

- Cecil Creek

- 0.78

- 0.27

- 0.0003

- 1.05

- Big Lake

- 0.69

- 0.033

- 0.00041

- 0.36

- Cutoff Creek

- 0.06

- 0.03

- 0.03

- 0.00004

- AASHTO Criteria = 0.005

## Lab Testing

- Comparison w/ field instrumentation results
- Consolidation tests on Cecil Creek samples
- South Abutment – Running Sands

## Conclusions

- GRS vs. Pile Foundations
- Cost: 40 % less than pile foundations (w/o footings)
- Savings using shorter beams
- Easy to deliver site materials
- Less equipment required
- Simplified QA/QC program
- Less time to construct

## Performance

- Total settlement < 1.5 inches
- Differential Settlement: 0.5 inches
- No “bump” at the bridge/road interface
- Continued Performance Monitoring