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Publication Number: FHWA-HRT-11-027
Date: JANUARY 2011

 

Electronic Distribution of Geosynthetic Reinforced Soil Integrated Bridge System Synthesis Report Memo

508 Captions

Figures

Figure 1. Illustration. Typical GRS-IBS cross section. This figure depicts a typical cross section of a Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS) showing the reinforced soil foundation (RSF) (encapsulated with geotextile), the abutment (with reinforcement spaced at less than or equal to 12 inches), the bearing bed reinforcement (with load shedding layers spaced at less than or equal to 6 inches), facing elements that are frictionally connected (top three courses pinned and grouted), the integrated approach (geotextile wrapped layers at beam ends form smooth road transition), and the beam seat, which is supported directly on the bearing bed. The interface between the bridge beam and the GRS approach is jointless. Scour protection (e.g., rip rap) is also shown for the case of a bridge crossing a waterway.

Figure 2. Photo. MSE inextensible reinforcement—steel strips. This photo shows inextensible reinforcement used in mechanically stabilized earth (MSE) walls. Two steel strips are being placed on top of granular fill with pins used to tie the reinforcement to the facing.

Figure 3. Photo. MSE inextensible reinforcement—wire mats. This photo shows inextensible reinforcement used in mechanically stabilized earth (MSE) walls. A wire mat is on top of granular fill behind a wall facing.

Figure 4. Photo. MSE extensible reinforcement (geogrid). This photo shows a top view of uniaxial geogrids rolled out perpendicular to a welded wire basket face on top of compacted sand. This is a type of extensible reinforcement used in mechanically stabilized earth (MSE) structures.

Figure 5. Illustration. Typical wrapped-face GRS structure. This illustration shows a typical wrapped-face geosynthetic reinforced soil (GRS) structure. The geosynthetic is wrapped at the face for each of the nine layers shown. The wrapped face extends approximately one-fourth the length of the layer shown.

Figure 6. Photo. Cut-away of GRS mass. This photo shows a cut-away of a geosynthetic reinforced soil (GRS) mass. There are five courses of concrete masonry unit (CMU) block with geotextile frictionally connected between the blocks. Granular fill is in between each layer of reinforcement. The right side of the GRS mass has the blocks removed to show the internal structure.

Figure 7. Graph. General comparison of surcharges on MSE and GRS structures. This graph shows the vertical stress of traffic loads, traditional mechanically stabilized earth (MSE) experimental limits, working loads for geosynthetic reinforced earth (GRS) abutments, and the capacity of GRS experiments. Traffic loads are less than 1 kips/ft2. Traditional MSE experimental limits and working loads for GRS abutments are both at 4 kips/ft2. The capacity of GRS experiments is at 26 kips/ft2.

Figure 8. Photo. Internally supported GRS structure. This photo shows a geosynthetic reinforced soil (GRS) mass beside a bridge approach embankment. The GRS mass does not have a facing, only layers of geotextile reinforcement and fill material. There are 24 layers. The reinforcement at the top of the mass extends beyond the edges and lays over the fill.

Figure 9. Illustration. Idealized lateral earth pressure at the face of a GRS structure. This illustration shows the lateral pressure distribution at the face of a geosynthetic reinforced earth (GRS) wall with height H. The pressure is zero at the surface, linearly increases to a point about one-seventh of the way down the wall, and is then uniform with depth.

Figure 10. Illustration. Bin pressure diagram for GRS structures. This illustration shows the bin pressure diagram for geosynthetic reinforced earth (GRS) structures. The bin pressure distribution is between the reinforcement layers with a spacing of S subscript v. The pressure at the top of the layer is at one-third times the maximum lateral bin pressure, which occurs at seven-tenths times S subscript v from the top of the layer. The pressure at the bottom of the layer is at two-thirds times the maximum lateral bin pressure. The distribution is curved. The resultant force from the lateral bin pressure is termed F subscript bin.

Figure 11. Graph. Performance test results for different materials. This graph shows four stress-strain curves for different materials. The y-axis shows vertical strain (as a percentage), and the x-axis shows vertical stress (in ksf). The four materials are as follows: (1) c = 0 psf, phi = 48.7 degrees, dmax = 0.5 inch, Tf = 4,800 lb/ft, Sv = 8 inches; (2) c = 580 psf, phi = 40 degrees, dmax = 1 inch, Tf = 2,400 lb/ft, Sv = 8 inches; (3) c = 1,450 psf, phi = 50 degrees, dmax = 1.3 inches, Tf = 4,800 lb/ft, Sv = 8 inches; and (4) c = 390 psf, phi = 52.7 degrees, dmax = 1.3 inches, Tf = 4,800 lb/ft, Sv = 8 inches. All four lines start at zero and slope upward.

Figure 12. Graph. Predictive capability of the soil-geosynthetic composite capacity equation. This graph shows the predictive capability of the soil-geosynthetic composite capacity equation. The y-axis shows calculated (in psf) and the x-axis shows measured (in psf). There are 16 data points shown around the black line representing calculated equals measured. Five data points are from GSCS (Wu et al. 2010). Six data points are from Elton and Patawaran (2005). Two data points are from Defiance County (Adams et al. 2007). Two data points are from NCHRP (Wu et al. 2006). One data point is from Vegas Mini Pier (Adams et al. 2002). Most of the data points cluster close to the line. The Elton and Patawaran data points appear closest, and the GSCS data points lie farther out.

Figure 13. Graph. Design envelope for vertical strain at 8-inch reinforcement spacing. This graph shows a stress-strain curve from a performance test used to predict the ultimate vertical capacity and strain. The y-axis shows vertical strain as a percent, and the x-axis shows applied vertical load (ksf). The line on the graph begins at 0 ksf applied load at 0 percent vertical strain and extends to about 26 ksf applied load at about 5 percent vertical strain.

Figure 14. Graph. Deformation estimation from in-service GRS-IBS structures. This graph shows data points from five in-service Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS) structures superimposed over the stress-strain curve from an applicable performance test. The y-axis shows vertical strain (as a percentage) and the x-axis shows applied vertical load (in ksf). The data points (from Huber, Vine, Bowman, Stever, and Glenburg Bridges) line up along the stress-strain curve.

Figure 15. Illustration. Lateral deformation of a GRS structure. This illustration shows the lateral deformation of a GRS abutment due to a surcharge, q. The lateral deformation is triangular with the maximum deformation (D subscript L) located at about one-third from the top of the abutment having a total height H. The distance from the back of the facing block to the farthest edge of the surcharge, q, is labeled "b subscript q, vol."

Figure 16. Graph. Predictive capability of the required reinforcement strength equation. This graph shows the predictive capability of the required reinforcement strength equation. The y axis shows calculated (in psf), and the x-axis shows measured (in psf). There are 16 data points shown around the black line representing calculated equals measured. Five data points are from GSCS (Wu et al. 2010). Six data points are from Elton and Patawaran (2005). Two data points are from Defiance County (Adams et al. 2007). Two data points are from NCHRP (Wu et al. 2006). One data point is from Vegas Mini Pier (Adams et al. 2002). The data points cluster around the line, with the Elton and Patawaran points aligning closely, and the NCHRP and GSCS points appearing farther out.

Figure 17. Photo. Vine Street Bridge. This photo shows the Vine Street Bridge, which is in a rural, partially wooded area. It crosses a small body of water.

Figure 18. Graph. Vine Street GRS-IBS settlement versus time. This graph shows the settlement versus time plot for the Vine Street Bridge. The y-axis shows distance (in feet), and the x-axis shows time (in days). There are data points up to 1,200 days. There are four sets of points: the north beam average (largest settlement at the end of monitoring), the north wall average (lowest settlement at the end of monitoring), the south beam average (second largest settlement at the end of monitoring), and the south wall average (third largest settlement at the end of monitoring). The highest set of points appears just after day 600.

Figure 19. Photo. Glenburg Road Bridge under flood conditions. This photo shows the Glenburg Road Bridge under flood conditions. The bridge is in a rural area and crosses a small body of water that has flooded part of the land surrounding it.

Figure 20. Graph. Glenburg Road GRS-IBS settlement versus time. This graph shows the settlement versus time plot for the Glenburg Road Bridge. The y-axis shows distance (in feet), and the x-axis shows time (in days). There are data points up to 1,300 days. There are four sets of points: the north beam average (largest settlement at the end of monitoring), the north wall average (third largest settlement at the end of monitoring), the south beam average (second largest settlement at the end of monitoring), and the south wall average (lowest settlement at the end of monitoring). The highest set of points appears just before day 800.

Figure 21. Photo. Huber Road Bridge. This photo shows the Huber Road Bridge, which is in a wooded area and crosses a small stream.

Figure 22. Graph. Huber Road GRS-IBS settlement versus time. This graph shows the settlement versus time plot for the Huber Road Bridge. The y-axis shows distance (in feet), and the x-axis shows time (in days). There are data points up to 900 days. There are four sets of points: the north beam average (lowest settlement at the end of monitoring), the north wall average (second largest settlement at the end of monitoring), the south beam average (largest settlement at the end of monitoring), and the south wall average (third largest settlement at the end of monitoring). The highest set of points appears to be at about day 700.

Figure 23. Photo. Bowman Road Bridge after 4.5 years. This photo shows the Bowman Road Bridge. The bridge is part of a narrow road with trees to one side and a dirt field to the other. The bridge crosses a small stream.

Figure 24. Graph. Bowman Road GRS-IBS settlement versus time. This graph shows the settlement versus time plot for the Bowman Road Bridge. The y-axis shows distance (in feet), and the x-axis shows time (in days). There are data points up to 600 days. There are four sets of points: the east beam average (second largest settlement), the west beam average (largest settlement), the east face average (lowest settlement), and the west face average (third largest settlement). The points do not show large variations across the graph.

Figure 25. Photo. Tiffin River Bridge. This photo shows the Tiffin River Bridge. The bridge is depicted in winter and spans a partially frozen river.

Figure 26. Graph. Tiffin River GRS-IBS settlement versus time. The graph shows the settlement versus time plot for the Tiffin River Bridge. The y-axis shows distance (in feet) and the x-axis shows time (in days). There are data points up to 550 days. There are four sets of points: the north footing (largest settlement), the north wall (third largest settlement), the south footing (second settlement), and the south wall (lowest settlement). The highest points are located near zero days, with another set of higher points just after 300 days.

Figure 27. Graph. Settlement versus log-time plot to predict creep settlement for the Bowman Road Bridge at 100 years. This graph shows the settlement versus time plot for the Bowman Road Bridge. The y-axis shows distance (in feet), and the x-axis shows time (in days) in log scale. The x-axis is extended out to 100,000 days. Lines are drawn through the four sets of points to see where they intersect with a vertical line drawn at 365,00 days (100 years). There are four sets of data points: the east beam average (second largest settlement), the west beam average (largest settlement), the east face average (lowest settlement), and the west face average (third largest settlement).

Figure 28. Photo. GRS-IBS tunnel at TFHRC. This photo shows the tunnel in the Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS) built at the Turner-Fairbank Highway Research Center (TFHRC). This photo shows a distance view of the entire abutment. The tunnel is underneath the steps leading up to the top of the abutment.

Figure 29. Photo. Close-up of GRS-IBS tunnel at TFHRC. This photo shows the tunnel in the geosynthetic reinforced soil integrated bridge system (GRS-IBS) built at the Turner-Fairbank Highway Research Center (TFHRC). This photo shows a close-up of the opening of the tunnel. The tunnel is underneath the steps leading up to the top of the abutment.

Figure 30. Graph. Settlement versus time for TFHRC tunnel. This graph shows the settlement versus time plot for the Turner-Fairbank Highway Research Center (TFHRC) tunnel. The y-axis shows distance (in feet), and the x-axis is time (in years). There are two sets of points: the abutment side (which has a reinforcement with a strength of 4,800 lb/ft) and the embankment side (which has a reinforcement with a strength of 4,800 lb/ft). The settlement for the abutment side is slightly more than the embankment side.

Figure 31. Graph. Settlement versus log-time to predict creep settlement for TFHRC tunnel at 100 years. This graph shows the settlement versus time plot for the Turner-Fairbank Highway Research Center (TFHRC) tunnel. The y-axis shows distance (in feet), and the x-axis shows time (in years) in log scale. The x-axis is extended out to 100 years. There are two sets of points: the abutment side (which has a reinforcement with a strength of 4,800 lb/ft) and the embankment side (which has a reinforcement with a strength of 4,800 lb/ft). Lines are drawn through the two sets of points to see what the settlement is at 100 years. The settlement for the abutment side is slightly more than the embankment side.

Figure 32. Photo. GRS abutment behind historic stone abutment. This photo shows a geosynthetic reinforced soil (GRS) abutment behind a historic stone abutment. There are mountains behind the abutment.

Figure 33. Photo. Concrete box bridge on GRS abutment in Mammoth Lake, CA. This photo shows a concrete box bridge on a geosynthetic reinforced soil (GRS) abutment in Mammoth Lake, CA. The bridge is near a dirt road in a mountainous area with trees.

Figure 34. Illustration. Cross section of GRS abutment behind historic stone abutment. This illustration shows a cross-section of a geosynthetic reinforced soil (GRS) abutment built behind an old stone abutment. Layers of reinforcement are located behind and up to about two-thirds the height of the old abutment. There are 13 layers. The top four layers have reinforcement of uniform length and are longer than the bottom layers that also have uniform length. A footing is on top of the layers up to the height of the old abutment. A concrete beam is shown on top of the footing and extends past the old abutment.

Figure 35. Photo. Concrete box bridge on GRS abutment in Ouachita wildlife refuge. This photo shows a concrete box bridge on geosynthetic reinforced soil (GRS) abutments in the Ouachita wildlife refuge. The bridge is under construction and stretches over a body of water in a wooded area.

Figure 36. Illustration. Cross section of GRS abutments in Ouachita wildlife refuge. This illustration shows a cross-sectional sketch of the geosynthetic reinforced soil (GRS) abutments in the Ouachita wildlife refuge. The bridge is supported on a spread footing that is underlain by five layers of geosynthetic reinforcement. Reinforcement is also located behind the spread footing (three layers) and the beam (three layers) as an integrated approach. Riprap revetment is shown along the embankment slope with the water level at the base of the slope. Riprap extends below this level.

Figure 37. Graph. Measured and calculated lateral deformation on the Tiffin River Bridge GRS abutment. This graph shows the measured and calculated lateral deformation for the Tiffin River Bridge. The y-axis shows lateral deformation (in feet), and the x-axis shows time (in days). The average midwall bulge curve is shown with the theoretical (calculated) bulge on top. Vertical error bars representing an error of ±0.005 ft are also shown from the average midwall bulge. The curves match well.

Figure 38. Illustration. Instrumentation for Tiffin River Bridge. This illustration shows the location of instrumentation on a cross section of the geosynthetic reinforced soil integrated bridge system (GRS-IBS) for the Tiffin River Bridge. There are vibrating wire earth pressure cells located along the middle of the back wall, in the middle of the bearing seat, and 6 ft directly below the bearing seat. The superstructure is 7 ft tall from the base of the concrete footing to the top of the steel girder. For the GRS abutment, the width of the reinforcement for the bottom 6 layers is 8.5 ft; the width of the next 10 layers is 11 ft, followed by reinforcement for 13 layers at 18 ft. The 11 layers of reinforcement for the integrated approach are 18 ft long. There is secondary geotextile reinforcement for the bearing reinforcement bed that terminates 6 ft below the bearing seat. It extends to the length of the base reinforcement. Secondary geotextile reinforcement is also located in the integrated approach and terminates at the same location as the bearing reinforcement bed. The reinforced soil foundation (RSF) and scour protection are also shown.

Figure 39. Photo. Pressure cells behind back wall on Tiffin River Bridge. This photo shows two earth pressure cells installed on the concrete back wall.

Figure 40. Graph. Average lateral pressure on back wall for Tiffin River Bridge. This graph shows the average lateral pressures on the north and south beam end, along with the measured temperature at each interval. There are two y-axes: the left shows lateral pressure (in psf) and the right shows temperature (in degrees Fahrenheit). The x-axis shows time (in months). The data is measured from 12/16/09 to 05/16/10. The lateral pressure generally follows the temperature profile.

Figure 41. Photo. TFHRC pier test. This photo shows the Turner-Fairbank Highway Research Center (TFHRC) pier test. The pier has a concrete platform on top with steel bars sticking out. A trailer is next to the pier.

Figure 42. Photo. Block pull-out test on GRS wall. This photo shows a block pull-out test on a geosynthetic reinforced soil (GRS) wall. A dial gauge, hydraulic rams, and a load cell are identified in the figure.

Figure 43. Illustration. Block pull-out test setup. This illustration shows front and top views of the geosynthetic reinforced soil (GRS) wall load test. The front view shows that the anchor for the pull-out test is located in the middle of a segmental retaining wall (SRW) block that is 18 inches wide. Additionally, 10-ton hydraulic rams are shown on each side of a 4.5-inch connector bar with hoses attached at their ends to connect to a pump. The top view shows that the SRW blocks are 12 inches thick. The anchor is embedded in the middle of a SRW block by 2.7 inches. The 10,000-lb load cell is located on the anchor, outside of the metal plate.

Figure 44. Graph. Pull-out test results for an SRW block seven rows from the top. This graph shows the pull-out test results for a segmental retaining wall (SRW) block that is seven rows down from the top. The y-axis shows average displacement (times 0.001 inches), and the x axis shows load (in pounds). There are eight data points. The displacement does not increase until 1,200 lb and then increases to almost 0.425 inches at 1,400 lb.

Figure 45. Graph. Pull-out test results for an SRW block 11 rows from the top. This graph shows the pull-out test results for a segmental retaining wall (SRW) block that is 11 rows down from the top. The y-axis shows average displacement (times 0.001 inches), and the x-axis shows load (in pounds). There are 11 data points. The displacement does not increase until about 1,800 lb and then increases to about 0.55 inch at 2,000 lb.

Figure 46. Graph. Pull-out test results in terms of normal force for SRW blocks. This graph shows the pull-out test results for each test for segmental retaining wall (SRW) blocks. The y axis shows frictional capacity (in pounds), and the x-axis shows normal force (in pounds). The normal force scale is from 0 to 1,200 lb the frictional capacity scale is from 0 to 4,000 lb. As the normal force increases, the frictional capacity increases.

 

Equations

Equation 1. T subscript req. T subscript req equals the difference of sigma subscript h and sigma subscript c times S subscript v divided by the quantity 0.7 raised to the power of the quotient one-sixth S subscript v and d subscript max.

Equation 2. F subscript bin. F subscript bin equals 0.72 times gamma times K subscript a times the square of S subscript v.

Equation 3. q subscript ult,an,c. q subscript ult,an,c equals the sum of the product of K subscript pr and the sum of sigma subscript c and the product of 0.7 raised to the quotient of one-sixth S subscript v and d subscript max and the quotient of T subscript f and S subscript v and the product of 2c and the square root of K subscript pr.

Equation 4. Sigma subscript c. Sigma subscript c equals gamma subscript fb times D subscript f times the tangent of delta.

Equation 5. Sigma subscript h difference. Sigma subscript h equals the difference of the product of sigma subscript v and K subscript and the product of 2c and the square root of K subscript a.

Equation 6. Sigma subscript h sum. Sigma subscript h equals the sum of sigma subscript c and delta sigma subscript 3.

Equation 7. Delta sigma subscript 3. Delta sigma subscript 3 equals the product of W and the quotient of T and S subscript v.

Equation 8. W. W equals 0.7 raised to the power of the quotient of one-sixth S subscript v and d subscript max.

Equation 9. q subscript ult,an. q subscript ult,an equals the product of K subscript pr and the product of 0.7 raised to the quotient of one-sixth S subscript v and d subscript max and the quotient of T subscript f and S subscript v.

Equation 10. Delta V subscript top. Delta V subscript top equals b subscript q,vol times L times D subscript v which equals Delta V subscript face which equals one half H times L times D subscript L.

Equation 11. D subscript L. D subscript L equals 2 times b subscript q,vol times D subscript v divided by H.

Equation 12. Epsilon subscript L. Epsilon subscript L equals the quotient of D subscript L and b subscript q,vol which equals the quotient of the product of 2 and D subscript v and H which equals the product of 2 and epsilon subscript v.

Equation 13. T subscript req,c. T subscript req,c equals the product of S subscript v and the quotient of the different of sigma subscript h, sigma subscript c, and the product of 2c and the square root of K subscript a and 0.7 raised to the power of the quotient of one-sixth S subscript v and d subscript max.

Equation 14. T subscript req. T subscript req equals the product of sigma subscript h and S subscript v divided by 0.7 raised to the power of the quotient of one-sixth S subscript v and d subscript max.

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