B212 Bremerhaven, renovation of the eastern road embankment to the Geestebrücke bridge GERMANY – 2000
Bridges and Walls (03-003-A)
03-003-A – pag 2/4
Problem Since the bridge was completed in 1994, traffic load has caused serious settlement in the embankment; High maintenance cost due to repeated asphalting of the contact area with the bridge to level the surface (to over 1 m), without any signs of the settlement coming to an end.
Cubic Area: 4,500 m3. Load: ADT = 26,000 vehicles/day; ADTT = 1,000 vehicles/day.
Additional applications of asphalt wearing courses led to additional settlement
Composition Road bed 4 cm stone mastic asphalt; 6 cm asphalt binder 0/16; 18 cm base course, CS sand mix; 23 cm ballast base course (0/45) made from natural stone slight extra height given to the renovated section. Base 30 cm recycled concrete on a covered expanded clay fill; geotextile GRK 4 as a separating course; 8-16 mm Leca® (370 kg/m3), thickness running from 4 m down to 0.5 m (over a length of 80 m), wrapped in GRK 4 geotextile; Side support packing, made of sand, 80 cm thick;
1. Removal of the road bed and the old embankment fill down to the original terrain; 2. Application of the side support slope at a gradient of around 60º up to about 1/4 - 1/3 of the final fill height; 3. Positioning of the geotextile on the road bed; 4. Application of the Leca® 8-16 mm, spreading and compaction using a light bulldozer in layers of approx. 1 m; 5. Application of the Leca® 8-16 mm in the area of the bridge abutment and the drainage channels in layers of 50 cm + compaction with a light vibroplate; 6. Construction of the side slopes with a gradient of 1:1.5, and pouring of the support packing + compaction with medium vibroplate; 7. Application of the Leca® 8-16 mm to height and covering with textile; 8. Application of the recycled concrete layer by frontal unloading and compaction with a dynamic 6-tonne roller (4-6 passes); 9. Conventional construction of the road surface.
Subsoil Embankment fill made from uniform, densely packed fill sands; Large site at AOD +2.5 m; 15-18 m clay, argillaceous, very silty, organic, with enclosed peat seams.
Construction Core filling of the approach embankment over a length of 80 m. Geeste Swing Bridge
Fixed Bridge Section (East)
Section for Renovation
Leca® application 80 m
03-003-A – pag 3/4
Longitudinal Difference Measurements (North) Deformation (m)
Construction of the section, fully closed to traffic. Duration: 3 weeks.
Distance from abutment (m)
Construction of the side support embankments
Slope of the expanded clay fill, gradient 1:1.5
Longitudinal Difference Measurements (Centre)
Distance from abutment (m) Longitudinal Difference Measurements (South)
Plate-bearing tests On the road bed plate ø300 mm at 4m fill: Ev2 ~ 105 MN/m2 Ev2/Ev1 ~ 1.8 at 2m fill: Ev2 ~ 75 MN/m2 Ev2/Ev1 ~ 2.6 On expanded clay dynamic plate-bearing pressure test: Evd = 9-12 MN/m2 plate ø600 mm: Ev2 = 25-35 MN/m2 Ev2/Ev1 = 2.5-3.2 On recycled concrete layer: plate ø300 mm on 4m of ex. clay: Ev2 ~ 90 MN/m2 Ev2/Ev1 ~ 2 on 1m of ex. clay: Ev2 ~ 120 MN/m2 Ev2/Ev1 ~ 1.6 required: Ev2 ~ 80 MN/m2 Ev2/Ev1 ~ 2.5 On crushed stone base course plate ø300 mm on 4m of ex. clay: Ev2 ~ 150 MN/m2 Ev2/Ev1 ~ 1.7 on 1m of ex. clay: Ev2 ~ 160 MN/m2 Ev2/Ev1 ~ 2.4 required: Ev2 ~ 120 MN/m2 Ev2/Ev1 ~ 2.5
Performance Measurements Settlement measurements in grid formation: max settlement after 1.5 years ~2 cm; area with most settlement 10-40 m behind the bridge abutment.
Distance from abutment (m) after 3 months after 6 months after 9 months after 12 months after 15 months after 18 months
Inclinometer measurements (vertically through the embankment shoulder): No deformations detected.
Inclinometer tubes before use
Hydrostatic measurement, beneath and on the expanded clay layer, under the bituminously bound base course: distressing under the expanded clay layer; slight bulge = settlements reduced. Flaws/damage Type: none. Time: --
03-003-A – pag 4/4
Visual appraisal as of 08.07.2004 Deformations: lengthways/crossways: impeccable condition; Transitional/contact areas: impeccable condition; Road surface: no visible flaws.
View of the approach embankment – no detectable flaws
Maintenance work Normal.
Appraisal/Experiences Application of Leca® possible using standard earth-moving equipment; Roadbuilding requirements can be satisfied; Heavier settlement in the area close to the bridge abutment: due to greater surface pressure, or due to grain movement in the thicker Leca® layer? Connection between thickness and internal settlement of the Leca® ? Little settlement directly next to the bridge abutment due to its construction using a transition slab and support from the bridge abutment; Standard quality control methods applicable.
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