Tram Line 6, Bremen Huchting-Grolland GERMANY – 1997
Railways (02-002-A)
02-002-A– pag 2/3
Problem Serious settlement in the affected stretch of track, embankment approx. 1.5 m high, constant maintenance work required.
Cubic Area: 3,300 m3 over a length of 300 m. Load: ADT = 20,000 vehicles/day; ADTT = 1,600 vehicles/day.
Composition Track bed 20-25 cm track ballast; Track and sleepers laid on the ballast bed.
On track ballast (600 plate): Ev2 = 109 MN/m2; Ev1 = 64.7 MN/m2; Ev2/Ev1 = 1.7.
Base Replacement of the sand fill with Leca®, d = 1 m; Wrapped in geotextile; 30 cm aggregate mixture.
Measurement of particle size curve Expanded clay: before application (uncrushed) – U = 1.5. After application – U = 56-70. Track ballast: 20-60 mm – U = 1.5 very uniform shape.
Subsoil Ochtum River flood plain; 1.5-3 m sand fill; Below, clay soil in thicknesses of 1.7 to 5 m (some peat); Groundwater to 0.7m under grade, partially in the existing track bed. Water content Clay 30-110%; Peat 150-200%. Volatile solids Clay 5-25%; Peat 25-50%. Construction See Building method.
Compression check In applied state: ρd = 0.32 – 0.38 t/m3; Proctor density: ρd = ~0.5 t/m3.
Performance Measurements No data. Flaws/damage Type: none. Time: --
Building method 1. Removal of the track structure; 2. Partial replacement of the sand fill with Leca®; 3. Positioning of the geotextile beneath the track bed; 4. Application of Leca®, spreading and compaction using a light bulldozer in layers of approx. 1 m; 5. Wrapping in geotextile; 6. Application of the aggregate mix by frontal unloading; 7. Compaction of the aggregate mix; 8. Construction of the track bed surface.
Quality control Plate-bearing tests On Leca® with 300 plate: excessive settlement. On aggregate mix (300 plate): Ev2 = 64-96 MN/m2. On average: Ev2 = ~78 MN/m2; Ev1 = ~30 MN/m2; Ev2/Ev1 = ~2.6. Required: Ev2 = 80 MN/m2; Ev2/Ev1= 3.0.
Appraisal as of 07.07.2004 Track stretch in impeccable condition, no detectable deformations in the surface structure.
construction is
02-002-A – pag 3/3
Maintenance work Normal.
Appraisal/ Experiences Use of Leca® in track building has functioned well; Significant change in the particle size curve of the Leca® (grain crushing) during application/compression.
www.maxit-group.com maxitGroup AB, Box 415, SE-191 24 Sollentuna, Sweden Tel.: +46 (0)8 858 70 64 00, E-mail: info@maxit-group.com
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