Application of Diverse Ground Improvement Techniques for the Stabilization of Reinforced Earth Wall Approach Ramps-Video

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A ground-improvement project was undertaken for the approach embankments to a tall U-turn structure, where strict settlement limits were needed to prevent differential movement near piled sections. Although the sand and gravel was dense, plate-load tests indicated potential collapse when inundated. The contractor proposed dynamic compaction, but the client selected a combination of methods: soil-mixing columns in the most heavily loaded zones, wet top-feed stone columns and vibro-compaction in other areas, followed by rapid-impact compaction.<br /><br />Water injected during treatment drained far more slowly than expected, and no significant collapse occurred. Dense ground also required pre-drilling for the stone columns. Two zone-load tests settled only 6–7 mm, below the 12.5 mm limit. Soil-mix samples exceeded the 1.5 MPa target strength on average, though some verification tests had to be replaced with density testing. Work finished ahead of schedule; long-term settlement results were not yet available because construction had not begun.

Keywords

ground improvement

settlement control

soil mixing columns

stone columns

vibro-compaction