Ground Stabilization using Deep Soil Mixing Technique for an Approach Ramp-PPT Presentation

PPT Presentation

Pdf Summary

The project stabilized an approach-ramp embankment using deep soil mixing (DSM) columns and a geosynthetic-reinforced load transfer platform (LTP). Ground conditions included soft-to-firm cohesive made ground over stiff boulder clay. The design aimed to limit future settlement to less than 20 mm, with no more than 10 mm after track installation, over a 120-year design life.<br /><br />Designed in accordance with the FHWA deep-mixing manual, the solution used 2 m diameter DSM columns with a target 90-day unconfined compressive strength (UCS) of 750 kPa. Column spacing and area replacement ratios varied by zone to accommodate different loads, soil conditions, and utility exclusion areas. The LTP comprised a 500 mm retained platform layer reinforced with two layers of 40/40 biaxial geogrid.<br /><br />The binder blend contained 30% ordinary Portland cement and 70% ground-granulated blast-furnace slag, at 206 kg per cubic metre of soil. Columns were installed in a single phase to depths of up to 11.5 m, with most slurry delivered during penetration and the remainder during extraction. Trial columns were used to calibrate installation and verify performance.<br /><br />A zone load test applied 250 kPa (1,500 kN) for one week. Measured settlement was 16 mm, within the specified 20 mm limit. Fresh-column samples were collected regularly and tested by an external laboratory at 28 and 90 days.<br /><br />The presentation concludes that DSM combined with the reinforced LTP met the project’s performance requirements and provided a cost-effective alternative to a piled foundation, saving time, money, and resources while supporting delivery ahead of schedule.

Keywords

deep soil mixing

DSM columns

geosynthetic-reinforced load transfer platform

embankment stabilization

approach-ramp settlement

soft cohesive made ground

boulder clay

unconfined compressive strength

biaxial geogrid

piled foundation alternative