Compacted Soil-Cement Treatment for Collapsible Soils Adjacent to Laterally Top-Loaded Flexible CFA Piles

Lateritic soil usually features an apparently strong structure that can disintegrate upon contact with water and loads. This condition, coupled with high porosity, characterizes the soil in the Campinas region, Brazil. This study investigates the impact of soil–cement treatment on this soil type when adjacent to flexible Continuous Flight auger (CFA) piles (L/D=30), under both natural and flooded conditions. Four piles were installed, and 10 lateral load tests were conducted covering untreated nonflooded, untreated flooded, treated nonflooded, and treated flooded conditions. Additional analyses were conducted based on a previously published case of this soil treatment with full-displacement piles—FDP (Omega type) performed in the same experimental field. Results showed that soil treatment increased load capacities and horizontal reaction coefficients (nh), and reduced losses under saturated conditions. CFA piles exhibited greater increases in load capacities and nh under nonflooded conditions, whereas FDP piles experienced lower nh losses under saturation. Comparison with other pile types tested at the site revealed that achieved load and nh remained relatively high even under flooding, despite significant percentage reductions.