Shaft resistance of piles in lateritic soils: a reevaluation based on Brazilian experience

Lateritic soils are widely distributed in tropical regions and are characterized by a cemented structure due to iron and aluminum oxides. Although the Standard Penetration Test (SPT) is commonly used in Brazil, it does not adequately capture the stiffness of these cemented layers, leading to overly conservative pile design and increased costs. To address this limitation, this study presents a reevaluation based on 43 pile load tests in lateritic soils across various Brazilian sites. Results confirm that the traditional method by Décourt & Quaresma (1978), as later adapted by Décourt (1996), underestimates shaft resistance, with measured values averaging 2.1 times higher. This study proposes an adjustment methodology introducing a correction factor for lateritic soils (β = 2), which produced satisfactory predictions in 76.75% of cases, with 39.5% within a ± 20% margin. However, 23.25% of cases exceeded this range, mainly for manually excavated small-diameter piles, indicating sensitivity to construction methods and the need for site-specific calibration.