This paper presents a case history of structural damage due to lateral soil movement and an analysis of stress and deformation in the supporting piles. The project involved cast-in-place concrete piles cased in steel pipes having 40.6-cm (16-in.) outside diameter and 38.7-cm (15¼-in.) inside diameter. The piles extended through a 7.6-m (25-ft) oyster shell fill and a 17-m (55-ft) soft clay layer and penetrated 7.6 m (25 ft) into a compact sand stratum. Due to overloading at the top of the fill, the soil surrounding the piles underwent lateral movement and caused cracking in the pile caps.
The amount of lateral soil movement was measured using inclinometers. Based upon the measured soil deformation, lateral soil pressures were determined with appropriate moduli of subgrade reaction. The soil pressures were used as lateral loading on a single pile. Using a finite element computer program that was developed based upon the theory of beam on elastic foundation, the deformation of the single pile and the horizontal reaction and resisting moment mobilized in the pile cap were analyzed. By comparing the horizontal reaction and resisting moment with the structurally determined ultimate values, the results of the pile behavior analysis were checked favorably.