Pile Behavior Due to Adjacent Jack-up Spudcan Penetration

The large soil movement induced by the installation of mobile jack-up spudcan footing could affect the pile foundation supporting the adjacent permanent jacket platform. This study performs standard gravity (1g) model tests to investigate the induced bending moment on a single pile due to spudcan penetration in uniform clay and sand-over-clay profiles. The thickness of the upper sand layer, clearance between the pile and the spudcan edge, and pile head conditions are among the variables examined. The results revealed that a fixed headed pile experienced negative bending moments at the pile cap and upper pile shaft, and positive bending moments along the lower pile shaft. The magnitude of induced pile moment reduced with increasing spudcan-pile distance. In sand overlying clay, spudcan punch-through hazard resulted in greater induced pile bending moment as compared to that in single clay. A free head pile experienced smaller negative moments at shallow spudcan penetration depths owing to the unrestrained pile head. When the spudcan advanced deeper, the induced pile moment shifted to the positive magnitude at the midpile shaft, revealing the turning point of soil pressures acting on the pile. In single clay, the maximum positive pile moment gradually increased with increasing spudcan penetration depth. In sand over clay, the maximum positive pile moment peaked at the spudcan penetration depth of three-quarters of the spudcan diameter and then decreased drastically beneath this spudcan penetration depth. Despite the limitation of 1g tests not being capable of replicating prototype soil stresses, the present study still can establish crucial information on pile behavior due to spudcan penetration.