Pile-boulder resistance relationship for pile tip buckling during impact driving

1. Home
2. Publications
3. Online Library
4. Pile-boulder resistance relationship for pile tip buckling during impact driving

The presence of buried boulders can be a critical aspect during installation of impact driven open-ended tubular piles. A pile-boulder contact implies that for each hammer blow the boulder will be pushed down and away from the pile, or the pile tip may buckle, or both, which can lead to installation problems and even refusal.

To model the reaction force of the boulder on the pile, a one-dimensional visco-elastic plastic model approach is proposed, which is based on the dynamic response of the pile end bearing proposed by Simons and Randolph (1985), including the lumped boulder mass in the pile-boulder response. The reaction force is presented in terms of the boulder displacement, i.e. as a non-linear spring which accounts for the impact point, the boulder size and mass, the properties of the embedded soil, and the characteristics of the travelling force wave in the pile.

A 2D axisymmetric finite element model was developed in Abaqus to confirm the proposed model for the boulder response during a single blow, when the boulder is impacted vertically by the pile along its vertical axis, performing non-linear transient dynamic analyses. Assuming homogeneous, isotropic soil behaviour and considering the boulder sufficiently deep, its response will be the same in any direction and therefore 3D modelling is not needed. To calibrate the associated correction factors for the 1D formulation, sensitivity studies were performed varying the boulder size and the soil strength and stiffness.

5th International Symposium on Frontiers in Offshore Geotechnics (ISFOG2025)

7 - Pile design and installation in challenging soil conditions: glauconite, carbonated soils, cemented soils, gravels and rocks