Driven pipe piles are used extensively in coastal and offshore projects. Traditionally piles with diameters of 2–3 m were common in the offshore wind industry, however the diameter of monopiles to support a 10 MW wind turbine is more commonly 10 m. Offshore wind projects are being developed at sites with very low seabed strengths and pipe pile weights are increasing significantly. Self-weight penetration occurs when the pile is first placed on the seabed. A combination of low strength seabed conditions and increased pile self-weight leads to the risk of pile run (uncontrolled self-weight penetration) during installation at some sites. Predicting pile run risk, run velocities and penetration depths is challenging due to inherent rate effects and the large strains involved. While rapid penetration processes can be considered using both analytic methods and Large Deformation Finite Element simulations, the role of soil rigidity is seldom taken into account, despite known implications from static pile assessments. This study uses large deformation simulation with the Coupled Eulerian Lagrangian method to simulate the pile running process for five well-studied fine-grained soils with varying elastic stiffnesses. Results are compared with analytic methods, highlighting the limitations of current predictive techniques in terms of both the end tip and shaft resistance. As a corollary, a linear trend for the final penetration depth with respect to the logarithm of the soil rigidity index is incorporated in an existing analytic code based on results obtained from large deformation simulations.

Accurate determination of the load-penetration behaviour of spudcan footings is vital in predicting the performance of offshore structures. Often, insufficient site investigation data is a limiting factor in assessing spudcan penetration, with the selection of suitable parameters typically derived from triaxial tests or Cone Penetrometer Test (CPT) data. A method is presented for simulating spudcan insertion in loose to medium-dense sand, based on minimal data, whereby the CPT tip resistance is used in combination with known correlations of soil properties, allowing for back analysis of CPT profiles through Large Deformation Finite Element (LDFE) simulation. The use of LDFE allows for failure mechanisms to be determined a priori, as a result of the simulation process, while a range of constitutive models can be implemented as necessary. Friction angle, dilation angle and relative density correlations are combined with a calibration of the elastic modulus, used to develop numerical models based on a set of soil sub-layers, each 1 m in depth. The resulting soil characterisations were used to calculate the load-penetration behaviour of several spudcan geometries (which deviate from conventional spudcan shapes) using the LDFE, to assess their performance. Results generated using the proposed technique show strong agreement with a presented field observations.

Offshore jack-up rigs are most commonly founded on large-diameter conical “spudcan” foundations, which are frequently designed using traditional analytical methods for shallow footings. This paper presents the design of a spudcan installed off the coast of Tunisia. The maximum penetration depth of the footing under the available preload is predicted by a combination of analytical techniques, 2-dimensional axisymmetric modelling and 3-dimensional Finite Element Methods (FEM) using large strain arbitrary Lagrangian-Eulerian (ALE) techniques. Spudcan penetration based on FEM simulation of CPT soil profiles forms the basis of a comparison with results from the Society of Naval Architects and Marine Engineers (SNAME) guidelines. Particular attention is given to model calibration using the limited site investigation data available. Results are presented for the effect of penetrating footings on the behaviour of neighbouring footings, showing good agreement with conventional prediction methods.