Numerical Study of Spudcan Penetration in Clay-Sand-Clay Soil

Abstract

Aiming at simulating the preloading process of jack-up rig at drilling locations with typical stratum combination near the Yellow River estuary, FE models of interaction between spudcan and sub-soil are set up based on a large deformation finite element method known as Remeshing and Interpolation Technique with Small Strain (RITSS). The ABAQUS finite element package is used to calculate small strain solutions following each step. The seabed can be simplified as a three-layer deposits with soft clay layer, sand layer and soft clay layer from surface to bottom according to geological data. The backfill phenomenon during preloading is described. The results show that the surface soft clay falls onto the upper surface of spudcan very soon after the preloading process begins, afterwards the backfill tendency occurs in the middle sand layer. SNAME recommends two sets of formulas for calculating penetration resistance respectively for backfill penetration and penetration with no backfill. In this study the model with no backfill is realized by condition control in program codes and the penetration resistance is compared with the results of practical backfill model. The variance proves the shortcomings of the method given by SNAME.

Predicting the overall horizontal bearing capacity of jack-up rigs using deck–foundation–soil-coupled model

“…18 The Young’s modulus of the sandy silt is E s = 30 MPa, and Poisson’s ratio is v s = 0.3. 19 The horizontal boundary of the soil model is 2.5 D away from the edge of the spudcan. The soil is meshed using C3D8R elements, which are defined as a three-dimensional, hexahedral eight-node linear brick element with reduced integration.…”