Abstract

VALLE-MOLINA, Celestino et al. Numerical evaluation of the combined capacity of suction caissons of subsea systems for deep water hydrocarbon exploitation. Ing. invest. y tecnol. [online]. 2019, vol.20, n.1. ISSN 2594-0732.  https://doi.org/10.22201/fi.25940732e.2019.20n1.004.

Suction caissons are used to fix submarine systems of production into the seafloor for exploding hydrocarbons. The foundations of submarine systems are subjected to combined or multiaxial loading, which consists in applying combinations of horizontal and vertical loading (H,V) with driving moments (M). The main objective of this research work was to estimate numerically the combined capacity by means of failure envelopes of a suction pile installed in normally consolidated soil and subjected to combined loading applied at the head. The failure envelope represents the boundary of the combination of loading that the pile-soil can withstand. Finite element program ANSYS® 14.5 was used to model the caisson-soil system and evaluate the capacity of the caissons subjected to 17 combinations of HM failure loading and 22 linked values of VM maximum loading. Each numerical result permit to conform failure surfaces, which for the HM capacity exhibit rotated elliptical shapes with clear symmetry, while failure envelopes of the MV plane exhibit thong-shape failure and are clearly non-symmetrical. In this research, the pure compressional capacity was 72% higher than the pure extensional capacity. The mechanisms of failure of the caissons loaded at the head meet very well with the modes reported in the oil industry. Caissons subjected to horizontal loading in positive convention (applied from left to right direction) and clockwise moment exhibited “external-scoop” mechanisms, while caisson under positive lateral loading and counter-clockwise moments might experience translational or rotational failure mechanisms. Finally, this research work permits to quantify the impact of the variation of the mechanical properties of the soil on the caisson capacity as well as the type and size of the failure modes of the foundation.

Keywords : Suction caissons; subsea production systems; deep water.

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