چكيده به لاتين
Today, different kinds of offshore drilling units “Jack-ups” are used for extracting petroleum in oil industry, which may be moved to another site when ending their mission. This research studies the jack-ups located on individual foundations (Spudcans). These rigs are used in more than half of the offshore oil and gas extraction projects. In this study, analysis is performed using finite element method and ABAQUS software. First, a model was validated with the installation data of the Oriental Platform 1 in the Ilam oil field 2 in the Persian Gulf and another model was validated using the data of a Spudcan penetrated in a two layered soil, a soft clay layer under a hard clay layer. Then the effect of Spudcan diameter on the punch failure and the interaction between Spudcan and soil on two-layered soil was investigated. The result showed that if the diameter of the Spudcan increased, the bearing capacity decreased. The Spudcan-footprint interaction in a single soil was investigated too. The effect of offset between Spudcan and Footprint on the horizontal force applied the Spudcan was investigated to find the critical distance. According to the results, it was recommended to avoid Spudcan at a distance equal to half of the footprint’s diameter. Also, the effect of soil parameters (C, Phi) and the difference between Spudcan’s and Footprint’s diameters on horizontal force has been investigated. As the Cohesion increases, the applied horizontal force increases, with the maximum force applied at depths of 0.25 to 0.55 times the diameter of the footprint. As the angle of internal friction of the soil increases, the applied horizontal force increases, with maximum force applied at depths of 0.4 to 0.75 times the diameter of the footprint. In examining the effect of different Spudcan diameter rather than footprint, it was concluded that in cases that the Spudcan diameter is greater than the available footprint diameter, less horizontal force is applied than when the Spudcan and footprint diameter are equal. Finally, the horizontal force applied to the Spudcan in the Spudcan-footprint interaction of the Persian Gulf was investigated.
Keywords: Spudcan, Footprint, spudcan-footprint interaction, punch through failure, Numerical modeling
