| As the demand for oil and gas is increasing and the development of marine petroleum exploitation technology, hydrocarbon production has progressively moved into deep and ultra deep waters, the development of marine petroleum exploitation has become the focus of the world, so the development of marine oil and gas exploitation is important for our country’s economy sustainable development. In this situation, the Steel Catenary Risers have been widely used.The steel catenary riser is composed of Sag Bend and touchdown zone. Cyclic interaction of the riser with the seabed under vessel motions and hydrodynamic loading strongly affects risers’ fatigue life, which is the hot spot of the international ocean engineering research.This research performs a detailed discussion on touchdown zone based on the global analysis for the steel catenary riser. The main content of the research is as follows:(1)Global analysis for the steel catenary riser. Compared with the catenary equation, the initial static equilibrium configuration of the SCR based on the installation process is closer to the realistic. Results show that the region of high stress and high stress amplitude are generally located at the top hanging and bottom touchdown zone, which are the research focus.(2)Presenting two load-deflection (P-y) models (non-degradation and degradation models) to simulate seafloor-riser interaction. Using ABAQUS explicit finite element methods to study seabed response and trenching. Results are compared with NGI tests to verify load-deflection (P-y) models. Subsequently, analyze the effect of cohesive force, internal friction Angle, elastic modulus and friction coefficient on soil resistance.(3)Simulating the seafloor-pipe interaction as a flexible pipe supported on a bed of springs by finite difference method, comparing with the finite element method. The influence factors of load deflection, soil stiffness, soil suction on the SCR touchdown zone deformation and bending stress are studied. |
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