Design and Testing of Inertial System for Landslide Displacement Distribution Measurement

Landslide displacement monitoring plays a fundamental role in the study of landslide evolution mechanisms, forecasting, risk assessment, prevention, and control. To fill the deficiencies of traditional instrumentation for measuring landslide displacement distributed along lateral direction, a landslide displacement measurement method based on deformation-coupled pipeline trajectory measurement is proposed, and a pipeline trajectory inertial measurement instrument is developed. The developed instrument, primarily comprised of a single shaft gyro, two axis accelerometers, and an external roller encoder, is designed as an axial half strapdown-radial half platform structure combined with a mechanical gravity platform. This structure avoids the singularity of pitch angle and roll angle and can expediently calculate a pipeline trajectory with an Eulerian transformation when obtaining several basic physical variables, e.g., the axial linear velocity, pitch angle, roll angle, and azimuth angle. Additionally, the pipeline trajectory, measured at different times, possesses the ability to reflect the displacement evolution feature of landslides. The results of prototype simulation tests imply a single measurement accuracy of a 12 cm/100 m span and a singly periodic multiple (more than five times) measurement accuracy of a 3 cm/100 m span, which meets medium-precision displacement measurement requirements for a landslide. Additionally, the finished instrument has been successfully applied to the deformation monitoring of the Majiagou I# landslide, which further verifies its feasibility and offers a reference for similar landslides.

Numerical analysis of varies geometries on dynamic analysis on the gravity platform

On Gravity platform Dynamic Response is a support structure held in place by gravity. Given that the gravity platforms are supportedby the sea bed but not attached to the ground, the motion of them is known as a rocking fluctuation. During the fluctuations, theplatform maybe overturned if the angle is large. In this study, using Ansys Aqwa hydrodynamic software and analytical methods withregard to the performance, the dynamic interaction of platform’s geometry on hydrodynamic forces have been simulated. Theobjective of this study was to analyze the hydrodynamic parameters of the sea and rocking fluctuations of gravity platforms under theimpact of regular wave’s moment considering the soil mechanics and hydrodynamic features of the structure. In order to achievethe objective the hydrodynamic forces using numerical simulations and analytical methods for one column and three hollow columnsplatforms were analyzed. Finally, responses of the platform to irregular waves were studied using numerical simulation. The resultsshowed that with the increasing of the depth, the impact of wave’s force and moment on the base of platform are reduced throughexponential relationship. The reductions are due to the effective depth that is equal to half the wave length. The results suggestthat the response of the rocking motion of gravity platform shows significant changes in relation to height and wavelength. Based onthe curves fitted to the data of the fluctuation angle, sustainability of the platform in the rocking motion can be thoroughly andcompletely investigated.

Study on Thermal Insulation Solutions for Submarine Oil Storage in Offshore Gravity Platform

As application of gravity platform is increasing rapidly in marginal oilfields, the heat preservation performance of the submarine oil tank is becoming more and more important in offshore oil storage technology. In order to enhance heat preservation performance of the concrete oil tank to reduce energy consumption, three insulation solutions were proposed in this paper. Contrastive analysis shows that polyurethane solution can not only maximize economic benefits but also possess high engineering feasibility and environmental value.

Nonlinear Finite Element Analysis of the Stability of Gravity Platform

Gravity platform was widely used in the development of marginal oil field, but the existence of scour pit caused by the flow and wave increasing the possibility to overturn. The paper introduced the no depth contact interface element to simulate the nonlinear effect between the bucket skirt and soil, and introduced the birth-death element to simulate the increasing scour pit. The results provide guidance to prevent overturning.

Evaluation of the Horizontal Wave Forces on Piles

Reliability of offshore platforms is an important issue in the prevention of environmental disasters. In this paper, the variation of the horizontal force exerted on an offshore gravity platform is analyzed to achieve a deep comprehension of a storm scenario. Considering the wave motion as a potential motion, the quasi-determinism theory is applied to obtain the kinematic characteristics of a storm. The evolution of force against time is analyzed through the Morison's equation, diffraction theory, and a simplified method. Moreover, two case studies are examined, one in the Ortona region of the Italian coast and the other in the Gulf of Alaska, USA.

Dynamic Analysis of Gravity Platform's Marine Riser under Wave Load

Gravity platform was widely used in marginal oilfield, so the strength and the stability of its marine riser under wave load became very important. By simplifying the Morison equation, the paper made the dynamic analysis of the riser come down to solving the fourth order non-homogeneous linear differential equation, thus got the analytical solution of its deflection, shear force and bending moment. And the comparison with Ansys simulation showed that this simplified method was feasible.