Mechanical Analysis On Underwater Leveling-gripping System Of Jacket And Experimental Research

Jacket platform mainly consists of jacket, steel pipe pile and the upper part. Jacket as aplatform base must be leveling in the installation process, the level of accuracy directly affectsthe platform safety, adaptability, service life and other properties. In deeper water jacketleveling process including the levelling stage and clamping stage, the specialleveling-gripping system is required. According to " The hydraulic equipment of deep waterjacket installation research and development " which the comprehensive scientific researchproject of CNOOC requirement, in this paper, the jacket leveling system is analyzed andstudied, jacket clamping device and leveling system prototype which applicable to domesticproduction is designed, solve the current problems of leveling-gripping system. It mainlyincludes the following aspects.Mechanical system structure including skirt pile gripper and jacket leveling equipment isdesigned, the leveling-gripping system work process is determined, the three-dimensionalmodel is established. According to the designed structure, the key parts mechanical propertiesof skirt pile gripper and jacket leveling equipment is analyzied, through the analysis to verifythe design of jacket leveling-gripping system mechanical structure can meet the levelingperformance requirements. On the basis of shell elastoplastic, stability theory, the limitclamping force which clamped pipe pile and the casing in the leveling process required isconfirmed.The mathematical model is established, which is used to analyze the clamping force,clamping claw tooth embedded depth and system bearing capacity. The nonlinear relationshipbetween clamping force and gripper embedding depth is analyzied by the LS-DYNA softwareto display dynamic analysis, the result shows that clamping force and embedding depth in thestage of plastic deformation have a linear relationship, and draw a relationship betweenclamping hydraulic cylinder pressure and the bearing capacity of leveling-gripping system.Finite element method is used to analyz clamp claw tooth stress intensity, through the analysisto determine the clamping claw structure and material. The leveling-gripping system key partsusing ANSYS to check the strength, the sleeves which have apparent material waste areoptimized. According to the requirements, a new type of alloy steel is developed, the chemicalcomposition of the materials is designed, the experimental gripper material microstructure is analyzed, the properties of alloy steel is studied in different annealing temperature andholding time, the optimal annealing and quenching tempering explosive art is determined.This paper select a platform locate in South China Sea for leveling object, and accordingto the waters of the sea, the effect of wave load on offshore structure is studied based on theMorrison formula and the Stokes5order wave theory. In order to get a leveling-grippingsystem dynamic response in the time domain, according to the parameters of the P-Mspectrum, based on the Shinozuka theory, the effect of wave load in the time domain isanalyzed. The effect of ocean current and wind load on the jacket structure is studied asconstant load. The extreme sea state under different return period is determined, the mainenvironmental load and its combination which jacket withstand in leveling proces is defined.With SACS software, according to the South China Sea, a platform bottom dynamic responseis calculated under limit environmental load in different return period. Use ADAMS softwareto the leveling-gripping system for dynamic analysis in leveling process, the key clampingcontact site dynamic response is determined, the leveling-gripping system can bear thegreatest environmental load is determine,and presents a extreme weather leveling solution.The drawbacks and problems of traditional leveling method is analyzed, aiming at theseproblems, leveling device hydraulic system and jacket leveling control system are designed,include the establishment of leveling-gripping system geometric model, making optimalleveling strategy, designing fuzzy controller based on Mamdani, establishing themathematical model of controlled object. Using software to establish the leveling controlsystem simulation model, leveling-gripping system leveling process simulation is simulatedwithout the environmental load influence and under the environmental load respectively, fromthe result of the simulation, we know leveling control system efficiency, precision isobviously improves compare with the traditional leveling method, can overcome the effect ofenvironmental load, has strong robustness.In the experimental part, this paper determines the leveling-gripping system claw castingprocess, prepare the sample for claw, make claw material for experimental research, andthrough the experiment to determine its strength. The embedded wedge booster clampingmechanism experimental prototype is designed and developed, the relevant experimentalresults compare with theoretical analysis, which varify the gravity self-locking function ofleveling device clamping mechanism and the theoretical analysis is correct. The pile gripper prototype is designed and developed, oil source and the hydraulic cylinder experiment iscarried out to verify the pressure maintaining performance of pile gripper. The grippingperformance experiment under the actual working conditions is carry out in a harbor, theexperimental monitoring results show that pile gripper can meet the practical steel pipe pileclamping requirements. The depth in surface and the clamping claw tooth fracture forms isanalyzed, the analysis results points further optimizing direction for the improvement of theclamping claw tooth structure and improve the leveling-gripping system grippingperformance, and can provides the valuable basis for leveling-gripping system practicalapplication.