Reduction method for basic wave current vibration of offshore wind power single pile

Abstract

The invention relates to a reduction method for basic wave current vibration of an offshore wind power single pile. A flexible damping device is arranged outside the basic wall surface of the single pile, wave currents are smoothed and flowing states are improved by utilizing a wing-shaped wall surface with a short head and a long tail, various water power stimulations are reduced from vibration sources, and passed loads are separated and absorbed through viscoelastic damping materials, so that the purpose of reducing pile foundation vibration is achieved. According to the reduction method for the basic wave current vibration of the offshore wind power single pile, the damping device which automatically moves up and down along water level change is always in a main stimulation area of the wave currents by changing water body weights inside a balancing water tank and adjusting relative position of a device and the water surface and under combined actions of the gravity and buoyancy force, the damping device enables the head and tail to be maintained consistent with wave current directions and plays role in damping flexibly along with change of wave current directions under combined actions of head pressure and tail suction of the wing-shaped overflowing wall surface. The reduction method for the basic wave current vibration of the offshore wind power single pile has the advantages of enabling the pile foundation vibration to be reduced by more than 70 % and being simple in structure and convenient to achieve.

Description

technical field [0001] The invention relates to a vibration reduction method, in particular to a method for reducing wave and tidal current excitation of offshore wind power single pile foundations, and belongs to the field of engineering vibration reduction. Background technique [0002] Wind power is the most rapidly developing clean energy in recent years. Offshore wind energy resources are abundant and stable. Offshore wind power has become the focus of investment and development in all countries in the world. Europe is at the forefront of the world, and my country is still in its infancy. According to the Second Five-Year Plan, the installed capacity of offshore wind power will reach 5 million kilowatts by 2015, which indicates that my country will usher in a period of rapid development of offshore wind power. [0003] There are many types of offshore wind power foundations, mainly including gravity type, pile foundation, jacket, floating type, etc. Each type includes va...

AI Technical Summary

Problems solved by technology

[0004] With the increasing size of wind turbines, the high-rise structure composed of wind turbines-towers-foundation has serious dynamic stability problems. Especially compared with onshore wind power, offshore wind power is also subject to wave and tidal loads, and structural dynamic safety issues are becoming more complex.

Wave flow hydrodynamic loads mainly include wave breaking impact, tidal current pulsation, vortex shedding, vortex excitation around flow, etc. Various loads are complex and changeable, and the main frequency of excitation is low, which is very close to the natural vibration frequency of the fan support structure, which is easy to induce structural resonance , threatening the safe and reliable operation of wind turbines

Therefore, when designing a wind power structure, it should first be considered that the deviation between the natural vibration frequency of the structure and the excitation frequency of the dynamic load is more than 20% to 30% to avoid resonance. The main measure is to increase the natural frequency of the structure as much as possible. It is a thin-walled towering structure, and it is difficult to effectively change the inherent properties of the whole by local structural enhancement

At present, the vibration reduction measures of the wind turbine support structure mainly refer to the offshore platform, and the damper is used to reduce the vibration response. This method belongs to the passive vibration reduction after the vibration occurs. The input of the excitation load does not change, the vibration reduction effect is not obvious, and it is difficult to eliminate the hidden danger of resonance. Moreover, under the long-term action of waves and currents, the fatigue damage of pile foundations cannot be prevented.

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