A horizontal cyclic loading system and loading method suitable for vibration tests of offshore wind turbine pile foundations

Abstract

The invention relates to a horizontal cyclic loading system and method applicable for vibration test of an offshore wind turbine pile foundation. The horizontal cyclic loading system comprises a platform motion structure used for setting a vibration position, a horizontal cyclic loading structure used for controlling the vibration frequency and amplitude of the pile foundation, and a pile foundation fixing structure applicable for various pile diameters, wherein the platform motion structure is arranged on the top of a test water tank, and the horizontal cyclic loading structure is installed on a platform provided by the platform motion structure, and can be rotated around the pile foundation by 360 DEG; and the pile foundation fixing structure is connected to the horizontal cyclic loadingstructure through rotating rods. The horizontal cyclic loading system is simple in principles and easy to operate, and the amplitude of the horizontal cyclic load can be kept constant in test; meanwhile, the vibration frequency of the pile foundation and the included angle between the wave current and the natural vibration direction of a pile can be controlled in real time; and additionally the horizontal cyclic loading system can be further suitable for pile foundations of different sizes.

Description

technical field [0001] The invention relates to a horizontal cyclic loading system and a loading method suitable for vibration tests of pile foundations of offshore wind turbines, and belongs to the technical field of indoor model test equipment for dynamic characteristics of pile foundations of offshore wind turbines. Background technique [0002] Wind energy has attracted extensive attention and research from governments, enterprises, and scholars around the world due to its advantages of huge reserves, renewable, wide distribution, and less pollution. my country's total wind energy reserves are about 3.226 billion kW, and about 1 billion kW of wind energy can be developed. From the perspective of wind energy sources, wind energy can be divided into onshore wind energy and offshore wind energy. Among them, offshore wind energy resources have large reserves, high wind speed, low wind shear, low turbulence, low noise pollution and do not occupy arable land. In the context ...

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Problems solved by technology

Using the former method of applying cyclic loads, it is easy to disturb the soil; the cyclic loading device based on the gear structure has been published as an invention patent. Apparatus and method for cyclic loading (CN201510624557.7), but the device controls that the applied external force remains constant, but the vibration amplitude gradually changes with the passage of vibration time, and it is impossible to apply a constant amplitude horizontal cyclic load. Therefore, at the present stage of research It is not convenient to quantify the pile-soil effect

[0005] In addition, under the actual complex wind and walrus conditions, the vibration direction of the pile foundation is not in the same direction as the direction of the external load (wave, flow), and no one has studied whether it will increase or decrease the erosion when it is reflected in the action of the pile and soil. In addition, At present, most of the research is on the pile-soil action of the pile foundation with constant frequency continuous vibration. In actual offshore projects, the sea breeze changes rapidly, and the frequency of the corresponding fan is also changing all the time. Whether the frequency change will affect the pile-soil action is also a question worth studying; Finally, in the similar test devices designed by other scholars at present, the connection between the pile foundation and the force-applying device is fixed. If the influence of the change of the pile diameter is studied, it is difficult to disassemble and replace the pile foundation after the test. limited

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