Method of Reducing Construction Settlement of Underground Jacket Foundation in Offshore Booster Station

Abstract

The invention provides a method for reducing the construction settlement of the bottom-mounted jacket foundation of an offshore step-up station, which includes the following steps: S1, arranging a buoyancy device on the bottom-mounted jacket foundation; S2, using a crane to lift the jacket foundation , together with the buoyancy device, is sunk into the seabed as a whole, and the jacket foundation is located behind the mud surface of the seabed, and the pile sinking and concrete grouting construction are carried out; S3, after the concrete grouting is completed for a period of time, the concrete between the jacket foundation and the pile reaches the expected strength , remove the buoyancy device. The invention utilizes the buoyancy device arranged on the foundation of the booster station to provide buoyancy, reduces the pressure of the foundation of the booster station on the seabed mud surface, thereby achieving the purpose of reducing settlement, has strong operability, easy implementation of resources, and no adverse effects on the body structure The impact and buoyancy can be adjusted according to the needs, and the applicability is strong, which can solve the settlement problem of the bottom-siting jacket relatively quickly and at low cost.

Description

technical field [0001] The invention belongs to the field of foundation construction of an offshore booster station in an offshore wind farm project, and more particularly relates to a method for reducing the construction settlement of a bottom-mounted jacket foundation of an offshore booster station. Background technique [0002] An offshore wind farm is an offshore power transmission and transformation facility that collects the electrical energy generated by each wind turbine and boosts and sends electrical energy. An offshore booster station generally includes a lower foundation and an upper block. The lower foundation supports the upper block and the upper block. The block is the integration of power transmission and transformation equipment, and the lower foundation can be of various types such as jacket (truss member made of steel structure) or single pile (single columnar member made of steel structure). The bottom-mounted jacket foundation is a jacket-type foundatio...

AI Technical Summary

Problems solved by technology

[0003] The offshore booster station is the core power transmission and transformation facility of the offshore wind farm. According to the regulations, the first deck should not be flooded under the extreme wind and waves that occur once in 100 years. In this way, the final elevation of the foundation top of the booster station should meet the design requirements. requirements, but the geological conditions of the seabed are complex, especially on the surface, there are often floating mud and soft sediment, and the thickness is not necessarily uniform. The bottom of the jacket foundation is relatively large, generally exceeding 30 meters in length and width, and weighing more than 1,600 tons , when the jacket is seated on the mud surface, the mud surface is not enough to bear the pressure brought by the jacket, and the jacket foundation will settle

The construction of the offshore booster station needs to ensure that the level deviation of each corner of the jacket is within a controllable range, but the existing survey techniques and design calculations cannot give accurate settlement values, so the settlement may be too large to meet the requirements. Design requirements

[0004] The existing technology adopts the method of increasing the design margin in the elevation direction of the jacket before construction and increasing the height in the elevation direction of the jacket after construction to avoid excessive settlement and fail to meet the design requirements

Among them, increasing the design margin in the elevation direction of the jacket is to pre-increase the design margin in the elevation direction of the jacket to preventively solve the problems caused by the measurement error of the mud surface water depth and the inaccurate settlement calculation, but the jacket height involves the entire conduit The strength and stability of the frame mechanism, increasing the design margin will undoubtedly increase the steel consumption and prefabrication cost, and the increase in structural size and weight will not only affect downstream construction investment and construction difficulty, but also affect the overall strength and stability

Increasing the height of the jacket in the elevation direction after construction is an emergency measure after construction. When the top elevation of the jacket is found to be insufficient after construction, the four upright columns are lengthened and heightened at the top of the jacket, and a section of the same pipe fittings is welded. It is an emergency measure, and there are also many defects: 1) The cycle of steel material preparation, prefabrication, and Shanghai welding will take 2 to 3 months, which will be unbearable for the progress of offshore wind power projects; 2) The offshore conditions are limited and the construction is difficult 3) The height that can be increased needs to be designed and calculated, and it cannot be increased without limit, and there is a risk of dissatisfaction; 4) The investment in materials, ship machinery, and manpower is very large, which directly causes the project cost Increase

[0007] 1) As the area of ​​the anti-settling plate increases, the construction difficulty of leveling the jacket foundation increases, resulting in a sharp increase in construction quality risks. Once the standard is exceeded, it is difficult to effectively correct the deviation;

[0008] 2) As the area of ​​anti-sinking plates increases, the amount of steel used increases. For example, the weight of anti-sinking plates of a project has invested about 80 tons of steel plates. At the same time, the requirements for transport ships and lifting ships have increased, which directly leads to an increase in project costs;

[0009] 3) The submarine mud surface in many sea areas "exists floating mud with uneven thickness, which is saturated, flow-plastic, and fluid", and the anti-settling plate needs to be uniformly equipped with drainage holes, and increasing the area of ​​​​the anti-settling plate cannot fundamentally solve the problem. Settlement problem

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