Anti-scouring construction method for solidified soil of offshore wind power pile foundation

Abstract

The invention relates to an offshore wind power pile foundation solidified soil anti-scour construction method which comprises the following steps that terrain sweeping measurement is conducted on a scour pit before construction, and the construction volume and the hydraulic reclamation point location of hydraulic reclamation repair are determined according to data obtained through sweeping measurement; the solidified soil is conveyed to the area position 3-5 m near the hydraulic reclamation point position through the workboat, and four-anchor positioning is conducted on the workboat through the anchor boat; solidified soil on a workboat is blown and filled into a scouring pit through a conveying pump, the blowing and filling construction steps are determined according to data obtained through side sweeping during blowing and filling, a pipe opening makes contact with a natural seabed surface during blowing and filling to conduct solidified soil blowing and filling, and a solidified soil covering quilt is formed around the wind power pile foundation through the self-flowing property of the solidified soil. A solidified soil structure constructed and formed by the solidified soil anti-scouring construction method for the offshore wind power pile foundation has high durability, and the anti-scouring capacity of the single pile foundation can be greatly improved.

Description

Technical Field

[0001] This application relates to the technical field of offshore wind power engineering, and specifically relates to a construction method for preventing scouring of solidified soil for offshore wind power pile foundations. Background Technique

[0002] Offshore wind power foundations are continuously affected by waves and tides for a long time. Especially for large-diameter monopile foundations, the sea current will continuously scour and erode the soil around the pile, and further form a scouring pit. The depth of scouring increases with the increase of the pile diameter. The formation of the scouring pit will reduce the embedded depth of the pile foundation, which reduces the natural frequency of the overall structure of the wind turbine and has an adverse impact on the safe operation of offshore wind turbines. For the problem of scouring of monopile foundations, one solution is to use various anti-scouring measures to protect the foundation. Some existing scouring protection measures mainly include throwing stones and sinking concrete continuous rows. For the method of throwing stones, although its construction process is simple and the cost is low, because the stone-throwing structure is underwater, restricted by technology and environment, its quality is difficult to guarantee, and the protection effect sometimes fails to reach the expected level. And the sinking of concrete continuous rows involves very complicated process links, which need to be closely connected before and after, and the crimping accuracy requirements between different structures are high. It often requires manual underwater exploration to ensure the construction quality, which greatly increases the construction cost. Affected by various factors such as self-sinking and scouring damage of sea currents, the structure of the thrown stones may be damaged and a new scouring pit may be formed around the pile again. The failure of anti-scouring measures to fully play their role will seriously affect the safe operation of wind turbines and increase the operation and maintenance costs of the wind farm. This situation has become an urgent problem in the field. Summary of the Invention

[0003] This application provides a construction method for preventing scouring of solidified soil for offshore wind power pile foundations. The solidified soil structure constructed by this construction method for preventing scouring of solidified soil for offshore wind power pile foundations has strong durability and can greatly improve the anti-scouring ability of monopile foundations.

[0004] The construction method for preventing scouring of solidified soil for offshore wind power pile foundations provided by this application mainly includes the following steps: Conduct topographic survey of the scouring pit before construction, and determine the construction volume and filling points for filling and repairing according to the data obtained from the survey;

[0005] Transport the solidified soil to the area 3-5m near the filling point by a working ship, and use an anchor boat to position the working ship with four anchors;

[0006] Blow the solidified soil on the working ship into the scouring pit through a transfer pump. When blowing, determine the blowing construction steps according to the data obtained from the survey. When blowing, contact the natural seabed surface with the pipe orifice to blow the solidified soil, and use the self-flowing property of the solidified soil to form a solidified soil covering layer around the wind power pile foundation.

[0007] In an alternative solution, when the maximum scouring depth h of the scouring pit ≤ 1 m, the dredger fill construction steps include:

[0008] First, fill the scouring pit with solidified soil, and then continue to fill the solidified soil on the filled surface to the protection range, where the protection range is 2 - 3 times the diameter of the wind power pile, and the thickness of the solidified soil around the wind power pile is greater than 0.8 m.

[0009] In an alternative solution, when the maximum scouring depth 1 m < h ≤ 3 m of the scouring pit, the dredger fill construction steps include:

[0010] First, fill the scouring pit with solidified soil, and then continue to fill the solidified soil on the filled surface until the solidified soil on the filled surface naturally slopes and flows to the protection range, where the protection range is 2 - 3 times the diameter of the wind power, and the slope ratio of the formed natural slope is greater than 1:10.

[0011] In an alternative solution, when the maximum scouring depth h > 3 m of the scouring pit and the shape of the scouring pit is long and narrow and the scouring range is less than the predetermined range, the dredger fill construction steps include:

[0012] First, directly fill the scouring pit with solidified soil, and then continue to fill the solidified soil on the filled surface until the solidified soil on the filled surface naturally slopes and flows to the protection range, where the protection range is 2 - 3 times the diameter of the wind power pile, and the slope ratio of the formed natural slope is greater than 1:10.

[0013] In an alternative solution, when the maximum scouring depth h > 3 m of the scouring pit and the scouring range of the scouring pit is greater than the predetermined range, the dredger fill construction steps include:

[0014] Directly fill the scouring pit with solidified soil to the protection range, where the protection range is 2 - 3 times the diameter of the wind power pile. After the filling is completed, the elevation of the beach surface around the pile is about 2.0 m lower than the elevation of the surrounding seabed.

[0015] In an alternative solution, when filling with solidified soil, it is necessary to strictly control the pumping rate and / or pumping angle. After the filling of the solidified soil is completed, the following steps are also included:

[0016] Inspect the solidified soil after the filling is completed. After reaching the preset elevation, cure the solidified soil under the same on-site conditions until the specified age;

[0017] Conduct project acceptance.

[0018] In an alternative solution, the time for the reclamation of solidified soil is two hours before and after the high and low slack tides. When reclaiming the solidified soil, 3 to 4 solidified soil reclamation points can be arranged to facilitate the even distribution of the solidified soil around the wind power pile foundation. The prepared solidified soil needs to be reclaimed within 2 hours.

[0019] The beneficial effects of the present application are as follows:

[0020] In the construction method for preventing scouring of the solidified soil for the offshore wind power pile foundation in the present application, marine silt resources are utilized for chemical solidification, and then the solidified soil is directly reclaimed around the pile foundation through a delivery pump. Relying on the self-flowing property of the solidified soil slurry, it flows automatically to the area to be protected, thereby filling the scour pits formed under different working conditions around the pile foundation. The solidified soil slurry gradually changes from a liquid state to a solid state resistant to scouring, and its strength gradually increases with the development of the coagulation process, and finally an integral solidified soil bottom protection structure is formed around the wind power pile. Such a reclamation construction method does not need to be close to the pile foundation during construction operations, which can greatly reduce the accidental damage caused by collision with the pile foundation in traditional construction. The reclaimed solidified soil is in a flowing state in the early stage and will not pose potential safety hazards such as damage to the pile body like traditional processes such as rock throwing and sandbagging.

[0021] It should be understood that the above general description and the following detailed description are only exemplary and do not limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the construction flow chart of the construction method for preventing scouring of the solidified soil for the offshore wind power pile foundation provided by the present application;

[0023] Figure 2 is the schematic diagram of the working ship during four-anchor positioning in the present application;

[0024] Figure 3 is the schematic diagram of the first embodiment of the construction method when reclaiming the solidified soil for the scour pit;

[0025] Figure 4 is the schematic diagram of the second embodiment of the construction method when reclaiming the solidified soil for the scour pit;

[0026] Figure 5 is the schematic diagram of the third embodiment of the construction method when reclaiming the solidified soil for the scour pit;

[0027] Figure 6 is the schematic diagram of the fourth embodiment of the construction method when reclaiming the solidified soil for the scour pit.

[0028] The accompanying drawings here are incorporated into the specification and constitute a part of the specification, showing the embodiments in line with the present application, and are used together with the specification to explain the principles of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] To better understand the technical solution of the present application, the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0030] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other technical solutions obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0031] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms of "a", "the" and "said" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0032] It should be understood that the term " / and" used herein is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0033] As Figures 1-6 shown, the embodiments of the present application provide a construction method for preventing scouring of solidified soil for offshore wind power pile foundations. The construction method for preventing scouring of solidified soil for offshore wind power pile foundations mainly includes two major links: preliminary preparation work and filling of solidified soil. The solidified soil required can adopt the sludge solidification technology, with sludge solidified soil as the main material, which is convenient for transportation and use. Compared with the traditional scheme, it can effectively control the construction quality, and has no impact on the pile body during the construction process. The finally formed solidified soil structure has strong durability, thus effectively improving the anti-scouring ability of the single-pile foundation and achieving good technical and economic effects.

[0034] Specifically, the construction method for preventing scouring of solidified soil for offshore wind power pile foundations mainly includes the following steps:

[0035] First, conduct a topographic survey of the scour pit before construction, and determine the construction volume and filling points for filling and repair according to the data obtained from the survey; the survey map can provide accurate data for the filling and repair project volume, current topography, elevation difference of the beach, submarine cable routing map, etc.;

[0036] Precast the solidified soil and make other preparations. Sufficient solidified soil for construction should be prepared in advance to ensure the uninterrupted supply of construction materials. At the same time, for the offshore operation environment, do a good job in rain and moisture protection; after the preparation is completed, transport the solidified soil to the area 3-5m near the filling point through a working ship. Specifically, as Figure 2As shown in the figure, according to the position map and coordinate points of the wind turbine pile foundation that needs anti-erosion protection, the deck barge after transformation (installed with rotating telescopic suspension rods, mud storage bins, filling pumps, etc.) is accurately positioned at a position 3-5 m away from the wind power pile, and the operation ship is positioned with four anchors by an anchor boat;

[0037] The solidified soil on the operation ship is filled into the scouring pit through a delivery pump. During the filling process, the filling construction steps are determined according to the data obtained by sounding. During the filling, a special delivery pump for solidified soil can be used. Through the short-distance delivery pipeline installed on the positioning deck barge traveling vehicle and the developed mud discharge pipe head (equipped with a device that can reduce the flow velocity of the solidified soil delivery and position on the seabed), the pipe orifice contacts the natural seabed surface to start filling the solidified soil. Utilizing the self-flow property of the solidified soil, a solidified soil covering is formed around the wind power pile foundation. During the filling of the solidified soil, the pumping rate and / or pumping angle need to be strictly controlled;

[0038] The filled solidified soil is inspected. After reaching the preset elevation, the solidified soil is cured under the same conditions on site until the specified age; finally, the project acceptance is carried out.

[0039] In the construction method for preventing erosion of the solidified soil for the offshore wind power pile foundation in this embodiment, the marine silt resources are utilized for chemical solidification, and then the solidified soil is directly filled around the pile foundation through a delivery pump. Relying on the self-flow property of the solidified soil slurry, it flows to the area to be protected, thereby filling the scouring pits formed under different working conditions around the pile foundation. The solidified soil slurry gradually changes from a liquid state to a solid state resistant to erosion, and its strength gradually increases with the development of the coagulation process, and finally an integral solidified soil bottom protection structure is formed around the wind power pile. Such a filling construction method does not need to be close to the pile foundation during construction operations, which can greatly reduce the accidental damage caused by the collision of the pile foundation in traditional construction. The filled solidified soil is in a flowing state in the early stage and will not cause potential safety hazards such as damage to the pile body like traditional processes such as throwing stones and sandbags.

[0040] After the solidified soil is formed, it has good stability and durability. This construction method hardly needs to be filled and repaired after construction, and no maintenance cost will be generated in the later stage. Through comprehensive calculation, due to the different depths and sizes of the scouring pits around the pile, there are differences in the filling volume. The cost for implementing the solidified soil anti-erosion method for a single pile foundation is about 100,000 - 220,000 yuan.

[0041] As Figure 3 shown, in a specific embodiment, when the maximum scouring depth h of the scouring pit ≤ 1 m, the filling construction steps include:

[0042] First, use the solidified soil to fill the scouring pit, and then continue to fill the solidified soil on the filled surface to the protection range. The protection range is 2 - 3 times the diameter of the wind power pile (if the diameter of the wind power pile is defined as D, then the protection range is 2D - 3D), and the thickness of the solidified soil around the wind power pile is greater than 0.8 m.

[0043] As Figure 4 shown, in a specific embodiment, when the maximum scouring depth of the scouring pit satisfies 1m < h ≤ 3m, the dredger fill construction steps include:

[0044] First, fill the scouring pit with solidified soil, and then continue to fill the filled surface with solidified soil until the solidified soil on the filled surface naturally slopes and flows to the protection range, where the protection range is 2 - 3 times the diameter of the wind turbine (if the diameter of the wind turbine pile is defined as D, then the protection range is 2D - 3D), and the slope ratio of the formed natural slope is greater than 1:10.

[0045] As Figure 5 shown, in a specific embodiment, when the maximum scouring depth of the scouring pit h > 3m, and the shape of the scouring pit is long and narrow, and the scouring range is less than the predetermined range, the dredger fill construction steps include:

[0046] First, directly fill the scouring pit with solidified soil, and then continue to fill the filled surface with solidified soil until the solidified soil on the filled surface naturally slopes and flows to the protection range, where the protection range is 2 - 3 times the diameter of the wind turbine pile (if the diameter of the wind turbine pile is defined as D, then the protection range is 2D - 3D), and the slope ratio of the formed natural slope is greater than 1:10.

[0047] As Figure 6 shown, in a specific embodiment, when the maximum scouring depth of the scouring pit h > 3m, and the scouring range of the scouring pit is greater than the predetermined range, the dredger fill construction steps include:

[0048] Directly fill the scouring pit with solidified soil to the protection range, where the protection range is 2 - 3 times the diameter of the wind turbine pile (if the diameter of the wind turbine pile is defined as D, then the protection range is 2D - 3D). After the filling is completed, the elevation of the beach surface around the pile is about 2.0m lower than the elevation of the surrounding seabed.

[0049] It should be added that during the dredger fill, the dredged silt solidified soil should be stirred evenly. The time for solidified soil dredger fill is two hours before and after high and low slack tides. When carrying out the solidified soil dredger fill, 3 - 4 solidified soil dredger fill points can be arranged to facilitate the even distribution of the solidified soil around the wind turbine pile foundation, and the prepared solidified soil needs to be filled within 2 hours.

[0050] During construction, attention should be paid to construction quality inspection. The construction quality inspection can be divided into quality inspection during the construction process and overall project inspection after completion. Test inspection: Take samples of the solidified soil loose soil for molding, cure it naturally in seawater, and conduct unconfined compressive strength tests. The test age is 28d, and the standard solidified soil strength is greater than 400kPa. Detection by sounding and scanning: After the dredger fill is completed, the solidified soil forms naturally and cures naturally. Detect the retention and forming situation of the solidified soil in the form of sounding and scanning, and use the sounding and scanning results as the acceptance basis.

[0051] As can be seen from the above embodiments, the construction method for preventing scouring of solidified soil for offshore wind turbine pile foundations provided by the present application can be well applied to the scouring protection of single pile foundations for offshore wind turbines. For the scour pits with different shapes and depths formed around the piles after pile driving construction due to different sea current flow patterns and different scouring times, different types of protection forms of this construction method can be adapted to them. According to the actual situation of the scour pits, the protection form is adjusted and the protection design is optimized to reduce the protection cost while meeting the protection effect. This construction method is mainly applicable to the foundation protection construction with a water depth of less than 30m at the pile position.

[0052] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A construction method for preventing scouring of solidified soil in an offshore wind power pile foundation, characterized in that, It includes the following steps: Conduct a topographic survey of the scour pit before construction, and determine the construction volume and filling points for reclamation repair based on the data obtained from the survey; Transport the solidified soil to the area 3 - 5m near the filling point by a working ship, and use an anchor boat to position the working ship with four anchors; Blow the solidified soil on the working ship into the scour pit through a delivery pump. During the filling process, determine the filling construction steps according to the data obtained from the survey. When filling, contact the natural seabed surface with the pipe mouth to blow the solidified soil, and use the self - flowing property of the solidified soil to form a solidified soil covering around the wind power pile foundation.

2. The construction method for preventing scouring of solidified soil of an offshore wind power pile foundation according to claim 1, characterized in that, When the maximum scour depth h of the scour pit ≤ 1m, the filling construction steps include: First, fill the scour pit with the solidified soil, and then continue to fill the solidified soil on the filled surface to the protection range. The protection range is 2 - 3 times the diameter of the wind power pile, and the thickness of the solidified soil around the wind power pile is greater than 0.8m.

3. The construction method for preventing scouring of solidified soil of an offshore wind power pile foundation according to claim 1, wherein, When the maximum scour depth 1m < h ≤ 3m of the scour pit, the filling construction steps include: First, fill the scour pit with the solidified soil, and then continue to fill the solidified soil on the filled surface until the solidified soil on the filled surface naturally slopes and flows to the protection range. The protection range is 2 - 3 times the diameter of the wind power pile, and the slope ratio of the formed natural slope is greater than 1:

10.

4. The construction method for preventing scouring of solidified soil for offshore wind power pile foundation according to claim 1, characterized in that When the maximum scour depth h of the scour pit > 3m, and the shape of the scour pit is long and narrow, and the scour range is less than the predetermined range, the filling construction steps include: First, directly fill the scour pit with the solidified soil, and then continue to fill the solidified soil on the filled surface until the solidified soil on the filled surface naturally slopes and flows to the protection range. The protection range is 2 - 3 times the diameter of the wind power pile, and the slope ratio of the formed natural slope is greater than 1:

10.

5. The construction method for preventing scouring of solidified soil of an offshore wind power pile foundation according to claim 1, characterized in that, When the maximum scour depth h of the scour pit > 3m, and the scour range of the scour pit is greater than the predetermined range, the filling construction steps include: Blow the scour pit directly with the solidified soil to the protection range. The protection range is 2 - 3 times the diameter of the wind power pile. After the filling is completed, the elevation of the beach surface around the pile is about 2.0m lower than the elevation of the surrounding seabed.

6. The construction method for preventing scouring of solidified soil of an offshore wind power pile foundation according to any one of 1-5, characterized in that When blowing the solidified soil, it is necessary to strictly control the pumping rate and / or pumping angle. After the solidified soil filling is completed, the following steps are also included: Inspect the filled solidified soil. After reaching the preset elevation, cure the solidified soil under the same on - site conditions until the specified age; Conduct project acceptance.

7. The construction method for preventing scouring of solidified soil of an offshore wind power pile foundation according to claim 6, characterized in that, The time for blowing the solidified soil is two hours before and after high and low slack tides. When blowing the solidified soil, 3 - 4 solidified soil filling points can be arranged to facilitate the uniform distribution of the solidified soil around the wind power pile foundation. The prepared solidified soil needs to be blown out within 2 hours.

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