Offshore wind power pile foundation scour resistant flow state solidified soil material and preparation method and application thereof

Abstract

The application discloses a scouring-resistant flow-state solidified soil material for offshore wind power pile foundation and a preparation method and application thereof, relates to the technical field of offshore wind power foundation protection and geotechnical engineering materials, and is made of the following components in parts by weight: coastal beach sludge: 120-140 parts, based on the weight of sludge with a water content of 60-110%; ordinary Portland cement: 6-10 parts; S95 grade mineral powder: 4-15 parts; cellulose ether: 0.03-0.06 parts; anhydrous sodium sulfate: 0.5-0.8 parts; polycarboxylic acid water reducing agent: 0.02-0.05 parts; and the coastal beach sludge is natural sludge collected from a coastal beach of a sea area where an offshore wind power plant is located, has a salt content of about 1-3% and an organic matter content of less than or equal to 3%. The flow-state solidified soil material has excellent underwater dispersion resistance, high fluidity, moderate strength after hardening and strong scouring resistance.

Description

Technical Field

[0001] This invention relates to the field of offshore wind power foundation protection and geotechnical engineering materials technology, and in particular to offshore wind power pile foundation anti-scour fluidized solidified soil materials, their preparation methods and applications. Background Technology

[0002] Offshore wind turbine foundations face severe localized scour problems. Traditional scour prevention measures (such as riprap, sand sheets, and geotextiles) have shortcomings such as construction difficulties, poor integrity, susceptibility to secondary scour, and high costs.

[0003] Fluidized solidification technology can self-level and self-compact, and is convenient for underwater construction, making it an ideal form of backfill protection for pile foundation scour pits.

[0004] Existing fluidized solidified soils mostly use natural sand or commercial soil, which is costly and does not make full use of the large amount of tidal flat silt generated near marine engineering projects.

[0005] Nearshore mudflat silt has high water content, extremely low strength, and contains organic matter and salt. Conventional cement has poor solidification effect, making it difficult to directly prepare solidified soil that is non-dispersible underwater, highly fluid, and has sufficient erosion resistance after hardening.

[0006] Therefore, there is an urgent need to develop an underwater non-dispersible fluid solidification soil material and corresponding process that can absorb large amounts of tidal flat silt and meet the scour prevention requirements of offshore wind power pile foundations. Summary of the Invention

[0007] This invention provides a fluidized solidified soil material for scour prevention of offshore wind turbine pile foundations, its preparation method, and its application. It provides a fluidized solidified soil material with excellent underwater anti-dispersion properties, high fluidity, moderate strength after hardening, and strong scour resistance, using nearshore tidal flat silt as the main raw material. It also provides a simple and efficient preparation method and its application in scour prevention of offshore wind turbine pile foundations, so as to significantly reduce material costs and realize the resource utilization of silt.

[0008] According to one aspect of this disclosure, a fluidized solidified soil material for erosion protection of offshore wind turbine pile foundations is provided, comprising the following components in parts by weight: nearshore tidal flat slurry: 120-140 parts, based on the weight of slurry with a water content of 60%-110%; ordinary silicate cement: 6-10 parts; S95 grade mineral powder: 4-15 parts; cellulose ether: 0.03-0.06 parts; sodium sulfate: 0.5-0.8 parts; polycarboxylate superplasticizer: 0.02-0.05 parts; The nearshore mudflat silt is natural mud collected from the nearshore mudflats of the sea area where the offshore wind farm is located. It has a salt content of about 1% to 3% and an organic matter content of ≤3%.

[0009] In one possible implementation, the cellulose ether is hydroxypropyl methylcellulose ether with a viscosity specification of 100,000 to 200,000 mPa·s.

[0010] In one possible implementation, the sodium sulfate is industrial anhydrous sodium sulfate with a purity ≥98%.

[0011] In one possible implementation, the polycarboxylate superplasticizer is a powder or liquid with a water reduction rate of ≥25%.

[0012] In one possible implementation, the initial fluidity of the solidified fluid is controlled at 180~250mm, the unconfined compressive strength underwater after 28 days of hardening is ≥0.4MPa, and the cement loss rate during underwater pouring is ≤5%.

[0013] A method for preparing scour-resistant fluidized solidified soil material for offshore wind turbine pile foundations, the method comprising the following steps: S1, silt pretreatment: near-shore mudflat silt is sieved to remove impurities, and the moisture content is tested and adjusted to 60%~110% to obtain silt slurry for use. S2, ordinary silicate cement, S95 grade mineral powder, sodium sulfate and polycarboxylate superplasticizer are premixed evenly in dry powder state to obtain dry-mixed cementitious material; S3, dissolve cellulose ether and polycarboxylate superplasticizer in part of the mixing water to prepare an admixture solution; S4. Add the sludge slurry from step S1 and the dry-mixed cementitious material from step S2 into the mixing device, and add the additive solution from step S3 while stirring. Continue stirring for 2 to 5 minutes until a uniform flow state is reached, and the fluidized solidified soil material is obtained.

[0014] The application of scour-resistant fluidized solidified soil material for offshore wind power pile foundations involves pumping or conveying the prepared fluidized solidified soil material to the scour pits around the pile foundation. Relying on its high fluidity and self-leveling properties, the material fills the entire pit and solidifies directly underwater to form an integral scour-resistant protective layer that is tightly bonded to the pile foundation and the original seabed.

[0015] In one possible implementation, an underwater conduit method is used during construction. The conduit outlet is always buried at least 1m below the surface of the fluidized solidified soil to prevent the conduit from being blocked. At the same time, the working surface should not be too high to prevent water washing and dispersion. After solidification, a slope protection structure is formed with the top surface slightly higher than the original seabed surface.

[0016] Compared with the prior art, the beneficial effects of the present invention are: Extensive use of waste silt: Using tidal flat silt near offshore wind power sites as the main raw material (accounting for more than 55% of the solid components), material costs are significantly reduced, the problems of land occupation and environmental pollution of silt dumps are solved, and local sourcing and waste resource utilization are achieved.

[0017] Strong underwater anti-dispersion properties: The cement is thickened and water-retaining by cellulose ether, and promoted to quickly hydrate and coagulate by sodium sulfate. It also maintains fluidity by polycarboxylate superplasticizer. During underwater casting, the loss of cement particles is extremely low, and the water washing resistance is outstanding.

[0018] Convenient construction and reliable quality: The fluid solidified soil has good fluidity and can be self-leveled and filled in irregular scour pits by pumping or conveying through a conduit. No vibration is required. After hardening, it is homogeneous and dense, forming a good bond with the pile foundation and seabed.

[0019] Mechanical and erosion resistance matching: The pozzolanic effect and micro-aggregate effect of S95 grade mineral powder can improve the later strength and resistance to sulfate erosion; sodium sulfate provides early strength, enabling the solidified soil to form sufficient strength to resist tidal erosion in a short time and has good long-term durability.

[0020] Good environmental compatibility: The pH value and leachate of the solidified soil meet the requirements of marine environmental protection and have little impact on the marine environment. Attached Figure Description

[0021] Figure 1 A flowchart illustrating a method for preparing a flow-solidified soil material for erosion prevention of offshore wind power pile foundations according to an embodiment of this disclosure is shown.

[0022] Figure 2 This diagram illustrates the scour-resistant fluidized solidified soil material used in offshore wind turbine pile foundations to meet the requirements for pumping expansion during construction.

[0023] Figure 3 A schematic diagram of the anti-dispersion state of simulated underwater fluidized solidified soil is shown. Detailed Implementation

[0024] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0025] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0026] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of this disclosure.

[0027] The scour-resistant fluidized solidification soil material for offshore wind turbine pile foundations comprises the following components in parts by weight: nearshore tidal flat slurry: 120-140 parts, based on the weight of slurry with a moisture content of 60%-110%; ordinary silicate cement: 6-10 parts; S95 grade mineral powder: 4-15 parts; cellulose ether: 0.03-0.06 parts; sodium sulfate: 0.5-0.8 parts; polycarboxylate superplasticizer: 0.02-0.05 parts. The nearshore mudflat silt is natural silt collected from the nearshore mudflats of the sea area where the offshore wind farm is located. It has a salt content of about 1% to 3% and an organic matter content of ≤3%.

[0028] In one possible implementation, the cellulose ether is hydroxypropyl methylcellulose ether with a viscosity specification of 100,000 to 200,000 mPa·s.

[0029] In one possible implementation, the sodium sulfate is industrial anhydrous sodium sulfate with a purity ≥98%.

[0030] In one possible implementation, the polycarboxylate superplasticizer is a powder or liquid with a water reduction rate of ≥25%.

[0031] In one possible implementation, the initial fluidity of the solidified fluid is controlled at 180~250mm, the unconfined compressive strength underwater after 28 days of hardening is ≥0.4MPa, and the cement loss rate during underwater pouring is ≤5%.

[0032] Extensive use of waste silt: Using tidal flat silt near offshore wind power sites as the main raw material (accounting for more than 55% of the solid components), material costs are significantly reduced, the problems of land occupation and environmental pollution of silt dumps are solved, and local sourcing and waste resource utilization are achieved.

[0033] Strong underwater anti-dispersion properties: The cement is thickened and water-retaining by cellulose ether, and promoted to quickly hydrate and coagulate by sodium sulfate. It also maintains fluidity by polycarboxylate superplasticizer. During underwater casting, the loss of cement particles is extremely low, and the water washing resistance is outstanding.

[0034] Convenient construction and reliable quality: The fluid solidified soil has good fluidity and can be self-leveled and filled in irregular scour pits by pumping or conveying through a conduit. No vibration is required. After hardening, it is homogeneous and dense, forming a good bond with the pile foundation and seabed.

[0035] Mechanical and erosion resistance matching: The pozzolanic effect and micro-aggregate effect of S95 grade mineral powder can improve the later strength and resistance to sulfate erosion; sodium sulfate provides early strength, enabling the solidified soil to form sufficient strength to resist tidal erosion in a short time and has good long-term durability.

[0036] Good environmental compatibility: The pH value and leachate of the solidified soil meet the requirements of marine environmental protection and have little impact on the marine environment.

[0037] A method for preparing scour-resistant fluidized solidified soil material for offshore wind turbine pile foundations, the method comprising the following steps: S1, silt pretreatment: near-shore mudflat silt is sieved to remove impurities, and the moisture content is tested and adjusted to 60%~110% to obtain silt slurry for use. S2, ordinary silicate cement, S95 grade mineral powder, sodium sulfate and polycarboxylate superplasticizer are premixed evenly in dry powder state to obtain dry-mixed cementitious material; S3, dissolve cellulose ether and polycarboxylate superplasticizer in part of the mixing water to prepare an admixture solution; S4. Add the sludge slurry from step S1 and the dry-mixed cementitious material from step S2 into the mixing device, and add the additive solution from step S3 while stirring. Continue stirring for 2 to 5 minutes until a uniform flow state is reached, and the fluidized solidified soil material is obtained.

[0038] The application of scour-resistant fluidized solidified soil material for offshore wind power pile foundations involves pumping or conveying the prepared fluidized solidified soil material to the scour pits around the pile foundation. Relying on its high fluidity and self-leveling properties, the material fills the entire pit and solidifies directly underwater to form an integral scour-resistant protective layer that is tightly bonded to the pile foundation and the original seabed.

[0039] In one possible implementation, an underwater conduit method is used during construction. The conduit outlet is always buried at least 1m below the surface of the fluidized solidified soil to prevent the conduit from being blocked. At the same time, the working surface should not be too high to prevent water washing and dispersion. After solidification, a slope protection structure is formed with the top surface slightly higher than the original seabed surface.

[0040] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A fluidized solidified soil material for erosion protection of offshore wind turbine pile foundations, characterized in that, It is made from the following components in parts by weight: nearshore mud slurry: 120-140 parts, based on the weight of mud slurry with a water content of 60%-110%; ordinary silicate cement: 6-10 parts; S95 grade mineral powder: 4-15 parts; Cellulose ether: 0.03~0.06 parts; Sodium sulfate: 0.5~0.8 parts; Polycarboxylate superplasticizer: 0.02~0.05 parts; The nearshore mudflat silt is natural silt collected from the nearshore mudflats of the sea area where the offshore wind farm is located. It has a salt content of about 1% to 3% and an organic matter content of ≤3%.

2. The scour-resistant fluidized solidified soil material for offshore wind turbine pile foundations according to claim 1, characterized in that, The cellulose ether is hydroxypropyl methylcellulose ether with a viscosity specification of 100,000 to 200,000 mPa·s.

3. The scour-resistant fluidized solidified soil material for offshore wind turbine pile foundations according to claim 1, characterized in that, The sodium sulfate is industrial anhydrous sodium sulfate with a purity of ≥98%.

4. The scour-resistant fluidized solidified soil material for offshore wind power pile foundations according to claim 1, characterized in that, The polycarboxylate superplasticizer is in powder or liquid form, with a water reduction rate ≥25%.

5. The scour-resistant fluidized solidified soil material for offshore wind turbine pile foundations according to claim 1, characterized in that, The initial fluidity of the solidified fluid is controlled at 180~250mm, the unconfined compressive strength underwater after 28 days of hardening is ≥0.4MPa, and the cement loss rate during underwater pouring is ≤5%.

6. A method for preparing scour-resistant fluidized solidified soil material for offshore wind turbine pile foundations, characterized in that, The method includes the following steps: S1, silt pretreatment: near-shore mudflat silt is sieved to remove impurities, and the moisture content is tested and adjusted to 60%~110% to obtain silt slurry for use. S2, ordinary silicate cement, S95 grade mineral powder, sodium sulfate and polycarboxylate superplasticizer are premixed evenly in dry powder state to obtain dry-mixed cementitious material; S3, dissolve cellulose ether and polycarboxylate superplasticizer in part of the mixing water to prepare an admixture solution; S4. Add the sludge slurry from step S1 and the dry-mixed cementitious material from step S2 into the mixing device, and add the additive solution from step S3 while stirring. Continue stirring for 2 to 5 minutes until a uniform flow state is reached, and the fluidized solidified soil material is obtained.

7. Application of scour-resistant fluidized solidified soil material for offshore wind turbine pile foundations, characterized in that... The prepared fluidized solidified soil material is pumped or transported to the scour pit around the pile foundation by means of a conduit. Relying on its high fluidity and self-leveling properties, it fills the entire pit and solidifies directly underwater to form an integral anti-scour protective layer that is tightly bonded to the pile foundation and the original seabed.

8. The application of the anti-scour fluidized solidified soil material for offshore wind power pile foundations according to claim 7, characterized in that, During construction, an underwater guide pipe method is used, with the guide pipe outlet always buried at least 1m below the surface of the fluidized solidified soil to prevent water washing and dispersion. After solidification, a slope protection structure is formed with the top surface slightly higher than the original seabed surface.

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