A freezing-proof grouting construction method for the first section of a wind power mixed tower and a fan foundation in a low-temperature environment

Abstract

The present application relates to a kind of frost-proof grouting construction methods of wind power mixed tower first section and fan foundation under low temperature environment, discard traditional whole warm tent erection, using raw material preheating, grouting base preheating, insulation during mixing process, whole-process temperature control system of layered insulation after pouring, through electric heating water tank temperature control mixing water, preheating insulation vertical stirring bin, grouting groove circumferential electric heating base deicing preheating, cooperate with grouting after moisturizing, electric heating heating, layered protection and maintenance of insulation cotton quilt, realize conventional cement-based grouting material stable mixing, pouring and hydration hardening under minus low temperature environment, without open fire heating, construction is safe, environmental protection, process is simple, construction period is short, the equipment and auxiliary materials used can be recycled, greatly reduce construction cost;Grouting material is in positive temperature environment from mixing to maintenance molding whole process, effectively prevent slurry freezing, hydration stagnation, cracking and other quality defects, ensure that grouting body strength is uniform and stable, load transmission is reliable.

Description

Technical Field

[0001] This invention relates to the field of secondary grouting construction technology for wind turbine tower foundations, specifically to a method for antifreeze grouting construction of the first section of a wind turbine hybrid tower and the wind turbine foundation under low-temperature conditions. Background Technology

[0002] With the rapid development of the wind power industry, wind power projects are increasingly being built in low-temperature regions such as high latitudes and high altitudes. In wind turbine hybrid tower structures, the secondary grouting between the first section of the tower and the wind turbine foundation is a crucial process connecting the upper tower structure with the lower concrete foundation. Its construction quality directly determines the reliability of load transfer between the tower and the foundation, thus affecting the structural safety and operational life of the entire wind turbine unit.

[0003] Secondary grouting materials typically employ high-strength, early-strength cement-based grouting materials, characterized by self-leveling, early strength, and high strength. However, these materials are highly sensitive to ambient temperature during construction. The hydration reaction rate of the grouting material is closely related to ambient temperature, with the standard construction temperature range usually between 5℃ and 35℃. However, in northern, northwestern, and northeastern my country, the winter construction period can last 3 to 6 months, with ambient temperatures often below 0℃, posing a significant challenge to secondary grouting operations in low-temperature environments.

[0004] Currently, grouting construction in low-temperature environments falls into two categories: one is using low-temperature grouting materials; the other is using a heated shed insulation method. However, both methods have significant drawbacks in practical engineering applications. 1. Limited application of low-temperature grouting materials: Although special low-temperature grouting materials can be used in sub-zero temperature environments, they have problems such as high price and relatively low technical maturity. In addition, the performance of products from different manufacturers varies greatly, and the quality stability is difficult to guarantee, resulting in poor economic efficiency for large-scale engineering applications.

[0005] 2. The traditional heated shed method has high construction costs and causes significant pollution: The traditional heated shed method requires the construction of an overall insulated shed in the grouting area, using coal-fired or oil-fired heaters. This not only results in a long construction period and high material and labor costs, but also poses a safety hazard due to open flames. The combustion of coal produces a large amount of smoke and CO2, polluting the environment and endangering the health of construction workers.

[0006] 3. The quality of conventional grouting materials cannot be guaranteed in low-temperature construction: When conventional grouting materials are used directly in environments at 0℃ and below, the mixing water is prone to freezing, the self-leveling and self-compacting properties of the grout fail, the fluidity of the grouting material decreases significantly, and self-compacting pouring cannot be achieved; low temperature greatly inhibits the cement hydration reaction, the early strength growth stops, and the expansion of water when it freezes will directly crack the grouting body, the strength cannot reach the design standard, and a permanent structural safety hazard is formed.

[0007] To address the challenge of achieving high-quality secondary grouting between the first section of a wind turbine hybrid tower and the wind turbine foundation in low-temperature environments using conventional grouting materials, while ensuring grouting quality and structural safety, and significantly reducing construction costs, simplifying construction processes, and shortening the construction period, this invention proposes an antifreeze grouting construction method for the first section of a wind turbine hybrid tower and the wind turbine foundation in low-temperature environments. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for antifreeze grouting construction of the first section of the wind turbine hybrid tower and the wind turbine foundation in low-temperature environments. The method adopts a full-process electric heat tracing temperature control system that includes preheating of raw materials, preheating of the grouting base surface, insulation during the mixing process, and layered insulation after pouring. It eliminates the need to build an overall insulation shed and can complete high-quality grouting construction using conventional grouting materials in low-temperature environments.

[0009] The technical problem solved by this invention is achieved through the following technical solution: A method for antifreeze grouting construction of the first section of a wind turbine hybrid tower and the wind turbine foundation under low-temperature conditions includes the following steps: Step 1: Construction preparation and raw material preheating: 1) Preheating of grouting material: 24-48 hours before grouting, the cement-based grouting material is stored in a closed heated room for preheating and storage. The heating equipment is continuously controlled to preheat the material. At the same time, the construction materials are checked and inventoried: electric heating tape, electric blanket, plastic film, thermal insulation quilt, vertical mixing chamber, electric heating water tank, and infrared thermometer. 2) Temperature control and heating of mixing water: The mixing water is heated using an electric heating water tank; 3) Preheating and insulation of the mixing chamber: Cover the outer wall of the vertical mixing chamber with an electric heating blanket and fix it in place; turn on the preheating before the actual mixing to keep the chamber at a positive temperature throughout the process; Step 2: Preheating of the grouting base and the first section of the tower: 1) Circumferential laying of electric heat tracing: The first section of the wind turbine tower is hoisted into the grouting trench of the wind turbine foundation. After the elevation and verticality are corrected and temporarily fixed, the water, scum and frost inside the grouting trench are removed. Electric heat tracing tape is laid along the grouting trench area on the inner and outer sides of the section. The electric heat tracing tape is laid evenly along the circumference of the section and is fixed tightly to the foundation concrete surface and the side wall of the section. 2) Base surface heating and de-icing preheating: Before grouting, the base surface of the grouting tank and the tower tube segments are preheated by electric heating tape, so that the grouting contact surface is raised to a positive temperature range before entering the grouting process; Step 3: Grouting material mixing and pouring: 1) Feeding and mixing: Add metered hot water to the preheated vertical mixing chamber, add the preheated grouting material and mix at the same time. After the grouting material is completely wetted, mix at low speed for at least 3 minutes, with a mixing speed of 400~600 rpm, until the grout has a uniform consistency, no large air bubbles, no dry powder lumps, and no agglomerates. 2) Static air release of grout: After mixing, let it stand for 1 to 1.5 minutes to release the air trapped in the mixing; at the same time, monitor the temperature of the grout exiting the machine, and only after the index meets the standard can it be transported to the pouring point; 3) Gravity-driven continuous grouting: Grout is injected continuously and at a uniform speed from one side of the grouting tank using a guide channel, and the grout cavity is naturally filled by the self-leveling properties of the grout. Step 4: Post-pouring insulation and curing: 1) Surface leveling and finishing: After the grouting is completed, a special screed is used to scrape and compact the upper surface of the grout body to meet the structural flatness acceptance standard. 2) Laying of the moisture-retaining layer: A plastic film is laid on the surface of the grouting body. The overlaps of the plastic film are compacted and sealed, and the edges are sealed with heavy objects to form a sealed moisture-retaining layer. 3) Heating layer layout: On the outside of the plastic film, electric heating tape is wrapped around the inside and outside of the tower tube segments to form a heating layer. A reasonable gap is reserved between the electric heating tape and the surface of the grouting body. After the layout is completed, the heating tape is continuously powered on for curing to maintain the grouting body in a suitable positive temperature range for hydration. 4) Insulation layer covering: The outer layer of the electric heating cable is wrapped with an insulation quilt, the joints of the insulation layer are tightly overlapped, and the corners are compacted and sealed to form an insulation layer. During the curing period, the electric heating is kept running continuously, and a dedicated person conducts regular inspections during the curing period, and monitors the surface temperature of the grouting body through an infrared thermometer. After the grouting material reaches the design requirements of the subsequent tower installation process, the insulation quilt, the electric heating cable layer, and the plastic film moisture-retaining layer are removed in sequence from the outside to the inside. Furthermore, the preheating temperature of the enclosed heating room is 10-20℃, the mixing heating water temperature is 30-50℃, and the preheating temperature of the mixing chamber is ≥8℃; after the base surface is preheated, the minimum temperature of the grouting contact surface is ≥5℃, and the temperature of the grouting material exiting the machine is controlled at 10-25℃.

[0010] Furthermore, in step 4, during the post-pouring insulation and curing process, the electric heating temperature control range is 5–20℃, and the temperature difference between the inside and outside of the grout body during curing is ≤10℃.

[0011] Furthermore, the electric heating cables, electric blankets, thermal insulation quilts, vertical mixing chambers, electric heating water tanks, and infrared thermometers used in the construction are all recycled after construction and can be reused for grouting operations of multiple wind turbine units.

[0012] The advantages and positive effects of this invention are: 1. This invention adopts a full-process electric heating temperature control system, which includes preheating of raw materials, preheating of the grouting base surface, insulation during the mixing process, and layered insulation after pouring. This system enables conventional cement-based grouting materials to hydrate and harden normally in low-temperature environments, eliminating the need to purchase expensive low-temperature special grouting materials and reducing material costs. At the same time, conventional grouting materials are technically mature, have stable quality, and are widely used in engineering, avoiding the risks of immature technology and large quality fluctuations in low-temperature grouting materials. This ensures greater technical reliability, and the strength of the grouting entity meets the long-term operational safety requirements of high-altitude and cold-weather wind power structures.

[0013] 2. Compared with the traditional greenhouse method, which requires the erection of a large amount of scaffolding, insulation sheds and heating equipment, this invention adopts a combination of electric heating tape, insulation quilt and electric blanket for insulation. The materials are lightweight and easy to install. No large equipment is required. On-site construction workers of 2 to 3 people can complete the setup. The construction preparation time is shortened from 2 to 3 days of the greenhouse method to half a day. The total construction period of grouting for a single wind turbine foundation is significantly shortened. The process is simple and the construction efficiency is high.

[0014] 3. This invention forms a complete temperature protection system from raw material preheating, base surface preheating, heat preservation during mixing, to layered heat preservation after pouring, ensuring that the grout is in a positive temperature environment throughout the entire process from mixing to strength formation, avoiding the risk of early freezing; electric heating is uniform and temperature is controllable, the internal temperature difference of the grout is small, the strength development is stable, and the quality of the solid is guaranteed.

[0015] 4. This invention uses electric heating throughout the process, eliminating the open flame heat source of coal / oil combustion, thus eliminating the safety hazards of fire and carbon monoxide poisoning; there is no emission of pollutants such as smoke and carbon dioxide, which meets the requirements of green construction and dust environmental protection control, and greatly improves the outdoor construction working environment in winter.

[0016] 5. The electric heating tape, electric blanket, thermal insulation quilt, vertical mixing chamber, electric heating water tank, and infrared thermometer gun used in the construction of this invention are uniformly recycled after construction and can be reused for grouting operations of multiple wind turbine units. The amortization cost of auxiliary materials for a single construction is much lower than that of disposable warm shed construction materials. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of the antifreeze grouting construction method for the first section of the wind power hybrid tower and the wind turbine foundation under low temperature conditions according to the present invention. Detailed Implementation

[0018] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0019] Selecting a winter construction scenario in a high-altitude, cold wind farm in Northeast my country, with an ambient temperature of -12℃, this study employs an antifreeze grouting method for the first section of the wind turbine hybrid tower foundation and the wind turbine base under low-temperature conditions. The secondary grouting of the first section foundation comprises four continuous processes: construction preparation and raw material preheating, preheating of the grouting base surface and the first section of the tower, grout mixing and pouring, and post-pouring thermal insulation and curing. The specific steps are as follows: like Figure 1 As shown, Step 1, Construction Preparation and Raw Material Preheating: 1) Preheating of grouting material: 48 hours before grouting, SikaGrout.-3250 CN cement-based grouting material is stored in a closed heated room for preheating and storage. The heating equipment continuously controls the temperature to 15°C to ensure that the grouting material maintains a positive temperature and prevents low-temperature clumping and reduction of gelling activity. At the same time, the construction materials are checked and inspected: electric heating tape, electric blanket, plastic film, thermal insulation quilt, vertical mixing chamber, electric heating water tank, infrared thermometer to ensure that the materials are undamaged and the equipment is operating normally.

[0020] 2) Temperature control and heating of mixing water: The mixing water is heated to 42℃ by an electric heating water tank. A dedicated person monitors and controls the water temperature in real time to avoid false setting or flash setting of the grout caused by excessive water temperature. Hot water is strictly measured according to the water-to-material ratio (water:powder = 2.75:25) specified in the grout instructions. A small amount of hot water is reserved for fine-tuning the fluidity of the grout on site.

[0021] 3) Preheating and insulation of the mixing chamber: Cover the outer wall of the vertical mixing chamber with an electric heating blanket and fix it in place; preheat to 10°C 2 hours before formal mixing to keep the chamber at a positive temperature throughout the process, and prevent the low-temperature chamber from rapidly absorbing the heat of the slurry, causing a sudden drop in slurry temperature and rapid loss of fluidity.

[0022] Step 2: Preheating of the grouting base and the first section of the tower: 1) Circumferential laying of electric heat tracing: The first section of the wind turbine tower is hoisted into the grouting trench of the wind turbine foundation. After the elevation and verticality are corrected and temporarily fixed, the water, scum and frost inside the grouting trench are removed. Electric heat tracing tape is laid along the inner and outer sides of the grouting trench area of ​​the section. The electric heat tracing tape is laid evenly along the circumference of the section and is fixed tightly to the foundation concrete surface and the side wall of the section to ensure that the preheating range completely covers the grouting contact surface.

[0023] 2) Preheating and de-icing of the base surface: Before grouting, the base surface of the grouting trench and the tower tube segments are preheated for 3 hours by electric heating tape, so that the grouting contact surface is raised to 7°C, completely melting the ice and frost on the base surface, avoiding the rapid absorption of heat from the grout by the low-temperature base surface, which would cause the grouting material to freeze early and hinder the hydration reaction; the base surface temperature is collected at regular intervals throughout the process, and the grouting process begins after confirming that there is no ice or frost residue and the contact surface is at a positive temperature throughout the process.

[0024] Step 3: Grouting material mixing and pouring: 1) Feeding and mixing: Add metered hot water to the preheated vertical mixing chamber, add the preheated grout and mix simultaneously. After the grout is completely wetted, mix at low speed for at least 3 minutes at a mixing speed of 400~600 rpm until the grout has a uniform consistency, no large air bubbles, no dry powder lumps, and no agglomerates.

[0025] 2) Static air release of grout: After mixing, let it stand for 1.5 minutes to release the air trapped by mixing; at the same time, check the temperature of the grout exiting the machine (10-25℃). Only after the index meets the standard can it be transported to the pouring point.

[0026] 3) Gravity self-flowing continuous grouting: The grout is injected into the grouting tank at a uniform speed and continuously from one side using a guide channel, and the grouting cavity is naturally filled by the self-leveling properties of the grout.

[0027] Step 4: Post-pouring insulation and curing: 1) Surface leveling and finishing: After the grouting is completed, a special scraper is used to scrape and compact the upper surface of the grout body to meet the acceptance standards for structural flatness.

[0028] 2) Laying of the moisture-retaining layer: A plastic film is laid on the surface of the grout. The overlap of the plastic film is compacted and sealed, and the edges are sealed with heavy objects to form a sealed moisture-retaining layer, which locks in the moisture inside the grout and prevents the rapid loss of moisture on the surface of the grout from causing drying shrinkage cracks, thus ensuring the sealing and moisture-retaining effect.

[0029] 3) Heating layer layout: On the outside of the plastic film, electric heating tape is wrapped around the inside and outside of the tower tube to form a heating layer. A reasonable gap is reserved between the electric heating tape and the surface of the grout. After the layout is completed, the heating tape is continuously powered on for curing to stably maintain the appropriate positive temperature range for hydration of the grout.

[0030] 4) Insulation Layer Covering: The outer layer of the electric heating cable is wrapped with an insulation blanket, and the seams of the insulation layer are tightly overlapped, with the corners compacted and sealed to form an insulation layer, minimizing heat loss. During the curing period, the electric heating is kept running continuously at a controlled temperature of 12℃. A designated person conducts inspections every 2 hours during the curing period, monitoring the surface temperature of the grouting body using an infrared thermometer to ensure the grouting body is kept in a stable positive temperature curing environment throughout the process. After 72 hours of curing, the grouting material's solid strength is tested to ensure it reaches 100% of the design strength for subsequent tower installation procedures, and the temperature difference between the inside and outside of the grouting body is ≤10℃. The insulation blanket, heating layer, and plastic film moisture-retaining layer are removed sequentially from the outside in. All electric heating cables, electric blankets, insulation blankets, vertical mixing chambers, electric heating water tanks, and infrared thermometers used in the construction are recycled after construction and can be reused for grouting operations of multiple wind turbine units.

[0031] Compared with traditional greenhouse construction methods, this method requires only 4 hours of preparation time, while the greenhouse method requires 2.5 days; the entire process is powered by electricity with no open flames, exhaust fumes, or dust; there is no need to purchase expensive low-temperature special grouting materials, and auxiliary materials can be reused, reducing the overall construction cost of grouting with a single fan by 42%; the grouting body is free from freezing damage throughout the process, with uniform and stable strength, and no shrinkage or frost heave cracks.

[0032] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A method for antifreeze grouting construction of the first section of a wind turbine hybrid tower and the wind turbine foundation under low-temperature conditions, characterized in that: Includes the following steps: Step 1: Construction preparation and raw material preheating: 1) Preheating of grouting material: 24-48 hours before grouting, the cement-based grouting material is stored in a closed heated room for preheating and storage. The heating equipment is continuously controlled to preheat the material. At the same time, the construction materials are checked and inventoried: electric heating tape, electric blanket, plastic film, thermal insulation quilt, vertical mixing chamber, electric heating water tank, and infrared thermometer. 2) Temperature control and heating of mixing water: The mixing water is heated using an electric heating water tank; 3) Preheating and insulation of the mixing chamber: Cover the outer wall of the vertical mixing chamber with an electric heating blanket and fix it in place; turn on the preheating before the actual mixing to keep the chamber at a positive temperature throughout the process; Step 2: Preheating of the grouting base and the first section of the tower: 1) Circumferential laying of electric heat tracing: The first section of the wind turbine tower is hoisted into the grouting trench of the wind turbine foundation. After the elevation and verticality are corrected and temporarily fixed, the water, scum and frost inside the grouting trench are removed. Electric heat tracing tape is laid along the grouting trench area on the inner and outer sides of the section. The electric heat tracing tape is laid evenly along the circumference of the section and is fixed tightly to the foundation concrete surface and the side wall of the section. 2) Base surface heating and de-icing preheating: Before grouting, the base surface of the grouting tank and the tower tube segments are preheated by electric heating tape, so that the grouting contact surface is raised to a positive temperature range before entering the grouting process; Step 3: Grouting material mixing and pouring: 1) Feeding and mixing: Add metered hot water to the preheated vertical mixing chamber, add the preheated grouting material and mix at the same time. After the grouting material is completely wetted, mix at low speed for at least 3 minutes, with a mixing speed of 400~600 rpm, until the grout has a uniform consistency, no large air bubbles, no dry powder lumps, and no agglomerates. 2) Static air release of grout: After mixing, let it stand for 1 to 1.5 minutes to release the air trapped in the mixing; at the same time, monitor the temperature of the grout exiting the machine, and only after the index meets the standard can it be transported to the pouring point; 3) Gravity-driven continuous grouting: Grout is injected continuously and at a uniform speed from one side of the grouting tank using a guide channel, and the grout cavity is naturally filled by the self-leveling properties of the grout. Step 4: Post-pouring insulation and curing: 1) Surface leveling and finishing: After the grouting is completed, a special screed is used to scrape and compact the upper surface of the grout body to meet the structural flatness acceptance standard. 2) Laying of the moisture-retaining layer: A plastic film is laid on the surface of the grouting body. The overlaps of the plastic film are compacted and sealed, and the edges are sealed with heavy objects to form a sealed moisture-retaining layer. 3) Heating layer layout: On the outside of the plastic film, electric heating tape is wrapped around the inside and outside of the tower tube segments to form a heating layer. A reasonable gap is reserved between the electric heating tape and the surface of the grouting body. After the layout is completed, the heating tape is continuously powered on for curing to maintain the grouting body in a suitable positive temperature range for hydration. 4) Insulation layer coverage: The outer layer of the electric heating cable is wrapped with an insulation quilt, the seams of the insulation layer are tightly overlapped, and the corners are compacted and sealed to form an insulation layer. During the curing period, the electric heating is kept running continuously, and a dedicated person conducts regular inspections during the curing period, and monitors the surface temperature of the grouting body through an infrared thermometer. After the grouting material reaches the design requirements of the subsequent tower installation process, the insulation quilt, the heating layer of the electric heating cable, and the moisture-retaining layer of the plastic film are removed in sequence from the outside to the inside.

2. The method for antifreeze grouting construction of the first section of the wind turbine hybrid tower and the wind turbine foundation under low temperature environment as described in claim 1, characterized in that: The preheating temperature of the enclosed heating room is 10-20℃, the mixing heating water temperature is 30-50℃, and the preheating temperature of the mixing chamber is ≥8℃. After the base surface is preheated, the minimum temperature of the grouting contact surface is ≥5℃, and the temperature of the grouting material exiting the machine is controlled at 10-25℃.

3. The method for antifreeze grouting construction of the first section of the wind turbine hybrid tower and the wind turbine foundation under low temperature environment as described in claim 1, characterized in that: In step 4, during the post-pouring insulation and curing process, the electric heating temperature control range is 5-20℃, and the temperature difference between the inside and outside of the grout body during curing is ≤10℃.

4. The method for antifreeze grouting construction of the first section of the wind turbine hybrid tower and the wind turbine foundation under low temperature environment as described in claim 1, characterized in that: The electric heating cables, electric blankets, thermal insulation quilts, vertical mixing chambers, electric heating water tanks, and infrared thermometers used in the construction are all recycled after construction and can be reused for grouting operations of multiple wind turbine units.

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