Temperature monitoring and control method in large-volume concrete pouring process of fan foundation

Abstract

The invention discloses a temperature monitoring and control method in a large-volume concrete pouring process of a fan foundation, which belongs to the technical field of fan foundation construction and comprises the following steps: S10, arranging temperature measuring points in the foundation: arranging at least two temperature measuring points along the radial direction of the foundation; s20, test element installation: arranging a first test element for monitoring the atmospheric temperature on the outer side of the foundation; correspondingly installing a second test element at each temperature measurement point in the foundation; s30, constructing a temperature change model; and S40, inputting real-time monitoring data of each monitoring point in the pouring process into the temperature change model, wherein the temperature change model gives an implementation regulation and control scheme. According to the method, the temperature change of mass concrete in the pouring process can be monitored in real time, an accurate regulation and control scheme is given, real-time and accurate monitoring and regulation and control can be achieved, and the construction quality requirement of a wind power foundation is met.

Description

Technical Field

[0001] This invention belongs to the field of wind turbine foundation construction technology, and more specifically relates to a method for temperature monitoring and control during the pouring of large-volume concrete for wind turbine foundations. Background Technology

[0002] Wind power is a clean energy source, characterized by its renewability, lack of pollution, high energy output, and promising future. Vigorously developing clean energy is a strategic choice for countries worldwide. With continuous technological advancements, the single-unit capacity of wind turbines is increasing, leading to larger wind turbine foundations. The massive volume of concrete in wind turbine foundations causes a significant heat release during cement hydration, resulting in a rapid rise in internal concrete temperature. Simultaneously, the concrete surface dissipates heat more quickly, creating a large temperature gradient and generating thermal stress. When this thermal stress exceeds the tensile strength of the concrete, cracks will form, severely impacting the strength, durability, and waterproofing performance of the concrete structure.

[0003] The temperature monitoring and control of large-volume concrete for existing wind turbine foundations mostly rely on manual periodic measurements, which is not only inefficient but also makes it difficult to achieve real-time and accurate monitoring and control, thus failing to meet the construction requirements of wind power foundations. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for temperature monitoring and control during the pouring of large-volume concrete for wind turbine foundations includes the following steps: S10. Arrangement of internal temperature measurement points of the foundation At least two temperature measurement points are arranged along the radial direction of the foundation, and one temperature measurement line is arranged along the height direction at each temperature measurement point; the temperature measurement points on the surface and bottom of the foundation are 40-100mm away from the surface and bottom of the foundation, and multiple temperature measurement points are evenly arranged along the thickness direction on each temperature measurement axis. S20, Install test components A first testing element for monitoring atmospheric temperature is installed on the outside of the foundation; a second testing element is installed at each temperature measuring point inside the foundation; the second testing element should be firmly fixed and isolated from the structural steel bars and the metal body of the fixing frame. S30. Construct a temperature change model Based on the design requirements of the wind turbine foundation, the concrete mix ratio, the on-site construction conditions, and the temperature change pattern during the concrete pouring process, a temperature change model is constructed based on a convolutional neural network. S40, Implementing Regulation The real-time monitoring data of each monitoring point during the pouring process is input into the temperature change model, which provides an implementation control scheme. The implementation control scheme serves as the basis for parameter control during the pouring process.

[0005] Furthermore, the implementation of the control plan includes: 1) Concrete discharge temperature; adjust the concrete pouring temperature within a suitable range. 2) During the heating phase, appropriate heat dissipation should be carried out to reduce the peak temperature rise; when the heating rate slows down, insulation measures should be added in a timely manner to prevent the surface temperature from dropping rapidly. 3) During the cooling phase, adjust the insulation layer thickness based on temperature monitoring results; 4) Adjust the thickness of the poured layers and the inter-layer covering interval, and adjust the concrete discharge speed at the same time; 5) Adjust the pouring rate; 6) Adjust the concrete material mix ratio.

[0006] Furthermore, the temperature requirements during the concrete pouring process are as follows: Temperature difference between inside and outside: The temperature difference between the inside and outside of the concrete should not exceed 25℃; Cooling rate: Control the concrete temperature drop to no more than 2℃ / day.

[0007] Furthermore, based on the design requirements of the wind turbine foundation, concrete mix proportion, on-site construction conditions, pouring rate, pouring time, layer thickness, and temperature changes in previous concrete pouring processes, and based on thermal calculations or simulations to predict the temperature rise curve and temperature field distribution of the concrete, training samples are constructed. The temperature change model based on the convolutional neural network is then trained using the training samples.

[0008] Furthermore, the temperature change model includes a cement hydration heat calculation model, a concrete adiabatic temperature rise model, a concrete mixing temperature calculation model, a concrete center temperature calculation model, and a concrete surface temperature calculation model at 200mm below the surface. The calculation model for the heat of hydration of cement is as follows: Q0 = 4 / (7 / Q7 - 3 / Q3) Where: Q3---cumulative heat of hydration at age 3d (kJ / kg); Q7---Cumulative heat of hydration at 7 days of age (kJ / kg); Q0 --- Total heat of hydration of cement (kJ / kg); The total heat of hydration of cementitious materials should be calculated using the following formula after the dosages of cement, admixtures, and additives are determined: Q = kQ0 Q----Total heat of hydration of cementitious materials (kJ / kg) k----Adjustment coefficient for heat of hydration of admixtures with different dosages; The concrete adiabatic temperature rise model is as follows: T(t) = WQ(1-e -mt) / Cρ Where: T(t) --- adiabatic temperature rise (°C) of concrete at age t; W --- Cementitious material usage per cubic meter of concrete (kg / m3) C --- Specific heat capacity of concrete; ρ --- the mass density of concrete; t---Concrete age (d); m---Corresponding coefficient of single-unit cementitious material related to cement type, dosage and pouring temperature; e is a constant, taken as 2.718; The concrete mixing temperature calculation model is as follows: T0 =∑Ti×W×C / ∑W×C Where: T0---concrete mixing temperature (°C); Ti --- Initial temperature (°C) of each component of concrete; concrete temperature. W — Mass of various materials per cubic meter of concrete (kg); C—Specific heat capacity of concrete components (kJ / kg.K); The calculation model for the concrete center temperature is as follows: T1(t) — Tj + Th·ξ(τ) Where: T1(t) — Calculated temperature at the center of concrete at age t (°C); Tj — Concrete pouring temperature (°C); ξ(τ)——Coefficient of temperature drop at age τ; The calculation model for the concrete surface temperature at 200mm below the surface is as follows: The thickness of the thermal insulation material is given by the formula: δ = (0.5hλ) i (T) s -T q )) / (λ0(T max -T b ))×K b Where: δ——thickness of the insulation layer on the concrete surface (m); λ0 — Thermal conductivity of concrete [W / (m²] K)]; λ i — Thermal conductivity of insulation materials [W / (m)] K)]; T s — Surface temperature of the concrete pouring body (°C); T q —Average atmospheric temperature (°C) when the concrete reaches its maximum temperature (3-5 days after pouring); T max —The highest temperature (°C) inside the concrete casting; h—actual thickness of the concrete structure (m); T s —T q —Take 15℃-20℃; T max —T b —Take 20℃-25℃; K b — Correction value for heat transfer coefficient.

[0009] Furthermore, the first test element and the second test element shall meet the following requirements: 1) Under 25℃ conditions, the temperature measurement error should not exceed 0.3℃; 2) The temperature test range should be -30℃ to 20℃; 3) The test resolution of the strain testing element should not be greater than 5µε; 4) The strain test range should meet the requirement of 1000µε-1000µε; 5) The insulation resistance of the test element should be greater than 500MΩ.

[0010] Furthermore, the requirements for installing the first test element and the second test element in step S20 are as follows: 1) The test element should be securely fixed and isolated from the structural steel reinforcement and the metal body of the fixing frame; 2) Test component leads are centrally arranged, labeled and protected along the routing direction; 3) Protective measures should be taken around the test element. The temperature test element and its leads should not be directly impacted or touched during feeding and vibration.

[0011] Furthermore, after the concrete foundation of the wind turbine has set, the surface is moistened with water and covered with a layer of plastic film and a layer of felt in a timely manner. Depending on the actual temperature difference, it is decided whether to add another layer of felt. During the insulation period, the concrete is frequently checked to see if it needs to be replenished with water. A layer of felt is used to cover the sides of the concrete to reduce air convection, thereby achieving the purpose of heat preservation and control of the concrete sides.

[0012] Compared with the prior art, the present invention has the following beneficial effects: The temperature monitoring and control method for the large-volume concrete pouring process of wind turbine foundations provided by this invention can monitor the temperature changes of large-volume concrete in real time during the pouring process and provide a precise control scheme. It can achieve real-time and accurate monitoring and control, thus meeting the construction quality requirements of wind power foundations. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0014] Figure 1 This is a layout diagram of the temperature control monitoring points. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1

[0017] This embodiment uses the construction of the wind turbine foundation for a single 6.25MW wind turbine generator set as an example for illustration.

[0018] refer to Figure 1 A method for temperature monitoring and control during the pouring of large-volume concrete for wind turbine foundations, comprising the following steps: S10. Arrangement of internal temperature measurement points of the foundation At least two temperature measurement points should be arranged along the radial direction of the foundation, and one temperature measurement line should be arranged along the height direction at each temperature measurement point; the temperature measurement points on the surface and bottom of the foundation should be 40-100mm away from the surface and bottom of the foundation, and 3-5 temperature measurement points should be evenly arranged along the thickness direction on each temperature measurement axis. S20, Install test components A first testing element for monitoring atmospheric temperature is installed on the outside of the foundation; a second testing element is installed at each temperature measurement point inside the foundation; the second testing element should be firmly fixed and isolated from the structural steel bars and the metal body of the fixing frame. S30. Construct a temperature change model Based on the design requirements of the wind turbine foundation, the concrete mix ratio, the on-site construction conditions, and the temperature change pattern during the concrete pouring process, a temperature change model is constructed based on a convolutional neural network. S40, Implementing Regulation Real-time monitoring data from each monitoring point during the pouring process are input into the temperature change model. The temperature change model then provides an implementation and control plan, which serves as the basis for parameter control during the pouring process.

[0019] In this embodiment, the control scheme includes: 1) Concrete discharge temperature; adjust the concrete pouring temperature within a suitable range. 2) During the heating phase, appropriate heat dissipation should be carried out to reduce the peak temperature rise; when the heating rate slows down, insulation measures should be added in a timely manner to prevent the surface temperature from dropping rapidly. 3) During the cooling phase, adjust the insulation layer thickness based on temperature monitoring results; 4) Adjust the thickness of the poured layers and the inter-layer covering interval, and adjust the concrete discharge speed at the same time; 5) Adjust the pouring rate; 6) Adjust the concrete material mix ratio.

[0020] In this embodiment, the temperature requirement during the concrete pouring process is as follows: Temperature difference between inside and outside: The temperature difference between the inside and outside of the concrete should not exceed 25℃; Cooling rate: Control the concrete temperature drop to no more than 2℃ / day.

[0021] In this embodiment, training samples are constructed based on the design requirements of the wind turbine foundation, concrete mix proportion, on-site construction conditions, pouring rate, pouring time, layer thickness, and temperature changes in the past concrete pouring process, and based on thermal calculations or simulations to predict the temperature rise curve and temperature field distribution of the concrete. The training samples are then used to train the temperature change model based on the convolutional neural network.

[0022] The convolutional neural network includes an input layer, convolutional layers, and pooling layers. It has 16 convolutional layers and a kernel size of 3. The system consists of 3 convolutional layers and 5 max-pooling layers. The training samples comprise 80% training samples and 20% test training samples.

[0023] In this embodiment, the principle of arranging the temperature measurement points is to comprehensively, accurately, and representatively reflect the internal temperature of the foundation. Specifically, two temperature measurement points are arranged radially along the foundation, and one temperature measurement line is arranged along the height direction at each temperature measurement point. The surface and bottom temperature measurement points are 50mm away from the surface and bottom of the foundation, and 3 to 5 temperature measurement points are evenly arranged along the thickness direction on each temperature measurement axis.

[0024] In this embodiment, the temperature requirement during the concrete pouring process is as follows: Temperature difference between inside and outside: The temperature difference between the inside and outside of the concrete should not exceed 25℃; Cooling rate: Control the concrete temperature drop to no more than 2℃ / day.

[0025] After the concrete is poured, the temperature should be measured every 2 hours for the first 72 hours, every 4 hours after 72 hours, and every 6 hours from 7 to 14 days, until the temperature stabilizes.

[0026] In this embodiment, the temperature change model includes a cement hydration heat calculation model, a concrete adiabatic temperature rise model, a concrete mixing temperature calculation model, a concrete center temperature calculation model, and a concrete surface temperature calculation model 200mm below the surface. This embodiment is calculated based on the foundation concrete grade C40, using ordinary Portland 42.5 cement with a dosage of 318 kg / m³. 3 The calculation is as follows: The calculation model for the heat of hydration of cement is as follows: Q0=4 / (7 / Q7-3 / Q3)= 4 / (7 / 314-3 / 276) = 350.16 kJ / kg Where: Q3---cumulative heat of hydration at age 3d (kJ / kg); Q7---Cumulative heat of hydration at 7 days of age (kJ / kg); Q0 --- Total heat of hydration of cement (kJ / kg); The total heat of hydration of cementitious materials should be calculated using the following formula after the dosages of cement, admixtures, and additives are determined: Formula: Q = kQ0 = 0.95 × 350.16 = 332.65 (kJ / kg) Where: Q----Total heat of hydration of cementitious materials (kJ / kg) k----Adjustment coefficient for heat of hydration of admixtures with different dosages; The concrete adiabatic temperature rise model is as follows: T(t) = WQ(1-e -mt ) / Cρ=435×371.8×(1-2.718 -0.4×3 ) / (0.97×2400)= 32.12℃ Where: T(t) --- adiabatic temperature rise (°C) of concrete at age t; W --- Cementitious material usage per cubic meter of concrete (kg / m3) C --- Specific heat capacity of concrete, which can be taken as 0.92-1.00 [kJ / (kg·℃)]; ρ --- The mass density of concrete, which can be taken as 2400~2500 (kg / m3). t---Concrete age (d); m---Corresponding coefficient of single-unit cementitious material related to cement type, dosage and pouring temperature; e is a constant, taken as 2.718; The calculation model for concrete mixing temperature is as follows: The cement used is PO42.5, and T0 = ∑Ti×W×C / ∑W×C Where: T0---concrete mixing temperature (°C); Ti --- Initial temperature (°C) of each component of concrete; concrete temperature. W — Mass of various materials per cubic meter of concrete (kg); C—Specific heat capacity of concrete components (kJ / kg.K); Specifically, Twater = 27℃, Tcement = 25℃, Tsand = 25℃, Taggregate = 25℃; W is the mass (kg) of each material per cubic meter of concrete. For C40 concrete, Wwater = 166kg, Wcement = 318kg (admixture 141kg), Wsand = 587kg, Waggregate = 1104kg. The moisture content of sand is 3%, and the moisture content of aggregate is 1.9%; C is the specific heat capacity (kJ / kg.K) of the concrete components. Cwater = 4.2, Ccement = 0.84, Caggregate = 0.84.

[0027] The concrete mixing temperature is: T0=(27×166×4.2+25×318×0.84+25×587×97%×0.84+25×1104×98.1%×0.84) / (166×4.2+0.84×318+0.84×587+0.84×1104)=25.245℃.

[0028] Considering unfavorable outdoor temperatures, we set the air temperature at 27℃. Tj = T0+(Tq—T0)×(A1+A2+A3+A4+A5) Where: Tj — concrete pouring temperature; T0—Concrete mixing temperature; Tq—Outdoor temperature during concrete pouring and transportation; A1—Outdoor loss coefficient, A1=0.032, A2=0.00424×5—0.021, A3=0.032, A4=0.032, A5=0.003×20=0.06, ∑A1=0.156.

[0029] The concrete pouring temperature is: Tj = 25.245 + (27 - 25.245) × 0.156 = 25.52℃.

[0030] The calculation model for the center temperature of concrete is as follows: T1(t) — Tj + Th·ξ(τ) Where: T1(t) — Calculated temperature at the center of concrete at age t (°C); Tj — Concrete pouring temperature (°C); ξ(τ)——Coefficient of temperature drop at age τ; Calculated temperature at the center of concrete after 3 days: T1(t)—Tj+Th·ξ(τ)=25.52+32.12×0.57=43.83℃ Calculated temperature at the center of concrete at 6 days: T1(t)—Tj+Th·ξ(τ)=25.52+32.12×0.54=42.86℃ Calculated temperature at the center of concrete at 9 days: T1(t)—Tj+Th·ξ(τ)=25.52+32.12×0.475=40.78℃ Calculated temperature at the center of concrete at 12 days: T1(t)—Tj+Th·ξ(τ) 25.52+32.12×0.385=37.89℃ Calculated temperature at the center of concrete at 15 days: T1(t)—Tj+Th·ξ(τ)=25.52+32.12×0.295=35.00℃.

[0031] The calculation model for the concrete surface temperature 200mm below the surface is: where: δ = (0.5hλ) / (insulation material thickness) i (T) s -T q )) / (λ0(T max -T b ))×K b

[0032] Where: δ——thickness of the insulation layer on the concrete surface (m); λ0 — Thermal conductivity of concrete [W / (m²] K)], the value of steel formwork is 58; λ i — Thermal conductivity of insulation materials [W / (m)] K)], for thin plastics, the value is 0.2; T s — Surface temperature of the concrete pouring body (°C); T q —Average atmospheric temperature (°C) when the concrete reaches its maximum temperature (3-5 days after pouring); T max —The highest temperature (°C) inside the concrete casting; h—actual thickness of the concrete structure (m); T s —T q —Take 15℃-20℃; T max —T b—Take 20℃-25℃; K b —The heat transfer coefficient correction value is taken as 1.3-2.3.

[0033] Therefore, δ = (0.5 × 2 × 0.2 × 20) / (58 × 25) × 1.3 = 0.0035.

[0034] In this embodiment, the formula for calculating the total thermal resistance of the insulation layer is:

[0035] In the formula: R s —Total thermal resistance of insulation layer (m) 2 K / W);

[0036] δ i —Thickness (m) of the i-th layer of insulation material; λ i —The thermal conductivity of the i-th layer of insulation material [W / (mike)]; β μ —The heat transfer coefficient of solids in air [W / (m²)] 2 K)], wind speed 4m / s, value 76.6124; The conclusion is: R s = 0.0035÷0.2+1÷76.6124 = 0.03; The formula for calculating the overall heat transfer coefficient from the concrete surface to the insulation medium is: β s = 1 / R s Where: β s —Overall heat transfer coefficient [W / (m2)] K)]; R s —Total thermal resistance of insulation layer (m2) K / W).

[0037] It is concluded that β s = 1 ÷ 0.03 = 33.33

[0038] The formula for calculating the virtual thickness of the insulation layer equivalent to concrete is: h'=λ0 / β s Where: h' — virtual thickness of concrete (m); β s —Overall heat transfer coefficient [W / (m²)] 2 K)] Therefore, h' = 58 ÷ 33.33 = 1.74 The formula for calculating the thickness of concrete is: H = h + 2h' Where: H — calculated thickness of concrete (m); h——actual thickness of concrete (m); h' — Virtual thickness of concrete (m); Therefore, H = 4 + 1.74 × 2 = 7.48m The formula for calculating the surface temperature of concrete is: T2 (t) = T q +4h'(H-h')[T1-T q ] / H 2 In the formula: T2 (t) —Concrete surface temperature (°C); T q —The average atmospheric temperature during the construction period is taken as 25 (°C); h' — Virtual thickness of concrete (m); T1 — Concrete core temperature (°C); H — Calculated thickness of concrete (m).

[0039] Concrete surface temperature at 3 days: T2 (t) = 25 + 4 × 1.74 × (7.48 - 1.74) × (43.83 - 25) / 7.48 2 =38.45℃; Concrete surface temperature at 6 days: T2 (t) = 25 + 4 × 1.74 × (7.48 - 1.74) × (42.86 - 25) / 7.48 2 =37.75℃; Concrete surface temperature at 9 days: T2 (t) = 25 + 4 × 1.74 × (7.48 - 1.74) × (40.78 - 25) / 7.48 2 =36.27℃; Concrete surface temperature at 12 days: T2 (t) = 25 + 4 × 1.74 × (7.48 - 1.74) × (37.89 - 25) / 7.48 2 =34.20℃; Concrete surface temperature at 15 days: T2 (t)= 25 + 4 × 1.74 × (7.48 - 1.74) × (35 - 25) / 7.48 2 =32.14℃; Based on calculations of the core and surface temperatures of the concrete at 3, 6, 9, 12, and 15 days, their temperature differences are 0.69℃, 1.49℃, 2.06℃, and 2.06℃, respectively, all less than 25℃.

[0040] In this embodiment, the first test element and the second test element should meet the following requirements: 1) Under 25℃ conditions, the temperature measurement error should not exceed 0.3℃; 2) The temperature test range should be -30℃ to 20℃; 3) The test resolution of the strain testing element should not be greater than 5µε; 4) The strain test range should meet the requirement of 1000µε-1000µε; 5) The insulation resistance of the test element should be greater than 500MΩ.

[0041] In this embodiment, the requirements for installing the first test element and the second test element in step S20 are as follows: 1) The test element should be securely fixed and isolated from the structural steel reinforcement and the metal body of the fixing frame; 2) Test component leads are centrally arranged, labeled and protected along the routing direction; 3) Protective measures should be taken around the test element. The temperature test element and its leads should not be directly impacted or touched during feeding and vibration.

[0042] In this embodiment, after the concrete of the wind turbine foundation has set, the surface is moistened with water and covered with a layer of plastic film and a layer of felt in a timely manner. Depending on the actual temperature difference, it is decided whether to add another layer of felt. During the insulation period, the concrete is frequently checked to see if it needs to be replenished with water, and water is added in a timely manner if necessary. A layer of felt is used to cover the sides of the concrete to reduce air convection, so as to achieve the purpose of heat preservation and control of the concrete sides.

[0043] The technical solutions of the present invention have been fully described above. It should be noted that the specific embodiments of the present invention are not limited to the above description. All technical solutions formed by those skilled in the art based on the spirit and essence of the present invention by adopting equivalent transformations or equivalent transformations in terms of structure, method or function fall within the protection scope of the present invention.

Claims

1. A method for temperature monitoring and control during the pouring of large-volume concrete for wind turbine foundations, characterized in that, Includes the following steps: S10. Arrangement of internal temperature measurement points of the foundation At least two temperature measurement points are arranged along the radial direction of the foundation, and one temperature measurement line is arranged along the height direction at each temperature measurement point; the temperature measurement points on the surface and bottom of the foundation are 40-100mm away from the surface and bottom of the foundation, and multiple temperature measurement points are evenly arranged along the thickness direction on each temperature measurement axis. S20, Install test components A first testing element for monitoring atmospheric temperature is installed on the outside of the foundation; a second testing element is installed at each temperature measuring point inside the foundation; the second testing element should be firmly fixed and isolated from the structural steel bars and the metal body of the fixing frame. S30. Construct a temperature change model Based on the design requirements of the wind turbine foundation, the concrete mix ratio, the on-site construction conditions, and the temperature change pattern during the concrete pouring process, a temperature change model is constructed based on a convolutional neural network. S40, Implementing Regulation The real-time monitoring data of each monitoring point during the pouring process is input into the temperature change model, which provides an implementation control scheme. The implementation control scheme serves as the basis for parameter control during the pouring process.

2. The method for temperature monitoring and control during the large-volume concrete pouring process of wind turbine foundations according to claim 1, characterized in that, The implementation and control plan includes: 1) Concrete discharge temperature; adjust the concrete pouring temperature within a suitable range. 2) During the heating phase, appropriate heat dissipation should be carried out to reduce the peak temperature rise; when the heating rate slows down, insulation measures should be added in a timely manner to prevent the surface temperature from dropping rapidly. 3) During the cooling phase, adjust the insulation layer thickness based on temperature monitoring results; 4) Adjust the thickness of the poured layers and the inter-layer covering interval, and adjust the concrete discharge speed at the same time; 5) Adjust the pouring rate; 6) Adjust the concrete material mix ratio.

3. The method for temperature monitoring and control during the large-volume concrete pouring process of wind turbine foundations according to claim 2, characterized in that, The temperature requirements during concrete pouring are as follows: Temperature difference between inside and outside: The temperature difference between the inside and outside of the concrete should not exceed 25℃; Cooling rate: Control the concrete temperature drop to no more than 2℃ / day.

4. The method for temperature monitoring and control during the large-volume concrete pouring process of wind turbine foundations according to claim 3, characterized in that, Based on the design requirements of the wind turbine foundation, concrete mix proportions, on-site construction conditions, pouring rate, pouring time, layer thickness, and temperature changes in previous concrete pouring processes, and based on thermal calculations or simulations to predict the temperature rise curve and temperature field distribution of the concrete, training samples are constructed. The temperature change model based on the convolutional neural network is then trained using the training samples.

5. The method for temperature monitoring and control during the large-volume concrete pouring process of wind turbine foundations according to claim 1, characterized in that, The temperature change model includes a cement hydration heat calculation model, a concrete adiabatic temperature rise model, a concrete mixing temperature calculation model, a concrete center temperature calculation model, and a concrete surface temperature calculation model at 200mm below the surface. The calculation model for the heat of hydration of cement is as follows: Q0 = 4 / (7 / Q7 - 3 / Q3) Where: Q3---cumulative heat of hydration at age 3d (kJ / kg); Q7---Cumulative heat of hydration at 7 days of age (kJ / kg); Q0 --- Total heat of hydration of cement (kJ / kg); The total heat of hydration of cementitious materials should be calculated using the following formula after the dosages of cement, admixtures, and additives are determined: Q = kQ0 Where: Q----Total heat of hydration of cementitious materials (kJ / kg) k----Adjustment coefficient for heat of hydration of admixtures with different dosages; The concrete adiabatic temperature rise model is as follows: T(t)=WQ(1-e -mt ) / Cρ Where: T(t) --- adiabatic temperature rise (°C) of concrete at age t; W --- Cementitious material usage per cubic meter of concrete (kg / m3) C --- Specific heat capacity of concrete; ρ --- the mass density of concrete; t---Concrete age (d); m---Corresponding coefficient of single-unit cementitious material related to cement type, dosage and pouring temperature; e is a constant, taken as 2.718; The concrete mixing temperature calculation model is: T0 = ∑Ti×W×C / ∑W×C Where: T0---concrete mixing temperature (°C); Ti --- Initial temperature (°C) of each component of concrete; concrete temperature. W — Mass of various materials per cubic meter of concrete (kg); C—Specific heat capacity of concrete components (kJ / kg.K); The calculation model for the concrete center temperature is as follows: T1(t) — Tj + Th·ξ(τ) Where: T1(t) — Calculated temperature at the center of concrete at age t (°C); Tj — Concrete pouring temperature (°C); ξ(τ)——Coefficient of temperature drop at age τ; The calculation model for the concrete surface temperature at 200mm below the surface is as follows: The thickness of the thermal insulation material is given by the formula: δ = (0.5hλ) i (T) s -T q )) / (λ0(T max -T b ))×K b Where: δ——thickness of the insulation layer on the concrete surface (m); λ0 — Thermal conductivity of concrete [W / (m²] K)]; λ i — Thermal conductivity of insulation materials [W / (m)] K)]; T s — Surface temperature of the concrete pouring body (°C); T q —Average atmospheric temperature (°C) when the concrete reaches its maximum temperature (3-5 days after pouring); T max —The highest temperature (°C) inside the concrete casting; h—actual thickness of the concrete structure (m); T s —T q —Take 15℃-20℃; T max —T b —Take 20℃-25℃; K b — Correction value for heat transfer coefficient.

6. The method for temperature monitoring and control during the large-volume concrete pouring process of wind turbine foundations according to claim 1, characterized in that, The first test element and the second test element shall meet the following requirements: 1) Under 25℃ conditions, the temperature measurement error should not exceed 0.3℃; 2) The temperature test range should be -30℃ to 20℃; 3) The test resolution of the strain testing element should not be greater than 5µε; 4) The strain test range should meet the requirement of 1000µε-1000µε; 5) The insulation resistance of the test element should be greater than 500MΩ.

7. The method for temperature monitoring and control during the large-volume concrete pouring process of wind turbine foundations according to claim 1, characterized in that, The requirements for installing the first test element and the second test element in step S20 are as follows: 1) The test element should be securely fixed and isolated from the structural steel reinforcement and the metal body of the fixing frame; 2) Test component leads are centrally arranged, labeled and protected along the routing direction; 3) Protective measures should be taken around the test element. The temperature test element and its leads should not be directly impacted or touched during feeding and vibration.

8. The method for temperature monitoring and control during the large-volume concrete pouring process of wind turbine foundations according to claim 1, characterized in that, After the concrete foundation of the wind turbine has set, the surface should be moistened with water and covered with a layer of plastic film and a layer of felt in a timely manner. Depending on the actual temperature difference, it is necessary to add another layer of felt. During the insulation period, the concrete should be checked frequently to see if it needs to be replenished with water. A layer of felt is used to cover the concrete sides to reduce air convection and achieve the purpose of heat preservation and control of the concrete sides.

Images