Method for calculating temperature stress and cracking risk of large-volume hydraulic concrete structure

Abstract

The invention discloses a large-volume hydraulic concrete structure temperature stress and cracking risk calculation method, which comprises the following steps of: 1, constructing a finite element model of a hydraulic large-volume concrete structure, and simulating a layered pouring construction process of the structure according to a layered pouring construction organization scheme; 2, according to mechanical parameters and thermodynamic parameters of concrete adopted by the structure, a control equation of hydration temperature rise, heat conduction, convective heat transfer, water cooling and shrinkage creep of all layers of concrete in the pouring process is deduced, and boundary conditions and initial conditions such as foundation constraint and atmospheric temperature are applied; 3, aiming at the control equation and the initial boundary condition, compiling a subprogram by using a programming language, and carrying out coupling calculation, linear superposition and algebraic summation on the strain of shrinkage, creep and thermal expansion effects in the layered pouring process of the structure; and 4, calculating and outputting temperature stress and a time-varying rule of crack initiation and expansion caused by the temperature stress, analyzing and demonstrating a calculation result, and determining a position with the maximum structure cracking risk.

Description

Technical Field

[0001] The invention relates to the technical field of water conservancy and hydropower engineering, and in particular to a method for calculating temperature stress and cracking risk of a large-volume hydraulic concrete structure. Background Art

[0002] The large-volume concrete structure of hydraulic engineering has the characteristics of large pouring volume, strong hydration heat effect, low tensile strength, less stress reinforcement, strong air and water flow, etc. In particular, the stress and strain generated by the shrinkage, creep and thermal expansion of concrete during the layered pouring process are very likely to exceed the tensile strength and ultimate tensile strain of concrete, resulting in structural cracking, affecting the impermeability, durability and safety and stability of hydraulic structures. Fully understanding the crack initiation and development laws of large-volume concrete structures and quantitatively calculating the cracking risk of the structure are of great practical significance for ensuring the construction safety and stable operation of large-volume concrete structures of hydraulic engineering.

[0003] At present, the calculation of cracking risk in the layered pouring construction process of large-volume concrete structures of hydraulic engineering mainly adopts the method of on-site construction monitoring and data collection and collation to observe the temperature and strain of concrete structures in real time, and then predict, analyze and calculate in advance. Most of these methods are based on design specifications and use fitting parameters to construct regression equations. Therefore, they cannot reflect the effects of heat conduction inside concrete, heat exchange between concrete and air and water flow, stress superposition and release, etc. in the layered pouring process of large-volume concrete structures, making it difficult to accurately predict the cracking risk of large-volume concrete structures. Summary of the invention

[0004] The purpose of the present invention is to provide a method for calculating the temperature stress and cracking risk of a large-volume hydraulic concrete structure. The method does not require on-site monitoring, fitting parameters, regression equations, etc., and by constructing control equations for the effects of hydration temperature rise, heat conduction, convection heat transfer, water cooling, shrinkage creep, etc., the strains of the effects of concrete shrinkage, creep, thermal expansion, etc. are quantitatively calculated, so as to accurately predict the cracking risk of a large-volume hydraulic concrete structure in the layered casting process.

[0005] To achieve the above object, the present invention adopts the following technical solutions: The method for calculating the temperature stress and cracking risk of a large-volume hydraulic concrete structure of the present invention comprises the following steps: Step 1, establishing a geometric model of a large-volume hydraulic concrete structure and a geometric model of its foundation, according to a set layered pouring construction plan, cutting the geometric model of the concrete structure in layers, using hexahedral units to divide the grid, simulating the layered pouring construction process of the concrete structure through activation and passivation operations of finite elements, thereby constructing a finite element model of the construction process of a large-volume hydraulic concrete structure; Step 2, based on the finite element model, according to the mechanical parameters and thermodynamic parameters of the structural concrete material and the foundation bedrock, derive the control equations of the hydration temperature rise, heat conduction, convection heat transfer, water cooling, and shrinkage creep of each layer of concrete during the structure casting process, apply corresponding foundation constraints, atmospheric temperature boundary conditions, and temperature and humidity initial conditions, and calculate and output the temperature of the layered concrete casting; Step 3, based on the temperature output by the control equation and the boundary initial conditions, derive the strain formula of the shrinkage, creep and thermal expansion of the concrete in the layered casting process of the structure, perform coupled calculation, linear superposition and algebraic summation on the strains generated by the shrinkage, creep and thermal expansion effects, and construct an operation program for the above calculation process by writing a Fortran language subroutine based on the Abaqus finite element calculation platform to automatically calculate the total strain of the concrete in the layered casting process; Step 4: Based on the calculated output of the temperature, stress, and strain of each layer of concrete in the layered casting process, the crack index equation is derived based on the temperature crack index theory to characterize the crack index and crack incidence rate, and the time-varying law of temperature stress and the crack initiation and expansion caused by it is output to evaluate the cracking risk of each layer of concrete in the layered casting process of the structure, thereby determining the location with the maximum cracking risk of the concrete structure.

[0006] Optionally, the modeling process of the finite element model includes: According to the design plan of the large-volume hydraulic concrete structure, a geometric model of the overall concrete structure is established. According to the layered pouring thickness and the layered construction plan of the concrete structure, the geometric model of the overall concrete structure is cut into layers. The finite element mesh of each layer of the concrete structure is divided by an eight-node primary hexahedron unit. Through the activation and passivation operations of the finite elements, the step-by-step pouring and superposition of each layer of concrete is realized, simulating the layered pouring construction process of the overall concrete structure.

[0007] Optionally, the control equation and the boundary initial condition establishment method include: Based on the finite element model, according to the mechanical parameters, thermodynamic parameters, test data and related research of structural concrete materials and foundation bedrock, a double exponential cement hydration heat calculation formula is established as follows: in: - Total heat of complete hydration of unit mass of cement; - Age of casting; , -Calculation coefficient of cement hydration heat: -Accumulated heat of hydration of cement at its age; For the heat transfer process of cement hydration heat in structural concrete, the following heat conduction equation is adopted: Where: - Concrete temperature; - Specific heat capacity of concrete; - Density of concrete; - Thermal conductivity of concrete; - Cumulative hydration heat of cement at age; Under the combined action of adiabatic temperature rise and cooling water pipes, the concrete temperature calculation formula is as follows: Where: - Initial temperature of concrete; - Temperature of the cooling water pipe inlet; - Water cooling function; - Adiabatic temperature rise of concrete; The calculation formula for the adiabatic temperature rise of concrete is as follows: Where: - Final adiabatic temperature rise of concrete; - Pouring age; Furthermore, in order to improve the calculation accuracy of concrete temperature, the water cooling function and adiabatic temperature rise function in the form of midpoint age are adopted during calculation as follows: Water cooling function Adiabatic temperature rise function Where: - Water cooling function; - Pouring age; - Cooling coefficient of the cooling water pipe; Therefore, the concrete temperature is simplified to: Where: - Initial temperature of concrete; - Temperature of the cooling water pipe inlet; - Adiabatic temperature rise constant; - Water-cooling function; Boundary condition, the heat exchange at the contact surface between concrete and the atmosphere, adopts the third kind of boundary condition: Wherein: - Thermal conductivity of concrete; - Convective heat transfer coefficient at the contact surface between concrete and air; - Surface temperature of concrete; - Atmospheric temperature; Initial condition, the temperature of concrete at the initial moment is as follows: Wherein: - Initial temperature of concrete; 、 Both are atmospheric temperatures; According to the above formula, calculate and output the temperature of concretes placed in layers.

[0008] Optionally, the calculation method for the total strain of concretes placed in layers includes: Based on the temperature of concretes placed in layers calculated and output above, deduce the calculation formulas for the creep strain, shrinkage strain, and thermal strain of concretes placed in layers, perform linear superposition and algebraic summation to obtain the total strain of concretes placed in layers, as shown below: Calculation formula for the strain generated by concrete creep: Wherein: - Concrete stress; - Concrete creep coefficient; The formula for the concrete creep coefficient is as follows: Wherein: - Total construction time of structural concrete placement; - Curing age; The calculation formula for the strain generated by concrete shrinkage is as follows: in: -compressive strength of concrete; - Ratio of concrete volume to surface area; - relative humidity; The calculation formula of concrete thermal strain is as follows: in: - Coefficient of thermal expansion of concrete; -Current age Concrete temperature; According to the above formula, the total strain and stress of layered concrete pouring are calculated and output.

[0009] Optionally, the method for calculating the risk of cracking of structure layered concrete pouring includes: Based on the temperature, stress and strain of each layer of concrete cast in layers calculated above, the crack index equation is derived by using the temperature crack index theory. The formula to characterize the crack index and crack incidence rate is as follows: in: -Tensile strength of layered concrete; - tensile stress in layered concrete; Through the calculated temperature, stress and total strain of the layered concrete casting, the cracking risk of each layer of concrete in the layered casting process of large-volume hydraulic concrete structure is evaluated, and the location with the greatest risk of structural concrete cracking is determined.

[0010] Compared with the prior art, the present invention has the following significant improvements: 1) The present invention aims at the layered casting process of large-volume hydraulic concrete structures. By first constructing an overall geometric model, then layering and sectioning, and then finite element meshing, according to the construction plan of layered casting of the structure, the precise layering of the finite elements of each layer of the concrete structure is achieved; 2) The present invention calculates and analyzes the hydration temperature rise, heat conduction, convection heat transfer, water cooling, shrinkage creep, etc. during the layered pouring process of large-volume hydraulic concrete structures. It does not require manual setting of fitting parameters and regression equations, but is achieved by constructing control equations and boundary initial conditions; 3) The present invention aims at the strain problem of concrete shrinkage, creep, thermal expansion and the like during the layered casting process, and adopts the method of coupling calculation, linear superposition and algebraic summation to derive the total strain calculation formula of the layered casting concrete structure under the combined action of the three factors; 4) Based on the temperature crack index theory, the present invention realizes the quantitative characterization of the crack index and the crack incidence rate by deriving the crack index equation, achieves the accurate assessment of the cracking risks of the concrete in each layer during the layered pouring process of the structure, and determines the position with the greatest cracking risk of the structure. Description of the Drawings

[0011] Figure 1 is a schematic flow chart of the calculation method for the temperature stress and cracking risk of the mass concrete structure of the lock in the embodiment of the present invention.

[0012] Figure 2 is a schematic front elevation view of the sectional view of the geometric model of the lock concrete and the foundation bedrock in the embodiment of the present invention.

[0013] Figure 3 is a schematic back elevation view of the sectional view of the geometric model of the lock concrete and the foundation bedrock in the embodiment of the present invention.

[0014] Figure 4 is a schematic front elevation view of the mesh division of the finite element model of the lock concrete and the foundation bedrock in the embodiment of the present invention.

[0015] Figure 5 is a schematic back elevation view of the mesh division of the finite element model of the lock concrete and the foundation bedrock in the embodiment of the present invention.

[0016] Figure 6.1 is Figure 4 an enlarged schematic view of part A.

[0017] Figure 6.2 is Figure 5 an enlarged schematic view of part B. Detailed Embodiment

[0018] As Figure 1 shown, the calculation method for the temperature stress and cracking risk of the mass hydraulic concrete structure described in the present invention includes the following steps: Step 1: According to the design scheme of the lock concrete structure of a certain large - scale water conservancy project, establish the geometric model of the overall lock structure. According to the layered pouring thickness of the lock concrete structure, perform layered sectioning on the overall structure geometric model. Use the eight - node first - order hexahedral element to perform finite - element mesh division on each layer of the concrete structure. According to the layered pouring construction organization plan of the structure, realize the step - by - step pouring superposition of each layer of concrete by activating and deactivating the finite elements of each layer of the concrete structure, and simulate the layered pouring construction process of the structure, thereby constructing the finite - element model for the layered pouring construction of the lock structure of the water conservancy project. Step 2: For the finite - element model for the layered pouring construction of the lock structure established above, establish a cement hydration heat calculation formula in the form of a double - exponential according to the mechanical parameters, thermodynamic parameters, test data, and relevant research of the concrete material and the foundation bedrock, as follows: Among them, , , , , respectively represent the total heat of complete hydration of unit mass of cement, casting age, cement hydration heat calculation coefficient, and the cumulative hydration heat of cement at age ; For the heat transfer process of cement hydration heat in concrete, the following heat conduction equation is adopted: Among them, , , , , respectively represent the concrete temperature, specific heat capacity, density, thermal conductivity, and the cumulative hydration heat of cement at age ; Under the combined action of adiabatic temperature rise and cooling water pipes, the concrete temperature calculation formula is as follows: Among them, , , , respectively represent the initial concrete temperature, cooling water pipe inlet temperature, water cooling function, and the adiabatic temperature rise of concrete; The calculation formula for the adiabatic temperature rise of concrete adopts the following form: Among them, , respectively represent the final adiabatic temperature rise of concrete, casting age; Beneficially or exemplarily, in order to improve the calculation accuracy, the water cooling function and adiabatic temperature rise function in the form of midpoint age can be adopted during calculation, as follows: Among them, , , , respectively represent the water cooling function, casting age, calculation parameter, and adiabatic temperature rise calculation function; Therefore, the concrete temperature can be simplified to the following formula: Among them, , , , respectively represent the initial temperature of concrete, the inlet temperature of the cooling water pipe, the adiabatic temperature rise constant, and the water cooling function; Boundary conditions, the heat exchange at the contact surface between concrete and the atmosphere, adopt the third type of boundary conditions: Among them, and and and respectively represent the thermal conductivity of concrete, the convective heat transfer coefficient at the contact surface between concrete and air, the surface temperature of concrete, and the atmospheric temperature; Initial conditions, the temperature of concrete at the initial moment is as follows: Among them, and both represent the initial temperature of concrete, represents the atmospheric temperature; According to the above formula, calculate and output the temperature of the concreted in layers; Step 3, according to the temperature of the concreted in layers calculated and output above, deduce the calculation formulas for the creep strain, shrinkage strain, and thermal strain of the concreted in layers, perform linear superposition and algebraic summation, and based on the Abaqus finite element calculation platform, by writing a Fortran language subroutine, construct an operation program for the above calculation process to automatically calculate the total strain of the concreted in the process of concreting in layers, and obtain the total strain of the concreted in layers, as follows: Calculation formula for the strain generated by concrete creep: Among them, and respectively represent the concrete stress and the concrete creep degree, and the formulas are as follows: Among them, and respectively represent the total construction time of the structural concreting and the concreting age; Calculation formula for the strain generated by concrete shrinkage: Among them, and and respectively represent the compressive strength of concrete, the ratio of the volume to the surface area of concrete, and the relative humidity.

[0019] Calculation formula for the thermal strain of concrete: Among them, and respectively represent the coefficient of thermal expansion of concrete and the current age of the concrete temperature; According to the above formula, calculate and output the total strain and stress of the concretes in layered pouring; Step 4, based on the temperatures, stresses, and strains of the concretes in each layer of the layered pouring calculated and output above, use the temperature crack index theory to derive the crack index equation to characterize the crack index and the crack incidence rate, Among them, and respectively represent the tensile strength and tensile stress of the concretes in layered pouring; Evaluate the cracking risks of the concretes in each layer during the layered pouring process of the mass hydraulic concrete structure through the temperatures, stresses, and total strains of the concretes in layered pouring calculated above, and determine the position with the greatest structural cracking risk; For a better understanding of the present invention, the present invention provides a specific embodiment of the concrete structure of a certain large - scale water conservancy project lock for reference.

[0020] The method for calculating the temperature stress and cracking risk of the concrete structure of a certain large - scale water conservancy project lock of the present invention includes the following steps: Step 1, as Figure 2 and Figure 3 shown, establish the geometric model of the overall lock structure: Set the effective dimensions of the lock structure in this embodiment to be 200m×25m×12m (length×width×depth). Select the pier 1 structure as the research object, with a height of 37.2 meters, a width of 36.4 meters, and a length of 26.5 meters. Its concrete structure adopts the layered pouring process with a layer thickness of 1.5m, and the total pouring duration is about 262 days. This geometric model includes two parts: pier concrete and foundation 2. The pier is modeled according to the design dimensions, the width of the foundation part is 3 times the pier structure size, and the depth of the foundation is 1 time the structure height. According to the layer thickness of the pier layered pouring, the geometric model is divided by layered cutting (shown by the solid line in the figure, which is the cutting plane); to improve the quality of mesh division, the foundation part is also cut and divided. The mesh division of the geometric model uses eight-node hexahedral elements; the mesh division size is: 0.5m along the height direction of the pier part and 3m along the height direction of the foundation part. By activating and deactivating the finite elements of each layer of concrete, the step-by-step pouring and superposition of each layer of concrete are realized, and the layered pouring process of this structure is simulated; the finite element model of the layered pouring construction of the lock concrete and the foundation bedrock is as Figure 4 , Figure 5 shown; Step 2, according to the finite element model established above, establish a cement hydration heat calculation formula in the form of a double exponential, as shown below: where, , , , , respectively represent the total heat of complete hydration of unit mass of cement, pouring age, cement hydration heat calculation coefficient, and the cumulative hydration heat of cement at age ; For the heat transfer process of cement hydration heat in the concrete, use the following heat conduction equation: where, , , , , respectively represent the concrete temperature, specific heat capacity, density, thermal conductivity, and the cumulative hydration heat of cement at age ; Under the combined action of adiabatic temperature rise and cooling water pipes, the concrete temperature calculation formula is as follows: where, , , , respectively represent the initial temperature of the concrete, the inlet temperature of the cooling water pipe, the water cooling function, and the adiabatic temperature rise of the concrete; The calculation formula for the adiabatic temperature rise of concrete is in the following form: Among them, and respectively represent the adiabatic temperature rise of concrete at the casting age, the casting age, and the ultimate adiabatic temperature rise of concrete takes the value of 25; To improve the calculation accuracy, the water-cooling function and the adiabatic temperature rise function in the form of the midpoint age can be adopted during the calculation, as shown below: Among them, the water pipe cooling coefficient takes the value of 0.0437 1 / day; The concrete temperature can be simplified into the following formula: Among them, the initial temperature of concrete takes the value of 12°C, the water inlet temperature of the cooling water pipe takes the value of 9°C, and the ultimate adiabatic temperature rise of concrete takes the value of 25; Boundary condition, the heat exchange at the contact surface between concrete and the atmosphere adopts the third kind of boundary condition: Among them, the thermal conductivity of concrete takes the value of 200.88 kJ / (m·d·°C), and the convective heat transfer coefficient at the contact surface between concrete and air takes the value of 432 kJ / (m 2 ·d·°C) for the side surface and 768 kJ / (m 2 ·d·°C) for the top surface, the surface temperature of concrete takes the value of 12°C, and the atmospheric temperature takes the value of 23°C; Initial condition, the temperature of concrete at the initial moment is as follows: Among them, and both represent the initial temperature of concrete, and the atmospheric temperature takes the value of 23°C; The mechanical and thermodynamic property indexes of concrete and bedrock are shown in Table 1 and Table 2; Table 1 Mechanical and thermodynamic property indexes of concrete Table 2 Mechanical and Thermodynamic Performance Parameter Indexes of Bedrock Step 3: Based on the temperature of the concrete poured in layers calculated above, derive the calculation formulas for the creep strain, shrinkage strain, and thermal strain of the concrete poured in layers, perform linear superposition and algebraic summation. Based on the Abaqus finite element calculation platform, by writing a Fortran language subroutine, construct an operation program for the above calculation process to automatically calculate the total strain of the concrete during the layered pouring process, and obtain the total strain of the concrete poured in layers as follows: Calculation formula for the strain generated by concrete creep: Among them, 、 represent the concrete stress and the concrete creep degree respectively, and the formulas are as follows: Among them, 、 represent the total construction time of the structure pouring and the pouring age respectively; Calculation formula for the strain generated by concrete shrinkage: Among them, represent the concrete compressive strength takes a value of 35 MPa, the ratio of the concrete volume to the surface area takes a value of 0.56, and the relative humidity takes a value of 95%; Calculation formula for the thermal strain of concrete: Among them, the concrete thermal expansion coefficient takes a value of 8×10 -6 1 / ℃; According to the above formulas, calculate and output the stress of the concrete poured in layers; Step 4: Based on the temperatures, stresses, and strains of each layer of the concrete poured in layers calculated above, use the temperature crack index theory to derive a crack index equation to characterize the crack index and the crack incidence rate; Among them, the tensile strength of the concrete poured in layers takes a value of 3 MPa; By using the temperature, stress, and total strain of the concrete in the layered pouring calculated above, evaluate the cracking risk of each layer of concrete during the layered pouring process of the mass hydraulic concrete structure, and determine the location 3 with the greatest cracking risk of the structure, as Figure 6.1 , Figure 6.2 shown.

Claims

1. A method for calculating temperature stress and cracking risk of large-volume hydraulic concrete structures, characterized in that: The steps include: Step 1, establishing a geometric model of a large-volume hydraulic concrete structure and a geometric model of its foundation, according to a set layered pouring construction plan, cutting the geometric model of the concrete structure in layers, using hexahedral units to divide the grid, simulating the layered pouring construction process of the concrete structure through activation and passivation operations of finite elements, thereby constructing a finite element model of the construction process of a large-volume hydraulic concrete structure; Step 2, based on the finite element model, according to the mechanical parameters and thermodynamic parameters of the structural concrete material and the foundation bedrock, derive the control equations of the hydration temperature rise, heat conduction, convection heat transfer, water cooling, and shrinkage creep of each layer of concrete during the structure casting process, apply corresponding foundation constraints, atmospheric temperature boundary conditions, and temperature and humidity initial conditions, and calculate and output the temperature of the layered concrete casting; Step 3, based on the temperature calculated and output by the control equation and the boundary initial conditions, derive the strain formula of the shrinkage, creep and thermal expansion of the concrete during the layered casting process of the structure, perform coupled calculation, linear superposition and algebraic summation on the strains generated by the shrinkage, creep and thermal expansion effects, and automatically calculate the total strain of the concrete during the layered casting process; Step 4: Based on the calculated output of the temperature, stress, and strain of each layer of concrete in the layered casting process, the crack index equation is derived based on the temperature crack index theory to characterize the crack index and crack incidence rate, and the time-varying law of temperature stress and the crack initiation and expansion caused by it is output to evaluate the cracking risk of each layer of concrete in the layered casting process of the structure, thereby determining the location with the maximum cracking risk of the concrete structure.

2. The method for calculating temperature stress and cracking risk of large-volume hydraulic concrete structures according to claim 1 is characterized in that: The modeling process of the finite element model includes: According to the design plan of the large-volume hydraulic concrete structure, a geometric model of the overall concrete structure is established. According to the layered pouring thickness and the layered construction plan of the concrete structure, the geometric model of the overall concrete structure is cut into layers. The finite element mesh of each layer of the concrete structure is divided by an eight-node primary hexahedron unit. Through the activation and passivation operations of the finite elements, the step-by-step pouring and superposition of each layer of concrete is realized, simulating the layered pouring construction process of the overall concrete structure.

3. The method for calculating temperature stress and cracking risk of large-volume hydraulic concrete structures according to claim 1 is characterized in that: The control equation and the boundary initial condition establishment method include: Based on the finite element model, according to the mechanical parameters, thermodynamic parameters, test data and related research of structural concrete materials and foundation bedrock, a double exponential cement hydration heat calculation formula is established as follows: in: - Total heat of complete hydration of unit mass of cement; - Casting age; , -Calculation coefficient of cement hydration heat; -Accumulated heat of hydration of cement at its age; The following heat conduction equation is used for the heat transfer process of cement hydration heat release inside structural concrete: in: - concrete temperature; -Specific heat capacity of concrete; - concrete density; - Thermal conductivity of concrete; - Cement age The accumulated heat of hydration at Under the combined effect of adiabatic temperature rise and cooling water pipe, the concrete temperature calculation formula is as follows: in: - initial concrete temperature; -Cooling water pipe inlet temperature; -Water cooling function; - Adiabatic temperature rise of concrete; The calculation formula for the adiabatic temperature rise of concrete is as follows: in: - Final adiabatic temperature rise of concrete; - Age of casting.

4. The method for calculating temperature stress and cracking risk of large-volume hydraulic concrete structures according to claim 3 is characterized in that: The water cooling function and adiabatic temperature rise function of concrete temperature in the form of mid-point age are as follows: Water cooling function Adiabatic temperature rise function in: -Water cooling function; - Casting age; -Cooling coefficient of cooling water pipes; Therefore, the concrete temperature is simplified to: in: - initial concrete temperature; -Cooling water pipe inlet temperature; -Adiabatic temperature rise constant; -Water cooling function; Boundary conditions, heat exchange between concrete and atmosphere, adopt the third type of boundary conditions: in: - Thermal conductivity of concrete; - Convective heat transfer coefficient between concrete and air; - concrete surface temperature; - atmospheric temperature; Initial conditions, the initial temperature of concrete is as follows: in: - initial concrete temperature; , are atmospheric temperatures; According to the above formula, calculate and output the temperature of layered concrete pouring.

5. The method for calculating temperature stress and cracking risk of large-volume hydraulic concrete structures according to claim 1 is characterized in that: The method for calculating the total strain of layered concrete pouring includes: Based on the calculated output of the layered concrete pouring temperature, the calculation formulas for the creep strain, shrinkage strain, and thermal strain of the layered concrete pouring are derived, and linear superposition and algebraic summation are performed to obtain the total strain of the layered concrete pouring, as shown below: The strain calculation formula for concrete creep is: in: - concrete stress; -Concrete creep; the formula is as follows: The formula for concrete creep is as follows: in: -Total construction time for pouring concrete for the structure; - Age of casting; The strain calculation formula for concrete shrinkage is as follows: in: -compressive strength of concrete; - Ratio of concrete volume to surface area; - relative humidity; The calculation formula of concrete thermal strain is as follows: in: - Coefficient of thermal expansion of concrete; - concrete temperature at current age; According to the above formula, the total strain and stress of layered concrete pouring are calculated and output.

6. The method for calculating temperature stress and cracking risk of large-volume hydraulic concrete structures according to claim 1 is characterized in that: The method for calculating the risk of cracking of structure layered concrete pouring includes: Based on the temperature, stress and strain of each layer of concrete cast in layers calculated above, the crack index equation is derived by using the temperature crack index theory. The formula to characterize the crack index and crack incidence rate is as follows: in: -Tensile strength of layered concrete; - tensile stress in layered concrete; Through the calculated temperature, stress and total strain of the layered concrete casting, the cracking risk of each layer of concrete in the layered casting process of large-volume hydraulic concrete structure is evaluated, and the location with the greatest risk of structural concrete cracking is determined.

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