A damage assessment method for concrete materials eroded by high-temperature and high-speed airflow

Abstract

The present invention provides a damage assessment method for high-temperature and high-speed airflow erosion concrete materials, comprising the following steps: step 1, establishing a concrete material model through Digmat-FE software, and performing mesh division; step 2, refining the mesh in ANSA software; step 3, performing transient heat conduction calculation in Abaqus software; step 4, calculating aerodynamic shear force, pore internal pressure, airflow vertical load and concrete surface thermal convection coefficient; step 5, performing transient heat-solid coupling calculation in Abaqus software; step 6, drawing conclusions based on the calculation data results. The evaluation method designed by the present invention is scientific and reasonable, and preferably adopts a variety of software for coordinated use, has good modeling and simulation effects, and the conclusions are clear and easy to obtain. The evaluation results are scientific and reliable, and can be promoted for use.

Description

Technical Field

[0001] The invention relates to the technical field of concrete performance research, and in particular to a damage assessment method for concrete materials eroded by high-temperature and high-speed airflow. Background Art

[0002] Buildings made of concrete materials play an irreplaceable and important role in social development. Research on the high temperature and anti-explosion performance of concrete buildings has important guiding significance for building safety. By studying the erosion damage of high-temperature and high-speed airflow to concrete, we can provide technical references for specifying concrete technical standards and facilitate more detailed quality evaluation of concrete materials.

[0003] However, there is still a lack of a reliable and efficient research method. At present, scholars have done little research on the mechanical erosion damage mechanism of concrete under pure meteorological conditions, and in order to improve the modeling efficiency of aggregate mesoscopic models, the complex concrete structure is generally simplified to a certain extent. In addition, the research results on transient heat transfer under the impact of high-temperature and high-speed airflow are also insufficient. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a damage assessment method for concrete materials eroded by high-temperature and high-speed airflow in response to the above-mentioned deficiencies in the prior art. The method is scientific and reasonable, convenient and fast, and can intuitively and systematically derive the erosion performance of concrete materials resistant to high-temperature and high-speed airflow, providing technical support for actual production and application, and has important scientific research value and economic value.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a damage assessment method for concrete material eroded by high-temperature and high-speed airflow, characterized in that it comprises the following steps:

[0006] Step 1: Modeling is done by Digmat-FE software, and meshing is performed to obtain a preliminary mesh model of concrete material;

[0007] Step 2: Refine the preliminary mesh model in ANSA software to obtain the concrete material research model;

[0008] Step 3: Load high-temperature and high-speed airflow into the concrete material research model in Abaqus software;

[0009] Step 4: Calculate the vertical load of airflow, thermal convection coefficient of concrete surface, pore internal pressure and aerodynamic shear force on the loaded concrete material research model;

[0010] Step 5. Perform transient thermal-solid coupling calculations on the concrete material research model in Abaqus software, calculate the stress cloud map of the concrete material research model, and then calculate the heat transfer depth, displacement cloud map, damage area and mass loss rate to determine the degree of damage to the concrete material eroded by high-temperature and high-speed airflow.

[0011] Preferably, it is characterized in that the specific steps of modeling by Digmat-FE software in step 1 are:

[0012] S101. A three-dimensional random aggregate mesoscopic model is established in Digmat-FE software. The aggregate in the random aggregate mesoscopic model is in the shape of an ellipsoid and contains ellipsoidal pores.

[0013] S102, setting the volume fraction of aggregate in the aggregate mesoscopic model to 70%, the major axis size of the aggregate to 5-20 mm, setting the volume fraction of pore in the aggregate mesoscopic model to 1%, and the major axis size of the pore to 1-5 mm;

[0014] S103, setting the pores and the aggregate model to have a certain gap and not overlap, and all of them are randomly distributed in the three-dimensional random aggregate mesoscopic model matrix;

[0015] S104. On the basis of the three-dimensional random aggregate mesoscopic model obtained in S103, a preliminary grid size is set to obtain a preliminary grid model.

[0016] Preferably, the specific operation steps of step 2 are:

[0017] S201, exporting the preliminary mesh model obtained in S104 to Ansa software in inp format;

[0018] S202. Define the elastic modulus, Poisson's ratio, specific heat capacity, thermal expansion coefficient, density and thermal conductivity of aggregate and concrete;

[0019] S203. In the Ansa software, a concrete model is added to the preliminary mesh model so that the aggregate is embedded in the concrete and the mesh is re-divided, wherein the aggregate and the concrete model mesh share nodes to form a relatively fixed relationship, thereby forming a concrete material research model.

[0020] Preferably, the specific operation of step three is: the concrete material research model is simulated and embedded in the ground foundation pit, the four sides of the concrete material research model are fixed in the X and Y directions respectively, the ground is fixed in the Z direction, the upper surface of the concrete material research model is impacted by the high-speed airflow and forms an angle α with the upper plane of the concrete material research model, the initial temperature of the concrete material research model is set to 20°C, and the airflow impact can be simplified to the impact force P;

[0021] Preferably, the specific steps of step 4 include:

[0022] S401. Calculation of vertical airflow load: Decompose the impact force P into the vertical force P in the vertical direction. b and horizontal shear force f i , the impact force P is set to P = mv, m is the mass flow rate of the gas per second, here it is 6.376 kg / s, v is the effective discharge velocity of the gas flow; the vertical load P b =mvsinα;

[0023] S402, Concrete surface heat convection coefficient:

[0024] The impingement heat transfer of high-temperature and high-speed airflow includes heat convection between the hot airflow and the upper surface of the concrete and heat conduction inside the concrete.

[0025] On the fluid side, the cylindrical channel for discharging high-temperature and high-speed airflow is defined as the exhaust channel. The heat transfer process between the hot airflow in the exhaust channel and the wall of the concrete material research model is regarded as a non-circular channel turbulent forced convection heat transfer, and its Nusselt number is calculated using the Gnielinski formula

[0026]

[0027] For gas

[0028]

[0029] Where l is the exhaust duct length; d is the exhaust duct equivalent diameter; f is the Darcy drag coefficient of turbulent flow in the exhaust duct; Re is the Reynolds number, Pr f is the Prandtl constant of the thermal flow;

[0030] Exhaust duct equivalent diameter

[0031] In the above formula, A is the cross-sectional area of ​​the hot air flow in the exhaust duct; C is the circumference of the exhaust duct, that is, the part of the exhaust duct wall in contact with the hot air flow;

[0032] f=(1.82lgRe-1.64) -2

[0033]

[0034] In the formula, ρ l is the fluid density; u ∞ is the incoming flow velocity; μ is the fluid dynamic viscosity, and μ = ρν; x is the characteristic length, that is, the equivalent diameter of the exhaust duct;

[0035]

[0036] Where ν is the fluid kinematic viscosity; a is the fluid thermal conductivity.

[0037] After Nu is determined, the convective heat transfer coefficient between the hot air flow and the exhaust duct wall can be obtained according to its definition formula;

[0038]

[0039] Where λ is the thermal conductivity of the fluid;

[0040] Combining the above formulas, we get

[0041]

[0042] Heat convection formula q=h|T f -T w |;

[0043] On the solid side of the exhaust duct, that is, inside the concrete, heat conduction mainly occurs, and heat flows from high temperature to low temperature. According to Fourier's law, the expression of heat flux density is:

[0044]

[0045] Where q is the heat flux in W / (m 2 ), λ is the thermal conductivity in W / (m·℃), T is the temperature in ℃;

[0046] Effective thermal conductivity of unsaturated concrete eff The relationship with temperature and pore water saturation is as follows

[0047]

[0048] In the above formula, d (T) is the thermal conductivity of concrete in a dry environment, and its expression is:

[0049] λ d (T) = λ d0 (1+A λ (T-T0))

[0050] Where T0 is the reference temperature, which is 298.15K; λ d0 Take 1.67W / mK; A λ Take -1.017×10 -3 K -1 ρ l is the density of water; ρ s is the density of concrete; n is the porosity of concrete;

[0051] In a three-dimensional Cartesian coordinate system, assuming that the temperature of a point inside the concrete is T, the heat transfer of the concrete material is isotropic λ = λ eff, the three-dimensional unsteady-state heat conduction differential equation inside the concrete structure without internal heat source is:

[0052]

[0053] Where, ρ is the density of concrete; c is the specific heat capacity of concrete at constant pressure;

[0054] The heat conduction differential equation is a mathematical expression that describes the common characteristics of the heat conduction process. In order to obtain the transient temperature field distribution of concrete, it is necessary to give the temperature distribution and thermal boundary conditions of the concrete at the initial moment according to the actual situation. For non-steady-state heat transfer, the initial conditions for concrete heat transfer calculation are:

[0055] T(x,y,z,0)=T0

[0056] Where, T o is the initial temperature of concrete;

[0057] The convection heat transfer coefficient h of the boundary surface between the fluid and the concrete and the temperature T of the hot air flow are known. f ,Right now:

[0058]

[0059] The temperature field of concrete is calculated by solving the convection heat transfer coefficient between the hot air flow and the exhaust duct wall (concrete) and loading it onto the concrete boundary surface as a thermal boundary condition.

[0060] S403. Calculate the internal pressure of the pores: saturated steam pressure P vs Calculated by the empirical formula given by Hyland and Wexler

[0061]

[0062] Where C8 = -5.8x10 3 , C9=1.3915,C 10 =-4.8640×10 2 , C 11 =4.1765×10 -5 , C 12 =-1.445,C 13 =6.5460, when T≧674.3K, P vs =22.09MPa;

[0063] S404. Calculation of aerodynamic shear force: The viscous force on the model surface needs to be obtained by summing the friction forces of all wall units, that is:

[0064]

[0065] Where: Fv is the total viscous force; f i is the viscous friction force of wall unit i; c fi is the viscous friction coefficient of wall unit i; Q Ai is the local dynamic pressure of wall unit i; A i is the area of ​​wall unit i;

[0066] The viscous friction coefficient c of element i fi The reference temperature method based on local flow field parameters is used for calculation, namely:

[0067]

[0068] ρ e 、u e , μ e are the density, velocity and dynamic viscosity coefficient of the outer edge of the boundary layer, respectively, and x is the length of the streamline emanating from the leading edge of the plate;

[0069] Local dynamic pressure Q of unit i Ai is the dynamic pressure at reference temperature T:

[0070] Q Ai =0.5ρu e 2

[0071] Then the viscous friction force of unit i can be expressed as:

[0072]

[0073] The friction force f i The direction is the tangent of the streamline, which is the velocity direction of the local wall. Let the tangent unit vector be τ i =(τ x , τ y , τ z ) Friction force f of unit i i The three components in the rectangular coordinate system (x, y, z) are:

[0074] f ix =f i τ x

[0075] f iy =f i τ y

[0076] f iz =f i τ z

[0077] Therefore, the three components of the total viscous force on the surface can be expressed in the rectangular coordinate system as follows:

[0078]

[0079]

[0080]

[0081] S405. After dividing the concrete material research model into impact zones and impact areas according to different impact areas, a working condition table is prepared.

[0082] Preferably, the specific steps of step five are:

[0083] S501. The calculation results in step 4 are divided into two parts. The first part is the stress cloud map, heat transfer depth, displacement cloud map, damage area and mass loss rate of the model under the impact of high-temperature airflow in the impact area and after the impact area; the second part is the stress cloud map, heat transfer depth, displacement cloud map, damage area and mass loss rate of the model when observing the changes of airflow impact angle, airflow temperature and airflow impact speed in the impact area;

[0084] S502, respectively, in the impact zone and after the impact zone, calculate the curves of the aerodynamic shear force, vertical load and thermal convection coefficient changing with time according to the formula in step 4; then calculate the transient temperature field of the concrete material research model, import the aerodynamic shear force, vertical load and thermal convection coefficient data into the calculation and analysis to obtain the temperature inside the pores, the temperature inside the pores is the maximum temperature of the surface layer of the concrete material research model, establish a heat-solid coupling field from the pore pressure and the pore temperature to obtain a stress cloud map, then remove the failed unit and measure the mass of the failed unit to obtain the mass loss rate of the concrete material research model, measure the volume of the failed unit, divide the volume of the failed unit by the surface area of ​​the concrete to obtain the average depth of the surface peeling layer, finally, by setting the compressive strength standard of different concrete grades, obtain the comparison of the degree of damage of concrete of different grades, and finally obtain the simulation calculation results of the four areas;

[0085] S503, in the impact zone, the impact angle, temperature and speed of the high-temperature and high-speed airflow are changed by the control variable method, and the loss degree of the impact zone under different conditions is calculated respectively, and the calculation method is the same as the calculation method provided in S502;

[0086] S504. A comparative analysis is performed on the calculation results obtained from S502 and S503 to draw conclusions on the damage of concrete under high-temperature and high-speed airflow erosion.

[0087] Compared with the prior art, the present invention has the following advantages:

[0088] 1. The present invention is scientific, reasonable, convenient and fast, and can intuitively and systematically obtain the erosion resistance of concrete to high-temperature and high-speed airflow, providing technical support for actual production and application, and has important scientific research value and economic value.

[0089] 2. The present invention can be used to evaluate the mechanism of erosion damage to concrete materials in buildings made of concrete materials when they are impacted by high-temperature and high-speed airflows, such as explosive fires, and analyze and summarize the laws of erosion damage under different speeds, temperatures and pressures.

[0090] 3. The present invention can provide ideas and basis for the establishment of a three-dimensional random aggregate microscopic model of concrete materials, and provide a reliable research method for the damage mechanism of concrete under the impact of high-temperature and high-speed airflow.

[0091] 4. The present invention uses Digmat-FE software, ANSA software and Abaqus software respectively, which can fully utilize the advantages and characteristics of each software to establish a three-dimensional random concrete aggregate micro-model for high-temperature and high-speed airflow erosion simulation research, with good modeling effect and fast simulation calculation speed.

[0092] The present invention is further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0093] Figure 1 It is an operation flow chart of the present invention.

[0094] Figure 2 It is a schematic diagram of load loading in the present invention.

[0095] Figure 3 It is a schematic diagram of thermal convection loading in the present invention.

[0096] Figure 4 It is a schematic diagram of the power-thermal shock effect of the hot air flow in the present invention.

[0097] Figure 5 Schematic diagram of heat transfer of the exhaust duct in the present invention.

[0098] Figure 6 Schematic diagram of saturated steam pressure and pore temperature in the present invention.

[0099] Figure 7 It is the calculation condition table in the present invention.

[0100] Figure 8 It is a graph showing the change of pneumatic shear force over time in the present invention.

[0101] Fig. 9 It is the vertical load variation curve of the present invention.

[0102] Fig.10It is the curve of the heat convection coefficient changing with time in the present invention.

[0103] Fig.11 It is a transient heat conduction temperature distribution cloud diagram of the impact zone in the present invention.

[0104] Fig.12 It is the equivalent stress cloud diagram of the impact area of ​​the model in the present invention.

[0105] Fig.13 It is the equivalent displacement cloud diagram of the impact zone of the model in the present invention.

[0106] Fig.14 It is the stress cloud diagram of the unit without the failed impact zone of the C30 model in the present invention.

[0107] Fig.15 It is the change of concrete volume loss rate over time in the present invention.

[0108] Fig.16 It is a summary table of calculation results of the impact zone and after the impact zone in the present invention.

[0109] Fig.17 It is a summary table of the results of the impact zone at different impact angles in the present invention.

[0110] Fig.18 It is a curve showing the variation of the average depth of the shedding layer with time at different air flow temperatures in the present invention.

[0111] Fig.19 It is a summary table of the results of the impact zone at different impact temperatures in the present invention.

[0112] Fig. 20 It is the change of mass loss rate with time at different air flow velocities in the present invention.

[0113] Fig.21 It is a summary table of the results of the impact zone at different impact velocities in the present invention. DETAILED DESCRIPTION

[0114] like Figure 1 As shown, the present invention comprises the following steps:

[0115] Step 1: Modeling is done by Digmat-FE software, and meshing is performed to obtain a preliminary mesh model of concrete material;

[0116] Step 2: Refine the preliminary mesh model in ANSA software to obtain the concrete material research model;

[0117] Step 3: Load high-temperature and high-speed airflow into the concrete material research model in Abaqus software;

[0118] Step 4: Calculate the vertical load of airflow, thermal convection coefficient of concrete surface, pore internal pressure and aerodynamic shear force on the loaded concrete material research model;

[0119] Step 5. Perform transient thermal-solid coupling calculations on the concrete material research model in Abaqus software, calculate the stress cloud map of the concrete material research model, and then calculate the heat transfer depth, displacement cloud map, damage area and mass loss rate to determine the degree of damage to the concrete material eroded by high-temperature and high-speed airflow.

[0120] Preferably, it is characterized in that the specific steps of modeling by Digmat-FE software in step 1 are:

[0121] S101. A three-dimensional random aggregate mesoscopic model is established in Digmat-FE software. The aggregate in the random aggregate mesoscopic model is in the shape of an ellipsoid and contains ellipsoidal pores.

[0122] S102, setting the volume fraction of aggregate in the aggregate mesoscopic model to 70%, the major axis size of the aggregate to 5-20 mm, setting the volume fraction of pore in the aggregate mesoscopic model to 1%, and the major axis size of the pore to 1-5 mm;

[0123] S103, setting the pores and the aggregate model to have a certain gap and not overlap, and all of them are randomly distributed in the three-dimensional random aggregate mesoscopic model matrix;

[0124] S104. On the basis of the three-dimensional random aggregate mesoscopic model obtained in S103, a preliminary grid size is set to obtain a preliminary grid model.

[0125] In this embodiment, the specific operation steps of step 2 are:

[0126] S201, export the preliminary mesh model obtained in S104 to Ansa software in inp format. In Ansa, first draw the outer surface of the preliminary mesh model into a triangular shell mesh, and define the body mesh according to the shell mesh. This can effectively save mesh division time and ensure mesh quality. The total number of model units is 1165108 and the total number of nodes is 254371. The aggregate unit type is C3D4T, the number of units is 263476, the number of nodes is 73745, and the concrete unit type is C3D4T, the number of units is 901632, and the number of nodes is 180626.

[0127] S202, define the aggregate elastic modulus as 41Gpa, Poisson's ratio as 0.3, specific heat capacity as 840J / (kg*℃), thermal expansion coefficient as 6E-6, and density as 1800kg / m 3 and thermal conductivity is 1.16W / (m 2*k); the elastic modulus of concrete is defined as 30Gpa, Poisson's ratio is 0.14, specific heat capacity is 970J / (kg*℃), thermal expansion coefficient is 1E-5, and density is 2400kg / m 3 and thermal conductivity is 1.28W / (m 2 *k).

[0128] S203. In the Ansa software, a concrete model is added to the preliminary mesh model so that the aggregate is embedded in the concrete and the mesh is re-divided, wherein the aggregate and the concrete model mesh share nodes to form a relatively fixed relationship, thereby forming a concrete material research model.

[0129] like Figure 2 and Figure 3 As shown, in this embodiment, the specific operation of step three is: the concrete material research model is simulated and embedded in the ground foundation pit, the four sides of the concrete material research model are fixed in the X and Y directions respectively, and the ground is fixed in the Z direction. The upper surface of the concrete material research model is impacted by high-speed airflow and forms an angle α with the upper plane of the concrete material research model. The initial temperature of the concrete material research model is set to 20°C, and the airflow impact can be simplified to the impact force P.

[0130] In this embodiment, the specific steps of step 4 include:

[0131] S401. Calculation of vertical airflow load: Decompose the impact force P into the vertical force P in the vertical direction. b and horizontal shear force f i , the impact force P is set to P = mv, m is the mass flow rate of the gas per second, which is 6.376 kg / s, and v is the effective discharge velocity of the gas flow; the vertical load P b =mvsinα;

[0132] S402, Concrete surface heat convection coefficient:

[0133] like Figure 4 As shown in the figure, the high-temperature and high-speed gas flow impacts the concrete wall, forming a serious dynamic-thermal shock effect. Fig.12 As shown in the figure, when the hot air flow acts on the concrete surface, positive pressure and aerodynamic shear force are generated, causing corresponding stress and strain in the concrete. At the same time, strong heat convection occurs between the concrete wall surface, and then the heat transfer is completed in the form of heat conduction inside the concrete. Due to the uneven concrete structure and the existence of original defects (pores), thermal stress and steam pressure will also be generated after the heat transfer is completed. The impact heat transfer of high-temperature and high-speed airflow includes heat convection between the hot airflow and the upper surface of the concrete and heat conduction inside the concrete;

[0134] like Figure 5As shown in the figure, on the fluid side, the cylindrical channel for discharging high-temperature and high-speed airflow is defined as the exhaust channel, and the heat transfer process between the hot airflow in the exhaust channel and the wall of the concrete material research model is regarded as the non-circular channel turbulent forced convection heat transfer, and its Nusselt number is calculated using the Gnielinski formula

[0135]

[0136] For gas

[0137]

[0138] Where l is the exhaust duct length; d is the exhaust duct equivalent diameter; f is the Darcy drag coefficient of turbulent flow in the exhaust duct; Re is the Reynolds number, Pr f is the Prandtl constant of the thermal flow;

[0139] Exhaust duct equivalent diameter

[0140] Where A is the cross-sectional area of ​​the hot air flow in the exhaust duct; C is the circumference of the exhaust duct, that is, the part of the exhaust duct wall that contacts the hot air flow;

[0141] f=(1.82lgRe-1.64) -2

[0142]

[0143] In the formula, ρ l is the fluid density; u ∞ is the incoming flow velocity; μ is the fluid dynamic viscosity, and μ = ρν; x is the characteristic length, that is, the equivalent diameter of the exhaust duct;

[0144]

[0145] Where ν is the fluid kinematic viscosity; a is the fluid thermal conductivity.

[0146] After Nu is determined, the convective heat transfer coefficient between the hot air flow and the exhaust duct wall can be obtained according to its definition formula;

[0147]

[0148] Where λ is the thermal conductivity of the fluid;

[0149] Combining the above formulas, we get

[0150]

[0151] Heat convection formula q=h|T f -T w |;

[0152] On the solid side of the exhaust duct, that is, inside the concrete, heat conduction mainly occurs, and heat flows from high temperature to low temperature. According to Fourier's law, the expression of heat flux density is:

[0153]

[0154] Where q is the heat flux in W / (m 2 ), λ is the thermal conductivity in W / (m·℃), T is the temperature in ℃;

[0155] Effective thermal conductivity of unsaturated concrete eff The relationship with temperature and pore water saturation is as follows

[0156]

[0157] In the above formula, d (T) is the thermal conductivity of concrete in a dry environment, and its expression is:

[0158] λ d (T) = λ d0 (1+A λ (T-T0))

[0159] Where T0 is the reference temperature, which is 298.15K; λ d0 Take 1.67W / mK; A λ Take -1.017×10 -3 K -1 ρ l is the density of water; ρ s is the density of concrete; n is the porosity of concrete;

[0160] In a three-dimensional Cartesian coordinate system, assuming that the temperature of a point inside the concrete is T, the heat transfer of the concrete material is isotropic λ = λ eff , the three-dimensional unsteady-state heat conduction differential equation inside the concrete structure without internal heat source is:

[0161]

[0162] Where, ρ is the density of concrete; c is the specific heat capacity of concrete at constant pressure;

[0163] The heat conduction differential equation is a mathematical expression that describes the common characteristics of the heat conduction process. In order to obtain the transient temperature field distribution of concrete, it is necessary to give the temperature distribution and thermal boundary conditions of the concrete at the initial moment according to the actual situation. For non-steady-state heat transfer, the initial conditions for concrete heat transfer calculation are:

[0164] T(x,y,z,0)=T0

[0165] Where, T ois the initial temperature of concrete;

[0166] The convection heat transfer coefficient h of the boundary surface between the fluid and the concrete and the temperature T of the hot air flow are known. f ,Right now:

[0167]

[0168] The temperature field of concrete is calculated by solving the convection heat transfer coefficient between the hot air flow and the exhaust duct wall (concrete) and loading it onto the concrete boundary surface as a thermal boundary condition.

[0169] S403, calculate the pore internal pressure: Figure 6 As shown, the saturated steam pressure P vs Calculated by the empirical formula given by Hyland and Wexler

[0170]

[0171] Where C8 = -5.8x10 3 , C9=1.3915,C 10 =-4.8640×10 2 , C 11 =4.1765×10 -5 , C 12 =-1.445,C 13 =6.5460, when T≧674.3K, P vs =22.09MPa;

[0172] S404. Calculation of aerodynamic shear force: The viscous force on the model surface needs to be obtained by summing the friction forces of all wall units, that is:

[0173]

[0174] Among them: F v is the total viscous force; f i is the viscous friction force of wall unit i; c fi is the viscous friction coefficient of wall unit i; Q Ai is the local dynamic pressure of wall unit i; A i is the area of ​​wall unit i;

[0175] The viscous friction coefficient c of element i fi The reference temperature method based on local flow field parameters is used for calculation, namely:

[0176]

[0177] ρ e 、u e , μe are the density, velocity and dynamic viscosity coefficient of the outer edge of the boundary layer, respectively, and x is the length of the streamline emanating from the leading edge of the plate;

[0178] Local dynamic pressure Q of unit i Ai is the dynamic pressure at reference temperature T:

[0179] Q Ai =0.5ρu e 2

[0180] Then the viscous friction force of unit i can be expressed as:

[0181]

[0182] The friction force f i The direction is the tangent of the streamline, which is the velocity direction of the local wall. Let the tangent unit vector be τ i =(τ x , τ y , τ z ) Friction force f of unit i i The three components in the rectangular coordinate system (x, y, z) are:

[0183] f ix =f i τ x

[0184] f iy =f i τ y

[0185] f iz =f i τ z

[0186] Therefore, the three components of the total viscous force on the surface can be expressed in the rectangular coordinate system as follows:

[0187]

[0188]

[0189]

[0190] S405. The concrete material research model is divided into the impact zone and the post-impact zone according to the impact area. The impact zone is defined as the airflow diversion area, where the airflow parameters change more dramatically, the dynamic impact and thermal shock effects are more prominent, and erosion damage is prone to occur; the post-impact zone is defined as the area after the airflow diversion, where the erosion damage is smaller, and the more significant is the thermal effect of the airflow on the concrete wall. At the same time, the working condition table is compiled as follows Figure 7 shown.

[0191] In this embodiment, in order to verify the rationality of the divided grid, the model is re-grid in Ansa, and after the shell grid is defined as an entity, the maximum unit size is reduced, and the calculation is performed. The results are compared with the model of the original grid. The total number of grids of the two re-drawn models is 1581518, the number of nodes is 271500, the total number of grids is 857861, and the number of nodes is 152256. The re-divided grid model is imported into Abaqus in inp format for calculation, the analysis type is set to transient heat conduction, and the working condition is set to impact zone loading. The maximum surface temperatures of the re-divided grid model are 282.3°C and 284.6°C, respectively, and the maximum surface temperature of the original grid is 283.1°C. The maximum surface temperature errors of the re-divided grid model and the original model are 0.28% and 0.53%, respectively. The result error is very small. Within the allowable range, the concrete surface temperature change curves of the three grid models are basically consistent with each other, which can be used to judge the rationality of the drawn grid.

[0192] In this embodiment, the specific steps of step five are:

[0193] S501. The calculation results in step 4 are divided into two parts. The first part is the stress cloud map, heat transfer depth, displacement cloud map, damage area and mass loss rate of the model under the impact of high-temperature airflow in the impact area and after the impact area; the second part is the stress cloud map, heat transfer depth, displacement cloud map, damage area and mass loss rate of the model when observing the changes of airflow impact angle, airflow temperature and airflow impact speed in the impact area;

[0194] S502. In the impact zone, the curves of aerodynamic shear force changing with time, vertical load changing with time, and heat convection coefficient changing with time are calculated according to the formula in step 4 as follows: Figures 8 to 10 Then the transient temperature field of the concrete material research model is calculated, and the aerodynamic shear force, vertical load and thermal convection coefficient data are imported into the calculation and analysis to obtain the temperature inside the pores. Figures 11 to 13 It can be seen that the temperature propagation depth is 4.34mm, accounting for about 8.68% of the total length. The temperature inside the pores is the maximum surface temperature of the concrete material research model, 283.1℃. According to the calculation formula of the saturated steam internal pressure of the pores, it can be calculated that the internal pressure of the pores is about 6Mpa. The heat-solid coupling field is established by the internal pressure of the pores and the pore temperature to obtain the stress cloud map. The angle between the high-temperature airflow and the upper surface of the foundation pit is 26°. The maximum equivalent stress on the concrete surface is 120.3MPa, which is mainly distributed in the pore area. The maximum equivalent displacement of the model is 0.0086mm. According to GB50010-2010 "Concrete Structure Design Code", the concrete compressive strength F of C30 is specified. ck =20.1MPa, F tk=2.01Mpa, remove the failed unit, and the model stress cloud diagram is shown in Figure 14. In the Abaqus post-processing, the failed unit is removed, and the model stress cloud diagram is shown in the figure above. The mass loss rate is 8.58% after the mass measurement of the removed failed unit. Similarly, the volume of the failed unit is measured in Abaqus, and divided by the surface area of ​​the concrete, the average depth of the surface peeling layer is 4.29mm. According to GB50010-2010 "Concrete Structure Design Code", the concrete compressive strength of C25 is Fck=16.7MPa, Ftk=1.78Mpa, the concrete compressive strength of C35 is Fck=23.4MPa, Ftk=2.20Mpa, and the concrete compressive strength of C40 is Fck=23.4MPa, Ftk=2.20Mpa. ck =26.8.4MPa, F tk =2.39Mpa. The mass of the removed failed units was measured in Abaqus, and the mass loss rate of C25 was 9.44%, the mass loss rate of C35 was 7.75%, and the mass loss rate of C40 was 7.11%. By comparison, it was found that C25 had the largest mass loss rate and the largest average depth of the detached layer, while C40 had the smallest mass loss rate and the smallest average depth of the detached layer.

[0195] The analysis results in Abaqus show that the total time is 5.17s, and the incremental steps are automatically divided into 9 steps. During the simulation calculation, at 0.1s, the model surface did not fall off, and at 0.2s, the model surface began to fall off, and the falling volume accounted for 0.87%. From the concrete surface morphology at 0.2s, it can be seen that the falling parts are mainly concentrated near the pores and aggregates. Fig.15 From the curve, we can see that within 0.2s to 0.5s, the slope of the curve is larger, and the concrete surface falls off fastest. The main reason is that the temperature of the high-temperature airflow is highest between 0.2s and 0.5s, which makes the thermal stress on the concrete surface grow at a high rate within the range of 0.2s to 0.5s, exceeding the compressive and tensile strength limits, resulting in the destruction and falling off of the surface concrete and aggregate.

[0196] S503. After the impact zone, the steps are the same as S502, and the heat transfer depth is 4.13 mm, accounting for about 8.26% of the total length. The temperature inside the pores is about 242.3 °C, the pressure inside the pores is about 4 MPa, the maximum equivalent stress on the concrete surface is 102.40 MPa, the mass loss rate is 6.62%, and the average depth of the surface peeling layer is 3.31 mm.

[0197] S504. Prepare a summary comparison table of the calculation results of the impact zone and after the impact zone. Fig.16 shown.

[0198] S505. In the impact zone, the impact angle, temperature and speed of the high-temperature and high-speed airflow are changed by the control variable method, and the loss degree of the impact zone under different conditions is calculated respectively. The specific process is that when studying the impact zone, a decoupled simulation of a single factor change is used, that is, when one variable changes, the other variables are all constants:

[0199] S5051, when the angle is 18°, different impact angles only affect the size of the vertical load, and the maximum equivalent displacement of the model is 0.0087mm. According to GB50010-2010 "Concrete Structure Design Code", the concrete compressive strength F of C30 ck =20.1MPa, F tk =2.01Mpa, remove the failed unit, remove the failed unit in Abaqus, measure the mass of the removed failed unit, and get a mass loss rate of 8.57%. Similarly, measure the volume of the failed unit in Abaqus, and divide it by the surface area of ​​the concrete to get an average depth of 4.29mm for the surface peeling layer; when the angle is 60°, the maximum equivalent displacement is 0.0084mm, the mass loss rate is 8.56%, and the average depth is 4.29mm; when the angle is 90°, the maximum equivalent displacement is 0.0083mm, the mass loss rate is 8.55%, and the average depth is 4.28mm. When the impact airflow angle is 26°, the vertical displacement shows that the vertical downward displacement on the right side is larger, and the vertical upward displacement on the left side is larger. The reason is that the concrete is impacted by the airflow at an angle of 26° to its surface, so there will be this phenomenon. With the change of time, the vertical downward displacement on the right side of the concrete model gradually decreases, and the vertical upward displacement on the left side gradually increases. The reason is that the concrete model is impacted by the high-temperature airflow and the model as a whole has thermal expansion phenomenon. In addition, the airflow load at an angle of 26° to the concrete plane causes the vertical displacement of the left side of the model to gradually increase, and the displacement on the right side to gradually decrease. The summary table of the results of the impact zone at different impact angles is drawn Fig.17 .

[0200] S5052. The change of high-temperature and high-speed airflow temperature will affect the heat transfer coefficient of concrete surface convection, aerodynamic shear force, and saturated steam pressure of pores. Each load needs to be substituted into the formula for recalculation. When the airflow temperature is 760℃, the heat transfer depth is 3.8mm, accounting for about 7.6% of the total length, the temperature in the pore is about 229.90℃, and the pressure in the pore is about 2.5Mpa. Abaqus removes the failed unit, and the model stress cloud diagram is shown in the figure above. The mass of the removed failed unit is measured, and the mass loss rate is 6.72%. The volume of the failed unit is also measured in Abaqus, divided by the surface area of ​​the concrete, and the average depth of the surface shedding layer is 3.36mm. When the airflow temperature is 900℃, the heat transfer depth is 3.9mm, accounting for about 7.8% of the total length, the temperature in the pore is about 269.60℃, the pressure in the pore is about 3.75Mpa, the mass loss rate is 6.90%, and the average depth of the surface shedding layer is 3.45mm. When the air flow temperature is 1100℃, the heat transfer depth is 4.0mm, accounting for about 8% of the total length, the temperature inside the pore is about 326.4℃, the internal pressure of the pore is about 15Mpa, the mass loss rate is 7.63%, and the average depth of the surface shedding layer is 3.82mm. When the air flow temperature is 2200℃, the heat transfer depth is 4.1mm, accounting for about 8.2% of the total length, the temperature inside the pore is about 638.40℃, the internal pressure of the pore is about 22.05Mpa, the mass loss rate is 10.17%, and the average depth of the surface shedding layer is 5.09mm. When the temperature is 2500℃, the heat transfer depth is 4.2mm, accounting for about 8.4% of the total length, the temperature inside the pore is about 638.40℃, the internal pressure of the pore is about 22.05Mpa, the mass loss rate is 10.17%, and the average depth of the surface shedding layer is 5.09mm. Draw a summary table of the results of the impact zone at different impact gas temperatures Fig.19 , and the influence curve of air flow temperature on the average depth of the shedding layer is obtained Fig.18 , the relationship between the average depth of the exfoliation layer and time at different temperatures, from Fig.18 It can be seen that when the air flow temperature is 2500℃ and 2200℃, and the time is from 0s to 0.3s, the depth of the detached layer increases fastest with time, and then tends to be gentle. The main reason is that from 0s to 0.3s, the convective heat transfer coefficient continues to increase, and after 0.3s, the convective heat transfer coefficient gradually decreases. The concrete surface temperature growth rate is high first and then low, and the corresponding thermal stress growth rate also shows a trend of high first and then low, which directly affects the detachment speed of the failure unit on the concrete surface. Fig.18It can be seen that at the same time, the higher the airflow temperature, the greater the average depth of the detached layer. The higher the temperature, the higher the corresponding concrete surface temperature, the larger the corresponding strain of the surface thermal stress of the model, and the greater the degree of detachment of the detached layer. The concrete surface was analyzed locally. Under the impact of the airflow at 1100°C, the morphology and stress of the concrete surface began to change with the change of time. Slight peeling began at 0.2s. The green part leaked out was the aggregate, and the small holes below were the pores. As time went on, the shapes of the aggregates and pores changed significantly, the pores gradually became smaller, the aggregate detached parts became more, and the stress continued to increase. When the stress value reached the tensile and compressive strength of the concrete, the concrete began to fail, and the thickness of the detached layer continued to increase.

[0201] S5053. With the change of impact velocity, the heat transfer coefficient of concrete surface convection, high temperature airflow load, pore saturated steam pressure, and aerodynamic shear force will all change. Each load needs to be recalculated according to the formula. Fig.21 As shown, when the speed is 382m / s, the temperature propagation depth is 3.9mm, accounting for about 7.8% of the total length, the temperature in the pores is about 174.00℃, the pressure in the pores is about 0.25Mpa, the mass loss rate is 6.08%, and the average depth of the surface shedding layer is 2.97mm. When the speed is 790m / s, the temperature propagation depth is 4.05mm, accounting for about 8.1% of the total length, the temperature in the pores is about 284.70℃, the pressure in the pores is about 6Mpa, the mass loss rate is 7.40%, and the average depth of the surface shedding layer is 3.64mm. When the speed is 1770m / s, the temperature propagation depth is 4.2mm, accounting for about 8.4% of the total length, the temperature in the pores is about 455.3℃, the pressure in the pores is about 22.05Mpa, the mass loss rate is 10.00%, and the average depth of the surface shedding layer is 4.90mm. When the speed is 2000m / s, the temperature propagation depth is 4.275mm, accounting for about 8.55% of the total length, the temperature in the pores is about 479.00℃, the pressure in the pores is about 22.05Mpa, the mass loss rate is 10.17%, and the average depth of the surface shedding layer is 4.97mm. When the speed is 2200m / s, the temperature propagation depth is 3.9mm, accounting for about 7.8% of the total length, the temperature in the pores is about 498.2℃, the pressure in the pores is about 22.05Mpa, the mass loss rate is 10.34%, and the average depth of the surface shedding layer is 5.07mm. The comprehensive curve of the influence of airflow velocity on mass loss rate Fig. 20 , the relationship between the mass loss rate at different speeds and time, from Fig. 20It can be seen that the mass loss rate growth rate is large from 0s to 0.5s, and the mass loss rate growth rate tends to be flat after 1s, mainly because the impact airflow temperature grows faster from 0s to 0.5s, and then tends to be flat. The growth of airflow temperature will directly affect the thermal stress on the surface of the model. The higher the temperature, the greater the thermal stress. Too much thermal stress will exceed the tensile strength and compressive strength of the model, resulting in failure and shedding of the concrete surface. At the same time, as the airflow speed increases, the mass loss rate will also increase. The main reason is that the impact speed of the airflow mainly affects the convective heat transfer coefficient and the pore internal pressure. According to the formula, the greater the impact speed, the greater the convective heat transfer coefficient of the concrete surface. The increase in the convective heat transfer coefficient directly leads to an increase in the surface temperature of the model, and the corresponding thermal stress and pore internal pressure will also increase. The unit with thermal stress exceeding the C30 concrete strength value is considered a failed unit.

[0202] In summary, the following conclusions can be drawn:

[0203] (1) Because the impact velocity and temperature in the impact zone are the largest, the velocity will lead to an increase in the convective heat transfer coefficient, an increase in the aerodynamic shear force, and an increase in the pore internal pressure, while the temperature will lead to an increase in the convective heat transfer coefficient and an increase in the pore internal pressure, which will lead to an increase in the equivalent stress of the analysis results;

[0204] (2) Although the impact angle in the impact zone changes, the heat flow temperature of the overall impact surface is basically the same, and the pore internal pressure of the model is basically the same. The change in the impact zone angle mainly affects the magnitude of the vertical load. Compared with the thermal stress of the model, the stress generated by the vertical load can be basically ignored, so the equivalent stress, displacement, and mass loss rate of the model surface are basically the same.

[0205] (3) As the air flow temperature in the impact zone increases, the thermal convection coefficient and the pore internal pressure increase, and the equivalent stress and equivalent displacement of the corresponding model increase, as well as the mass loss rate.

[0206] (4) As the air flow velocity in the impact zone increases, the aerodynamic shear force and thermal convection coefficient will increase, the pore internal pressure will also increase accordingly, and the equivalent stress, equivalent displacement, and mass loss rate of the model will increase accordingly.

[0207] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A damage assessment method for concrete material eroded by high-temperature and high-speed airflow, characterized in that: The following steps are involved: Step 1: Use Digmat-FE software to establish the concrete material model to be evaluated, and perform mesh division to obtain a preliminary mesh model of the concrete material; Step 2: Refine the preliminary mesh model of concrete material obtained in step 1 in ANSA software to obtain a concrete material research model; Step 3: Load high-temperature and high-speed airflow to the concrete material research model obtained in step 2 in Abaqus software; Step 4: Calculate the vertical airflow load, concrete surface heat convection coefficient, pore internal pressure and aerodynamic shear force of the loaded concrete material research model; Step 5: According to the calculation results in step 4, the transient thermal-solid coupling calculation of the concrete material research model is performed in the Abaqus software to obtain the stress cloud map of the concrete material research model, and then the heat transfer depth, displacement cloud map, damage area and mass loss rate are calculated to determine the damage degree of the concrete material eroded by the high-temperature and high-speed airflow; The specific steps of establishing the preliminary mesh model of concrete material by Digmat-FE software in step 1 are as follows: S101. A three-dimensional random aggregate mesoscopic model of concrete material is established in Digmat-FE software. The aggregate in the random aggregate mesoscopic model is in the shape of an ellipsoid and contains ellipsoidal pores. S102, setting the volume fraction of aggregate in the aggregate mesoscopic model to 70%, the major axis size of the aggregate to 5-20 mm, setting the volume fraction of pore in the aggregate mesoscopic model to 1%, and the major axis size of the pore to 1-5 mm; S103, setting the pores and the aggregate model to have a certain gap and not overlap, and all of them are randomly distributed in the three-dimensional random aggregate mesoscopic model matrix; S104, setting a preliminary grid size based on the three-dimensional random aggregate mesoscopic model obtained in S103 to obtain a preliminary grid model; The specific operation steps of step 2 are: S201, exporting the preliminary mesh model obtained in S104 to Ansa software in inp format; S202. Define the elastic modulus, Poisson's ratio, specific heat capacity, thermal expansion coefficient, density and thermal conductivity of aggregate and concrete; S203, adding a concrete model to the preliminary mesh model in the Ansa software so that the aggregate is embedded in the concrete and the mesh is re-divided, wherein the aggregate and the concrete model meshes share nodes to form a relatively fixed relationship, thereby forming a concrete material research model; The specific operation of step three is: the concrete material research model is simulated and embedded in the ground foundation pit, the four sides of the concrete material research model are fixed in the X and Y directions respectively, the ground is fixed in the Z direction, the upper surface of the concrete material research model is impacted by the high-speed airflow and forms an angle α with the upper plane of the concrete material research model, the initial temperature of the concrete material research model is set to 20°C, and the airflow impact can be simplified to the impact force P; The specific steps of step 4 include: S401. Calculation of vertical airflow load: Decompose the impact force P into the vertical force P in the vertical direction. b and horizontal shear force f i , the impact force P is set to P = mv, m is the mass flow rate of gas per second, m is 6.376 kg / s, v is the effective discharge velocity of the gas flow; the vertical load P b =mvsinα; S402. Calculate the heat convection coefficient of the concrete surface: The impingement heat transfer of high-temperature and high-speed airflow includes heat convection between the hot airflow and the upper surface of the concrete and heat conduction inside the concrete. On the fluid side, the cylindrical channel for discharging high-temperature and high-speed airflow is defined as the exhaust channel. The heat transfer process between the hot airflow in the exhaust channel and the wall of the concrete material research model is regarded as non-circular channel turbulent forced convection heat transfer, and its Nusselt number is calculated using the Gnielinski formula: For gas In formula (1), l is the exhaust duct length; d is the exhaust duct equivalent diameter; f is the Darcy drag coefficient of turbulent flow in the exhaust duct; Re is the Reynolds number, Pr f is the Prandtl constant of the thermal flow; Exhaust duct equivalent diameter In formula (3), A is the cross-sectional area of ​​the hot air flow in the exhaust duct; C is the circumference of the exhaust duct, that is, the part of the exhaust duct wall in contact with the hot air flow; f=(1.82lgRe-1.64) -2 (4) In formula (5), ρ l is the fluid density; u ∞ is the incoming flow velocity; μ is the fluid dynamic viscosity, and μ = ρν; x is the characteristic length, that is, the equivalent diameter of the exhaust duct; In formula (6), ν is the fluid kinematic viscosity; ɑ is the fluid thermal conductivity; After Nu is determined, the convective heat transfer coefficient between the hot air flow and the exhaust duct wall can be obtained according to its definition formula; In formula (7), λ is the thermal conductivity of the fluid; Combining equations (1) to (7), we get: Heat convection formula q=hT f -T w |; On the solid side of the exhaust duct, that is, inside the concrete, heat conduction mainly occurs, and heat flows from high temperature to low temperature. According to Fourier's law, the expression of heat flux density is: In formula (8), q is the heat flux density in W / (m 2 ), λ is the thermal conductivity in W / (m·℃), T is the temperature in ℃; Effective thermal conductivity of unsaturated concrete eff The relationship with temperature and pore water saturation is as follows: In formula (9), d (T) is the thermal conductivity of concrete in a dry environment, and its expression is: λ d (T)=λ d0 (1+A λ (T-T0)) (10) In formula (10), T0 is the reference temperature, which is 298.15K; λ d0 Take 1.67W / mK; A λ Take -1.017×10 -3 K -1 ρ l is the density of water; ρ s is the density of concrete; n is the porosity of concrete; In a three-dimensional Cartesian coordinate system, assuming that the temperature of a point inside the concrete is T, the heat transfer of the concrete material is isotropic λ = λ eff , the three-dimensional unsteady-state heat conduction differential equation inside the concrete structure without internal heat source is: In formula (11), ρ is the density of concrete; c is the specific heat capacity of concrete at constant pressure; The heat conduction differential equation is a mathematical expression that describes the common characteristics of the heat conduction process. In order to obtain the transient temperature field distribution of concrete, it is necessary to give the temperature distribution and thermal boundary conditions of the concrete at the initial moment according to the actual situation. For non-steady-state heat transfer, the initial conditions for concrete heat transfer calculation are: T(x,y,z,0)=T0 (12) In formula (12), T o is the initial temperature of concrete; The convection heat transfer coefficient h of the boundary surface between the fluid and the concrete and the temperature T of the hot air flow are known. f , then we can get: The temperature field of concrete is calculated by solving the convection heat transfer coefficient between the high-temperature and high-speed hot airflow and the exhaust duct wall of the concrete material and loading it onto the concrete boundary surface as the thermal boundary condition. S403. Calculate the internal pressure of the pores: saturated steam pressure P vs Calculated by the empirical formula given by Hyland and Wexler: In formula (13), C8 = -5.8x10 3 , C9=1.3915,C 10 =-4.8640×10 2 , C 11 =4.1765×10 -5 , C 12 =-1.445, C 13 =6.5460, when T≧674.3K, P vs =22.09MPa; S404. Calculation of aerodynamic shear force: The viscous force on the model surface needs to be obtained by summing the friction forces of all wall units, that is: In formula (14): F v is the total viscous force; f i is the viscous friction force of wall unit i; c fi is the viscous friction coefficient of wall unit i; Q Ai is the local dynamic pressure of wall unit i; A i is the area of ​​wall unit i; The viscous friction coefficient c of element i fi The reference temperature method based on local flow field parameters is used for calculation, namely: In formula (15), ρ e 、u e , μ e are the density, velocity and dynamic viscosity coefficient of the outer edge of the boundary layer, respectively, and x is the length of the streamline emanating from the leading edge of the plate; Local dynamic pressure Q of unit i Ai is the dynamic pressure at reference temperature T: Q Ai =0.5ρu e 2 Then the viscous friction force of unit i can be expressed as: Friction force f i The direction is the tangent of the streamline, that is, the velocity direction of the local wall. Let the tangent unit vector be τ i =(τ x , τ y , τ z ) Friction force f of unit i i The three components in the rectangular coordinate system (x, y, z) are: f ix =f i t x f iy =f i t y f iz =f i t z The total viscous force on the surface is then expressed in three components in the rectangular coordinate system: S405. Divide the concrete material research model into impact zones and impact areas according to different impact areas, and then compile a working condition table.

2. The damage assessment method for concrete material eroded by high-temperature and high-speed airflow according to claim 1 is characterized in that: The specific steps of step five are: S501. The calculation results in step 4 are divided into two parts. The first part is the stress cloud map, heat transfer depth, displacement cloud map, damage area and mass loss rate of the model under the impact of high-temperature airflow in the impact area and after the impact area; the second part is the stress cloud map, heat transfer depth, displacement cloud map, damage area and mass loss rate of the model when observing the changes of airflow impact angle, airflow temperature and airflow impact speed in the impact area; S502, respectively, in the impact zone and after the impact zone, calculate the curves of the aerodynamic shear force, vertical load and thermal convection coefficient changing with time according to the formula in step 4; then calculate the transient temperature field of the concrete material research model, import the aerodynamic shear force, vertical load and thermal convection coefficient data into the calculation and analysis to obtain the temperature inside the pores, the temperature inside the pores is the maximum temperature of the surface layer of the concrete material research model, establish a heat-solid coupling field based on the pore internal pressure and pore temperature to obtain a stress cloud map, then remove the failed unit and measure the mass of the failed unit to obtain the mass loss rate of the concrete material research model, measure the volume of the failed unit, divide the volume of the failed unit by the concrete surface area to obtain the average depth of the surface peeling layer, and finally obtain a comparison of the degree of damage of concrete of different grades by setting the compressive strength standard of different concrete grades; S503, in the impact zone, changing the impact angle, temperature and speed of the high-temperature and high-speed airflow by the control variable method, and calculating the loss degree of the impact zone under different conditions respectively, the calculation method is the same as the calculation method provided in S502; S504. Compare and analyze the calculation results obtained in S502 and S503 to draw conclusions on the damage of concrete materials under high-temperature and high-speed airflow erosion.

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