A concrete cave wall design method, system and medium under the action of gradient temperature difference

Abstract

The invention discloses a concrete cave wall design method, system and medium under the action of gradient temperature difference; it relates to the technical field of wind tunnel construction; the scheme constructs a first wind tunnel concrete cave wall model in finite element analysis software based on a first basic boundary condition, meshes the first wind tunnel concrete cave wall model, applies a gradient temperature difference load to each grid, and solves the first cave wall stress; the design control stress is obtained by superimposing the first cave wall stress applying the gradient temperature difference load and the second cave wall stress applying the conventional load, and the cave wall temperature difference in different areas is superimposed into the design control stress, thereby ensuring the performance of a large-scale concrete cave wall structure in a gradient temperature difference environment; at the same time, the scheme also takes into account the uneven distribution of cave wall stress when performing reinforcement design, thereby ensuring the performance and safety of a large-scale concrete cave wall structure in a gradient temperature difference environment.

Description

Technical Field

[0001] The invention relates to the technical field of wind tunnel construction, and in particular to a concrete tunnel wall design method, system and medium under the action of gradient temperature difference. Background Art

[0002] The impact of temperature on structural design is related to the size of the structure and the size and range of the temperature effect. The larger the structure and the more complex the constraints, the more obvious the temperature effect. At present, domestic research on temperature effects is mostly focused on structural response under temperature changes, solar radiation and fire. In traditional design, the temperature difference of components in different positions is taken into account. For example, the temperature values ​​of the concrete floor and the upper steel roof are different, but the same component in the same position can only have one temperature value. For large-scale wind tunnels, there are obvious differences in their temperature distribution, that is, the temperature difference of the tunnel wall in different areas along the space temperature is small, but at the same spatial position, such as Figure 1 As shown in the figure, the temperature difference varies greatly within a small range along the thickness of the cave wall, and it is difficult for traditional design methods to accurately consider and propose safe, reliable and economical construction measures. Summary of the invention

[0003] The technical problem to be solved by the present invention is: for a large-scale wind tunnel, there are obvious differences in its temperature distribution, that is, the temperature difference of the tunnel wall in different areas along the spatial temperature is small, but at the same spatial position, the temperature difference in a small scale range along the thickness direction of the tunnel wall varies greatly, and it is difficult for traditional design methods to accurately consider and propose safe, reliable and economical construction measures; the purpose of the present invention is to provide a concrete tunnel wall design method, system and medium under the action of gradient temperature difference, and to improve the method on the basis of traditional concrete tunnel wall design technology; based on the first basic boundary condition, a first wind tunnel concrete tunnel wall model is constructed in a finite element analysis software, the first wind tunnel concrete tunnel wall model is gridded, and a gradient temperature difference load is applied to each grid to solve the first tunnel wall stress; the design control stress is obtained by superimposing the first tunnel wall stress applying the gradient temperature difference load and the second tunnel wall stress applying the conventional load, and the reinforcement design is performed considering the uneven distribution of the tunnel wall stress, thereby ensuring the performance and safety of the large-scale concrete tunnel wall structure in a gradient temperature difference environment.

[0004] The present invention is achieved through the following technical solutions:

[0005] This scheme provides a concrete cave wall design method under the action of gradient temperature difference, including:

[0006] Setting a first basic boundary condition and a second basic boundary condition;

[0007] A first wind tunnel concrete wall model is constructed in the finite element analysis software based on the first basic boundary condition, and a second wind tunnel concrete wall model is constructed in the structural design software based on the second basic boundary condition;

[0008] The concrete wall model of the first wind tunnel is meshed, and a gradient temperature difference load is applied to each mesh to solve the first wall stress; conventional loads are applied to the concrete wall model of the second wind tunnel to solve the second wall stress;

[0009] The first cave wall stress and the second cave wall stress are superimposed to obtain the design control stress;

[0010] The concrete cavity wall is reinforced according to the design control stress.

[0011] Working principle of this scheme: For large-scale wind tunnels, there are obvious differences in their temperature distribution, that is, the temperature difference of the tunnel wall in different areas along the spatial temperature is small, but at the same spatial position, the temperature difference in a small scale range along the thickness direction of the tunnel wall varies greatly. It is difficult for traditional design methods to accurately consider and propose safe, reliable and economical construction measures; This scheme provides a concrete tunnel wall design method under the action of gradient temperature difference; On the basis of traditional concrete tunnel wall design technology, the method is improved; By constructing the first wind tunnel concrete tunnel wall model in the finite element analysis software based on the first basic boundary condition, the first wind tunnel concrete tunnel wall model is meshed, and a gradient temperature difference load is applied to each grid to solve the first tunnel wall stress; By superimposing the first tunnel wall stress with the gradient temperature difference load and the second tunnel wall stress with the conventional load to obtain the design control stress, the temperature stress generated by the tunnel wall temperature difference in different areas is superimposed into the design control stress, which ensures the performance of the large-scale concrete tunnel wall structure in the gradient temperature difference environment. At the same time, this scheme also considers the uneven distribution of tunnel wall stress when designing the reinforcement, ensuring the performance and safety of the large-scale concrete tunnel wall structure in the gradient temperature difference environment.

[0012] A further optimization scheme is that the method for setting the first basic boundary condition includes:

[0013] The foundation stiffness of the wind tunnel concrete wall is solved based on the M-value method;

[0014] Based on the foundation stiffness, the parameters of the foundation short columns of the wind tunnel concrete wall are determined in combination with the equivalent stiffness method: multiple sections of non-laterally constrained cylinders are established at the bottom of the wind tunnel concrete wall to simulate the foundation stiffness, and fixed constraints are performed at the bottom of each non-laterally constrained cylinder; the parameters of the non-laterally constrained cylinders are solved as the parameters of the foundation short columns.

[0015] A further optimization scheme is that the parameter solution method of the cylinder without lateral constraints includes:

[0016] A single pile model corresponding to the real project is established, and the diameter of the single pile in the single pile model is set to d, and the total length of the single pile does not exceed 6d;

[0017] The single pile model is divided into n sections of sub-piles with a length of L at equal intervals, where n≥10; a bidirectional spring constraint is applied laterally to each section of the sub-pile; the stiffness k of the bidirectional spring constraint is k = m * L * h, where m represents the proportional coefficient of the horizontal resistance coefficient of the foundation soil, and h is the distance from the bidirectional spring to the top of the single pile;

[0018] Obtain the single pile deformation coefficient δ of the single pile model under unit force F, and calculate the diameter D of the cylinder without lateral constraints according to the following formula:

[0019] F / (3EI / H 3 ) = δ;

[0020] I = π * D 4 / 64;

[0021] Where E is the elastic modulus, I is the section moment of inertia, and H is the length of the cylinder without lateral constraints.

[0022] A further optimization scheme is that the first wind tunnel concrete wall model is constructed in the finite element analysis software based on the first basic boundary condition, including the following method:

[0023] A first wind tunnel concrete wall model is constructed based on ABAQUS software, wherein the first wind tunnel concrete wall model includes: a concrete cave body part, a steel structure grid part, a top plate steel beam part, a hanger part and a support part;

[0024] The concrete cave part is constructed by the solid unit C3D8R model; the steel structure grid part is constructed by the truss unit T3D2 model; the top plate steel beam part, the hanger part and the support part are all constructed by the beam unit B31 model;

[0025] The uniaxial constitutive relationship of concrete is constructed based on the mender uniaxial constitutive model; the multiaxial constitutive model of steel is constructed based on the classical plastic metal plasticity model; and the uniaxial constitutive relationship is constructed based on the biaxial line model.

[0026] A further optimization scheme is that the first wind tunnel concrete wall model is constructed in the finite element analysis software based on the first basic boundary condition, and also includes a method:

[0027] The constraint condition of the support part is realized by the constraint of the cylinder without lateral constraint; specifically, the bottom of the cylinder without lateral constraint is a fixed constraint, and the top of the cylinder without lateral constraint is connected to the hole wall;

[0028] The constraint conditions of the top plate steel beam part are realized by embedded constraints;

[0029] The constraints of the support part and the concrete cavity part are all realized by MPC-beam constraints. At the same time, the constraints of the support part include: the outer support is rigidly connected and the inner support is hinged.

[0030] A further optimization scheme is that the meshing of the first wind tunnel concrete wall model includes the following method:

[0031] Perform non-uniform meshing on the concrete wall model of the first wind tunnel:

[0032] The concrete cavern is uniformly divided into N×N grids, N≤H / 4; H represents the thickness of the concrete cavern, and the sidewall and top plate of the concrete cavern are uniformly divided into M×M grids; M∈(1N / 4, 1N / 2);

[0033] Divide each rod of the steel structure grid into a grid;

[0034] The top plate steel beam part, the hanger part and the support part are evenly divided into a 2.5N×2.5N grid.

[0035] A further optimization scheme is to apply a gradient temperature difference load to each grid to solve the first cave wall stress, including the following method:

[0036] The concrete wall model of the first wind tunnel is divided into multiple structural monomers according to the structural joints: the structure between every two structural joints is regarded as a structural monomer;

[0037] Screening out typical structural monomers; the typical structural monomers are representative structural monomers screened out from multiple structural monomers of the same type;

[0038] Obtain the temperature distribution of the wind tunnel concrete wall, apply gradient temperature difference loads to the grids of each typical structural unit, and calculate the temperature stress of each typical structural unit based on the static general solver combined with the material thermodynamic parameters;

[0039] Based on the temperature stress of each typical structural monomer, the temperature stress of all structural monomers is merged to obtain the first cave wall stress.

[0040] A further optimization scheme is that the concrete cavity wall reinforcement is performed according to the design stress control method, including the following method:

[0041] Obtain the design control stress, and consider the uneven distribution of the cave wall stress, and reinforce the concrete cave wall in an asymmetrically designed reinforcement form or with additional steel plates:

[0042] For the asymmetric reinforcement design, if the temperature rise inside the concrete cavity wall exceeds the temperature rise outside the cavity and reaches the preset first temperature threshold, the number of reinforcements outside the cavity is greater than the number of reinforcements inside the cavity;

[0043] For the reinforcement form of additional steel plates, if the temperature inside the concrete cavity wall exceeds the temperature outside the cavity and reaches a preset second temperature threshold, additional steel plates are added to the outside of the cavity.

[0044] The present invention also provides a concrete cave wall design system under the action of gradient temperature difference, which is used to implement the above-mentioned concrete cave wall design method under the action of gradient temperature difference; the system comprises:

[0045] A configuration module, used for setting a first basic boundary condition and a second basic boundary condition;

[0046] A construction module, used to construct a first wind tunnel concrete wall model in a finite element analysis software based on a first basic boundary condition, and to construct a second wind tunnel concrete wall model in a structural design software based on a second basic boundary condition;

[0047] A solution module is used to mesh the first wind tunnel concrete wall model and apply a gradient temperature difference load to each grid to solve the first wall stress; the solution module is also used to apply a conventional load to the second wind tunnel concrete wall model to solve the second wall stress;

[0048] A superposition module, used for superimposing the first cave wall stress and the second cave wall stress to obtain the design control stress;

[0049] The adjustment module is used to carry out concrete cavity wall reinforcement according to the design control stress.

[0050] The present solution also provides a computer-readable medium on which a computer program is stored. The computer program is executed by a processor to implement the above-mentioned method for designing a concrete cave wall under the action of a gradient temperature difference.

[0051] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0052] 1. The present invention provides a method, system and medium for designing a concrete cave wall under the action of a gradient temperature difference. On the basis of the traditional concrete cave wall design technology, the method is improved. A first wind tunnel concrete cave wall model is constructed in a finite element analysis software based on a first basic boundary condition, the first wind tunnel concrete cave wall model is meshed, and a gradient temperature difference load is applied to each grid to solve the first cave wall stress. The design control stress is obtained by superimposing the first cave wall stress with the gradient temperature difference load and the second cave wall stress with the conventional load, thereby ensuring the performance of a large-scale concrete cave wall structure under a gradient temperature difference environment.

[0053] 2. The present invention provides a method, system and medium for designing concrete cave wall under the action of gradient temperature difference. The uneven stress distribution of the cave wall is also taken into consideration during the reinforcement design. According to the characteristics of the cave wall stress distribution, an asymmetric reinforcement design or an additional steel plate is adopted on the outer side of the cave wall. This reinforcement design specifically enhances the tensile strength of the structure while avoiding unnecessary waste of steel bars, thereby ensuring the performance and safety of large-scale concrete cave wall structures under gradient temperature difference environments.

[0054] 3. The present invention provides a method, system and medium for designing concrete cave wall under the action of gradient temperature difference. When setting the first basic boundary condition, a cylinder without lateral constraints is established to simulate the foundation stiffness, so that the interaction between the foundation short column and the cave wall structure is equivalently constructed in the modeling process, and the actual stress condition of the large-scale concrete cave wall structure is more realistically reflected. In particular, for temperature stress, which is an internal stress generated by constraints, the foundation stiffness is simulated by a cylinder without lateral constraints, so that the internal force and stress distribution of the cave wall structure under complex effects such as temperature gradient can be accurately analyzed, providing a reliable basis for structural design.

[0055] 4. The present invention provides a method, system and medium for designing concrete cave walls under gradient temperature difference, which can accurately calculate temperature stress based on a static general solver and material thermodynamic parameters, and can more accurately simulate the stress distribution of the cave wall under actual temperature, providing a more accurate basis for structural design. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0057] Figure 1 is the temperature distribution curve of the cave wall;

[0058] Figure 2 It is a flow chart of the concrete cave wall design method under the action of gradient temperature difference;

[0059] Figure 3 This is a schematic diagram of the design principle of the concrete cave wall under the action of gradient temperature difference;

[0060] Figure 4 Schematic diagram of the principle of determining the basic short column parameters;

[0061] Figure 5 This is a schematic diagram of the structure of the first wind tunnel concrete wall model;

[0062] Figure 6 This is a schematic diagram of the cylindrical structure without lateral constraints in the concrete wall model of the first wind tunnel;

[0063] Figure 7 This is a schematic cross-sectional view of the concrete wall model of the first wind tunnel;

[0064] Figure 8 Example 1 for asymmetric reinforcement design;

[0065] Fig. 9 Example 2 for asymmetric design of reinforcement form; DETAILED DESCRIPTION

[0066] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0067] For large-scale wind tunnels, there are obvious differences in their temperature distribution, that is, the temperature difference of the tunnel wall in different areas along the spatial temperature is small, but at the same spatial position, the temperature difference in a small scale range along the thickness direction of the tunnel wall varies greatly. Traditional design methods are difficult to accurately consider and propose safe, reliable and economical construction measures; in view of this, this solution provides the following embodiments to solve the above technical problems.

[0068] Embodiment 1: This embodiment provides a concrete cave wall design method under the action of gradient temperature difference, such as Figure 2 and Figure 3 As shown, including:

[0069] Step 1: Setting a first basic boundary condition and a second basic boundary condition; in step 1, the method for setting the first basic boundary condition includes:

[0070] S11, solve the foundation stiffness of the wind tunnel concrete wall based on the M-value method;

[0071] S12, based on the foundation stiffness, combined with the equivalent stiffness method, determine the foundation short column parameters of the wind tunnel concrete wall: establish multiple sections of non-laterally constrained cylinders at the bottom of the wind tunnel concrete wall to simulate the foundation stiffness, and perform fixed constraints on the bottom of each non-laterally constrained cylinder; solve the parameters of the non-laterally constrained cylinder as the foundation short column parameters.

[0072] When determining the parameters of the foundation short column, inputting the foundation stiffness based on the equivalent stiffness method plays an important role and has a significant effect. For large-scale concrete cave wall structures, the traditional column bottom foundation fully constrained boundary conditions cannot accurately reflect the actual situation. The equivalent stiffness method can more realistically simulate the interaction between the foundation short column and the concrete cave wall structure. Taking into account the actual geological conditions and the deformation characteristics of the foundation, the first foundation boundary condition is more in line with engineering reality.

[0073] In step S12, the method for solving the parameters of the cylinder without lateral constraints includes:

[0074] S121, establishing a single pile model corresponding to the real project, setting the diameter of a single pile in the single pile model to d, and the total length of the single pile to not more than 6d;

[0075] S122, dividing the single pile model into n sections of sub-piles with a length of L at equal intervals, where n≥10; applying a bidirectional spring constraint to each section of the sub-pile laterally; the stiffness k of the bidirectional spring constraint is k = m * L * h, where m represents a proportional coefficient of the horizontal resistance coefficient of the foundation soil, and h is a distance from the bidirectional spring to the top of the single pile;

[0076] S123, obtaining the single pile deformation coefficient δ of the single pile model under the unit force F, and calculating the diameter D of the cylinder without lateral constraints according to the following formula:

[0077] F / (3EI / H 3 ) = δ;

[0078] I = π * D 4 / 64;

[0079] Where E is the elastic modulus, I is the section moment of inertia, and H is the known length of the cylinder without lateral constraints.

[0080] This embodiment establishes a single pile model and sets a reasonable range of pile lengths to ensure that the single pile model can reflect the characteristics of the actual pile foundation within the progress range that meets the engineering requirements, while avoiding overly complex calculations caused by excessive pile lengths. The single pile is divided into equal intervals and a bidirectional spring constraint is applied, taking into account the influence of geological conditions on the pile foundation. The spring stiffness is determined by introducing the proportional coefficient m of the horizontal resistance coefficient of the foundation soil and the distance h from the bidirectional spring to the top of the single pile, so that the calculation is more in line with the actual geological conditions; the deformation of the pile top under unit force is calculated and the bending stiffness of the cylindrical section is inversely calculated, and the elastic modulus and the moment of inertia of the section are combined to finally solve the cylinder diameter D using the formula. This method provides an accurate calculation method for determining the size of the foundation simulation cylinder, which helps to more accurately simulate the interaction between the foundation short column and the concrete cave wall structure in the design of large-scale concrete cave wall structures, improve the accuracy and reliability of the structural design, and ensure that the structure can operate safely and stably under complex loads and temperature, avoiding structural internal force calculation deviations and potential safety risks caused by inaccurate foundation parameters.

[0081] like Figure 4 As shown, this embodiment simulates the foundation stiffness by establishing a cylinder without lateral constraints. In the modeling process, the interaction between the foundation short column and the cave wall structure is equivalently constructed, which more truly reflects the actual stress conditions of the large-scale concrete cave wall structure, especially the temperature stress, which is an internal stress generated by constraints. Using a cylinder without lateral constraints to simulate the foundation stiffness can accurately analyze the internal force and stress distribution of the cave wall structure under complex effects such as temperature gradient, and provide a reliable basis for structural design.

[0082] The second basic boundary condition mentioned above can be understood as the basic boundary condition constructed when constructing the concrete cave wall model by conventional methods.

[0083] Step 2: constructing a first wind tunnel concrete wall model in finite element analysis software based on the first basic boundary condition, and constructing a second wind tunnel concrete wall model in structural design software based on the second basic boundary condition;

[0084] In this step, the first wind tunnel concrete wall model is constructed in the finite element analysis software based on the first basic boundary condition, including the following method:

[0085] The concrete wall model of the first wind tunnel was constructed based on ABAQUS software. Figure 5 As shown in the figure, the cylindrical part without lateral constraints in the concrete wall model of the first wind tunnel is as follows Figure 6As shown in the figure, the concrete wall model of the first wind tunnel includes: a concrete cave body, a steel structure grid, a top plate steel beam, a hanger and a support. The concrete cave body is constructed by a solid unit C3D8R model. The solid unit C3D8R model can accurately simulate the continuous three-dimensional mechanical behavior of the concrete cave body, thereby considering its stress and strain distribution under various loads. The steel structure grid is constructed by a truss unit T3D2 model. The truss unit T3D2 model can effectively simulate the axial force characteristics of the rod structure, which is consistent with the characteristics that the grid structure mainly bears axial force. The top plate steel beam, the hanger and the support are all constructed by the beam unit B31 model. The beam unit B31 model can better reflect the force and deformation of the support in different directions, such as axial force, lateral force and rotation.

[0086] The uniaxial constitutive relationship of concrete is constructed based on the mender uniaxial constitutive model; the multiaxial constitutive model of steel is constructed based on the classical plastic metal plasticity model; and the uniaxial constitutive relationship is constructed based on the biaxial line model.

[0087] The constraint conditions of the support part are realized by the bidirectional spring constraint applied to the single pile; the constraint conditions of the top plate steel beam part are realized by the embedded constraint; the constraint conditions of the support part and the concrete cave part are both realized by the MPC-beam constraint. The MPC-beam constraint method can accurately simulate the connection relationship between the support and the cave wall to ensure the coordination of force transmission and deformation.

[0088] At the same time, the constraints of the support part include: the outer support is rigidly connected and the inner support is hinged.

[0089] Through the above settings, the mechanical behavior of the entire structure under various loads can be more realistically reflected, providing an accurate model basis for structural analysis and design, and ensuring the safety and reliability of the structure.

[0090] In this scheme, the second wind tunnel concrete wall model is constructed in the structural design software based on the second basic boundary condition, which mainly refers to constructing the wind tunnel concrete wall model in a traditional way, that is, using the traditional structural design software MIDAS to construct the wind tunnel concrete wall model;

[0091] Step 3: Mesh the first wind tunnel concrete wall model, apply gradient temperature difference load to each grid, and solve the first wall stress; apply conventional load to the second wind tunnel concrete wall model, and solve the second wall stress; in this step, mesh the first wind tunnel concrete wall model; including the method:

[0092] Considering the different stress characteristics and importance of different parts of the tunnel wall structure, the concrete wall model of the first wind tunnel is divided into uneven grids:

[0093] The side wall and top plate of the concrete cavern are the key analysis areas, and the gradient temperature difference varies greatly, so the grid division can be appropriately encrypted. Therefore, the side wall and top plate are evenly divided into M×M grids M∈(1N / 4, 1N / 2) (grid size is 50-100 mm); for the rest of the concrete cavern that is not directly subjected to the temperature gradient load, such as the wall surface, it can be evenly divided into N×N grids (grid size is 200 mm), N≤H / 4; H represents the thickness of the concrete cavern; for areas with a small gradient temperature difference, the grid size is coarser, and the grid is generally H / 6~H / 4 (grid size is 100 mm);

[0094] Divide each rod of the steel structure grid into a grid;

[0095] The top plate steel beam part, the hanger part and the support part are evenly divided into a 2.5N×2.5N grid with a grid size of 500mm.

[0096] The method of applying a gradient temperature difference load to each grid to solve the first cave wall stress includes:

[0097] S31, the cross-sectional diagram of the concrete wall model of the first wind tunnel is shown in Figure 7 As shown, the first wind tunnel concrete wall model is divided into a plurality of structural monomers according to the structural joints: the structure between every two structural joints is regarded as a structural monomer;

[0098] S32, screen out typical structural monomers; the typical structural monomers are representative structural monomers screened out from multiple structural monomers of the same type; for the fourth diffusion section-1, the fourth diffusion section-2, the fourth diffusion section-3, the fourth diffusion section-4 and the fourth diffusion section-5, which belong to the same type of structural monomers, the fourth diffusion section-3 is selected as the typical structural monomer; for the third corner section, the large open angle section and the fourth corner section, which belong to the same type of structural monomers, the combination of the large open angle section and the fourth corner section is selected as the typical structural monomer; the combination of the first corner section and the second diffusion section-1, the second diffusion section-2 and the second corner section belong to the same type of structural monomers, and the combination of the first corner section and the second diffusion section-1 is selected as the typical structural monomer; the full anechoic chamber itself is taken as the typical structural monomer.

[0099] Since the temperature effects between the same type of structural monomers and typical structural monomers are similar, the analysis results are also similar under similar temperature effects, so it is only necessary to perform detailed calculations using typical structural monomers.

[0100] S33, obtaining the temperature distribution of the wind tunnel concrete wall, and applying a gradient temperature difference load to the grid of each typical structural monomer, and calculating the temperature stress of each typical structural monomer based on a static general solver combined with material thermodynamic parameters;

[0101] Specifically, in ABAQUS software, the gradient temperature difference load is input by defining the Mapped field; the mapped field is a tool that can accurately describe the load distribution, through which complex temperature load distribution patterns can be input into the model. In order to more accurately realize the application of gradient temperature differences of different sizes at different positions on the cave wall, it is also necessary to combine local coordinates, geometric element division and loading predefined fields. Among them, local coordinates are used to determine the positions of points at different positions on the cave wall in the model. By defining appropriate local coordinates, the temperature load can be easily applied to a specific position on the cave wall; geometric element division is to further subdivide the geometric model of the cave wall. By dividing the cave wall into smaller geometric units, the application of temperature loads on different units can be more finely controlled; loading a predefined field is to load the temperature load defined by the mapped field to the corresponding area of ​​the model; by combining the above three methods, the application of gradient temperature differences of different sizes at different positions on the cave wall can be realized, so that the temperature load distribution is more in line with the actual situation.

[0102] S34, merging the temperature stresses of all structural monomers based on the temperature stresses of each typical structural monomer to obtain a first cave wall stress.

[0103] When the wind tunnel is working, the airflow heats up rapidly, causing the inner wall concrete structure to form a gradient temperature field with high inside and low outside. The temperature field will cause the structure to produce large temperature stress. After the wind tunnel stops working, the air temperature in the tunnel gradually drops to the ambient temperature until the next work, when the tunnel wall produces a gradient temperature field again. In the process of the structure returning to the ambient temperature, the stress on the tunnel wall is also released. Therefore, the focus of the analysis of the alternating temperature field is the impact of the gradient temperature field generated by the wind tunnel operation on the structure.

[0104] Therefore, in order to avoid excessive temperature effects caused by super-long structures, the wind tunnel body section is usually divided into several structural monomers through structural seams. When two structural monomers have similar structural arrangements, geometric dimensions and temperature effects, the component responses obtained from the structural analysis are basically the same. Therefore, typical structural monomers are selected from multiple structural monomers of the same type, and the temperature stresses of all structural monomers are merged based on the temperature stresses of each typical structural monomer. When performing temperature stress analysis, if each monomer is calculated separately, it will take a lot of time and cost. In order to improve efficiency, similar sections are merged through typical structural monomers to improve efficiency.

[0105] In step three, conventional loads are applied to the second wind tunnel concrete wall model to solve the second wall stress; the method includes: applying conventional loads to the constructed second wind tunnel concrete wall model in MIDAS software, and the conventional loads include dead loads, live loads, earthquake effects, long-term ambient temperature effects and wind loads.

[0106] Step 4: Superimpose the first cave wall stress and the second cave wall stress to obtain the design control stress;

[0107] The temperature field data "280MW fan input power, initial ambient temperature -3℃, corresponding index requirements: under all working conditions, continuous operation for 10 minutes, air flow temperature not higher than 60℃" were input into ABAQUS software to obtain the maximum temperature rise of the top plate to 26℃, the penetration depth was 63mm, the maximum temperature rise of the side wall to 36℃, the penetration depth was 170mm. Since a thermal insulation layer separated from the main structure is usually set on the upper surface of the bottom plate, the temperature effect caused by the wind tunnel operation will not directly affect the bottom plate, so no temperature effect is applied. The first cave wall stress calculated is superimposed on the second cave wall stress obtained by the traditional method to obtain the design control stress.

[0108] Step 5: Reinforce the concrete cavity wall according to the designed controlled stress.

[0109] This step specifically includes the following methods:

[0110] Obtain the design control stress, and consider the uneven distribution of the cave wall stress, and reinforce the concrete cave wall in an asymmetrically designed reinforcement form or with additional steel plates:

[0111] For asymmetric reinforcement design, if the temperature rise inside the concrete cavity wall exceeds the temperature rise outside the cavity and reaches the preset first temperature threshold, then Figure 8 As shown in , the number of reinforcements on the outside of the cavity is greater than that on the inside of the cavity; otherwise, Fig. 9 As shown in the figure, the number of reinforcements on the outside of the tunnel is less than or equal to the number of reinforcements on the inside of the tunnel;

[0112] For the reinforcement form of additional steel plates, if the temperature inside the concrete cavity wall exceeds the temperature outside the cavity and reaches a preset second temperature threshold, additional steel plates are added to the outside of the cavity.

[0113] According to the design control stress, the inner concrete is under compression and the outer concrete is under tension. The overall component presents a stress distribution characteristic that is completely different from the overall temperature rise. Therefore, the horizontal stress of the side wall is divided into 4 reinforcement areas, namely the half rib wall spacing area on the left and right sides of the side wall, the large face value and stress concentration value in the upper 3 / 4 of the middle area of ​​the side wall, and the lower 1 / 3 of the middle area of ​​the side wall. According to the obtained side wall horizontal section stress cloud map, the side wall horizontal reinforcement calculation table as shown in Table 1 is obtained:

[0114] Table 1 Calculation table of horizontal reinforcement of side wall

[0115]

[0116] The above reinforcement results are combined with the reinforcement results calculated by traditional structural design software. This embodiment is illustrated by the BB section of the middle side wall of DT-3. The specific reinforcement method is as follows:

[0117] The reinforcement after considering the ultimate bearing capacity state, elasticity in moderate earthquakes, unyielding in large earthquakes, ultimate bearing capacity state considering fatigue stiffness reduction, serviceability limit state and fatigue design factors in traditional design is as follows: the horizontal reinforcement of the side wall can be d14@200(1)(outer wall)+d12@200(1)(inner wall)+d14@200(1)(inner wall), and the vertical reinforcement is d14@200(1)(outer wall)+d12@300(1)(inner wall)+d14@200(1)(inner wall), where d12@200(1)(inner wall) and d12@300(1)(inner wall) are structural reinforcements that are not included in the calculation results. d14@200(1) means that a steel bar with a diameter of 14 is used, and one is set every 200; d12@300(1) It means that 12-diameter steel bars are used, with one set every 300 meters; the inner wall refers to the side of the cave wall that is in direct contact with the test airflow, and the outer wall refers to the side of the cave wall that is in contact with the atmospheric environment.

[0118] The additional steel reinforcement under the combined effect of air flow gradient temperature difference and ambient temperature is d22@100, and the actual reinforcement area is 3800 mm 2 >3333mm 2 (The required reinforcement area is calculated for the BB section). The final reinforcement is: d14@200+d22@100 on the outside of the tunnel wall, d12@200 on the inside of the tunnel wall, and d14@200 on the inside of the tunnel wall.

[0119] In summary, according to the combined results of internal forces and the characteristics of the stress distribution of the cave wall, the reinforcement is adjusted. If an asymmetric reinforcement design or additional steel plates are required, the reasonable configuration of the outer and inner reinforcements is determined so that it can meet the combined internal force requirements and meet the principles of economy and safety. Then, the adjusted reinforcement scheme is combined with the reinforcement scheme in the traditional structural design software to obtain the final reinforcement design result.

[0120] Embodiment 2: This embodiment provides a concrete cave wall design system under the action of gradient temperature difference, which is used to implement the concrete cave wall design method under the action of gradient temperature difference described in Embodiment 1; the system comprises:

[0121] A configuration module, used for setting a first basic boundary condition and a second basic boundary condition;

[0122] A construction module, used to construct a first wind tunnel concrete wall model in a finite element analysis software based on a first basic boundary condition, and to construct a second wind tunnel concrete wall model in a structural design software based on a second basic boundary condition;

[0123] A solution module is used to mesh the first wind tunnel concrete wall model and apply a gradient temperature difference load to each grid to solve the first wall stress; the solution module is also used to apply a conventional load to the second wind tunnel concrete wall model to solve the second wall stress;

[0124] A superposition module, used for superimposing the first cave wall stress and the second cave wall stress to obtain the design control stress;

[0125] The adjustment module is used to carry out concrete cavity wall reinforcement according to the design control stress.

[0126] Embodiment 3: This embodiment provides a computer-readable medium on which a computer program is stored. The computer program is executed by a processor to implement a concrete cave wall design method under a gradient temperature difference as described in Embodiment 1. Specifically, the following steps are performed:

[0127] Step 1: Set the first basic boundary condition and the second basic boundary condition;

[0128] Step 2: constructing a first wind tunnel concrete wall model in finite element analysis software based on the first basic boundary condition, and constructing a second wind tunnel concrete wall model in structural design software based on the second basic boundary condition;

[0129] Step 3: Mesh the concrete wall model of the first wind tunnel, apply gradient temperature difference load to each grid, and solve the first wall stress; apply conventional load to the concrete wall model of the second wind tunnel, and solve the second wall stress;

[0130] Step 4: Superimpose the first cave wall stress and the second cave wall stress to obtain the design control stress;

[0131] Step 5: Reinforce the concrete cavity wall according to the designed controlled stress.

[0132] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for designing a concrete cave wall under the action of a gradient temperature difference, characterized in that: include: Setting a first basic boundary condition and a second basic boundary condition; The setting of the first basic boundary condition specifically includes a method: solving the basic stiffness of the wind tunnel concrete wall based on the M value method; based on the basic stiffness, combining with the equivalent stiffness method, determining the basic short column parameters of the wind tunnel concrete wall: establishing multiple sections of non-laterally constrained cylinders at the bottom of the wind tunnel concrete wall to simulate the basic stiffness, and performing fixed constraints on the bottom of each non-laterally constrained cylinder; solving the parameters of the non-laterally constrained cylinder as the basic short column parameters; The parameter solution method of the cylinder without lateral constraints includes: A single pile model corresponding to the real project is established, and the diameter of the single pile in the single pile model is set to d, and the total length of the single pile does not exceed 6d; the single pile model is divided into n sections of sub-piles with a length of L at equal intervals, n ≥ 10; a bidirectional spring constraint is applied to each section of the sub-pile laterally; the stiffness k of the bidirectional spring constraint is k = m * L * h, where m represents the proportional coefficient of the horizontal resistance coefficient of the foundation soil, and h is the distance from the bidirectional spring to the top of the single pile; the deformation coefficient δ of the single pile model under unit force F is obtained, and the diameter D of the cylinder without lateral constraint is calculated according to the following formula: F / (3EI / H 3 ) = δ; I = π * D 4 / 64; where E is the elastic modulus; I is the section moment of inertia; H is the length of the cylinder without lateral constraints; A first wind tunnel concrete wall model is constructed in the finite element analysis software based on the first basic boundary condition, and a second wind tunnel concrete wall model is constructed in the structural design software based on the second basic boundary condition; a first wind tunnel concrete wall model is constructed based on the BAQUS software, wherein the first wind tunnel concrete wall model includes: a concrete cave body part, a steel structure grid part, a top plate steel beam part, a hanger part and a support part; wherein the constraint condition of the top plate steel beam part is realized by an embedded constraint; the constraint conditions between the support part and the concrete cave body part are all realized by an MPC-beam constraint, and the constraint conditions of the support part include: the outer support is rigidly connected, and the inner support is hinged; The concrete wall model of the first wind tunnel is meshed, and a gradient temperature difference load is applied to each mesh to solve the first wall stress; conventional loads are applied to the concrete wall model of the second wind tunnel to solve the second wall stress; The method of applying a gradient temperature difference load to each grid to solve the first cave wall stress includes: dividing the first wind tunnel concrete cave wall model into multiple structural monomers according to the structural seams: taking the structure between every two structural seams as a structural monomer; screening out typical structural monomers; the typical structural monomers are representative structural monomers screened out from multiple structural monomers of the same type; obtaining the temperature distribution of the wind tunnel concrete cave wall, and applying a gradient temperature difference load to the grids of each typical structural monomer accordingly, calculating the temperature stress of each typical structural monomer based on a static general solver combined with material thermodynamic parameters; merging the temperature stress of all structural monomers based on the temperature stress of each typical structural monomer to obtain the first cave wall stress; The first cave wall stress and the second cave wall stress are superimposed to obtain the design control stress; The concrete cavity wall is reinforced according to the design control stress.

2. The method for designing a concrete cave wall under the action of a gradient temperature difference according to claim 1, characterized in that: The method of constructing a first wind tunnel concrete wall model in finite element analysis software based on the first basic boundary condition includes: The concrete cave part is constructed by the solid unit C3D8R model; the steel structure grid part is constructed by the truss unit T3D2 model; the top plate steel beam part, the hanger part and the support part are all constructed by the beam unit B31 model; The uniaxial constitutive relationship of concrete is constructed based on the mender uniaxial constitutive model; the multiaxial constitutive model of steel is constructed based on the classical plastic metal plasticity model; the uniaxial constitutive relationship of steel is constructed based on the biaxial line model.

3. The method for designing a concrete cave wall under the action of a gradient temperature difference according to claim 2 is characterized in that: The meshing of the first wind tunnel concrete wall model comprises the following method: The entire concrete cavern is evenly divided into N×N grids, N≤H / 4; H represents the thickness of the concrete cavern, wherein the side wall and top plate of the concrete cavern are evenly divided into M×M grids; M∈(1N / 4, 1N / 2); Divide each rod of the steel structure grid into a grid; The top plate steel beam part, the hanger part and the support part are evenly divided into a 2.5N×2.5N grid.

4. The method for designing a concrete cave wall under a gradient temperature difference according to claim 1, characterized in that: The method of carrying out concrete cavity wall reinforcement according to the design stress control includes: Obtain the design control stress, and consider the uneven distribution of the cave wall stress, and reinforce the concrete cave wall in an asymmetrically designed reinforcement form or with additional steel plates: For the asymmetric reinforcement design, if the temperature rise inside the concrete cavity wall exceeds the temperature rise outside the cavity and reaches the preset first temperature threshold, the number of reinforcements outside the cavity is greater than the number of reinforcements inside the cavity; For the reinforcement form of additional steel plates, if the temperature rise inside the concrete cavity wall exceeds the temperature rise outside the cavity and reaches a preset second temperature threshold, a steel plate is added outside the cavity.

5. A concrete cave wall design system under the action of gradient temperature difference, characterized in that: Used to implement a concrete cave wall design method under the action of a gradient temperature difference as described in any one of claims 1 to 4; the system comprises: A configuration module, used for setting a first basic boundary condition and a second basic boundary condition; A construction module, used to construct a first wind tunnel concrete wall model in a finite element analysis software based on a first basic boundary condition, and to construct a second wind tunnel concrete wall model in a structural design software based on a second basic boundary condition; A solution module is used to mesh the first wind tunnel concrete wall model and apply a gradient temperature difference load to each grid to solve the first wall stress; the solution module is also used to apply a conventional load to the second wind tunnel concrete wall model to solve the second wall stress; A superposition module, used for superimposing the first cave wall stress and the second cave wall stress to obtain the design control stress; The adjustment module is used to carry out concrete cavity wall reinforcement according to the design control stress.

6. A computer readable medium having a computer program stored thereon, characterized in that: The computer program is executed by a processor to implement a method for designing a concrete cave wall under a gradient temperature difference as described in any one of claims 1 to 4.

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