Calculation method for simulating pre-applied axial force of steel support by changing temperature

Abstract

The invention relates to a calculation method for simulating a pre-applied axial force of a steel support by utilizing temperature change, and discloses a numerical simulation method for applying the pre-applied axial force to an inner support through a temperature field based on ABAQUS, which comprises the following steps: firstly, establishing an inner support model, finishing pretreatment setting in the ABAQUS, determining the temperature corresponding to the pre-applied axial force through a formula, and calculating the pre-applied axial force according to the temperature corresponding to the pre-applied axial force; a corresponding temperature field is applied to the model to determine a formula application condition, a numerical simulation method for applying the pre-applied axial force to an inner support system of the'adjustable end + steel support 'is determined on the basis of the formula application condition, and errors of different steel support spans and pre-applied axial force values to the pre-applied axial force in numerical simulation are analyzed.

Description

Technical Field

[0001] The invention relates to a calculation method for simulating the preloaded axial force of a steel support by changing temperature Background Art

[0002] The steel tube concrete internal support is mainly composed of a fixed length steel support and several short-connected sections and a length-adjustable flexible end. It has been widely used in open excavation pits due to its irreplaceable advantages of convenient assembly and disassembly, light weight, recyclable and reusable to save costs, and deformation of the maintenance structure caused by active earth pressure. It is a common measure in foundation pit engineering to apply preloaded axial force by adjusting the length of the flexible joint. Therefore, in order to simulate the actual working conditions, a simulation method for applying preloaded axial force by adjusting the length is required in numerical simulation. Summary of the invention

[0003] The purpose of the present invention is to provide a numerical simulation method for applying pre-axial force to an inner support through a temperature field based on ABAQUS.

[0004] The technical solution adopted to achieve the purpose of the present invention is as follows: a calculation method for simulating the pre-loaded axial force of a steel support by changing the temperature, comprising the following steps: Establish an equivalent segment model of the active end with a length of 1m and a diameter of 0.8m; Complete the pre-processing settings of the active end equivalent segment model through ABAQUS simulation software: 2-1) Define the material properties of the active end equivalent segment model through ABAQUS simulation software; 2-2) Use ABAQUS simulation software to mesh the equivalent segment model of the active end; 2-3) Assemble and position the meshed active end equivalent segment model; 2-4) Create analysis steps and required output variables 2-5) Set the boundary conditions and temperature field of the equivalent segment model of the active end according to the pre-loaded axial force 2-6) Submit the job and extract the axial force value of the equivalent segment model of the active end; 3) Establish a geometric model of an internal support with a diameter of 0.8m, in which the equivalent section of the active end is 1m long and the rest is steel support.

[0005] 4) Complete the pre-processing settings of the internal support model through ABAQUS simulation software: 4-1) Define the material properties of the internal support model using ABAQUS simulation software; 4-2) Mesh the internal support model using ABAQUS simulation software; 4-3) Assemble and position the meshed internal support model; 4-4) Create analysis steps and required output variables 4-5) Set boundary conditions and temperature field according to the pre-loaded axial force of the internal support 4-6) Submit the job and extract the axial force value of the internal support model; 5) Change the overall length of the inner support and the pre-axial force value, submit the changed inner support model for calculation, and obtain the axial force value error of the inner support model and the fitting curve of the pre-axial force error of steel supports with different spans.

[0006] Furthermore, in step 2), the boundary conditions set the displacements of both ends of the equivalent segment of the active end in the axial force direction to be 0.

[0007] Furthermore, in step 2), the temperature field is calculated using the following formula: ; in: F is the preloaded axial force, E is the elastic modulus, A is the cross-sectional area, α Thermal expansion coefficient of steel: 1.25×10 -5 .

[0008] Furthermore, in step 4), the boundary conditions set the displacements at both ends of the inner support in the axial force direction to 0.

[0009] Furthermore, in step 4), temperature fields are applied to the equivalent section of the active end and the steel support respectively.

[0010] Furthermore, in step 5), the error caused by different steel support spans to the pre-loaded axial force is analyzed to obtain the error fitting curve:

[0011] Furthermore, step 5) also includes a step of analyzing the error under different preloaded axial forces.

[0012] The beneficial effects of the present invention are: 1. The present invention determines the temperature corresponding to the pre-axial force through a formula, applies the corresponding temperature field to the model, and determines the applicable conditions of the formula through simulation; 2. The present invention determines a numerical simulation method for applying a pre-axial force to the "flexible end + steel support" internal support system based on the applicable conditions of the formula; 3. The present invention analyzes the error of pre-loaded axial force caused by different steel support spans and pre-loaded axial force values ​​in numerical simulation, and provides a fitting curve of the error caused by different steel support spans to pre-loaded axial force. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The present invention is an overall flow chart of the simulation method.

[0014] Figure 2 This is a diagram of the boundary conditions to which the formula applies.

[0015] Figure 3 Schematic diagram of internal support mesh division.

[0016] Figure 4 The pre-loaded axial force error diagram for steel supports with different spans.

[0017] Figure 5 Simulated error plots for different preload values. DETAILED DESCRIPTION

[0018] The present invention is further described by the following examples, but it should not be understood that the present invention is limited to the following embodiments within the scope of the above subject matter.

[0019] Embodiment 1: This example discloses a simulation method for simulating the pre-loaded axial force of a steel support by changing the temperature, which specifically includes the following steps: 1) Establish a geometric model of the 20m long "flexible end + steel support" internal support, where the equivalent section of the flexible end is 1m long and 0.8m in diameter, and the steel support is 19m long and 0.8m in diameter.

[0020] 2) Complete the model pre-processing settings through ABAQUS simulation software: 2-1) Define the material properties of the model through ABAQUS simulation software; the unit used in this embodiment is m-Pa; the Young's modulus of the equivalent segment of the active end is set to 40000000000, the Poisson's ratio is set to 0.3, the Young's modulus of the steel support is set to 209000000000, and the Poisson's ratio is set to 0.3.

[0021] 2-2) Use ABAQUS simulation software to mesh the model; in ABAQUS software, set the unit type to C3D8R, the global grid to 0.25m, and the precision grid seed to 0.16m. Figure 3 shown.

[0022] 2-3) Assemble and position the meshed model.

[0023] 2-4) Create an analysis step and the required output variables based on the pre-applied axial force; in this embodiment, one analysis step needs to be created.

[0024] 2-5) Set boundary conditions according to the applicable conditions of the formula; in this embodiment, the boundary conditions set the displacement at both ends of the model in the axial force direction to 0.

[0025] 2-6) According to the pre-loaded axial force value, a temperature field is applied to the model in the analysis step created in "2-4)" according to the pre-loaded axial force value of 300kN; the temperature field of the equivalent section of the active end is 1.2℃, and the temperature field of the steel support is 0.228℃ 2-7) Submit the job and extract the model axial force value from the results.

[0026] Embodiment 2: The main steps of this embodiment are the same as those of embodiment 1. Furthermore, in step 1), the lengths of the steel supports are changed to 9m, 14m, 24m, and 29m, respectively, and the axial force values ​​are extracted to obtain the pre-axial force errors of steel supports with different spans, and further obtain the fitting curve, such as Figure 4 shown.

[0027] Embodiment 3: The main steps of this embodiment are the same as those of embodiment 1. Furthermore, the pre-loaded axial force values ​​in step 2) are changed to 100 kN, 200 kN, 400 kN, 500 kN, and 600 kN, respectively, and the corresponding temperature field is applied according to the pre-loaded axial force values. The axial force values ​​are extracted to obtain the simulation errors of different pre-loaded axial force values, such as Figure 5 shown.

Claims

1. A calculation method for simulating the preloaded axial force of a steel support by changing the temperature, characterized in that: The following steps are involved: 1) Establish an equivalent segment model of the active end with a length of 1m and a diameter of 0.8m; 2) Complete the pre-processing settings of the active end equivalent segment model through ABAQUS simulation software: 2-1) Define the material properties of the active end equivalent segment model through ABAQUS simulation software; 2-2) Use ABAQUS simulation software to mesh the equivalent segment model of the active end; 2-3) Assemble and position the meshed active end equivalent segment model; 2-4) Create analysis steps and required output variables 2-5) Set the boundary conditions and temperature field of the equivalent segment model of the active end according to the pre-loaded axial force 2-6) Submit the job and extract the axial force value of the equivalent segment model of the active end; 3) Establish a geometric model of an internal support with a diameter of 0.8m, in which the equivalent section of the active end is 1m long and the rest is steel support; 4) Complete the pre-processing settings of the internal support model through ABAQUS simulation software: 4-1) Define the material properties of the internal support model using ABAQUS simulation software; 4-2) Mesh the internal support model using ABAQUS simulation software; 4-3) Assemble and position the meshed internal support model; 4-4) Create analysis steps and required output variables 4-5) Set boundary conditions and temperature field according to the pre-loaded axial force of the internal support 4-6) Submit the job and extract the axial force value of the internal support model; 5) Change the overall length of the inner support and the pre-axial force value, submit the changed inner support model for calculation, and obtain the axial force value error of the inner support model and the fitting curve of the pre-axial force error of steel supports with different spans.

2. According to claim 1, a calculation method for simulating the preloaded axial force of a steel support by changing the temperature, characterized in that: In step 2), the boundary conditions set the displacement of both ends of the equivalent segment of the active end in the axial force direction to 0.

3. The calculation method for simulating the preloaded axial force of a steel support by changing the temperature according to claim 1 is characterized in that: In step 2), the temperature field is calculated using the following formula: ； in: F is the preloaded axial force, E is the elastic modulus, A is the cross-sectional area, α Thermal expansion coefficient of steel: 1.25×10 -5 .

4. The calculation method for simulating the preloaded axial force of a steel support by changing the temperature according to claim 1 is characterized in that: In step 4), the boundary conditions set the displacements at both ends of the internal support in the axial force direction to 0.

5. The calculation method of simulating the preloaded axial force of a steel support by changing the temperature according to claim 1 is characterized in that: In step 4), the temperature field is applied to the equivalent section of the active end and the steel support respectively.

6. The calculation method for simulating the preloaded axial force of a steel support by changing the temperature according to claim 1 is characterized in that: In step 5), the error caused by different steel support spans to the pre-loaded axial force is analyzed to obtain the error fitting curve:

7. The calculation method for simulating the preloaded axial force of a steel support by changing the temperature according to claim 1 is characterized in that: Step 5) also includes steps for analyzing the errors under different preloaded axial forces.

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