A design method for supporting columns in ultra-high tunnels with low turbulence and high wind pressure

Abstract

The present invention belongs to the field of architectural design technology, and discloses a design method for ultra-high tunnel support columns that can withstand ultra-high wind pressure and low turbulence. The present invention compares the steel consumption of a column model with a column model and a column-free model in a large-span section to determine the layout position of the tunnel support columns; selects several tunnel support column structures in combination with the structural span; comprehensively analyzes various tunnel support column structures by setting the ultimate bearing capacity, and selects the tunnel support column structure with the lowest steel consumption; obtains the drag coefficient of each tunnel support column structure, and selects the tunnel support column structure with the least impact on the internal flow field of the wind tunnel; combines the relevant characteristics of the tunnel support column structure with the lowest steel consumption and the tunnel support column structure with the least impact on the internal flow field of the wind tunnel to obtain the optimal tunnel support column. The present invention can add structural support columns in the tunnel body to reduce the roof span and optimize its economy while ensuring that the quality of the wind tunnel airflow is not affected, and provide reference and reference for the design of tunnel columns.

Description

Technical Field

[0001] The present invention relates to the field of architectural design, and in particular to a design method for an ultra-high in-tunnel support column that can withstand ultra-high wind pressure and low turbulence. Background Art

[0002] A wind tunnel is a test facility that uses artificially created and controlled airflow to simulate the distribution and movement of air around an object. Wind tunnel design is a comprehensive and groundbreaking project that requires exploring, demonstrating, and researching the feasibility, rationality, and economic efficiency of various technical approaches, solutions, and indicators.

[0003] A review of the current state of research at home and abroad reveals a paucity of case studies specifically targeting large-scale wind tunnels, leaving little valuable experience to draw upon. Due to the extremely complex design requirements for large wind tunnels, along with their exceptional length, spaciousness, large spans, and unusual shapes, they require significant amounts of steel. This is especially true at corners, where the roof trusses require larger spans to ensure structural stability and prevent impacts on the wind tunnel. Furthermore, in structural design, larger spans require more steel, and the economic cost of achieving these spans is higher. However, existing technologies have yet to address the economic benefits and cost reduction challenges associated with large-scale wind tunnels. Summary of the Invention

[0004] The present invention aims to address the deficiencies of the prior art and to provide a design method for support columns in ultra-high tunnels that can withstand extremely high wind pressures and low turbulence. By adopting this solution, structural support columns can be added to the tunnel body to reduce the span of the wind tunnel roof, optimize its economic efficiency, and provide a solution for similar projects, while ensuring that the quality of the wind tunnel airflow is not affected.

[0005] The present invention is achieved through the following technical solutions:

[0006] A design method for supporting columns in ultra-high tunnels with low turbulence and high wind pressure, comprising the following steps:

[0007] For the long-span sections of the wind tunnel, the steel usage of the column-with and column-free models was compared based on the maximum stress ratio limit to determine the layout of the supporting columns within the tunnel.

[0008] At the layout location, through reasonable allocation with the roof grid and combined with the structural span, several types of in-hole support column structures are selected. The in-hole support column structure is a hollow or mesh structure.

[0009] By setting the ultimate bearing capacity, a comprehensive analysis of the cross-sectional configuration, structural performance, and steel consumption of various in-hole support column structures is conducted, and the in-hole support column structure with the lowest steel consumption is selected;

[0010] Analytical calculation models for various in-tunnel support column structures were established, and the flow field values ​​of various in-tunnel support column structures were simulated and analyzed to obtain the drag coefficient of each in-tunnel support column structure. By comparing the velocity distribution and noise distribution of various in-tunnel support column structures on the cross section, the in-tunnel support column structure with the least impact on the flow field inside the wind tunnel was selected;

[0011] The optimal in-tunnel support column is obtained by combining the relevant characteristics of the in-tunnel support column structure with the lowest steel consumption and the in-tunnel support column structure with the least impact on the internal flow field of the wind tunnel.

[0012] In a further solution, several types of in-hole supporting column structures were selected, including circular tube columns, lattice trough columns, lattice spindle columns, lattice box columns and hollow thick plate columns;

[0013] The limbs of the lattice-type trough-type column have grooves on one or both sides of the cross-section; the limbs of the lattice-type spindle-shaped column have spindle-shaped cross-sections; the limbs of the lattice-type box-type column have box-shaped cross-sections; and the limbs of the hollow thick plate column are steel plates.

[0014] A further solution is to comprehensively analyze the cross-sectional configuration, structural performance and steel consumption of the lattice trough column, and set the cross-sectional configuration as two-limb, three-limb and four-limb lattice trough column respectively, and connect the adjacent limbs in the lattice trough column by a number of tie bars; then, the minimum steel consumption is explored for the two-limb, three-limb and four-limb lattice trough columns respectively, and the in-hole supporting column structure with the lowest steel consumption among the three is obtained.

[0015] A further approach is to explore the minimum steel usage for two-limb and three-limb lattice channel columns according to the varying limb height, limb thickness and limb spacing.

[0016] For the four-limb lattice trough column, according to the stability strength calculation formula, it is first assumed that the stability coefficients of the four-limb lattice trough column in the X and Y directions are the same; then the design bearing capacity is determined, and the spacing between two adjacent branches of the four-limb lattice trough column in the X and Y directions under different stability coefficients and different branch thicknesses is reversed, thereby obtaining the cross-sectional parameters with the lowest steel consumption of the four-limb lattice trough column, thereby obtaining the minimum steel consumption.

[0017] A further solution is to comprehensively analyze the cross-sectional configuration, structural performance and steel consumption of the lattice-type spindle column, and respectively set the cross-sectional configuration to several structures with different limbs or size ratio changes;

[0018] Subsequently, the buckling modes of several structures were simulated to obtain the buckling eigenvalues. Based on the buckling eigenvalue analysis results, an initial defect of 1 / 250 column height was imposed on several structures in both axial directions, and a double nonlinear analysis was performed on the columns considering the plasticity of the material. Based on the analysis results, the minimum biaxial buckling bearing capacity of the lattice spindle column was taken, and through comparison, the in-hole support column structure with the lowest steel consumption among several structures was obtained.

[0019] A further solution is to comprehensively analyze the cross-sectional configuration, structural performance and steel consumption of the hollow thick plate column, and set the cross-sectional configuration to a double-limb hollow thick plate column, with adjacent steel plates connected by diaphragms;

[0020] The thickness of the two limbs is kept constant, and the thickness of the diaphragm is increased from small to large. The buckling mode is simulated and parameter analysis is performed to obtain the change data of the weak axis eigenvalue and the strong axis instability mode order.

[0021] Based on the instability mode, an initial defect of 1 / 250 column height was imposed, and a double nonlinear analysis was performed. According to the ultimate bearing capacity, the diaphragm thickness with the lowest steel consumption was obtained.

[0022] A further solution is to comprehensively analyze the cross-sectional configuration, structural performance, and steel consumption of the lattice box column and set the cross-sectional configuration to be a double-legged lattice box column; the lattice box column is provided with stiffening ribs, and adjacent lattice box columns are connected by a number of support rods and diagonal braces;

[0023] Different parameters were set and combined for the double-limb plate thickness, stiffener plate thickness, support rod size, and number of diagonal supports. Buckling modes were simulated and parameter analysis was performed to obtain the weak axis eigenvalue and strong axis instability mode order change data.

[0024] Based on the instability mode, an initial defect of 1 / 250 column height was applied to conduct a double nonlinear analysis. The steel usage under various combinations was obtained based on the ultimate bearing capacity. The obtained steel usage was compared with the steel usage of the remaining supporting column structures in the hole to determine the steel usage of the lattice box column.

[0025] Further solutions include selecting the supporting column structure with the least impact on the flow field inside the wind tunnel:

[0026] Establish analytical calculation models of various supporting column structures in the cave through Fluent;

[0027] Determine the size of the outer flow domain and use the Mesh module to divide the polyhedron mesh, refine the mesh of the middle area of ​​the outer flow field and divide it into a certain number of grid nodes;

[0028] Using the k-epsilon turbulence model, setting the boundary conditions of the inlet velocity and noise model, and performing steady-state calculations from the inlet initialization, we obtained the drag coefficient monitoring results of various in-hole support column structures, and converged after several iterative calculations.

[0029] By comparing the velocity distribution and noise distribution of various in-tunnel support column structures on the cross section, the in-tunnel support column structure with the least impact on the internal flow field of the wind tunnel is selected.

[0030] A further approach to combining the characteristics of the tunnel support column structure with the lowest steel consumption and the least impact on the flow field inside the wind tunnel includes:

[0031] The double-limbed lattice box column was selected as the supporting column structure with the lowest steel consumption, and the lattice fusiform column was selected as the supporting column structure with the least impact on the flow field inside the wind tunnel.

[0032] The lattice box column is rectified by using the two-end diversion characteristics of the lattice shuttle column. The two ends of the lattice box column are rounded, with a round head on the windward side and a pointed tail on the leeward side. By combining these two, the optimal in-hole supporting column is obtained.

[0033] A further solution, after obtaining the rectified lattice box column, is to obtain the specific dimensions of the supporting column in the hole through finite element analysis, including the following steps:

[0034] When the other structural and performance characteristics are determined, several different single-limb heights, single-limb wall thicknesses, stiffener thicknesses, and double-limb spacings are selected for finite element analysis.

[0035] The analysis model uses a shell element model and takes into account initial defects. The initial defects are simulated by introducing the deformation of the first-order elastic buckling mode of the column in the hole at 1 / 300.

[0036] By applying a vertical downward displacement to the top of the column and performing DNZ1 analysis, the first-order elastic buckling mode, stress distribution contour map under the ultimate bearing capacity state, final failure state and load-displacement curve of each supporting column in the hole are obtained;

[0037] According to the finite element calculation structure distribution, the variation curves of various parameters and ultimate bearing capacity are drawn. According to the variation law of the influence of various parameters on bearing capacity, the optimal specific dimensions of the lattice box column are obtained while meeting the ultimate bearing capacity design target and good economy.

[0038] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0039] 1. The present invention provides a design method for supporting columns in an ultra-high tunnel that can withstand extremely high wind pressure and low turbulence. By adopting this solution, structural supporting columns can be added inside the tunnel to reduce the span of the wind tunnel roof and optimize its economic efficiency, while ensuring that the quality of the wind tunnel airflow is not affected.

[0040] 2. This invention provides a design method for supporting columns in tunnels withstanding extremely high wind pressures and low turbulence. It proposes various feasible cross-sectional forms for these columns and conducts computational analysis, aerodynamic performance, and streamlined design studies. Through comparison, a rational column structure was identified that effectively supports force while minimizing the impact on the wind tunnel flow field. Detailed research was also conducted on the parameters of various column components and the joint configurations at the top and bottom of the columns, offering solutions for similar projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] 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 examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings:

[0042] Figure 1 A schematic flow chart of a design method for a high-pressure, low-turbulence, ultra-high tunnel support column provided by the present invention;

[0043] Figure 2 A diagram showing the calculation model of the circular tubular column provided by the present invention;

[0044] Figure 3 A diagram showing the calculation model of the lattice-type trough column provided by the present invention;

[0045] Figure 4 A diagram showing the calculation model of the lattice-type spindle column provided by the present invention;

[0046] Figure 5 A diagram showing the calculation model of the lattice box column provided by the present invention;

[0047] Figure 6 A diagram showing the calculation model of the hollow thick plate column provided by the present invention;

[0048] Figure 7 A front view of a double-limb lattice-type trough column provided by the present invention;

[0049] Figure 8 A top view of the double-limb lattice-type trough column provided by the present invention;

[0050] Figure 9 A front view of a three-limb lattice-type trough column provided by the present invention;

[0051] Figure 10 A top view of the three-limb lattice-type trough column provided by the present invention;

[0052] Figure 11 A front view of a four-limb lattice-type trough column provided by the present invention;

[0053] Figure 12 A top view of the four-limb lattice-type trough column provided by the present invention;

[0054] Figure 13 A front view of a lattice-type spindle-shaped column provided by the present invention;

[0055] Figure 14 A top view of the lattice-type spindle column provided by the present invention;

[0056] Figure 15 A front view of a hollow slab column provided by the present invention;

[0057] Figure 16 A top view of the hollow slab column provided by the present invention;

[0058] Figure 17 A top view of the double-limb lattice box column provided by the present invention;

[0059] Figure 18 A front view of a double-limb lattice box column provided by the present invention;

[0060] Figure 19 A three-dimensional diagram of the rectified lattice box column provided by the present invention;

[0061] In the figure, 10 is the calculation model of circular tube column; 20 is the calculation model of lattice trough column; 30 is the calculation model of lattice spindle column; 40 is the calculation model of lattice box column; 50 is the calculation model of hollow thick plate column; 60 is the double-limb lattice trough column, 61 is the first limb, 62 is the first circular tube tie bar; 70 is the three-limb lattice trough column, 71 is the second limb, 72 is the second circular tube tie bar, 73 is the third limb; 80 is the four-limb lattice trough column, 81 is the fourth limb, 82 is the third circular tube tie bar; 90 is the lattice spindle column, 91 is the fifth limb, 92 is the fourth circular tube tie bar; 100 is the hollow thick plate column, 101 is the sixth limb, 102 is the cross-diaphragm; 110 is the double-limb lattice box column, 111 is the seventh limb, 112 is the support rod; 120 is the lattice box column after rectification and transformation. DETAILED DESCRIPTION

[0062] 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 examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0063] The design principle of the tunnel support columns is: the tunnel support columns are arranged at the intersection of the horizontal lower chord grid and the vertical lower chord grid of the upper grid of the wind tunnel test flow channel, and the spacing between adjacent tunnel support columns is equal; in order to facilitate the arrangement of the column top grid supports, and at the same time, they are arranged as evenly as possible so that the spans of adjacent grids are as uniform as possible, thereby achieving better economic benefits.

[0064] Based on the above arrangement principle of tunnel support columns, the embodiment of the present invention provides a design method for tunnel support columns that can withstand ultra-high wind pressure and low turbulence. Figure 1 This is a flow chart of a design method for supporting columns in ultra-high tunnels with low turbulence and high wind pressure. Figure 1 A design method for a high-pressure, low-turbulence, ultra-high tunnel support column specifically includes the following steps:

[0065] S1. For the large-span sections in the wind tunnel, the steel usage of the column model and the column-free model is compared based on the maximum stress ratio limit to determine the layout of the supporting columns in the tunnel.

[0066] The amount of steel used reflects economic efficiency; the lowest steel usage results in the best economic efficiency. To achieve even better economic efficiency, while ensuring that the quality of the wind tunnel airflow is not compromised, the addition of structural support columns within the tunnel to reduce the roof span is considered. The wind tunnel's largest span sections, namely the corner sections, were selected for design. Modeling was performed for these large-span sections, with and without support columns within the tunnel. These selected large-span sections are defined below as "Section 1" and "Section 2," respectively.

[0067] Specifically, calculations and analyses were performed under the same maximum stress ratio limit, and the steel consumption was calculated. The results are shown in Table 1. The results show that the column-free model for Section 1 uses 65% more steel than the model with columns, while the column-free model for Section 2 uses 54% more steel than the model with columns. Therefore, the structural solution of adding supporting columns within the tunnel was ultimately adopted for Sections 1 and 2.

[0068] Table 1: Comparison of steel structure usage for models with columns and without columns

[0069] .

[0070] Based on the aforementioned column-in-hole design, a comprehensive calculation model of the upper grid and lower concrete structure was established for the corner locations, using finite element analysis software. Concrete columns, grid members, roof members, and side panel members were calculated and analyzed using beam element models, while rib walls and slabs were calculated using plate elements. The bottoms of all rib walls and columns were set as fixed boundaries, and the column tops were connected to the grid supports with rigid connections on the outside and hinged connections on the inside.

[0071] To achieve better economic benefits, supporting columns were installed in the tunnel sections with larger spans (Sections 1 and 2). A comparison of the structural schemes with and without columns showed that the installation of columns significantly reduced the amount of structural steel used in Sections 1 and 2.

[0072] The parameters of the in-tunnel supporting column foundation model of any structure are matched. According to the in-tunnel column layout principle, the matched in-tunnel supporting column foundation model is set in the long-span section model. The total steel consumption of the long-span section model and the in-tunnel supporting column foundation model is calculated under the condition of the same maximum stress ratio limit. The optimal in-tunnel column layout scheme is obtained through different layout schemes.

[0073] S2. At the layout position, through reasonable allocation with the roof grid division and combined with the structural span, several types of in-hole support column structures are selected. The in-hole support column structure is a hollow or mesh structure.

[0074] The embodiment of the present invention compares various configurations of supporting columns, including circular tube columns, lattice trough columns, lattice spindle columns, lattice box columns and hollow thick plate columns, and establishes the basic model of each column, respectively. Figure 2-6 shown.

[0075] The limbs of the lattice-type trough-type column have grooves on one or both sides of the cross-section; the limbs of the lattice-type spindle-shaped column have spindle-shaped cross-sections; the limbs of the lattice-type box-type column have box-shaped cross-sections; and the limbs of the hollow thick plate column are steel plates.

[0076] S3, by setting the ultimate bearing capacity, comprehensively analyze the cross-sectional configuration, structural performance and steel consumption of each column in the tunnel, and select the tunnel supporting column structure with the lowest steel consumption.

[0077] Calculate the supporting columns in the hole for each configuration provided in S2:

[0078] For circular tubular columns, the steel consumption and ultimate bearing capacity of each column were directly calculated for different outer diameters and wall thicknesses. The cylindrical foundation model with the lowest steel consumption that met the ultimate bearing capacity requirements was retained. Specifically, the cross-section of the solid circular steel tubular column was selected to be 1400mm (diameter) x 40mm (wall thickness), with a radius of gyration of ix = iy = 481mm and a slenderness ratio of λ = 66.52, meeting the slenderness ratio limits specified in the Code for Seismic Design of Buildings. Taking Sections 1 and 2 as an example, the calculated design value for the column's axial pressure was 22844.7 kN, the column stability factor ψ = 0.6915, the design bearing capacity was 30290 kN, and the design stress ratio was 0.754. This meets the reasonable stress level requirements for a critical vertical component, provides a sufficient safety factor, and takes economic considerations into account. The advantages of this column shape are reliable performance and mature design methods. However, its disadvantages are its large diameter and large windward surface, which significantly impacts airflow.

[0079] For lattice-type trough columns, the steel consumption and ultimate bearing capacity of lattice-type trough column foundation models with different variables and configurations are directly calculated, and the lattice-type trough column foundation model with the lowest steel consumption that meets the ultimate bearing capacity requirements is retained.

[0080] In the specific analysis, during the calculation process, the design bearing capacity N = 31256KN is the target (the design bearing capacity is determined), and according to the requirements, the flange width is b = 200mm (the flange width is determined). For the two-legged lattice trough column and the three-legged lattice trough column, see Figures 7 to 10 , based on the variable branch height, branch thickness, and branch spacing, the optimal two-leg lattice trough column and the optimal three-leg lattice trough column with the minimum steel consumption under the ultimate bearing capacity requirements are calculated. After calculation, the two-leg lattice trough column: the branch height is 1600mm, and the steel consumption is the lowest. When the branch height is greater than 1600mm, the lattice column calculation is controlled by the web height-to-thickness ratio, which causes the branch thickness to no longer decrease, and the steel consumption will begin to increase. The three-leg lattice trough column: the branch height is 1400mm, and the steel consumption is the lowest. When the branch height is greater than 1400mm, the lattice column calculation is controlled by the web height-to-thickness ratio, which causes the branch thickness to begin to increase, and the steel consumption will begin to increase.

[0081] For four-limb lattice channel columns, see Figure 11-12Because four-leg lattice columns involve numerous variables, including C (spacing of the limbs in the X-direction), h (spacing of the limbs in the Y-direction), t (limb thickness), and h1 (limb height), an exhaustive approach would be impractical and unnecessary. This is because the stability strength calculation formula for four-leg lattice columns is N = φAf, where N is the bearing capacity, φ is the stability factor, A is the limb area, and f is the design compressive strength of the material. If the bearing capacity is determined, the strength is primarily governed by the stability factor φ, while the stability factor is primarily governed by C and h. The economic efficiency is best when the stability factors determined in both directions are equal, indicating that the strength in both directions is fully utilized. According to the stability strength calculation formula, the stability coefficients of the four-legged lattice column in the X and Y directions are assumed to be the same. The design bearing capacity N = 31256 kN is then determined. The spacing between adjacent limbs in the X and Y directions is then calculated for different stability coefficients φ (0.6 to 0.9) and limb thicknesses (15 mm to 40 mm). This leads to the minimum cross-sectional parameters of the four-legged lattice column and, consequently, the optimal four-legged lattice column with the minimum steel requirement. Calculations show that steel requirement decreases with increasing stability coefficient. However, when limb thickness t < 15 mm or stability coefficient φ > 0.86, the local and limb stability of the lattice column no longer meet requirements. This indicates that the appropriate selection of the rectangular tube wall thickness and stability coefficient is crucial for achieving both stability and economic efficiency in the lattice column.

[0082] Since the calculation of four-limb lattice columns with different wall thicknesses is based on the design bearing capacity of 31256KN, under a certain stability coefficient φ=0.86, the limb area is determined (A=123200mm 2 ), that is, the limb thickness t will only have a relatively significant impact on the limb height. In addition, compared with double limbs and triple limbs, four limbs use the least steel and are the most economical.

[0083] In general, for lattice trough columns of different configurations, the optimal two-limb lattice trough columns, the optimal three-limb lattice trough columns and the optimal four-limb lattice trough columns are respectively set to be connected by a number of tie bars; then the lattice trough column with the minimum steel consumption among the optimal two-limb lattice trough columns, the optimal three-limb lattice trough columns and the optimal four-limb lattice trough columns is retained.

[0084] For lattice spindle columns, see Figure 13-14The fusiform column offers similar economic advantages to lattice columns, and its limbs have a fusiform cross-section, significantly reducing the impact of a single limb on the airflow within the cavity. However, fusiform columns are more difficult to construct, and the limbs require a large number of tie bars to connect them, which can still affect the airflow quality within the circuit to some extent. The calculation method involves obtaining simulated buckling modes, buckling eigenvalues, and strong-axis instability mode order data for different variables. Using the buckling eigenvalues ​​as a benchmark, an initial imperfection (in this example, an initial imperfection of 1 / 250 the column height is applied, taking material plasticity into account) is applied to the lattice fusiform column foundation model in both directions. A dual nonlinear analysis is performed to determine the minimum biaxial buckling capacity. Lattice fusiform column foundation models that meet the ultimate bearing capacity requirements are selected, and the lattice fusiform column foundation model with the lowest steel consumption is retained. The analysis shows that the advantages of the fusiform column are its fusiform limbs, tie bar diameter of approximately 200 mm, and its reduced impact on airflow compared to conventional lattice columns. The disadvantage is that there are no ready-made theories and cases, and more in-depth theoretical and experimental research is needed to ensure that its performance meets the design requirements, and it is difficult to implement.

[0085] For hollow slab columns, see Figure 15-16 , obtain the simulated buckling modes, buckling eigenvalues ​​and strong-axis instability mode order change data for different variables (limb steel plate thickness, limb spacing, steel partition thickness and spacing). Based on the instability mode, an initial defect (an initial defect of 1 / 250 column height is applied) is applied to the lattice thick plate column foundation model for double nonlinear analysis. While meeting the ultimate bearing capacity requirements, the hollow thick plate column foundation model with the lowest steel consumption is retained.

[0086] Specifically, this embodiment directly adopts the solution of steel plate composite columns, which can reduce the difficulty of manufacturing and implementing each component, and is beneficial to ensuring performance and controlling quality. The thickness of the two limbs is set to be 180mm, and the thickness of the diaphragm starts from 20mm and reaches 180mm. The parameter analysis is carried out with 20mm as the module. When the diaphragm is 160mm, the fifth order of the buckling mode of the steel plate composite column is strong axis buckling. The eigenvalue results of the steel plate composite column show that with the thickening of the diaphragm, the weak axis eigenvalue increases significantly, the strong axis remains basically unchanged, and the order of the strong axis instability mode gradually advances. Taking the above-mentioned instability mode as the benchmark, an initial defect of 1 / 250 column height is applied, and a double nonlinear analysis is carried out. The results show that when the diaphragm is greater than or equal to 60mm thick, this solution is feasible. When the diaphragm is 80mm thick, it is more economical and can meet the design requirements. When the diaphragm is thickened, the column's weak axis bearing capacity increases significantly, while the strong axis bearing capacity remains essentially unchanged. When the diaphragm is less than 160 mm, the buckling capacity of the strong and weak axes differs significantly. Future optimization efforts will focus on aligning the buckling capacity of the two axes as closely as possible to improve cost efficiency. The current solution is more expensive than the fusiform composite column and has a lower material utilization rate, leaving significant room for improvement. Further analysis will be conducted.

[0087] With a target ultimate bearing capacity of 40,000-50,000 kN, steel plate composite columns, regardless of whether bracing is provided, require significantly more steel than lattice columns. To ensure global buckling occurs before local buckling, the plate thickness cannot be effectively reduced. The inclusion of supporting columns does not effectively optimize the economic efficiency of steel plate composite columns.

[0088] For lattice box columns, see Figure 17-18 The calculation and analysis method is the same as that for the hollow thick plate column. Different parameters are set for the branch cross-sectional size, branch spacing, number and thickness of stiffeners, support rod size, and support spacing variables. The simulated buckling mode, buckling eigenvalue, and strong-axis instability mode order change data of different variables are obtained. Based on the instability mode, an initial defect (an initial defect of 1 / 250 column height is applied in this embodiment) is applied to the lattice box column foundation model for dual nonlinear analysis. The lattice box column foundation model with the lowest steel consumption is retained while meeting the ultimate bearing capacity requirements.

[0089] Specifically, the cross-sectional size of a single limb is 2000*200 mm 2 The center spacing is 2000mm, and support rods with an outer diameter of Φ150mm and a wall thickness of 8mm are set. Its characteristic buckling bearing capacity and ultimate bearing capacity are shown in Table 2.

[0090] Table 2: Calculation results of double-leg lattice box columns

[0091] .

[0092] The analysis results show that the lattice box column uses less steel and the stability of the single limb and plate is easier to ensure.

[0093] In summary, a comprehensive analysis of the cross-sectional configurations, structural performance, and steel consumption of various supporting columns shows that, under the condition that the ultimate bearing capacity of the columns is basically the same, the steel consumption of solid circular columns, lattice-type trough columns, and lattice-type box columns is the lowest.

[0094] S4. Analytical and computational models for various in-tunnel support column structures are established, and the flow field values ​​of various in-tunnel support column structures are simulated and analyzed to obtain the drag coefficient of each in-tunnel support column structure. By comparing the velocity distribution and noise distribution of various in-tunnel support column structures on the cross section, the in-tunnel support column structure with the least impact on the flow field inside the wind tunnel is selected.

[0095] Various structural forms of in-hole support columns, including circular tubular columns, lattice trough columns, lattice spindle columns, and lattice box columns, were established, and computational fluid dynamics software was used to perform numerical simulation analysis of the flow fields of these support column forms.

[0096] Specifically, based on Figure 2-Figure 6For the analytical calculation model shown, the entire outer flow domain is 8m wide and 2m high. The model is 5m away from the inlet and 10m away from the outlet. The Mesh module is used to create a polyhedral mesh, and the mesh in the central region of the outer flow field is refined to approximately 1 million nodes. The k-epsilon turbulence model is used for both boundary conditions and solution. The inlet velocity is a fixed value, and the broadband noise model is used. Initialization is performed from the inlet, and steady-state calculations are performed. First, the drag coefficient monitoring results are obtained. Convergence is achieved after approximately 100 iterative calculations, as shown in Table 3.

[0097] Table 3: Drag coefficients of various columns

[0098] .

[0099] It can be seen from the above table that the lattice spindle column has the smallest drag coefficient; the lattice box column has fillers added at the front and back, which means that the two ends of the lattice box column are rounded, with a round head on the windward side and a pointed tail on the leeward side.

[0100] Because the support columns are located within the cavity, their configuration affects the quality of the airflow field. Numerical simulations of the flow field show that the spindle-shaped column minimizes the drag coefficient. Lattice-shaped spindle columns optimize the aerodynamic profile, effectively reducing wake width and pulsation intensity, and significantly reducing turbulence. Therefore, the lattice-shaped spindle column is a more suitable option.

[0101] S5, the relevant characteristics of the tunnel support column structure with the lowest steel consumption and the tunnel support column structure with the least impact on the internal flow field of the wind tunnel are combined to obtain the optimal tunnel support column.

[0102] Considering that the economic index of the lattice-type shuttle column scheme is too high, it is considered to rectify the lattice-type box column and make it smooth at both ends, with a round head on the windward side and a pointed tail on the leeward side. The drag coefficient of this configuration is also small, which can achieve the goal of both excellent airflow quality and economy. The role of the round head on the windward side and the pointed tail on the leeward side is not considered in the structural design. Figure 19 shown.

[0103] After obtaining the rectified lattice box columns, finite element analysis was required to determine the specific dimensions of the supporting columns within the tunnel. Taking the columns within the first tunnel of Section 1 as an example, the design parameters were as follows: column height 45.6m, design ultimate bearing capacity target 81,000kN, support configuration at both ends of the column: hinged at the top and fixed at the bottom, and a default angle of 45° between the diagonal tie bars and the axis of the two side members. Based on the aerodynamic performance and streamlined design of in-hole columns, a single-leg width and tie-rib width of 200 mm were adopted. Finite element analysis was performed with various single-leg heights (1800 mm, 1900 mm, and 2000 mm), single-leg wall thicknesses (35 mm, 40 mm, and 45 mm), stiffener thicknesses (40 mm, 45 mm, and 50 mm), and double-leg spacings (1400 mm, 1500 mm, and 1600 mm). The analysis model used shell elements, and initial imperfections were considered. These initial imperfections were simulated by introducing a 1 / 300 deformation at the first-order elastic buckling mode of the in-hole column. A vertical downward displacement was applied to the column top, ultimately generating a load-displacement curve for each column. Using the DNZ1 analysis process and results as an example, the first-order elastic buckling mode, stress distribution contours at the ultimate bearing capacity state, final failure state, and load-displacement curve were obtained for each in-hole supporting column.

[0104] Finally, the calculation results for the in-hole column under various parameters were obtained. Based on the finite element calculation results, curves were plotted showing the relationship between each parameter and the ultimate bearing capacity. The curves show that the ultimate bearing capacity of a two-leg lattice column increases with increasing single-leg wall thickness, and the relationship is essentially linear. The ultimate bearing capacity of a two-leg lattice column increases with increasing single-leg height, and the increasing trend is more pronounced. The stiffening rib thickness and the spacing between the two legs have little effect on the ultimate bearing capacity of the two-leg lattice column. The influence of each parameter on the bearing capacity indicates that the single-leg wall thickness and height should be prioritized during design. The stiffening rib thickness and spacing between the two legs have a minimal impact on the bearing capacity, and smaller values ​​should be selected for design. Furthermore, considering the impact on structural economy, the single-leg wall thickness should be minimized due to the greater steel consumption caused by the long column length. Under the premise of meeting the ultimate bearing capacity design goals and achieving good economic efficiency, the optimal double-leg lattice column solution at this stage was ultimately determined: a single-leg wall thickness of 35 mm, a single-leg height of 1900 mm, a stiffening rib plate thickness of 45 mm, and a spacing of 1500 mm between the legs and the cross-ties. This resulted in the final design results for the in-hole support column.

[0105] This proposal not only reduces the roof span and optimizes economic efficiency by adding structural support columns within the wind tunnel while ensuring uncompromising airflow quality, but also proposes a variety of feasible column cross-sections, conducts computational analysis of the columns, and investigates their aerodynamic performance and streamlined shapes. Through comparison, a suitable column structure was identified that effectively supports loads while minimizing impact on the wind tunnel flow field. Detailed research was also conducted on the parameters of various column components and the joint configurations at the top and bottom of the columns, providing valuable insights and references for the design of the columns for this project.

[0106] 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 design method for supporting columns in ultra-high tunnels that can withstand extremely high wind pressure and low turbulence, characterized in that: The following steps are involved: For the long-span sections of the wind tunnel, the steel usage of the column-with and column-free models was compared based on the maximum stress ratio limit to determine the layout of the supporting columns within the tunnel. At the layout location, through reasonable allocation with the roof grid and combined with the structural span, several types of in-hole support column structures are selected. The in-hole support column structure is a hollow or mesh structure. By setting the ultimate bearing capacity, a comprehensive analysis of the cross-sectional configuration, structural performance, and steel consumption of various in-hole support column structures is conducted, and the in-hole support column structure with the lowest steel consumption is selected; Analytical calculation models for various in-tunnel support column structures were established, and the flow field values ​​of various in-tunnel support column structures were simulated and analyzed to obtain the drag coefficient of each in-tunnel support column structure. By comparing the velocity distribution and noise distribution of various in-tunnel support column structures on the cross section, the in-tunnel support column structure with the least impact on the flow field inside the wind tunnel was selected; The optimal in-tunnel support column is obtained by combining the relevant characteristics of the in-tunnel support column structure with the lowest steel consumption and the in-tunnel support column structure with the least impact on the internal flow field of the wind tunnel.

2. The design method of a support column for an ultra-high tunnel with low turbulence and high wind pressure according to claim 1 is characterized in that: Several types of in-hole supporting column structures were selected, including circular tube columns, lattice trough columns, lattice spindle columns, lattice box columns and hollow slab columns. The limbs of the lattice-type trough-type column have grooves on one or both sides of the cross-section; the limbs of the lattice-type spindle-shaped column have spindle-shaped cross-sections; the limbs of the lattice-type box-type column have box-shaped cross-sections; and the limbs of the hollow thick plate column are steel plates.

3. The design method of a support column for an ultra-high tunnel with low turbulence and high wind pressure according to claim 2 is characterized in that: When comprehensively analyzing the cross-sectional configuration, structural performance and steel consumption of a single column of a lattice-type trough column, the cross-sectional configurations were set as two-limb, three-limb and four-limb lattice-type trough columns, and adjacent limbs in the lattice-type trough columns were connected by a number of tie bars; then the minimum steel consumption was explored for the two-limb, three-limb and four-limb lattice-type trough columns, and the in-hole supporting column structure with the lowest steel consumption among the three was obtained.

4. The design method of a support column in an ultra-high tunnel capable of withstanding ultra-high wind pressure and low turbulence according to claim 3 is characterized in that: For two-limb and three-limb lattice channel columns, the minimum steel consumption is investigated according to the varying limb height, limb thickness, and limb spacing. For the four-limb lattice trough column, according to the stability strength calculation formula, it is first assumed that the stability coefficients of the four-limb lattice trough column in the X and Y directions are the same; then the design bearing capacity is determined, and the spacing between two adjacent branches of the four-limb lattice trough column in the X and Y directions under different stability coefficients and different branch thicknesses is reversed, thereby obtaining the cross-sectional parameters with the lowest steel consumption of the four-limb lattice trough column, thereby obtaining the minimum steel consumption.

5. The design method of a support column in an ultra-high tunnel capable of withstanding ultra-high wind pressure and low turbulence according to claim 2 is characterized in that: When comprehensively analyzing the cross-sectional configuration, structural performance, and steel consumption of a single column of a lattice-type spindle column, the cross-sectional configuration was set to several structures with different limbs or size ratios. Then, the buckling modes of several structures were simulated to obtain the buckling eigenvalues; Based on the results of the buckling eigenvalue analysis, an initial defect of 1 / 250 of the column height was imposed on several structures in both axial directions. Taking into account the plasticity of the material, a double nonlinear analysis of the columns was performed. Based on the analysis results, the minimum biaxial buckling bearing capacity of the lattice spindle column was taken, and through comparison, the in-hole support column structure with the lowest steel consumption among the several structures was obtained.

6. The design method of a support column in an ultra-high tunnel capable of withstanding ultra-high wind pressure and low turbulence according to claim 2 is characterized in that: When comprehensively analyzing the cross-sectional configuration, structural performance, and steel consumption of the hollow thick plate column, the cross-sectional configuration was assumed to be a double-limbed hollow thick plate column, with adjacent steel plates connected by diaphragms. The thickness of the two limbs is kept constant, and the thickness of the diaphragm is increased from small to large. The buckling mode is simulated and parameter analysis is performed to obtain the change data of the weak axis eigenvalue and the strong axis instability mode order. Based on the instability mode, an initial defect of 1 / 250 column height was imposed, and a double nonlinear analysis was performed. According to the ultimate bearing capacity, the diaphragm thickness with the lowest steel consumption was obtained.

7. The design method of a support column in an ultra-high tunnel capable of withstanding ultra-high wind pressure and low turbulence according to claim 2 is characterized in that: When comprehensively analyzing the cross-sectional configuration, structural performance, and steel consumption of a single column, a double-legged lattice box column was used as the cross-sectional configuration. Stiffening ribs were provided inside the lattice box column, and adjacent lattice box columns were connected by a number of support rods and diagonal braces. Different parameters were set and combined for the double-limb plate thickness, stiffener plate thickness, support rod size, and number of diagonal supports. Buckling modes were simulated and parameter analysis was performed to obtain the weak axis eigenvalue and strong axis instability mode order change data. Based on the instability mode, an initial defect of 1 / 250 column height was applied to conduct a double nonlinear analysis. The steel usage under various combinations was obtained based on the ultimate bearing capacity. The obtained steel usage was compared with the steel usage of the remaining supporting column structures in the hole to determine the steel usage of the lattice box column.

8. The design method of a support column in an ultra-high tunnel capable of withstanding ultra-high wind pressure and low turbulence according to claim 1 is characterized in that: Methods for selecting the in-tunnel support column structure that has the least impact on the flow field inside the wind tunnel include: Establish analytical calculation models of various supporting column structures in the cave through Fluent; Determine the size of the outer flow domain and use the Mesh module to divide the polyhedron mesh, refine the mesh of the middle area of ​​the outer flow field and divide it into a certain number of grid nodes; Using the k-epsilon turbulence model, setting the boundary conditions of the inlet velocity and noise model, and performing steady-state calculations from the inlet initialization, we obtained the drag coefficient monitoring results of various in-hole support column structures, and converged after several iterative calculations. By comparing the velocity distribution and noise distribution of various in-tunnel support column structures on the cross section, the in-tunnel support column structure with the least impact on the internal flow field of the wind tunnel is selected.

9. The design method of a support column for an ultra-high tunnel capable of withstanding ultra-high wind pressure and low turbulence according to claim 1 is characterized in that: The method of combining the related characteristics of the tunnel support column structure with the minimum steel consumption and the minimum impact on the flow field inside the wind tunnel includes: The double-limbed lattice box column was selected as the supporting column structure with the lowest steel consumption, and the lattice fusiform column was selected as the supporting column structure with the least impact on the flow field inside the wind tunnel. The lattice box column is rectified by using the two-end diversion characteristics of the lattice shuttle column. The two ends of the lattice box column are rounded, with a round head on the windward side and a pointed tail on the leeward side. By combining these two, the optimal in-hole supporting column is obtained.

10. The design method of a support column in an ultra-high tunnel capable of withstanding ultra-high wind pressure and low turbulence according to claim 9, characterized in that: After obtaining the rectified lattice box column, the specific dimensions of the supporting column in the hole are obtained through finite element analysis, including the following steps: When the other structural and performance characteristics are determined, several different single-limb heights, single-limb wall thicknesses, stiffener thicknesses, and double-limb spacings are selected for finite element analysis. The analysis model uses a shell element model and takes into account initial defects. The initial defects are simulated by introducing the deformation of the first-order elastic buckling mode of the column in the hole at 1 / 300. By applying a vertical downward displacement to the top of the column and performing DNZ1 analysis, the first-order elastic buckling mode, stress distribution contour map under the ultimate bearing capacity state, final failure state and load-displacement curve of each supporting column in the hole are obtained; According to the finite element calculation structure distribution, the variation curves of various parameters and ultimate bearing capacity are drawn. According to the variation law of the influence of various parameters on bearing capacity, the optimal specific dimensions of the lattice box column are obtained while meeting the ultimate bearing capacity design target and minimizing the steel consumption.

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