A numerical simulation method for the spacing of transverse channels and parking positions in an extremely long interval based on the stratification of fire smoke

Abstract

The present invention provides a numerical simulation method for the spacing of transverse channels and the parking position in an extra-long interval based on the stratification of fire smoke, including: determining a fire dynamics calculation model, determining the geometric parameters of the extra-long interval and the operating train, determining boundary conditions, determining the numerical simulation grid size, establishing a numerical model for the study of the spacing of transverse channels - parking position in the extra-long interval, solving and determining the numerical model for the analysis of the spacing of transverse channels - parking position in the extra-long interval, obtaining the temperature in the area near the tunnel vault, the temperature in the area near the ground, the average temperature of the tunnel cross-section, the calculated smoke layer height, the standard empirical formula for smoke layer stratification and the stratification critical value, and determining the spacing of transverse channels set in the extra-long interval and the relative parking position of the train. It can realize the calculation and analysis of the smoke layer height, the stratification critical value and the standard empirical formula for stratification, improve the numerical simulation ability of the evacuation and rescue technology for urban rail transit, ensure the safety of personnel evacuation and rescue, and promote the process of project refinement.

Description

Technical Field

[0001] The present invention relates to the field of numerical simulation of urban rail transit, and particularly relates to a numerical simulation method and system for the spacing of transverse channels - parking positions in an extra-long interval based on fire smoke stratification. Background Art

[0002] In 2018, the Standard Quota Institute of the Ministry of Housing and Urban-Rural Development issued the "Guidelines for the Planning and Design of Suburban Express Rail Transit", which pointed out that suburban express rail transit, abbreviated as suburban express line, is characterized by large station spacing, full closure, with a maximum operating speed of 100 km / h to 160 km / h and a target of 1 hour for the whole journey operation control time, connecting the main towns, hub points or new town development zones along the line.

[0003] The process of urban modernization in China is accelerating continuously, and more and more cities are starting to develop urban underground transportation. All cities and departments attach great importance to the development of urban rail transit. Urban rail transit has many advantages, such as: high speed, strong passenger transportation capacity, pollution-free, punctual operation time, safety, convenience, etc. The passenger transportation capacity, speed and safety of rail transit far exceed other means of transportation. The planning and construction of rail transit are a necessary condition for the process of urban modernization.

[0004] The distance of urban rail transit intervals is getting longer and longer, from the ordinary urban center interval with a length of 1 km to the extra-long interval with a length greater than 20 km connecting airports and satellite cities. Fire is one of the most serious accidents in the extra-long interval tunnels of urban rail transit. Due to the uniqueness of the vehicles, structures, traffic conditions, etc. in the extra-long interval tunnels, the suddenness of extra-long interval fire accidents is strong, the difficulty of discharging fire smoke is great, and the difficulty of evacuating people during a fire is great. Design, construction and operation units will pay sufficient attention in their respective responsible links.

[0005] In terms of disaster prevention and rescue, it is necessary to consider the scenario where the train stays in the interval. The vehicle is preferably parked at the station for evacuation and rescue, but many irresistible factors still pose a risk that the train stays in the extra-long interval. Therefore, evacuation and rescue facilities such as rescue stations and transverse channels can be set in the extra-long interval. The fire smoke spreads to both ends of the interval, and there will be a section of the distance where the fire smoke stratification is stable, and then sedimentation occurs. If the set spacing is too large, it will cause the transverse channel position to be in the smoke sedimentation area, and if the spacing is too small, the project economy cannot be guaranteed. Similarly, the relative position where the train stops at the rescue station or transverse channel should also be within the stable section of fire smoke stratification. Therefore, determining the spacing of transverse channels set in the extra-long interval and the relative position where the train stops at the rescue station or transverse channel is particularly important for disaster prevention and rescue in the extra-long interval.

[0006] At present, the spacing of transverse channels is mainly determined by referring to the experience of similar projects, and there is no scientific and safe method for actual engineering calculations. For ordinary sections, it is possible to directly consider the evacuation and rescue after a train accident at a station. However, for extremely long sections, the condition of the train stopping within the section should be considered. At present, the consideration of the parking position in this scenario is not perfect. To solve the above engineering and technical problems, the present invention provides a numerical simulation analysis method for the spacing of transverse channels and parking positions in extremely long sections based on the stratification of fire smoke, ensuring the safety of personnel evacuation and rescue and realizing the refinement of engineering design parameters. Summary of the Invention

[0007] In view of the deficiencies of the above-mentioned prior art, the present invention provides a numerical simulation method and system for the spacing of transverse channels and parking positions in extremely long sections based on the stratification of fire smoke, realizing the refinement of engineering design parameters, ensuring the safety of personnel evacuation and rescue, and having very important guiding significance for similar rail transit extremely long section projects.

[0008] According to the first aspect of the present invention, there is provided a numerical simulation method for the spacing of transverse channels and parking positions in extremely long sections based on the stratification of fire smoke, including:

[0009] Step 10: Determine the fire dynamics calculation model, including the turbulence model and the combustion model.

[0010] Step 20: Determine the geometric parameters of the extremely long section and the operating train, where the geometric parameters include: the geometric dimensions of the tunnel cross-section, the geometric dimensions of the train cross-section, and the train length.

[0011] Step 30: Determine the boundary conditions, where the boundary conditions include: the inlet and outlet pressures, the wind speed, the fire source power, the wall material, the ambient temperature, and the ambient pressure.

[0012] Step 40: Determine the numerical simulation grid size.

[0013] Step 50: According to the solution methods of the finite difference method and the Runge-Kutta method, establish a numerical model for the study of the spacing of transverse channels and parking positions in extremely long sections.

[0014] Step 60: Solve and determine the numerical model for the analysis of the spacing of transverse channels and parking positions in extremely long sections to obtain the temperature in the ceiling area of the section tunnel, the problems in the area near the ground, and the average temperature of the tunnel cross-section.

[0015] Step 70: Calculate the smoke layer height, the stratification critical value, and the standard empirical formula for stratification.

[0016] Step 80: Determine the spacing of transverse channels to be set in the extremely long section and the relative parking position of the train.

[0017] Furthermore, in the method provided by the present invention, step 10 further includes:

[0018] The turbulence calculation model uses large eddy simulation to directly solve large-scale turbulent motion, and uses the Smagorinsky subgrid model for small-scale turbulent motion, which is expressed as:

[0019]

[0020]

[0021]

[0022] Among them, μ LES is the viscosity coefficient of large eddy simulation; k LES is the thermal conductivity of large eddy simulation; ρ is the density; D is the diffusion coefficient; Δ is the grid characteristic length; c s is an empirical constant, ranging from 0.2 to 0.21; is the deformation rate tensor; Pr t is the turbulent Prandtl number, which is taken as 0.5; Sc t is the turbulent Schmidt number, which is 0.7; “-” is the average value, is a vector.

[0023] Furthermore, in the method provided by the present invention, step 10 further comprises:

[0024] The combustion model adopts the mixed fraction combustion model, which is expressed as:

[0025]

[0026]

[0027] Among them, Y F is the mass fraction of fuel; is the mass fraction at the fuel source; is the mass fraction of oxygen; is the mass fraction of oxygen in the initial environment; s is the introduction coefficient; is the calculation coefficient of oxygen; v F is the calculation coefficient of fuel reaction; is the relative molecular weight of oxygen; M F is the relative molecular weight of the fuel; O is oxidant; F is fuel; P is products; Z is the process variable; “→” indicates the conversion relationship.

[0028] Furthermore, in the method provided by the present invention, step 40 further includes:

[0029] The grid size is calculated using the fire source characteristic diameter method, expressed as:

[0030]

[0031] Among them, D · is the characteristic diameter of the heat source; ρ ∞ is the air density; c p is the specific heat capacity of air; T a is the ambient air temperature; g is the acceleration due to gravity; Q is the heat source power.

[0032] Furthermore, in the method provided by the present invention, step 70 further includes: The smoke layer height is calculated by the integral ratio method, expressed as:

[0033] r(H i ) = min(r) = min(r u + r l )

[0034]

[0035] Among them: r is the integral ratio; r u is the upper layer integral ratio; r l is the lower layer integral ratio; H i is the smoke layer height, m; T(y) is the vertical temperature distribution function, and the Sigmoidal function can be used to approximate and fit the temperature distribution curve; H is the tunnel height; y is the height in the vertical direction.

[0036] Furthermore, in the method provided by the present invention, step 70 further includes:

[0037] The stratification critical value is determined by comparing the stratification standard and the stratification factor. The better the smoke stratification, the closer it is to 1, expressed as:

[0038] Stratification standard:

[0039] Stratification factor:

[0040] Among them: T c is the temperature near the tunnel vault area; T f is the temperature near the tunnel floor area; T avg is the average temperature of the tunnel cross-section; ΔT cf is the temperature difference between the tunnel vault temperature and the tunnel floor temperature; ΔT h is the temperature difference between the tunnel vault temperature and the tunnel ambient air temperature; ΔT avg is the temperature difference between the average temperature of the tunnel cross-section and the tunnel ambient air temperature.

[0041] Furthermore, in the method provided by the present invention, step 70 further includes:

[0042] The empirical formula of the stratification standard can be obtained by using a relevant exponential equation, expressed as:

[0043]

[0044] where a and b are correlation coefficients; x e is the reference position.

[0045] According to a second aspect of the present invention, there is provided a computer device, characterized by comprising:

[0046] a memory for storing instructions; and a processor for calling the instructions stored in the memory to execute the method of the first aspect.

[0047] According to a third aspect of the present invention, there is provided a computer-readable storage medium, characterized by storing instructions, which when executed by a processor, execute the method of the first aspect.

[0048] Compared with the prior art, the above technical solution conceived by the present invention has at least the following beneficial effects:

[0049] (1) It is possible to realize the calculation and analysis of the smoke layer height, stratification critical value and empirical formula of the stratification standard, improve the numerical simulation ability of the evacuation and rescue technology for urban rail transit, ensure the safety of personnel evacuation and rescue, and promote the process of engineering refinement. It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present invention.

[0050] (2) It realizes the analysis of the judgment standard for the smoke layer stratification in a super-long interval fire, determines the critical value of the smoke layer stratification in a super-long interval fire, promotes the design of the cross-passage parameters for urban rail transit, and optimizes the design scheme for the super-long interval of urban rail transit.

[0051] (3) It realizes the precise control and dynamic regulation of the traffic safety in the super-long interval of urban rail transit, and improves the rationality of the position selection of the train when it stops in the super-long interval.

[0052] (4) Using the numerical simulation method to analyze the cross-passage spacing - parking position in the super-long interval, calculate and analyze the smoke layer height, stratification critical value and empirical formula of the stratification standard, and ensure the operation safety in the super-long interval on the premise of ensuring the rationality of the project cost.

[0053] (5) It realizes the refined research and rapid design of the traffic safety in the super-long interval of urban rail transit, and provides technical support for the research and design of the operation ventilation of this type of project in the super-long interval of urban rail transit. Description of the Drawings

[0054] The accompanying drawings here are incorporated into and constitute a part of this specification, showing embodiments consistent with the present invention and, together with the specification, used to explain the principles of the present invention.

[0055] Figure 1 is the flowchart of the numerical simulation method for the cross - passage spacing - parking position in an extra - long section.

[0056] Figure 2 is the relationship diagram between the fire smoke stratification standard and the dimensionless distance.

[0057] Figure 3 is the relationship diagram between the value of a and the dimensionless wind speed v*.

[0058] Figure 4 is the determination diagram of the critical value of fire smoke temperature stratification.

[0059] Figure 5 is the critical stratification length diagram of the fire smoke layer. Detailed implementation manners

[0060] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0061] A numerical simulation method for the cross - passage spacing - parking position in an extra - long section based on fire smoke stratification according to the present invention specifically adopts the following steps:

[0062] (1) Determine the fire dynamics calculation model, including the turbulence model and the combustion model.

[0063] As a preferred embodiment, the large - eddy simulation is selected as the turbulence calculation model, directly solving the large - scale turbulence motion and adopting the Smagorinsky sub - grid model for the small - scale turbulence motion. It is expressed as:

[0064]

[0065]

[0066]

[0067] Among them, μ LES is the viscosity coefficient of the large - eddy simulation; k LES is the thermal conductivity coefficient of the large - eddy simulation; ρ is the density; D is the diffusion coefficient; Δ is the grid characteristic length; c s is an empirical constant, generally 0.2 - 0.21; is the deformation rate tensor; Pr t is the turbulent Prandtl number, generally taken as 0.5; Sc t is the turbulent Schmidt number, generally taken as 0.7; "-" is the average value, is a vector.

[0068] As a preferred embodiment, the combustion model is selected as the mixture fraction combustion model, expressed as:

[0069]

[0070]

[0071] Among them, Y F is the mass fraction of the fuel; is the mass fraction at the fuel source; is the mass fraction of oxygen; is the mass fraction of oxygen in the initial environment; s is the introduction coefficient; is the calculation coefficient of oxygen; v F is the calculation coefficient of the fuel reaction; is the relative molecular weight of oxygen; M F is the relative molecular weight of the fuel; O is oxidant; F is fuel; P is products; Z is the process variable; "→" represents the conversion relationship.

[0072] (2) Determine the geometry parameters of the ultra-long section and the operating train, and the geometry parameters include: the geometric size of the tunnel section, the geometric size of the train section, and the train length.

[0073] (3) Determine the boundary conditions, and the boundary conditions include: the inlet and outlet pressure, wind speed, fire source power, wall material, environmental temperature, and environmental pressure.

[0074] (4) Determine the numerical simulation grid size.

[0075] As a preferred embodiment, the grid size can adopt the fire source characteristic diameter calculation method, expressed as:

[0076]

[0077] Among them, D · is the fire source characteristic diameter, m; ρ ∞ is the air density, kg / m 3 ; c p is the specific heat capacity of air, kJ / (kg-K); T a is the ambient air temperature, K; g is the acceleration of gravity, m / s 2 ; Q is the fire source power, kW.

[0078] (5) According to the solution methods of the finite difference method and the Runge-Kutta method, a numerical model for the study of the cross-passage spacing - parking position in an extra-long interval is established.

[0079] (6) Solve and determine the numerical model for the analysis of the cross-passage spacing - parking position in an extra-long interval, and obtain the temperature in the ceiling area of the interval tunnel, the problem in the area near the ground, and the average temperature of the tunnel cross-section.

[0080] (7) Calculate and analyze the smoke layer height, stratification critical value, and stratification standard empirical formula.

[0081] As a preferred embodiment, the smoke layer height can be calculated using the integral ratio method, expressed as:

[0082] r(H i ) = min(r) = min(r u +r l )

[0083]

[0084] Where: r is the integral ratio; r u is the upper layer; r l is the lower layer; H i is the smoke layer height, m; T(y) is the vertical temperature distribution function, and the temperature distribution curve can be approximated and fitted using the Sigmoidal function; H is the tunnel height, and y is the height in the vertical direction.

[0085] As a preferred embodiment, the stratification critical value can be determined by comparing the stratification standard and the stratification factor. The better the smoke stratification, the closer it is to 1, expressed as:

[0086] Stratification standard:

[0087] Stratification factor:

[0088] Where: T c is the temperature close to the tunnel vault area, K; T f is the temperature close to the tunnel ground area, K; T avg is the average temperature of the tunnel cross-section, K; ΔT cf is the temperature difference between the tunnel vault temperature and the tunnel ground temperature, K; ΔT h is the temperature difference between the tunnel vault temperature and the tunnel ambient air temperature, K; ΔT avg is the temperature difference between the average temperature of the tunnel cross-section and the tunnel ambient air temperature, K.

[0089] As a preferred embodiment, the stratification standard empirical formula can be obtained using a relevant exponential equation, expressed as:

[0090]

[0091] Wherein, H is the tunnel height, in m; a and b are correlation coefficients; x e is the reference position, in m.

[0092] (8) Determine the spacing of the transverse channels in the extra-long section and the relative position of the train stop.

[0093] The present invention also includes a system for implementing the above method, namely a numerical simulation system for the spacing - stop position of transverse channels in an extra-long section based on the stratification of fire smoke, including:

[0094] (1) A fire dynamics calculation module for performing: determining the turbulence model and the combustion model. The large eddy simulation is selected as the turbulence calculation model to directly solve the large-scale turbulent motion and the Smagorinsky sub-grid model is used for the small-scale turbulent motion. The mixture fraction combustion model is selected as the combustion model.

[0095] (2) A physical model module for performing: determining the geometric parameters of the extra-long section and the running train, and the geometric parameters include: the geometric dimensions of the tunnel cross-section, the geometric dimensions of the train cross-section, and the train length.

[0096] (3) A boundary condition input module for performing: determining the boundary conditions, and the boundary conditions include: the inlet and outlet pressures, the wind speed, the fire source power, the wall material, the ambient temperature, and the ambient pressure.

[0097] (4) A grid setting module for performing: determining the numerical simulation grid size. The grid size can be calculated by the fire source characteristic diameter method.

[0098] (5) A numerical simulation model establishment module for performing: establishing a numerical model for the study of the spacing - stop position of transverse channels in the extra-long section according to the solution methods of the finite difference method and the Runge - Kutta method.

[0099] (6) A data analysis module for performing: solving and determining the numerical model for the analysis of the spacing - stop position of transverse channels in the extra-long section, obtaining the temperature in the ceiling area of the interval tunnel, the problems in the area near the ground, and the average temperature of the tunnel cross-section, and analyzing to obtain the smoke layer height, the stratification critical value, and the standard empirical formula for stratification. The smoke layer height can be calculated by the integral ratio method. The stratification critical value can be determined by comparing and judging through the stratification standard and the stratification factor. The standard empirical formula for stratification can be obtained by using a relevant exponential equation.

[0100] (8) An output result module for performing: determining the spacing of the transverse channels in the extra-long section and the relative position of the train stop.

[0101] Specifically, corresponding to each step, there are specific embodiments as follows:

[0102] (1) Determine the fire dynamics calculation model

[0103] For the turbulence calculation model, large eddy simulation is selected to directly solve the large-scale turbulent motion and the Smagorinsky sub-grid model is used for the small-scale turbulent motion. It is expressed as:

[0104]

[0105]

[0106]

[0107] Among them, μ LES is the viscosity coefficient of large eddy simulation; k LES is the thermal conductivity coefficient of large eddy simulation; ρ is the density; D is the diffusion coefficient; Δ is the grid characteristic length; c s is an empirical constant, generally 0.2 - 0.21; is the deformation rate tensor; Pr t is the turbulent Prandtl number, generally taken as 0.5; sc t is the turbulent Schmidt number, generally taken as 0.7; "-" is the average value, is a vector.

[0108] For the combustion model, the mixture fraction combustion model is selected, which is expressed as:

[0109]

[0110]

[0111] Among them, Y F is the mass fraction of the fuel; is the mass fraction at the fuel source; is the mass fraction of oxygen; is the mass fraction of oxygen in the initial environment; s is the introduction coefficient; is the calculation coefficient of oxygen; v F is the calculation coefficient of fuel reaction; is the relative molecular weight of oxygen; M F is the relative molecular weight of the fuel; O is oxidant; F is fuel; P is products; Z is the process variable; "→" represents the conversion relationship.

[0112] (2) Determine the geometric parameters of the extra-long section and the operating trains

[0113] The model is 1200 m long and 6.5 m high. The vehicle type is urban area type D train, with 8 sets of formations. The dimensions of each carriage are: 22.8 m long, 3.3 m wide, and 3.8 m high.

[0114] (3) Determine the numerical simulation boundary conditions

[0115] The wall material of the interval tunnel is "concrete", and its conductivity, density, and specific heat are 1.8 W / (m·K), 2280 kg / m³, and 1.04 kJ / (kg·K) respectively. The train material is "steel", and its conductivity, density, and specific heat are 45.8 W / (m•K), 7850 kg / m³, and 0.46 kJ / (kg·K) respectively. The ambient temperature is 293 K, and the ambient pressure is 101.32 kPa.

[0116] The fire source powers are 10.5 MW, 7.5 MW, and 5 MW; there are 8 longitudinal wind speeds, which are 0.2 m / s, 0.4 m / s, 0.6 m / s, 0.8 m / s, 1.0 m / s, 1.2 m / s, 1.4 m / s, and 1.6 m / s respectively.

[0117] (4) Determine the numerical simulation grid size

[0118] In this study, the maximum fire source power is 10.5 MW. Through the fire source characteristic diameter calculation method, D* = 2.43 is obtained, so the grid size ranges from 0.15 m to 0.61 m. Considering the computer performance and the timeliness of the simulation, the grid size is selected as 0.25 m x 0.25 m × 0.25 m.

[0119] (5) Analysis of the numerical simulation results of the cross-passage spacing - parking position

[0120] The evacuation platform is located on one side of the tunnel, and people need to walk on the evacuation platform after leaving the carriage. Taking the study of the evacuation platform position in the extra-long interval as an example, the relationship between the fire smoke stratification standard and the dimensionless distance is as Figure 2 , the evacuation platform includes two areas, the train area and the non-train area. Generally speaking, for the same fire source power and different longitudinal wind speed conditions, as the distance from the fire source increases, the value of the smoke stratification standard gradually decreases. The mathematical laws of the two dimensionless terms in the train area are not obvious because the train area belongs to a double-narrow long space and is relatively close to the fire source, and the smoke thermal buoyancy is strong under different conditions. There is a "wake" area between the train area and the non-train area, which affects the spread of smoke. In the non-train area, for different fire heat release rate conditions, the change law of the smoke stratification standard in the track area downstream of the fire source is similar. As the dimensionless distance from the fire source increases, the smoke stratification standard gradually decreases, and there is an exponential decay relationship between the two dimensionless terms.

[0121] Since the value of b does not vary significantly, in this study, the value of b will be averaged. The relationship between a and the dimensionless wind speed is shown in Figure 3 From the figure, it can be seen that the correlation between the two variables basically shows a linear relationship fitting with a correlation coefficient R2 of 0.9, indicating a good data fitting effect.

[0122] Figure 4 It is a diagram for determining the critical value of smoke stratification in a tunnel fire. When the smoke stratification is better, the value of ΔT cf is closer to the value of ΔT h , and the ratio between the two is close to 1. When the smoke stratification state gradually deteriorates, a significant temperature rise also appears in the lower space of the tunnel cross-section, which leads to a decrease in the value of ΔT cf , thus resulting in a decrease in the value of ΔT cf / ΔT h . In the evacuation platform area, the value of ΔT cf / ΔT h has an inflection point corresponding to a value of ΔT cf / ΔT avg of 2.4. When ΔT cf / ΔT avg ≥2.4, the smoke stratification state is good. However, in the train area, when the heat release rate of the fire source ranges from 5 MW to 10.5 MW, the values of the smoke stratification standard are all greater than 2.6.

[0123] The following table is the data fitting results and correlation coefficient table of the smoke stratification standard and the dimensionless distance in a fire:

[0124]

[0125] After Figure 2 , Figure 3 and the above table analysis, the empirical formula for the smoke movement stratification standard in the evacuation platform of an extra-long section is as follows.

[0126]

[0127] (6) Determine the spacing of the transverse channels in the extra-long section and the relative position of the train stop.

[0128] The critical stratification length of the fire smoke layer is as shown in Figure 5 . The critical stratification length of the fire smoke decreases with the increase of the longitudinal wind speed. The higher the heat release rate of the fire source, the more obvious the decreasing trend of the smoke critical stratification length. Because the greater the heat release rate of the fire source, the more smoke is generated downstream of the fire and the stronger the turbulence. In the current research scope, from the perspective of stable smoke stratification, referring to the 0.2 m / s working condition and the 10.5 MW working condition, the stable smoke stratification length is about ±90 m from the fire source; for the 7.5 MW working condition, the stable smoke stratification length is about ±135 m from the fire source; for the 5 MW working condition, the stable smoke stratification length is about ±160 m from the fire source.

[0129] The evacuation passage can be set in the area where the smoke stratification is clear. When the train stops in the interval tunnel, the train should ensure that the evacuation position is within the critical stratification range of the smoke layer. The spacing of the extra-long interval cross-passage and the relative position of the train stop are determined comprehensively by the empirical formula and the critical value.

[0130] It should be understood that the present invention is not limited to the exact structure already described and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A numerical simulation method for the spacing of transverse channels and parking positions in an extremely long interval based on the stratification of fire smoke, characterized in that, Including: Step 10: Determine the fire dynamics calculation model, including the turbulence model and the combustion model; Step 20: Determine the geometric parameters of the extra-long section and the running train. The geometric parameters include: the geometric dimensions of the tunnel cross-section, the geometric dimensions of the train cross-section, and the train length; Step 30: Determine the boundary conditions. The boundary conditions include: the inlet and outlet pressure, wind speed, fire source power, wall material, ambient temperature, and ambient pressure; Step 40: Determine the numerical simulation grid size; Step 50: Establish a numerical model for studying the cross-passage spacing - parking position in the extra-long section according to the solution methods of the finite difference method and the Runge-Kutta method; Step 60: Solve and determine the numerical model for analyzing the cross-passage spacing - parking position in the extra-long section to obtain the temperature in the ceiling area of the tunnel section, the problems in the area near the ground, and the average temperature of the tunnel cross-section; Step 70: Calculate the smoke layer height, the stratification critical value, and the standard empirical formula for stratification; Step 80: Determine the cross-passage setting spacing in the extra-long section and the relative parking position of the train.

2. The method according to claim 1, wherein Step 10 further includes: The large eddy simulation is selected for the turbulence model, and the large-scale turbulent motion is directly solved, while the Smagorinsky sub-grid model is used for the small-scale turbulent motion, which is expressed as: ； ； ； wherein, is the viscosity coefficient of large eddy simulation; is the thermal conductivity of large eddy simulation; is the density; is the diffusion coefficient; is the grid characteristic length; is an empirical constant, and its value range is 0.2 to 0.21; is the deformation rate tensor; is the turbulent Prandtl number, taking 0.5; is the turbulent Schmidt number, taking 0.7; "-" represents the average value, and "⇀" represents the vector.

3. The method according to claim 2, wherein Step 10 further includes: The mixture fraction combustion model is selected for the combustion model, which is expressed as: ； ； Among them, is the mass fraction of the fuel; is the mass fraction at the fuel source; is the mass fraction of oxygen; is the mass fraction of oxygen in the initial environment; is the introduction coefficient; is the calculation coefficient of oxygen; is the calculation coefficient of fuel reaction; is the relative molecular weight of oxygen; is the relative molecular weight of the fuel, O is oxidant, F is fuel, P is products, Z is the process variable, and "→" represents the conversion relationship.

4. The method according to claim 1, wherein Step 40 further includes: The grid size is calculated using the fire source characteristic diameter and is expressed as: ; Among them, is the characteristic diameter of the heat source; is the air density; is the specific heat capacity of air; is the ambient air temperature; is the acceleration due to gravity; is the heat source power.

5. The method according to claim 1, wherein Step 70 further includes: The smoke layer height is calculated using the integral ratio method, which is expressed as: ； ； Where: r is the integration ratio; is the upper-layer integration ratio; is the lower-layer integration ratio; is the height of the smoke layer, m; is the vertical temperature distribution function, and the Sigmoidal function can be used to approximate and fit the temperature distribution curve; is the tunnel height, and y is the height in the vertical direction.

6. The method according to claim 5, characterized in that, Step 70 further includes: The stratification critical value is determined by judging and comparing the stratification standard and the stratification factor. The better the flue gas stratification, the closer it is to 1, expressed as: ； ； Wherein: is the temperature in the area close to the tunnel vault; is the temperature in the area close to the tunnel floor; is the average temperature of the tunnel cross-section; is the temperature difference between the tunnel vault temperature and the tunnel floor temperature; is the temperature difference between the tunnel vault temperature and the tunnel ambient air temperature; is the temperature difference between the average temperature of the tunnel cross-section and the tunnel ambient air temperature; Step 70 further includes: The empirical formula for the stratification standard can be obtained using a relevant exponential equation, expressed as: ; where a and b are correlation coefficients; is the reference position.

7. A computer device, characterized in that, Including: A memory for storing instructions; A processor for calling the instructions stored in the memory to execute the method according to any one of claims 1-6.

8. A computer-readable storage medium, characterized in that, Instructions are stored, and when the instructions are executed by the processor, the method according to any one of claims 1-6 is executed.

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