An iterative solution method for heat storage and release of temperature in interval tunnel and surrounding rock soil

Abstract

The present application relates to a kind of interval tunnel air temperature and surrounding rock soil heat storage iterative solution method, comprising: establishing interval tunnel heat balance model, deducing temperature solution formula;Build interval tunnel scale experiment table, obtain tunnel surrounding rock soil initial year by month temperature field, and solve the initial year by month average air temperature of interval tunnel for input, input subway station interval tunnel model established by porous medium soil heat transfer simulation software, obtain the tunnel surrounding rock soil year by month temperature field evolved with year limit, solve the average heat storage and release of surrounding rock soil year by month evolved with year limit, solve the output of interval tunnel year by month average air temperature in iterative process;If the two are not consistent, reiterative solution is carried out until the two are consistent;Finally, the output of the interval tunnel year by month average air temperature and the average heat storage and release of surrounding rock soil year by month evolved with year limit, so that the result obtained is closer to true value.

Description

Technical Field

[0001] This invention relates to the field of subway thermal environment research, and in particular to a method for calculating the air temperature and the heat storage and release of surrounding rock and soil within a subway section. Background Technology

[0002] With the rapid development of China's rail transit, energy consumption control of subway environmental control systems is particularly important. Because subways are buried deep underground, relying solely on station entrances / exits, piston ventilation shafts, and heat exhaust shafts for ventilation, the heat generated by train operation accumulates in the tunnel sections for extended periods, leading to increased air temperature and a deteriorating thermal environment. Therefore, the problem of deteriorating thermal environment within subway tunnels urgently needs to be addressed, and solving this problem first requires understanding the characteristics of the thermal environment within subway tunnels. Currently, there are three main research methods for understanding the thermal environment within subway tunnels:

[0003] One approach involves experiments. Shanghai University of Science and Technology, in its patent application "Experimental Device for Studying the Evolution Law of Soil Temperature and Humidity Field in Metro Tunnel Sections" (Patent Application No.: CN201510167833.1, Publication No.: CN104749347A), disclosed an experimental device for studying the evolution law of soil temperature and humidity field in metro tunnel sections. This device reproduced the temperature and humidity transfer process between air and the surrounding rock and soil of a real metro tunnel section, obtaining the basic laws of the thickness of the heat jacket and temperature distribution of the shield soil within the metro tunnel section. However, in this experiment, the air boundary conditions remained constant for different years, without considering the dynamic changes in tunnel temperature and the heat stored in the surrounding rock and soil over time.

[0004] One approach involves theoretical calculations. The paper "Study on Air Temperature Variation Characteristics under Long-Term Heat Storage and Mechanical Ventilation in Subway Tunnels" establishes a coupled physical and mathematical model of mechanical ventilation and soil heat storage in subway tunnels under an annual cycle, based on the first law of thermodynamics, relevant knowledge of heat transfer, and force-restore theory. The model is then solved to obtain a predictive equation for the air temperature in subway tunnels. However, this theoretical calculation is based on the assumption that the thermal conductivity of the soil is uniform, neglecting the variation of the surrounding rock temperature along the depth direction.

[0005] One approach involves numerical simulation. The paper "Research on Temperature Distribution Characteristics and Monitoring Methods of Subway Tunnels with Platform Screen Door Systems" uses a platform screen door subway as the research object, establishing a typical subway tunnel model and simulating and calculating the thermal environment within the subway tunnel using the SES computer program. However, since the SES software can only perform one-dimensional simulations of subway systems, it simplifies the monthly changing temperature field of the surrounding rock and soil along the depth to the monthly equivalent temperature of the surrounding rock and soil, thus neglecting the temperature variation of the surrounding rock and soil along the depth direction.

[0006] In conclusion, the research methods for the thermal environment inside subway tunnels mentioned above all have certain limitations, and their accuracy still needs to be verified. Summary of the Invention

[0007] Current research methods for studying the thermal environment within subway tunnels suffer from limitations in accuracy and realism. This paper proposes an iterative method combining theoretical calculations and numerical simulations to solve for the evolution of air temperature and heat storage / release in the surrounding rock and soil over time. By integrating theoretical calculations with numerical simulations and iteratively ensuring consistency between the input and output tunnel air temperatures, the obtained results are closer to the actual values.

[0008] The technical solution of this invention is as follows:

[0009] An iterative solution method for calculating the air temperature and heat storage / release of surrounding rock and soil in a tunnel section includes:

[0010] Step 1: Establish a heat balance model for the tunnel section and derive the temperature calculation formula for the annual and monthly average air temperature of the tunnel section:

[0011]

[0012] In equation (4), ρ air —Air density inside the tunnel (kg / m³) 3 ), c p,air —Specific heat capacity of air at constant pressure inside the tunnel (J / (kg·℃)), V —Effective ventilation rate of the piston shaft (m³) 3 ), T out,air —Tunnel exterior air temperature (°C), T in,air —Tunnel interior air temperature (°C), Q train The heat generated by train operation (J), Q soil The heat storage and release of the surrounding rock and soil (J);

[0013] A scaled-down test bench for tunnel sections was built, and the initial annual and monthly temperature field of the surrounding rock and soil of the tunnel was obtained by using the measured monthly tunnel air temperature of a certain region, which remained constant over the years.

[0014] The initial annual and monthly temperature field of the surrounding rock and soil of the tunnel is obtained by solving the temperature solution formula, which is used as the input for the iteration process.

[0015] A subway station tunnel model was established in a porous media soil heat transfer simulation software. The physical properties of the surrounding rock and soil of the tunnel were obtained through scaled-down model experiments and used as the side boundary conditions of the soil.

[0016] Step 2: Input the annual and monthly average air temperature of the tunnel section as the tunnel air temperature boundary condition, input it into the porous media soil heat transfer simulation software, and calculate the annual and monthly temperature field of the tunnel surrounding rock and soil that evolves with the years through software simulation.

[0017] Step 3: Integrate the temperature field of the tunnel surrounding rock and soil over the years to obtain the average heat storage and release of the surrounding rock and soil over the years.

[0018] Step 4: Substitute the average heat stored and released by the surrounding rock and soil over the years into the temperature solution formula to obtain the average temperature of the tunnel over the years and months in the output of the iteration process.

[0019] Step 5: Compare the annual and monthly average temperatures of the tunnels in the input and output during the iteration process. If they are consistent, the annual and monthly average temperatures of the tunnels in the input and output during the iteration process and the annual and monthly average heat storage and release of the surrounding rock and soil are obtained. If they are inconsistent, the annual and monthly average temperatures of the tunnels in the input are substituted into Steps 2 to 5 and iterated again until they are consistent. Then the annual and monthly average temperatures of the tunnels in the input and the annual and monthly average heat storage and release of the surrounding rock and soil are obtained.

[0020] Furthermore, the method for obtaining the initial annual and monthly temperature field of the tunnel surrounding rock in step one is as follows:

[0021] A scaled-down test bench for the tunnel section was constructed. The measured tunnel air temperature of a typical year at a station in the region was used as the boundary condition for the surrounding rock and soil. A scaled-down model experiment was conducted on the air supply to the soil within the scaled-down test bench using an enthalpy difference laboratory. In the experiment, the monthly tunnel air temperature, which remained constant over the years, was used as the air temperature boundary condition for the soil within the scaled-down test bench. The initial annual and monthly temperature fields of the tunnel surrounding rock and soil corresponding to the actual model were obtained for multiple action periods.

[0022] Furthermore, the initial annual and monthly temperature field of the tunnel surrounding rock and soil in step one is solved using the temperature solution formula to obtain the interval initial annual and monthly average air temperature of the tunnel used as input in the iterative process, specifically:

[0023] By integrating the initial annual and monthly temperature field of the surrounding rock and soil along the depth direction, the total heat storage of the surrounding rock and soil in each month can be obtained. By subtracting the total heat storage of the soil in the following month from the total heat storage of the previous month, the average heat storage and release of the surrounding rock and soil in the initial annual and monthly can be obtained.

[0024] The goal is to obtain the average heat density of tunnel sections under a given traffic density in the region during months when trains are operating with and without air conditioning; to obtain the train traffic density in the region during different operating periods; to obtain the effective ventilation rate of the piston ventilation shafts in tunnel sections during the air-conditioned season and the non-air-conditioned season in the region; and to obtain the tunnel air density and the specific heat capacity of air at constant pressure in the region.

[0025] By using the actual data and temperature calculation formula, the annual and monthly average temperature of the input interval tunnel is obtained.

[0026] Furthermore, the specific steps for establishing a subway station tunnel model are as follows:

[0027] Build a 1000*50*1m 3 A model of a subway station tunnel, with an internal diameter of 0.2*1*1000m. 3 The simulated tunnel surrounding rock and soil mass uses an equivalent wind speed of 1.6 m / s inside the tunnel as the wind speed. The physical properties of the tunnel surrounding rock and soil mass are obtained through scaled-down model experiments and used as the side boundary conditions of the soil mass. Part of the simulated tunnel surrounding rock and soil mass structure contains concrete lining.

[0028] Furthermore, the heat balance model for the interval tunnel in step one is as follows:

[0029] Q train +Q wind +Q soil =Q air (1)

[0030] In equation (1), Q train —Heat generated during train operation (J), Q wind —Effective heat transfer of piston air (J), Q soil —Heat storage and release of surrounding rock and soil (J), Q air —Heat stored in the tunnel air (J);

[0031] The derivation of the temperature calculation formula in step one is as follows:

[0032] In the heat balance model of the tunnel section, the heat stored in the tunnel air is neglected, i.e., Q. air =0; by the theorem:

[0033] Q wind =ρ air c p,air V(T out,air -T in,air (2)

[0034] Substituting formula (2) into formula (1), we get:

[0035] Q train +Qsoil +ρ air c p,air V(T out,air -T in,air )=0 (3)

[0036] From formula (3):

[0037]

[0038] In equations (2), (3) and (4): ρ air —Air density inside the tunnel (kg / m³) 3 ), c p,air —Specific heat capacity of air at constant pressure inside the tunnel (J / (kg·℃)), V —Effective ventilation rate of the piston shaft (m³) 3 ), T out,air —Tunnel exterior air temperature (°C), T in,air —Tunnel interior air temperature (°C).

[0039] Furthermore, in step three, the temperature field of the tunnel surrounding rock and soil evolving over time is solved year by year and month by month. The specific operation to obtain the average heat storage and release of the surrounding rock and soil over time is as follows:

[0040] By integrating the temperature field of the tunnel surrounding rock and soil along the depth direction year by year and month by year, the total heat storage of the surrounding rock and soil in each month can be obtained. By subtracting the total heat storage of the soil in the next month from the total heat storage of the previous month, the average heat storage and release of the surrounding rock and soil year by year and month by year can be obtained.

[0041] Furthermore, if the two conditions in step five are consistent, the solution method for obtaining the annual and monthly average air temperature of the tunnel and the annual and monthly average heat storage and release of the surrounding rock and soil as they evolve over time is as follows: When the two conditions are consistent, the output annual and monthly average air temperature of the tunnel as it evolves over time is the actual air temperature of the tunnel under the interaction with the soil. At this time, by integrating the annual and monthly temperature field of the tunnel surrounding rock and soil as it evolves over time along the depth direction, the total heat storage of the surrounding rock and soil in each month can be obtained as it evolves over time. By subtracting the total heat storage of the soil in the next month from the total heat storage of the previous month, the annual and monthly average heat storage and release of the surrounding rock and soil as it evolves over time can be obtained.

[0042] Furthermore, in step five, the method for comparing the annual and monthly average temperatures of the input and output interval tunnels during the comparison iteration process is to subtract the two to obtain the temperature difference.

[0043] Preferably, the method for determining whether the two conditions are consistent in step five is: the accuracy of the maximum temperature difference is 10. -2 Therefore, the two can be considered to be the same.

[0044] Preferably, the porous medium heat transfer simulation software in step two is CHAMP-BES, ANSYS, or COMSOL.

[0045] The beneficial effects of this invention are as follows:

[0046] This invention uses the dynamic tunnel air temperature that evolves over time as a boundary condition, takes into account the change of the surrounding rock and soil temperature along the depth direction, and ensures the consistency between the input tunnel air temperature and the output tunnel air temperature through iteration, so that the obtained result is closer to the true value.

[0047] The method of this invention can obtain the evolution characteristics of air temperature and soil heat storage in subway sections of different representative cities over the years, which can provide technical support for the control and prediction of tunnel temperature in subway sections of different cities and for the energy-saving operation of air conditioning systems in stations and carriages during summer. Attached Figure Description

[0048] Figure 1 This is a flowchart of the iterative solution method of the present invention;

[0049] Figure 2 This is a diagram showing the initial annual and monthly temperature field of the surrounding rock and soil of the tunnel based on a scaled model experiment according to the present invention.

[0050] Figure 3 This is the first annual and monthly average temperature map of the tunnel section in Shanghai region input in this invention;

[0051] Figure 4 This is a model diagram of a subway station tunnel section simulated by the CHAMP-BES software of this invention;

[0052] Figure 5 This is a map showing the annual and monthly average temperature of tunnel sections in Shanghai under different levels of precision output during the three iterations of this invention.

[0053] Figure 6 This is a temperature difference diagram between the output and input of each iteration of the present invention;

[0054] Figure 7 This is a yearly and monthly average temperature map of the interval tunnel that evolves with the time limit based on iterative solution according to the present invention. Detailed Implementation

[0055] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0056] The specific implementation steps, taking Shanghai as an example, are as follows:

[0057] Step 1:

[0058] Firstly, the heat gain or loss in the tunnel section is the heat Q stored in the tunnel air. air (Q air =0 does not mean the air temperature is 0), mainly including the heat Q generated by train operation. train The effective heat exchange of piston air, Q wind Heat storage Q of surrounding rock and soil soil Therefore, a heat balance model for the inter-tunnel section can be derived:

[0059] Q train +Q wind +Q soil =Q air (1)

[0060] In the formula:

[0061] Q train —Heat generated during train operation (J)

[0062] Q wind —Effective heat exchange of piston air (J)

[0063] Q soil —Heat storage and release of surrounding rock and soil (J)

[0064] Q air —Heat stored in tunnel air (J)

[0065] Since the heat stored in the tunnel air is relatively small compared to the heat of other factors, the heat stored and released by the air inside the tunnel (i.e., Q) can be ignored. air When =0), the temperature solution formula (4) for the annual and monthly average air temperature of the interval tunnel is obtained based on the interval tunnel heat balance model formula (1). The derivation process of formula (4) is as follows:

[0066] Q wind =ρ air c p,air V(T out,air -T in,air (2)

[0067] Substituting formula (2) into formula (1), we get:

[0068] Q train +Q soil +ρ air c p,air V(T out,air -T in,air )=0 (3)

[0069] From formula (3):

[0070]

[0071] In the formula:

[0072] ρ air —Air density inside the tunnel (kg / m³) 3 )

[0073] c p,air —Specific heat capacity of air at constant pressure inside the tunnel (J / (kg·℃))

[0074] V – Effective ventilation rate of the piston ventilation shaft (m³) 3 )

[0075] T out,air —Tunnel exterior air temperature (°C)

[0076] T in,air —Tunnel interior air temperature (°C)

[0077] To obtain the average annual and monthly heat storage and release of the surrounding rock and soil in the Shanghai area, a scaled-down test platform for the tunnel was constructed. The measured tunnel air temperature in a typical year at Shanghai Railway Station was used as the boundary condition. A scaled-down model experiment was conducted using an enthalpy difference laboratory to test the air supply to the soil within the test platform. In the experiment, the monthly tunnel air temperature, which remained constant over the years, was used as the boundary condition for the air temperature of the soil within the test platform (tunnel air temperature exhibits an evolutionary characteristic of increasing over years, but measuring temperatures over 15 years is impractical; therefore, only one year's air temperature was measured, and this one-year air temperature was substituted into the iterative model as the air temperature remaining constant over 15 years. Finally, the air temperature over 15 years, evolving over the years, was calculated). The initial annual and monthly temperature fields of the tunnel surrounding rock and soil corresponding to the actual model for 15 action cycles are shown in the attached figure. Figure 2 As shown, Figure 2 The range of 0-20m indicates the thickness of the soil in the sidewall.

[0078] The initial annual and monthly temperature field of the surrounding rock and soil of the tunnel along the depth direction (e.g.) Figure 4 By integrating along the y-axis, the total heat storage of the surrounding rock and soil in each month can be obtained. By subtracting the total heat storage of the soil in the following month from the total heat storage of the previous month, the initial average heat storage and release of the surrounding rock and soil over the years can be obtained.

[0079] Substituting the initial annual and monthly average heat storage of the surrounding rock and soil in Shanghai obtained above into the temperature solution formula of equation (4), the initial annual and monthly average air temperature of the tunnel section used for the first input in the iteration process is obtained. The iterative solution principle is as follows:

[0080] According to previous research by the research group on the heat generation of trains operating in tunnels within a single train interval, the average heat generated in a tunnel section under a given train density is 44,119 kJ in months when the air conditioning is on, and 39,285 kJ in months when the air conditioning is off. The train density in Shanghai during different operating periods is shown in Table 1 below. train Equal to 44119 × number of trips, the average monthly air temperature outside Shanghai tunnels is shown in Table 2 below. The effective air exchange rate of the piston ventilation shafts in tunnels during the air-conditioning season in Shanghai is 50m³. 3 / s, the effective air exchange rate of the tunnel piston ventilation shaft in the non-air-conditioned season is 29.44m³ / s. 3 / s. Under normal pressure, the air density in the tunnel is 1.29 kg / m³. 3 The specific heat capacity of air at constant pressure is 1.005 J / (kg·℃). Based on the above, and the temperature solution formula of equation (4), we can calculate the initial annual and monthly average temperature of the tunnel section in Shanghai, as shown in the attached figure. Figure 3 As shown.

[0081] Table 1 Train Traffic Density During Different Operating Periods

[0082]

[0083] Table 2 Simulated values ​​of external meteorological temperature parameters of the tunnel

[0084]

[0085] Next, a subway station tunnel model was created in the CHAMP-BES simulation software: a model measuring 1000*50*1m was built. 3 The subway station tunnel model is attached. Figure 4 As shown, the simulated tunnel surrounding rock and soil mass is as follows: Figure 4 0.2*1*1000m inside 3 As shown in this section, the wind speed in the tunnel in the simulation software is selected as the equivalent wind speed inside the tunnel, which is 1.6 m / s; the physical properties of the surrounding rock and soil of the tunnel obtained from the scaled model experiment are used as the side boundary conditions of the soil, as shown in Table 3; among them, the concrete lining in Table 3 below is part of the simulated tunnel surrounding rock and soil structure.

[0086] Table 3. Soil physical properties in Shanghai

[0087]

[0088]

[0089] Step Two:

[0090] Using the initial annual and monthly average air temperature of the tunnel in Shanghai obtained in step one as the initial tunnel air temperature as the boundary condition input, the annual and monthly temperature field of the tunnel surrounding rock and soil evolving with the years can be simulated using CHAMP-BES software.

[0091] Step 3:

[0092] The temperature field of the tunnel surrounding rock and soil that evolves with the years, obtained in step two, is integrated along the depth direction to obtain the total heat storage of the surrounding rock and soil in each month as it evolves with the years. The difference is then calculated to obtain the average heat storage and release of the surrounding rock and soil in each month as it evolves with the years (the solution method for this step is the same as that for step one).

[0093] Step Four:

[0094] Substituting the average annual and monthly heat storage of the surrounding rock and soil mass, which evolves over time as obtained in step three, into the temperature calculation formula of equation (4), the first output of the average annual and monthly temperature of the tunnel section in Shanghai is obtained as shown in the attached figure. Figure 5 The first output result is shown in the image.

[0095] Step 5:

[0096] The annual and monthly average temperature of the Shanghai region in Step 4 is compared with the annual and monthly average temperature of the Shanghai region in Step 1, which is the first input of the interval tunnel. The resulting temperature difference for the first iteration is shown in the attached figure. Figure 6 As shown in (1) of the appendix. Figure 6 As shown in (1), we found that the average temperature of the tunnel in the first output year by year and month has a large error compared with the input. The temperature difference between the two is in the range of -6℃ to 6℃, and the error can reach up to 20%. Therefore, we determined that the two are inconsistent and a second iteration calculation is required.

[0097] The annual and monthly average temperatures of the tunnel sections in the Shanghai area, as initially output, were used as boundary conditions and input into the CHAMP-BES simulation software. Steps two through five were repeated, and the second output results are shown in the attached figure. Figure 5 The second output result and the temperature difference of the second iteration are shown in the attached figure. Figure 6 As shown in (2), it is obvious that the temperature difference in the second iteration is smaller than that in the first iteration, with a maximum error of 0.81%. However, this still does not meet the requirements. Therefore, the second output result is used as the boundary condition input into the CHAMP-BES simulation software to repeat steps two to five for the third iteration. The third output result is shown in the attached figure. Figure 5 The second output result and the temperature difference in the third iteration are shown in the attached figure. Figure 6 As shown in (3) of the diagram. The temperature difference accuracy of the third iteration is 10. -2At this point, the requirements are met, and it can be determined that the temperatures are approximately the same, indicating that the input tunnel air temperature and the output tunnel air temperature from the temperature solution formula (4) have reached consistency, and the iteration is terminated. At this point, the calculated output of the annual and monthly average air temperature of the interval tunnel evolving with the years is the actual interval tunnel air temperature under the interaction with the soil. The annual and monthly temperature field of the tunnel surrounding rock and soil evolving with the years obtained from the most recent simulation in step two is shown in the attached figure. Figure 7 As shown (0.1-50m in the figure represents the depth in the y-axis direction), by integrating the temperature field of the tunnel surrounding rock and soil that evolves with the years along the depth direction (y-axis direction), the total heat storage of the surrounding rock and soil in each month can be obtained as it evolves with the years. By subtracting the total heat storage of the soil in the following month from the total heat storage of the previous month, the actual average heat storage and release of the surrounding rock and soil that evolves with the years can be obtained.

[0098] From the appendix Figure 2 With appendix Figure 7 Comparison: Appendix Figure 2 In our study, we found that the overall trend of the initial annual and monthly temperature field of the tunnel surrounding rock obtained from the scaled-down model experiment was the same. The soil temperature distribution curves near the wall (at a depth of 0.1m, closest to the wall) all showed a periodic upward trend. (See attached image.) Figure 7 In the iterative solution, the maximum amplitude of the annual and monthly average air temperature of the tunnel over the years, as obtained, is approximately twice the maximum amplitude of the initial annual and monthly temperature field of the surrounding rock and soil. This is mainly because the continuous increase in tunnel air temperature leads to a continuous increase in the heat storage of the surrounding rock and soil, resulting in a continuous rise in the temperature field of the surrounding rock and soil. However, the scaled-down model experiment uses a constant tunnel air temperature for each month of the year to act on the surface of the surrounding rock and soil, neglecting the evolutionary characteristics of the tunnel air temperature over the years. Therefore, the amplitude of the initial annual and monthly temperature field of the surrounding rock and soil obtained from the scaled-down model experiment is smaller. Thus, the annual and monthly average air temperature of the tunnel over the years and the annual and monthly average heat storage and release of the surrounding rock and soil obtained through this iterative solution method are more in line with reality.

[0099] The above-described embodiments are merely one implementation of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims.

Claims

1. An iterative solution method for calculating the air temperature and the heat storage and release of surrounding rock and soil in a tunnel section, characterized in that, include: Step 1: Establish a heat balance model for the tunnel section and derive the temperature calculation formula for the annual and monthly average air temperature of the tunnel section: (4) In equation (4), —The density of air inside the tunnel, , —Specific heat capacity at constant pressure of air inside the tunnel, , —Effective air exchange rate of the piston ventilation shaft , —Tunnel exterior air temperature, , —Air temperature inside the tunnel, , To generate heat for train operation, , For the storage and release of heat in the surrounding rock and soil, ; A scaled-down test bench for tunnel sections was built, and the initial annual and monthly temperature field of the surrounding rock and soil of the tunnel was obtained by using the measured monthly tunnel air temperature of a certain region, which remained constant over the years. The initial annual and monthly temperature field of the surrounding rock and soil of the tunnel is obtained by solving the temperature solution formula, which is used as the input for the iteration process. A subway station tunnel model was established in a porous media soil heat transfer simulation software. The physical properties of the surrounding rock and soil of the tunnel were obtained through scaled-down model experiments and used as the side boundary conditions of the soil. Step 2: Input the initial annual and monthly average air temperature of the tunnel section as the tunnel air temperature boundary condition, input it into the porous media soil heat transfer simulation software, and calculate the annual and monthly temperature field of the tunnel surrounding rock and soil that evolves with the years through software simulation. Step 3: Integrate the temperature field of the tunnel surrounding rock and soil over the years to obtain the average heat storage and release of the surrounding rock and soil over the years. Step 4: Substitute the average heat stored and released by the surrounding rock and soil over the years into the temperature solution formula to obtain the average temperature of the tunnel over the years and months in the output of the iteration process. Step 5: Compare the annual and monthly average temperatures of the interval tunnels between the input and output during the iteration process; If the two are consistent, the iterative solution yields the annual and monthly average temperature of the interval tunnel evolving with the years and the annual and monthly average heat storage and release of the surrounding rock and soil evolving with the years. If the two are inconsistent, the annual and monthly average temperature of the tunnel in the output interval is used as the input boundary condition and substituted into steps two to five to iterate and solve again until the two are consistent. Then the annual and monthly average temperature of the tunnel in the output interval and the annual and monthly average heat storage and release of the surrounding rock and soil are obtained by iterative solution. The method for obtaining the initial annual and monthly temperature field of the tunnel surrounding rock in step one is as follows: A scaled-down test bench for the tunnel section was constructed. The measured tunnel air temperature of a typical year at a station in the region was used as the boundary condition for the surrounding rock and soil. A scaled-down model experiment was conducted on the air supply to the soil within the scaled-down test bench using an enthalpy difference laboratory. In the experiment, the monthly tunnel air temperature, which remained constant over the years, was used as the air temperature boundary condition for the soil within the scaled-down test bench. The initial annual and monthly temperature fields of the tunnel surrounding rock and soil corresponding to the actual model were obtained for multiple action periods.

2. The iterative solution method for calculating the air temperature and heat storage / release of surrounding rock and soil in a tunnel section according to claim 1, characterized in that, In Step 1, the initial annual and monthly temperature field of the tunnel surrounding rock and soil is calculated using a temperature solution formula to obtain the interval's initial annual and monthly average temperature of the tunnel, which is used as input in the iterative process. Specifically: By integrating the initial annual and monthly temperature field of the surrounding rock and soil along the depth direction, the total heat storage of the surrounding rock and soil in each month can be obtained. By subtracting the total heat storage of the soil in the following month from the total heat storage of the previous month, the average heat storage and release of the surrounding rock and soil in the initial annual and monthly can be obtained. The goal is to obtain the average heat density of tunnel sections under a given traffic density in the region during months when trains are operating with and without air conditioning; to obtain the train traffic density in the region during different operating periods; to obtain the effective ventilation rate of the piston ventilation shafts in tunnel sections during the air-conditioned season and the non-air-conditioned season in the region; and to obtain the tunnel air density and the specific heat capacity of air at constant pressure in the region. By using the actual data and temperature calculation formula, the initial annual and monthly average temperature of the input interval tunnel is obtained.

3. The iterative solution method for calculating the air temperature and heat storage / release of surrounding rock and soil in a tunnel section according to claim 1, characterized in that, The specific steps for creating a subway station tunnel model are as follows: Establish 1000 50 1 A model of a subway station tunnel section, with an internal depth of 0.

2. 1 1000 The simulated tunnel surrounding rock and soil mass was used, and the equivalent wind speed inside the tunnel was selected as 1.

6. The physical properties of the surrounding rock and soil of the tunnel were obtained through scaled-down model experiments and used as the side boundary conditions of the soil. In this case, part of the simulated tunnel surrounding rock and soil structure contained concrete lining.

4. The iterative solution method for calculating the air temperature and heat storage / release of surrounding rock and soil in a tunnel section according to claim 1, characterized in that, The heat balance model for the tunnel section in step one is as follows: (1) In equation (1), —Heat generated during train operation , —Effective heat exchange of piston air, , —The heat storage and release of the surrounding rock and soil , —The heat stored in the air in the tunnel, ; The derivation of the temperature calculation formula in step one is as follows: In the heat balance model of the tunnel section, the heat stored in the tunnel air is ignored, i.e. =0; by the theorem: (2) Substituting formula (2) into formula (1), we get: (3) From formula (3): (4) In equations (2), (3) and (4): —The density of air inside the tunnel, , —Specific heat capacity at constant pressure of air inside the tunnel, , —Effective air exchange rate of the piston ventilation shaft , —Tunnel exterior air temperature, , —Air temperature inside the tunnel, .

5. The iterative solution method for calculating the air temperature and heat storage / release of surrounding rock and soil in a tunnel section according to claim 1, characterized in that, Step three involves solving the temperature field of the tunnel surrounding rock and soil over time, month by month, to obtain the average heat storage and release of the surrounding rock and soil over time. The specific operation is as follows: By integrating the temperature field of the tunnel surrounding rock and soil along the depth direction year by year and month by year, the total heat storage of the surrounding rock and soil in each month can be obtained. By subtracting the total heat storage of the soil in the next month from the total heat storage of the previous month, the average heat storage and release of the surrounding rock and soil year by year and month by year can be obtained.

6. The iterative solution method for calculating the air temperature and heat storage / release of surrounding rock and soil in a tunnel section according to claim 1, characterized in that, When both conditions in step five are consistent, the solution method for obtaining the annual and monthly average air temperature of the tunnel evolving with the years and the annual and monthly average heat storage and release of the surrounding rock and soil evolving with the years is as follows: when both conditions are consistent, the output annual and monthly average air temperature of the tunnel evolving with the years is the actual air temperature of the tunnel under the interaction with the soil. At this point, by integrating the temperature field of the tunnel surrounding rock and soil that has evolved over the years along the depth direction, the total heat storage of the surrounding rock and soil in each month can be obtained. By subtracting the total heat storage of the soil in the following month from the total heat storage of the previous month, the average heat storage and release of the surrounding rock and soil over the years can be obtained.

7. The iterative solution method for calculating the air temperature and heat storage / release of surrounding rock and soil in a tunnel section according to claim 1, characterized in that, In step five, the method for comparing the annual and monthly average temperatures of the input and output interval tunnels during the comparison iteration process is to subtract the two to obtain the temperature difference.

8. The iterative solution method for calculating the air temperature and heat storage / release of surrounding rock and soil in a tunnel section according to claim 7, characterized in that, The method for determining whether the two are consistent in step five is: the accuracy of the maximum temperature difference is 10. -2 Therefore, the two can be considered to be the same.

9. The iterative solution method for calculating the air temperature and heat storage / release of surrounding rock and soil in a tunnel section according to claim 1, characterized in that, The software used for simulating the heat transfer of porous media in step two is CHAMP-BES, ANSYS, or COMSOL.

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