Partitioned cooling method and system for high-ground-temperature water-rich fault tunnel

Abstract

The invention provides a partitioned cooling method and system for a high-ground-temperature water-rich fault tunnel, and belongs to the technical field of tunnel construction cooling, and the method comprises the steps: S1, building a ventilation model of the high-ground-temperature water-rich fault tunnel by taking X meters away from a tunnel face in the tunnel as a cooling region; s2, the cooling conditions in the cooling area under the working conditions of different combined cooling measures are simulated through the high-ground-temperature water-rich fault tunnel ventilation model, and an average temperature change curve in the cooling area under the working conditions of different combined cooling measures is obtained; and S3, a combined cooling scheme is determined according to the average temperature change curve in the cooling area under the working conditions of different combined cooling measures, and cooling is conducted in the high-ground-temperature water-rich fault tunnel construction according to the combined cooling scheme. According to the method, cooling measures and combined cooling measures commonly adopted in high-ground-temperature water-rich fault tunnel construction are designed and researched, a combined cooling scheme is formed, cooling is conducted in the high-ground-temperature water-rich fault tunnel construction, and theoretical reference is provided for cooling measure selection of a construction site.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel construction cooling, and relates to the cooling technology of high geothermal water-rich fault tunnels, in particular to a zoning cooling method and system for high geothermal water-rich fault tunnels. Background Art

[0002] With the continuous progress of the construction of the Sichuan-Tibet Railway, the construction problems of high geothermal tunnels have gradually become major problems hindering the project construction. Compared with ordinary tunnel construction, the high geothermal conditions bring many problems to tunnel construction, such as: personnel suffering from heat stroke due to the high-temperature environment, the efficiency of mechanical equipment being reduced, the strength of surrounding rocks and linings being weakened, and the development of rock bursts becoming faster. These problems seriously affect the safety of high geothermal tunnel construction. Among them, high geothermal tunnels passing through high-temperature water-rich faults are one of the difficulties in high geothermal problems due to characteristics such as large fissure water volume, high surrounding rock temperature, and complex heat supply sources.

[0003] During the construction stage of high geothermal tunnels, ventilation is one of the most important links, which has the functions of cooling the working area of the tunnel, supplying oxygen, diluting toxic gases, and accelerating dust settlement. Especially for high geothermal tunnels with relatively low surrounding rock temperature and single heat supply, increasing the ventilation volume can effectively reduce the average temperature of the tunnel working area. However, for many high geothermal tunnels with large burial depth, high temperature, and complex external heat supply that appear during the construction of the Sichuan-Tibet Railway, simple ventilation cooling is difficult to reduce the tunnel temperature to 28°C specified in the "Code for Design of Railway Tunnels". At this time, corresponding combined cooling measures are often taken, that is, auxiliary measures such as spray cooling, ice block cooling, and local refrigeration are taken in cooperation with ventilation cooling measures. However, in actual work, it is difficult for technicians to determine the timing of taking combined cooling measures. If combined cooling measures are taken when the temperature is too low, it will cause waste of resources; if combined cooling measures are taken when the temperature is too high, it will affect the cooling effect. Therefore, it is necessary to carry out research on the temperature control measures during the construction period in the thermal environment of high geothermal water-rich fault tunnels. Summary of the Invention

[0004] Aiming at the technical problem described in the above background art that it is difficult to determine the timing of taking combined cooling measures in the construction of high geothermal water-rich fault tunnels, the invention proposes a zoning cooling method and system for high geothermal water-rich fault tunnels.

[0005] The invention designs and researches the cooling measures and combined cooling measures commonly used in the construction of high geothermal water-rich fault tunnels, so as to form a combined cooling plan, through which technicians can clarify the specific combined cooling measures and the timing of taking combined cooling measures, and carry out cooling during the construction of high geothermal water-rich fault tunnels according to the combined cooling plan, providing a theoretical reference for the selection of cooling measures at the construction site.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for zoned cooling of a high geothermal water-rich fault tunnel in the present invention includes the following steps:

[0008] S1: Taking the area X meters away from the tunnel face in the tunnel as the cooling area, establish a ventilation model for the high geothermal water-rich fault tunnel;

[0009] S2: Respectively simulate the cooling conditions in the cooling area under different combined cooling measures through the ventilation model of the high geothermal water-rich fault tunnel, and obtain the average temperature change curves in the cooling area under different combined cooling measures;

[0010] S3: Determine the combined cooling scheme according to the average temperature change curves in the cooling area under different combined cooling measures, and perform cooling during the construction of the high geothermal water-rich fault tunnel according to the combined cooling scheme.

[0011] Further defined, the step S1 is specifically:

[0012] S1.1: Taking the area X meters away from the tunnel face in the tunnel as the cooling area, establish an initial model for the high geothermal water-rich fault tunnel;

[0013] S1.2: Set a single-duct jet ventilation model in the initial model of the high geothermal water-rich fault tunnel to form a ventilation model for the high geothermal water-rich fault tunnel.

[0014] Further defined, the step S2 is specifically:

[0015] S2.1: Set the initial conditions and boundary conditions in the ventilation model of the high geothermal water-rich fault tunnel, adopt ventilation cooling measures for cooling, ventilate and cool for 30 minutes in the cooling area, and obtain the average temperature change curves in the cooling area when the initial temperature of the tunnel surrounding rock is at different set initial temperature points, as the first group of average temperature change curves;

[0016] S2.2: Set ice blocks in the ventilation model of the high geothermal water-rich fault tunnel, adopt a combined cooling measure of ventilation + ice blocks for cooling, combine and cool for 30 minutes in the cooling area, and obtain the average temperature change curves in the cooling area when the initial temperature of the tunnel surrounding rock is at different set initial temperature points, as the first group of combined cooling average temperature change curves;

[0017] S2.3: Set nozzles in the ventilation model of the high geothermal water-rich fault tunnel, adopt a combined cooling measure of ventilation + spraying for cooling, combine and cool for 30 minutes in the cooling area, and obtain the average temperature change curves in the cooling area when the initial temperature of the tunnel surrounding rock is at different set initial temperature points, as the second group of combined cooling average temperature change curves;

[0018] S2.4: Based on the first group of average temperature change curves, the first group of combined cooling average temperature change curves, and the second group of combined cooling average temperature change curves, average temperature change curves in the cooling area under different combined cooling measures are formed.

[0019] It is further defined that the ventilation+spray combination cooling measure includes a variety of combined cooling measures formed by ventilation+spray combination of multiple nozzles.

[0020] It is further defined that the different set initial temperature points are 35°C, 45°C, 55°C, 65°C, 75°C and 85°C.

[0021] It is further defined that the boundary conditions of the high geothermal water-rich fault tunnel ventilation model are as follows: the front boundary, the rear boundary, the left boundary and the right boundary are all adiabatic walls, the upper boundary is the temperature boundary, and the lower boundary is the heat flux density boundary.

[0022] Further definition, the initial conditions of the high geothermal water-rich fault tunnel ventilation model are: ventilation volume is 37.10m 3 / s, wind temperature is 23℃, and initial temperature range is 28℃-85℃.

[0023] It is further defined that the size of the initial model of the high geothermal water-rich fault tunnel is 120m×50m×50m; the fault width of the initial model of the high geothermal water-rich fault tunnel is 20m, wherein the velocity inlet is above the fault, using the fissure water flow velocity, and the pressure outlet is below the fault; the angle between the initial model of the high geothermal water-rich fault tunnel and the horizontal direction is 60°.

[0024] The invention discloses a zoned cooling system for a high geothermal water-rich fault tunnel, comprising a high geothermal water-rich fault tunnel ventilation model and a cooling module.

[0025] The high geothermal water-rich fault tunnel ventilation model is established with the cooling area X meters away from the tunnel face as the cooling area, which is used to simulate the cooling conditions in the cooling area under different combined cooling measures, and obtain the average temperature change curve in the cooling area under different combined cooling measures.

[0026] The cooling module is used to determine a combined cooling scheme according to an average temperature change curve in a cooling area under different combined cooling measures, and to perform cooling in the construction of a high geothermal water-rich fault tunnel according to the combined cooling scheme.

[0027] It is further defined that the different combined cooling measures are formed by different combined cooling devices, and the different combined cooling devices include ventilation cooling devices, ice cooling devices and spray cooling devices.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] A method for zoning temperature reduction in a high geothermal water-rich fault tunnel of the present invention designs and studies the temperature reduction measures and combined temperature reduction measures commonly used in the construction of high geothermal water-rich fault tunnels, selects a specific area (X meters away from the tunnel face in the tunnel) as the temperature reduction area, so as to achieve zoning temperature reduction; at the same time, through the ventilation model of the high geothermal water-rich fault tunnel, the temperature reduction situation in the temperature reduction area under different combined temperature reduction measures is obtained, and the average temperature change curve in the temperature reduction area under different combined temperature reduction measures is obtained, and then the combined temperature reduction scheme is determined to cool the high geothermal water-rich fault tunnel, providing a theoretical reference for the selection of temperature reduction measures at the construction site. Description of the Drawings

[0030] Figure 1 It is a schematic diagram of the ventilation model of the high geothermal water-rich fault tunnel;

[0031] Figure 2 It is the temperature field nephogram in the temperature reduction area with different initial rock temperatures. Among them, the initial rock temperature of (a) is 35 °C, the initial rock temperature of (b) is 45 °C, the initial rock temperature of (c) is 55 °C, the initial rock temperature of (d) is 65 °C, the initial rock temperature of (e) is 75 °C, and the initial rock temperature of (f) is 85 °C;

[0032] Figure 3 It is the first group of average temperature change curves;

[0033] Figure 4 It is the relationship curve between the initial rock temperature and the stable temperature in the temperature reduction area;

[0034] Figure 5 It is a schematic diagram of setting ice cubes in the ventilation model of the high geothermal water-rich fault tunnel;

[0035] Figure 6 It is the average temperature change curve in the temperature reduction area with different ice cube dosages;

[0036] Figure 7 It is the temperature field nephogram of the cross section where the ice cubes are located in the stable state tunnel under different initial rock temperatures. Among them, the initial rock temperature of (a) is 35 °C, the initial rock temperature of (b) is 45 °C, the initial rock temperature of (c) is 55 °C, the initial rock temperature of (d) is 65 °C, the initial rock temperature of (e) is 75 °C, and the initial rock temperature of (f) is 85 °C;

[0037] Figure 8 It is the first group of combined temperature reduction average temperature change curves (ventilation + ice cube combined temperature reduction measures);

[0038] Figure 9Schematic diagram of setting four nozzles (condition 1) in the ventilation model of high geothermal water-rich fault tunnel;

[0039] Figure 10 Schematic diagram of setting eight nozzles (condition 2) in the ventilation model of high geothermal water-rich fault tunnel;

[0040] Figure 11 Top view of the droplet distribution in the ventilation model of high geothermal water-rich fault tunnel, where (a) is condition 1 and (b) is condition 2;

[0041] Figure 12 Contour map of the temperature field of the longitudinal section in the ventilation model of high geothermal water-rich fault tunnel, where (a) is condition 1, (b) is condition 2, and (c) is without spraying;

[0042] Figure 13 Contour map of the temperature field of the longitudinal section of a single air duct, where (a) is condition 1, (b) is condition 2, and (c) is without spraying;

[0043] Figure 14 Average temperature change curve of the second group of combined cooling (condition 1);

[0044] Figure 15 Average temperature change curve of the second group of combined cooling (condition 2);

[0045] Figure 16 Relationship curve between the initial temperature of the surrounding rock and the stable temperature in the cooling area under the combined cooling measures of ventilation + spraying (condition 1);

[0046] Figure 17 Relationship curve between the initial temperature of the surrounding rock and the stable temperature in the cooling area under the combined cooling measures of ventilation + spraying (condition 2). Detailed implementation method

[0047] The technical solution of the present invention will be further explained below in conjunction with the drawings and embodiments, but the present invention is not limited to the following described embodiments.

[0048] A zoning cooling method for high geothermal water-rich fault tunnels of the present invention includes the following steps:

[0049] S1: Taking the area X meters away from the tunnel face in the tunnel as the cooling area, a ventilation model of the high geothermal water-rich fault tunnel is established;

[0050] S2: By simulating the cooling conditions in the cooling area under different combined cooling measure conditions through the ventilation model of the high geothermal water-rich fault tunnel, the average temperature change curves in the cooling area under different combined cooling measure conditions are obtained;

[0051] S3: Determine the combined cooling scheme according to the average temperature change curve in the cooling area under the conditions of different combined cooling measures, and carry out cooling during the construction of high geothermal water-rich fault tunnels according to the combined cooling scheme.

[0052] Among them, step S1 is specifically as follows:

[0053] S1.1: Take the area X meters away from the tunnel face in the tunnel as the cooling area, and establish an initial model of the high geothermal water-rich fault tunnel.

[0054] S1.2: Set up a single-duct jet ventilation model in the initial model of the high geothermal water-rich fault tunnel to form a ventilation model of the high geothermal water-rich fault tunnel.

[0055] Among them, step S2 is specifically as follows:

[0056] S2.1: Set the initial conditions and boundary conditions in the ventilation model of the high geothermal water-rich fault tunnel, and use the ventilation cooling measure to cool down. Cool down for 30 minutes in the cooling area, and obtain the average temperature change curve in the cooling area when the initial temperature of the tunnel surrounding rock is at different set initial temperature points, which is used as the first group of average temperature change curves.

[0057] S2.2: Set ice cubes in the ventilation model of the high geothermal water-rich fault tunnel, and use the combined cooling measure of ventilation + ice cubes to cool down. Cool down for 30 minutes in the cooling area, and obtain the average temperature change curve in the cooling area when the initial temperature of the tunnel surrounding rock is at different set initial temperature points, which is used as the first group of combined cooling average temperature change curves.

[0058] S2.3: Set nozzles in the ventilation model of the high geothermal water-rich fault tunnel, and use the combined cooling measure of ventilation + spraying to cool down. Cool down for 30 minutes in the cooling area, and obtain the average temperature change curve in the cooling area when the initial temperature of the tunnel surrounding rock is at different set initial temperature points, which is used as the second group of combined cooling average temperature change curves.

[0059] S2.4: Based on the first group of average temperature change curves, the first group of combined cooling average temperature change curves and the second group of combined cooling average temperature change curves, form the average temperature change curve in the cooling area under the conditions of different combined cooling measures.

[0060] Preferably, the combined cooling measure of ventilation + spraying includes various combined cooling measures formed by ventilation + combined spraying with multiple nozzles. For example: the combined cooling measure formed by ventilation + combined spraying with four nozzles, the combined cooling measure formed by ventilation + combined spraying with eight nozzles, the combined cooling measure formed by ventilation + combined spraying with 16 nozzles, the combined cooling measure formed by ventilation + combined spraying with three nozzles, the combined cooling measure formed by ventilation + combined spraying with six nozzles, the combined cooling measure formed by ventilation + combined spraying with nine nozzles.

[0061] A method for zoning cooling of a high geothermal water-rich fault tunnel in the present invention is based on the energy conservation theory to determine the heat dissipation of the high geothermal water-rich fault tunnel and the heat absorption value Δ of the cooling measures Q1 should satisfy:

[0062] Δ Q1 = Q1 + Q2 + Q3 + Q4 - q<0

[0063] In the formula, Q1 is the heat dissipation of the surrounding rock; Q2 is the heat release of the high-temperature water in the fault; Q3 is the heat release of the mechanical equipment in the tunnel; Q4 is the heat release of the construction personnel in the tunnel; q is the heat absorption of the cooling measures or combined cooling measures.

[0064] According to the change curve of Δ Q1 and the initial temperature of the surrounding rock, set the initial conditions in the ventilation model of the high geothermal water-rich fault tunnel.

[0065] The steps of a method for zoning cooling of a high geothermal water-rich fault tunnel in the present invention will be specifically described below:

[0066] Refer to Figure 1 , taking 30 meters from the tunnel face as the cooling area for zoning; 30 meters from the tunnel face is the most unfavorable working condition, so 30 meters from the tunnel face is selected as the cooling area.

[0067] Use FLUENT software to establish an initial model of the high geothermal water-rich fault tunnel, and at the same time set a single-duct jet ventilation model in the initial model of the high geothermal water-rich fault tunnel to form a ventilation model of the high geothermal water-rich fault tunnel. Among them, the size of the initial model of the high geothermal water-rich fault tunnel is 120m × 50m × 50m, the fault width of the initial model of the high geothermal water-rich fault tunnel is 20m, the velocity inlet is above the fault, and the fissure water flow velocity is adopted. The pressure outlet is below the fault, and the included angle between the initial model of the high geothermal water-rich fault tunnel and the horizontal direction is 60°.

[0068] Set the initial conditions and boundary conditions in the ventilation model of the high geothermal water-rich fault tunnel. Among them, the boundary conditions are: the front boundary, rear boundary, left boundary, and right boundary are all adiabatic walls, the upper boundary is the temperature boundary, and the lower boundary is the heat flux density boundary; the initial conditions are: the ventilation volume is 37.10m 3 / s, the air temperature is 23 °C, the initial temperature range is 28 °C - 85 °C, and the transient calculation time is 10 years.

[0069] Adopt ventilation cooling measures for cooling, ventilate and cool in the cooling area for 30 minutes, and obtain the average temperature change curves in the cooling area when the initial temperatures of the surrounding rock are 35 °C, 45 °C, 55 °C, 65 °C, 75 °C, and 85 °C respectively, as the first group of average temperature change curves.

[0070] Set ice blocks in the ventilation model of the high geothermal water-rich fault tunnel, and adopt the combined cooling measures of ventilation + ice blocks for cooling. Cool for 30 minutes in the cooling area, and obtain the average temperature change curves in the cooling area when the initial temperatures of the tunnel surrounding rock are 35°C, 45°C, 55°C, 65°C, 75°C, and 85°C respectively, which are used as the average temperature change curves of the first group of combined cooling.

[0071] Set four nozzles in the ventilation model of the high geothermal water-rich fault tunnel, and adopt the combined cooling measures of ventilation + spraying for cooling. Cool for 30 minutes in the cooling area, and obtain the average temperature change curves in the cooling area when the initial temperatures of the tunnel surrounding rock are 35°C, 45°C, 55°C, 65°C, 75°C, and 85°C respectively, which are used as the average temperature change curves of the second group of combined cooling (working condition 1).

[0072] Set eight nozzles in the ventilation model of the high geothermal water-rich fault tunnel to form four groups, and adopt the combined cooling measures of ventilation + spraying for cooling. Cool for 30 minutes in the cooling area, and obtain the average temperature change curves in the cooling area when the initial temperatures of the tunnel surrounding rock are 35°C, 45°C, 55°C, 65°C, 75°C, and 85°C respectively, which are used as the average temperature change curves of the second group of combined cooling (working condition 2).

[0073] Based on the first group of average temperature change curves, the average temperature change curves of the first group of combined cooling, and the average temperature change curves of the second group of combined cooling, form the average temperature change curves in the cooling area under different combined cooling measure working conditions.

[0074] Determine the combined cooling scheme according to the average temperature change curves in the cooling area under different combined cooling measure working conditions. Among them, the combined cooling scheme is shown in Table 1.

[0075] Table 1: Combined cooling scheme

[0076]

[0077] (1) Research on ventilation cooling measures

[0078] After ventilation for 30 minutes, the temperature field in the cooling area is basically stable. The area 30 meters away from the tunnel face in the tunnel is the main working area. Select ventilation for 30 minutes under different initial temperatures of the surrounding rock as the research object, and the temperature cloud map of the formed cooling area is as Figure 2 shown.

[0079] From Figure 2 the (a)-(f) in it, it can be seen that the change in the initial temperature of the surrounding rock does not change the distribution form of the temperature field after the high geothermal water-rich fault tunnel is stable. The higher the initial temperature of the surrounding rock, the higher the temperature at a certain point in the cooling area, and the temperature in the area 20 meters away from the tunnel face in the tunnel is relatively low.

[0080] See Figure 3 and Figure 4 , taking the stable temperature in the cooling area after 30 minutes of ventilation as the research object, extracting the first group of average temperature change curves and the relationship curve between the initial temperature of the surrounding rock and the stable temperature in the cooling area, through Figure 3 and Figure 4 It can be seen that after a period of ventilation, the cooling areas of high geothermal tunnels passing through high-temperature and water-rich faults all maintain a relatively stable temperature. At this time, the heat dissipation and heat absorption inside the high geothermal and water-rich fault tunnels are basically the same, reaching a relatively balanced state. As the initial temperature of the surrounding rock increases, not only does the average time to reach a stable state in the area 30 meters away from the tunnel face become longer, but also the cooling value and the stable temperature value in the area 30 meters away from the tunnel face increase.

[0081] From Figure 3 and Figure 4 it can be seen that when the initial temperature of the surrounding rock of a high geothermal tunnel passing through a high-temperature and water-rich fault exceeds 37.6 °C, it is difficult to support the temperature in the tunnel working area to drop to the required 28 °C only by ventilation cooling.

[0082] (2) Research on the combined cooling measures of ventilation + ice cubes

[0083] On the basis of the research on ventilation cooling measures, ice cubes are set in the ventilation model of high geothermal and water-rich fault tunnels. The thermal parameters of the ice-water material are shown in Table 2.

[0084] Table 2: Thermal parameters of ice-water at 0 °C and 1 standard atmosphere

[0085] Solid-phase temperature of water (°C) Liquid-phase temperature of water (°C) Heat of fusion of ice (J / g) 0 0 333.146

[0086] There are many factors affecting the cooling effect of ice cubes, such as the amount of ice cubes, the spatial position of ice cubes placed in the tunnel, the shape of ice cubes, etc. According to the size of ice cubes produced by the on-site ice factory and the suggestions for the placement position of ice cubes in relevant research, in this paper, ice cubes with a specification of 0.5m×1m×2m are placed 2m higher, and the calculation model is as Figure 5 shown.

[0087] See Figure 6 , taking the initial temperature of the surrounding rock of 65 °C as an example, monitoring the average temperature change curves in the cooling area when the amounts of ice cubes are 0.5 tons, 1 ton, 1.5 tons, and 2 tons respectively. From Figure 6It can be seen that the greater the amount of ice used, the lower the average temperature in the cooling area. Adding 0.5t of ice on the basis of ventilation can make the temperature field in the cooling area enter a stable state 4 minutes earlier. After 6 minutes, the average temperature is lower than 28°C required for construction. And the average temperature in this cooling area is 7.6°C lower than that without adding ice. After 26 minutes of ventilation, the average temperature in the cooling area is higher than 28°C again. This is because during the cooling process, the ice gradually melts and the mass M of the ice decreases to a certain threshold, resulting in a decline in the cooling capacity. When the ice mass M≥1t, there is no upward trend in temperature in the first 30 minutes of cooling. As the amount of ice used increases, the time for the average temperature in the cooling area to reach the equilibrium state continuously decreases. When the ice mass M increases from 0.5t to 1t, the average temperature in the cooling area decreases by 5.1°C more. However, when the ice mass increases from 1.5t to 2t, the average temperature at the stable state of the cooling area only decreases by 1.2°C more. This is because the heat absorption capacity of the ice is related to its surface area. The accumulation of ice leads to a decrease in the specific surface area of the ice, and the increase in the ice volume may also change the variation of the tunnel flow field. Therefore, the cooling capacity of the ice does not show a linear positive correlation with the amount of ice used.

[0088] The above temperature change law shows that the combined cooling measure of ventilation + ice has the ability to reduce the temperature in the cooling area below 28°C in a short time. Increasing the amount of ice used, the lower the average temperature at the stable state in the cooling area, and the longer the duration of cooling, but the improved cooling capacity is limited.

[0089] Based on the above conclusions, considering the on-site conditions and economic benefits, the condition of ventilation + ice (1t) is selected for research, and the temperature field nephogram of the cross-section where the tunnel ice is located at the stable state under different initial surrounding rock temperature conditions is extracted, as Figure 7 shown. The curve of the average temperature in the cooling area changing with time under different initial surrounding rock temperature conditions for the condition of ventilation + ice (1t) is selected, as Figure 8 shown.

[0090] The lower the initial surrounding rock temperature, the lower the average temperature in the cooling area; the cooling range of the ice is limited, and it has a significant impact on the temperature field within a distance of 3 - 4m near the ice. Affected by the cold air flow in the tunnel, the influence range of the ice on the single-air duct side is significantly larger than that on the opposite side of the single-air duct. Combining Figure 7 and Figure 8It can be seen that when the initial temperature of the surrounding rock T = 85°C, the cooling capacity begins to weaken after 24 minutes; when T = 75°C, the cooling capacity begins to weaken after 26 minutes; when T ≤ 65°C, there is no significant increase in the back end of the temperature change curve before 30 minutes, and the cooling capacity does not weaken. When the initial temperature of the surrounding rock is relatively small (T ≤ 55°C), the average temperature difference in the stable cooling area is not large. The above rules show that when the temperature of the surrounding rock T > 65°C, the measure of using ice cubes (1t) to assist ventilation and cooling is not suitable, and it is considered to increase the amount of ice cubes or consider other auxiliary cooling measures.

[0091] (3) Research on the combined cooling measure of ventilation + spraying

[0092] Based on the research of the ventilation cooling measure, referring to Figure 9 and Figure 10 , spray cooling is realized on the basis of tunnel ventilation. First, set the parameters and boundary conditions for the continuous phase flow field of the combined model, solve the phase flow field until convergence, then turn on the discrete phase model, set the relevant parameters of the particle flow in the converged flow field, set the discrete phase parameters, boundary conditions, etc., and calculate the coupled field of the discrete phase and the continuous phase. The spray parameters are selected as shown in Table 3.

[0093] Table 3: Spray parameters

[0094]

[0095] Two spray forms are selected respectively:

[0096] Condition 1: Referring to Figure 9 , 4 nozzles are used, and the nozzles are arranged directly above the tunnel and evenly distributed in the area 30 meters away from the tunnel face in the tunnel, with a spacing of 6m, and the nozzle mouth is 1m away from the vault.

[0097] Condition 2: Referring to Figure 10 , 8 nozzles are used, and the nozzles are arranged in two rows, a total of four groups. The spacing between the nozzles in the same row is 6m, the spacing between the two rows of nozzles is 5m, and the nozzle mouth is 1.5m away from the vault.

[0098] Taking the surrounding rock temperature of 65°C as an example, the droplet distributions of the spray in Condition 1 and Condition 2 are as Figure 11 shown.

[0099] As can be seen from the above figure, the spraying range of a single spray is limited, and spray cooling is more suitable for centralized cooling in a certain limited area to meet the need for effective cooling in the construction cooling for the cooling area. By comparing the droplet distribution in Working Condition 1 and Working Condition 2, it can be seen that: more droplets in Working Condition 1 gather in the central area of the tunnel, and the droplets tend to be adsorbed by the ventilation air current under the influence of the ventilation air current, resulting in a better local cooling effect in the central area of the tunnel. The droplet distribution in Working Condition 2 is wider, and the spraying influence range is larger. The spray particles on the single air duct side are affected by the cold air current of the air duct, and have a greater offset distance in the axial direction of the tunnel compared to the droplets on the opposite side of the single air duct. The droplets are blocked at the heading face, so more droplets gather in the heading face area.

[0100] Extract the temperature cloud maps of the cooling areas in Working Condition 1 and Working Condition 2 when the initial temperature of the surrounding rock is 65℃ according to the calculation results as Figure 12 and Figure 13 shown. From the temperature field cloud map, it can be seen that the temperature in the cooling area with spray assistance is significantly lower than that in the cooling area under the ventilation-only condition. Compared with the temperature field distribution in the cooling area without spray, the temperature in the cooling area after spray is significantly reduced by about 8.1℃, and the temperature distribution also changes from "cold at the top and hot at the bottom" without spray to basically the same temperature up and down.

[0101] See Figure 14 and Figure 15 , by monitoring the temperature in the area 30 meters away from the heading face in the tunnel, draw the second group of combined cooling average temperature change curves (Working Condition 1) and the second group of combined cooling average temperature change curves (Working Condition 2). From Figure 14 and Figure 15 it can be seen that the higher the initial temperature of the surrounding rock, the more time it takes for the cooling area to reach the stable temperature. Taking the surrounding rock temperature of 85℃ as an example, in the case of Working Condition 1, the temperature in the cooling area is basically stable after 9 minutes of cooling, and the average temperature remains basically unchanged after reaching the stable state. While in the case of Working Condition 2, the average temperature in the cooling area does not tend to be stable until 12 minutes, and the temperature field enters the stable state, and there is still a little fluctuation in the average temperature after the temperature field in the cooling area enters the stable state. From the same working condition, the higher the initial temperature of the surrounding rock, the faster the cooling rate and the greater the cooling amplitude in the initial stage of cooling. From Figure 14 and Figure 15It can also be seen that the initial temperature of the surrounding rock affects the average temperature in the cooling area after it stabilizes. The higher the initial temperature of the surrounding rock, the higher the average temperature in the cooling area after reaching stability. Analyzing the time-history curve in the steady state stage of working condition 1, when the initial temperature of the surrounding rock decreases from 85 °C to 75 °C, the average temperature in the cooling area decreases by 3 °C after the temperature field reaches equilibrium. While when the initial temperature of the surrounding rock decreases from 45 °C to 35 °C, the average temperature in the cooling area only decreases by 0.5 °C after equilibrium. This indicates that when the initial temperature of the surrounding rock is relatively low, the effect of spray cooling is basically the same, and when the initial temperature of the surrounding rock is relatively high, the difference in the effect of spray cooling is relatively large.

[0102] Taking the average temperature in the cooling area after 30 minutes of cooling as the research object, the relationship curves between the initial temperature of the surrounding rock and the stable temperature in the cooling area for working condition 1 and working condition 2 are plotted, as Figure 16 and Figure 17 shown. From Figure 16 and Figure 17 the following conclusions can be drawn: Spray cooling is an effective auxiliary construction cooling method that can effectively locally cool the cooling area in a short time. Working condition 1 with four nozzles can reduce the cooling area to a stable state in a shorter time, but the final stable temperature is relatively high; when the initial temperature of the surrounding rock exceeds 67 °C, working condition 1 cannot meet the requirement of 28 °C for construction; working condition 2 with eight nozzles has a better cooling effect on the cooling area, and the average temperature in the cooling area after stability is 4 - 7 °C lower than that of working condition 1 under the same initial temperature conditions of the surrounding rock. The tunnel passing through the high-temperature and water-rich fault within the temperature range of 35 - 85 °C for the initial temperature of the surrounding rock can reach the highest construction environment temperature of 28 °C after a period of spray-assisted ventilation measures.

[0103] Combining the research on ventilation cooling measures, the research on ventilation + ice block combined cooling measures, and the research on ventilation + spray combined cooling measures, a combined cooling plan as shown in Table 1 is formed, and cooling is carried out during the construction of the high-temperature ground water-rich fault tunnel through this combined cooling plan.

[0104] A partition cooling system for a high-temperature ground water-rich fault tunnel of the present invention includes a ventilation model for the high-temperature ground water-rich fault tunnel and a cooling module.

[0105] The ventilation model for the high-temperature ground water-rich fault tunnel is established with the area X meters away from the tunnel face in the tunnel as the cooling area, and is used to respectively simulate the cooling situation in the cooling area under different combined cooling measure conditions, and obtain the average temperature change curve in the cooling area under different combined cooling measure conditions.

[0106] The cooling module is used to determine the combined cooling plan according to the average temperature change curve in the cooling area under different combined cooling measure conditions, and carry out cooling during the construction of the high-temperature ground water-rich fault tunnel according to the combined cooling plan.

[0107] The different combined cooling measures are formed by different combined cooling devices. The different combined cooling devices include a ventilation cooling device, an ice cooling device, and a spray cooling device. Among them, the ventilation cooling device is a single-duct jet fan; see Figure 5 , the ice cooling device includes a support platform and ice blocks located above the support platform. The ice blocks are raised 2 m by the support platform, and the specifications of the ice blocks are 0.5 m × 1 m × 2 m; the spray cooling device refers to spraying water atomization by arranging nozzles at the top of the high geothermal water-rich fault tunnel. There are multiple ways of nozzle combination, such as: four-nozzle combination, eight-nozzle combination, 16-nozzle combination, three-nozzle combination, six-nozzle combination, or nine-nozzle combination, etc.

[0108] It should be noted that the working area in the specification drawings refers to the cooling area in the content.

[0109] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting the present invention; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present invention.

Claims

1. A method for zoning cooling of a high geothermal water-rich fault tunnel, characterized in that, It includes the following steps: S1: Taking the area X meters away from the tunnel face in the tunnel as the cooling area, establish a ventilation model for high geothermal water-rich fault tunnels; S2: Through the ventilation model of high geothermal water-rich fault tunnels, simulate the cooling conditions in the cooling area under different combinations of cooling measures, and obtain the average temperature change curves in the cooling area under different combinations of cooling measures; S3: Determine the combined cooling scheme according to the average temperature change curves in the cooling area under different combinations of cooling measures, and carry out cooling during the construction of high geothermal water-rich fault tunnels according to the combined cooling scheme.

2. The method for zoned cooling of high geothermal water-rich fault tunnels according to claim 1, characterized in that The specific content of step S1 is as follows: S1.1: Taking the area X meters away from the tunnel face in the tunnel as the cooling area, establish an initial model for high geothermal water-rich fault tunnels; S1.2: Set a single-duct jet ventilation model in the initial model of high geothermal water-rich fault tunnels to form a ventilation model for high geothermal water-rich fault tunnels.

3. The method for zonal cooling of high geothermal water-rich fault tunnels according to claim 1, characterized in that The specific content of step S2 is as follows: S2.1: Set the initial conditions and boundary conditions in the ventilation model of high geothermal water-rich fault tunnels, adopt ventilation cooling measures for cooling, ventilate and cool for 30 minutes in the cooling area, and obtain the average temperature change curves in the cooling area when the initial temperature of the tunnel surrounding rock is at different set initial temperature points, which are used as the first group of average temperature change curves; S2.2: Set ice blocks in the ventilation model of high geothermal water-rich fault tunnels, adopt a combined cooling measure of ventilation + ice blocks for cooling, carry out combined cooling for 30 minutes in the cooling area, and obtain the average temperature change curves in the cooling area when the initial temperature of the tunnel surrounding rock is at different set initial temperature points, which are used as the first group of combined cooling average temperature change curves; S2.3: Set nozzles in the ventilation model of high geothermal water-rich fault tunnels, adopt a combined cooling measure of ventilation + spraying for cooling, carry out combined cooling for 30 minutes in the cooling area, and obtain the average temperature change curves in the cooling area when the initial temperature of the tunnel surrounding rock is at different set initial temperature points, which are used as the second group of combined cooling average temperature change curves; S2.4: Based on the first group of average temperature change curves, the first group of combined cooling average temperature change curves and the second group of combined cooling average temperature change curves, form the average temperature change curves in the cooling area under different combinations of cooling measures.

4. The method for zoning temperature reduction of high geothermal water-rich fault tunnels according to claim 3, characterized in that The combined cooling measure of ventilation + spraying includes multiple combined cooling measures formed by ventilation + spraying with multiple nozzle combinations.

5. The method for zonal cooling of a high geothermal water-rich fault tunnel according to claim 3, characterized in that, The different set initial temperature points are 35°C, 45°C, 55°C, 65°C, 75°C and 85°C.

6. The method for zoning temperature reduction of a high geothermal water-rich fault tunnel according to claim 3, characterized in that, The boundary conditions of the ventilation model of high geothermal water-rich fault tunnels are: the front boundary, the rear boundary, the left boundary and the right boundary are all adiabatic wall surfaces, the upper boundary is a temperature boundary, and the lower boundary is a heat flux density boundary.

7. The method for zoned cooling of high geothermal water-rich fault tunnels according to claim 3, characterized in that, The initial conditions of the ventilation model for the high geothermal water-rich fault tunnel are as follows: the ventilation volume is 37.10 m 3 / s, the air temperature is 23 °C, and the initial temperature range is 28 °C - 85 °C.

8. The high geothermal water-rich fault tunnel zoning cooling method according to claim 2, characterized in that, The size of the initial model of high geothermal water-rich fault tunnels is 120m × 50m × 50m; the fault width of the initial model of high geothermal water-rich fault tunnels is 20m. Among them, the upper part of the fault is a velocity inlet, adopting the flow velocity of fissure water, and the lower part of the fault is a pressure outlet; the included angle between the initial model of high geothermal water-rich fault tunnels and the horizontal direction is 60°.

9. A partitioned cooling system for a high geothermal water-rich fault tunnel, characterized in that, It includes a ventilation model for high geothermal water-rich fault tunnels and a cooling module, The high geothermal water-rich fault tunnel ventilation model is established with the area X meters away from the tunnel face as the cooling area, which is used to simulate the cooling conditions in the cooling area under different combinations of cooling measures respectively, and obtain the average temperature change curve in the cooling area under different combinations of cooling measures. The cooling module is used to determine the combined cooling scheme according to the average temperature change curve in the cooling area under different combinations of cooling measures, and carry out cooling during the construction of the high geothermal water-rich fault tunnel according to the combined cooling scheme.

10. The high geothermal water-rich fault tunnel zoning cooling system according to claim 9, characterized in that, The different combinations of cooling measures are formed by different combinations of cooling devices, and the different combinations of cooling devices include ventilation cooling devices, ice block cooling devices and spray cooling devices.

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