A high-temperature tunnel prevention and control method and system based on hydration salt cold storage material regulation
By using customized hydrated salt cold storage materials and temperature field prediction models in high-temperature tunnels, combined with modular construction technology, the problems of unstable temperature control and high energy consumption in high-temperature tunnels have been solved, achieving efficient and stable temperature control and improved safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA HYDROELECTRIC ENGINEERING CONSULTING GROUP CHENGDU RESEARCH HYDROELECTRIC INVESTIGATION DESIGN AND INSTITUTE
- Filing Date
- 2026-04-23
- Publication Date
- 2026-06-12
AI Technical Summary
High-temperature tunnels present challenges such as high risk of heatstroke among workers, low labor efficiency, rapid aging of machinery and equipment, and significant risks of thermal stress accumulation and crack propagation in the surrounding rock. Existing prevention and control technologies suffer from high energy consumption, poor temperature control stability, and insufficient material durability.
By adopting a customized hydrated salt cold storage material formula and a numerical temperature field prediction model, combined with modular construction technology, cold storage structures are installed on the tunnel surface and inside the surrounding rock. Long-chain fatty acids are used to regulate the phase change temperature, and temperature sensors are used for real-time monitoring and adjustment to achieve efficient and stable control of tunnel temperature.
It has achieved effective temperature control in high-temperature tunnels, reduced energy consumption, improved temperature control stability and material durability, reduced the risk of thermal stress accumulation in surrounding rock, and ensured tunnel safety and a comfortable working environment.
Smart Images
Figure CN122190812A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of high-temperature tunnel control technology, and more specifically, to a method and system for high-temperature tunnel control based on hydrated salt cold storage materials. Background Technology
[0002] High-temperature tunnels are generally defined as tunnels with an initial surrounding rock temperature of ≥28℃ after excavation. They are a challenging scenario in tunnel engineering. The core issues are: high temperatures increase the risk of heatstroke for workers, reduce labor efficiency, accelerate the aging of mechanical equipment, and increase the frequency of failures; at the same time, high temperatures cause thermal stress to accumulate inside the surrounding rock, which can easily lead to crack expansion, exacerbate rock bursts and softening of soft rock, and threaten tunnel safety.
[0003] Current mainstream prevention and control methods include forced ventilation, cold water circulation cooling, and insulation layer laying, but all have obvious drawbacks: ① Forced ventilation can only reduce the air temperature inside the tunnel, and its effect on areas with large heat dissipation from the surrounding rock is limited; ② Cold water circulation requires continuous power consumption to drive the refrigeration equipment, resulting in high energy costs (the daily energy consumption of a single kilometer of tunnel can reach more than 500 kWh), which is not feasible in actual engineering; ③ Traditional insulation layers (such as polyurethane boards) are easily damaged by deformation of the surrounding rock and cannot actively absorb heat, resulting in poor long-term temperature control stability.
[0004] In phase change energy storage technology, hydrated salt-based cold storage materials have been applied in air conditioning and cold chain transportation due to their advantages such as high latent heat (165-205 kJ / kg), low cost, and non-toxicity and environmental friendliness. However, there are technical limitations in the development of adaptability for high-temperature tunnel scenarios: ① The phase change temperature of conventional hydrated salts (such as sodium sulfate decahydrate) is 32.4℃, which does not match the target temperature control range (20-25℃) of high-temperature tunnels; ② When the phase change temperature is lowered simply by adding inorganic salts (such as ammonium chloride), it is easy to react chemically with nucleating agents (such as borax) to release ammonia, resulting in an increased material cold storage decay rate (more than 30% decay after 250 cycles), which cannot meet the long-term operation requirements of tunnels; ③ In existing technologies, phase change temperature regulators mostly rely on polyols, and excessive use of polyols will significantly reduce the heat storage effect of cold storage materials, and there is a lack of adaptability optimization for the humid and vibrating environment of tunnels; ④ There is a lack of design for the encapsulation and construction process of cold storage materials for the complex geological environment of tunnels, resulting in a high risk of material leakage or stability failure.
[0005] Therefore, this application is hereby submitted. Summary of the Invention
[0006] The purpose of this invention is to provide a method and system for controlling high-temperature tunnels based on hydrated salt cold storage materials. It addresses the problems of high energy consumption, poor temperature control stability, insufficient material durability, and limited cooling effect in existing high-temperature tunnel control technologies. By customizing cold storage material formulations, numerical temperature field prediction, and modular construction processes, it achieves efficient and stable control of tunnel temperature.
[0007] The above-mentioned technical objective of the present invention is achieved through the following technical solution:
[0008] In a first aspect, this application provides a method for controlling high-temperature tunnels based on hydrated salt cold storage materials, comprising the following steps:
[0009] After the tunnel is excavated, shotcrete and anchor bolts are used for initial support. After curing, the support surface is ground to a smooth surface and dust and water are removed.
[0010] Temperature sensors are placed on the surface of the initial support and continuously monitored for a first preset time. The acquired initial temperature distribution data of the tunnel is used to calibrate the model parameters of the constructed temperature field prediction model.
[0011] The radial temperature field distribution data of the tunnel at each time moment is output using the temperature field prediction model after model parameter calibration, and the installation of the cold storage structure is carried out based on the temperature field distribution data.
[0012] After the cold storage structure is installed, it undergoes a second preset trial run, and the temperature change curve is formed by the temperature data obtained by the temperature sensor during the trial run.
[0013] If the temperature change curve does not meet the preset conditions, increase the number of cold storage structures or adjust the ventilation volume until the temperature change curve meets the preset conditions.
[0014] Based on the above technical solution, the present invention can be further improved as follows.
[0015] Furthermore, the above temperature field prediction model is based on a three-layer concentric cylindrical structure consisting of an air layer, a composite lining layer, and a surrounding rock layer. The temperature field prediction model includes nodal equations for the non-phase change heat control layer and nodal equations for the phase change heat control layer.
[0016] Furthermore, the specific nodal equations for the non-phase change heat control layer are as follows: ; In the formula, The density of the medium, Indicates the specific heat capacity of the medium. The volume of the node control volume. This represents the temperature of node i at time k. For time step, Indicates the thermal conductivity of the medium. Let be the heat transfer area of node i. Indicates the spatial step size.
[0017] Furthermore, the specific nodal equations for the aforementioned phase change heat control layer are as follows: ; In the formula, The density of the cold storage layer in the composite lining is... This indicates the specific heat capacity of the cold storage layer in the composite lining. The volume of the node control volume. This represents the temperature of node i at time k. For time step, This represents the latent heat of phase change of the cold storage layer in the composite lining. Let be the phase transition mass of node i at time k. This represents the thermal conductivity of the cold storage layer in the composite lining. For spatial step size, This represents the heat transfer area of node i.
[0018] Furthermore, the aforementioned cold storage structure includes a cold storage plate, a cold storage pipe, and a cold storage material filled inside the cold storage plate and the cold storage pipe.
[0019] Furthermore, the aforementioned cold storage materials include inorganic hydrates, water-soluble salts, long-chain fatty acids, nucleating agents, and thickeners.
[0020] Furthermore, the aforementioned inorganic salt hydrate is anhydrous sodium sulfate, with a mass percentage of not less than 55%; the water-soluble salt is sodium chloride, with a mass percentage of 12%-38%; the long-chain fatty acid is palmitic acid, with a mass percentage of 15%-45%; the nucleating agent is sodium borate decahydrate, with a mass percentage of 1%-10%; and the thickener is polyanionic cellulose, with a mass percentage of 3%-10%.
[0021] Furthermore, the aforementioned cold storage material is obtained through the following methods:
[0022] Weigh anhydrous sodium sulfate, sodium chloride, sodium borate decahydrate, and polyanionic cellulose according to the formula, place them in a stirred kettle with a jacket to be heated, and dry mix at room temperature for 5-10 minutes.
[0023] Add the predetermined mass of water to the stirred tank, heat to 30-35℃, stir for 15-20 minutes until the solid is completely dissolved to form a homogeneous solution;
[0024] Heat palmitic acid separately until completely melted, then slowly add the molten palmitic acid to the above solution, maintaining the temperature of the stirred tank at 35-40℃ and stirring continuously for 15-20 minutes;
[0025] Pour the mixture into the cold storage structure, seal it, and place it in an environment of 5-20℃ for several solidification and melting cycles. Each cycle should have a solidification time of no less than 8 hours and a melting time of no less than 4 hours.
[0026] The phase change temperature and cold storage capacity of the cold storage material in the cold storage structure were tested using the T-history method until the cold storage decay rate of the cold storage material after cycling did not exceed the threshold.
[0027] Furthermore, the installation of the cold storage structure based on the temperature field distribution data is specifically as follows:
[0028] If the surface temperature of the initial support in the temperature field distribution data is not lower than 28℃, the cold storage plate is fixed on the surface of the initial support with expansion bolts, and the outer wall of the cold storage plate is made to fit with the surface of the initial support, and the gap between adjacent cold storage plates is filled with low-temperature resistant sealant.
[0029] If the internal temperature of the surrounding rock in the temperature field distribution data is not lower than 40℃, use a geological drilling rig to drill holes in the surrounding rock with a diameter of 60-90mm, a depth of 1-1.5m, and a hole spacing of 0.5-0.8m. The drilling direction should be consistent with the direction of the principal stress of the surrounding rock. Wrap the outer wall of the cold storage pipe with insulation cotton, exposing the heat dissipation hole area of the cold storage pipe. Insert the cold storage pipe into the drill hole, and fill and fix the gap between the cold storage pipe and the inner wall of the drill hole with cement mortar.
[0030] Secondly, this application provides a high-temperature tunnel control system based on hydrated salt cold storage materials, applied to any one of the high-temperature tunnel control methods based on hydrated salt cold storage materials in the first aspect, including:
[0031] The temperature monitoring module uses distributed fiber optic temperature sensors deployed in the tunnel's arch, waist, and sidewalls. It acquires temperature data in real time through each sensor and generates initial temperature distribution data and temperature change curves for the tunnel based on this data.
[0032] The temperature field prediction model is based on the initial temperature distribution data of the tunnel. The model parameters are calibrated, and the radial temperature field distribution data of the tunnel at each time point is output after the model parameters are calibrated.
[0033] A cold storage structure includes a cold storage plate, a cold storage pipe, and a cold storage material filled inside the cold storage plate and the cold storage pipe.
[0034] Compared with the prior art, the present invention has at least the following beneficial effects:
[0035] In this application, long-chain fatty acids, which are widely available, non-toxic, and chemically stable, are used as phase transition temperature regulators. Long-chain fatty acids are non-paraffinic organic materials, and their molecular structure can reduce the water activity of hydrated salts and thus lower the eutectic point of hydrated salts through synergistic effects with water-soluble salts. The core principle is to reduce the water activity in order to synergistically regulate the phase transition temperature of hydrated salts, which is suitable for the needs of high geothermal tunnel control. In view of the problems of high energy consumption, poor temperature control stability, insufficient material durability, and limited cooling effect of existing high geothermal tunnel control technologies, efficient and stable control of tunnel temperature is achieved through customized cold storage material formulations, numerical temperature field prediction, and modular construction processes. Attached Figure Description
[0036] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:
[0037] Figure 1 This is a flowchart of the prevention and control method in an embodiment of the present invention;
[0038] Figure 2 This is a flowchart of the method for obtaining cold storage materials in an embodiment of the present invention;
[0039] Figure 3 This is a schematic diagram of the installation of the cold storage structure in an embodiment of the present invention.
[0040] The attached diagram shows the markings and corresponding component names:
[0041] 1. High-temperature surrounding rock; 2. Initial support; 3. Temperature sensor; 4. Cold storage pipe; 5. Cold storage plate; 6. Secondary lining. Detailed Implementation
[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0043] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0044] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0045] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, they are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.
[0046] Furthermore, the use of terms such as "horizontal," "vertical," and "sag" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.
[0047] In the description of the embodiments of the present invention, "multiple" means at least two.
[0048] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.
[0049] Example 1: Addressing the problems existing in current cooling methods for high-temperature tunnels, this example provides a high-temperature tunnel control method based on hydrated salt cold storage materials, such as... Figure 1 As shown, the specific steps include the following:
[0050] S1 uses shotcrete and anchor bolts for initial support after tunnel excavation. After curing, the support surface is ground smooth and dust and water are removed to lay the foundation for the installation of the cooling storage structure.
[0051] S2, Temperature sensors 3 are installed on the surface of the initial support and continuously monitored for a first preset time. The acquired initial temperature distribution data of the tunnel is used to calibrate the parameters of the constructed temperature field prediction model. Temperature monitoring can be performed using distributed fiber optic temperature sensors 3 installed at the tunnel arch, arch waist, and sidewalls. (See [reference]) Figure 3The data acquisition unit and remote monitoring platform transmit temperature data to the temperature field prediction model in real time and dynamically output the radial temperature field distribution data of the tunnel at each moment.
[0052] The tunnel system can be simplified into a two-dimensional axisymmetric model. Based on the circular coupling model of "air-lining-surrounding rock", the temperature control equations of the nodes are derived through spatiotemporal discretization, and the temperature field distribution prediction data of the entire life cycle of the tunnel is output. Specifically, the above temperature field prediction model is based on a three-layer concentric cylindrical structure of air layer, composite lining layer and surrounding rock layer. The temperature field prediction model includes the node equations of non-phase change heat control layer and phase change heat control layer.
[0053] Optionally, the above-mentioned nodal equations for the non-phase change heat-controlling layer are as follows: ; In the formula, The density of the medium, Indicates the specific heat capacity of the medium. The volume of the node control volume. This represents the temperature of node i at time k. For time step, Indicates the thermal conductivity of the medium. Let be the heat transfer area of node i. Indicates the spatial step size.
[0054] Optionally, the above phase change heat control layer nodal equations are as follows: ; In the formula, The density of the cold storage layer in the composite lining is... This indicates the specific heat capacity of the cold storage layer in the composite lining. The volume of the node control volume. This represents the temperature of node i at time k. For time step, This represents the latent heat of phase change of the cold storage layer in the composite lining. Let be the phase transition mass of node i at time k. This represents the thermal conductivity of the cold storage layer in the composite lining. For spatial step size, This represents the heat transfer area of node i.
[0055] Among them, in the above-mentioned nodal equations of non-phase change heat control layer and nodal equations of phase change heat control layer, the nodal equations can be solved by Gaussian elimination method, which can output the radial temperature field distribution of the tunnel at each time, and the prediction period covers the tunnel construction period to the initial operation period.
[0056] S3 uses the temperature field prediction model after model parameter calibration to output the radial temperature field distribution data of the tunnel at each time moment, and installs the cold storage structure based on the temperature field distribution data.
[0057] The cold storage structure can be installed in two ways, such as Figure 3 As shown, the selection is based on the temperature field prediction results:
[0058] 1. Surface laying (applicable to areas with support surface temperature ≥28℃): Mark the installation position of the cold storage plate 5 on the surface of the initial support 2, and fix the cold storage plate 5 with expansion bolts to ensure that the plate is in close contact with the support surface; fill the gaps between the plates with low temperature resistant sealant to prevent cold leakage and water vapor intrusion.
[0059] 2. High-temperature surrounding rock 1 burial (applicable to areas where the internal temperature of high-temperature surrounding rock 1 is ≥40℃): Use a geological drilling rig to drill holes in the high-temperature surrounding rock 1 with a diameter of 60-90mm, a depth of 1-1.5m, and a hole spacing of 0.5-0.8m. The drilling direction should be consistent with the principal stress direction of the high-temperature surrounding rock 1 to avoid inducing cracks; wrap the outer wall of the cold storage pipe 4 with insulation cotton, leaving only the heat dissipation hole area exposed, insert the cold storage pipe 4 into the drill hole, and fill the gap with cement mortar to fix it.
[0060] The aforementioned cold storage structure includes a cold storage plate 5, a cold storage pipe 4, and a cold storage material filled inside the cold storage plate 5 and the cold storage pipe 4. The cold storage plate 5 can be 1000mm×500mm×100mm in size, with pre-drilled bolt holes on its surface for laying on the surface of the initial support 2. The diameter of the cold storage pipe 4 can be 50-80mm, and its length can be 2-3m. Heat dissipation holes are opened in the pipe wall for drilling and embedding in the high-temperature surrounding rock 1. The cold storage plate 5 and the cold storage pipe 4 can be made of high-temperature resistant polyethylene.
[0061] The aforementioned cold storage material can be composed of inorganic hydrate, water-soluble salt, long-chain fatty acid, nucleating agent, and thickener. The long-chain fatty acid is solid at room temperature; after heating and melting, it can synergistically reduce the water activity of the hydrated salt with the water-soluble salt, thereby significantly altering the phase transition temperature. Furthermore, it exhibits excellent chemical stability and will not react with the nucleating agent. The inorganic hydrate is anhydrous sodium sulfate, with a mass percentage of not less than 55%. The water-soluble salt is sodium chloride, with a mass percentage of 12%-38%. The long-chain fatty acid is palmitic acid, with a mass percentage of 15%-45%. The nucleating agent is sodium borate decahydrate, with a mass percentage of 1%-10%. The thickener is polyanionic cellulose, with a mass percentage of 3%-10%.
[0062] Optionally, the cold storage material can be obtained through the following methods, such as... Figure 2 As shown:
[0063] S31. Weigh anhydrous sodium sulfate, sodium chloride, sodium borate decahydrate, and polyanionic cellulose according to the formula, place them in a stirred kettle with a jacket to be heated, and dry mix at room temperature for 5-10 minutes.
[0064] S32, add the preset mass of water to the stirred tank, heat to 30-35℃, stir for 15-20 minutes until the solid is completely dissolved to form a homogeneous solution.
[0065] S33, heat palmitic acid separately until completely melted, slowly add the molten palmitic acid to the above solution, maintain the temperature of the stirred tank at 35-40℃ and continue stirring for 15-20 minutes.
[0066] S34. Pour the mixture into the cold storage structure, seal it, and place it in an environment of 5-20℃ for several solidification and melting cycles. Each cycle should have a solidification time of no less than 8 hours and a melting time of no less than 4 hours.
[0067] S35, the phase change temperature and cold storage capacity of the cold storage material in the cold storage structure are tested using the T-history method until the cold storage decay rate of the cold storage material does not exceed the threshold after cycling.
[0068] S4, after the cold storage structure is installed, undergoes a second preset trial run, and the temperature change curve is formed by the temperature data obtained by the temperature sensor during the trial run.
[0069] S5. If the temperature change curve does not meet the preset conditions, increase the number of cold storage structures or adjust the ventilation volume until the formed temperature change curve meets the preset conditions.
[0070] The process involves obtaining real-time temperature data via temperature sensors, setting a temperature control threshold (maximum temperature inside the tunnel ≤ 25℃), conducting continuous trial operation for 72 hours, and recording the temperature change curve. If the temperature in the high-temperature zone drops to 22-25℃ and the fluctuation range is ≤ ±1℃, the commissioning is deemed successful. If the temperature does not meet the standard, the number of cold storage structures is increased or the ventilation volume is adjusted.
[0071] Specifically, the secondary lining reinforcement is tied according to the design, and the distance between the reinforcement and the cold storage structure is kept at ≥50mm to avoid the reinforcement colliding with the module during construction; for the area of the cold storage pipe buried in the surrounding rock, a clearance hole with a diameter of 100-150mm is reserved in the secondary lining reinforcement mesh, the center of the hole is aligned with the axis of the cold storage pipe, and an 8mm diameter reinforcing stirrup is added around the hole.
[0072] During later use, the T-history method is used to sample and test the cold storage attenuation rate every six months. When the attenuation rate is greater than 10%, the cold storage structure is replaced. At the same time, the temperature field prediction model is calibrated, and the operating parameters of the auxiliary heat dissipation module are adjusted in combination with the tunnel operation load to ensure long-term temperature control effect.
[0073] Example 2: This application provides a high-temperature tunnel control system based on hydrated salt cold storage materials, applied to the high-temperature tunnel control method based on hydrated salt cold storage materials in Example 1, including:
[0074] The temperature monitoring module uses distributed fiber optic temperature sensors deployed in the tunnel's arch, waist, and sidewalls. It acquires temperature data in real time through each sensor and generates initial temperature distribution data and temperature change curves for the tunnel based on this data.
[0075] The temperature field prediction model is based on the initial temperature distribution data of the tunnel, and the model parameters are calibrated. After calibration, the radial temperature field distribution data of the tunnel at each time point is output. The temperature field prediction model is based on a three-layer concentric cylindrical structure consisting of an air layer, a composite lining layer, and a surrounding rock layer. The temperature field prediction model includes nodal equations for the non-phase change heat-controlling layer and nodal equations for the phase change heat-controlling layer. Specifically, the nodal equations for the non-phase change heat-controlling layer are as follows: ; In the formula, For the density of the medium, Indicates the specific heat capacity of the medium. The volume of the node control volume. This represents the temperature of node i at time k. For time step, Indicates the thermal conductivity of the medium. Let be the heat transfer area of node i. Indicates the spatial step size.
[0076] The specific nodal equations for the phase change heat control layer mentioned above are as follows: ; In the formula, The density of the cold storage layer in the composite lining is... This indicates the specific heat capacity of the cold storage layer in the composite lining. The volume of the node control volume. This represents the temperature of node i at time k. For time step, This represents the latent heat of phase change of the cold storage layer in the composite lining. Let be the phase transition mass of node i at time k. This represents the thermal conductivity of the cold storage layer in the composite lining. For spatial step size, This represents the heat transfer area of node i.
[0077] The cold storage structure includes a cold storage plate, a cold storage pipe, and a cold storage material filled inside the cold storage plate and the cold storage pipe; the cold storage material includes inorganic salt hydrates, water-soluble salts, long-chain fatty acids, nucleating agents, and thickeners.
[0078] The inorganic salt hydrate is anhydrous sodium sulfate, with a mass percentage of not less than 55%; the water-soluble salt is sodium chloride, with a mass percentage of 12%-38%; the long-chain fatty acid is palmitic acid, with a mass percentage of 15%-45%; the nucleating agent is sodium borate decahydrate, with a mass percentage of 1%-10%; and the thickener is polyanionic cellulose, with a mass percentage of 3%-10%.
[0079] See Figure 2 The aforementioned cold storage material is obtained through the following methods:
[0080] S31. Weigh anhydrous sodium sulfate, sodium chloride, sodium borate decahydrate, and polyanionic cellulose according to the formula, place them in a stirred kettle with a jacket to be heated, and dry mix at room temperature for 5-10 minutes.
[0081] S32, add the preset mass of water to the stirred tank, heat to 30-35℃, stir for 15-20 minutes until the solid is completely dissolved to form a homogeneous solution.
[0082] S33, heat palmitic acid separately until completely melted, slowly add the molten palmitic acid to the above solution, maintain the temperature of the stirred tank at 35-40℃ and continue stirring for 15-20 minutes.
[0083] S34. Pour the mixture into the cold storage structure, seal it, and place it in an environment of 5-20℃ for several solidification and melting cycles. Each cycle should have a solidification time of no less than 8 hours and a melting time of no less than 4 hours.
[0084] S35, the phase change temperature and cold storage capacity of the cold storage material in the cold storage structure are tested using the T-history method until the cold storage decay rate of the cold storage material does not exceed the threshold after cycling.
[0085] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for controlling high-temperature tunnels based on hydrated salt cold storage materials, characterized in that, Includes the following steps: After the tunnel is excavated, shotcrete and anchor bolts are used for initial support. After curing, the support surface is ground to a smooth surface and dust and water are removed. Temperature sensors are placed on the surface of the initial support and continuously monitored for a first preset time. The acquired initial temperature distribution data of the tunnel is used to calibrate the model parameters of the constructed temperature field prediction model. The radial temperature field distribution data of the tunnel at each time moment is output using the temperature field prediction model after model parameter calibration, and the installation of the cold storage structure is carried out based on the temperature field distribution data. After the cold storage structure is installed, it undergoes a second preset trial run, and the temperature change curve is formed by the temperature data obtained by the temperature sensor during the trial run. If the temperature change curve does not meet the preset conditions, the number of cold storage structures is increased or the ventilation volume is adjusted until the temperature change curve meets the preset conditions.
2. The method for controlling high-temperature tunnels based on hydrated salt cold storage materials according to claim 1, characterized in that, The temperature field prediction model is based on a three-layer concentric cylindrical structure consisting of an air layer, a composite lining layer, and a surrounding rock layer. The temperature field prediction model includes nodal equations for the non-phase change heat control layer and nodal equations for the phase change heat control layer.
3. The method for controlling high-temperature tunnels based on hydrated salt cold storage materials according to claim 2, characterized in that, The specific nodal equations for the non-phase change heat control layer are as follows: ； In the formula, For the density of the medium, Indicates the specific heat capacity of the medium. The volume of the node control volume. This represents the temperature of node i at time k. For time step, Indicates the thermal conductivity of the medium. Let be the heat transfer area of node i. Indicates the spatial step size.
4. The method for controlling high-temperature tunnels based on hydrated salt cold storage materials according to claim 2, characterized in that, The specific nodal equations for the phase change heat control layer are as follows: ； In the formula, The density of the cold storage layer in the composite lining is... This indicates the specific heat capacity of the cold storage layer in the composite lining. The volume of the node control volume. This represents the temperature of node i at time k. For time step, This represents the latent heat of phase change of the cold storage layer in the composite lining. Let be the phase transition mass of node i at time k. This represents the thermal conductivity of the cold storage layer in the composite lining. For spatial step size, This represents the heat transfer area of node i.
5. A method for controlling high-temperature tunnels based on hydrated salt cold storage materials according to claim 1, characterized in that, The cold storage structure includes a cold storage plate, a cold storage pipe, and a cold storage material filled inside the cold storage plate and the cold storage pipe.
6. A method for controlling high-temperature tunnels based on hydrated salt cold storage materials according to claim 5, characterized in that, The cold storage material includes inorganic hydrates, water-soluble salts, long-chain fatty acids, nucleating agents, and thickeners.
7. A method for controlling high-temperature tunnels based on hydrated salt cold storage materials according to claim 6, characterized in that, The inorganic salt hydrate is anhydrous sodium sulfate, with a mass percentage of not less than 55%; the water-soluble salt is sodium chloride, with a mass percentage of 12%-38%; the long-chain fatty acid is palmitic acid, with a mass percentage of 15%-45%; the nucleating agent is sodium borate decahydrate, with a mass percentage of 1%-10%; and the thickener is polyanionic cellulose, with a mass percentage of 3%-10%.
8. A method for controlling high-temperature tunnels based on hydrated salt cold storage materials according to claim 6, characterized in that, The cold storage material is obtained through the following methods: Weigh anhydrous sodium sulfate, sodium chloride, sodium borate decahydrate, and polyanionic cellulose according to the formula, place them in a stirred kettle with a jacket to be heated, and dry mix at room temperature for 5-10 minutes. Add the predetermined mass of water to the stirred tank, heat to 30-35℃, stir for 15-20 minutes until the solid is completely dissolved to form a homogeneous solution; Heat palmitic acid separately until completely melted, then slowly add the molten palmitic acid to the above solution, maintaining the temperature of the stirred tank at 35-40℃ and stirring continuously for 15-20 minutes; Pour the mixture into the cold storage structure, seal it, and place it in an environment of 5-20℃ for several solidification and melting cycles. Each cycle should have a solidification time of no less than 8 hours and a melting time of no less than 4 hours. The phase change temperature and cold storage capacity of the cold storage material in the cold storage structure were tested using the T-history method until the cold storage decay rate of the cold storage material after cycling did not exceed the threshold.
9. A method for controlling high-temperature tunnels based on hydrated salt cold storage materials according to claim 5, characterized in that, The installation of the cold storage structure is based on temperature field distribution data, specifically as follows: If the surface temperature of the initial support in the temperature field distribution data is not lower than 28℃, the cold storage plate is fixed on the surface of the initial support with expansion bolts, and the outer wall of the cold storage plate is made to fit with the surface of the initial support, and the gap between adjacent cold storage plates is filled with low-temperature resistant sealant. If the internal temperature of the surrounding rock in the temperature field distribution data is not lower than 40℃, use a geological drilling rig to drill holes in the surrounding rock with a diameter of 60-90mm, a depth of 1-1.5m, and a hole spacing of 0.5-0.8m. The drilling direction should be consistent with the direction of the principal stress of the surrounding rock. Wrap the outer wall of the cold storage pipe with insulation cotton, exposing the heat dissipation hole area of the cold storage pipe. Insert the cold storage pipe into the drill hole, and fill and fix the gap between the cold storage pipe and the inner wall of the drill hole with cement mortar.
10. A high-temperature tunnel control system based on hydrated salt cold storage materials, characterized in that, include: The temperature monitoring module uses distributed fiber optic temperature sensors deployed on the tunnel's arch, waist, and sidewalls. It acquires temperature data in real time through each deployed temperature sensor and generates initial temperature distribution data and temperature change curves for the tunnel based on the temperature data. The temperature field prediction model is based on the initial temperature distribution data of the tunnel. The model parameters are calibrated, and the radial temperature field distribution data of the tunnel at each time point is output after the model parameters are calibrated. A cold storage structure, comprising a cold storage plate, a cold storage pipe, and a cold storage material filled inside the cold storage plate and the cold storage pipe.