Construction method of secondary lining concrete heat insulation layer of hole section in alpine region

Abstract

The application discloses a construction method of a secondary lining concrete heat insulation layer of a cave section in an alpine region, relates to the technical field of civil engineering in cold regions, and comprises the following steps of S1, dust and dirt on the surface of the secondary lining is cleaned; S2, a U-shaped component is installed; S3, the airfoil plate of the U-shaped component is used to fix the electric heating plate, and then a heat insulation plate is installed; S4, an air channel is formed in the heat insulation layer, a monitoring assembly is installed in the air channel, and then a temperature acquisition assembly and a control assembly are installed inside the cave; the monitoring assembly is used to collect the gas flow direction inside the air channel; the control assembly is used to judge the position where the temperature difference appears in the heat insulation layer according to the gas flow scheme, control the temperature acquisition assembly to collect the temperature of the position where the temperature difference appears, acquire a group of temperature information, select the maximum value in the group of temperature information as a standard value, and then control the electric heating plate to work according to the temperature information until the temperature information of the position where the temperature difference appears reaches the standard value, so that the automatic heating of the secondary lining is realized.

Description

Technical Field

[0001] This invention relates to the field of civil engineering technology in cold regions, and in particular to a construction method for a secondary lining concrete thermal insulation layer in the entrance section of a tunnel in high-altitude and cold regions. Background Technology

[0002] Tunnel entrance sections in high-altitude and frigid regions face severe challenges such as extreme low temperatures (annual average temperature -10℃ to -30℃), intense freeze-thaw cycles (50 to 100 cycles per year), and frost heave stress (up to 2 to 5 MPa). As the core load-bearing layer of the tunnel structure, the secondary lining at the entrance section must achieve the following objectives through a thermal insulation layer: Prevent concrete frost damage: Avoid the freezing and expansion of internal moisture in the concrete due to low temperatures, which can lead to cracking (frost heave stress can cause crack width > 0.3 mm); Inhibit freeze-thaw cycle damage: Reduce material fatigue degradation caused by temperature fluctuations (concrete strength loss can reach 30% to 50% after 100 freeze-thaw cycles); Maintain structural thermal stability: Control the temperature difference between the inside and outside of the lining (usually ≤ 15℃) to prevent thermal stress cracks (for every 10℃ increase in temperature difference, thermal stress increases by approximately 2 MPa).

[0003] In existing technologies, two main types of insulation are passive and active insulation. Active insulation includes electric heat tracing systems: carbon fiber heating cables (15~25W / m) are pre-embedded in the lining, and a temperature controller maintains the lining surface temperature above 0℃. Geothermal utilization: geothermal pipes are embedded to circulate antifreeze (ethylene glycol solution), utilizing the ground temperature (5~10℃) to transfer heat.

[0004] However, due to the characteristics of high-altitude and cold regions with high radiation and abundant sunshine, there is a temperature difference between the area at the tunnel entrance that receives sunshine and the area that does not receive sunshine. Continuous active insulation can easily lead to energy waste. On the other hand, the scheme of heating after uniform temperature measurement can easily overlook the lower temperature areas, thereby triggering freeze-thaw cycles in those areas and affecting the stability of the structure. Summary of the Invention

[0005] The purpose of this invention is to provide a construction method for secondary lining concrete thermal insulation layer in tunnel entrance sections in high-altitude and cold regions, so as to solve the above-mentioned problems.

[0006] This invention is achieved through the following technical solution:

[0007] A construction method for a secondary lining concrete thermal insulation layer in tunnel entrance sections in high-altitude and cold regions includes:

[0008] S1: Select insulation boards, keel, fiber reinforced device boards and several electric heating plates, then clean the surface of the secondary lining and repair the defective parts of the secondary lining surface.

[0009] S2: Select several U-shaped components, measure and lay out the lines on the secondary lining surface, and install the U-shaped components;

[0010] S3: The heating plate is fixed by the wing plate of the U-shaped component, then the insulation board is installed, and the insulation board is pressed so that the wing plate of the U-shaped component enters the insulation board:

[0011] S4: An air passage is opened in the insulation layer, and a monitoring component is installed in the air passage. Then, a temperature acquisition component and a control component are installed inside the opening. The monitoring component, the temperature acquisition component, and the heating plate are all electrically connected to the control component.

[0012] The monitoring component is used to collect the direction of gas flow inside the airway. The control component determines the location of the temperature difference in the insulation layer according to the gas flow pattern, and controls the temperature acquisition component to collect the temperature at the location of the temperature difference, obtain a set of temperature information, select the maximum value in the set of temperature information as the standard value, and then control the heating plate to work according to the temperature information until the temperature information at the location of the temperature difference reaches the standard value.

[0013] S5: Fix the keel with the U-shaped component, and use self-tapping screws to install the fiber-reinforced device plate on the side of the keel away from the insulation board. Then fill the joint to complete the construction of the secondary lining concrete thermal insulation layer of the tunnel entrance section in the high-altitude and cold region.

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0015] 1. The design of the insulation board and U-shaped component in this invention, compared with the prior art, eliminates the need for cutting and segmenting the insulation board during construction, thereby greatly reducing the number of joints in the insulation board, making installation convenient and quick. This reduces the number of steps required for operators while also improving the insulation effect of the structure.

[0016] 2. The design of the electric heating plate in this invention uses the electric heating plate to heat the secondary lining, ensuring that the surface temperature of the secondary lining is at a suitable temperature, realizing active heat preservation, improving the stability of the post-construction structure, and avoiding the impact of freeze-thaw cycles on the structure.

[0017] 3. The design of the monitoring component, temperature acquisition component and control component in this invention, through the coordinated work with the heating plate, roughly determines the location of temperature difference change based on the airflow direction in the air passage inside the insulation layer. Then, the control component controls the temperature acquisition component to only acquire temperature at the location of temperature difference change, and controls the heating plate at the corresponding location to work based on the acquisition results.

[0018] Compared to existing technologies, this solution uses monitoring components to initially screen locations where temperature changes occur on the secondary lining surface. The temperature acquisition components only operate at these locations, which helps to rapidly expand the data acquisition range while reducing the energy consumption of various structures in the insulation layer after construction, thus extending the lifespan of the insulation layer. Furthermore, compared to solutions that simultaneously heat the secondary lining surface, this solution monitors the temperature at various locations within the secondary lining to achieve automated, differentiated heating. This helps avoid continuously heating high-temperature areas or ignoring low-temperature areas, thereby reducing the occurrence of freeze-thaw cycles in various locations of the secondary lining and extending the lifespan of both the secondary lining and the insulation layer.

[0019] Furthermore, in S1, a photovoltaic solar power generation module is selected. Based on the geographical conditions of the cave entrance, the photovoltaic solar power generation module is installed at the location with the longest sunshine duration. The photovoltaic solar power generation module is used to supply power to the electric heating plate, the monitoring module, the temperature acquisition module, and the control module.

[0020] Beneficial effects: Compared with existing technologies, this solution uses photovoltaic solar power generation modules, which makes full use of the characteristics of strong radiation and abundant sunshine in high-altitude and cold regions, and uses clean energy to generate electricity, saving energy consumption.

[0021] Furthermore, the monitoring component in S4 includes a conductive rod and several batteries. The conductive rod is made of metal, and an insulating cover is fitted onto any end of the conductive rod. The insulating cover is fixedly connected to the side wall of the airway, and several conductive strips are fixedly connected to the insulating cover. The number of batteries electrically connected to each conductive strip is different. A current sensor is electrically connected to the conductive rod. The current sensor is used to collect current information passing through the conductive rod. The conductive strips are used to connect the circuit of the current sensor and the batteries. The control component determines the position of the conductive strip electrically connected to the conductive rod based on the current information, and obtains the gas flow direction in the airway based on the position of the conductive strip.

[0022] Beneficial effects: Compared with existing technologies, the solution of using conductive rods and conductive strips with current sensors has the sensors located on the outside, which facilitates post-work inspection and maintenance, reduces later maintenance costs and steps, and the sensors in this solution are less affected by temperature, which helps to improve the accuracy of the data collected by the monitoring components.

[0023] Furthermore, the temperature acquisition component includes an infrared temperature sensor and a multi-axis motion platform. The infrared sensor is fixedly connected to the multi-axis motion platform, and the multi-axis fixed platform is installed inside the port.

[0024] Beneficial effects: Compared with existing technologies, the collaborative work of infrared temperature sensors and multi-axis motion platforms enables the collection of temperature data at various locations of the secondary lining using a single sensor, reducing the investment cost of sensors during the implementation of the solution. Furthermore, since the sensors in this solution are located outside the structure, the cost and steps of subsequent maintenance are further reduced.

[0025] Furthermore, in S2, the U-shaped components are arranged in a matrix.

[0026] Beneficial effects: Compared with existing technologies, this solution avoids uneven distribution of tensile force applied to the insulation layer and other structures through the matrix arrangement of U-shaped components, thus preventing stress concentration. At the same time, the matrix arrangement of U-shaped components also makes the size of the heating plates arranged in them uniform, which is helpful for the preparation, transportation and storage of the heating plates.

[0027] Furthermore, the steps for installing the insulation board in S3 include:

[0028] S3-1: Cut the insulation board according to the second lining dimensions;

[0029] S3-2: Press the insulation board to embed the wing plate of the U-shaped component into the insulation board, and continue to push the insulation board so that the side of the insulation board close to the heating plate is in contact with the heating plate.

[0030] Beneficial effects: Compared with existing technologies, the installation steps of the insulation board in this solution reduce the gap between the heating plate and the insulation board, avoiding the formation of a large cavity between them, which would create a local thermal bridge effect and affect the overall insulation effect. At the same time, it can also reduce the risk of condensation between the two and reduce the risk of them separating after construction.

[0031] Furthermore, the steps for installing the keel in the S5 include:

[0032] S5-1: Orient the opening of the keel toward the insulation board and press the keel so that the U-shaped component passes through the keel and the keel is embedded in the insulation board;

[0033] S5-2: Bend the wing plates of the U-shaped component toward each other, so that the wing plates of the U-shaped component cross and fasten to the keel, thus completing the installation of the keel.

[0034] Beneficial effects: Compared with existing technologies, this solution uses U-shaped components to fix the keel, which eliminates the need for complex welding, is easy to operate, flexible in adjustment, and has significant mechanical advantages.

[0035] Furthermore, after the joints in S5 are filled, a vacuum pump is used to create negative pressure inside the thermal insulation layer, and the change in air pressure inside the thermal insulation layer is continuously monitored. Only when the difference in air pressure change within a set time is less than a preset value, the air pressure in the thermal insulation layer is brought back to atmospheric pressure by the vacuum pump.

[0036] Beneficial Effects: Compared to existing technologies, this solution, after the insulation layer is constructed, creates negative pressure inside and monitors the pressure changes within the insulation layer to determine its airtightness, thus improving the final quality of the completed insulation layer. If the pressure difference within a set time is less than a preset value, the insulation layer meets the airtightness standard, and the internal pressure is subsequently restored to atmospheric pressure to prevent damage to the insulation structure from negative pressure. If the pressure difference within a set time is greater than or equal to the preset value, the airtightness of the insulation layer does not meet the standard. Operators can then use methods such as marked gas monitoring to locate leaks and determine whether rework or repair is necessary based on the size and location of the leaks.

[0037] Furthermore, the insulation board described in S1 is made of polyphenolic foam material, and its thickness is not less than fifty millimeters.

[0038] Beneficial effects: Compared with other solutions, this solution utilizes the properties of polyphenolic foam material to avoid thermal convection between the gas inside the airway and the external gas, which would affect the accuracy of data acquisition by the monitoring components.

[0039] Furthermore, the photovoltaic solar power generation module includes photovoltaic cells, solar panels, and an inverter. The temperature acquisition module is also used to collect the temperature of the solar panels. The control module determines the current sunshine conditions based on the temperature of the solar panels and controls the operation of the electric heating plate based on the current sunshine conditions.

[0040] Beneficial effects: Compared with existing technologies, this solution uses a temperature acquisition component to collect the temperature of the solar panel, thereby determining the real-time sunshine status. This avoids heating the secondary lining during periods of strong sunshine, which could cause the structure to overheat and affect its stability. Attached Figure Description

[0041] 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:

[0042] Figure 1 This is a flowchart of the present invention;

[0043] Figure 2 This is a plan view of the heating plate installation in this invention;

[0044] Figure 3 This is an elevation view of the insulation layer in this invention;

[0045] Figure 4 This is an elevation view of the U-shaped component in this invention;

[0046] Figure 5 This is a cross-sectional view of the insulation layer in this invention;

[0047] Figure 6 This is a schematic diagram of the conductive rod portion in the monitoring component of Embodiment 2 of the present invention.

[0048] The reference numerals in the attached drawings represent: 1. secondary lining; 2. U-shaped component; 21. expansion bolt; 3. heating plate; 4. insulation board; 5. keel; 6. self-tapping screw; 7. fiber reinforced device board; 8. monitoring component; 81. conductive rod; 82. insulating cover; 83. conductive strip. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for illustrative purposes only and are not intended to limit the invention. It should be noted that this invention is already in the actual research and development stage.

[0050] Example 1

[0051] like Figures 1 to 5 As shown, this embodiment includes

[0052] S1: Select insulation board 4, keel 5, fiber reinforced device board 7 and several electric heating plates 3, then clean the surface of the secondary lining 1 and repair the defective parts of the surface of the secondary lining 1.

[0053] S2: Select several U-shaped components 2, measure and lay out the U-shaped components 2 on the surface of the secondary lining 1, and install the U-shaped components 2. During the installation process, use a hand drill to drill holes at the laying-out positions, and then use expansion bolts 21 to fix the U-shaped components. During installation, the opening direction of the U-shaped components 2 must be the same as the longitudinal direction of the tunnel corresponding to the opening. At the same time, the U-shaped components 2 are arranged in a matrix. The matrix arrangement of the U-shaped components 2 makes the tensile force applied to the insulation layer and other structures uniformly distributed, and it is not easy to cause stress concentration due to uneven tensile force distribution. At the same time, the matrix arrangement of the U-shaped components 2 makes the size of the electric heating plate 3 arranged in it uniform, which is convenient for design, production and transportation.

[0054] S3: Fix the heating plate 3 by means of the wing plate of the U-shaped component 2, then install the insulation plate 4 and press the insulation plate 4 so that the wing plate of the U-shaped component 2 enters the insulation plate 4.

[0055] The steps for installing insulation board 4 include:

[0056] S3-1: Cut the insulation board 4 according to the second lining dimensions;

[0057] S3-2: Press the insulation board 4 so that the wing plate of the U-shaped component 2 is embedded in the insulation board 4. Continue to push the insulation board 4 so that the side of the insulation board 4 closest to the heating plate 3 is tightly attached to the heating plate 3.

[0058] S4: An air passage is opened inside the insulation layer, and a monitoring component 8 is installed inside the air passage. In this embodiment, the monitoring component 8 includes a protrusion. Any side wall of the protrusion is bonded and fixed to the side wall of the air passage, and strain gauges are bonded and fixed to the other side walls of the protrusion. Then, a temperature acquisition component and a control component are installed inside the opening. The monitoring component 8, the temperature acquisition component, and the heating plate 3 are all electrically connected to the control component. The temperature acquisition component includes several contact temperature sensors, and the contact temperature sensors are evenly arranged along the opening. In this embodiment, the control component is a controller, and the strain gauges, contact temperature sensors, and heating plate 3 are all electrically connected to the controller.

[0059] The monitoring component 8 is used to collect the direction of gas flow inside the airway. The control component determines the location of the temperature difference in the insulation layer according to the gas flow pattern, and controls the temperature acquisition component to collect the temperature at the location of the temperature difference, obtain a set of temperature information, select the maximum value in the set of temperature information as the standard value, and then control the electric heating plate 3 to work according to the temperature information until the temperature information at the location of the temperature difference reaches the standard value.

[0060] After the thermal insulation layer is completed, during use, strain gauges continuously collect deformation information of each sidewall of the protrusion. Due to the different effects of sunlight or equipment heat radiation on the opening and its corresponding tunnel locations, temperature differences occur at different locations of the opening (for example, during the day, locations that are not exposed to sunlight and are far from the equipment may be less affected by sunlight and remain in a negative temperature state, while locations that are exposed to sunlight will experience a temperature difference as the daytime temperature gradually rises). As the gas expands due to heat, when a temperature difference occurs, the gas density on the side with higher temperature in the air passage is less than that on the side with lower temperature. At this time, a pressure difference occurs between the two sides of the gas. Under the action of air pressure, high-pressure gas (i.e., lower temperature gas) flows towards low-pressure gas (i.e., higher temperature gas), forming an airflow. When the airflow passes over the protrusion, the airflow impacts the protrusion, causing a small deformation on the surface of the protrusion. That is, the strain information collected by the strain gauge at this location changes. The direction of airflow can be determined by the location of the protrusion where the strain information changes, and the location of the temperature difference can be roughly determined based on the direction of airflow.

[0061] For example, when the strain information corresponding to the left side of the protrusion changes, it can be roughly determined that the direction of gas flow is from left to right. At this time, the temperature on the left side is lower than that on the right side. The controller controls the contact temperature sensors on both sides to work, and collects temperature information from different positions on the left and right sides to obtain a set of temperature information. The controller selects the maximum value from the set of temperature information and uses this value as the standard value. The controller starts the electric heating plates 3 on both sides to actively heat the remaining positions except for the standard value, while continuously collecting temperature information until the temperature of all heated positions reaches the standard value, thus completing one active heat preservation of the secondary lining 1.

[0062] S5: Fix the keel 5 with the U-shaped component 2, and use self-tapping screws 6 to install the fiber reinforced device plate 7 on the side of the keel 5 away from the insulation board 4. In this embodiment, the self-tapping screw 6 is an FL self-tapping screw 6. Then fill the joint to complete the construction of the secondary lining 1 concrete heat insulation layer of the tunnel entrance section in the high-altitude cold region.

[0063] The steps for installing keel 5 include:

[0064] S5-1: Position the opening of the keel 5 toward the insulation board 4 and press the keel 5 so that the U-shaped component 2 passes through the keel 5 and the keel 5 is embedded in the insulation board 4;

[0065] S5-2: Bend the flanges of the U-shaped component 2 toward each other so that the flanges of the U-shaped component 2 cross and fasten to the keel 5, thus completing the installation of the keel 5.

[0066] In this embodiment, the insulation board 4 is made of polyphenolic foam with a thickness of not less than 50 millimeters. Compared to other solutions, the closed-cell structure of polyphenolic foam gives it lower air permeability, which reduces heat loss caused by convection between the air inside the airway and the air outside the insulation board 4 when the airway pressure changes. This also reduces the impact on the airway pressure and airflow, affecting the accuracy of the data collected by the monitoring component 8. Furthermore, it prevents external moisture from entering the airway, causing moisture retention that further affects the accuracy of the data collected by the monitoring component 8, and also prevents erosion of the U-shaped component 2, thus affecting the service life of the thermal insulation layer.

[0067] Example 2

[0068] As attached Figure 6As shown, the difference from the above embodiment is that: the monitoring component 8 in S4 includes a conductive rod 81 and several batteries. The conductive rod 81 is made of metal. An insulating cover 82 is sleeved on any end of the conductive rod 81. The insulating cover 82 is bonded and fixed to the side wall of the airway. Several conductive strips 83 are embedded and bonded to the insulating cover 82. The number of batteries electrically connected to the conductive strips 83 is different. A current sensor is electrically connected to the conductive rod 81. The current sensor is used to collect the current information passing through the conductive rod 81. The controller determines the position of the conductive strips 83 electrically connected to the conductive rod 81 based on the current information and obtains the gas flow direction in the airway based on the position of the conductive strips 83.

[0069] In this embodiment, the temperature acquisition component includes an infrared temperature sensor and a multi-axis motion platform. In this embodiment, the multi-axis motion platform is model PY69358. The infrared sensor and the multi-axis motion platform are fixedly connected by bolts, and the multi-axis fixed platform is installed inside the port.

[0070] The controller, infrared temperature sensor, multi-axis motion platform, and current sensor are all electrically connected to the controller.

[0071] The specific implementation method is as follows: When using this solution, the current sensor continuously collects the current information passing through the conductive rod 81. In the initial state, there is no temperature difference on the surface of the secondary lining 1, and no airflow is generated in the air passage. The conductive rod 81 is not subjected to external force and is in the initial state, not in contact with any conductive strip 83. At this time, the circuit where the current sensor is located is disconnected, and the current information collected by the current sensor is zero. When a temperature difference appears on the surface of the secondary lining 1, a pressure difference appears at various locations in the air passage, and airflow begins to appear. At this time, the airflow causes the conductive rod 81 to tilt. At a certain moment, the conductive rod 81 contacts the conductive strip 83, the circuit is connected, and it is electrically connected to the conductive strip 83. All connected batteries are connected to the circuit, generating current and thus current information. Since the current of a single battery and the connection scheme between batteries are known, the controller can determine the number of batteries connected to the circuit based on the magnitude of the current information. This allows the controller to determine the position of the conductive strip 83 in contact with the conductive rod 81 and the tilt direction of the conductive rod 81, thereby obtaining the direction of gas flow within the airway. The controller then controls the infrared temperature sensor and simultaneously controls the multi-axis motion platform. The multi-axis motion platform rotates the infrared temperature sensor, changing its acquisition position and obtaining a set of corresponding temperature information. The controller uses the maximum value from this set of temperature information as the standard value and controls the corresponding heating plate 3 to operate. The heating plate 3 heats the areas with temperature differences, ensuring that the temperature at each heated area reaches the standard value.

[0072] Compared to the previous embodiment, the design of the conductive rod 81 and conductive strip 83 in this solution increases the directional range that the monitoring component 8 can monitor by increasing the number of conductive strips 83. In contrast, the previous solution required changing the shape of the protrusion and increasing the number of strain gauges to increase the number of monitoring directions. Therefore, the cost per monitoring direction in this solution gradually decreases as the number of detection directions increases. Furthermore, since the sensor in this solution can be installed outside the airway, it facilitates inspection and maintenance after construction, reducing maintenance steps and costs for later maintenance personnel. In addition, the sensor in this solution is less affected by temperature, resulting in higher accuracy of the collected data.

[0073] Meanwhile, since the insulation layer uses polyphenolic foam material, its internal air bubbles are independent. When external mechanical vibration is transmitted into the air duct, the insulation board 4 can absorb the energy of the vibration through the deformation of the bubble wall, thereby reducing the impact of mechanical vibration on the monitoring component 8 after construction is completed.

[0074] In this solution, the infrared temperature sensor is combined with a multi-axis motion platform. Compared to the previous embodiment, the number of sensors is significantly reduced, which helps to lower the cost. Furthermore, since the infrared temperature sensor enables non-contact temperature measurement, this solution can be designed externally to the insulation layer, facilitating post-construction monitoring, maintenance, or replacement. Moreover, through the continuous operation of the infrared temperature sensor, this solution can acquire temperature information from multiple locations, resulting in a wider data coverage area and less susceptibility to sudden temperature changes compared to the previous embodiment.

[0075] Meanwhile, after the work is completed, operators can also use infrared temperature sensors to further assess the airtightness of the insulation layer. That is, by judging whether there are abnormal data in a set of temperature information collected, such as a sudden drop or increase in temperature in a certain set of temperature information, cracks may appear in that area, causing heat convection between that location and the outside.

[0076] Example 3

[0077] The difference from the above embodiment is that in S1, a photovoltaic solar power generation module (not shown in the figure) is selected. According to the geographical conditions of the opening, the location with the longest sunshine duration is selected to install the photovoltaic solar power generation module. The photovoltaic solar power generation module is used to supply power to the electric heating plate 3, the monitoring module 8, the temperature acquisition module and the control module.

[0078] The photovoltaic solar power generation module includes photovoltaic cells, solar panels, and inverters. The electric heating plate 3, monitoring component 8, temperature acquisition component, and control are all electrically connected to the photovoltaic cells. The temperature acquisition component is also used to collect the temperature of the solar panels. The control component determines the current sunshine conditions based on the temperature of the solar panels and controls the operation of the electric heating plate 3 based on the current sunshine conditions.

[0079] The specific implementation method is as follows: When using this solution, solar panels are installed at the location with the longest sunshine duration according to the geographical conditions of the tunnel entrance, so as to increase the power generation of the photovoltaic solar power generation module. This solution makes full use of the characteristics of strong radiation and abundant sunshine in high-altitude and cold regions through photovoltaic solar power generation modules to provide independent power for the structure used for active insulation, thereby reducing post-construction energy consumption.

[0080] During this process, the temperature acquisition components, such as the controller, intermittently control the infrared temperature sensor to work, and drive the infrared temperature sensor to rotate through the multi-axis fixed platform to collect the temperature of the solar panel. Since the solar panel has a significant temperature difference when exposed to sunlight and when not exposed to sunlight, the controller can determine whether the location of the opening is under sunlight based on the temperature change. When the location of the opening is under sunlight, and a temperature difference appears on the surface of the secondary lining 1, the controller controls the temperature acquisition components to work and selects a standard value. At this time, the standard value may be high, and a high temperature can easily cause the insulation board 4 to expand, thereby affecting the stability of the structure.

[0081] At this point, the controller selects the average value in the temperature information set as the standard value for subsequent heating. Compared to heating only the negative temperature position to the positive temperature, this solution can avoid large temperature differences on the secondary lining 1, which would cause inconsistent expansion and contraction at different positions of the secondary lining 1 and affect the structural stability.

Claims

1. A method for constructing a secondary lining concrete thermal insulation layer for tunnel entrance sections in high-altitude and cold regions, characterized in that: S1: Select insulation board (4), keel (5), fiber reinforced device board (7) and several electric heating plates (3), then clean the surface of the secondary lining (1) and repair the defective parts of the surface of the secondary lining (1); S2: Select several U-shaped components (2), measure and lay out the U-shaped components (2) on the surface of the secondary lining (1) and install them. S3: Fix the heating plate (3) by means of the wing plate of the U-shaped member (2), then install the insulation plate (4) and press the insulation plate (4) so ​​that the wing plate of the U-shaped member (2) enters the insulation plate (4): S4: An air passage is opened in the heat insulation layer, and a monitoring component (8) is installed in the air passage. Then, a temperature acquisition component and a control component are installed inside the opening. The monitoring component (8), the temperature acquisition component and the electric heating plate (3) are all electrically connected to the control component. The monitoring component (8) is used to collect the gas flow direction inside the airway. The control component determines the location of the temperature difference in the heat insulation layer according to the gas flow direction, and controls the temperature acquisition component to collect the temperature at the location of the temperature difference, obtain a set of temperature information, select the maximum value in the set of temperature information as the standard value, and then control the electric heating plate (3) to work according to the temperature information until the temperature information at the location of the temperature difference reaches the standard value. S5: Fix the keel (5) with the U-shaped component (2), and use self-tapping screws (6) to install the fiber reinforced device plate (7) on the side of the keel (5) away from the insulation board (4), and then fill the joint to complete the construction of the secondary lining (1) concrete heat insulation layer of the tunnel entrance section in the high-altitude cold region.

2. The construction method for secondary lining concrete thermal insulation layer of tunnel entrance section in high-altitude and cold regions according to claim 1, characterized in that: In S1, a photovoltaic solar power generation component is selected. Based on the geographical conditions of the cave entrance, the photovoltaic solar power generation component is installed at the location with the longest sunshine duration. The photovoltaic solar power generation component is used to supply power to the electric heating plate (3), the monitoring component (8), the temperature acquisition component, and the control component.

3. The construction method for secondary lining concrete thermal insulation layer of tunnel entrance section in high-altitude and cold regions according to claim 1, characterized in that: The monitoring component (8) in S4 includes a conductive rod (81) and several batteries. The conductive rod (81) is made of metal. An insulating cover (82) is fitted on any end of the conductive rod (81). The insulating cover (82) is fixedly connected to the side wall of the airway. Several conductive strips (83) are fixedly connected to the insulating cover (82). The number of batteries electrically connected to the conductive strips (83) is different. A current sensor is electrically connected to the conductive rod (81). The current sensor is used to collect the current information passing through the conductive rod (81). The conductive strips (83) are used to connect the circuit of the current sensor and the batteries. The control component determines the position of the conductive strips (83) electrically connected to the conductive rod (81) according to the current information, and obtains the gas flow direction in the airway according to the position of the conductive strips (83).

4. The construction method for secondary lining concrete thermal insulation layer of tunnel entrance section in high-altitude and cold regions according to claim 1, characterized in that: The temperature acquisition component includes an infrared temperature sensor and a multi-axis motion platform. The infrared temperature sensor is fixedly connected to the multi-axis motion platform, which is installed inside the opening.

5. The construction method of secondary lining (1) concrete thermal insulation layer for tunnel entrance section in high-altitude and cold regions according to claim 1, characterized in that: In S2, the U-shaped components (2) are arranged in a matrix.

6. The construction method of secondary lining (1) concrete thermal insulation layer for tunnel entrance section in high-altitude and cold regions according to claim 1, characterized in that: The steps for installing the insulation board (4) in S3 include: S3-1: Cut the insulation board (4) according to the secondary lining dimensions; S3-2: Press the insulation board (4) so ​​that the wing plate of the U-shaped member (2) is embedded in the insulation board (4), and continue to push the insulation board (4) so ​​that the side of the insulation board (4) close to the electric heating plate (3) is in contact with the electric heating plate (3).

7. The construction method of secondary lining (1) concrete thermal insulation layer for tunnel entrance section in high-altitude and cold regions according to claim 1, characterized in that: The steps for fixing the keel (5) in S5 include: S5-1: Position the opening of the keel (5) toward the insulation board (4) and press the keel (5) so that the U-shaped member (2) passes through the keel (5) and the keel (5) is embedded in the insulation board (4); S5-2: Bend the wing plates of the U-shaped component (2) toward each other so that the wing plates of the U-shaped component (2) cross and fasten to the keel (5), thus completing the installation of the keel (5).

8. The construction method of secondary lining (1) concrete thermal insulation layer for tunnel entrance section in high-altitude and cold regions according to claim 1, characterized in that: After the joints in S5 are filled, a vacuum pump is used to create negative pressure inside the thermal insulation layer, and the change in air pressure inside the thermal insulation layer is continuously monitored. Only when the difference in air pressure change within a set time is less than the preset value, the air pressure in the thermal insulation layer is brought back to atmospheric pressure by the vacuum pump.

9. The construction method of secondary lining (1) concrete thermal insulation layer for tunnel entrance section in high-altitude and cold regions according to claim 1, characterized in that: The insulation board (4) mentioned in S1 is made of polyphenolic foam material and has a thickness of not less than fifty millimeters.

10. The construction method of secondary lining (1) concrete thermal insulation layer for tunnel entrance section in high-altitude and cold regions according to claim 2, characterized in that: The photovoltaic solar power generation component includes photovoltaic cells, solar panels and inverters. The temperature acquisition component is also used to collect the temperature of the solar panels. The control component determines the current sunshine conditions based on the temperature of the solar panels and controls the electric heating plate (3) to work based on the current sunshine conditions.

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