Anti-freezing method for fire-fighting water supply pipeline outside tunnel hole

Abstract

The invention discloses an anti-freezing method for a fire-fighting water supply pipeline outside a tunnel hole. The anti-freezing method comprises the following steps: installing a pipeline and fire hydrant equipment in the tunnel hole; fire-fighting pipelines and valves outside the tunnel hole are installed and laid; mounting of a pressure boosting and stabilizing pump set in the pump room is completed, and the pressure boosting and stabilizing pump set is connected with a fire-fighting pipeline outside the tunnel hole; installing an isolation device; fire-fighting water is filled in inner and outer pipe networks of the tunnel; fire-fighting water in the fire-fighting pipe outside the cavity is drained; the isolating device and the fire-fighting pipe outside the tunnel are filled with pressure anti-freezing fire-fighting liquid; after filling is completed, the valve on the water outlet pipe of the fire pump and the valve on the water outlet pipe of the stabilized pressure pump are opened, and the isolation device is in a servo state; when the pipe network has small leakage at ordinary times, the stabilized pressure pump extracts the anti-freezing fire-fighting liquid from the liquid storage tank and supplements the anti-freezing fire-fighting liquid into a fire-fighting pipeline outside the tunnel; when a fire occurs, the fire pump sucks water from the fire pool and replenishes water to the pipe network to complete the fire extinguishing process. The anti-freezing problem of the fire-fighting water supply pipeline from the fire-fighting water pump to the tunnel portal in the alpine region can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of anti-freezing of tunnel fire-fighting water supply pipelines in alpine and high-altitude areas, and more particularly relates to an anti-freezing method for fire-fighting water supply pipelines outside a tunnel, which is applicable to the situation where the pipelines outside the tunnel cannot be laid below the freezing line, and realizes the anti-freezing of the fire-fighting water supply pipelines outside the tunnel. Background Art

[0002] In alpine and high-altitude areas, the construction of highway tunnels plays an extremely important role. First of all, it greatly improves the local traffic conditions, can shorten the driving time over the mountain from several hours in the past to 10 minutes, realizes all-weather traffic throughout the year, effectively solves the problem of traffic interruption caused by bad weather in alpine and high-altitude areas, and improves the reliability and efficiency of traffic.

[0003] Secondly, the construction of highway tunnels strongly promotes the local economic development. The improvement of traffic conditions enables resources to be transported out more conveniently, and at the same time attracts more investments and tourists, bringing more economic opportunities to the local area. In addition, the construction of highway tunnels also strengthens the connection between different regions and promotes the economic and cultural exchanges between regions.

[0004] As an important traffic node and storage facility, the highway tunnel fire-fighting system is the core facility to ensure traffic safety and life and property safety. The design and application of its fire-fighting system are crucial, especially in alpine regions, and its importance is mainly reflected in three aspects:

[0005] First, as a closed space, when a fire occurs in a tunnel, thick smoke and high temperature spread rapidly, and it is difficult to evacuate people. The fire-fighting system (such as fire hydrants, sprinkler devices, etc.) can quickly suppress the spread of fire and create a critical time window for escape and rescue;

[0006] Second, the dense vehicles, electrical equipment and the structure itself in the tunnel are easily damaged in a fire, which may lead to traffic paralysis and huge economic losses. For example, a certain tunnel in Jinan once failed the system due to the freezing and cracking of the fire-fighting water pipe, exposing the urgency of the anti-freezing problem;

[0007] Third, national regulations clearly require that reliable anti-freezing measures should be adopted in severe cold areas to ensure stable water supply during a fire. At present, the water fire-fighting system has become the main application method of the tunnel fire-fighting system due to its reliability, easy maintenance and low cost, but it faces severe challenges in extremely cold environments below -15°C, especially the anti-freezing problem of the pipelines outside the tunnel needs to be urgently broken through.

[0008] The expansion of water upon freezing is a major challenge for water fire protection systems in alpine regions. When water freezes below zero degrees Celsius, its volume expands by approximately 9%, generating ice blocks that increase the internal pressure of pipelines and equipment. This pressure change can lead to pipeline bursts, equipment damage, or system failures, and even trigger safety accidents. To address this issue, the current measures are as follows:

[0009] First, bury the pipelines deeply, laying the out-of-hole pipelines below the frost line. Laying the out-of-hole pipelines below the frost line is a traditional anti-freezing strategy, especially suitable for alpine regions. Its main advantages include:

[0010] 1. Effective anti-freezing. Deeply buried pipelines can directly utilize the heat preservation performance of the soil to prevent the medium from freezing, thus avoiding pipeline ruptures caused by freezing and significantly reducing the freezing risk.

[0011] 2. Save materials and costs. Compared with the schemes of overhead laying or shallow burial with insulation layers and electric tracing, deeply buried pipelines do not require additional insulation materials and electric tracing equipment, reducing the initial investment. At the same time, it avoids the maintenance costs brought by the aging of insulation layers and electric tracing tapes.

[0012] 3. Concealment and safety. Buried pipelines do not occupy ground space, do not affect traffic and aesthetics, and have good concealment, with a relatively low risk of being damaged by external machinery (such as vehicle rolling). In extremely low-temperature regions (such as where the frozen soil depth exceeds 2 meters), deep burial is a reliable option for key systems such as water supply and fire protection for long-term stable operation.

[0013] However, deeply buried pipelines also have some significant limitations in practical applications:

[0014] 1. The applicability is restricted by various factors. For the situation where the tunnel entrance is connected to a bridge, the deep burial method is difficult to implement.

[0015] 2. High construction difficulty and cost. In areas with deep frozen soil or complex geological conditions (such as rock layers), special technologies such as blasting are required for excavating deep trenches, resulting in a long construction period and a significant increase in costs. For example, in the city of Kiruna, Sweden, due to the shallow rock cover, the installation cost of deeply buried pipelines is extremely high.

[0016] 3. Difficult maintenance. When there is a pipeline leak or failure, it is necessary to excavate the ground for repair, which is time-consuming and laborious and may damage the surrounding facilities. For example, once a buried fire pipeline leaks, it is necessary to carry out large-scale road demolition to locate the problem.

[0017] 4. Restricted by geological conditions. In areas with high groundwater levels, soft soil, or frost-heaving soils (such as clay), deep burial may cause the pipeline to be affected by buoyancy or frost-heaving forces, requiring additional reinforcement measures. In addition, deep burial may cause ground settlement (such as in sandy soils) or damage to vegetation.

[0018] 5. Lack of flexibility. Deep-buried pipelines are not convenient for installing auxiliary facilities such as valves and instruments, and additional inspection wells need to be set up, increasing the system complexity.

[0019] 6. Risk of local freezing. Even if the burial depth meets the standard, the inner wall of large-diameter pipelines may still freeze due to low medium flow velocity or long-term stagnation, resulting in limited flow and difficult cleaning.

[0020] In summary, deep-buried pipelines are an anti-freezing strategy widely used in tunnel fire protection systems in alpine regions, especially suitable for key systems with long-term stable operation. However, its sensitivity and limitations to geological conditions, as well as construction difficulties and inconvenient maintenance, limit its application in complex environments.

[0021] The second is to adopt the anti-freezing technology of the electric tracing system. In alpine regions, the electric tracing system is widely used in the heat preservation of fire protection water pipes due to its significant anti-freezing advantages, and can effectively solve the icing problem through constant temperature control and the characteristic of no need for fuel. However, this system also has some limitations, as follows:

[0022] 1. High initial investment cost: The initial investment of the electric tracing system is relatively large, mainly due to the need for additional electrical equipment, electric heating elements and related control systems. In the application of long-distance pipelines or large-area regions, its initial cost is particularly significant.

[0023] 2. Strong dependence on electricity: The operation of the electric tracing system completely depends on the power supply. Once the power is interrupted, the system will not be able to work properly, which may cause potential safety hazards.

[0024] 3. Energy consumption problem: Although the electric tracing system has certain energy-saving advantages, in alpine regions, its energy consumption may be relatively high, especially when the temperature requirement is high, which may lead to an increase in power consumption.

[0025] 4. System complexity: The electric tracing system needs to be integrated with the fire protection system, increasing the system complexity and possibly requiring more monitoring and maintenance work.

[0026] 5. Potential safety hazards: If the electric tracing system fails, it may cause the temperature of the fire protection water pipe to be too high or too low, thus triggering potential safety hazards.

[0027] In summary, as an effective antifreeze technology, the electric heating system has important application value in the insulation of fire-fighting pipes in high-cold areas. However, in practical applications, it is restricted by factors such as initial investment, electricity dependence, energy consumption, system complexity and potential safety risks. In the fire-fighting pipes in the tunnel, the electric heating system shows high insulation reliability and low energy consumption, while outside the tunnel, the ambient temperature is usually lower than that inside the tunnel and is greatly affected by seasonal climate change. In this environment, the energy consumption of the electric heating system increases significantly and the insulation reliability is poor. In addition, the complexity of the environment outside the tunnel (such as wind and snow, frozen soil, etc.) also increases the operating risk and maintenance difficulty of the electric heating system. Therefore, when selecting antifreeze technology, the combination of the electric heating system and other antifreeze measures should be comprehensively considered according to the specific engineering environment and operating conditions to achieve the best antifreeze effect and economic benefits.

[0028] The third is to fill the fire-fighting pipe system with antifreeze. By adding antifreeze, water and ice form a viscoelastic substance, which can effectively prevent ice expansion.

[0029] As an effective antifreeze measure, antifreeze can form a viscoelastic substance by mixing with water, lowering the freezing point of water, thereby effectively preventing the medium from freezing and expanding in a low-temperature environment, thus ensuring the normal operation of the fire protection system. This characteristic makes it of great application value in the antifreeze of fire protection pipe systems, especially suitable for high-cold areas and low-temperature environments. However, the application of antifreeze also has certain limitations:

[0030] 1. High cost: The price of antifreeze liquid is usually high. At present, the application of antifreeze in tunnel fire protection system usually fills the entire pipeline system. The large-scale use of antifreeze will significantly increase the initial investment and maintenance cost of the system.

[0031] 2. Need to be replaced regularly: The performance of antifreeze will gradually decline over time or due to environmental changes, so it needs to be replaced regularly to maintain its antifreeze effect. This process not only increases management costs, but may also lead to the complexity of operation and maintenance.

[0032] 3. May affect system performance: If the amount of antifreeze added is inappropriate or the quality is not up to standard, it may have a negative impact on the performance of the fire protection system. For example, excessive antifreeze may cause pressure changes in the system or corrode the pipes, and even affect the normal operation of the system.

[0033] 4. Environmental impact: Antifreeze usually contains chemicals, and long-term use or improper storage may cause environmental pollution. Therefore, antifreeze waste needs to be properly disposed of to avoid harm to the environment.

[0034] 5. Operational complexity: The use of antifreeze may require professionals for operation, especially during the processes of addition, replacement, and maintenance. This not only increases the technical requirements for maintenance personnel but also may result in additional labor costs.

[0035] 6. Limited usage conditions: In extra-long tunnels or at the entrance (adverse slope) of the pump house located at the lower end of the tunnel, the high-viscosity characteristics of antifreeze may have a significant impact on the hydraulic performance of the system. Especially in alpine regions, the lower the temperature, the greater the viscosity of the antifreeze, resulting in an increase in the head loss of the pipe network and a higher demand for the pump head. This may cause the system to be unable to meet the service head requirements at the most unfavorable point in the tunnel.

[0036] In summary, as an effective antifreeze measure, antifreeze has important application value in the fire protection pipeline system, especially in the low-temperature environment of alpine regions. However, its application is also restricted by various factors such as cost, maintenance, system performance, environmental impact, and operational complexity. Under the conditions of extra-long tunnels and specific geographical conditions, the high-viscosity characteristics of antifreeze may lead to a decline in hydraulic performance and affect the normal operation of the system.

[0037] Fourth, the fire protection pipeline adopts an empty-pipe operation mode. In the tunnel fire protection water supply system, although the empty-pipe operation mode can effectively avoid the phenomenon of pipeline freezing, due to the long length of the tunnel water supply pipeline, the time required for water filling is relatively long, resulting in the inability to provide water source in a timely manner during a fire, thus delaying the best opportunity for fire extinguishing. Summary of the Invention

[0038] Aiming at the defects existing in the above-mentioned prior art, the technical problem to be solved by the present invention is to provide an antifreeze method for the fire protection water supply pipeline outside the tunnel, which solves the problem of antifreeze for the fire protection water supply pipeline from the fire pump to the tunnel entrance in alpine regions. This method is particularly applicable to the treatment of freeze damage of the fire protection water supply pipeline outside the tunnel of the existing operating tunnels in alpine regions, does not affect the original fire pipeline insulation system in the tunnel, does not require additional power supply and pumps, and has fast construction and simple maintenance.

[0039] To achieve the above purpose, the present invention adopts the following technical solutions:

[0040] The antifreeze method for the fire protection water supply pipeline outside the tunnel of the present invention comprises the following steps:

[0041] Step S1: Install the pipelines, valves, and fire hydrant equipment inside the tunnel to ensure correct installation.

[0042] Step S2: Complete the installation and laying of the fire protection pipelines and valves outside the tunnel.

[0043] Step S3: Complete the installation of the booster and pressure stabilizing pump set in the pump house and connect it to the fire protection pipeline outside the tunnel.

[0044] Step S4: Install the isolation device. Install the isolation device in the chamber reserved on the side wall of the tunnel entrance. Connect the water outlet end of the isolation device to the fire hydrant pipe network inside the system-side tunnel, and connect the water inlet end of the isolation device to the fire protection pipe network outside the supply-side tunnel. The isolation device mainly consists of a valve body, a valve flap, a pressure switch, a hydraulic alarm bell, a delay device, a compensator, a signal valve on the system side, a signal valve on the supply side, an alarm test valve, a drain valve, a first valve, a second valve, a third valve, a drain pipe, a pressure gauge on the supply side, and a pressure gauge on the system side. The valve flap is located in the valve body and divides the isolation device into an upper chamber and a lower chamber. The upper chamber of the isolation device is connected to the fire hydrant pipe network inside the system-side tunnel, and the lower chamber of the isolation device is connected to the fire protection pipe network outside the supply-side tunnel.

[0045] Step S5: Fill the fire protection water into the pipe networks inside and outside the tunnel. After ensuring that the above steps are correctly installed without errors, open the signal valve on the system side, the signal valve on the supply side, the second valve, and the third valve, and close the alarm test valve, the drain valve, and the first valve. Then fill the pipe network with water. After ensuring that the pressure of the fire hydrant inside the tunnel reaches the requirement, stop the fire pump of the pressurization and pressure stabilization pump group, and close the fourth valve on the outlet pipe of the fire pump and the fifth valve on the outlet pipe of the pressure stabilization pump of the pressurization and pressure stabilization pump group.

[0046] Step S6: Drain the fire protection water in the fire protection pipe outside the tunnel. Close the signal valve on the system side of the isolation device, open the signal valve on the supply side of the isolation device and the drain valve on the outside pipe, and drain the fire protection water in the outside pipe.

[0047] Step S7: Fill the isolation device and the fire protection pipe outside the tunnel with pressurized anti-freeze fire protection liquid. Open the fifth valve on the outlet pipe of the pressure stabilization pump, start the pressure stabilization pump, and the suction pipe of the pressure stabilization pump sucks the anti-freeze fire protection liquid in the liquid storage tank and transports it into the fire protection pipe outside the tunnel to fill the fire protection pipe outside the tunnel. Then, through pressure testing and acoustic detection methods, determine that the fire protection pipe outside the tunnel is filled with anti-freeze fire protection liquid and meets the pipe network pressure requirements and there are no leakage points.

[0048] Step S8: After the filling is completed, open the fourth valve on the outlet pipe of the fire pump and the fifth valve on the outlet pipe of the pressure stabilization pump, and the isolation device is in the standby state.

[0049] Step S9: When there is a small leakage in the pipe network usually, the pressure stabilization pump extracts the anti-freeze fire protection liquid from the liquid storage tank and supplements it into the fire protection pipe outside the tunnel.

[0050] Step S10: When a fire breaks out, the water spray from the fire hydrant causes the water in the fire hydrant pipe network in the system-side tunnel to change from a static state to a flowing state, and the pressure in the fire hydrant pipe network in the system-side tunnel drops accordingly. When the water pressure in the upper chamber of the isolation device is lower than the water pressure in the lower chamber, the valve flap is automatically opened under the action of the pressure difference. First, the antifreeze fire liquid in the external pipeline of the tunnel flows through the isolation device into the pipeline network in the tunnel, and then the fire water pumped by the fire pump flows through the isolation device into the pipeline network in the tunnel, and the passage leading to the hydraulic alarm bell is opened. At this time, the hydraulic alarm bell emits a sound alarm, and at the same time, the pressure switch acts and outputs a signal to start the fire pump. The fire pump draws water from the fire pool and replenishes water to the pipeline network to complete the fire extinguishing process.

[0051] Preferably, in the step S4, the valve body serves as the main structure, connecting the external fire pipeline network outside the water supply side tunnel and the fire hydrant pipeline network inside the system-side tunnel to form a water flow channel to ensure the transmission of water and pressure. The valve flap is located inside the valve body and usually remains closed by the balance of water pressure on both sides to prevent the water on the water supply side from flowing into the system side. During a fire, the use of the fire hydrant to extinguish the fire causes the pressure on the system side to drop, and the valve flap is opened under the pressure of the external fire pipeline network on the water supply side, allowing water to flow into the fire hydrant pipeline network inside the system-side tunnel to extinguish the fire. The delay device is connected to the upper chamber of the isolation device through a pipeline to buffer short-term pressure fluctuations and prevent false triggering of the alarm. There are small holes for drainage inside the delay device. When there are short-term fluctuations, the water flow will drain through the small holes and will not enter the alarm pipeline. Continuous water flow will fill the delay device and trigger the alarm.

[0052] Further, the pressure switch is connected to the delay device through the alarm pipeline. When water flows through the alarm pipeline, the pressure change triggers the closure of the internal electrical contacts, sending electrical signals to the fire pump and the monitoring center to start the fire pump and the audible and visual alarm device. The hydraulic alarm bell is connected to the delay device through the alarm pipeline. The water flow impacts the impeller to rotate, driving the alarm bell to emit a sound alarm to prompt the on-site personnel that the fire hydrant in the tunnel is working.

[0053] Preferably, the water supply side pressure gauge is connected to the lower chamber of the isolation device through the water supply side pipeline to monitor the real-time water pressure of the external fire pipeline network on the water supply side to ensure normal water source pressure. The third valve is installed on the water supply side pipeline. The system side pressure gauge is connected to the upper chamber of the isolation device through the system side pipeline to monitor the water pressure inside the fire hydrant pipeline network on the system side to verify the system tightness. If the pressure drops abnormally, it indicates leakage or valve failure. The second valve is installed on the system side pipeline. The compensator is installed on the pipeline between the water supply side pipeline and the system side pipeline to automatically compensate for the minor leakage of the fire hydrant pipeline network inside the system-side tunnel. By slowly replenishing water, it maintains the pressure balance on both sides of the valve flap to prevent the valve flap from being accidentally opened due to minor leakage. During normal leakage, the compensator allows a small amount of water to supplement the fire hydrant pipeline network inside the system-side tunnel. In case of a large amount of leakage, it will close to avoid continuous pressure relief.

[0054] Preferably, the drain valve and the drain pipe are used to empty the accumulated water in the fire hydrant pipe network on the system side of the tunnel for easy maintenance; usually, the alarm test valve is closed. When it is necessary to debug and maintain the isolation device, the alarm test valve is opened to check whether the alarm function of the hydraulic alarm bell is operating normally.

[0055] Further, the signal valve on the system side is a check valve, which is used to prevent water from flowing back from the fire hydrant pipe network on the system side of the tunnel to the isolation device, ensuring the correct water flow direction, preventing abnormal pressure fluctuations in the fire hydrant pipe network on the system side of the tunnel from damaging the isolation device, and extending the service life of the isolation device; during a fire, the signal valve on the system side ensures that water can flow smoothly into the fire hydrant pipe network on the system side of the tunnel, triggering the alarm device, thereby realizing the alarm function. During the maintenance and testing of the isolation device, it can be conveniently closed or opened for necessary inspections and repairs; the signal valve on the water supply side is a check valve, which is used to prevent water from flowing back to the water source, ensuring the correct water flow direction, preventing abnormal pressure fluctuations in the fire hydrant pipe network outside the tunnel on the water supply side from damaging the isolation device, and extending the service life of the isolation device; during a fire, the signal valve on the water supply side ensures that the water in the fire hydrant pipe network outside the tunnel on the water supply side can flow smoothly into the isolation device, triggering the alarm device, thereby realizing the alarm function. During the maintenance and testing of the isolation device, it can be conveniently closed or opened for necessary inspections and repairs.

[0056] Preferably, in step S3, the pressurized and stabilized pump group includes a fire pump and a pressure stabilizing pump connected to the fire pool.

[0057] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0058] 1. The application scenarios are more extensive and flexible. It is not limited to new projects, especially suitable for renovation projects. For the local renovation of filling fire-fighting liquid in the pipes outside the tunnel of the tunnel fire protection system, the construction period is short, the cost is low, and the impact on the anti-freezing system of the fire pipes in the tunnel is small.

[0059] 2. Compared with burying the fire pipes deeply for anti-freezing, the fire pipes in the present invention do not require digging deep trenches, are convenient for inspection and maintenance, and have a short construction period, which is particularly suitable for the situation where there is no roadbed at the tunnel entrance and the bridge and tunnel are connected.

[0060] 3. Compared with the full-line filling fire-fighting liquid system, it has a wider application range and can solve the problem that when the pump house is at the lower end of the tunnel entrance (reverse slope) and in the case of a very long tunnel, the pump pressure cannot make the most unfavorable point of the pipe network reach the minimum service head.

[0061] 4. Compared with the full-line filling fire-fighting liquid system, it is more convenient and fast to fill, discharge and collect the fire-fighting liquid.

[0062] 5. The isolation device controls the connection and disconnection of the media in the entire pipeline of the tunnel through hydraulic control (water pressure difference), which is safer and faster than electrical control (electric valves, etc.). In addition, warning bells, pressure switches and other devices are installed on this isolation device. The warning bell can inform the staff at the tunnel entrance of the working status of the fire hydrant in the tunnel, and its pressure switch directly starts the fire pump, adding another way to start the fire pump.

[0063] 6. Optimize the system design. The tunnel fire protection system is divided into two sections, inside the tunnel and outside the tunnel. Each section is equipped with an independent anti-freezing system. Through this sectional design, the system can effectively prevent the water body from freezing and expanding in a low-temperature environment, thereby reducing the risk of pipeline rupture caused by freezing, and at the same time significantly improving the reliability of fire protection water supply. In addition, the sectional design also facilitates the later maintenance and repair work, further improving the overall performance and management efficiency of the system.

[0064] 7. The anti-freezing fire protection liquid filled in the pipeline outside the tunnel has good anti-freezing performance and low cost compared with the electric tracing heating system: the lowest freezing point of the original liquid can reach -50°C, and it can be customized from -30°C to -50°C. After use, it has high-efficiency anti-freezing performance and can significantly reduce the construction and operation costs of anti-freezing the fire protection pipelines in cold-region tunnels in winter.

[0065] 8. The anti-freezing fire protection liquid filled in the pipeline outside the tunnel has good environmental protection performance compared with traditional antifreeze: According to the national standard GB17835-2008 "Water-based Fire Extinguishing Agents", the biological toxicity of the fire protection liquid is far lower than the limit value; it has passed more than 260 tests on chemical components that may be harmful to humans, animals, plants and the environment.

[0066] 9. The anti-freezing fire protection liquid filled in the pipeline outside the tunnel has good compatibility compared with traditional antifreeze: It has good compatibility with the aqueous film-forming agent (foam fire extinguishing agent) of the original water fire protection system, and the foaming index is equivalent to that of water.

[0067] 10. The anti-freezing fire protection liquid filled in the pipeline outside the tunnel is easier to spray compared with traditional antifreeze: It has low viscosity and small pipeline resistance. When using a fire protection spray gun to extinguish a fire, the spraying distance meets the fire protection design requirements; the head loss is smaller, reducing the pump head and lower energy consumption.

[0068] 11. The anti-freezing fire protection liquid filled in the pipeline outside the tunnel has good stability compared with traditional antifreeze: The material system of the fire protection liquid is stable, and the effect is long-lasting. It can be stably used in the pipeline for five years or more.

[0069] 12. The anti-freezing fire protection liquid filled in the pipeline outside the tunnel can be recycled compared with traditional antifreeze: After the fire protection liquid reaches the service life, because the anti-freezing and anti-icing agent in the solution decays very slowly, the waste fire protection liquid can be collected and stored and adjusted to be used as a road liquid snow melting agent. After testing, the effect is basically equivalent to that of the liquid snow melting agent of the same freezing point type.

[0070] 13. The antifreeze fire extinguishing liquid filled in the pipeline outside the tunnel has good fire extinguishing performance compared with traditional antifreeze and clean water. The fire extinguishing liquid has good flame retardancy. When the temperature is higher than 120 °C, the fire extinguishing liquid attached to the surface of the combustible gradually foams and wraps the surface of the combustible, achieving the effects of wetting, cooling and isolating air to extinguish the fire. According to the detection by the National Quality Supervision and Inspection Center for Fixed Fire Extinguishing Systems and Fire Resistant Components under the National Emergency Fire Management Department in accordance with the national standard GB17835-2008 "Water-based Fire Extinguishing Agents", the fire extinguishing performance of the fire extinguishing liquid is greater than 2A, that is, it can extinguish the fire of Class 2A carbonaceous solid combustibles.

[0071] 14. The antifreeze fire extinguishing liquid filled in the pipeline outside the tunnel has low corrosion compared with traditional antifreeze. After testing, the corrosion of the fire extinguishing liquid on carbon steel pipelines, aluminum parts, galvanized steel pipes, etc. is extremely low. Especially for the commonly used plastic-coated fire pipelines in fire protection, there is basically no corrosion. The fire extinguishing liquid has no obvious corrosion and aging promotion effects on concrete roads, asphalt roads, cables, rubber, etc.

[0072] 15. The antifreeze fire extinguishing liquid filled in the pipeline outside the tunnel has good anti-freezing and melting performance compared with traditional antifreeze. After the fire extinguishing liquid is repeatedly frozen and melted at low temperature (-70 °C), the relevant physical and chemical parameters remain stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] The drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application.

[0074] Figure 1 It is a comparison chart of the performance indexes of the environmentally friendly anti-corrosion and antifreeze fire extinguishing liquid product used in the present invention and relevant standards;

[0075] Figure 2 It is a schematic structural diagram of the partition device of the present invention (in the standby state);

[0076] Figure 3 It is a schematic structural diagram of the partition device of the present invention (in the fire extinguishing state);

[0077] Figure 4 It is a system diagram of the segmentation scheme of the present invention;

[0078] Figure 5 It is a flowchart of the fire extinguishing operation. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0079] Next, in combination with Figures 1 to 5 The antifreeze method for the fire water supply pipeline outside the tunnel provided by the present invention will be introduced in detail.

[0080] The present invention provides an anti-freezing method for the fire-fighting water supply pipeline outside the tunnel, which is applicable to alpine regions. This method fills the fire-fighting pipeline outside the tunnel with fire-fighting liquid and uses an isolation device to isolate the fire-fighting water in the fire-fighting pipeline inside the tunnel.

[0081] Taking the constant-pressure fire-fighting water supply system with a low-position water tank (fire-fighting water tank) + pressurization and pressure stabilization pump unit in the tunnel fire-fighting water supply system as an example, this method is described in detail. The fire-fighting pipeline from the fire-fighting water pump 16 connected to the fire-fighting water tank to the tunnel entrance is filled with highly efficient anti-freezing fire-fighting liquid, which has the properties of environmental protection, anti-freezing, corrosion resistance and flame retardancy. This kind of fire-fighting liquid can not only keep the fire-fighting system running normally at extremely low temperatures (such as -50°C), but also has the ability to extinguish fires and has no toxic effect on the environment. The fire-fighting pipeline inside the tunnel adopts conventional anti-freezing technologies, such as the electric tracing system, and the fire-fighting pipeline outside the tunnel (the fire-fighting water supply pipeline from the fire-fighting water pump 16 to the tunnel entrance) adopts a segmented anti-freezing scheme with fire-fighting liquid filling. The segmented point inside and outside the tunnel is in the fire-fighting trench at the starting point inside the tunnel, and the separation device used is an isolation device. The main body of the isolation device is the valve body 8, the valve flap 9 is located in the valve body 8 and divides the isolation device into an upper cavity and a lower cavity. The upper cavity of the isolation device is connected to the indoor fire hydrant pipe network on the system side, and the lower cavity of the isolation device is connected to the outdoor fire-fighting pipe network on the water supply side.

[0082] Under normal conditions, both the upper cavity (connected to the indoor fire hydrant pipe network on the system side) and the lower cavity (connected to the outdoor fire-fighting pipe network on the water supply side) of the isolation device are filled with water, and the valve flap 9 is in the closed state under the action of its own gravity and water pressure. When a fire occurs, the water used by the indoor fire hydrants in the tunnel causes the pressure of the indoor fire hydrant pipe network on the system side connected to the isolation device to drop rapidly, resulting in the pressure of the lower cavity being greater than that of the upper cavity. The valve flap 9 is pushed open, and the water in the outdoor fire-fighting pipe network on the water supply side flows into the indoor fire hydrant pipe network on the system side for water replenishment, connecting the fire-fighting liquid and fire-fighting water in the fire-fighting pipelines inside and outside the tunnel. The pressure switch 10 on the isolation device sends an alarm signal, and the pressurization and pressure stabilization pump unit replenishes water and pressurizes the pipelines inside and outside the tunnel to ensure the normal operation of the fire-fighting water supply system, quickly suppress the spread of the fire, and create a critical time window for escape and rescue. This method is especially applicable to the conditions where the tunnel is connected to a bridge and the roadbed outside the tunnel cannot be excavated.

[0083] To better illustrate the method of the present invention, the anti-freezing method for the fire-fighting water supply pipeline outside the tunnel of the present invention includes the following steps:

[0084] 1. Install the pipelines, valves and fittings, and fire hydrant equipment inside the tunnel to ensure correct installation.

[0085] 2. Complete the installation and laying of the fire-fighting pipelines and valves and fittings outside the tunnel.

[0086] 3. Complete the installation of the pressurization and pressure stabilization pump unit (including the fire-fighting water pump 16 connected to the fire-fighting water tank, the pressure stabilization pump 18 and related accessory fittings) in the pump room and connect it to the fire-fighting pipeline outside the tunnel.

[0087] 4. Install the isolation device: The isolation device mainly consists of a pressure switch 10, a hydraulic alarm bell 11, a delay unit 12, a compensator 15, a signal valve 1 on the system side, a signal valve 2 on the water supply side, an alarm test valve 3, a drain valve 4, a first valve 5, a second valve 6, a third valve 7, a throttle plate, a filter, a drain pipe, a water supply side pressure gauge 13, a system side pressure gauge 14, a valve body 8, and a valve flap 9.

[0088] The valve body 8 serves as the main structure, connecting the water supply side outdoor fire protection pipe network (including antifreeze fire protection liquid) and the system side indoor fire hydrant pipe network to form a water flow channel, ensuring the transmission of water and pressure.

[0089] The valve flap 9 is located inside the valve body 8. Usually, it remains closed relying on the balance of water pressure on both sides (water supply side water pressure = system side water pressure) to prevent the water on the water supply side from flowing into the system side. During a fire, when the fire hydrant is used to extinguish the fire, the pressure on the system side drops. The valve flap 9 is pushed open by the pressure of the water supply side outdoor fire protection pipe network, allowing water to flow into the system side indoor fire hydrant pipe network for fire extinguishing.

[0090] The delay unit 12 is connected to the upper cavity of the isolation device through a pipeline to buffer short-term pressure fluctuations (such as pump startup, pipeline water hammer) and prevent false alarms. There are small holes for drainage inside the delay unit 12. During short-term fluctuations, the water flow will drain through the small holes and will not enter the alarm pipeline; continuous water flow (such as a real fire alarm) will fill the delay unit 12 and trigger an alarm.

[0091] The pressure switch 10 is connected to the delay unit 12 through an alarm pipeline. When water flows through the alarm pipeline, the pressure change triggers the internal electrical contacts to close, sending an electrical signal to the fire pump 16 of the pressurization and pressure stabilization pump group and the monitoring center to start the fire pump 16 and the audible and visual alarm device.

[0092] The hydraulic alarm bell 11 is connected to the delay unit 12 through an alarm pipeline. The water flow impacts the impeller to rotate, driving the alarm bell to emit a sound alarm to prompt the on-site personnel that the indoor fire hydrant is in operation.

[0093] The water supply side pressure gauge 13 is connected to the lower cavity of the isolation device through the water supply side pipeline, used to monitor the real-time water pressure of the water supply side outdoor fire protection pipe network to ensure normal water source pressure. The third valve 7 is installed on the water supply side pipeline.

[0094] The system side pressure gauge 14 is connected to the upper cavity of the isolation device through the system side pipeline, used to monitor the water pressure inside the system side indoor fire hydrant pipe network to verify the system tightness. If the pressure drops abnormally, it may indicate leakage or valve failure. The second valve 6 is installed on the system side pipeline.

[0095] The compensator 15 (drip valve) is installed on the pipeline between the water supply side pipeline and the system side pipeline, and is used to automatically compensate for the minor leakage of the fire hydrant pipe network in the tunnel on the system side. By slowly replenishing water, it maintains the pressure balance on both sides of the valve flap 9, preventing the valve flap 9 from opening accidentally due to minor leakage. During normal leakage, the compensator 15 allows a small amount of water to supplement the fire hydrant pipe network in the tunnel on the system side; in case of large leakage, it will close to avoid continuous pressure relief.

[0096] The drain valve 4 and the drain pipe are used to drain the accumulated water in the fire hydrant pipe network in the tunnel on the system side, facilitating maintenance.

[0097] Normally, the alarm test valve 3 is usually closed. When it is necessary to debug and maintain the isolation device, opening the alarm test valve 3 can check whether the alarm function of the hydraulic alarm bell 11 is operating normally.

[0098] The system side signal valve 1 is a check valve, which is used to prevent water from flowing back from the fire hydrant pipe network in the tunnel on the system side to the isolation device, ensuring the correct water flow direction. It prevents abnormal pressure fluctuations in the fire hydrant pipe network in the tunnel on the system side from damaging the isolation device and extends the service life of the isolation device. During a fire, the system side signal valve 1 ensures that water can flow smoothly into the fire hydrant pipe network in the tunnel on the system side, triggering alarm devices (such as the hydraulic alarm bell 11 and the pressure switch 10), thus realizing the alarm function. It can be conveniently closed or opened during the maintenance and testing of the isolation device for necessary inspections and repairs.

[0099] The water supply side signal valve 2 is a check valve, which is used to prevent water from flowing back to the water source, ensuring the correct water flow direction. It prevents abnormal pressure fluctuations in the fire hydrant pipe network outside the tunnel on the water supply side from damaging the isolation device and extends the service life of the isolation device. During a fire, the water supply side signal valve 2 ensures that the water in the fire hydrant pipe network outside the tunnel on the water supply side can flow smoothly into the isolation device, triggering alarm devices (such as the hydraulic alarm bell 11 and the pressure switch 10), thus realizing the alarm function. It can be conveniently closed or opened during the maintenance and testing of the isolation device for necessary inspections and repairs.

[0100] The isolation device is installed in the cave room reserved on the side wall of the tunnel entrance. The water outlet end of the isolation device is connected to the main fire pipe (fire hydrant pipe network in the tunnel on the system side) in the fire trench, and the water inlet end of the isolation device is connected to the pipeline outside the cave (fire hydrant pipe network outside the tunnel on the water supply side).

[0101] 5. Fill the fire water into the pipe networks inside and outside the tunnel: After ensuring that all the above steps are correctly installed without errors, open the system side signal valve 1, the water supply side signal valve 2, the second valve 6, and the third valve 7, and close the alarm test valve 3, the drain valve 4, and the first valve 5. Then fill the pipe network with water. After ensuring that the pressure of the fire hydrants in the tunnel reaches the requirements, stop the fire pump 16, and close the fourth valve 17 on the outlet pipe of the fire pump 16 and the fifth valve 19 on the outlet pipe of the pressure stabilizing pump 18.

[0102] 6. Fire water in the fire pipes outside the drainage holes: Close the system-side signal valve 1 on the isolation device, open the water supply-side signal valve 2 on the isolation device and the drain valve on the pipeline outside the hole to drain the fire water in the pipeline outside the drainage holes. The discharged fire water is used to wash the road surface at the tunnel entrance or recycled for other purposes.

[0103] 7. The isolation device and the fire pipes outside the hole are filled with pressurized anti-freeze fire liquid: Open the fifth valve 19 on the water outlet pipe of the pressure stabilizing pump 18, start the pressure stabilizing pump 18. The suction pipe of the pressure stabilizing pump 18 sucks the anti-freeze fire liquid in the liquid storage tank 20 (liquid storage pool) and transports it into the fire pipes outside the hole to fill the fire pipes outside the hole. Determine through pressure testing and acoustic detection methods that the fire pipes outside the hole are filled with fire liquid and meet the requirements of the pipe network pressure and there are no leakage points.

[0104] 8. After the filling is completed, open the fourth valve 17 on the water outlet pipe of the fire water pump 16 and the fifth valve 19 on the water outlet pipe of the pressure stabilizing pump 18, and the isolation device is in the standby state.

[0105] 9. When there is a small leakage in the pipe network usually, the pressure stabilizing pump 18 extracts the anti-freeze fire liquid from the liquid storage tank 20 (liquid storage pool) and supplements it into the fire pipes outside the hole.

[0106] 10. When a fire occurs, the water spraying from the fire hydrant causes the water in the fire hydrant pipe network inside the hole on the system side to change from a static state to a flowing state, and the pressure of the fire hydrant pipe network inside the hole on the system side drops accordingly. When the water pressure in the upper cavity of the isolation device is lower than the water pressure in the lower cavity, the valve flap 9 automatically opens under the action of the pressure difference, and the water flow (first the anti-freeze fire liquid in the pipeline outside the hole, and then the fire water transported by the fire water pump 16) flows through the isolation device to the pipe network inside the hole (the fire hydrant pipe network inside the hole on the system side), and opens the passage leading to the hydraulic alarm bell 11. At this time, the hydraulic alarm bell 11 emits a sound alarm, and at the same time the pressure switch 10 acts and outputs a signal to start the fire water pump 16. The fire water pump 16 sucks water from the fire pool and replenishes water to the pipe network to complete the fire extinguishing process.

[0107] The above has introduced in detail a method for realizing the anti-freezing of the fire water supply pipeline outside the tunnel in alpine regions provided by the embodiment of the present invention. Through the above method, it is possible to effectively prevent problems such as pipe freeze expansion in the fire water supply pipeline outside the tunnel in alpine regions when the bridge and tunnel are connected outside the hole and there is no condition for deep-burying the pipeline, and keep the fire protection system running normally. And the alarm bell can be sounded at the tunnel entrance for real-time alarm to inform the staff near the entrance that the fire hydrant inside the tunnel is working.

[0108] This method is particularly applicable to the treatment of freeze damage of the fire water supply pipes outside the fire holes of the existing tunnels in alpine regions. It does not affect the insulation system of the original fire pipes in the tunnels, does not require additional power supply and water pumps, and the construction is fast and the maintenance is simple. The present invention only elaborates in detail on the application to the constant high-pressure water supply system. The anti-freezing method for the fire water supply pipes outside the tunnel can also be used for the anti-freezing of the fire pipe networks outside the tunnels in the constant high-pressure water supply system. The principle is generally the same and will not be elaborated further.

[0109] As mentioned above, it is only the specific implementation manner in the present invention, but the protection scope of the present invention is not limited thereto. Any transformation or replacement that can be understood by those who are familiar with the technology within the technical scope disclosed by the present invention should be covered within the scope of the present invention.

Claims

1. An anti-freezing method for the fire-fighting water supply pipeline outside the tunnel, characterized in that: The steps are as follows: Step S1: Install the pipelines, valves and valve parts, and fire hydrant equipment in the tunnel to ensure correct installation. Step S2: Complete the installation and laying of the fire pipelines and valves outside the tunnel. Step S3: Complete the installation of the pressurization and pressure stabilization pump set in the pump room and connect it to the fire pipeline outside the tunnel. Step S4: Install the isolation device. Install the isolation device in the cavity reserved on the side wall of the tunnel entrance. The water outlet end of the isolation device is connected to the fire hydrant pipe network in the tunnel on the system side, and the water inlet end of the isolation device is connected to the fire pipe network outside the tunnel on the water supply side. The isolation device mainly consists of a valve body (8), a valve flap (9), a pressure switch (10), a hydraulic alarm bell (11), a delay device (12), a compensator (15), a signal valve (1) on the system side, a signal valve (2) on the water supply side, an alarm test valve (3), a drain valve (4), a first valve (5), a second valve 6, a third valve (7), a drain pipe, a pressure gauge (13) on the water supply side, and a pressure gauge (14) on the system side. The valve flap (9) is located in the valve body (8) and divides the isolation device into an upper cavity and a lower cavity. The upper cavity of the isolation device is connected to the fire hydrant pipe network in the tunnel on the system side, and the lower cavity of the isolation device is connected to the fire pipe network outside the tunnel on the water supply side. Step S5: Fill the fire water into the pipe networks inside and outside the tunnel. After ensuring that the above steps are correctly installed, open the signal valve (1) on the system side, the signal valve (2) on the water supply side, the second valve (6), and the third valve (7), and close the alarm test valve (3), the drain valve (4), and the first valve (5). Then fill the pipe network with water. After ensuring that the pressure of the fire hydrant in the tunnel meets the requirements, stop the fire pump (16) of the pressurization and pressure stabilization pump set, and close the fourth valve (17) on the outlet pipe of the fire pump (16) and the fifth valve (19) on the outlet pipe of the pressure stabilization pump (18) of the pressurization and pressure stabilization pump set. Step S6: Drain the fire water in the fire pipe outside the tunnel. Close the signal valve (1) on the system side of the isolation device, open the signal valve (2) on the water supply side of the isolation device and the drain valve on the pipe outside the tunnel, and drain the fire water in the pipe outside the tunnel. Step S7: Fill the isolation device and the fire pipe outside the tunnel with pressurized antifreeze fire liquid. Open the fifth valve (19) on the outlet pipe of the pressure stabilization pump (18), start the pressure stabilization pump (18), and the suction pipe of the pressure stabilization pump (18) sucks the antifreeze fire liquid in the storage tank (20) and transports it into the fire pipe outside the tunnel to fill the fire pipe outside the tunnel. Then, through pressure testing and acoustic detection methods, determine that the fire pipe outside the tunnel is filled with antifreeze fire liquid and meets the pipe network pressure requirements and there are no leakage points. Step S8: After the filling is completed, open the fourth valve (17) on the outlet pipe of the fire pump (16) and the fifth valve (19) on the outlet pipe of the pressure stabilization pump (18), and the isolation device is in the standby state. Step S9: When there is a small leakage in the pipe network usually, the pressure stabilization pump (18) extracts the antifreeze fire liquid from the storage tank (20) and supplements it into the fire pipe outside the tunnel. Step S10: When a fire occurs, the water spray from the fire hydrant causes the water in the fire hydrant pipe network in the system-side tunnel to change from a static state to a flowing state, and the pressure in the system-side tunnel fire hydrant pipe network drops accordingly. When the water pressure in the upper chamber of the isolation device is lower than the water pressure in the lower chamber, the valve flap (9) is automatically opened under the action of the pressure difference. First, the antifreeze fire liquid in the outdoor pipeline, and then the fire water transported by the fire pump (16) flows through the isolation device into the pipeline network in the tunnel, and opens the channel leading to the hydraulic alarm bell (11). At this time, the hydraulic alarm bell (11) emits a sound alarm, and at the same time the pressure switch (10) operates and outputs a signal to start the fire pump (16). The fire pump (16) sucks water from the fire pool and replenishes water to the pipeline network to complete the fire extinguishing process.

2. The anti-freezing method of the fire-fighting water supply pipeline outside the tunnel according to claim 1, characterized in that: In the step S4, the valve body (8) serves as the main structure, connecting the outdoor fire pipeline network on the water supply side and the fire hydrant pipeline network in the system-side tunnel, forming a water flow channel to ensure the transmission of water and pressure; The valve flap (9) is located inside the valve body (8). Usually, it remains closed by the balance of water pressure on both sides to prevent the water on the water supply side from flowing into the system side. During a fire, the use of the fire hydrant to extinguish the fire causes the pressure on the system side to drop. The valve flap (9) is opened under the push of the pressure of the outdoor fire pipeline network on the water supply side, allowing water to flow into the fire hydrant pipeline network in the system-side tunnel to extinguish the fire; The delay device (12) is connected to the upper chamber of the isolation device through a pipeline to buffer short-term pressure fluctuations and prevent false triggering of the alarm. There are small holes for drainage inside the delay device (12). When there is a short-term fluctuation, the water flow will drain through the small holes and will not enter the alarm pipeline; continuous water flow will fill the delay device (12) and trigger the alarm.

3. The anti-freezing method of the fire-fighting water supply pipeline outside the tunnel according to claim 2, wherein: The pressure switch (10) is connected to the delay device (12) through the alarm pipeline. When water flows through the alarm pipeline, the pressure change triggers the internal electrical contacts to close, sending electrical signals to the fire pump (16) and the monitoring center to start the fire pump (16) and the audible and visual alarm device; The hydraulic alarm bell (11) is connected to the delay device (12) through the alarm pipeline. The impeller is rotated by the impact of water flow to drive the alarm bell to emit a sound alarm to prompt the on-site personnel that the fire hydrant in the tunnel is working.

4. The anti-freezing method of the fire-fighting water supply pipeline outside the tunnel according to claim 1, characterized in that: The water supply side pressure gauge (13) is connected to the lower chamber of the isolation device through the water supply side pipeline, used to monitor the real-time water pressure of the outdoor fire pipeline network on the water supply side to ensure normal water source pressure. The third valve (7) is installed on the water supply side pipeline; The system side pressure gauge (14) is connected to the upper chamber of the isolation device through the system side pipeline, used to monitor the water pressure in the fire hydrant pipeline network in the system-side tunnel to verify the system tightness; If the pressure drops abnormally, indicating leakage or valve failure, the second valve (6) is installed on the system side pipeline; The compensator (15) is installed on the pipeline between the water supply side pipeline and the system side pipeline, used to automatically compensate for the minor leakage of the fire hydrant pipeline network in the system-side tunnel, maintain the pressure balance on both sides of the valve flap (9) by slowly replenishing water, and prevent the valve flap (9) from being accidentally opened due to minor leakage. During normal leakage, the compensator (15) allows a small amount of water to supplement the fire hydrant pipeline network in the system-side tunnel; in case of large leakage, it will close to avoid continuous pressure relief.

5. The anti-freezing method for the fire water supply pipeline outside the tunnel according to claim 1, wherein: The drain valve (4) and the drain pipe are used to empty the accumulated water in the fire hydrant pipe network on the system side of the tunnel, which is convenient for maintenance; Normally, the alarm test valve (3) is usually closed. When it is necessary to debug and maintain the isolation device, the alarm test valve (3) is opened to check whether the alarm function of the hydraulic alarm bell (11) is operating normally.

6. The anti-freezing method of the fire water supply pipeline outside the tunnel according to claim 1, characterized in that: The system-side signal valve (1) is a check valve, which is used to prevent water from flowing back from the fire hydrant pipe network on the system side of the tunnel to the isolation device, ensuring the correct water flow direction, preventing abnormal pressure fluctuations in the fire hydrant pipe network on the system side of the tunnel from damaging the isolation device, and extending the service life of the isolation device; during a fire, the system-side signal valve (1) ensures that water can flow smoothly into the fire hydrant pipe network on the system side of the tunnel, triggering the alarm device, thereby realizing the alarm function. When maintaining and testing the isolation device, it can be conveniently closed or opened for necessary inspections and repairs; The water supply-side signal valve (2) is a check valve, which is used to prevent water from flowing back to the water source, ensuring the correct water flow direction, preventing abnormal pressure fluctuations in the fire hydrant pipe network outside the tunnel on the water supply side from damaging the isolation device, and extending the service life of the isolation device; during a fire, the water supply-side signal valve (2) ensures that the water in the fire hydrant pipe network outside the tunnel on the water supply side can flow smoothly into the isolation device, triggering the alarm device, thereby realizing the alarm function. When maintaining and testing the isolation device, it can be conveniently closed or opened for necessary inspections and repairs.

7. A method for preventing freezing of a fire water supply pipeline outside a tunnel according to claim 1, characterized in that: In the step S3, the pressurization and pressure stabilization pump set includes a fire pump (16) and a pressure stabilization pump (18) connected to the fire pool.

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