A method and system for locating a fire position and determining a fire power of a immersed tube tunnel

Abstract

The application discloses a method and system for positioning a fire location and measuring a fire power of a immersed tube tunnel, wherein the method comprises the following steps: detecting temperature data of the immersed tube tunnel in real time based on a temperature sensor; when temperature is abnormal, positioning a fire location based on a double-wavelength fire source detector and a temperature sensor, and obtaining a corresponding fire power by using a fire power calculation method based on the highest temperature data in the immersed tube tunnel; and evaluating a fire scale based on the fire power and generating a corresponding fire alarm signal. The application can accurately measure the fire power of a fire when the fire occurs, is used for assisting a monitoring platform in judging the fire scale, and can use a processing procedure different from that of a horizontal tunnel to measure the fire power in the immersed tube tunnel with different slopes, so that the fire extinguishing of the immersed tube tunnel is more targeted.

Description

Technical Field

[0001] This invention belongs to the field of fire detection technology, and in particular relates to a method and system for locating the fire location and measuring the fire source power in immersed tunnels. Background Technology

[0002] Immersed tunnels are a mode of transportation between sea areas, connecting land and sea through bridge and tunnel passages. This significantly reduces transportation distances and travel times between cities. The structure is stable, and natural disasters such as earthquakes and typhoons have minimal impact on it.

[0003] Compared to highway tunnels on land, smoke extraction and evacuation would be much more difficult if a fire broke out in an underwater immersed tunnel. This is because the immersed tunnel is buried deep underwater and has a certain slope when connecting to the land. This small and narrow space structure is not conducive to the ventilation of smoke and the evacuation of people, and it also increases the difficulty of fire control to a certain extent.

[0004] Moreover, because immersed tunnels are located underwater and the tunnel space is relatively enclosed, if a fire occurs and cannot be dealt with promptly and correctly, it will result in incalculable losses to the lives and property of people inside the tunnel and to public property.

[0005] As national construction standards continue to improve, the demand for immersed tunnels is gradually increasing. However, currently, there is no dedicated fire alarm system in China specifically designed for tunnels with excessive longitudinal slopes. Generally, fire alarm systems used in land-based horizontal tunnels are adopted, primarily relying on the alarm threshold of the tunnel's heat-sensing fiber optic cables. However, due to the inherent slope of immersed tunnels, the alarm systems used in land-based horizontal tunnels cannot be fully applied to immersed tunnel fire alarm systems. Furthermore, existing fire alarm systems, relying mainly on the alarm threshold of the tunnel's heat-sensing fiber optic cables, can only predict the scale of a fire and cannot more accurately respond to fires with less material and in a shorter time, thus failing to improve firefighting efficiency. Therefore, a new fire alarm system and method are urgently needed to solve these practical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a method and system for locating the fire location and measuring the fire source power in immersed tunnels, so as to solve the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides a method for locating the fire location and determining the fire source power in an immersed tunnel, comprising the following steps:

[0008] Real-time monitoring of immersed tunnel temperature data based on temperature sensors;

[0009] When the temperature is abnormal, the location of the fire source is located by using a dual-wavelength fire source detector and an auxiliary temperature sensor. At the same time, the corresponding fire source power is obtained by using the fire source power calculation method based on the highest temperature data in the immersed tunnel.

[0010] The fire scale is assessed based on the fire source power, and a corresponding fire alarm signal is generated.

[0011] Optionally, the deployment process of the temperature sensor includes: dividing the detection area of ​​the immersed tunnel into several fireproof zones, setting a preset installation distance from the top of the tunnel in each fireproof zone, setting a cable tray at the preset installation distance, arranging temperature sensors horizontally in a double-sided sine wave pattern along the tunnel length direction in the cable tray, and fixing them with fixing clamps at the peak values ​​of the sine waves; wherein, the temperature sensor is a fiber optic grating sensor.

[0012] Optionally, the method for calculating the power of the fire source is as follows:

[0013]

[0014] Where Q is the fire heat release rate, g is the gravitational acceleration, and T is the acceleration due to gravity. max T represents the maximum temperature measured by the fiber Bragg grating sensor. ∞ H represents the ambient temperature inside the tunnel. ef H represents the height from the surface of the fire source to the ceiling, and H represents the tunnel elevation difference.

[0015] Optionally, the fire scale includes at least ordinary fire, major fire, serious fire and especially serious fire.

[0016] Optionally, the process of generating the corresponding fire alarm signal includes: when the fire is a general fire or a relatively large fire, the corresponding fire alarm signal is uploaded to the immersed tunnel monitoring platform for processing; when the fire is a major fire or an extremely major fire, the corresponding fire alarm signal is uploaded to the local emergency management center for processing.

[0017] This invention also provides a system for locating the fire location and measuring the fire source power in immersed tunnels, comprising:

[0018] The temperature detection module is used to detect the temperature of the immersed tunnel in real time based on the temperature sensor.

[0019] A fire source location module, connected to the temperature detection module, is used to locate the fire source position based on a dual-wavelength fire source detector and an auxiliary temperature sensor when the temperature is abnormal.

[0020] A temperature processing module, connected to the fire source positioning module, is used to obtain the fire source power based on the highest temperature of the immersed tunnel using a fire source power calculation method.

[0021] A fire alarm module, connected to the temperature processing module, is used to determine the fire scale level based on the fire source power.

[0022] The fire monitoring module is connected to the fire alarm module and is used to monitor the location of the fire source, the power of the fire source, and the fire scale level in real time.

[0023] Optionally, the temperature detection module includes a detection area division unit and a sensor deployment unit;

[0024] The detection area division unit is used to divide the detection area of ​​the immersed tunnel into several fire protection zones; the sensor deployment unit is used to preset the installation distance from the top of the tunnel in each fire protection zone, set up a cable tray at the preset installation distance, arrange temperature sensors horizontally in a double sine wave pattern along the tunnel length direction in the cable tray, and fix them at the peak of the sine wave using a fixing clamp; wherein, the temperature sensor is a fiber optic grating sensor.

[0025] Optionally, the temperature processing module includes a temperature sorting unit and a power acquisition unit;

[0026] The temperature sorting unit is used to sort the immersed tunnel temperatures obtained by the temperature sensors to obtain the highest temperature of the immersed tunnel; the power acquisition unit is used to obtain the corresponding fire source power based on the gravitational acceleration, the highest temperature of the immersed tunnel, the ambient temperature inside the tunnel, the height from the surface of the fire source to the ceiling, and the elevation difference of the tunnel.

[0027] Optionally, the fire alarm module includes a classification unit and a signal pre-alarm unit;

[0028] The classification unit is used to classify the fire scale into four levels based on the fire source power: general fire, major fire, serious fire, and extremely serious fire. The signal alarm unit is used to upload the corresponding fire alarm signal to the immersed tunnel monitoring platform for processing when the fire scale is general fire or major fire, and to upload the corresponding fire alarm signal to the local emergency management center for processing when the fire scale is serious fire or extremely serious fire.

[0029] The technical effects of this invention are as follows:

[0030] This invention can accurately measure the power of the fire source when a fire occurs, which can be used to assist the monitoring platform in determining the scale of the fire. In immersed tunnels with different slopes, different procedures can be used to measure the power of the fire source, making fire fighting in immersed tunnels more targeted.

[0031] This invention deploys dual-wavelength flame detectors inside tunnels to determine the location of fire sources and further improve the accuracy of fire alarms. Attached Figure Description

[0032] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0033] Figure 1 This is a flowchart of the method for locating the fire location and measuring the fire source power in an immersed tunnel according to an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the installation of the dual-wavelength fire source detector in the immersed tunnel according to an embodiment of the present invention.

[0035] Figure 3 This is a schematic diagram of the distribution structure of the fiber optic grating sensor in the immersed tunnel according to an embodiment of the present invention;

[0036] Figure 4 This is a comparison chart of the predicted and experimental values ​​of the fire source power in an embodiment of the present invention. Detailed Implementation

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0039] Example 1

[0040] like Figure 1 As shown, this embodiment provides a method and system for locating the fire location and measuring the fire source power in an immersed tunnel. The method for locating the fire location and measuring the fire source power in an immersed tunnel includes the following steps:

[0041] The temperature distribution of the tunnel ceiling is measured using fiber optic grating array sensing technology, with the specific setup as follows:

[0042] Distributed heat-sensing gratings are installed 0.1m from the top of the immersed tunnel. The heat-sensing fire-detecting optical cables are arranged horizontally in a sinusoidal wave pattern within the cable tray, and are secured at the peak of the sine wave using fixing clamps. The specific installation method is as follows: Figures 2-3 As shown, flame-retardant plastic clamps are used for fixing.

[0043] Fiber optic grating sensors offer precise alarm positioning: the absolute accuracy of alarm points is high and is not limited by indicators such as temperature measurement accuracy and response time, making them a primary basis for temperature measurement.

[0044] To ensure the timeliness and accuracy of temperature detection in the tunnel, the detection area in the tunnel is divided into several fire compartments. Each compartment is 100m long, and 15 fiber Bragg grating sensors are evenly distributed, with a spacing of 6.6m between each sensor. A broadband optical signal emitted by a fiber Bragg grating temperature measurement host is used to scan the fiber Bragg grating sensor array. Each sensor on the fiber sensor array will reflect an optical signal with a different central wavelength. The fiber Bragg grating temperature measurement host demodulates the reflected optical signal to obtain its central wavelength value, and the environmental temperature value measured by each fiber Bragg grating sensor can be obtained by calculating according to its wavelength offset;

[0045] When a fire occurs, there is an abnormal temperature fluctuation at a certain position of the fiber Bragg grating sensor. Find the temperature detector with the largest temperature fluctuation among the fiber Bragg grating sensors set in the two temperature sensing cables, and record its temperature data, defined as T max ;

[0046] At the same time, a dual-wavelength fire detector is used to assist the fiber Bragg grating sensor to locate the fire source, assist in measuring the fire source power, and judge the size of the fire source;

[0047] The dual-wavelength flame detector compares the flashing frequencies of two wavelengths of the flame radiation light to determine whether a fire has occurred. The wavelength detector captures the β value of 1.0μm and the α value of 1.7μm. In the wavelength range of 1.0μm to 1.8μm, the curves of automobile lights, natural light, fluorescent lights, sodium lamps and other light sources show a downward trend, and the flame combustion curve shows an upward trend. Compare the β value and α value of the non-fire curve to get Pα - Pβ < 0, and compare the β value and α value of the fire curve to get Pq - PD > 0. Therefore, when the α value > β value, it is determined as a fire signal. Since the dual-wavelength detector captures the flame radiation light and is not affected by air flow, it can accurately report the specific location of the fire.

[0048] The fire source power Q is obtained in the signal processor, and the calculation formula is as follows;

[0049]

[0050] Where Q is the fire heat release rate, with the unit of kW; g is the acceleration of gravity, with the unit of m / s 2 ; T max is the maximum temperature measured by the fiber Bragg grating, with the unit of K; T ∞ is the environmental temperature in the tunnel, with the unit of K; H ef is the height from the fire source surface to the ceiling, with the unit of m; H is the tunnel elevation difference, with the unit of m.

[0051] The fire source power Q obtained in the signal processor is used for fire scale assessment, and it is reported in four levels: general fire, relatively large fire, major fire, and especially major fire.

[0052] Simultaneously, reports are made according to different fire scale levels. When the fire scale is a general fire or a relatively large fire, the fire alarm signal is uploaded to the immersed tunnel monitoring platform, which is responsible for centrally mobilizing fire rescue personnel for centralized rescue. When the fire scale is a major fire or an especially major fire, the fire alarm signal is directly uploaded to the local emergency management center.

[0053] This invention also provides a system for locating the fire location and determining the fire power in an immersed tunnel, comprising: a temperature detection module for real-time detection of the immersed tunnel temperature based on a temperature sensor; a fire source location module connected to the temperature detection module for locating the fire source location using a dual-wavelength fire source detector and an auxiliary temperature sensor when the temperature is abnormal; a temperature processing module connected to the fire source location module for obtaining the fire source power based on the highest temperature of the immersed tunnel using a fire source power calculation method; a fire alarm module connected to the temperature processing module for determining the fire scale level based on the fire source power; and a fire monitoring module connected to the fire alarm module for real-time monitoring of the fire source location, fire source power, and fire scale level.

[0054] The temperature detection module includes a detection area division unit and a sensor deployment unit. The detection area division unit is used to divide the detection area of ​​the immersed tunnel into several fire-prevention zones. The sensor deployment unit is used to preset the installation distance from the top of the tunnel in each fire-prevention zone, set up a cable tray at the preset installation distance, and arrange temperature sensors horizontally in a double-sided sine wave pattern along the length of the tunnel in the cable tray, and fix them at the peak of the sine wave using fixing clamps. The temperature sensors are fiber optic grating sensors.

[0055] As a specific embodiment, this embodiment uses a fiber Bragg grating temperature sensor, located at a distance of 0.01H from the top of the tunnel. ef Cable trays are installed at the distance, and the cable trays are arranged horizontally in a double-horizontal pattern along the longitudinal direction. Fixed clamps are used at the peaks of the positive and negative sine waves. Flame-retardant plastic clamps are used for fixing. The longitudinal direction indicates the length of the tunnel.

[0056] The signal processor is a fiber optic grating processor. The fire source power calculated in the signal processor can be transmitted to the monitoring platform and mobile terminal in real time, so that the tunnel fire monitoring platform and the staff in the tunnel can obtain accurate data as soon as possible. At the same time, dual-wavelength flame detectors are deployed in the tunnel to determine the location of the fire source and further improve the accuracy of the fire alarm.

[0057] The temperature processing module includes a temperature sorting unit and a power acquisition unit. The temperature sorting unit is used to sort the immersed tunnel temperatures obtained by the temperature sensors to obtain the highest temperature of the immersed tunnel. The power acquisition unit is used to obtain the corresponding fire source power based on the gravitational acceleration, the highest temperature of the immersed tunnel, the ambient temperature inside the tunnel, the height from the surface of the fire source to the ceiling, and the elevation difference of the tunnel.

[0058] As a specific embodiment, the output of the temperature sensor is connected to the signal processor, which can detect the temperature of the immersed tunnel roof in real time and send the measured temperature information to the signal processing terminal for processing; the fire source power calculation system is programmed in the signal processor to calculate the accurate fire source power by receiving the highest roof temperature transmitted by the fiber optic grating sensor. The calculation formula is as follows;

[0059]

[0060] Where Q is the fire heat release rate, in kW; and g is the acceleration due to gravity, in m / s². 2 ;T max The maximum temperature measured by the fiber Bragg grating, in K; T ∞ The ambient temperature inside the tunnel, in K; H ef H represents the height from the surface of the fire source to the ceiling, in meters; H represents the tunnel elevation difference, in meters.

[0061] The fire alarm module includes a classification unit and a signal alarm unit. The classification unit is used to classify the fire scale into four levels based on the fire source power: general fire, major fire, serious fire, and extremely serious fire. The signal alarm unit is used to upload the corresponding fire alarm signal to the immersed tunnel monitoring platform for processing when the fire scale is general fire or major fire, and to upload the corresponding fire alarm signal to the local emergency management center for processing when the fire scale is serious fire or extremely serious fire.

[0062] In a specific embodiment, the input terminal of the fire alarm controller is connected to the signal processor to receive the fire source power sent by the signal processor, evaluate the fire source power, and determine the fire scale level; the monitoring platform receives the fire alarm signal from the fire alarm controller, performs tunnel fire scale assessment, sets alarm thresholds, determines the fire scale level, and uploads it to the fire emergency rescue site for precise firefighting.

[0063] To demonstrate the accuracy of the fire source power prediction formula obtained above, the following verification was performed:

[0064] The verification data were obtained from FDS numerical simulation. The simulated immersed tunnel model had dimensions of 200m * 10m * 5m (length * width * height), which conforms to the size of the fire prevention zone of an immersed tunnel. In the simulation, the fire source was located at the center of the tunnel. The tunnel elevation differences were set to 1.8m, 3m, 4.2m, 6m, 7.2m, and 9m, corresponding to slopes of 3%, 5%, 7%, 10%, 12%, and 15%, respectively, to verify the slopes that might occur in the actual use of the immersed tunnel. The simulated fire source power was set to five gradients: 0.5MW, 1MW, 1.5MW, 2MW, 2.5MW, and 3MW, because fires in immersed tunnels are mostly caused by vehicle accidents, and the types of vehicles vary, resulting in fires of different sizes. The analysis of the highest temperature T on the tunnel ceiling in the numerical simulation was also performed. max The predicted fire source power is calculated using the fire source power prediction formula and compared with the actual fire source power value to obtain a comparison chart, as shown in Figure 4. It can be concluded that when the tunnel slope is between 3% and 15%, the above fire source power prediction formula can predict the fire source power relatively accurately.

[0065] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for locating the fire position and determining the fire source power in an immersed tunnel, characterized in that, Includes the following steps: Real-time monitoring of immersed tunnel temperature data based on temperature sensors; When the temperature is abnormal, the location of the fire source is located by using a dual-wavelength fire source detector and an auxiliary temperature sensor. At the same time, the corresponding fire source power is obtained by using the fire source power calculation method based on the highest temperature data in the immersed tunnel. The fire scale is assessed based on the fire source power, and a corresponding fire alarm signal is generated. The method for calculating the power of a fire source is shown in the following formula: Where Q is the fire heat release rate, g is the gravitational acceleration, and T is the acceleration due to gravity. max T represents the maximum temperature measured by the fiber Bragg grating sensor. ∞ H represents the ambient temperature inside the tunnel. ef H represents the height from the surface of the fire source to the ceiling, and H represents the tunnel elevation difference.

2. The method for locating the fire location and determining the fire source power in an immersed tunnel according to claim 1, characterized in that, The deployment process of the temperature sensor includes: dividing the detection area of ​​the immersed tunnel into several fire-prevention zones, setting a preset installation distance from the top of the tunnel in each fire-prevention zone, setting up a cable tray at the preset installation distance, arranging temperature sensors horizontally in a double-sided sine wave pattern along the tunnel length direction in the cable tray, and fixing them at the peak of the sine wave using fixing clamps; wherein, the temperature sensor is a fiber optic grating sensor.

3. The method for locating the fire position and determining the fire source power in an immersed tunnel according to claim 1, characterized in that, The scale of a fire includes at least a general fire, a relatively large fire, a major fire, and an especially major fire.

4. The method for locating the fire location and determining the fire source power in an immersed tunnel according to claim 1, characterized in that, The process of generating the corresponding fire alarm signal includes: when the fire is a general fire or a relatively large fire, the corresponding fire alarm signal is uploaded to the immersed tunnel monitoring platform for processing; when the fire is a major fire or an extremely major fire, the corresponding fire alarm signal is uploaded to the local emergency management center for processing.

5. A system for locating the fire location and determining the fire source power in an immersed tunnel, characterized in that, include: The temperature detection module is used to detect the temperature of the immersed tunnel in real time based on the temperature sensor. A fire source location module, connected to the temperature detection module, is used to locate the fire source position based on a dual-wavelength fire source detector and an auxiliary temperature sensor when the temperature is abnormal. A temperature processing module, connected to the fire source positioning module, is used to obtain the fire source power based on the highest temperature of the immersed tunnel using a fire source power calculation method. A fire alarm module, connected to the temperature processing module, is used to determine the fire scale level based on the fire source power. The fire monitoring module is connected to the fire alarm module and is used to monitor the location of the fire source, the power of the fire source, and the fire scale level in real time.

6. The system for locating the fire location and measuring the fire source power in an immersed tunnel according to claim 5, characterized in that, The temperature detection module includes a detection area division unit and a sensor deployment unit; The detection area division unit is used to divide the detection area of ​​the immersed tunnel into several fire protection zones; the sensor deployment unit is used to preset the installation distance from the top of the tunnel in each fire protection zone, set up a cable tray at the preset installation distance, arrange temperature sensors horizontally in a double sine wave pattern along the tunnel length direction in the cable tray, and fix them at the peak of the sine wave using a fixing clamp; wherein, the temperature sensor is a fiber optic grating sensor.

7. The system for locating the fire location and measuring the fire source power in an immersed tunnel according to claim 5, characterized in that, The temperature processing module includes a temperature sorting unit and a power acquisition unit; The temperature sorting unit is used to sort the immersed tunnel temperatures obtained by the temperature sensors to obtain the highest temperature of the immersed tunnel; the power acquisition unit is used to obtain the corresponding fire source power based on the gravitational acceleration, the highest temperature of the immersed tunnel, the ambient temperature inside the tunnel, the height from the surface of the fire source to the ceiling, and the elevation difference of the tunnel.

8. The system for locating the fire location and measuring the fire source power in an immersed tunnel according to claim 5, characterized in that, The fire alarm module includes a classification unit and a signal alarm unit; The classification unit is used to classify the fire scale into four levels based on the fire source power: general fire, major fire, serious fire, and extremely serious fire. The signal alarm unit is used to upload the corresponding fire alarm signal to the immersed tunnel monitoring platform for processing when the fire scale is general fire or major fire, and to upload the corresponding fire alarm signal to the local emergency management center for processing when the fire scale is serious fire or extremely serious fire.

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