Automatic ventilation control method and system in construction tunnel

Abstract

The invention relates to the technical field of data processing, and provides an automatic ventilation control method and system in a construction tunnel, and the method comprises the steps: dividing the construction tunnel into a plurality of ventilation sections, and obtaining the harmful gas concentration, temperature, noise intensity and dust concentration of each ventilation section; after the harmful gas concentrations and the dust concentrations of all the ventilation sections are normalized, the weights of the harmful gas concentrations and the dust concentrations are calculated through an entropy weight method, and the comprehensive safety indexes of all the ventilation sections are calculated through a TOPSIS algorithm; and for each ventilation section, calculating the ratio of the comprehensive safety index to a preset threshold value to obtain an over-standard rate, calculating the power of an air draft fan in combination with the temperature, noise intensity, tunnel length, tunnel section size and distance from the tunnel exit of the ventilation section, and determining the opening degree of the ventilation opening according to the power of the air draft fan. And the automation and intelligence level of tunnel ventilation control is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of tunnel construction, and particularly relates to a method and system for automatically controlling ventilation in a construction tunnel. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] With the exploitation of underground mineral resources and the continuous construction of underground traffic engineering, tunnel excavation is increasing, and various dangers often occur in the process of tunnel excavation. It is necessary to take necessary tunnel construction danger prevention measures.

[0004] Drilling and blasting method is always the first choice for mountain tunnel excavation because of its strong adaptability to rock geological conditions, low excavation cost, and the advantage of being suitable for hard rock chamber construction. However, the high concentration of smoke and dust generated after blasting has a great harm to the health and safety of construction personnel. Moreover, harmful gases such as gas, carbon monoxide and ammonia may penetrate during the excavation of mountain surrounding rock. These harmful gases often occur in relatively closed structures in coal measures, and may also occur in non-coal strata. Harmful gases are often encountered in tunnels that penetrate coal seams, and a few are due to the proximity of coal seams and the geological structure that facilitates gas penetration or transmission.

[0005] Harmful gases in tunnel engineering usually refer to gas, methane (CH4), carbon dioxide (CO2), hydrogen sulfide (H2S) and radon, etc. These harmful gases not only harm human health, but also are flammable gases that often suddenly spew out, causing catastrophic damage, threatening the health of construction personnel and delaying the normal progress of the project.

[0006] Existing gas detection technology cannot guarantee the real-time and comprehensiveness of data, cannot accurately quantify the detection of tunnel environmental quality, and cannot provide solutions to emergency situations. Long-term construction work in tunnels with substandard environmental quality is not conducive to the safety of the project and the health of the construction personnel. How to detect the environmental quality in real time, safely and effectively ventilate and exhaust, and timely remind the construction personnel of the environmental quality in the tunnel is a technical problem that needs to be solved. SUMMARY

[0007] To solve the technical problems in the background art, the present application provides a construction tunnel automatic ventilation control method and system, based on the ratio of the comprehensive safety index and the preset threshold value, the multi-dimensional parameters of the temperature, noise, space size and distance from the outlet of the ventilation section are linked, the fan power is calculated, and the opening degree of the ventilation port is further determined according to the power, which not only avoids the deviation of subjective experience regulation, but also realizes differentiated ventilation according to the actual environment and safety demand of different ventilation sections, reduces energy waste while ensuring construction safety, and improves the automation and intelligence level of tunnel ventilation control.

[0008] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: The first aspect of the present application provides a construction tunnel automatic ventilation control method, which comprises: The construction tunnel is divided into several ventilation sections, and the harmful gas concentration, temperature, noise intensity and dust concentration of each ventilation section are obtained; After normalizing the harmful gas concentration and dust concentration of all the ventilation sections, the weight of each harmful gas concentration and dust concentration is calculated by entropy weight method, and the comprehensive safety index of each ventilation section is calculated by TOPSIS algorithm; For each ventilation section, the ratio of the comprehensive safety index to the preset threshold value is calculated to obtain the over-standard rate, the power of the exhaust fan is calculated in combination with the temperature, noise intensity, tunnel length, tunnel cross-sectional size and distance from the tunnel outlet, and the opening degree of the ventilation port is determined according to the power of the exhaust fan.

[0009] Further, the power of the exhaust fan is: ; Wherein, P i is the power of the small exhaust fan of the i th ventilation section; P0 represents the basic power coefficient; S i is the average cross-sectional area of the i th ventilation section; L i represents the actual length of the i th ventilation section; D i is the distance from the midpoint of the i th ventilation section to the tunnel outlet; v n,i is the natural wind speed corresponding to the i th ventilation section at the tunnel outlet; ΔT i is the temperature difference between the i th ventilation section and the tunnel outlet; α is the correction coefficient of temperature on air density; N i is the actual noise value of the i th ventilation section; N 0,i is the noise reference threshold value of the i th ventilation section; k1, k2 and k3 are weights.

[0010] Further, the harmful gas includes carbon monoxide, carbon dioxide, hydrogen sulfide, ammonia and gas.

[0011] Further, two air supply ducts are symmetrically arranged in the construction tunnel, each air supply duct penetrates the whole construction tunnel, and an air supply fan is arranged at each end of the air supply duct, and the outlet of the air supply fan is connected with the air supply duct, for supplying air outside the construction tunnel into the air supply duct.

[0012] Further, an air vent is arranged in each ventilation section of the air supply duct, and the amount of air in the air supply duct entering the construction tunnel is controlled by controlling the opening degree of the air vent.

[0013] Further, two air exhaust ducts are symmetrically arranged in the construction tunnel, each air exhaust duct penetrates the whole construction tunnel, and an air exhaust fan is arranged in each ventilation section, and the outlet of the air exhaust fan is connected with the air exhaust duct, for supplying air in the construction tunnel into the air exhaust duct, so as to be discharged out of the construction tunnel through the two ends of the air exhaust duct.

[0014] Further, when the comprehensive safety index exceeds the set value, it is judged whether the harmful gas concentration, temperature, noise intensity and dust concentration exceed the basic threshold value, so as to control the alarm to send a warning signal.

[0015] The second aspect of the present application provides an automatic ventilation control system in a construction tunnel, which comprises: a data acquisition module configured to divide the construction tunnel into a plurality of ventilation sections, and acquire the harmful gas concentration, temperature, noise intensity and dust concentration of each ventilation section; an index calculation module configured to normalize the harmful gas concentration and dust concentration of all the ventilation sections, calculate the weight of each harmful gas concentration and dust concentration by entropy weight method, and calculate the comprehensive safety index of each ventilation section by TOPSIS algorithm; a ventilation control module configured to calculate the ratio of the comprehensive safety index to the preset threshold value for each ventilation section, to obtain an over-standard rate, calculate the power of the air exhaust fan in combination with the temperature, noise intensity, tunnel length, tunnel cross-sectional size and distance from the tunnel exit of the ventilation section, and determine the opening degree of the air vent according to the power of the air exhaust fan.

[0016] The third aspect of the present application provides a computer readable storage medium having a computer program stored thereon, the program being executed by a processor to implement the steps of the automatic ventilation control method in a construction tunnel as described above.

[0017] The fourth aspect of the present application provides a computer device comprising a computer readable storage medium, a processor and a computer program stored on the computer readable storage medium and executable on the processor, and the processor implements the steps of the automatic ventilation control method in a construction tunnel as described above when executing the program.

[0018] Compared with the prior art, the application has the beneficial effects that: The application provides a construction tunnel automatic ventilation control method, which is based on the ratio of a comprehensive safety index to a preset threshold value, links multiple-dimensional parameters such as the temperature, noise, spatial size and distance from an exit of a ventilation section, calculates the power of a fan, and further associates the power to determine the opening degree of a ventilation opening, so as to avoid the deviation of subjective experience regulation, realize differentiated ventilation according to the actual environment and safety requirements of different ventilation sections, reduce energy waste while ensuring construction safety, and improve the automation and intelligent level of tunnel ventilation control.

[0019] The application provides a construction tunnel automatic ventilation control method, which directly associates safety risks through an exceeding rate, combines the sectional area and length of a ventilation section, ensures that a "high-risk and large-space ventilation section" obtains sufficient power, avoids safety hazards caused by insufficient ventilation, and realizes precise matching of "the higher the risk, the stronger the protection".

[0020] The application provides a construction tunnel automatic ventilation control method, which dynamically adapts to the environmental characteristics of different ventilation sections through parameters such as natural wind speed, distance from an exit, noise and temperature difference, and finally realizes that the more unfavorable the environment (the weaker the natural ventilation, the larger the noise and the greater the temperature difference), the more adaptive the power, and avoids insufficient or wasted power. DETAILED DESCRIPTION

[0021] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, and are incorporated in and constitute a part of this application. The embodiments of these drawings illustrate the preferred embodiments of the application and, together with the description, serve to explain the principles of the application.

[0022] Figure 1 is a flow chart of a construction tunnel automatic ventilation control method according to the first embodiment of the application; Figure 2 is a connection diagram of hardware involved in the construction tunnel automatic ventilation control method according to the first embodiment of the application; Figure 3 is a schematic diagram of an environmental quality detection device according to the first embodiment of the application; Figure 4 is a schematic diagram of a tunnel according to the first embodiment of the application; Figure 5 is a schematic diagram of a motor control circuit according to the first embodiment of the application; Figure 6 is a schematic diagram of an air extraction duct according to the first embodiment of the application; Figure 7 is a structural schematic diagram of a computer device according to the fourth embodiment of the application. DETAILED DESCRIPTION

[0023] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application.

[0024] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0025] Embodiment one The embodiment provides a construction tunnel automatic ventilation control method.

[0026] The construction tunnel automatic ventilation control method provided by the embodiment comprises the following steps as shown in the figure: Figure 1 Step 1, arranging an environment detection device, a signal converter, a central processor, a wireless transmission unit, a supply air duct, an exhaust air duct, and an exhaust fan in the construction tunnel.

[0027] The construction tunnel is divided into several ventilation sections (for example, every 50 meters is a ventilation section).

[0028] As shown in the figure, the environment detection device comprises a shell and a gas detection sensor, a dust detection sensor, a temperature detection sensor, and a noise detection sensor arranged on the shell, and an alarm. Figure 3 The shell of the environment quality detection device is provided with a screw hole, and the environment quality detection device is hung on the tunnel side wall through cooperation with a bolt. One environment quality detection device is arranged in each ventilation section in the construction tunnel.

[0029] The arrangement position of the environment quality detection device in each ventilation section can be based on computational fluid dynamics simulation to simulate the airflow distribution in the tunnel, identify the pollutant retention area (for example, the corner, the low wind speed area), and deploy the sensor in the retention area, the construction machinery concentration area, and the personnel concentration area to ensure that the detection covers no blind area.

[0030] One signal converter, one central processor, and one wireless transmission unit are arranged in the construction tunnel.

[0031] Figure 4 As shown in the figure, two supply air ducts are symmetrically arranged in the construction tunnel, and each supply air duct penetrates through the entire construction tunnel. One large exhaust fan (referred to as a supply air fan) (10KW) is arranged at the two ends of the supply air duct. An air outlet is connected with the supply air duct and is used for sending air outside the construction tunnel into the supply air duct. Figure 6 ​​As shown, the air supply duct is provided with an electric ventilation port in each ventilation section. By controlling the switch of the electric ventilation port, the air in the air supply duct enters the construction tunnel. By controlling the opening degree of the electric ventilation port, the amount of air in the air supply duct entering the construction tunnel is controlled.

[0032] As shown, Figure 4 The construction tunnel is symmetrically provided with two air exhaust ducts, each of which penetrates the entire construction tunnel. A small air exhaust fan (1KW) is arranged in each ventilation section, and the air outlet is connected with the air exhaust duct, which is used to send the air in the construction tunnel into the air exhaust duct, so that the air is discharged from the construction tunnel through the two ends of the air exhaust duct.

[0033] As shown, Figure 5 The large air exhaust fan, the small air exhaust fan, the switch of the electric ventilation port and the motor are connected with the central processor to control the switch communication and the power of the motor.

[0034] Step 2, environmental detection.

[0035] As shown, Figure 2 and Figure 3 The environmental detection device can accurately monitor various data parameters affecting the safety of the tunnel environment in real time, including harmful gas concentration (such as carbon monoxide, carbon dioxide, hydrogen sulfide, ammonia, gas), temperature, noise intensity and dust concentration.

[0036] Among them, the gas detection sensor is used to detect the content of harmful gases in the tunnel: carbon monoxide, carbon dioxide, hydrogen sulfide, ammonia, gas; the noise detection sensor detects the intensity of the noise generated during the construction process; the temperature sensor realizes the detection of the construction environment temperature in the tunnel; the dust concentration detection sensor realizes the detection of the dust concentration generated during the construction in the tunnel, and completes the real-time detection of the construction environment in the tunnel.

[0037] Step 2, wireless transmission.

[0038] The analog signal collected by the sensor is converted into a digital signal that can be recognized by the computer through the signal converter, and uploaded to the central processor; the central processor uploads the digital signal to the background control center through the WiFi wireless transmission unit, and completes the real-time reporting of data. Not only improves the efficiency and stability of data transmission, but also enables construction personnel and management personnel to check the environmental conditions in the tunnel through the background control center at any time and any place, timely grasp the trend of construction environment change, and ensure the comprehensive control of construction environment safety.

[0039] Step 3, background processing. The tunnel detection data is sent to the work computer in the background control center, and the work computer records and analyzes the data to determine whether the tunnel environment safety meets the standards.

[0040] Step 301, the harmful gas concentration and dust concentration of all detection points are subjected to range method normalization processing to eliminate dimensional differences: ; wherein, assuming that there are m detection parameters and n detection points, x ij represents the detection value of the jth detection parameter (j = 1, 2,..., m) of the ith detection point (i = 1, 2,..., n); y ij represents the value of the jth detection parameter of the ith detection point after normalization (y ij ∈ [0, 1]); max j represents the original maximum value of the jth parameter in all detection points (max j = max(x 1j , x 2j ,..., x nj )); min j represents the original minimum value of the jth parameter in all detection points (min 1j = min(x 2j , x nj ,..., x j )); one detection point corresponds to one ventilation section.

[0041] Step 302, based on the entropy weight method, the weight w j of each detection parameter (each harmful gas concentration and dust concentration) is calculated: ; wherein, the difference coefficient g j = 1-e i , the entropy value , and the parameter relative proportion .

[0042] Step 303, based on the weight of each detection parameter, the comprehensive safety index (C ij value) of each detection point is calculated by the TOPSIS algorithm: ; wherein, , , negative ideal solution (j = 1, 2,..., m), positive ideal solution (j = 1, 2,..., m), Z j = w ij ·y .

[0043] As shown above, the lower the concentration (harmful gas, dust) → the greater the normalized value (y ij ) → the greater the weighted value (Zij ) The closer to the optimal state -> C i The greater the value (the higher the safety level).

[0044] The weight is calculated based on the "information entropy" of each detection parameter: the smaller the entropy value, the greater the fluctuation of the parameter value (i.e., the greater the difference between different detection points), and the more information it contains to distinguish the safety state, so it is given a higher weight. This process relies entirely on the distribution characteristics of the data itself, rather than human experience, and can objectively reflect the actual impact of each parameter on safety evaluation (for example, if the difference in "harmful gas concentration" between different detection points is much greater than the "temperature", its weight will automatically be higher), avoiding the deviation caused by subjective weighting (such as expert scoring), and improving the scientificity and credibility of the weight.

[0045] Step 4, based on the comprehensive safety index of each detection point, control the opening degree of the ventilation port and the power of the small exhaust fan in each ventilation section.

[0046] For each ventilation section, based on the comprehensive safety index, calculate the over-standard rate η i , η i is the ratio of the comprehensive safety index of the ventilation section to the preset threshold; For each ventilation section, based on the over-standard rate, temperature, noise intensity, and distance from the tunnel exit, calculate the power of the small exhaust fan: ; where P i is the power of the small exhaust fan in the i-th ventilation section; P0 represents the basic power coefficient, with a unit of kW, which is preset according to the type of tunnel and provides a basis for power calculation for the i-th ventilation section; S i is the average cross-sectional area of the i-th ventilation section, with a unit of m 2 , reflecting the size of the space section that needs to be covered by ventilation in this ventilation section; L i represents the actual length of the i-th ventilation section, with a unit of m, embodying the length of the interval that needs to be independently ventilated in this ventilation section; D i is the distance from the midpoint of the i-th ventilation section to the tunnel exit, with a unit of m, the farther the distance, the worse the natural ventilation conditions of this ventilation section; v n,i is the natural wind speed at the tunnel exit corresponding to the i-th ventilation section, with a unit of m / s, , v n,实测 is the average of the two measured wind speeds at the tunnel exit, and β is the wind speed attenuation coefficient, which is determined according to the type of tunnel (such as mine tunnel, β takes 0.002-0.003, highway tunnel takes 0.001-0.002), reflecting the speed of wind speed attenuation with distance, and the wind speed size affects the compensation ability of natural ventilation to mechanical ventilation in this ventilation section; ΔT iTemperature difference between the i th ventilation section and the tunnel outlet, unit: ℃, the temperature difference affects the air convection resistance of the ventilation section; α is the correction coefficient of temperature on air density; N i Actual noise value of the i th ventilation section, unit: dB(A), reflecting the environmental noise of the ventilation section; N 0,i Noise reference threshold value of the i th ventilation section, unit: dB(A), usually 85 dB(A), as the judgment standard of whether the ventilation section needs to compensate power due to noise; k1, k2, k3 are weights, unitless, which can be adjusted according to the actual scene of the ventilation section to adjust the proportion of influence of each factor.

[0047] The embodiment dynamically adjusts the power of the ventilation section according to the over-standard rate η i directly related to the safety risk, combined with the cross-sectional area S i and the length L i of the ventilation section, to ensure that the “high-risk and large-space ventilation section” obtains sufficient power, avoids safety hazards caused by insufficient ventilation, and realizes the precise matching of “the higher the risk, the stronger the protection”.

[0048] The embodiment dynamically adapts to the environmental characteristics of different ventilation sections through natural wind speed, distance from the outlet, noise, temperature difference, etc., and finally realizes that the more unfavorable the environment (weak natural ventilation, high noise, large temperature difference), the more adaptive the power, avoiding insufficient or waste of power.

[0049] Among them, the opening degree of the ventilation port and the power of the small exhaust fan are proportional, for example, k4P i , k4 is a coefficient.

[0050] The embodiment adopts a gradient air supply mode for the air supply duct, gradually reduces the air supply amount from the tunnel entrance to the deep place, gradually increases the air extraction amount for the air extraction duct, forms a gradient pressure difference, speeds up the discharge of pollutants, and only opens the electric ventilation port in the area where the pollutants exceed the standard, thereby reducing the invalid energy consumption.

[0051] Step 5, when the harmful gas content in the tunnel is high or the air quality is poor, and it cannot meet the standard for a long time, that is, the C i value exceeds the threshold value, it is judged whether each detection parameter exceeds the basic threshold value, and the alarm is controlled to issue a warning signal to remind the construction personnel that the construction environment is unsafe and to evacuate the tunnel in time.

[0052] The gas concentration reference threshold value in the coal seam tunnel is set to 0.8% (lower than the national standard of 1.0%), the dust concentration reference threshold value is set to 4 mg / m 3 (lower than the national standard of 6 mg / m 3 ), the carbon monoxide reference threshold value in the non-coal seam tunnel is set to 20 ppm (national standard 24 ppm), and the hydrogen sulfide reference threshold value is set to 6 ppm (national standard 10 ppm); the dust concentration reference threshold value in the blasting stage is dynamically lowered to 2 mg / m 3, the noise reference threshold value is set to 90dB, the temperature reference threshold value in the support stage is set to 32℃ (higher than the conventional 28℃), and when the real-time detection value exceeds 80% of the reference threshold value for 3 times in succession, the reference threshold value is automatically triggered to be tightened (decreased by 5%~10%), and if the standard is not exceeded for 12 hours, the initial reference threshold value is restored.

[0053] The embodiment can monitor a plurality of key parameters in the tunnel construction environment in real time and accurately through the integrated environmental detection device, including harmful gas concentration (such as carbon monoxide, carbon dioxide, gas, hydrogen sulfide), temperature, noise intensity and dust concentration, and ensures comprehensive control of the safety of the construction environment.

[0054] The embodiment realizes instant reporting of detection data to the background control center by using a wireless transmission system, which not only improves the efficiency and stability of data transmission, but also enables construction personnel and management personnel to check the environmental conditions in the tunnel through a PC terminal or a mobile terminal at any time and any place, and timely master the change trend of the construction environment.

[0055] The embodiment can automatically adjust the ventilation opening setting of the corresponding area, increase the fan wind power, effectively remove harmful gases and dust, and maintain the safety and health of the construction environment when the environmental detection data exceeds the allowable range of construction, which significantly improves the construction safety management level and reduces the lag and inaccuracy of human intervention.

[0056] The early warning function of the embodiment can automatically send an early warning signal when the environmental quality in the tunnel does not meet the standard for a long time, reminding the construction personnel to evacuate in time, effectively avoiding the occurrence of safety accidents, and the early warning mechanism provides a valuable time window for emergency response and enhances the safety protection capability of the construction site.

[0057] The data visualization of the embodiment enables the environmental detection data to be displayed in an intuitive and easy-to-understand chart form, which is convenient for management personnel to analyze data and make management decisions. At the same time, the identification and recording function of the data by the background control center also provides reliable data support for subsequent environmental quality evaluation, safety audit and other work.

[0058] Embodiment Two The automatic ventilation control system for a construction tunnel provided in the embodiment comprises: The data acquisition module is configured to divide the construction tunnel into a plurality of ventilation sections, and acquire harmful gas concentration, temperature, noise intensity and dust concentration of each ventilation section. The index calculation module is configured to normalize the harmful gas concentration and dust concentration of all the ventilation sections, calculate the weight of each harmful gas concentration and dust concentration by the entropy weight method, and calculate the comprehensive safety index of each ventilation section by the TOPSIS algorithm. The ventilation control module is configured to: for each ventilation section, calculate a ratio of an integrated safety index to a preset threshold to obtain an over-standard rate, combine a temperature, a noise intensity, a tunnel length, a tunnel cross-section size, and a distance from a tunnel exit of the ventilation section to calculate a power of an exhaust fan, and determine an opening degree of a ventilation opening according to the power of the exhaust fan.

[0059] It should be noted that each module in the embodiment corresponds to each step in Embodiment One, and the specific implementation process is the same, which will not be repeated here.

[0060] Embodiment Three The embodiment provides a computer readable storage medium, which stores a computer program, and the program is executed by a processor to realize steps in the automatic ventilation control method for a construction tunnel.

[0061] Embodiment Four The embodiment provides a computer device, which comprises a computer readable storage medium 1003, a processor 1001, a communication interface 1002, and a computer program stored in the computer readable storage medium 1003 and capable of running on the processor 1001. Figure 7 As shown in the figure, the computer device comprises a computer readable storage medium 1003, a processor 1001, a communication interface 1002, and a computer program stored in the computer readable storage medium 1003 and capable of running on the processor 1001, wherein the processor 1001, the communication interface 1002, and the computer readable storage medium 1003 are connected through a bus or other means. The communication interface 1002 is used for receiving and sending data, and the processor 1001 realizes steps in the automatic ventilation control method for a construction tunnel when executing the program.

[0062] The above merely describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of automatically controlling ventilation in a construction tunnel, characterized in that, The method comprises the following steps: The construction tunnel is divided into several ventilation sections, and the harmful gas concentration, temperature, noise intensity and dust concentration of each ventilation section are obtained; After normalization of the harmful gas concentration and dust concentration of all the ventilation sections, the weight of each harmful gas concentration and dust concentration is calculated by entropy weight method, and the comprehensive safety index of each ventilation section is calculated by TOPSIS algorithm; For each ventilation section, the ratio of the comprehensive safety index to the preset threshold value is calculated to obtain the exceeding rate, and the power of the exhaust fan is calculated in combination with the temperature, noise intensity, tunnel length, tunnel cross-sectional size and distance from the tunnel outlet, and the opening degree of the ventilation port is determined according to the power of the exhaust fan.

2. A method of automatically controlling ventilation in a construction tunnel according to claim 1, characterized in that, The power of the exhaust fan is: ； wherein P i is the power of the small exhaust fan of the i-th ventilation section; P0 represents the basic power coefficient; S i is the average cross-sectional area of the i-th ventilation section; L i represents the actual length of the i-th ventilation section; D i is the distance from the midpoint of the i-th ventilation section to the tunnel outlet; v n,i is the natural wind speed corresponding to the i-th ventilation section at the tunnel outlet; ΔT i is the temperature difference between the i-th ventilation section and the tunnel outlet; α is the correction coefficient of temperature to air density; N i is the actual noise value of the i-th ventilation section; N 0,i is the noise reference threshold value of the i-th ventilation section; k1, k2, k3 are weights.

3. A method of automatically controlling ventilation in a construction tunnel according to claim 1, wherein The harmful gas includes carbon monoxide, carbon dioxide, hydrogen sulfide, ammonia and gas.

4. A method of automatically controlling ventilation in a construction tunnel according to claim 1, wherein Two air supply blowers are symmetrically arranged in the construction tunnel, each air supply blower penetrates through the entire construction tunnel, and an air supply fan is arranged at each end of the air supply blower, and the air outlet of the air supply fan is connected with the air supply blower for supplying air outside the construction tunnel into the air supply blower.

5. A method of automatically controlling ventilation in a construction tunnel according to claim 4, characterized in that, An air supply blower is arranged in each ventilation section, and the amount of air in the air supply blower entering the construction tunnel is controlled by controlling the opening degree of the ventilation port.

6. A method of automatically controlling ventilation in a construction tunnel according to claim 1, wherein Two air exhaust blowers are symmetrically arranged in the construction tunnel, each air exhaust blower penetrates through the entire construction tunnel, and an air exhaust fan is arranged in each ventilation section, and the air outlet of the air exhaust fan is connected with the air exhaust blower for supplying air in the construction tunnel into the air exhaust blower, so that the air is discharged from the construction tunnel through the two ends of the air exhaust blower.

7. A method of automatically controlling ventilation in a construction tunnel according to claim 1, wherein When the comprehensive safety index exceeds the set value, it is judged whether the harmful gas concentration, temperature, noise intensity and dust concentration exceed the basic threshold value to control the alarm to send a warning signal.

8. A system for automatically controlling ventilation in a construction tunnel, characterized in that The method comprises the following steps: The data acquisition module is configured to divide the construction tunnel into several ventilation sections, and obtain the harmful gas concentration, temperature, noise intensity and dust concentration of each ventilation section; The index calculation module is configured to, after normalization of the harmful gas concentration and dust concentration of all the ventilation sections, calculate the weight of each harmful gas concentration and dust concentration by entropy weight method, and calculate the comprehensive safety index of each ventilation section by TOPSIS algorithm; The ventilation control module is configured to, for each ventilation section, calculate the ratio of the comprehensive safety index to the preset threshold value to obtain the exceeding rate, and calculate the power of the exhaust fan in combination with the temperature, noise intensity, tunnel length, tunnel cross-sectional size and distance from the tunnel outlet, and determine the opening degree of the ventilation port according to the power of the exhaust fan.

9. A computer-readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to realize the steps in the automatic ventilation control method in the construction tunnel according to any one of claims 1-7.

10. A computer device, comprising a computer readable storage medium, a processor, and a computer program stored on the computer readable storage medium and executable on the processor, wherein, The processor executes the program to realize the steps in the automatic ventilation control method in the construction tunnel according to any one of claims 1-7.

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