Tunnel ventilation detection method

Abstract

This invention provides a tunnel ventilation detection method, belonging to the field of tunnel engineering. It includes: measuring the first wind speed and first air volume at the site using the upwind method or the sideways method according to a predetermined wind gauge movement route and at a first predetermined frequency; correcting and calculating the first wind speed and first air volume to obtain the actual second wind speed and second air volume at the site; detecting the tunnel gas content using a gas detection instrument at a second predetermined frequency to obtain the first gas content; calculating the tunnel's required air volume based on the first gas content, the number of people working simultaneously in the tunnel, the cross-sectional area of ​​the tunnel excavation face, the operation of diesel machinery in the tunnel, and the amount of explosives used; calculating the required air volume based on the required air volume and the second air volume; supplementing the required air volume with a third air volume; and completing the wind measurement. The purpose is to solve the problems of insufficient or excessive ventilation. The achieved technical effect is to avoid the occurrence of insufficient or excessive ventilation.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering technology, and in particular to a method for detecting tunnel ventilation. Background Technology

[0002] With the rapid development of transportation infrastructure construction, the number of tunnel projects is increasing daily. During tunnel construction and operation, ventilation conditions directly affect personnel safety, equipment operation, and construction efficiency, while methane concentration is a key factor affecting tunnel safety. Therefore, accurate and efficient tunnel ventilation detection methods are crucial. Traditional tunnel ventilation testing suffers from numerous problems. Some testing methods only obtain single data points such as wind speed or air volume, lacking a systematic testing process and failing to comprehensively consider the impact of complex environmental factors within the tunnel on ventilation effectiveness. Regarding wind speed measurement, without scientific measurement methods and frequencies, the accuracy and representativeness of the data are insufficient, leading to an inability to accurately reflect the actual ventilation conditions within the tunnel. For methane content detection, previous methods may have issues such as unreasonable testing frequency and low instrument precision, making it difficult to monitor methane concentration in a timely and accurate manner, thus failing to effectively prevent methane accidents. Furthermore, previous testing processes often neglected the scientific calculation of the tunnel's required air volume, failing to fully consider factors such as the number of workers inside the tunnel, the cross-sectional area of ​​the working face, the operation of diesel machinery, and the amount of explosives used. This resulted in a lack of scientific basis for the design and operation of the ventilation system, easily leading to insufficient or excessive ventilation, affecting construction safety and wasting energy. Summary of the Invention

[0003] This invention provides a tunnel ventilation detection method to address the shortcomings of existing tunnel ventilation detection methods, which are prone to insufficient or excessive ventilation, and to achieve a tunnel ventilation detection method that avoids both insufficient and excessive ventilation.

[0004] This invention provides a method for detecting tunnel ventilation, comprising: On-site wind measurement: Based on the set anemometer movement route and at the first set frequency, the first wind speed and first air volume are measured using the frontal or sideways method. Data correction: Correct the first wind speed and the first air volume to obtain the actual second wind speed and the second air volume on site; Tunnel gas detection: The first gas content is obtained by using a gas detection instrument to detect the gas content in the tunnel at the second set frequency. The required air volume for the tunnel is calculated based on the first gas content, the number of people working simultaneously inside the tunnel, the cross-sectional area of ​​the tunnel excavation face, the operation of diesel machinery inside the tunnel, and the amount of explosives used. The required air volume is then calculated based on the second air volume. Make-up air: Add a third air volume based on the air shortage. Wind measurement complete.

[0005] In addition, the tunnel ventilation detection method according to the present invention may also have the following additional technical features: In some embodiments of the present invention, the method for measuring the first wind speed and the first air volume at the site using the upwind method includes: The wind measurement operator stands in the middle of the tunnel, facing the direction of the wind flow, holding a wind gauge, and stretching his arm straight forward to use the wind gauge to measure the wind.

[0006] In some embodiments of the present invention, the method of measuring the first wind speed and the first wind volume at the site using the side-view method includes: the wind surveyor stands with his back to the tunnel wall, holds an anemometer, extends his arm in the direction perpendicular to the wind flow, and then uses the anemometer to perform wind measurement.

[0007] In some embodiments of the present invention, a method for obtaining a first gas content by detecting the gas content in a tunnel using a gas detection instrument includes: Gas concentrations were measured at various working faces inside the tunnel using a four-point or six-point method with gas detection instruments.

[0008] In some embodiments of the present invention, the set movement route of the wind gauge includes: Mobile anemometers using the standard method, four-line route method, six-line anemometer method, or grid-based fixed-point method.

[0009] In some embodiments of the present invention, the required ventilation volume of the tunnel is calculated based on the first gas content, the number of people working simultaneously inside the tunnel, the cross-sectional area of ​​the tunnel excavation face, the operation of diesel machinery inside the tunnel, and the amount of explosives used for blasting. The initial required ventilation volume for the tunnel is calculated based on the number of people working simultaneously inside the tunnel, and is set as follows: ; The second required ventilation volume for the tunnel is calculated based on the amount of explosive blasting, and is set as follows: ; The third required ventilation volume for the tunnel is calculated based on the cross-sectional area of ​​the tunnel excavation face and is set as follows: ; The fourth required ventilation volume for the tunnel is calculated based on the operation of diesel machinery inside the tunnel and is set as follows: ； The fifth required ventilation volume for the tunnel is calculated based on the first gas content and set as follows: ; Select , , , and The maximum setting is the required air volume of the tunnel, and it is denoted as... .

[0010] In some embodiments of the present invention, the first predetermined frequency includes: The wind speed in each tunnel is measured at least once a day.

[0011] In some embodiments of the present invention, the second predetermined frequency includes: The frequency of gas detection is set according to the gas concentration. When the gas concentration is below 0.1%, it is detected once per hour, and when the gas concentration is above 0.1%, it is detected once every 30 minutes.

[0012] In some embodiments of the present invention, the second predetermined frequency further includes: The gas concentration was checked once before charging the explosives, once before blasting, and once after blasting.

[0013] In some embodiments of the present invention, the use of a gas detection instrument to detect gas concentration at various working faces inside the tunnel using a four-point or six-point method includes: The four-point method was used to detect the gas concentration at the upper step inside the tunnel. The methane concentration was detected at six points along the entire cross-section of the tunnel.

[0014] In summary, this application includes the following beneficial technical effects: This ventilation detection method uses the upwind or sideways method for on-site wind measurement, combined with a set anemometer movement route and a first set frequency, to ensure the accuracy and real-time nature of wind speed and air volume data collection; the data correction step eliminates measurement errors, making the second wind speed and second air volume more consistent with actual working conditions. The tunnel gas detection at the second set frequency, combined with high-precision instruments, can promptly capture changes in gas concentration, effectively preventing gas accidents. In the air volume calculation stage, the required air volume is accurately calculated by comprehensively considering multiple factors such as the primary gas content, the number of workers, and the cross-sectional area. This calculated air volume is then compared with the actual secondary air volume to determine the insufficient air volume, providing a quantitative basis for optimizing the ventilation system. On-site records and ledger establishment ensure standardized data management, facilitating subsequent analysis and traceability. This entire method not only guarantees the safety of personnel and equipment during tunnel construction and operation, thus avoiding both insufficient and excessive ventilation, but also ensures construction safety. Attached Figure Description

[0015] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A flowchart illustrating a tunnel ventilation detection method according to some embodiments of the present invention is shown schematically.

[0016] Figure 2 A schematic diagram of the movement route of the segmented fixed-point method of the tunnel ventilation detection method according to some embodiments of the present invention is shown.

[0017] Figure 3 A schematic diagram illustrating the four-point method for detecting methane concentration in a tunnel ventilation detection method according to some embodiments of the present invention is shown.

[0018] Figure 4 A schematic diagram illustrating the six-point method for detecting methane concentration in a tunnel ventilation detection method according to some embodiments of the present invention is shown.

[0019] Figure label: 1. Wind measurement point, 2. Grid, 3. Gas measurement point. Detailed Implementation

[0020] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0021] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” used herein may also refer to the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a specific order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0022] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0023] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "upper," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure.

[0024] like Figures 1 to 4 As shown, according to an embodiment of the first aspect of the present invention, a tunnel ventilation detection method is proposed, comprising: On-site wind measurement: Based on the set anemometer movement route and at the first set frequency, the first wind speed and first air volume are measured using the frontal or sideways method. Data correction: Correct the first wind speed and the first air volume to obtain the actual second wind speed and the second air volume on site; Tunnel gas detection: The first gas content is obtained by using a gas detection instrument to detect the gas content in the tunnel at the second set frequency. The required air volume for the tunnel is calculated based on the first gas content, the number of people working simultaneously inside the tunnel, the cross-sectional area of ​​the tunnel excavation face, the operation of diesel machinery inside the tunnel, and the amount of explosives used. The required air volume is then calculated based on the second air volume. Make-up air: Add a third air volume based on the air shortage. Wind measurement complete.

[0025] In the above embodiments, it should be noted that a light interferometric methane detector and a portable methane detection alarm should be used for methane detection. When the strata are rich in harmful gases such as H2S, CO, and N2, a corresponding multi-gas detector should also be used to detect the methane concentration.

[0026] The technical effects achieved by the above embodiments are as follows: This ventilation detection method uses the windward or sideways method for on-site wind measurement, combined with a set anemometer movement route and a first set frequency, to ensure the accuracy and real-time nature of wind speed and air volume data collection; the data correction step eliminates measurement errors, making the second wind speed and second air volume more consistent with actual working conditions. The tunnel gas detection at the second set frequency, combined with high-precision instruments, can promptly capture changes in gas concentration, effectively preventing gas accidents. In the air volume calculation phase, the required air volume is accurately calculated by comprehensively considering multiple factors such as the primary gas content, the number of workers, and the cross-sectional area. This calculated air volume is then compared with the actual secondary air volume to determine the required air volume, providing a quantitative basis for optimizing the ventilation system. On-site records and ledger establishment ensure standardized data management, facilitating subsequent analysis and traceability. This entire method not only ensures the safety of personnel and equipment during tunnel construction and operation but also avoids energy waste through scientific regulation of the ventilation system, significantly improving the scientific rigor and efficiency of tunnel ventilation management.

[0027] Optional, such as Figure 1 As shown, the method for measuring the first wind speed and first wind volume at the site using the windward method includes: the wind surveyor stands in the middle of the tunnel, facing the direction of the wind flow, holds the anemometer, and uses the anemometer to measure the wind after extending his arm straight forward.

[0028] In the above optional embodiments, it should be noted that the anemometer's wind measurement work specifically includes: after the anemometer's impeller rotates normally, simultaneously turning on the stopwatch; allowing the anemometer to uniformly travel the entire cross-section along a set route within 1 minute; then simultaneously turning off the stopwatch and the anemometer, and reading the pointer indication. Because the person measuring the wind is standing in the middle of the tunnel, they obstruct the airflow, reducing the wind speed measured by the anemometer. To eliminate the influence of the human body on the airflow during wind measurement, the calculated actual wind speed must be multiplied by a correction factor. ( =1.14) is needed to obtain the actual wind speed.

[0029] Specifically, the formula for calculating the second air volume is as follows: First, calculate the wind speed indicated on the anemometer. Calculate according to the following formula: ; In the formula: t represents the reading on the anemometer dial; t represents the time of the wind measurement.

[0030] Then correct the wind speed, which means multiplying the calculated wind speed by a correction factor. The actual wind speed was calculated. The calculation formula is: ; In the formula: Represents actual wind speed; It represents the wind speed.

[0031] The formula for calculating the second air volume of the tunnel, which was then measured, is as follows: ; In the formula: The second air volume represents the tunnel's air volume; This represents the end face area of ​​the tunnel.

[0032] The advantages of the above-mentioned optional embodiments are as follows: In the upwind method, the anemometer stands directly in the middle of the tunnel facing the wind flow and extends its arm to measure the wind, allowing the anemometer to fully contact the mainstream wind speed, effectively reducing the interference of wind resistance from tunnel wall friction, and obtaining unobstructed, true wind speed and volume data. This method is standardized in operation and provides intuitive data, offering a precise benchmark for assessing the operating status of the ventilation system and calculating the required air volume, effectively ensuring the accuracy and reliability of tunnel ventilation testing results.

[0033] Optional, such as Figure 1 As shown, the method of measuring the first wind speed and first wind volume on site using the side-body method includes: the wind surveyor stands with his back to the tunnel wall, holds the anemometer, extends his arm in the direction perpendicular to the wind flow, and then uses the anemometer to measure the wind.

[0034] In the above optional embodiments, it should be noted that the wind measurement work of the wind meter specifically includes: after the wind meter's impeller rotates normally, the stopwatch of the timer is turned on at the same time, and the wind meter is made to travel evenly along the set route to the entire cross section within 1 minute. Then, the stopwatch and the wind meter are turned off at the same time, and the pointer indication is read.

[0035] Speed Calculate using the following formula: ; In the formula: t represents the reading on the anemometer dial; t represents the time of the wind measurement.

[0036] Then correct the wind speed, which means multiplying the calculated wind speed by a correction factor. The actual wind speed was calculated. The calculation formula is: ; In the formula: Represents actual wind speed. This represents the wind speed indicated on the anemometer. When the anemometer stands in the anemometer section of the tunnel, the tunnel wind speed will increase, requiring multiplication by a correction factor. This correction factor is: ; In the formula, Represents the correction factor; This represents the end face area of ​​the wind measurement point.

[0037] The formula for calculating the second air volume of the tunnel, which was then measured, is as follows: ; In the formula: This represents the second air volume in the tunnel. This represents the end face area of ​​the tunnel.

[0038] The advantages of the above optional embodiments are as follows: by using the side-facing method for wind measurement, the wind meter operator faces away from the tunnel wall and extends his arm vertically to measure the wind, which can effectively avoid the interference of the human body on the wind flow, reduce measurement errors, and thus ensure that the wind meter is in a relatively stable and unobstructed wind flow environment, ensuring that the first wind speed and first air volume data are true and reliable.

[0039] Optional, such as Figure 3 and Figure 4 As shown, the method for obtaining the first gas content by detecting the gas content in a tunnel using a gas detection instrument includes: Gas concentrations were measured at various working faces inside the tunnel using a four-point or six-point method with gas detection instruments.

[0040] In the above optional embodiments, it should be noted that the four-point method for detecting gas concentration includes: setting a gas measuring point 3 at the top of the tunnel, located at the highest point of the tunnel arch. Because gas density is less than air, it easily accumulates at high altitudes. This point can monitor the gas concentration at the arch and promptly detect gas accumulation at the top.

[0041] A gas measuring point 3 is set in the middle of the tunnel step, which serves as the wind measuring point 1. Gas may accumulate at the tunnel step due to factors such as water accumulation and geology. This gas measuring point 3 is used to monitor the gas concentration at the bottom.

[0042] A gas measuring point 3 is installed on each side of the tunnel step, located at the edge of each side of the tunnel step. This area is susceptible to construction disturbances and ventilation dead zones. Installing gas measuring points 3 can monitor the gas status of the side walls on both sides and prevent gas accumulation from causing danger.

[0043] The six-point method for detecting gas concentration includes setting a gas measuring point 3 at the top of the tunnel, located at the highest point of the tunnel arch. Since gas density is lower than air, it tends to accumulate upwards inside the tunnel. The arch is an area where gas easily accumulates. This gas measuring point 3 can capture changes in the gas concentration at the top in a timely manner and determine whether there is excessive gas accumulation.

[0044] A gas measuring point 3 is set at the bottom center of the tunnel, which is located at the exact center of the bottom of the tunnel and serves as the wind measuring point 1. Due to factors such as geological conditions and construction water accumulation, there may be a risk of gas accumulation at the bottom of the tunnel. This gas measuring point 3 is used to monitor the gas concentration at the bottom and ensure the safety of operations at the bottom.

[0045] A gas measuring point 3 is set on each side of the bottom edge of the tunnel. These areas are easily affected by construction equipment and vehicle operation, and the ventilation conditions may be complex and changeable. Setting up gas measuring points 3 can effectively monitor the gas concentration at the bottom of the sidewall and prevent gas accumulation from causing safety accidents.

[0046] A gas measuring point 3 is set on each side of the tunnel arch. The gas measuring point 1 is located at the midpoint of the height from the top of the arch to the bottom of the sidewall. The ventilation conditions at the arch are sometimes unstable, and the airflow may generate eddies, which can easily cause local gas accumulation. The gas measuring point 3 is used to monitor the gas concentration in this height area and to fully understand the gas distribution in the tunnel.

[0047] The advantages of the above-mentioned optional embodiments are as follows: This method allows for multi-point sampling at different locations on the working face, effectively avoiding the limitations of single-point detection, comprehensively covering areas where gas may accumulate, and ensuring that the detection data accurately reflects the gas concentration distribution on the working face. Whether it is the speed and efficiency of the four-point method or the precision and comprehensiveness of the six-point method, both can capture abnormal changes in gas concentration in a timely and accurate manner, providing a reliable basis for gas early warning and risk prevention and control, and significantly reducing the probability of accidents such as gas explosions.

[0048] Optional, such as Figure 2 As shown, the set movement routes for the anemometer include moving the anemometer using the standard method, the four-line route method, the six-line anemometer method, or the grid fixed-point method.

[0049] In the above optional embodiments, it should be noted that, considering the large cross-section of the tunnel, in order to accurately measure the wind speed, the moving line using the grid fixed-point method is adopted to measure the wind speed. During the measurement, the wind gauge should be located at the middle position of each grid as the wind measuring point 1.

[0050] Specific methods for measuring wind speed using a mobile anemometer along a fixed-point grid system include, for example: Figure 2 As shown, the tunnel cross-section is divided into 9 squares of 3×3. This is to measure wind speed in different areas, thereby obtaining a more accurate average wind speed.

[0051] The measurement steps include: First, select the middle position of grid 2 in the upper left corner of the tunnel cross-section as the starting point for wind measurement. Place the anemometer at this position with the windward side facing the direction of the airflow.

[0052] Then, starting from the middle of the top left square 2 as wind measurement point 1, move the anemometer horizontally to the right to the middle of the middle square 2 in the first row as wind measurement point 1. Then move it horizontally to the right again to the middle of the rightmost square 2 in the first row as wind measurement point 1. Next, move the anemometer vertically downwards to the middle of the rightmost square 2 in the second row as wind measurement point 1. Then move it horizontally to the left to the middle of the middle square 2 in the second row as wind measurement point 1. Then continue to move it horizontally to the left to the middle of the leftmost square 2 in the second row as wind measurement point 1. Then move it vertically downwards to the middle of the leftmost square 2 in the third row as wind measurement point 1. Then move it horizontally to the right to the middle of the middle square 2 in the third row as wind measurement point 1. Finally, move it horizontally to the right to the middle of the rightmost square 2 in the third row as wind measurement point 1. Throughout the entire movement, always keep the windward side of the anemometer facing the direction of the wind flow, and keep the movement speed as uniform and stable as possible to avoid sudden changes in speed affecting the measurement accuracy.

[0053] The advantages of the above-mentioned optional embodiments are as follows: By setting different route designs for the anemometer movement route using the standard method, four-line route method, six-line anemometer method, or grid-based fixed-point method, diverse tunnel cross-sectional shapes and sizes can be adapted. By uniformly covering gas measuring points 3 or using layered sampling, the non-uniform characteristics of wind speed distribution within the cross-section can be effectively captured, avoiding local data distortion caused by single-line measurement. For example, the six-line anemometer method accurately quantifies complex flow field structures through multi-line dense sampling; the grid-based fixed-point method is suitable for high-precision demand scenarios, eliminating blind spots through gridded point-by-point measurement. Standardized movement routes regulate manual operation procedures, reduce errors introduced by path arbitrariness, ensure the repeatability and comparability of measurement results, and provide high-precision data support for airflow correction and ventilation system evaluation.

[0054] Optional, such as Figure 1 As shown, the required ventilation volume for the tunnel is calculated based on the first gas content, the number of people working simultaneously inside the tunnel, the cross-sectional area of ​​the tunnel excavation face, the operation of diesel machinery inside the tunnel, and the amount of explosives used. The initial required ventilation volume for the tunnel is calculated based on the number of people working simultaneously inside the tunnel, and is set as follows: ; The second required ventilation volume for the tunnel is calculated based on the amount of explosive blasting, and is set as follows: ; The third required ventilation volume for the tunnel is calculated based on the cross-sectional area of ​​the tunnel excavation face and is set as follows: ; The fourth required ventilation volume for the tunnel is calculated based on the operation of diesel machinery inside the tunnel and is set as follows: ； The fifth required ventilation volume for the tunnel is calculated based on the first gas content and set as follows: ; Select , , , and The maximum setting is the required air volume of the tunnel, and it is denoted as... .

[0055] In the above optional embodiments, it should be noted that the principle for calculating the required air volume inside the tunnel includes: calculating based on the maximum number of people working simultaneously inside the tunnel, with 4 m³ / min of fresh air per person, to calculate... .

[0056] The required air volume is calculated based on the principle that harmful gases at the working face must be removed or diluted to an allowable concentration within 10 minutes of blasting. Each kilogram of explosives, when detonated, can produce the equivalent of 40 liters of carbon monoxide gas.

[0057] The minimum wind speed near the working face of a full-face excavation shall not be less than 0.15 m / s, and the minimum wind speed near the working face of a bench excavation shall not be less than 0.25 m / s. The maximum wind speed shall not exceed 6 m / s. Calculate the required air volume. .

[0058] When using diesel machinery inside the tunnel, follow the 4.0m... 3 The required air volume is calculated using / kW per minute. .

[0059] When gas erupts inside the tunnel, the required air volume is calculated based on the gas emission. .

[0060] The formula for calculating the first required air volume is: ; In the formula: This represents the amount of fresh air needed per person per minute inside the cave. This represents the maximum number of people working inside the cave at the same time. This represents the air volume reserve factor, which is set to 1.2.

[0061] The formula for calculating the second required air volume is: ; In the formula: 2.25 represents the empirical coefficient; This represents the amount of explosives used in a simultaneous blast; This represents the amount of harmful gases generated during an explosion. The ventilation time is represented by 15 minutes. This represents the cross-sectional area excavated in a single blasting operation; Represents the tunnel length or critical length; The coefficient representing the reduction in smoke concentration caused by water spraying; This represents the air leakage coefficient within the calculated length of the tunnel.

[0062] The formula for calculating the third required air volume is: ; In the formula: 60 represents the time conversion factor for converting wind speed units from seconds to minutes; Represents the maximum cross-sectional area; This represents the minimum permissible wind speed inside the cave.

[0063] The formula for calculating the fourth required air volume is: ; In the formula: Represents the power output of an internal combustion engine; This represents the air volume required per kilowatt of internal combustion engine when removing slag from the tunnel.

[0064] The formula for calculating the fifth required air volume is: In the formula: This represents the amount of gas emitted from the working face; This represents the permissible concentration of methane at the working face; The methane concentration represents the airflow supplied to the working face; Represents the coefficient of gas outburst unevenness. =1.5~2.0.

[0065] The formula for calculating the air shortage based on the required air volume and the second air volume is as follows: ; In the formula, This represents the required ventilation volume for the tunnel. This represents the second air volume in the tunnel. This represents the lack of ventilation in the tunnel.

[0066] The third air volume is added based on the missing air volume and recorded as follows: , Greater than or equal to That's all.

[0067] The beneficial effects of the above-mentioned optional embodiments are as follows: By independently calculating multi-dimensional parameters and taking the maximum value, the required air volume for tunnels is determined scientifically and accurately, effectively solving the problem of insufficient or excessive ventilation caused by single factors or human experience bias in traditional methods. Specifically, the first required air volume is calculated based on the number of workers to ensure the oxygen demand for personnel; the second required air volume is dynamically determined based on the amount of explosives used to dilute harmful gases, avoiding short-term concentration exceeding the standard; the third required air volume is set by multiplying the cross-sectional area by the minimum wind speed to ensure the suspended exhaust of dust; the fourth required air volume is combined with the diesel machinery power and the required air volume per unit power to specifically control the concentration of exhaust pollutants; the fifth required air volume is calculated based on the gas emission rate and the allowable concentration threshold to prevent the risk of gas accumulation. By parallel calculation of the five types of required air volumes and selecting the maximum value as the final value, the system covers core needs such as personnel safety, harmful gas dilution, dust control, machinery exhaust emissions, and gas prevention, avoiding risk omissions caused by unreasonable parameter coupling or weight allocation.

[0068] Optional, such as Figure 1 As shown, the first set frequency includes measuring the wind at least once a day in each tunnel.

[0069] The advantages of the above-mentioned optional embodiments are as follows: setting the frequency of wind measurement in each tunnel at least once a day as the first preset frequency enables timely monitoring of dynamic changes in ventilation within the tunnel. High-frequency detection allows for the rapid detection of abnormal fluctuations in wind speed and volume, timely investigation of potential hazards in the ventilation system, and provides strong protection for the safety of tunnel construction and operation. It also ensures the timeliness and continuity of ventilation data, facilitating real-time adjustments to ventilation strategies by management personnel and improving the scientific rigor and reliability of tunnel ventilation management.

[0070] Optional, such as Figure 1 As shown, the second set frequency includes setting the gas detection frequency based on the gas concentration: When the gas concentration is below 0.1%, it should be tested once per hour; When the gas concentration is above 0.1%, it should be tested every 30 minutes.

[0071] In the above optional embodiments, it should be noted that the gas concentration detection locations include: The various working faces inside the tunnel include: advanced drilling at the working face, excavation of the working face, initial support of the working face, excavation of the invert arch, construction of the invert arch concrete, installation of waterproof membrane, erection of formwork for secondary lining, pouring of concrete for secondary lining, and tunnel waterproofing treatment points.

[0072] Locations where gas may accumulate include the secondary lining trolley area, the widening strip, the upper part of the reserved cavern, the collapsed cavity, and locations with obvious depressions due to local over-excavation, all within 20 meters of the operating trolley and operating machinery in the airflow.

[0073] Locations inside the tunnel where fire sources may occur, such as near motors, electrical switches, and cable joints.

[0074] Locations where gas may seep or emerge abnormally, including geologically fractured zones, geologically changing zones, coal seam zones, sandstone, mudstone, and shale zones with developed fissures, and other locations with abnormal gas emergence.

[0075] Near the borehole opening during tunnel drilling.

[0076] Within a 20-meter radius of the site of electric welding operations, internal combustion engines, electrical switches, and motors inside the tunnel.

[0077] The airflow is within 20 meters of the blast site.

[0078] In the return airflow of tunnel ventilation and other areas with weak ventilation.

[0079] Passing through coal seams, fault fracture zones, fissure zones, and abnormal gas outburst points.

[0080] The advantages of the above optional embodiments are as follows: the detection frequency is dynamically set according to the gas concentration to achieve accurate monitoring. When the gas concentration is below 0.1%, it is detected once per hour, balancing efficiency and basic monitoring; when the concentration exceeds 0.1%, the detection frequency is increased to once every 30 minutes, which can quickly capture the concentration change trend, detect abnormal fluctuations in a timely manner, provide real-time data support for gas risk prevention and control, and effectively reduce the probability of gas accidents.

[0081] Optional, such as Figure 1 As shown, the second set frequency also includes: The gas concentration was checked once before charging the explosives, once before blasting, and once after blasting.

[0082] In the above optional embodiments, it should be noted that strict gas concentration detection should be carried out at the tunnel collapse site, over-excavation site, gas exploration hole, joint, crack, fissure development area, and geological fault site after blasting.

[0083] The second set frequency also includes continuous gas concentration detection during operations such as gas advance detection drilling, welding, cavity collapse and goaf treatment; continuous detection of gas concentration within a 20m range before and after the hot work point when welding or other hot work is carried out in the gas work area; and gas concentration detection before power is restored and the tunnel ventilation fan is started after the gas work area is shut down or the power is cut off.

[0084] The advantages of the above optional embodiments are as follows: pre-loading detection can avoid initial risks, pre-blasting detection can prevent dangerous operations, and post-blasting detection can promptly investigate abnormal concentrations caused by the explosion, thus comprehensively ensuring the safety of the blasting process and effectively preventing accidents such as gas explosions.

[0085] Optional, such as Figure 3 and Figure 4 As shown, the use of gas detection instruments to detect gas concentration at various working faces inside the tunnel using the four-point or six-point method includes: The four-point method was used to detect the gas concentration at the upper step inside the tunnel. The methane concentration was detected at six points along the entire cross-section of the tunnel.

[0086] In the above optional embodiments, it should be noted that the upper step refers to the upper half of the tunnel cross-section, usually the arch and the areas on both sides, which is the part that is excavated first; the full cross-section refers to the complete design outline of the tunnel, including the arch, sidewalls and bottom.

[0087] The advantages of the above-mentioned optional embodiments are as follows: Differentiated detection methods are adopted for different areas of the tunnel. The four-point method is used for rapid detection on the upper steps, which can efficiently grasp the gas status in key areas; the six-point method is used for detailed detection of the entire cross-section, which can comprehensively cover the entire cross-section and accurately capture the gas concentration distribution. The combination of these two methods ensures both detection efficiency and comprehensive and accurate data, providing a reliable basis for gas risk management and effectively guaranteeing tunnel construction safety.

[0088] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention 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 the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of detecting a tunnel ventilation, characterized in that, include: On-site wind measurement: Based on the set anemometer movement route and at the first set frequency, the first wind speed and first air volume are measured using the frontal or sideways method. Data correction: The first wind speed and the first air volume are corrected and calculated to obtain the actual second wind speed and the second air volume on site. Tunnel gas detection: The first gas content is obtained by using a gas detection instrument to detect the gas content in the tunnel at the second set frequency. The required air volume for the tunnel is calculated based on the first gas content, the number of people working simultaneously inside the tunnel, the cross-sectional area of ​​the tunnel excavation face, the operation of diesel machinery inside the tunnel, and the amount of explosives used for blasting. The required air volume and the second air volume are then used to calculate the air shortage. Make-up air: Add a third air volume based on the air shortage. Wind measurement complete.

2. The tunnel ventilation detection method of claim 1, wherein, Methods for measuring the initial wind speed and initial air volume at the site using the upwind method include: The wind measurement operator stands in the middle of the tunnel, facing the direction of the wind flow, holding a wind gauge, and stretching his arm straight forward to use the wind gauge to measure the wind.

3. The method of claim 1, wherein, The method of measuring the first wind speed and first wind volume on site using the side-view method includes: the anemometer stands with his back to the tunnel wall, holds an anemometer, extends his arm in the direction perpendicular to the airflow, and then uses the anemometer to measure the wind.

4. The method of tunnel ventilation detection according to any one of claims 1-3, characterized in that, The method for obtaining the first gas content by detecting the gas content in a tunnel using a gas detection instrument includes: Gas concentrations were measured at various working faces inside the tunnel using a four-point or six-point method with gas detection instruments.

5. The method of claim 1, wherein, The set movement path of the wind vane includes: Mobile anemometers using the standard method, four-line route method, six-line anemometer method, or grid-based fixed-point method.

6. The method of claim 1, wherein, The calculation of the tunnel's required ventilation volume based on the first gas content, the number of people working simultaneously inside the tunnel, the cross-sectional area of ​​the tunnel excavation face, the operation of diesel machinery inside the tunnel, and the amount of explosives used includes: According to the number of persons working in the tunnel hole at the same time, the first air requirement of the tunnel is calculated, and is set as ; The second required ventilation volume for the tunnel is calculated based on the amount of explosive blasting, and is set as follows: ; The third required ventilation volume for the tunnel is calculated based on the cross-sectional area of ​​the tunnel excavation face and is set as follows: ; The fourth required ventilation volume for the tunnel is calculated based on the operation of diesel machinery inside the tunnel and is set as follows: ； The fifth required ventilation volume for the tunnel is calculated based on the first gas content and set as follows: ; Select , , , and The maximum setting is the required air volume of the tunnel, and it is denoted as... .

7. The tunnel ventilation detection method according to claim 5, characterized in that, The first set frequency includes: The wind speed in each tunnel is measured at least once a day.

8. The tunnel ventilation detection method according to claim 1, characterized in that, The second set frequency includes: The frequency of gas detection is set according to the gas concentration: once per hour when the gas concentration is below 0.1%, and once every 30 minutes when the gas concentration is above 0.1%.

9. The tunnel ventilation detection method according to claim 8, characterized in that, The second set frequency also includes: The gas concentration was checked once before charging the explosives, once before blasting, and once after blasting.

10. The tunnel ventilation detection method according to claim 4, characterized in that, Using gas detection instruments, the gas concentration at each working face inside the tunnel is measured using either the four-point or six-point method, including: The gas concentration was detected at the four-point method at the upper step inside the tunnel. The gas concentration was detected at six points along the entire cross-section of the tunnel.

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