Harmful gas risk prevention and control method for tunnel non-coal stratum

Abstract

The invention relates to the field of tunnel engineering construction risk prevention and control, in particular to a tunnel non-coal stratum harmful gas risk prevention and control method. Comprising the steps that S100, the geological structure of a tunnel non-coal stratum is detected in advance, and the type of harmful gas generated by the geological structure is analyzed; s200, according to the types of the harmful gases, classifying the risk grades of the harmful gases in the non-coal stratum of the tunnel, according to the surrounding rock and gas outlet state conditions, establishing a non-coal harmful gas disaster-causing risk judgment standard, and according to the non-coal harmful gas disaster-causing risk judgment standard, determining a risk position; s300, harmful gas monitoring points are arranged at the risk positions, and the concentration of harmful gas and the wind speed of the roadway are monitored in real time; and S400, executing prevention and control measures according to the monitoring data and the risk level. According to the method, the risk identification and prevention and control capability of geological disasters induced by harmful gas in the tunnel non-coal stratum is improved, and the construction safety is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of risk prevention and control in tunnel engineering construction, specifically a method for risk prevention and control of harmful gases in non-coal strata of tunnels. Background Technology

[0002] In tunnel construction, hazardous gases are often present when traversing non-coal strata, such as tunnel gas (CH4), carbon monoxide (CO), carbon dioxide (CO2), hydrogen sulfide (H2S), nitrogen dioxide (NO2), sulfur dioxide (SO2), ammonia (NH3), hydrogen (H2), and nitrogen (N2). These hazardous gases pose a threat to the safety of construction workers and the smooth progress of the project, and also have a significant impact on tunnel operation safety. Therefore, implementing hazardous gas risk control in non-coal strata is of great significance for ensuring the safety of tunnel construction in non-coal strata. Summary of the Invention

[0003] To address the limitations of existing identification methods for controlling the risk of harmful gases in non-coal strata of tunnels, which cannot effectively detect harmful gases in non-coal strata of tunnels and improve the identification and prevention of disaster risks, this invention provides a method for controlling the risk of harmful gases in non-coal strata of tunnels.

[0004] This invention adopts the following technical solution: a method for risk prevention and control of harmful gases in non-coal strata of tunnels, comprising: S100: Advanced exploration to determine the geological structure of non-coal strata in tunnels and analyze the types of harmful gases produced by the geological structure; S200: Classify the hazard level of hazardous gases in non-coal strata of tunnels according to the type of hazardous gases, establish a disaster risk identification standard for non-coal hazardous gases based on the surrounding rock and gas emission conditions, and determine the risky locations based on the disaster risk identification standard for non-coal hazardous gases. S300: Hazardous gas monitoring points are set up in high-risk locations to monitor the concentration of hazardous gases and wind speed in the tunnel in real time; S400: Implement prevention and control measures based on monitoring data and risk levels.

[0005] In some embodiments, the advance detection method in step S100 includes: Geological survey method, geophysical exploration method, advanced drilling method, advanced pilot tunnel method, and advanced borehole detection method.

[0006] In some embodiments, the types of harmful gases in step S100 include: Hydrogen sulfide, methane, carbon monoxide, sulfur dioxide, carbon dioxide, nitrogen oxides, ammonia, hydrogen, and nitrogen.

[0007] In some embodiments, the principle for classifying the hazard levels of harmful gases is as follows: For hydrogen sulfide, Extremely high hazard zone: Hydrogen sulfide content α ≥ 0.002%; High-risk area: Hydrogen sulfide content 0.0198% ≤ α < 0.0502%; Moderately hazardous area: Hydrogen sulfide content 0.00066% ≤ α < 0.0198%; Low-risk area: Hydrogen sulfide content 0.000000041% ≤ α < 0.00066%; For methane, Extremely high hazard zone: methane content 5% ≤ α < 16% or α ≥ 43%; High-risk area: methane content 16% ≤ α < 43%; Moderate hazard zone: Methane content 5% ≤ α < 16%; Low-risk area: methane content α < 0.5%; For carbon monoxide, Extremely high risk area: carbon monoxide content α ≥ 0.04%; High-risk area: Carbon monoxide content ≤ α < 0.0048%; Moderate hazard zone: Carbon monoxide content 0.0024% ≤ α < 0.0048%; Low-risk area: Carbon monoxide content 0.0009% ≤ α < 0.0024%; For sulfur dioxide, Extremely high hazard zone: Sulfur dioxide content α ≥ 0.05%; High-risk area: Sulfur dioxide content ≤ α < 0.002%; Moderately hazardous area: Sulfur dioxide content 0.0005% ≤ α < 0.002%; Low-risk area: Sulfur dioxide content 0.000002% ≤ α < 0.0005%; Regarding carbon dioxide, Extremely high risk area: carbon dioxide content α ≥ 6%; High-risk area: Carbon dioxide content 5% ≤ α < 6%; Moderate hazard zone: Carbon dioxide content 0.5% ≤ α < 5%; Low-risk area: Carbon dioxide content ≤ α < 0.5%; For nitrogen oxides, Extremely high hazard zone: Nitrogen oxide content α ≥ 0.025%; High-risk area: Nitrogen oxide content ≤ α < 0.025%; Moderately hazardous area: Nitrogen oxide content ≤ α < 0.00025%; Low-risk area: Nitrogen oxide content ≤ α < 0.0000034%; For ammonia, Extremely high risk area: ammonia content α ≥ 30%; High-risk area: Ammonia content ≤ α < 30%; Moderately hazardous area: Ammonia content 0.004% ≤ α < 0.05%; Low-risk area: Ammonia content 0.0000132% ≤ α < 0.004%; For hydrogen, Extremely high danger zone and highly dangerous zone: hydrogen content 5% ≤ α < 74%; For nitrogen, Extremely high risk area, high risk area and moderate risk area: 19.5%≤α<74%.

[0008] In some embodiments, the criteria for identifying the disaster risk caused by non-coal hazardous gases are as follows: Low risk: There are fractured anomalies and non-coal hazardous gases are briefly released. Brief release means the duration is less than 1 minute and the gas dissipates rapidly. Moderate risk: There are abnormal fractures and intermittent jetting of non-coal hazardous gases, with intermittent jetting lasting 1-5 minutes and accompanied by local accumulation; High risk: There are fractured anomalies and continuous emission of non-coal hazardous gases, with continuous emission lasting for ≥5 minutes and gas pressure <10kPa; Extremely high risk: There are abnormal fracture bodies and continuous emission of non-coal hazardous gases, with the continuous emission lasting for ≥5 minutes and the gas pressure ≥10kPa.

[0009] In some embodiments, in step S300, the monitoring points and their ranges meet the following requirements: 1) In the airflow and return airflow of the excavation face, in the airflow within 20m of the blasting site, and at the site of local collapse and roof fall; 2) In the airflow of the tunnel's main return air; 3) In the airflow within 10m before and after the local fan and electrical switches; 4) Within 20m of various work trolleys and machinery in the airflow; 5) In the airflow within 20m of the motor and its switch; 6) Areas where harmful gases easily accumulate, such as tunnels and chambers; Monitoring point layout: Five monitoring points are set up for each cross section, one at the top of the arch, one on each side of the arch waist, and one on each side wall shoulder 1.5~2.0m above the road shoulder; Under the condition of understanding the pattern, at least 3 monitoring points should be set for each cross section: one at the top of the arch, one on each side wall within 1.5 to 2.0m above the road shoulder, and the average value of the monitoring data of the cross section should be used to calculate the concentration of harmful gases.

[0010] In some embodiments, in step S300, when the non-coal hazardous gas disaster risk identification criteria are used... When the risk level is low, strengthen monitoring and surveillance. When the risk level is moderate, strengthen monitoring and surveillance, conduct deeper and more frequent targeted drilling, and collect gas samples for indoor gas composition analysis. When in a high-risk situation, strengthen monitoring and surveillance, conduct deeper and more frequent targeted drilling, collect gas samples for indoor gas composition analysis, and develop specific detection and ventilation plans; When the risk level is extremely high, strengthen monitoring and surveillance, conduct deeper and more frequent targeted drilling, collect gas samples for indoor gas composition analysis, and develop specific detection and ventilation plans.

[0011] In some embodiments, step S400 includes: S401: Ventilate during construction; S402: Conduct construction blasting; When the gas detection report contains methane, carbon monoxide, hydrogen sulfide, ammonia and hydrogen, sodium bicarbonate solution is used for the mud and water bag making while water pressure blasting is used. The dust suppression spraying in the tunnel is a weak alkaline NaHCO3 solution to reduce the concentration of hydrogen sulfide gas. S403: Structural protection, hazardous gas structural protection sections are protected by different levels of reinforcement, seepage prevention materials and explosion-proof electrical equipment, similar to gas-prone sections; S404: To seal and exhaust harmful gases; S405: Take personal protective measures.

[0012] In some embodiments, if real-time monitoring shows that the gas concentration is in an extremely dangerous zone, then S404 or S405 is executed first.

[0013] In some embodiments, in step S401, based on the data monitored by the hazardous gas monitoring points in step S300, the hazardous gas hazard level of the non-coal strata in the tunnel is classified according to the type of hazardous gas: When the area is classified as a low-risk zone, staff may enter for ventilation but may not remain there for more than 2 hours. This is a medium-risk area: staff may enter for ventilation, but not for more than 0.5 hours. This is a high-risk area: personnel are prohibited from entering during ventilation. This is an extremely dangerous area: personnel are prohibited from entering during ventilation.

[0014] Compared with the prior art, the present invention has the following beneficial effects: This invention establishes an innovative method for identifying geological disaster risks by employing methods such as causal mechanisms, hierarchical control, advanced drilling, and treatment plans. This method further enhances the ability to identify and prevent geological disasters induced by harmful gases in non-coal strata of tunnels, thereby ensuring construction safety. Attached Figure Description

[0015] Figure 1 This is a flowchart of a method for risk prevention and control of harmful gases in non-coal strata of tunnels. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figure 1 As shown, a method for risk prevention and control of harmful gases in non-coal strata of tunnels includes: S100: Advanced exploration to determine the geological structure of non-coal strata in tunnels and analyze the types of harmful gases produced by the geological structure; Advanced detection methods include: geological survey, geophysical exploration, advanced drilling, pilot pit method, and advanced borehole detection.

[0018] Hazardous gas types include: hydrogen sulfide, methane, carbon monoxide, sulfur dioxide, carbon dioxide, nitrogen oxides, ammonia, hydrogen, and nitrogen.

[0019] Common hazardous gas types encountered during tunnel excavation in non-coal strata include nine types: methane (CH4), carbon monoxide (CO), carbon dioxide (CO2), hydrogen sulfide (H2S), nitrogen dioxide (NO2), sulfur dioxide (SO2), ammonia (NH3), hydrogen (H2), and nitrogen (N2). Methane, carbon monoxide, sulfur dioxide, ammonia, and hydrogen pose an explosion risk; methane, carbon monoxide, and hydrogen sulfide are flammable. Carbon dioxide, hydrogen sulfide, nitrogen dioxide, sulfur dioxide, and ammonia are readily soluble in water.

[0020] Mechanism of harmful gas formation in carbonaceous rocks: Carbonaceous rocks are weak rock layers. During tectonic movements, especially fault activity, they are prone to forming folding and shrinkage structures, leading to local enrichment of carbonaceous rocks and thus local high-concentration gas accumulation. The main causes of harmful gases are hydrocarbon generation and metamorphism in carbonaceous rocks. The main types of harmful gases include methane (CH4), carbon monoxide (CO), and carbon dioxide (CO2).

[0021] Classification of Inorganic Hazardous Gases: Deep-source type: Magma serves as the reservoir and carrier of mantle-derived inorganic gases, and magmatic activity coincides with the release of inorganic gases such as carbon dioxide. Magma is rich in volatile components; during its ascent, the decrease in temperature and pressure allows CO2 and CH4 to precipitate from the magma and diffuse into the surrounding rocks, accumulating in favorable tectonic locations. During magma intrusion and eruption, the high-temperature baking effect of the magma also causes metamorphic thermal decomposition of carbonates, forming petrochemically derived carbon dioxide. Harmful gases commonly encountered when tunnels traverse igneous rock formations of this type include CH4, CO2, H2S, SO2, and helium (He).

[0022] Metamorphic types: ① Muddy rocks from various historical periods undergo metamorphism under the influence of regional thermodynamics and magmatic heat flow. Clay minerals, dolomite, calcite, and potassium mica all produce carbon dioxide during metamorphism. This carbon dioxide reacts with hydrogen gas from the mantle rising under thermodynamic forces and hydrogen gas released from magmatic heat flow to generate hydrocarbon gases. When magma intrudes or penetrates coal-bearing strata along bedding planes, it often promotes metamorphism in the coal seams. Gases released during metamorphism can form natural gas reservoirs when they encounter strata with favorable reservoir conditions; ② Metamorphic rocks can produce various harmful gases depending on the composition of their parent rocks, the type of metamorphism, and the metamorphic environment. For example, gneiss is primarily a parent rock of igneous rocks, which originally contained various primary gases from the mantle magma. These gases were kept under high temperature and pressure during metamorphism, and either were released from the igneous rocks or underwent a series of chemical reactions to form new gases. Marble, on the other hand, is a parent rock of carbonate rocks, which can generate carbon dioxide during high-temperature pyrolysis, low-temperature hydrolysis, and acidic dissolution in groundwater. Pure carbonates only begin to decompose at 825℃ when anhydrous, but impure carbonates begin to produce carbon dioxide at 75℃ when water is present. Marine limestone decomposes to produce large amounts of carbon dioxide at an underground temperature of 150℃.

[0023] Geothermal fluid types. Atmospheric precipitation or seawater seeps into the deep strata along fractured rock zones, is heated by magmatic heat or other geothermal flows, and then returns to the Earth's surface along tectonic fracture zones, forming hot brine or hot springs. During its infiltration into the Earth's crust, surface water dissolves easily soluble substances; during its heating process in the deeper layers, it adsorbs gases and volatile substances from the magmatic heat flow; and during its return to the surface, it can melt (dissolve) specific substances and carry easily fusible and volatile minerals from deep sources to the shallower parts of the Earth's crust. Therefore, hot brine or hot springs contain various metallic and non-metallic salt minerals, as well as various hydrocarbon and non-hydrocarbon gases.

[0024] Types of magmatic intrusion. Naturally formed igneous rocks mainly depend on two basic processes: the origin of magma and the evolution of magma, during which gases such as CH4, CO2, H2S, SO2, and helium (He) are formed.

[0025] Storage and transport characteristics of inorganically formed hazardous gases. The development of hazardous gases is strictly controlled by tectonic activity zones, especially the composite zones of different tectonic systems or combinations, which are favorable areas for the formation, emission, and accumulation of inorganically formed gases. Based on their functional differences during the accumulation process, gas source faults can be divided into four types: 1) Gas-forming fractures (medium-deep shear and compressive shear fractures, and shallow compressive shear fractures under special conditions); 2) Gas transmission fracture (shear strike-slip fracture and extension fracture); 3) Gas storage failure (tensile failure); 4) Gas sealing fracture (compressive and compressive shear slip fracture).

[0026] S200: Classify the hazard level of hazardous gases in non-coal strata of tunnels according to the type of hazardous gases, establish a disaster risk identification standard for non-coal hazardous gases based on the surrounding rock and gas emission conditions, and determine the risky locations based on the disaster risk identification standard for non-coal hazardous gases.

[0027] The principles for classifying the hazard levels of harmful gases are as follows: For hydrogen sulfide, Extremely high hazard zone: Hydrogen sulfide content α ≥ 0.002%; High-risk area: Hydrogen sulfide content 0.0198% ≤ α < 0.0502%; Moderately hazardous area: Hydrogen sulfide content 0.00066% ≤ α < 0.0198%; Low-risk area: Hydrogen sulfide content 0.000000041% ≤ α < 0.00066%; For methane, Extremely high hazard zone: methane content 5% ≤ α < 16% or α ≥ 43%; High-risk area: methane content 16% ≤ α < 43%; Moderate hazard zone: Methane content 5% ≤ α < 16%; Low-risk area: methane content α < 0.5%; For carbon monoxide, Extremely high risk area: carbon monoxide content α ≥ 0.04%; High-risk area: Carbon monoxide content ≤ α < 0.0048%; Moderate hazard zone: Carbon monoxide content 0.0024% ≤ α < 0.0048%; Low-risk area: Carbon monoxide content 0.0009% ≤ α < 0.0024%; For sulfur dioxide, Extremely high hazard zone: Sulfur dioxide content α ≥ 0.05%; High-risk area: Sulfur dioxide content ≤ α < 0.002%; Moderately hazardous area: Sulfur dioxide content 0.0005% ≤ α < 0.002%; Low-risk area: Sulfur dioxide content 0.000002% ≤ α < 0.0005%; Regarding carbon dioxide, Extremely high risk area: carbon dioxide content α ≥ 6%; High-risk area: Carbon dioxide content 5% ≤ α < 6%; Moderate hazard zone: Carbon dioxide content 0.5% ≤ α < 5%; Low-risk area: Carbon dioxide content ≤ α < 0.5%; For nitrogen oxides, Extremely high hazard zone: Nitrogen oxide content α ≥ 0.025%; High-risk area: Nitrogen oxide content ≤ α < 0.025%; Moderately hazardous area: Nitrogen oxide content ≤ α < 0.00025%; Low-risk area: Nitrogen oxide content ≤ α < 0.0000034%; For ammonia, Extremely high risk area: ammonia content α ≥ 30%; High-risk area: Ammonia content ≤ α < 30%; Moderately hazardous area: Ammonia content 0.004% ≤ α < 0.05%; Low-risk area: Ammonia content 0.0000132% ≤ α < 0.004%; For hydrogen, Extremely high danger zone and highly dangerous zone: hydrogen content 5% ≤ α < 74%; For nitrogen, Extremely high risk area, high risk area and moderate risk area: 19.5%≤α<74%.

[0028] The criteria for identifying disaster risks caused by non-coal hazardous gases are as follows: Low risk: There are fractured anomalies and non-coal hazardous gases are briefly released. Brief release means the duration is less than 1 minute and the gas dissipates rapidly. Moderate risk: There are abnormal fractures and intermittent jetting of non-coal hazardous gases, with intermittent jetting lasting 1-5 minutes and accompanied by local accumulation; High risk: There are fractured anomalies and continuous emission of non-coal hazardous gases, with continuous emission lasting for ≥5 minutes and gas pressure <10kPa; Extremely high risk: There are abnormal fracture bodies and continuous emission of non-coal hazardous gases, with the continuous emission lasting for ≥5 minutes and the gas pressure ≥10kPa.

[0029] S300: Hazardous gas monitoring points are set up in high-risk locations to monitor the concentration of hazardous gases and wind speed in the tunnel in real time; When the risk of disaster caused by non-coal hazardous gases is identified as... When the risk level is low, strengthen monitoring; When the risk level is moderate, strengthen monitoring, conduct deeper and more frequent targeted drilling, and collect gas samples for indoor gas composition analysis. When at high risk, strengthen monitoring, conduct deeper and more frequent targeted drilling, collect gas samples for indoor gas composition analysis, and develop specific detection and ventilation plans; When the risk level is extremely high, strengthen monitoring, conduct deeper and more frequent targeted drilling, collect gas samples for indoor gas composition analysis, and develop specific detection and ventilation plans.

[0030] The concentration of harmful gases and the wind speed in the tunnel should be monitored in real time. The monitoring location and scope should meet the following requirements: 1) In the airflow and return airflow of the excavation face, in the airflow within 20m of the blasting site, and at the site of local collapse and roof fall.

[0031] 2) In the airflow of the tunnel's main return air.

[0032] 3) In the airflow within 10m before and after the local fan and electrical switch.

[0033] 4) In the airflow within 20m of various work trolleys and machinery.

[0034] 5) In the airflow within 20m of the motor and its switch.

[0035] 6) Places where harmful gases tend to accumulate, such as tunnels and chambers.

[0036] 7) Monitoring Point Layout: Generally, five monitoring points should be set up for each cross-section: one at the arch crown, one on each side of the arch waist, and one on each side of the road shoulder 1.5-2.0m above the road shoulder. In special cases or when the patterns are understood, at least three monitoring points must be set up for each cross-section: one at the arch crown, and one on each side of the road shoulder 1.5-2.0m above the road shoulder. The average value of the monitoring data for this cross-section should be used to calculate the concentration of harmful gases.

[0037] Requirements for monitoring hazardous gases: 1) A clearly visible record board should be set up at each testing location. Each test result should be promptly recorded in the gas monitoring logbook and on the record board, and reported level by level. Monitoring personnel must implement a hazardous gas patrol inspection system.

[0038] 2) Manual patrol inspection. Manual patrol inspection uses portable hazardous gas detectors and alarms. These primarily detect toxic and hazardous gases such as hydrogen sulfide, carbon monoxide, nitrogen dioxide, sulfur dioxide, ammonia, and methane, and are conducted by dedicated personnel.

[0039] 3) Automatic Monitoring. The automatic hazardous gas monitoring system automatically collects a set of data from each probe every 5 minutes, transmitting it to the computer in the control room at the tunnel entrance for display, recording, analysis, and storage. The system automatically calculates the average and maximum concentrations and wind speeds for the entire day, and all monitoring data is saved. The handheld system is controlled according to shift handover inspections, process inspections, and a three-inspection-per-blast system. The detection results are included in the tunnel entrance log management.

[0040] 4) Wind speed detection. Detect and record the average wind speed at this cross-section.

[0041] 5) Data Recording. Data records should be continuous and complete, and data should be locked in a timely manner. Each monitoring point data file must indicate necessary information such as the mileage location of the monitoring point, the monitoring time, and the construction area of ​​the working face.

[0042] 6) Data Use and Storage. Monitoring data should be exported promptly and backed up properly.

[0043] When the concentration of harmful gases is detected to be in an extremely high danger zone, personnel inside the tunnel should be evacuated. Construction can only resume when the concentration of harmful gases drops to a low danger zone.

[0044] S400: Implement prevention and control measures based on monitoring data and risk levels.

[0045] Step S400 includes: S401: Ventilate during construction; Based on the data monitored by the hazardous gas monitoring points in step S300, the hazardous gas hazard levels in the non-coal strata of the tunnel are classified according to the type of hazardous gas: When the area is classified as a low-risk zone, staff may enter for ventilation but may not remain there for more than 2 hours. This is a medium-risk area: staff may enter for ventilation, but not for more than 0.5 hours. This is a high-risk area: personnel are prohibited from entering during ventilation. This is an extremely dangerous area: personnel are prohibited from entering during ventilation.

[0046] 1) During the construction of hazardous gas work areas, an organizational system and management system for ventilation inspection, testing and monitoring should be established to measure parameters such as wind speed, air volume and concentration.

[0047] 2) The ventilation system of the tunnel for harmful gases should be arranged in a reasonable manner according to the ventilation method. The ventilation equipment such as fans and ducts should be selected in a reasonable manner according to the required air volume. Local fans and jet fans can be installed in places where gases are prone to accumulate to enhance ventilation.

[0048] 3) Each excavation face must have independent ventilation. It is strictly forbidden to connect ventilation between any two working faces to avoid the spread of harmful gases.

[0049] 4) The ventilation arrangement for tunnel construction involving harmful gases should take into account the effect of natural wind at the tunnel entrance, and if necessary, measures such as installing pneumatic fans to prevent backdraft should be taken.

[0050] 5) During construction, it should be ensured that the concentration of harmful gases at any location is lower than the permissible safety standards for occupational exposure to harmful factors in railway gas tunnels and workplaces, as specified in the technical specifications for railway gas tunnels.

[0051] S402: Conduct construction blasting; When the gas detection report contains methane, carbon monoxide, hydrogen sulfide, ammonia and hydrogen, sodium bicarbonate solution is used for the mud and water bag making while water pressure blasting is used. The dust suppression spraying in the tunnel is a weak alkaline NaHCO3 solution to reduce the concentration of hydrogen sulfide gas. S403: Structural protection, hazardous gas structural protection sections are protected by different levels of reinforcement, seepage prevention materials and explosion-proof electrical equipment, similar to gas-prone sections; S404: To seal and exhaust harmful gases; 1) In areas where harmful gases are overflowing, measures such as advanced perimeter grouting and radial grouting after excavation can be used to seal the harmful gas channels in the surrounding rock, thereby reducing the amount of harmful gas overflowing, depending on the occurrence conditions, overflow and replenishment of the harmful gases.

[0052] 2) In areas with harmful gases, exhaust pipes can be used to discharge the gases outside the tunnel.

[0053] S405: Take personal protective measures.

[0054] 1) In sections with hazardous gases, large machinery must be used for construction and minimal human intervention. Before each process in the hazardous gas tunnel, a strict safety briefing system must be implemented for the workers.

[0055] 2) Personnel protection measures should be taken. Respiratory isolation equipment for toxic gases should be configured according to the maximum number of workers at the same time near the working face. If the concentration of harmful gases exceeds the standard or a sudden explosion occurs, the equipment can be worn immediately for self-rescue.

[0056] 3) When the amount of gas overflow increases rapidly, an alarm should be sounded immediately and all personnel inside the cave should be evacuated.

[0057] If real-time monitoring shows that the gas concentration is in an extremely high danger zone, then S404 or S405 should be executed first.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for risk prevention and control of harmful gases in non-coal strata of tunnels, characterized in that, include: S100: Advanced exploration to determine the geological structure of non-coal strata in tunnels and analyze the types of harmful gases produced by the geological structure; S200: Classify the hazard level of hazardous gases in non-coal strata of tunnels according to the type of hazardous gases, establish a disaster risk identification standard for non-coal hazardous gases based on the surrounding rock and gas emission conditions, and determine the risky locations based on the disaster risk identification standard for non-coal hazardous gases. S300: Hazardous gas monitoring points are set up in high-risk locations to monitor the concentration of hazardous gases and wind speed in the tunnel in real time; S400: Implement prevention and control measures based on monitoring data and risk levels.

2. The method for risk prevention and control of harmful gases in non-coal strata of tunnels according to claim 1, characterized in that, In step S100, the advanced detection method includes: Geological survey method, geophysical exploration method, advanced drilling method, advanced pilot tunnel method, and advanced borehole detection method.

3. The method for risk prevention and control of harmful gases in non-coal strata of tunnels according to claim 1, characterized in that, In step S100, the types of harmful gases include: Hydrogen sulfide, methane, carbon monoxide, sulfur dioxide, carbon dioxide, nitrogen oxides, ammonia, hydrogen, and nitrogen.

4. The method for risk prevention and control of harmful gases in non-coal strata of tunnels according to claim 1, characterized in that, The principle for classifying the hazard levels of the harmful gases is as follows: For hydrogen sulfide, Extremely high hazard zone: Hydrogen sulfide content α ≥ 0.002%; High-risk area: Hydrogen sulfide content 0.0198% ≤ α < 0.0502%; Moderately hazardous area: Hydrogen sulfide content 0.00066% ≤ α < 0.0198%; Low-risk area: Hydrogen sulfide content 0.000000041% ≤ α < 0.00066%; For methane, Extremely high hazard zone: methane content 5% ≤ α < 16% or α ≥ 43%; High-risk area: methane content 16% ≤ α < 43%; Moderate hazard zone: Methane content 5% ≤ α < 16%; Low-risk area: methane content α < 0.5%; For carbon monoxide, Extremely high risk area: carbon monoxide content α ≥ 0.04%; High-risk area: Carbon monoxide content ≤ α < 0.0048%; Moderate hazard zone: Carbon monoxide content 0.0024% ≤ α < 0.0048%; Low-risk area: Carbon monoxide content 0.0009% ≤ α < 0.0024%; For sulfur dioxide, Extremely high hazard zone: Sulfur dioxide content α ≥ 0.05%; High-risk area: Sulfur dioxide content ≤ α < 0.002%; Moderately hazardous area: Sulfur dioxide content 0.0005% ≤ α < 0.002%; Low-risk area: Sulfur dioxide content 0.000002% ≤ α < 0.0005%; Regarding carbon dioxide, Extremely high risk area: carbon dioxide content α ≥ 6%; High-risk area: Carbon dioxide content 5% ≤ α < 6%; Moderate hazard zone: Carbon dioxide content 0.5% ≤ α < 5%; Low-risk area: Carbon dioxide content ≤ α < 0.5%; For nitrogen oxides, Extremely high hazard zone: Nitrogen oxide content α ≥ 0.025%; High-risk area: Nitrogen oxide content ≤ α < 0.025%; Moderately hazardous area: Nitrogen oxide content ≤ α < 0.00025%; Low-risk area: Nitrogen oxide content ≤ α < 0.0000034%; For ammonia, Extremely high risk area: ammonia content α ≥ 30%; High-risk area: Ammonia content ≤ α < 30%; Moderately hazardous area: Ammonia content 0.004% ≤ α < 0.05%; Low-risk area: Ammonia content 0.0000132% ≤ α < 0.004%; For hydrogen, Extremely high danger zone and highly dangerous zone: hydrogen content 5% ≤ α < 74%; For nitrogen, Extremely high risk area, high risk area and moderate risk area: 19.5%≤α<74%.

5. The method for risk prevention and control of harmful gases in non-coal strata of tunnels according to claim 4, characterized in that, The criteria for identifying the disaster risk caused by non-coal hazardous gases are as follows: Low risk: There are fractured anomalies and non-coal hazardous gases are briefly released. Brief release means the duration is less than 1 minute and the gas dissipates rapidly. Moderate risk: There are abnormal fractures and intermittent jetting of non-coal hazardous gases, with intermittent jetting lasting 1-5 minutes and accompanied by local accumulation; High risk: There are fractured anomalies and continuous emission of non-coal hazardous gases, with continuous emission lasting for ≥5 minutes and gas pressure <10kPa; Extremely high risk: There are abnormal fracture bodies and continuous emission of non-coal hazardous gases, with the continuous emission lasting for ≥5 minutes and the gas pressure ≥10kPa.

6. The method for risk prevention and control of harmful gases in non-coal strata of tunnels according to claim 1, characterized in that, In step S300, the monitoring points and their ranges must meet the following requirements: 1) In the airflow and return airflow of the excavation face, in the airflow within 20m of the blasting site, and at the site of local collapse and roof fall; 2) In the airflow of the tunnel's main return air; 3) In the airflow within 10m before and after the local fan and electrical switches; 4) Within 20m of various work trolleys and machinery in the airflow; 5) In the airflow within 20m of the motor and its switch; 6) Areas where harmful gases easily accumulate, such as tunnels and chambers; Monitoring point layout: Five monitoring points are set up for each cross section, one at the top of the arch, one on each side of the arch waist, and one on each side wall shoulder 1.5~2.0m above the road shoulder; In special circumstances and under conditions where the patterns are understood, at least three monitoring points must be set up for each cross section: one at the arch top, one on each of the two side walls within a range of 1.5 to 2.0 meters above the road shoulder, and the average value of the monitoring data for that cross section should be used to calculate the concentration of harmful gases.

7. The method for risk prevention and control of harmful gases in non-coal strata of tunnels according to claim 5, characterized in that, In step S300, when the risk of disaster caused by non-coal hazardous gases is identified as... When the risk level is low, strengthen monitoring; When the risk level is moderate, strengthen monitoring, conduct deeper and more frequent targeted drilling, and collect gas samples for indoor gas composition analysis. When at high risk, strengthen monitoring, conduct deeper and more frequent targeted drilling, collect gas samples for indoor gas composition analysis, and develop specific detection and ventilation plans; When the risk level is extremely high, strengthen monitoring, conduct deeper and more frequent targeted drilling, collect gas samples for indoor gas composition analysis, and develop specific detection and ventilation plans.

8. The method for risk prevention and control of harmful gases in non-coal strata of tunnels according to claim 7, characterized in that, Step S400 includes: S401: Ventilate during construction; S402: Conduct construction blasting; When the gas detection report contains methane, carbon monoxide, hydrogen sulfide, ammonia and hydrogen, sodium bicarbonate solution is used for the mud and water bag making while water pressure blasting is used. The dust suppression spraying in the tunnel is a weak alkaline NaHCO3 solution to reduce the concentration of hydrogen sulfide gas. S403: Structural protection, hazardous gas structural protection sections are protected by different levels of reinforcement, seepage prevention materials and explosion-proof electrical equipment, similar to gas-prone sections; S404: To seal and exhaust harmful gases; S405: Take personal protective measures.

9. The method for risk prevention and control of harmful gases in non-coal strata of tunnels according to claim 8, characterized in that, If real-time monitoring shows that the gas concentration is in an extremely high danger zone, then S404 or S405 should be executed first.

10. The method for risk prevention and control of harmful gases in non-coal strata of tunnels according to claim 8, characterized in that, In step S401, based on the data monitored by the hazardous gas monitoring points in step S300, the hazardous gas hazard levels of the non-coal strata in the tunnel are classified according to the type of hazardous gas: When the area is classified as a low-risk zone, staff may enter for ventilation but may not remain there for more than 2 hours. This is a medium-risk area: staff may enter for ventilation, but not for more than 0.5 hours. This is a high-risk area: personnel are prohibited from entering during ventilation. This is an extremely dangerous area: personnel are prohibited from entering during ventilation.

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