A method and apparatus for grading the hazard of hydrogen sulfide gas in a tunnel

Abstract

This invention relates to the field of hazard assessment of hydrogen sulfide gas in tunnels, specifically to a method and equipment for classifying the hazard level of hydrogen sulfide gas in tunnels. The classification method includes the following steps: establishing assessment standard one based on the presence of sulfur-bearing strata and the temperature and pressure environment of the tunnel area; establishing assessment standard two based on the presence of structural fractures in the tunnel; establishing assessment standard three based on the development level and migration path of groundwater; establishing assessment standard four based on the lithology of the tunnel strata; calculating the assessment scores obtained according to assessment standards one, two, three, and four to obtain a hazard index score; and determining the hazard level of hydrogen sulfide gas in the tunnel based on the hazard index score. The classification method of this invention can simply and quickly evaluate the hazard level of hydrogen sulfide gas in tunnels and has strong engineering practicality.

Description

Technical Field

[0001] This invention relates to the field of hazardous assessment of hydrogen sulfide gas in tunnels, and particularly to a method and equipment for classifying the hazardous level of hydrogen sulfide gas in tunnels. Background Technology

[0002] During the exploration, construction, and operation of tunnels and underground engineering projects, traversing geological units rich in hydrogen sulfide (H2S) is a common and significant safety risk. H2S is a highly toxic, flammable, and explosive acidic gas with a density higher than air. It tends to accumulate in low-lying areas and poorly ventilated corners of tunnels, posing a dual threat to personnel safety and engineering facilities.

[0003] Currently, the industry's H2S risk prevention and control mainly relies on a lagging early warning model that combines point monitoring with experience-based grading. Monitoring methods generally employ fixed or handheld gas detectors to measure concentrations at limited key locations. This method has poor spatial representativeness and cannot perceive the gas migration and accumulation status across the entire tunnel cross-section and depth in real time, resulting in monitoring blind spots. The hazard level classification of hydrogen sulfide gas is mostly based on instantaneous, isolated concentration thresholds (such as 100ppm, 300ppm, 1000ppm). This grading method fails to dynamically integrate multi-source heterogeneous information such as geological structure, rock fracture development, groundwater activity, tunnel excavation speed, and ventilation efficiency, leading to insufficient accuracy and foresight in early warning. Since the above grading methods are essentially contact-based and reactive, an alarm is only triggered when H2S has migrated, accumulated, and reached a certain concentration at the detection point. For tunnel projects with complex geological conditions and the sudden and uncertain nature of gas outbursts, the reserved emergency response time window is too short, making it difficult to achieve true proactive risk prediction.

[0004] Therefore, how to achieve non-contact, advanced, dynamic, and intelligent comprehensive early warning and classification of H2S disaster risks in front of and around tunnel construction areas has become a core technical challenge that urgently needs to be overcome in this field. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide a method and equipment for classifying the hazard level of hydrogen sulfide gas in tunnels.

[0006] In a first aspect, the present invention provides a method for classifying the hazard level of hydrogen sulfide gas in tunnels, comprising the following steps:

[0007] An assessment standard was established based on the presence of sulfur-bearing strata and the temperature and pressure environment in the tunnel area. Evaluation Standard Two is established based on the presence of structural fractures in the tunnel. Assessment Standard Three is established based on the development level and migration pathways of groundwater; Evaluation Standard Four was established based on the lithology of the tunnel strata. The assessment scores obtained according to assessment criteria one, two, three, and four are used to calculate the hazard index score, and the hazard level of hydrogen sulfide gas in the tunnel is determined based on the hazard index score.

[0008] In the above technical solution, different factors are used to assess the hazard of hydrogen sulfide gas. Assessment standard one is established based on the presence of sulfur-bearing strata and temperature and pressure environment; assessment standard two is established based on the presence of tunnel structural fracture characteristics; assessment standard three is established based on the development level of groundwater and the presence of migration paths; and assessment standard four is established based on the lithology of the strata. By integrating the four factors and establishing a scoring system, the assessment scores obtained from assessment standard one, assessment standard two, assessment standard three, and assessment standard four are used to calculate the hazard index score. The hazard level of hydrogen sulfide gas in the tunnel is determined based on the hazard index score, thus transforming qualitative geological description into quantitative indicators and avoiding the subjectivity of experience-based judgment.

[0009] Preferably, the presence of sulfur-bearing strata and the temperature and pressure environment are obtained based on geological data, geological mapping, and drilling data of the tunnel area.

[0010] Preferably, the sulfur-bearing strata include sulfate rock strata, coal-bearing strata, oil and gas reservoirs, sulfur-bearing metal ore anomaly zones, hot spring zones, organic-rich mudstone and shale strata, and gypsum-bearing carbonate rock strata. The temperature and pressure environment includes temperature and pressure. Scoring is performed based on the type of sulfur-bearing strata present in the tunnel area and the temperature and pressure environment of the tunnel area. The scores are then summed to obtain the evaluation score obtained according to evaluation standard one.

[0011] Preferably, evaluation criterion one is: Regarding the presence of sulfur-bearing strata, if any of the following strata—sulfate rock strata, coal-bearing strata, or oil and gas reservoirs—are present along the tunnel axis and in the vicinity, the score is 50. When the underlying strata of the tunnel contain any one of the following types of strata: sulfate rock strata, coal-bearing strata, or oil and gas reservoirs, the score is 45. When the tunnel axis and the surrounding strata contain any of the following types of strata: sulfur-bearing metal mineral anomaly zone, hot spring zone, etc., the score is 40. When the underlying strata contain either a sulfur-bearing metal ore anomaly zone or a hot spring zone, the score is 35. When the tunnel axis and the surrounding strata contain either gypsum-bearing carbonate rock strata or organic-rich mudstone and shale strata, the score is 30. When the underlying strata of the tunnel contain either gypsum-bearing carbonate rock strata or organic-rich mudstone and shale strata, the score is 25; For the aforementioned temperature and pressure environment, when the temperature in and around the tunnel axis is >80℃ or the pressure is ≥3000m, the score is 5; When the temperature in the tunnel axis and nearby strata is 60℃≤temperature≤80℃ or 2000m≤pressure<3000m, the score is 4; When the tunnel axis and nearby strata have a temperature of 50℃≤Temperature<60℃ or a pressure of 1000m≤Pressure<2000m, the score is 3; When the temperature in and around the tunnel axis is between 37℃ and 50℃ or between 500m and 1000m, the score is 2. If the temperature in the tunnel axis and nearby strata is <37℃ or the pressure is <500m, the score is 0; When the temperature of the underlying strata is >80℃, the score is 4; When the underlying strata of the tunnel have a temperature of 60℃≤80℃, the score is 3; When the underlying strata of the tunnel have a temperature of 50℃≤Temperature<60℃, the score is 2; When the temperature of the underlying strata of the tunnel is 37℃≤Temperature<50℃, the score is 1; If the temperature of the underlying strata is <37℃, the score is 0.

[0012] Preferably, the structural fracture characteristics of the tunnel are obtained through geophysical exploration methods, including seismic wave method and resistivity method.

[0013] Preferably, the tunnel structural fracture characteristics include faults, fold zones, fracture zones, and densely jointed zones. Scoring is based on the type of tunnel structural fracture characteristics, with the second evaluation criterion being: When there are faults in the tunnel axis and the underlying strata, the score is 25. When there are fold zones in and around the tunnel axis, the score is 20. When there is a fold zone in the underlying strata of the tunnel, the score is 15; When there are fracture zones and densely jointed zones in and around the tunnel axis, the score is 15. When there are fracture zones and dense joint zones in the underlying strata of the tunnel, the score is 10.

[0014] Preferably, the degree of development and migration path of groundwater are obtained based on tunnel geological mapping, geophysical exploration, and drilling data.

[0015] Preferably, a score is awarded based on the development level and migration path of groundwater in the tunnel, with evaluation criterion three being: When there are stream-like water seepage along the tunnel axis and in the nearby strata, the score is 10; when there are sulfur-bearing strata beneath the tunnel and stream-like water seepage near the tunnel body, the score is 8. When there is rain-like to small-stream water discharge in and around the tunnel axis, the score is 8; when there is sulfur-bearing strata beneath the tunnel and rain-like to small-stream water discharge near the tunnel body, the score is 6. When there is damp to dripping water in the tunnel axis and nearby strata, the score is 4; when there is sulfur-bearing strata beneath the tunnel and there is damp to dripping water near the tunnel body, the score is 2. When the tunnel axis and the surrounding strata are dry and waterless, the score is 0.

[0016] Preferably, the lithology of the tunnel strata is obtained based on geological data, geological mapping, and drilling data of the tunnel area.

[0017] Preferably, the lithology of the tunnel strata includes mudstone, dense limestone, mudstone interbedded with sandstone, and sandstone interbedded with mudstone. A scoring system is established based on the lithology of the tunnel strata in and around the tunnel body. Evaluation criterion four is as follows: When mudstone or dense limestone is present in the tunnel axis and nearby strata, the score is 10. When mudstone interbedded with sandstone exists in the tunnel axis and nearby strata, the score is 6; When there are alternating layers of mudstone and sandstone in and around the tunnel axis, the score is 4. When sandstone interbedded with mudstone exists in the tunnel axis and nearby strata, the score is 2; When sandstone or similar materials are present in the tunnel axis and nearby strata, the score is 0.

[0018] Preferably, the assessment scores obtained according to assessment criteria one, assessment criteria two, assessment criteria three, and assessment criteria four are summed. The method for calculating the risk index score is as follows: S = a + b + c + d S represents the risk index score, a represents the assessment score obtained according to assessment standard one, b represents the assessment score obtained according to assessment standard one, c represents the assessment score obtained according to assessment standard three, and d represents the assessment score obtained according to assessment standard four.

[0019] Preferably, the hazard level of hydrogen sulfide gas is divided into four levels, with the degree of hazard from low to high being low hazard, medium hazard, moderate hazard, and high hazard, and the corresponding hazard index scores being S<40, 40≤S<60, 60≤S<80, and 80≤S<100, respectively.

[0020] In a second aspect, the present invention provides a classification device for the hazard level of hydrogen sulfide gas in tunnels, comprising: The assessment module is used to establish assessment standard one based on the presence of sulfur-bearing strata and the temperature and pressure environment in the tunnel area. The second assessment module is used to establish assessment standard two based on the presence of structural fracture characteristics in the tunnel. The assessment module consists of three parts, which are used to establish assessment criteria three based on the development level and migration path of groundwater. The assessment module four is used to establish assessment standard four based on the lithology of the tunnel strata. The calculation module is used to calculate the risk index score based on the assessment scores obtained according to assessment criteria one, assessment criteria two, assessment criteria three, and assessment criteria four. The grading module is used to determine the hazard level of hydrogen sulfide gas in the tunnel based on the hazard index scores.

[0021] Compared with the prior art, the beneficial effects of the present invention include: 1. This invention provides a method for classifying the hazard level of hydrogen sulfide gas in tunnels. By comprehensively analyzing sulfur-bearing strata, temperature and pressure environment, tectonic fracture characteristics, the development and migration path of groundwater, and stratum lithology factors, a quantitative method is used to evaluate the hazard level of hydrogen sulfide gas in tunnels, making the hazard assessment more accurate and intuitive, and ensuring the safety of personnel.

[0022] 2. This invention provides a classification method for the hazard level of hydrogen sulfide gas in tunnels. The method is highly targeted, simple, and reliable, providing technical support for developing targeted engineering measures during tunnel design and construction. It can identify high-risk sections in advance, reserve sufficient emergency preparation time, and avoid casualties and project delays caused by sudden hydrogen sulfide leaks. Attached Figure Description

[0023] Figure 1 This is a flowchart of a method for classifying the hazard level of hydrogen sulfide gas in tunnels according to the present invention. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0025] Example 1 A method for classifying the hazard level of hydrogen sulfide gas in tunnels, such as... Figure 1 As shown, it includes the following steps: An assessment standard was established based on the presence of sulfur-bearing strata and the temperature and pressure environment in the tunnel area. Evaluation Standard Two is established based on the presence of structural fractures in the tunnel. Assessment Standard Three is established based on the development level and migration pathways of groundwater; Evaluation Standard Four was established based on the lithology of the tunnel strata. The assessment scores obtained according to assessment criteria one, two, three, and four are used to calculate the hazard index score, and the hazard level of hydrogen sulfide gas in the tunnel is determined based on the hazard index score.

[0026] In some embodiments, the presence of sulfur-bearing strata and the temperature and pressure environment are obtained based on geological data, geological mapping, and drilling data of the tunnel area.

[0027] In some embodiments, the sulfur-bearing strata include sulfate rock strata, coal-bearing strata, oil and gas reservoirs, sulfur-bearing metal mineral anomaly zones, hot spring zones, organic-rich mudstone and shale strata, and gypsum-bearing carbonate rock strata. The temperature and pressure environment includes temperature and pressure. A score a1 is assigned based on the type of sulfur-bearing strata present in the tunnel area, and a score a2 is assigned based on the temperature and pressure environment of the tunnel area, resulting in a total score a = a1 + a2. Evaluation criterion one is: For the presence of sulfur-bearing strata, when any of the following strata—sulfate rock, coal-bearing strata, or oil and gas reservoirs—are present along the tunnel axis and in the vicinity, the score a1=50. When the underlying strata of the tunnel contain any one of the following types of strata: sulfate rock strata, coal-bearing strata, or oil and gas reservoirs, the score a1=45; When the tunnel axis and the surrounding strata contain any of the following types of strata: sulfur-bearing metal mineral anomaly zone, hot spring zone, the score a1=40; When the underlying strata contain either a sulfur-bearing metal mineral anomaly zone or a hot spring zone, the score a1=35; When the tunnel axis and the surrounding strata contain either gypsum-bearing carbonate rock strata or organic-rich mudstone and shale strata, the score a1=30; When the underlying strata of the tunnel contain either gypsum-bearing carbonate rock strata or organic-rich mudstone and shale strata, the score a1=25; For temperature and pressure environments, when the temperature in and around the tunnel axis is >80℃ or the pressure is ≥3000m, the score a2=5; When the tunnel axis and nearby strata have a temperature of 60℃≤80℃ or a pressure of 2000m≤3000m, the score a2=4; When the tunnel axis and nearby strata have a temperature of 50℃≤Temperature<60℃ or a pressure of 1000m≤Pressure<2000m, the score a2=3; When the temperature in and around the tunnel axis is 37℃≤Temperature<50℃ or 500m≤Pressure<1000m, the score a2=2; When the temperature in the tunnel axis and nearby strata is <37℃ or the pressure is <500m, the score a2=0.

[0028] When the temperature of the underlying strata is >80℃, the score a2=4; When the underlying strata of the tunnel have a temperature of 60℃≤80℃, the score a2=3; When the underlying strata of the tunnel have a temperature of 50℃≤T<60℃, the score a2=2; When the temperature of the underlying stratum is 37℃≤temperature<50℃, the score a2=1; When the temperature of the underlying strata is <37℃, the score a2=0.

[0029] In tunnel engineering, the tunnel axis and surrounding strata refer to the geological area within a certain range of the tunnel design centerline (axis). It usually includes a space range extending a certain distance (such as 3-5 times the tunnel diameter) beyond the tunnel excavation outline. It is a high-risk area that is directly affected by construction disturbance and where hydrogen sulfide is prone to accumulate. The location of the axis is determined by the tunnel axis plan and longitudinal profile.

[0030] The underlying strata of a tunnel refer to the strata below the bottom of the tunnel body, that is, the lower part of the strata where the tunnel structure is located. Hydrogen sulfide may be released upward through fissures, groundwater and other channels.

[0031] Using methods such as borehole columnar sections and cross-hole seismic exploration, the sulfur-bearing strata (such as coal-bearing strata and sulfur-bearing metal ore layers) and temperature and pressure environments (such as high-temperature and high-pressure zones) below the tunnel bottom are determined. Among these, sulfate rock strata, coal-bearing strata, oil and gas reservoirs, sulfur-bearing metal ore anomaly zones, hot spring zones, organic-rich mudstone and shale strata, and gypsum-bearing carbonate rock strata are key sulfur-bearing strata types for assessing the hydrogen sulfide gas hazard in tunnel engineering. Sulfate rock strata contain sulfate minerals such as gypsum and anhydrite, which are easily reduced to produce hydrogen sulfide under high temperature and pressure, making them high-risk strata. Coal-bearing strata contain organic matter and pyrite, which can generate hydrogen sulfide through pyrolysis. Oil and gas reservoirs contain hydrogen sulfide-bearing natural gas, often associated with oil and gas reservoirs, and are sulfur-bearing strata that require special attention during tunnel construction. Sulfur-bearing metal ore anomaly zones are rich in sulfide minerals (such as pyrite), which can release hydrogen sulfide through oxidation or bacterial action. High-temperature groundwater in hot spring areas often contains hydrogen sulfide, reflecting the characteristics of deep sulfur-bearing strata. Organic matter-rich mudstone and shale strata can generate hydrogen sulfide through thermal evolution of organic matter, often serving as source rocks. In gypsum-bearing carbonate strata, the mixture of carbonate and sulfate rocks easily forms hydrogen sulfide-rich zones through dissolution. These strata are identified in tunnel engineering through geological mapping, drilling, and geophysical exploration, and assigned different risk scores based on their location (the axis and its vicinity or underlying strata).

[0032] Based on the presence of sulfur-bearing strata and the temperature and pressure environment in the tunnel area, the specific scores for a1 and a2 are shown in Table 1 below.

[0033] Table 1. Evaluation criteria established based on the presence of sulfur-bearing strata and temperature / pressure environment in the tunnel area.

[0034] In some embodiments, the tunnel structural fracture characteristics are obtained through geophysical exploration methods, including seismic wave method and resistivity method.

[0035] In some embodiments, the tunnel structural fracture features include faults, fold zones, fracture zones, and densely jointed zones. A score (b) is assigned based on the type of tunnel structural fracture feature present. Evaluation criterion two is: When there are deep and large fault zones in the tunnel axis and the underlying strata, the score b=25; When the tunnel axis and the surrounding strata contain folded zones that form the core of anticlines and synclines with capping conditions, the score b=20; When the underlying strata of the tunnel contain anticlines and synclines with capping conditions, the score b=15; When there are fracture zones or densely jointed zones in and around the tunnel axis, the score b=15; When there are fracture zones and dense joint zones in the underlying strata of the tunnel, the score b=10.

[0036] Faults are fracture surfaces where rock strata have undergone significant displacement, often accompanied by fracture zones, slickensides, and fault gouge. Folded belts exhibit bending deformation caused by compression of rock strata, classified as anticlines (upward arching) and synclines (downward depressions), with the core strata compressed and fractured, and the limb strata tilted. Fracture zones are densely fractured zones formed by tectonic stress, with highly interconnected fractures, often accompanied by rock block displacement, and their width ranges from several meters to tens of meters. Densely jointed zones are characterized by densely developed fine fracture surfaces (joints) in the rock strata, without significant displacement, and often arranged in a regular pattern (e.g., parallel joints, conjugate joints). Faults, folded belts, fractured belts, and densely jointed zones are identified using methods commonly used in this field.

[0037] The specific scores for assessment standard b, established based on the presence of structural fissures in tunnels, are shown in Table 2 below.

[0038] Table 2. Evaluation Criteria II Based on the Presence of Tunnel Structural Fractures

[0039] In some embodiments, the development level and migration path of groundwater are obtained based on tunnel geological mapping, geophysical exploration, and drilling data. Through geological mapping, geophysical exploration, drilling, etc., the hydrogeological conditions of the tunnel are analyzed to determine the water circulation system.

[0040] In some embodiments, a score (c) is assigned based on the development level and migration path of groundwater in the tunnel, and the third evaluation criterion is: When there is a stream of water in the tunnel axis and nearby strata, the score is c=10; when there is a sulfur-bearing stratum beneath the tunnel and a stream of water is present near the tunnel body, the score is c=8. When there is rain-like to small-stream water discharge in and around the tunnel axis, the score is c=8; when there is sulfur-containing strata beneath the tunnel, and there is a water circulation system and rain-like to small-stream water discharge near the tunnel body, the score is c=6. When there is damp to dripping water in the tunnel axis and nearby strata, the score is c=4; when there is sulfur-containing strata under the tunnel and there is a water circulation system and damp to dripping water near the tunnel body, the score is c=2. When the tunnel axis and the surrounding strata are dry and waterless, the score c=0.

[0041] In a water circulation system, water discharge in the form of streams, showers, small streams, dampness, and drips can be identified by its flow pattern, flow rate, pressure, and impact on the project. Streams are characterized by a distinct columnar or bundle-like flow with some pressure and a relatively large flow rate (usually >50 L / min), forming a continuous flow. Shower-like to small stream discharges refer to water discharges ranging from shower-like to small stream-like. These discharges are characterized by dense rain-like or fine stream-like flows with a moderate flow rate (10-50 L / min), no significant pressure, and flow out in a planar or linear manner along the fissure surface. Dampness-drip discharges consist only of wet rock walls or sporadic droplets, with an extremely small flow rate (<10 L / min), no pressure, and are mostly slow seepage from fissures. Dryness-free discharges indicate a completely dry rock wall with no trace of moisture and a flow rate of 0. Identification methods include visual observation or flow rate measurement.

[0042] The specific scoring for assessment standard 3c, established based on the development level and migration pathways of groundwater, is shown in Table 3 below.

[0043] Table 3. Assessment criteria established based on the development level and migration pathways of groundwater.

[0044] In some embodiments, the lithology of the tunnel strata is obtained based on geological data, geological mapping, and drilling data of the tunnel area.

[0045] In some embodiments, the tunnel strata lithology includes mudstone, dense limestone, mudstone interbedded with sandstone, and sandstone interbedded with mudstone. A score (d) is assigned based on the tunnel strata lithology type present in the tunnel body and surrounding area. Evaluation criterion four is: When mudstone or dense limestone is present in the tunnel axis and nearby strata, the score d=10; When mudstone interbedded with sandstone exists in the tunnel axis and nearby strata, the score d=6; When there are alternating layers of mudstone and sandstone in and around the tunnel axis, the score d=4; When sandstone interbedded with mudstone exists in the tunnel axis and nearby strata, the score d=2; When sandstone or similar materials are present in the tunnel axis and nearby strata, the score d=0.

[0046] Mudstone is a weak rock with low strength, and it is easily softened, muddied, and swelled when exposed to water. Dense limestone is a hard and brittle rock with high strength and usually good integrity. Mudstone interbedded with sandstone is dominated by mudstone, which is a weak matrix (mudstone) with relatively hard interlayers (sandstone), and it is interbedded or interlayered. Sandstone interbedded with mudstone is dominated by sandstone, which is a hard matrix (sandstone) with weak interlayers (mudstone).

[0047] The specific scoring for d, based on the assessment standard four established according to the tunnel strata lithology, is shown in Table 4 below.

[0048] Table 4. Evaluation Criteria Based on Tunnel Stratigraphy (Part Four)

[0049] The quantitative scores of the above four factors are summed, and the hazard level of hydrogen sulfide gas in the tunnel is determined based on the total index score. Specifically, the assessment scores obtained according to assessment standard one, assessment standard two, assessment standard three, and assessment standard four are summed. The calculation method for the hazard index score is as follows: S = a + b + c + d = a1 + a2 + b + c + d S represents the risk index score, a represents the assessment score obtained according to assessment standard one, b represents the assessment score obtained according to assessment standard one, c represents the assessment score obtained according to assessment standard three, and d represents the assessment score obtained according to assessment standard four.

[0050] The hazard level of hydrogen sulfide gas in tunnels is determined based on the total index score. The hazard level of hydrogen sulfide gas is divided into four levels, with the degree of hazard from low to high being low hazard, medium hazard, moderate hazard, and high hazard, respectively. The corresponding hazard index scores are S<40, 40≤S<60, 60≤S<80, and 80≤S<100.

[0051] The method and equipment for classifying the hydrogen sulfide gas hazard level in tunnels, developed by this invention, can comprehensively analyze sulfur-bearing strata, temperature and pressure environment, tectonic fracture characteristics, groundwater development and migration path, and lithological factors. It employs a quantitative method to evaluate the hydrogen sulfide gas hazard level in tunnels, making hazard assessment more accurate, intuitive, and targeted. The classification method is simple and reliable, effectively supporting tunnel design and guiding the safe construction and operation of tunnels in sulfur-bearing strata. This invention can also be used for the hazard classification of hydrogen sulfide harmful gases in tunnel engineering projects such as highways and hydropower stations.

[0052] Example 2 This embodiment uses the method of Embodiment 1 to provide a method for classifying the hazard level of hydrogen sulfide gas in tunnels, including the following steps: Based on regional geological data, geological mapping, drilling, etc., determine whether there are sulfate rock formations, oil and gas reservoirs, coal-bearing formations, gypsum-bearing carbonate rock formations, sulfur-bearing metal mineral anomaly zones, organic-rich mudstone and shale formations, hot spring zones, high-temperature and high-pressure environments, etc. in the tunnel body and underlying strata, and then assign a quantitative score. Geophysical exploration and drilling methods are used to detect the structural fracture characteristics of the tunnel (such as faults, folds, fracture zones, and dense joint zones), and quantitative scoring is performed. Through geological mapping, geophysical exploration, drilling, etc., the hydrogeological conditions of the tunnel are analyzed, the water circulation system (the degree of development and migration path of groundwater) is determined, and a quantitative score is given. Based on regional geological data, geological mapping, drilling, etc., determine whether there are mudstone, dense limestone or other cover layers in and around the tunnel body, and assign a quantitative score d. The scores of the above four indicators are summed, and the risk level of hydrogen sulfide gas in the tunnel is determined based on the total score.

[0053] Taking the section of a high-speed railway tunnel in Chongqing, from DK16+150 to +250, traversing the Guanyinxia anticline, as an example, the lithology near the tunnel is Triassic Feixianguan Formation argillaceous limestone, limestone, and mudstone, classified as Class III surrounding rock. Groundwater is not well-developed, but the underlying strata of the tunnel are Triassic Longtan Formation coal-bearing strata. On-site excavation tests showed a hydrogen sulfide concentration of 124 ppm, classifying this section as a highly dangerous area.

[0054] In step S1, the underlying strata of the tunnel body in the DK16+150~+250 section of a high-speed railway tunnel in Chongqing are the Triassic Longtan Formation coal-bearing strata, with a temperature of 26℃ and an elevation of about 310~320m. Let a1=45 and a2=0. In step S2, the DK16+150~+250 section of a high-speed railway tunnel in Chongqing crosses the Guanyinxia anticline, which is a narrow and asymmetrical torsional anticline with well-developed structural fractures and b=15. In step S3, groundwater is not developed in the DK16+150~+250 section of a high-speed railway tunnel in Chongqing, so c=0; In step S4, the tunnel section DK16+150~+250 of a high-speed railway tunnel in Chongqing is a region with mudstone, dense limestone and other caprocks, with d=10; In step S5, the quantitative scores of the above four factors are summed: S = a1 + a2 + b + c + d = 45 + 0 + 15 + 0 + 10 = 70. Based on the total index score, the hydrogen sulfide gas in the tunnel section DK16+150~+250 is determined to be at a high risk level.

[0055] In summary, this method was used to assess the hydrogen sulfide gas in the DK16+150~+250 section of the tunnel as a high-risk level, which is consistent with the findings from the on-site excavation.

[0056] Example 3 This embodiment uses the method of Example 1 to provide a classification method for the hydrogen sulfide gas hazard level in tunnels. Taking the D2K716+200~+500 section of a railway tunnel in Tibet as an example, the lithology near the tunnel is Triassic mudstone, sandstone interbedded with carbonaceous shale, with underdeveloped groundwater and geological structures. On-site excavation tests showed that the concentration of hydrogen sulfide hazard gas was 1.6~4.2ppm, and this section was judged to be a low-hazard area.

[0057] The rock type of a railway tunnel in Tibet, from D2K716+200 to +500, is shale rich in organic matter. The temperature is 26℃ and the burial depth is 650~680m. Let a1=30 and a2=2. The geological structure of the D2K716+200~+500 section of a railway tunnel in Tibet is underdeveloped, with c=0. In a railway tunnel in Tibet, groundwater is not well developed in the section from D2K716+200 to +500, and d=0. The tunnel section D2K716+200~+500 of a railway tunnel in Tibet consists of alternating layers of mudstone and sandstone, with e=4; The quantitative scores of the above four factors are summed to obtain S = a1 + a2 + b + c + d = 30 + 2 + 0 + 0 + 4 = 36. Based on the total index score, the hydrogen sulfide gas in the DK16+150~+250 section of the tunnel is determined to be of medium risk level.

[0058] In summary, this method was used to assess the hydrogen sulfide gas level in the DK16+150~+250 section of the tunnel as moderately hazardous, which is consistent with the findings from the on-site excavation.

[0059] Example 4 This embodiment provides a classification device for the hazard level of hydrogen sulfide gas in tunnels, including: The assessment module is used to establish assessment standard one based on the presence of sulfur-bearing strata and the temperature and pressure environment in the tunnel area. The second assessment module is used to establish assessment standard two based on the presence of structural fracture characteristics in the tunnel. The assessment module consists of three parts, which are used to establish assessment criteria three based on the development level and migration path of groundwater. The assessment module four is used to establish assessment standard four based on the lithology of the tunnel strata. The calculation module is used to calculate the risk index score based on the assessment scores obtained according to assessment criteria one, assessment criteria two, assessment criteria three, and assessment criteria four. The grading module is used to determine the hazard level of hydrogen sulfide gas in the tunnel based on the hazard index scores.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for classifying the hazard level of hydrogen sulfide gas in tunnels, characterized in that, Includes the following steps: An assessment standard was established based on the presence of sulfur-bearing strata and the temperature and pressure environment in the tunnel area. Evaluation Standard Two is established based on the presence of structural fractures in the tunnel. Assessment Standard Three is established based on the development level and migration pathways of groundwater; Evaluation Standard Four was established based on the lithology of the tunnel strata. The assessment scores obtained according to assessment criteria one, two, three, and four are used to calculate the hazard index score, and the hazard level of hydrogen sulfide gas in the tunnel is determined based on the hazard index score.

2. The method for classifying the hazard level of hydrogen sulfide gas in tunnels according to claim 1, characterized in that, The sulfur-bearing strata include sulfate rock strata, coal-bearing strata, oil and gas reservoirs, sulfur-bearing metal mineral anomaly zones, hot spring zones, organic-rich mudstone and shale strata, and gypsum-bearing carbonate rock strata. The temperature and pressure environment includes temperature and pressure. Scoring is performed based on the type of sulfur-bearing strata present in the tunnel area and the temperature and pressure environment of the tunnel area. The scores are then summed to obtain the evaluation score obtained according to evaluation standard one.

3. The method for classifying the hazard level of hydrogen sulfide gas in tunnels according to claim 2, characterized in that, Evaluation criterion one is: Regarding the presence of sulfur-bearing strata, if any of the following strata—sulfate rock strata, coal-bearing strata, or oil and gas reservoirs—are present along the tunnel axis and in the vicinity, the score is 50. When the underlying strata of the tunnel contain any one of the following types of strata: sulfate rock strata, coal-bearing strata, or oil and gas reservoirs, the score is 45. When the tunnel axis and the surrounding strata contain any of the following types of strata: sulfur-bearing metal mineral anomaly zone, hot spring zone, etc., the score is 40. When the underlying strata contain either a sulfur-bearing metal ore anomaly zone or a hot spring zone, the score is 35. When the tunnel axis and the surrounding strata contain either gypsum-bearing carbonate rock strata or organic-rich mudstone and shale strata, the score is 30. When the underlying strata of the tunnel contain either gypsum-bearing carbonate rock strata or organic-rich mudstone and shale strata, the score is 25; For the aforementioned temperature and pressure environment, when the temperature in and around the tunnel axis is >80℃ or the pressure is ≥3000m, the score is 5; When the temperature in the tunnel axis and nearby strata is 60℃≤temperature≤80℃ or 2000m≤pressure<3000m, the score is 4; When the tunnel axis and nearby strata have a temperature of 50℃≤Temperature<60℃ or a pressure of 1000m≤Pressure<2000m, the score is 3; When the temperature in and around the tunnel axis is between 37℃ and 50℃ or between 500m and 1000m, the score is 2. If the temperature in the tunnel axis and nearby strata is <37℃ or the pressure is <500m, the score is 0; When the temperature of the underlying strata is >80℃, the score is 4; When the underlying strata of the tunnel have a temperature of 60℃≤80℃, the score is 3; When the underlying strata of the tunnel have a temperature of 50℃≤Temperature<60℃, the score is 2; When the temperature of the underlying strata of the tunnel is 37℃≤Temperature<50℃, the score is 1; If the temperature of the underlying strata is <37℃, the score is 0.

4. The method for classifying the hazard level of hydrogen sulfide gas in tunnels according to claim 1, characterized in that, The tunnel's structural fracture characteristics were obtained through geophysical exploration methods, including seismic wave method and resistivity method.

5. The method for classifying the hazard level of hydrogen sulfide gas in tunnels according to claim 1, characterized in that, The tunnel structural fracture characteristics include faults, fold zones, fracture zones, and densely jointed zones. Scoring is based on the type of these fracture characteristics, with evaluation criterion two being: When there are faults in the tunnel axis and the underlying strata, the score is 25. When there are fold zones in and around the tunnel axis, the score is 20. When there is a fold zone in the underlying strata of the tunnel, the score is 15; When there are fracture zones and densely jointed zones in and around the tunnel axis, the score is 15. When there are fracture zones and dense joint zones in the underlying strata of the tunnel, the score is 10.

6. The method for classifying the hazard level of hydrogen sulfide gas in tunnels according to claim 1, characterized in that, The evaluation criteria are as follows: Scoring is based on the development level and migration path of groundwater in the tunnel. When there are stream-like water seepage along the tunnel axis and in the nearby strata, the score is 10; when there are sulfur-bearing strata beneath the tunnel and stream-like water seepage near the tunnel body, the score is 8. When there is rain-like to small-stream water discharge in and around the tunnel axis, the score is 8; when there is sulfur-bearing strata beneath the tunnel and rain-like to small-stream water discharge near the tunnel body, the score is 6. When there is damp to dripping water in the tunnel axis and nearby strata, the score is 4; when there is sulfur-bearing strata beneath the tunnel and there is damp to dripping water near the tunnel body, the score is 2. When the tunnel axis and the surrounding strata are dry and waterless, the score is 0.

7. The method for classifying the hazard level of hydrogen sulfide gas in tunnels according to claim 1, characterized in that, The tunnel strata lithology includes mudstone, dense limestone, mudstone interbedded with sandstone, and sandstone interbedded with mudstone. Scoring is based on the lithological types of the tunnel strata present in and around the tunnel body. Evaluation criterion four is as follows: When mudstone or dense limestone is present in the tunnel axis and nearby strata, the score is 10. When mudstone interbedded with sandstone exists in the tunnel axis and nearby strata, the score is 6; When there are alternating layers of mudstone and sandstone in and around the tunnel axis, the score is 4. When sandstone interbedded with mudstone exists in the tunnel axis and nearby strata, the score is 2; When sandstone or similar materials are present in the tunnel axis and nearby strata, the score is 0.

8. The method for classifying the hazard level of hydrogen sulfide gas in tunnels according to any one of claims 1-7, characterized in that, The assessment scores obtained according to assessment criteria one, two, three, and four are summed. The calculation method for the hazard index score is as follows: S = a + b + c + d S represents the risk index score, a represents the assessment score obtained according to assessment standard one, b represents the assessment score obtained according to assessment standard one, c represents the assessment score obtained according to assessment standard three, and d represents the assessment score obtained according to assessment standard four.

9. The method for classifying the hazard level of hydrogen sulfide gas in tunnels according to claim 8, characterized in that, Hydrogen sulfide gas is classified into four hazard levels, from low to high: low hazard, medium hazard, moderate hazard, and high hazard. The corresponding hazard index scores are S<40, 40≤S<60, 60≤S<80, and 80≤S<100, respectively.

10. A classification device for the hazard level of hydrogen sulfide gas in tunnels, characterized in that, include: The assessment module is used to establish assessment standard one based on the presence of sulfur-bearing strata and the temperature and pressure environment in the tunnel area. The second assessment module is used to establish assessment standard two based on the presence of structural fracture characteristics in the tunnel. The assessment module consists of three parts, which are used to establish assessment criteria three based on the development level and migration path of groundwater. The assessment module four is used to establish assessment standard four based on the lithology of the tunnel strata. The calculation module is used to calculate the risk index score based on the assessment scores obtained according to assessment criteria one, assessment criteria two, assessment criteria three, and assessment criteria four. The grading module is used to determine the hazard level of hydrogen sulfide gas in the tunnel based on the hazard index scores.

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