A method for identifying and controlling coal spontaneous combustion and gas co-existence disasters in overlapping goaf areas

Abstract

This invention discloses a method for identifying and controlling coal spontaneous combustion and gas coexistence disasters in overlapping goaf areas. It can accurately determine the approximate extent of the goaf area by combining geological data, transient electromagnetic detection devices, and borehole inspection instruments. A specific algorithm is used to calculate the pore dimension and average porosity of the area. Then, multiple detection holes are arranged at different angles around the grouting hole, forming a spherical outward diffusion pattern. A comprehensive monitoring device is installed at the end of each detection hole to obtain data on underground gas concentration, temperature, pressure, air leakage, and geostress fields to determine if any anomalies exist. The redundant or complementary information from multiple monitoring devices in different locations, both spatially and temporally, provides a relatively complete and consistent interpretation or description of the goaf area, enabling more accurate identification and judgment of disaster situations and ensuring construction safety throughout the entire tunneling or mining process.

Description

Technical Field

[0001] This invention relates to a method for identifying and controlling coal spontaneous combustion and gas coexistence disasters in overlapping goaf areas. Specifically, it is a method for accurately identifying and efficiently controlling coal spontaneous combustion and gas disasters induced by air leakage due to fissures during roadway excavation and working face mining operations in areas near overlapping goaf areas. This invention belongs to the field of coal mine disaster prevention and control technology. Background Technology

[0002] Coal is an important fossil fuel. In recent years, with the increasing demand for coal resources, the scale and difficulty of coal mining have continued to expand, posing enormous challenges to safe production. Frequent gas explosions and other disasters in coal mines greatly affect the stable and healthy operation of coal mining enterprises and are also a major factor restricting the development of the coal industry.

[0003] The combined disaster of spontaneous combustion of coal and gas in goaf is caused by the convergence of multiple media, including the fracture field, CH4 volume fraction field, O2 volume fraction field, and temperature field. In the convergence of these multiple fields within the fracture space, spontaneous combustion of coal, gas combustion, and gas explosion coexist and influence each other, exhibiting a strong dynamic coupling effect. For overlapping goaf areas or goaf areas with thick coal seams requiring multi-layer mining, after the upper layer of coal is mined, there is less residual coal in the goaf, the degree of coal fragmentation is low, and the probability of spontaneous combustion is low. However, when the lower layer is mined, it is essentially equivalent to intervening in the lower part of the goaf. Due to factors such as dip angle or incoming pressure, the coal seam is exposed again, causing the upper and lower goaf areas to connect. Under continuous air leakage, the floating coal and residual coal in the goaf accelerate heating and oxidation, and spontaneous combustion of coal under suitable oxygen supply and heat storage conditions becomes a high-temperature "ignition source" for gas disasters. Furthermore, the goaf area of ​​the mining face is a semi-enclosed space composed of a large amount of broken rock and residual coal. If the mining process encounters faults, roadway rock bursts, or other factors that slow down the advance speed of the working face, due to the difference in gas pressure between the upper and lower layers, a large amount of gas will rush into the upper layer at the moment of connection between the upper and lower layers. This will cause the residual gas in the upper layer of residual coal to continuously desorb and diffuse from the floor cracks into the working face of the lower layer of coal seam being mined, resulting in an increase in the gas and oxygen concentration in the lower layer. Ultimately, this will accelerate the oxidation rate of the residual coal in the goaf area, making it prone to coal spontaneous combustion and gas co-occurrence disasters.

[0004] To effectively prevent and control the combined disasters of coal spontaneous combustion and gas in goaf areas, scholars both domestically and internationally have adopted a coordinated approach involving oxygen control, gas control, temperature control, and time control. This primarily involves implementing "extraction-sealing-injection-grouting" measures, such as gas extraction and the injection of non-combustible materials, to ensure the safe mining of coal resources where gas and coal spontaneous combustion coexist. Currently, Chinese invention patent CN117005911A discloses a method and device for monitoring and early warning of combined disasters in deep coal mining. It mainly combines a pre-set evaluation system to dynamically couple and analyze disaster monitoring geospatial physical quantity data and disaster monitoring geospatial temporal measurement data within the scope of disaster monitoring geospatial geometric data to obtain real-time early warning information. However, it only considers geological factors and is not comprehensive enough. Chinese invention patent CN111425245A discloses a method for preventing coal-gas symbiotic disasters based on optimizing the ventilation field in the goaf. This method primarily determines a reasonable negative pressure for extraction in the coal seam, optimizes the ventilation field in the goaf, and thus ensures effective gas extraction while preventing coal-gas symbiotic disasters. Chinese invention patent CN108959691A discloses a method for determining dynamic isolation parameters for coupled disasters in high-gas, spontaneously combustible goafs. This method mainly uses the distribution law of porosity behind the goaf to simulate the flow field, thereby determining the optimal isolation parameters. However, due to the concealed, coupled, dynamic, and complex nature of coal spontaneous combustion and gas symbiotic disasters, the aforementioned prevention and control methods only address some aspects of these disasters through monitoring and management, and the research system is still incomplete.

[0005] In summary, current methods for identifying and managing coal spontaneous combustion and gas combined disasters are not systematic enough. To prevent the continuous deterioration of coal spontaneous combustion and gas combined disasters caused by the mutual influence between various disaster types, the dynamic changes in the coexisting environment of goaf areas, the disaster-causing evolution due to nonlinear heating in goaf areas, and the inability to accurately observe changes in fires within goaf areas, a multidisciplinary and multi-method integrated approach is needed. This approach aims to achieve accurate prediction and assessment of the disaster risk caused by coal spontaneous combustion and gas combined disasters in goaf areas, accurate acquisition of disaster information, rational selection of closed areas, and precise location and intelligent targeted treatment of disaster areas. This will provide key technical support for effectively avoiding the occurrence of combined disasters.

[0006] Therefore, this invention proposes a method that can accurately determine whether the surrounding gas concentration field, temperature field, gas pressure field, air leakage flow field, and ground stress field are abnormal by comprehensively considering multiple factors such as the concentration of harmful gases, gas pressure, temperature, ground stress, and air leakage. By taking different solutions for the abnormal phenomena, this method provides technical support for the accurate identification and efficient management of coal spontaneous combustion and gas disasters in goaf areas, which is the research direction of this invention. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a method for identifying and controlling coal spontaneous combustion and gas coexistence disasters in overlapping goaf areas, which can effectively solve the above-mentioned technical problems.

[0008] To achieve the above objectives, the technical solution adopted by this invention is: a method for identifying and controlling coal spontaneous combustion and gas coexistence disasters in overlapping goaf areas, the specific steps of which are as follows:

[0009] A. Before tunneling, advance drilling is carried out in front of the tunnel according to the construction design drawings to determine whether there is a goaf ahead. If no goaf is found, the tunnel is started to be excavated to the detection distance of the advance drilling and then stopped. The advance drilling is continued from the current position to determine whether there is a goaf ahead. This process is repeated until a goaf is determined to exist. Then, proceed to step B.

[0010] B. A transient electromagnetic detection device is inserted into the pre-drill hole to determine the specific location and shape of the goaf, and to determine the porosity within the goaf, thereby determining the range that needs to be reinforced and the water-cement ratio and dosage of the paste quick-setting material.

[0011] C. Use the pre-drilled holes as grouting holes, and grout different areas of the goaf ahead according to the water-cement ratio and dosage of the paste quick-setting material calculated in step B.

[0012] D. After the grout solidifies, multiple detection holes are set up around the grouting hole as the center, and a comprehensive monitoring device is placed at the end position of each detection hole to obtain the monitoring data around the end of each detection hole in real time.

[0013] E. During the tunneling and mining process, staff regularly record the monitoring data of each probe hole and upload it to the data terminal in a timely manner. The data terminal analyzes the monitoring data to determine whether there are any abnormalities around the final hole of each probe hole. If an abnormality is found, an early warning is issued to stop construction. At the same time, the abnormal area is quickly located based on the location of the probe hole where the abnormality is found, and the degree of danger is determined in combination with the monitoring data. Then, corresponding treatment measures are taken according to the degree of danger to reduce the probability of disaster.

[0014] F. After the disaster is treated, continue to use each detection hole to obtain corresponding monitoring data. If no abnormality is found during the monitoring period, continue to excavate the tunnel for a certain distance and repeat steps A to E to continue the advanced detection process for the next section. If an abnormality is found during the monitoring period, repeat step E to determine the degree of danger of the abnormality and take corresponding treatment measures until the monitoring data returns to normal, and then continue to excavate the tunnel.

[0015] Furthermore, the specific process of determining the goaf in step A is as follows: during the drilling of the advance borehole, the presence of a goaf ahead is determined by comprehensively considering multiple factors such as the water inflow of the drill bit, the advance speed, and the resistance encountered during the advance.

[0016] Furthermore, the specific process for determining porosity in step B is as follows: based on the measured location and shape of the goaf, multiple borehole inspection instruments are inserted into the goaf to capture images. The images acquired by each borehole inspection instrument are then unfolded to obtain a panoramic view. The images are processed using binarization and grayscale methods, respectively, and different side lengths δ are used. k The boxes cover the matrix region in the image, and the required number of boxes N is counted. δk Then, the least squares method is used to analyze the series of data points (-lgδ). k ,lgN δk Perform linear fitting to obtain the equation of the fitted line: lgN δk =D B ×(-lg δk )+b, and then the fractal dimension D of the pores is calculated. B Therefore, porosity is expressed as: Where r min and r max These are the minimum and maximum radii of the pore channel, D. B It is the fractal dimension of the pore size, where 0 < D in two-dimensional space. B <2, 0 <D B <3.

[0017] Furthermore, in step B, determining the water-cement ratio and dosage of the paste-based quick-setting material is as follows: the porosity of the goaf is not uniformly distributed. The porosity of similar goaf areas is classified. By classifying the porosity of different regions, and combining the size of the porosity, as well as the fluidity and mechanical strength of the paste-based quick-setting material, the dosage of the paste-based quick-setting material is calculated using the following formula.

[0018] Slurry diffusion radius:

[0019]

[0020] In the formula, P1 is the grouting pressure, P0 is the groundwater pressure, μ is the ratio of the grout viscosity to the water viscosity, and θ is the angle between the central axis of the grouting hole and the vertical line. Porosity of porous media To initiate the pressure gradient, t is the grouting time, K is the permeability coefficient, R is the grout diffusion radius after time t, and r is the grouting hole radius;

[0021] Grouting volume:

[0022] Q = A·L·π·R 2 ·e c ·β

[0023] In the formula, A is the grout loss coefficient; L is the grouting hole length; R is the grout diffusion radius; e c β represents the average porosity of the rock; β is the grout filling coefficient.

[0024] Furthermore, in step D, each detection hole is centered on the grouting hole, and its distribution is spherical at different angles, continuously spreading outward from the grouting hole, used to monitor the situation throughout the entire tunneling or mining process; the integrated monitoring device includes a bundled tube monitor, thermocouples or high-sensitivity optical fibers, ground stress plates, U-tubes or micromanometers, and hot-wire anemometers, used to acquire data on gas concentration field, temperature field, gas pressure field, air leakage flow field, and ground stress field.

[0025] Furthermore, step E specifically involves: observing whether the data on gas concentration field, temperature field, gas pressure field, air leakage flow field, and ground stress field are abnormal; and simultaneously, by combining the data, taking corresponding processing measures, as follows:

[0026] (1) When abnormalities occur in the temperature field and gas concentration field, the following countermeasures shall be taken:

[0027]

[0028] (2) When the local stress field is abnormal, that is, the stress detected by the pressure plate after grouting is less than the stress borne by the rock mass itself, it indicates that the grouting material may still break, and a paste-like quick-setting material with stronger bearing capacity should be continued to be filled into the interior.

[0029] (3) When the gas pressure field and leakage flow field are abnormal, the drilling excavation will cause stress redistribution, and the coal body around the borehole will be subjected to stress changes similar to those caused by roadway excavation. The dual disturbance will aggravate the damage to the coal body, the development of fractures will reach maturity, the air flow in the field will be abnormal, and the coal seam will be provided with a continuous oxygen supply, which will make it easier for coal to spontaneously combust. At this time, SF6 gas is used for tracer marking. New boreholes are drilled around the current abnormal detection hole or SF6 is released at a constant flow rate at adjacent detection holes. Under negative pressure extraction conditions, the tracer gas mixes with the roadway air under negative pressure and diffuses to the extraction borehole. After a period of time, the tracer gas will be evenly distributed in the abnormal detection hole. Then, a portable gas detector is used to detect whether there is air leakage. The borehole leakage rate is calculated by the distance between the release point and the receiving point and the time difference between the release of SF6 and the detection of SF6. When the leakage rate is greater than the threshold, grouting process is carried out in time.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] ① This invention can accurately determine the approximate extent of the goaf area by combining geological data, transient electromagnetic detection devices, and borehole inspection instruments. It can also observe the changes in resistivity in the terrain ahead and accurately determine the morphological characteristics of underground geological anomalies through the detection of transient electromagnetic detection devices. Furthermore, by using a borehole inspection instrument to explore forward until reaching the goaf area, the images captured by the borehole inspection instrument can be processed using binarization, grayscale specification, and difference algorithms to convert the three-dimensional image into a one-dimensional plane, thereby better calculating the pore dimension and average porosity of the area. This effectively avoids the drawbacks of manual excavation, such as omissions and large workload, and ensures safe mining.

[0032] ② This invention uses the grouting hole as the center and arranges multiple detection holes at different angles. Each detection hole faces different directions, forming a spherical distribution that continuously diffuses outwards. By deploying a comprehensive monitoring device at the end of each detection hole, it obtains data on the underground gas concentration field, temperature field, gas pressure field, air leakage flow field, and ground stress field to determine if there are any anomalies. The redundant or complementary information from multiple monitoring devices in different locations in space or time provides a relatively complete and consistent interpretation or description of the goaf as a whole, thereby enabling more accurate identification and judgment of disaster situations and ensuring construction safety throughout the entire tunneling or mining process.

[0033] ③ This invention addresses the complexity, suddenness, dynamism, and coupling characteristics of coal spontaneous combustion and gas symbiotic disasters in overlapping goaf areas by adopting a prevention and control method of identification followed by treatment. The data processing center integrates geological data from the mining of the upper goaf area of ​​the coal mine, the sensing data from the monitoring devices buried in the detection holes, and the detection data from the borehole inspection instrument. This allows it to determine the distribution of the fracture field, gas concentration field, temperature field, gas pressure field, and ground stress distribution field in front of and above the tunnel. Finally, it comprehensively considers and analyzes the changes in the abnormal fields and selects the corresponding treatment method according to the situation to achieve more accurate prevention of symbiotic disasters after grouting.

[0034] ④ This invention combines underground equipment and software monitoring systems with theoretical and field conditions, reducing the shortcomings of traditional coal spontaneous combustion monitoring in goaf areas, such as numerous blind spots, poor timeliness, and high false alarm rates, and greatly improving the ability of underground proactive disaster prevention and mitigation. Attached Figure Description

[0035] Figure 1 This is an overall flowchart of the present invention;

[0036] Figure 2 This is a schematic diagram of the drilling process of the present invention;

[0037] Figure 3 This is a schematic diagram showing the placement angle of the transient electromagnetic detection construction frame in this invention;

[0038] Figure 4 This is a schematic diagram of the drilling in the horizontal direction of the probe hole in this invention;

[0039] Figure 5 This is a schematic diagram of the drilling in the vertical direction of the probe hole in this invention. Detailed Implementation

[0040] The present invention will be further described below.

[0041] like Figure 1 As shown, the specific steps of this invention are as follows:

[0042] A. Before tunneling, advance drilling is carried out ahead of the tunnel according to the construction design drawings. During the advance drilling process, the presence of a goaf is determined by a combination of factors, including the water flow of the drill bit, the advance speed, and the resistance encountered during the advance. If no goaf is found, the tunneling is stopped after reaching the detection distance of the advance drilling, and the advance drilling continues from the current position to determine if a goaf is found. This process is repeated until a goaf is found, at which point step B is initiated.

[0043] B. A transient electromagnetic detection device is inserted into the advance borehole to determine the specific location and shape of the goaf, and to determine the porosity within the goaf. Figure 2 and 3 As shown, the specific process is as follows: Based on the determined location and shape of the goaf, multiple borehole inspection instruments are sent into the goaf to capture images. The images acquired by each borehole inspection instrument are then unfolded to obtain a panoramic view. The images are processed using binarization and grayscale methods, respectively, and different side lengths δ are used. k The boxes cover the matrix region in the image, and the required number of boxes N is counted. δk Then, the least squares method is used to analyze the series of data points (-lgδ). k ,lgN δk Perform linear fitting to obtain the equation of the fitted line: lgN δk =D B ×(-lg δk )+b, and then the fractal dimension D of the pores is calculated. B Therefore, porosity is expressed as: Where r min and r max These are the minimum and maximum radii of the pore channel, D. B It is the fractal dimension of the pore size, where 0 < D in two-dimensional space. B <2, 0 <D B <3;

[0044] Determine the scope requiring reinforcement and the water-cement ratio and dosage of the paste-based quick-setting material. Specifically: the porosity of the goaf is not uniformly distributed. The porosity of similar goaf areas is classified. By classifying the porosity of different areas, and combining the size of the porosity, as well as the fluidity and mechanical strength of the paste-based quick-setting material, the dosage of the paste-based quick-setting material is calculated using the following formula.

[0045] Slurry diffusion radius:

[0046]

[0047] In the formula, P1 is the grouting pressure, P0 is the groundwater pressure, μ is the ratio of the grout viscosity to the water viscosity, and θ is the angle between the central axis of the grouting hole and the vertical line. Porosity of porous media To initiate the pressure gradient, t is the grouting time, K is the permeability coefficient, R is the grout diffusion radius after time t, and r is the grouting hole radius;

[0048] Grouting volume:

[0049] Q = A·L·π·R 2 ·e c ·β

[0050] In the formula, A is the grout loss coefficient; L is the grouting hole length; R is the grout diffusion radius; e c β represents the average porosity of the rock; β is the grout filling coefficient.

[0051] C. Use the pre-drilled holes as grouting holes, and grout different areas of the goaf ahead according to the water-cement ratio and dosage of the paste quick-setting material calculated in step B.

[0052] D. After the grout solidifies, the distribution of each probe hole, centered on the grouting hole, is spherical at different angles, continuously expanding outwards from the grouting hole. Adjacent probe holes are spaced 1-2 meters apart horizontally, and each probe hole faces a different direction. Figure 4 and 5 As shown, a comprehensive monitoring device is placed at the end position of each detection hole to monitor the situation throughout the entire tunneling or mining process; the comprehensive monitoring device includes a bundled tube monitor, thermocouples or high-sensitivity optical fibers, ground stress plates, U-tubes or micro-manometers and hot-wire anemometers to acquire data on gas concentration field, temperature field, gas pressure field, air leakage flow field and ground stress field.

[0053] E. During tunneling and mining, staff regularly record and promptly upload monitoring data from each probe borehole to the data terminal. The data terminal analyzes the monitoring data to determine if there are any anomalies around the final borehole of each probe. If an anomaly is detected, an early warning is issued to stop construction. Simultaneously, the location of the anomaly is quickly pinpointed based on the location of the detected borehole, and the degree of danger is assessed in conjunction with the monitoring data. Corresponding measures are then taken based on the degree of danger to reduce the probability of disaster. Specifically, this involves observing whether there are anomalies in the gas concentration field, temperature field, gas pressure field, air leakage flow field, and ground stress field data. Furthermore, by combining the data, corresponding measures are taken as follows:

[0054] (1) When abnormalities occur in the temperature field and gas concentration field, the following countermeasures shall be taken:

[0055]

[0056] (2) When the local stress field is abnormal, that is, the stress detected by the pressure plate after grouting is less than the stress borne by the rock mass itself, it indicates that the grouting material may still break, and a paste-like quick-setting material with stronger bearing capacity should be continued to be filled into the interior.

[0057] (3) When the gas pressure field and leakage flow field are abnormal, the drilling excavation will cause stress redistribution, and the coal body around the borehole will be subjected to stress changes similar to those caused by roadway excavation. The dual disturbance will aggravate the damage to the coal body, the development of fractures will reach maturity, the air flow in the field will be abnormal, and the coal seam will be provided with a continuous oxygen supply, which will make it easier for coal to spontaneously combust. At this time, SF6 gas is used for tracer marking. New boreholes are drilled around the current abnormal detection hole or SF6 is released at a constant flow rate at adjacent detection holes. Under negative pressure extraction conditions, the tracer gas mixes with the roadway air under negative pressure and diffuses to the extraction borehole. After a period of time, the tracer gas will be evenly distributed in the abnormal detection hole. Then, a portable gas detector is used to detect whether there is air leakage. The borehole leakage rate is calculated by the distance between the release point and the receiving point and the time difference between the release of SF6 and the detection of SF6. When the leakage rate is greater than the threshold, grouting process is carried out in time.

[0058] F. After the disaster is treated, continue to use each detection hole to obtain corresponding monitoring data. If no abnormality is found during the monitoring period, continue to excavate the tunnel for a certain distance and repeat steps A to E to continue the advanced detection process for the next section. If an abnormality is found during the monitoring period, repeat step E to determine the degree of danger of the abnormality and take corresponding treatment measures until the monitoring data returns to normal, and then continue to excavate the tunnel.

[0059] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for identifying and controlling the symbiotic disaster of spontaneous combustion of coal and gas in overlapping goaf areas, characterized in that, The specific steps are: A. Before tunneling, advance drilling is carried out in front of the tunnel according to the construction design drawings to determine whether there is a goaf ahead. If no goaf is found, the tunnel is started to be excavated to the detection distance of the advance drilling and then stopped. The advance drilling continues from the current position to the front, and the goaf is determined to be present. This process is repeated until a goaf is determined to exist. Then, proceed to step B. B. A transient electromagnetic detection device is inserted into the advance borehole to determine the specific location and shape of the goaf and to determine the porosity within the goaf. The specific process is as follows: Based on the determined location and shape of the goaf, multiple borehole inspection instruments are inserted into the goaf to capture images. The images acquired by each borehole inspection instrument are then unfolded to obtain a panoramic view. The images are processed using binarization and grayscale methods, respectively, using different side lengths δ. k The boxes cover the matrix region in the image, and the required number of boxes N is counted. δk Then, the least squares method is used to analyze the series of data points (-lgδ). k ,lgN δk Perform linear fitting to obtain the equation of the fitted line: lgN δk =D B ×(-lg δk )+b, and then the fractal dimension D of the pores is calculated. B Therefore, porosity is expressed as: Where r min and r max These are the minimum and maximum radii of the pore channel, D. B It is the fractal dimension of the pore size; Then, the scope of reinforcement and the water-cement ratio and dosage of the paste quick-setting material are determined. Specifically, since the porosity of the goaf is not uniformly distributed, the porosity of similar goaf areas is classified. By classifying the porosity of different areas, and combining the size of the porosity, the fluidity and mechanical strength of the paste quick-setting material, the dosage of the paste quick-setting material is calculated using the following formula. Slurry diffusion radius: In the formula, P1 is the grouting pressure, P0 is the groundwater pressure, μ is the ratio of the grout viscosity to the water viscosity, and θ is the angle between the central axis of the grouting hole and the vertical line. Where φ is the porosity of the porous medium, φ is the starting pressure gradient, t is the grouting time, K is the permeability coefficient, R is the grout diffusion radius after time t, and r is the radius of the grouting hole. Grouting volume: Q=A·L·π·R 2 ·e c ·b; In the formula, A is the grout loss coefficient; L is the grouting hole length; R is the grout diffusion radius; e c β is the average porosity of the rock; β is the grout filling coefficient. C. Use the pre-drilled holes as grouting holes, and grout different areas of the goaf ahead according to the water-cement ratio and dosage of the paste quick-setting material calculated in step B. D. After the grout solidifies, a comprehensive monitoring device is placed at the final position of each detection hole. Each detection hole, centered on the grouting hole, is spherically distributed at different angles, continuously expanding outwards from the grouting hole. This device is used to acquire real-time monitoring data around the final position of each detection hole, monitoring the entire tunneling or mining process. The comprehensive monitoring device includes a bundled tube monitor, thermocouples or high-sensitivity optical fibers, a ground stress plate, a U-tube or micromanometer, and a hot-wire anemometer, used to acquire data on gas concentration field, temperature field, gas pressure field, air leakage flow field, and ground stress field. E. During tunneling and mining, staff regularly record and promptly upload monitoring data from each probe borehole to the data terminal. The data terminal analyzes the monitoring data to determine if there are any anomalies around the final borehole of each probe. If an anomaly is detected, an early warning is issued to stop construction. Simultaneously, the location of the anomaly is quickly pinpointed based on the location of the detected borehole, and the degree of danger is assessed in conjunction with the monitoring data. Corresponding measures are then taken based on the degree of danger to reduce the probability of disaster. Specifically, this involves observing whether there are anomalies in the gas concentration field, temperature field, gas pressure field, air leakage flow field, and ground stress field data. Furthermore, by combining the data, corresponding measures are taken as follows: (1) When abnormalities occur in the temperature field and gas concentration field, the following countermeasures shall be taken: (2) When the local stress field is abnormal, the stress detected by the pressure plate after grouting is less than the stress borne by the rock mass itself, indicating that the grouting material may still break, and a paste-like quick-setting material with stronger bearing capacity should be continued to be filled into the interior. (3) When the gas pressure field and leakage flow field are abnormal, the drilling excavation will cause stress redistribution, and the coal body around the borehole will be affected by the stress changes caused by the roadway excavation. The dual disturbance will aggravate the damage to the coal body, the development of the fracture will reach maturity, the air flow in the field will be abnormal, and the coal seam will be provided with a continuous oxygen supply, which will make the coal more likely to spontaneously combust. At this time, SF6 gas is used for tracer marking. New boreholes are drilled around the current abnormal detection hole or SF6 is released at a constant flow rate at adjacent detection holes. Under negative pressure extraction conditions, the tracer gas mixes with the roadway air under negative pressure and diffuses to the extraction borehole. After a period of time, the tracer gas will be evenly distributed in the abnormal detection hole. Then, a portable gas detector is used to detect whether there is air leakage. The borehole leakage rate is calculated by the distance between the release point and the receiving point and the time difference between the release of SF6 and the detection of SF6. When the leakage rate is greater than the threshold, grouting process is carried out in time. F. After the disaster is treated, continue to use each detection hole to obtain corresponding monitoring data. If no abnormality is found during the monitoring period, continue to excavate the tunnel for a certain distance and repeat steps A to E to continue the advanced detection process for the next section. If an abnormality is found during the monitoring period, repeat step E to determine the degree of danger of the abnormality and take corresponding treatment measures until the monitoring data returns to normal, and then continue to excavate the tunnel.

2. The method for identifying and controlling coal spontaneous combustion and gas coexistence disasters in overlapping goaf areas according to claim 1, characterized in that, The specific process for determining the goaf in step A is as follows: during the drilling process of the advanced borehole, the presence of a goaf ahead is determined by comprehensively considering multiple factors such as the water inflow of the drill bit, the advance speed, and the resistance encountered during the advance.

Images