Coal mine goaf remediation method based on Internet of Things

Abstract

This invention belongs to the technical field of safety devices in mines or tunnels, specifically relating to a method for managing coal mine goaf areas based on the Internet of Things (IoT). The method includes the following steps: 1. Establishing a gas collection cavity: Excavating a gas collection cavity upwards at the elevation peak; 2. Installing gas collection grooves: Installing several gas collection grooves in the area between the top surface of the gas collection cavity and the tunnel floor. Each gas collection groove has a ventilation pipe installed at its top, and a gas sensor and a solenoid valve are installed on the exposed portion of the ventilation pipe; 3. Marking: Assigning location marking information to the gas sensor and solenoid valve on each ventilation pipe. Both the gas sensor and the solenoid valve are connected to a central control system, which is connected to an alarm module; 4. Connecting a gas extraction system: The gas extraction system's gas supply pipe is connected to the solenoid valve and the gas collection cavity. The gas extraction system is connected to the central control system. This invention solves the problem of goaf management when the tunnel floor elevation is close to the goaf elevation.

Description

Technical Field

[0001] This invention belongs to the technical field of safety devices in mines or tunnels, and specifically relates to a method for the treatment of coal mine goaf based on the Internet of Things. Background Technology

[0002] During the construction of railway tunnels, some sections need to pass over coal mine goaf areas. For example, the Chongqing-Qianjiang section of the railway passes through the Longqiao Coal Mine, which has ceased production, in the Zhengyang Town tunnel section. Most of the lower part of the tunnel has been mined, forming a goaf area. The elevation of the tunnel floor is close to the elevation of the goaf area, with an elevation difference of only a few meters. In order to ensure the safety of high-speed railway traffic, it is necessary to treat the goaf area within the affected area of ​​the corresponding tunnel section.

[0003] The rock strata in coal mine goaf areas are unstable, mainly consisting of mudstone and sandy mudstone. The surrounding rock near the goaf is mostly coal seam or coal gangue strata. Adjacent coal seams, unmined layers, and surrounding rock can all release gas into the goaf. If this gas enters the tunnel, it will seriously affect the safe operation of the railway tunnel. The conventional method for dealing with gas is backfilling and grouting. However, when the tunnel floor elevation is close to the goaf elevation, the low-frequency vibrations generated by train operation will cumulatively affect the underlying rock strata. Over time, this can easily lead to cracks in the rock strata, allowing gas to seep into the railway tunnel through these cracks, severely impacting train operation safety. Summary of the Invention

[0004] The present invention aims to provide a method for the treatment of coal mine goaf based on the Internet of Things, so as to solve the problem of goaf treatment when the elevation of the tunnel floor is close to the elevation of the coal mine goaf.

[0005] To achieve the above objectives, the present invention provides a method for the remediation of coal mine goaf areas based on the Internet of Things, comprising the following steps:

[0006] Roadway restoration: Restore existing transport roadways and existing return air roadways, and close other roadways more than 20 meters away from the boundary of the tunnel's vertical projection area;

[0007] Vertex detection: Detects the elevation vertex of the goaf directly beneath the tunnel, closest to the tunnel floor;

[0008] Set up a gas-gathering cavity: excavate a gas-gathering cavity with a depth of 0.5m to 2m and a minimum size of 1m × 1m at the elevation peak.

[0009] Ventilation holes are set up: Ventilation holes are drilled on the sidewall of the goaf at the elevation apex, with the holes inclined downwards and extending beyond the vertical projection area of ​​the tunnel;

[0010] Installation of gas collection troughs: Several gas collection troughs are installed in the area between the top surface of the gas collection cavity and the tunnel floor. A cavity is formed inside the gas collection trough. The side walls of the gas collection trough are sealed. A vent pipe is installed at the top of each gas collection trough. The vent pipe extends upward through the tunnel floor. A gas sensor and a solenoid valve are installed on the part of the vent pipe that is exposed in the tunnel.

[0011] Grouting: After the gas collection groove is installed, grout is injected into the rock strata below the tunnel floor and above the goaf.

[0012] Marking: Assign position marking information to the gas sensor and solenoid valve on each vent pipe. Both the gas sensor and solenoid valve are connected to the central control system, which is connected to the alarm module.

[0013] Connecting to the gas extraction system: The gas extraction system's gas supply pipe is connected to the solenoid valve and gas collection cavities, and the gas extraction system is connected to the central control system.

[0014] The working principle and beneficial effects of this solution are as follows:

[0015] Tunnel restoration: Transport tunnels are used to transport materials, equipment, and personnel needed for subsequent construction, while return air tunnels are used for ventilation. Both channels facilitate the accumulation of gas in gas cavities. Closing other tunnels prevents excessive gas accumulation in gas cavities, especially preventing gas from accumulating in gas cavities from areas too far beyond the area covered by the projection surface directly below the tunnel floor.

[0016] Peak detection: Methane gas is less dense than air, and when it is generated in a goaf, it tends to accumulate at the highest point.

[0017] Gas collection cavities are set up: Gas collection cavities are used to collect gas, and the gas is collected below the tunnel floor, which facilitates subsequent centralized extraction.

[0018] Vent holes are set up to guide the gas in the rock strata near the projection surface below the tunnel floor into the gas collection cavity. This area is close to the tunnel, and the gas generated can easily enter the tunnel along the gaps. The vent holes can guide the gas into the gas collection cavity.

[0019] Gas collection troughs are installed: Sealed gas collection troughs prevent gas leakage. Only vertically extending cracks can allow gas to leak into the tunnel. The installation of gas collection troughs serves two purposes: first, it blocks the vertical extension of cracks; second, even if cracks occur, gas will first enter the gas collection troughs, which collect the gas. This gas is then monitored by gas sensors exposed inside the tunnel. Since both the gas sensors and solenoid valves are electrical components, their installation in the tunnel isolates them from the gas environment. Therefore, they do not require intrinsically safe power supplies; conventional power supplies are sufficient, reducing costs. Opening the solenoid valves also allows the gas in the collection troughs to be extracted before entering the tunnel, preventing it from entering the tunnel.

[0020] Grouting: Grouting seals the cracks in the rock strata below the tunnel floor and above the goaf. This part is the thinnest rock stratum from the tunnel floor and is also the rock stratum most directly and severely affected by the low-frequency vibrations of train operation. Grouting in this area can achieve the most ideal treatment effect with the least amount of work and cost, and it is also convenient to set up grouting equipment inside the tunnel, which facilitates continued repair and treatment if cracks appear later.

[0021] Marking: When gas is detected, the central control system can accurately locate which area may have cracked based on the position marking information assigned to the gas sensor and solenoid valve on each vent pipe, and notify the relevant personnel through the alarm module so that the cracked area can be grouted again.

[0022] Connecting to the gas extraction system: When gas is detected, the central control system can automatically start the gas extraction system to remove the gas from the gas collection tank and gas collection cavity. This is more automated and avoids manual operation. Before grouting is required, personnel need to enter the corresponding area in the tunnel to work. The gas is removed before entering the work area, which helps to ensure the personal safety of the workers.

[0023] Optionally, the negative pressure ventilation system, drainage system, power supply system, lifting and transportation system, and personnel positioning system may be restarted.

[0024] Optionally, the length of the air vent extending beyond the vertical projection area of ​​the tunnel shall not be less than 20m.

[0025] Optionally, the gas collection slots are distributed in multiple layers, with each layer containing multiple gas collection slots, and the gas collection slots in adjacent layers are staggered.

[0026] Optionally, the method for burying the gas collection trough is as follows: the gas collection trough is precast with concrete, with one side of the gas collection trough open; the foundation pit is excavated from the bottom of the tunnel downwards, the distance between the bottom of the foundation pit and the top of the gas collection trough is not less than 1m, the bottom surface of the foundation pit is sealed with mortar, and then the gas collection trough is inverted on the bottom surface of the foundation pit with the open side facing down, and then the foundation pit is backfilled, and the backfill part is grouted.

[0027] Optionally, the bottom of the gas collection groove arches outward to form a circular arc surface.

[0028] Optionally, the top of the vent pipe is T-shaped, and a solenoid valve is installed at one end of the lateral end of the vent pipe. The other end of the lateral end of the vent pipe is covered with an end cap, and a one-way valve is fixed on the end cap. The one-way valve is connected to a return pipe with an outer diameter smaller than the inner diameter of the vent pipe. The return pipe is placed inside the vent pipe, and the end of the return pipe away from the one-way valve extends into the air collection groove.

[0029] Optionally, the steps also include:

[0030] Gas monitoring: The gas sensor detects the gas concentration in the corresponding vent pipe and determines whether the gas concentration exceeds the safe concentration range. If it does, an audible and visual alarm is issued, and an alarm message is generated and sent to the central control system. The alarm message includes the current gas concentration and location marker information.

[0031] Crack location: After receiving the alarm information, the central control system determines the location information of the gas sensor based on the location marker information, and sends the location information of the gas sensor and the current gas concentration to the alarm module.

[0032] Gas extraction: The alarm module receives confirmation information and sends it to the central control system. After receiving the confirmation information, the central control system determines the corresponding solenoid valve based on the location information of the gas sensor, controls the solenoid valve to open, and starts the gas extraction system to extract gas. The central control system obtains the current gas concentration from the gas sensor in real time and determines whether the current gas concentration is within the safe concentration range. If it is within the safe concentration range, it controls the solenoid valve to close and shuts down the gas extraction system.

[0033] Optionally, the steps also include:

[0034] Crack treatment: The gas sensor is located based on the audible and visual alarm, the location of the crack is determined, and grouting equipment is used to grout the location and surrounding area; the central control system determines whether the gas concentration at the location remains within the safe concentration range for a specified time. If it remains within the safe concentration range, the central control system sends a treatment completion message to the alarm module.

[0035] Optionally, during the gas monitoring process, if the gas concentration does not exceed the safe concentration range, the gas sensor sends the current gas concentration to the central control system at preset intervals. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of a coal mine goaf in an embodiment of the present invention;

[0037] Figure 2 This is a flowchart of a coal mine goaf remediation method based on the Internet of Things in an embodiment of the present invention. Detailed Implementation

[0038] The following detailed description illustrates the specific implementation method:

[0039] The markings in the accompanying drawings include: rock strata 1, tunnel 2, goaf 3, gas collection cavity 4, gas collection groove 5, ventilation pipe 6, air guide hole 7, and projection area 8.

[0040] Example

[0041] This embodiment is basically as shown in the appendix. Figure 1As shown, the method for remediating coal mine goaf based on the Internet of Things is as follows: Figure 2 As shown, the following steps are included:

[0042] Roadway restoration: Restore existing transport roadways and existing return air roadways, construct partition walls to seal off other roadways more than 20 meters away from the boundary of the vertical projection area 8 of tunnel 2, and also seal off the remaining parts of existing transport roadways and existing return air roadways except for those that ensure personnel and air can reach the elevation apex of goaf 3 with partition walls.

[0043] Vertex detection: The surveying team enters from the transport tunnel to detect the elevation vertex of the goaf 3, which is directly below tunnel 2 and closest to the bottom plate of tunnel 2, and marks the elevation vertex in a conspicuous manner with spray paint.

[0044] Restart and repair necessary maintenance systems: Restart and repair the negative pressure ventilation system, drainage system, power supply system, hoisting and transportation system, and personnel positioning system of the transport roadway and existing return air roadway from the entrance to the elevation peak.

[0045] Set up a gas collection cavity: The construction team enters and excavates a 10m×10m gas collection cavity 4 at the elevation peak.

[0046] Ventilation holes are set up: Ventilation holes 7 are drilled at an angle downwards on the side wall of the goaf 3 at the elevation apex using an explosion-proof rock drill. The ventilation holes 7 are distributed in an array and extend at least 50m outside the vertical projection area 8 of the tunnel 2.

[0047] Precast gas collection trough: A 3m×3m gas collection trough 5 is precast with concrete. One side of the gas collection trough 5 is open, and the bottom of the gas collection trough 5 is arched to the outside to form an arc surface. A cavity is formed inside the gas collection trough 5.

[0048] Installation of gas collection troughs: Several foundation pits are excavated from the bottom of Tunnel 2 downwards. The pits are of two different depths and are staggered. The distance between the bottom of the deepest pit and the top of the gas collection trough 4 is not less than 1m. The bottom of the pits is sealed with mortar. Then, the gas collection troughs 5 are placed upside down on the bottom of the pits. A through hole is made in the center of the top of each gas collection trough 5, and a vent pipe 6 is installed in the through hole. The vent pipe 6 penetrates the bottom slab of Tunnel 2 upwards. Then, the pits are backfilled, and the backfilled part is grouted. A gas sensor and a solenoid valve are installed on the part of the vent pipe 6 that protrudes from the tunnel 2. In this embodiment, the gas sensor is a fixed methane gas alarm (audible and visual alarm) of type LY851-CH4, which can not only detect gas, but also provide audible and visual alarms. The part of the vent pipe 6 that protrudes from the tunnel 2 is T-shaped. The solenoid valve is installed at one end of the lateral end of the vent pipe 6. The other end of the lateral end of the vent pipe 6 is covered with an end cap. A one-way valve is fixed on the end cap. The one-way valve is connected to a return gas pipe with an outer diameter smaller than the inner diameter of the vent pipe 6. The return gas pipe is placed inside the vent pipe 6. The end of the return gas pipe away from the one-way valve extends into the gas collection tank 5.

[0049] Grouting: After the gas collection trough 5 is installed, grout is injected into the rock stratum 1 below the bottom plate of tunnel 2 and above the goaf 3.

[0050] Marking: Assign position marking information to the gas sensor and solenoid valve on each vent pipe 6. Both the gas sensor and solenoid valve are connected to the central control system, which is connected to the alarm module, which is a mobile terminal.

[0051] Connecting the gas extraction system: The gas supply pipe of the gas extraction system is connected to the solenoid valve and the gas collection cavity 4. The gas extraction system is connected to the central control system. In this embodiment, the gas extraction system adopts a ground-fixed gas extraction pump station, which is set up in an open area.

[0052] Gas monitoring: The gas sensor detects the gas concentration in the corresponding ventilation pipe 6 and determines whether the gas concentration exceeds the safe concentration range. If it does, an audible and visual alarm is issued, and alarm information is generated and sent to the central control system. The alarm information includes the current gas concentration and location marker information. If the gas concentration does not exceed the safe concentration range, the gas sensor sends the current gas concentration to the central control system at preset intervals. In this embodiment, the preset interval is 5 minutes.

[0053] Crack location: After receiving the alarm information, the central control system determines the location information of the gas sensor based on the location marker information, and sends the location information of the gas sensor and the current gas concentration to the alarm module. The location marker information can be the device number or a custom location code, etc. For example, the device number can be associated with the actual installation location of the gas sensor and stored in the database. By using the device number, the associated actual installation location, i.e., the location information of the gas sensor, can be found in the database.

[0054] Gas extraction: The alarm module receives confirmation information and sends it to the central control system. After receiving the confirmation information, the central control system determines the corresponding solenoid valve based on the location information of the gas sensor, controls the solenoid valve to open, starts the pump station, and extracts gas. The central control system obtains the current gas concentration from the gas sensor in real time and determines whether the current gas concentration is within the safe concentration range. If it is within the safe concentration range, it controls the solenoid valve to close and shuts down the pump station.

[0055] Crack Treatment: Grouting personnel locate the gas sensor based on the audible and visual alarm, determine the location of the crack, and grout the location and surrounding area using grouting equipment. The central control system determines whether the gas concentration at the location remains within the safe range for a specified time. If it remains within the safe range, the central control system sends a treatment completion message to the alarm module; that is, treatment is complete, and personnel and grouting equipment can be withdrawn. In this embodiment, the specified time is 15 days.

[0056] Make full use of existing roadways and systems in the coal mine to ensure the entry and exit of equipment, personnel, and materials, and guarantee water supply, power supply, ventilation, and personnel positioning to ensure the safety of personnel operations. The elevation apex of the goaf 3, located directly below tunnel 2 and closest to the tunnel floor, was detected. Other unrelated roadways and areas were then sealed off. The main focus was on treating the area directly below and adjacent to tunnel 2, achieving the most ideal treatment effect with the lowest possible workload and cost.

[0057] Because methane gas is less dense than air, it tends to accumulate at higher elevations after being generated in goaf 3. Methane gas generated in the projected area 8 directly below tunnel 2 and within a radius of at least 50m around it is directed into goaf 3. This gas is then collected in a gas collection cavitation chamber 4 located at the elevation apex of goaf 3, and pumps are periodically activated for extraction.

[0058] For cracks that may be caused by train vibration, the two-layered staggered gas collection troughs 5 block the extension of vertical cracks. The blocked vertical cracks will appear on the bottom surface of the gas collection troughs 5, i.e., the bottom surface of the pit. Gas flowing through these cracks eventually enters the gas collection troughs 5. The gas diffuses through the ventilation pipe 6 to its top, where it is detected by a fixed methane gas alarm exceeding the safe concentration range. The fixed methane gas alarm emits an audible and visual alarm. The central control system detects the alarm signal from the fixed methane gas alarm, obtains its location marker information, and sends the location information to the alarm module, thus determining which area may have developed a crack. After monitoring personnel confirm the received information, the central control system automatically opens the solenoid valve and pump station on the corresponding ventilation pipe 6 to extract the gas. During the extraction process, air from tunnel 2 enters the gas collection troughs 5 through a one-way valve and a return pipe, balancing the gas pressure within the gas collection troughs 5 and reducing the gas concentration. During the extraction process, the methane gas concentration data is continuously monitored using a corresponding fixed methane gas alarm. Once the data drops to a safe level, the pump station and corresponding solenoid valves are shut down. The central control system continuously monitors the detection data from the fixed methane gas alarm. Grouting personnel enter Tunnel 2 with grouting equipment and quickly locate the fixed methane gas alarm based on its audible and visual alarm signals. This determines the approximate location of the crack. Grouting is then performed on the location and surrounding area. After observation, if the fixed methane gas alarm stops alarming within 15 days, the treatment is complete, and personnel and grouting equipment are withdrawn.

[0059] The above are merely embodiments of the present invention. The invention is not limited to the fields covered by these embodiments. Commonly known structures and characteristics in the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are able to access all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for coal mine goaf remediation based on the Internet of Things, characterized in that: Includes the following steps: Roadway restoration: Restore existing transport roadways and existing return air roadways, and close other roadways more than 20 meters away from the boundary of the tunnel's vertical projection area; Vertex detection: Detects the elevation vertex of the goaf directly beneath the tunnel, closest to the tunnel floor; Set up a gas-gathering cavity: excavate a gas-gathering cavity with a depth of 0.5m to 2m and a minimum size of 1m × 1m at the elevation peak. Ventilation holes are set up: Ventilation holes are drilled on the sidewall of the goaf at the elevation apex, with the holes inclined downwards and extending beyond the vertical projection area of ​​the tunnel; Installation of gas collection troughs: Several gas collection troughs are installed in the area between the top surface of the gas collection cavity and the tunnel floor. A cavity is formed inside the gas collection trough. The side walls of the gas collection trough are sealed. A vent pipe is installed at the top of each gas collection trough. The vent pipe extends upward through the tunnel floor. A gas sensor and a solenoid valve are installed on the part of the vent pipe that is exposed in the tunnel. Grouting: After the gas collection groove is installed, grout is injected into the rock strata below the tunnel floor and above the goaf. Marking: Assign position marking information to the gas sensor and solenoid valve on each vent pipe. Both the gas sensor and solenoid valve are connected to the central control system, which is connected to the alarm module. Connecting to the gas extraction system: The gas extraction system's gas supply pipe is connected to the solenoid valve and gas collection cavities, and the gas extraction system is connected to the central control system.

2. The method for coal mine goaf remediation based on the Internet of Things according to claim 1, characterized in that: Restart the negative pressure ventilation system, drainage system, power supply system, lifting and transportation system, and personnel positioning system.

3. The method for coal mine goaf remediation based on the Internet of Things according to claim 2, characterized in that: The length of the air vent extending beyond the vertical projection area of ​​the tunnel shall not be less than 20m.

4. The method for coal mine goaf remediation based on the Internet of Things according to claim 3, characterized in that: The gas collection slots are distributed in multiple layers, with each layer containing multiple gas collection slots, and the gas collection slots in adjacent layers are staggered.

5. The method for coal mine goaf remediation based on the Internet of Things according to claim 4, characterized in that: The method for installing the gas collection trough is as follows: the gas collection trough is precast with concrete, with one side of the gas collection trough open; the foundation pit is excavated from the bottom of the tunnel downwards, with the distance between the bottom of the foundation pit and the top of the gas collection trough not less than 1m. The bottom surface of the foundation pit is sealed with mortar, and then the gas collection trough is inverted on the bottom surface of the foundation pit with the open side facing down. Then the foundation pit is backfilled, and the backfill part is grouted.

6. The method for coal mine goaf remediation based on the Internet of Things according to claim 5, characterized in that: The top of the gas collection trough arches outward to form a circular arc surface.

7. The method for coal mine goaf remediation based on the Internet of Things according to claim 6, characterized in that: The top of the vent pipe is T-shaped. A solenoid valve is installed at one end of the vent pipe's horizontal end. The other end of the vent pipe's horizontal end is covered with an end cap. A one-way valve is fixed on the end cap. The one-way valve is connected to a return pipe with an outer diameter smaller than the inner diameter of the vent pipe. The return pipe is placed inside the vent pipe, and the end of the return pipe away from the one-way valve extends into the air collection groove.

8. The method for coal mine goaf remediation based on the Internet of Things according to claim 1, characterized in that: It also includes the following steps: Gas monitoring: The gas sensor detects the gas concentration in the corresponding vent pipe and determines whether the gas concentration exceeds the safe concentration range. If it does, an audible and visual alarm is issued, and an alarm message is generated and sent to the central control system. The alarm message includes the current gas concentration and location marker information. Crack location: After receiving the alarm information, the central control system determines the location information of the gas sensor based on the location marker information, and sends the location information of the gas sensor and the current gas concentration to the alarm module. Gas extraction: The alarm module receives confirmation information and sends it to the central control system. After receiving the confirmation information, the central control system determines the corresponding solenoid valve based on the location information of the gas sensor, controls the solenoid valve to open, and starts the gas extraction system to extract gas. The central control system obtains the current gas concentration from the gas sensor in real time and determines whether the current gas concentration is within the safe concentration range. If it is within the safe concentration range, it controls the solenoid valve to close and shuts down the gas extraction system.

9. The method for coal mine goaf remediation based on the Internet of Things according to claim 8, characterized in that: It also includes the following steps: Crack treatment: The gas sensor is located based on the audible and visual alarm, the location of the crack is determined, and grouting equipment is used to grout the location and surrounding area; the central control system determines whether the gas concentration at the location remains within the safe concentration range for a specified time. If it remains within the safe concentration range, the central control system sends a treatment completion message to the alarm module.

10. The method for coal mine goaf remediation based on the Internet of Things according to claim 8, characterized in that: During the gas monitoring process, if the gas concentration does not exceed the safe concentration range, the gas sensor sends the current gas concentration to the central control system at preset intervals.

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