Ventilation method for long distance tunneling working face

Abstract

The invention discloses a ventilation method for a long-distance tunnel excavation working face, which comprises: before tunnel mining, drilling an L-shaped horizontal well at a selected well position, installing extraction equipment on the ground, and pre-extracting gas from a main mining coal seam through the L-shaped horizontal well; before tunnel mining, utilizing the L-shaped horizontal well used for ground gas extraction when the coal seam is not mined as a return air channel for the tunneling tunnel, and when the coal seam is mined to the control range of the L-shaped horizontal well, maintaining the tunneling direction consistent with the horizontal section of the L-shaped horizontal well; during tunnel mining, connecting the ventilation equipment to the tunneling face for pressure ventilation, and simultaneously utilizing the ground gas extraction equipment to perform auxiliary negative pressure ventilation on the tunneling working face through the horizontal section of the L-shaped horizontal well, thereby achieving multiple uses of one hole, thereby overcoming the current status of dust control, air volume loss, and high ventilation energy consumption during ventilation of long-distance tunneling tunnels.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel mining, and in particular to a ventilation method for a long-distance tunnel excavation working face. Background Art

[0002] Coal tunneling is an important link in the succession of mining and excavation in mines, and is a basic technical link to ensure the efficient production of mines. Factors such as gas outburst and dust generated during the tunneling process seriously affect the safe and efficient tunneling of coal tunnels. Since the ventilation of a single tunnel cannot form an independent ventilation system during tunneling, local fan ventilation and wind duct air guidance are generally required to achieve local ventilation of the tunneling face to solve disasters such as gas and dust in the tunnel, provide a good climate environment for the working face personnel, and ensure safe production. In related technologies, in long-distance ventilation, since both wind pressure and wind resistance increase with the increase of ventilation distance, the fan wind pressure, wind duct wind resistance and air leakage rate are all affected by the distance. The longer the ventilation distance, the greater the difficulty of ventilation. Summary of the invention

[0003] The present invention is based on the inventor's discovery and understanding of the following facts and problems:

[0004] With the promotion and development of large-scale, high-yield and high-efficiency mines, in order to meet the needs of coal mine production, the number of mines with long-distance excavation working faces of more than 2000m and local ventilation distances of more than 2000m is increasing.

[0005] In the related technologies, by optimizing local ventilation management, configuring new advanced high-power ventilation equipment, and implementing wind tube resistance reduction and leakage reduction measures, sufficient air supply and reasonable air volume distribution are ensured in the excavation tunnel, thereby achieving the purpose of ventilation and dust reduction at the head of the excavation tunnel. However, this method achieves ventilation and dust reduction at the head of long-distance excavation tunnels by improving local ventilation management and adding advanced equipment, and does not improve the ventilation method. In addition, this method is suitable for excavation tunnels with stable geological conditions and large tunnel sections, and the investment and maintenance of facilities and equipment in the later excavation projects are relatively large.

[0006] Alternatively, in the related art, large-diameter directional drilling is used to pre-extract gas from the existing tunnel to the tunnel area to be excavated, and the large-diameter directional drilling is used to ventilate the excavation working face during tunnel excavation. Although this method changes the ventilation mode of coal tunnel excavation, floating coal and dust in the excavation tunnel can be extracted through the directional holes, but the long-distance directional drilling of existing tunnels underground has the problems of inconvenience in construction, great technical difficulty and high engineering cost.

[0007] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0008] To this end, an embodiment of the present invention proposes a ventilation method for a long-distance tunnel excavation working face, which plays a role in improving the working environment at the head of the excavation.

[0009] The ventilation method for a long-distance tunnel excavation working face according to an embodiment of the present invention comprises:

[0010] Before the tunnel mining, L-shaped horizontal well drilling operations are carried out at the selected well location;

[0011] Install extraction equipment on the ground and conduct gas pre-extraction operations on the main coal seam through L-shaped horizontal wells;

[0012] Before tunneling, the L-shaped horizontal well used for ground gas extraction before coal seam mining is used as the return air channel for tunneling;

[0013] When the coal seam is mined to the control range of the L-shaped horizontal well, the tunnel excavation direction is kept consistent with the horizontal section of the L-shaped horizontal well;

[0014] During the tunnel excavation process, ventilation equipment is connected to the tunnel excavation face for pressure ventilation. At the same time, ground gas extraction equipment is used to provide auxiliary negative pressure ventilation to the excavation working face through the horizontal section of the L-shaped horizontal well.

[0015] The ventilation method for the long-distance tunnel excavation working face in the embodiment of the present invention makes full use of the L-shaped horizontal well on the ground of the coal mine to achieve multiple uses of one well, and uses it as the return air channel of the excavation tunnel to perform negative pressure assisted ventilation on the excavation working face, thereby overcoming the current situation of dust control, air volume loss, and high ventilation energy consumption in the ventilation process of the long-distance tunnel excavation.

[0016] In some embodiments, a set location is selected for drilling operations based on geological exploration data and mine gas distribution;

[0017] In the drilling operation, vertical drilling is first carried out until the designed depth is reached, and then the horizontal section is drilled using directional drilling tools;

[0018] After the horizontal section is drilled, the well is completed and the ground extraction equipment is connected to the L-shaped horizontal well to start gas pre-extraction.

[0019] In some embodiments, after the gas pre-extraction operation is completed, the horizontal section position of the L-shaped horizontal well is determined to be consistent with the position of the tunnel to be excavated, the casing and wellhead device of the L-shaped horizontal well are inspected and maintained, and the ventilation equipment required for tunnel excavation is prepared.

[0020] In some embodiments, the casing of the L-shaped horizontal well is made of PE or PVC.

[0021] In some embodiments, after the gas pre-extraction operation is completed, the L-shaped horizontal well is expanded so that the aperture of the L-shaped horizontal well reaches a preset value.

[0022] In some embodiments, during the tunnel excavation process, the wind speeds of forced ventilation and negative pressure ventilation are measured, and the total ventilation volume is calculated based on the measured data. The total ventilation volume is compared with a preset ventilation volume standard to adjust the corresponding ventilation equipment.

[0023] In some embodiments, wind speed sensors are installed at the tunnel excavation face and the horizontal section of the L-shaped horizontal well, and the wind speed is measured using the wind speed sensors.

[0024] In some embodiments, when the total ventilation volume is lower than a preset ventilation volume standard, an automatic alarm is triggered.

[0025] In some embodiments, the wind speed sensor is calibrated periodically to eliminate error data of the sensor.

[0026] In some embodiments, a ventilation volume historical data model is established to monitor the fluctuation trend of the ventilation volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the arrangement of an L-shaped horizontal well and a tunneling tunnel according to an embodiment of the present invention.

[0028] Figure 2 It is a schematic AA cross-sectional view of the arrangement of an L-shaped horizontal well and a tunneling tunnel according to an embodiment of the present invention.

[0029] Figure 3 It is a BB cross-sectional schematic diagram of the arrangement of the L-shaped horizontal well and the tunneling tunnel according to an embodiment of the present invention.

[0030] Figure 4 Schematic diagram of ventilation according to an embodiment of the present invention.

[0031] Reference numerals:

[0032] 1-ground gas extraction equipment, 2-L-type horizontal well, 3-main mining coal seam, 4-designed tunnel location, 5-ground, 6-tunnel excavation direction, 7-wind duct, 8-fresh air flow, 9-tunnel return air flow, 10-horizontal well return air flow, 11-tunnel head. DETAILED DESCRIPTION

[0033] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0034] The ventilation method for a long-distance tunnel excavation working face according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0035] like Figures 1 to 4 As shown, the ventilation method for a long-distance tunnel excavation working face according to an embodiment of the present invention includes:

[0036] Before the tunnel is mined, the L-shaped horizontal well 2 is drilled at the selected well location. The extraction equipment is installed on the ground 5, and the gas pre-extraction operation is performed on the main mining coal seam 3 using the ground gas extraction equipment 1 and the L-shaped horizontal well 2. In other words, when the coal seam is not mined, the horizontal section of the L-shaped horizontal well 2 is drilled in the main mining coal seam 3, and is normally used for gas pre-extraction after completion.

[0037] After the gas pre-extraction is completed, the L-shaped horizontal well 2 used for gas extraction when the coal seam is not mined is used as the return air channel for the excavation tunnel.

[0038] When the coal seam is mined to the control range of the L-shaped horizontal well 2, the tunnel excavation direction 6 is kept consistent with the horizontal section of the L-shaped horizontal well 2. That is, the L-shaped horizontal well 2 is used for auxiliary ventilation, and the coal mining and excavation continuation plan needs to be designed in a coordinated manner with the layout of the L-shaped horizontal well 2 on the ground 5, that is, to ensure that the horizontal section position of the L-shaped horizontal well 2 is consistent with the subsequent designed tunnel position 4.

[0039] During the tunnel excavation process, ventilation equipment (e.g., air duct 7 and air compressor connected thereto) is connected to the tunnel excavation face for forced ventilation, and fresh air flow 8 is sent into the tunnel head 11 through the air duct 7, and the tunnel return air flow 9 is opposite to the tunnel excavation direction 6. At the same time, the ground gas extraction equipment 1 is used to perform auxiliary negative pressure ventilation on the excavation working face through the horizontal section of the L-shaped horizontal well 2, and the horizontal well return air flow 10 flows back to the ground 5 through the horizontal section for purification.

[0040] Therefore, the ventilation method for the long-distance tunnel excavation working face of the embodiment of the present invention makes full use of the L-shaped horizontal well 2 on the coal mine surface 5 to achieve multiple uses of one hole, and uses it as the return air channel of the excavation tunnel to perform negative pressure assisted ventilation on the excavation working face, thereby overcoming the current situation of dust control, air volume loss, and high ventilation energy consumption during the ventilation process of long-distance tunnel excavation.

[0041] In some embodiments, the construction operation of the L-shaped horizontal well 2 includes:

[0042] According to the geological exploration data and the distribution of mine gas, select the set location for drilling operations; First, according to the geological exploration data and the distribution of mine gas, select a suitable location for drilling the L-type horizontal well 2. When selecting the location, factors such as the thickness, inclination, gas content of the coal seam and ground 5 conditions should be taken into consideration.

[0043] Carry out ground preparation work at the selected well site, including leveling the well site, setting up the drilling platform, installing the drilling equipment, etc.

[0044] First, vertical drilling is carried out until the designed depth is reached, which is usually a certain distance below the coal seam to ensure smooth penetration. When the predetermined depth is reached, the horizontal section is drilled using directional drilling techniques.

[0045] During the drilling process, in order to keep the well wall stable and prevent hole collapse, it is necessary to inject suitable drilling fluid, and solid proppants or foams may be used to stabilize the well wall.

[0046] After the horizontal section is drilled, the well is completed, including casing, cementing and other steps to ensure the stability and safety of the well wall. After the well is completed, the ground gas extraction equipment 1 is connected to the horizontal well to prepare for gas pre-extraction.

[0047] It should be noted that the ground gas extraction equipment 1 includes extraction pumps, pipelines, valves, flow meters and other necessary monitoring equipment. After all equipment is installed, the system is debugged to ensure that all equipment operates normally and there is no leakage in the pipeline system.

[0048] During the gas pre-extraction process, regularly monitor wellhead pressure, pipeline pressure, extraction flow and other parameters to ensure stable operation of the system. Monitor the dynamic changes of gas in the coal seam and adjust the extraction parameters in time to optimize the extraction effect. Regularly maintain the extraction equipment to ensure the reliability and safety of equipment operation.

[0049] In some embodiments, after the gas pre-extraction operation is completed, the horizontal section position of the L-shaped horizontal well 2 is determined to be consistent with the position of the roadway to be excavated, that is, to ensure that the docking design of the L-shaped horizontal well 2 and the roadway excavation direction 6 is reasonable, and the horizontal section is consistent with the roadway axis. Check and maintain the casing and wellhead device of the L-shaped horizontal well 2 to ensure structural integrity and good air tightness. Prepare ventilation equipment required for roadway excavation, such as air ducts 7, local ventilators, etc.

[0050] It is understandable that when the tunnel is excavated, the L-shaped horizontal well 2 is used as the return air channel. Negative pressure is generated by the ground 5 extraction system to form auxiliary ventilation. The air duct 7 is connected to the tunnel excavation face to perform conventional pressure-in ventilation to provide fresh air flow 8. Using the negative pressure of the L-shaped horizontal well 2, the dirty air in the tunnel is pumped back to the ground 5 using the horizontal well return air flow 10, thereby forming an effective ventilation cycle.

[0051] Furthermore, in order to ensure that the connection design between the L-shaped horizontal well 2 and the tunnel excavation direction 6 is reasonable, it is necessary to conduct detailed geological exploration of the coal seam and its surrounding rock formations before tunnel excavation to obtain accurate geological data. The trend, inclination, thickness and gas distribution of the coal seam are analyzed to provide basic data for the design of the L-shaped horizontal well 2.

[0052] Combined with the mining plan and long-term planning of the mine, the location and excavation direction of the tunnel are determined. According to the production needs and safety standards of the mine, the location of the L-shaped horizontal shaft 2 and the direction of the horizontal section are planned.

[0053] Therefore, according to the geological exploration results and mining plan, a docking scheme is designed for the horizontal section of the L-shaped horizontal well 2 and the tunnel excavation direction 6. It is ensured that the horizontal section of the L-shaped horizontal well 2 can cover the range of tunnel excavation and provide an effective ventilation and gas extraction path.

[0054] In some embodiments, the casing of the L-shaped horizontal well 2 is made of PE or PVC.

[0055] It is understandable that during the tunnel excavation process, coal cutting equipment is used for normal cutting operations. To ensure that the excavation is not affected, the casing of the L-shaped horizontal well 2 is made of PE or PVC.

[0056] During tunneling, geological deformation may occur to a certain extent. PE and PVC casings can better adapt to such deformation and are not as prone to rupture as metal materials. PE and PVC casings are lighter, easier to install and maintain, and will not cause additional burden on tunneling equipment. In addition, these plastic materials do not produce sparks, making them safer to use in mines and reducing the risk of safety accidents.

[0057] In some embodiments, after the gas pre-extraction operation is completed, the L-shaped horizontal well 2 is expanded to make the aperture of the L-shaped horizontal well 2 reach a preset value.

[0058] Among them, according to the principles of fluid mechanics, the ventilation volume is proportional to the ventilation cross-sectional area. Therefore, the increased aperture after hole expansion can directly lead to an increase in ventilation volume. The hole expansion operation needs to ensure the stability of the borehole to avoid the collapse of the hole wall or damage to the casing due to hole expansion, which may affect the ventilation function and safety of the horizontal well.

[0059] Therefore, through the hole expansion operation, the ventilation design of the L-shaped horizontal well 2 can be optimized to better meet the ventilation needs of long-distance tunnel excavation.

[0060] In some embodiments, during the tunnel excavation process, the wind speeds of forced ventilation and negative pressure ventilation are measured, and the total ventilation volume is calculated based on the measured data. The total ventilation volume is compared with a preset ventilation volume standard to adjust the corresponding ventilation equipment.

[0061] Optionally, wind speed sensors are installed at the tunnel excavation face and the horizontal section of the L-shaped horizontal well 2 to measure the wind speed of the forced ventilation and negative pressure ventilation in real time. The forced ventilation volume and the auxiliary negative pressure ventilation volume of the L-shaped horizontal well 2 are calculated using the data collected by the wind speed sensors using special calculation software or algorithms. These calculation results are then summarized to obtain the total ventilation volume of the tunnel excavation face.

[0062] Furthermore, the calculated total ventilation volume is displayed in real time in the monitoring system, so that mine managers can keep track of the ventilation status at any time and make adjustments according to the actual situation. The calculated total ventilation volume is compared with the preset safe ventilation volume standard to ensure that the ventilation needs of mine safety production are met.

[0063] When the monitored ventilation volume is lower than the preset safety standard, the monitoring system automatically activates the alarm system and prompts the operator through sound, light or electronic means. According to the prompt, the operator takes corresponding adjustment measures, such as increasing the wind pressure of the fan, checking the patency of the wind tube 7 and the L-shaped horizontal well 2, to ensure that the ventilation volume meets the needs of safe production.

[0064] Therefore, by measuring and calculating the ventilation volume in real time, it is possible to ensure that sufficient ventilation is always maintained during tunnel excavation, effectively dilute and discharge gas and other harmful gases, and improve ventilation efficiency. By comparing with the preset safe ventilation volume standard, it is ensured that the ventilation system can meet the requirements of safe production at any time, reducing the risk of gas accidents. The activation of the automatic alarm system reduces the need to rely on manual detection and intervention, and improves the automation level of ventilation management.

[0065] In some embodiments, a calibration procedure is used to periodically calibrate the wind speed sensor to eliminate the impact of sensor errors on monitoring data.

[0066] Optionally, a standard wind speed generator is used to generate a stable wind speed signal, the wind speed sensor is exposed to the wind speed signal generated by the standard wind speed generator, and the sensor output value is recorded. The sensor error is calculated based on the sensor output value and the standard wind speed value. Based on the calculated sensor error, the sensor or its parameters are adjusted to reduce the error.

[0067] Therefore, through calibration work, errors caused by long-term use, environmental factors or other reasons of the wind speed sensor can be eliminated or reduced, thereby improving the accuracy of the monitoring data.

[0068] In some embodiments, a ventilation volume historical data model is established to monitor the fluctuation trend of the ventilation volume.

[0069] Specifically, first, the system automatically collects historical data on ventilation volume over a long period of time, including forced ventilation volume and negative pressure ventilation volume in different time periods.

[0070] The collected historical data is then analyzed using statistical methods and data analysis tools to identify ventilation fluctuation patterns and trends. This includes analyzing daily average ventilation, peak ventilation, and periodic changes in ventilation.

[0071] Based on the results of historical data analysis, a mathematical model is constructed to describe the relationship between ventilation volume and time, mine conditions (such as gas outflow, temperature, humidity, etc.), ventilation equipment status, etc. The model can be a linear model, a nonlinear model, or a more complex machine learning model.

[0072] The established mathematical model is used to predict ventilation volume and provide decision support for mine ventilation management, including predicting future ventilation demand, optimizing the operating parameters of ventilation equipment, and identifying potential safety risks in advance.

[0073] It is understandable that by establishing a historical ventilation data model, future ventilation needs can be predicted more accurately, thereby improving the efficiency and response speed of ventilation management. The model can help mine managers better understand the fluctuation pattern of ventilation volume, so as to allocate ventilation resources more reasonably and reduce resource waste. By analyzing the fluctuation trend of ventilation volume, possible safety risks such as insufficient ventilation or excessive ventilation can be identified in advance, so that preventive measures can be taken.

[0074] In summary, the ventilation method for the long-distance tunneling working face of the embodiment of the present invention uses the L-shaped horizontal well 2 on the ground 5 to pre-extract coal seam gas from the unmined area before tunneling. When tunneling, the L-shaped horizontal well 2 on the ground 5 is used for extraction ventilation, which can assist the tunnel head 11 with ventilation, improve the head wind field, play the role of ventilation, dust reduction, and gas extraction, and significantly improve the working environment of the tunneling working face. It should be noted that the horizontal well design and mining connection design that are suitable for this method need to be carried out in a coordinated manner.

[0075] As a result, the L-shaped horizontal well 2 on the ground 5 can be used for multiple purposes, with the functions of "gas pre-extraction and working face ventilation". In the unmined stage of the coal seam, gas pre-extraction is carried out to effectively reduce the gas content of the coal seam to ensure safe production, and auxiliary ventilation is carried out during tunnel excavation.

[0076] Fresh air flow 8 enters the tunnel head 11 through the air duct 7, and part of the dust, floating coal and coal wall gas of the excavation working face are extracted along the drill hole, which can effectively reduce the dust and gas concentration in the excavation head and significantly improve the working environment of the excavation working face. In addition, compared with the improvement method of the related art, the method of the present invention does not increase the workload.

[0077] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0078] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0079] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0080] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0081] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0082] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A ventilation method for a long-distance tunnel excavation working face, characterized in that: include: Before the tunnel mining, L-shaped horizontal well drilling operations are carried out at the selected well location; Install extraction equipment on the ground and conduct gas pre-extraction operations on the main coal seam through L-shaped horizontal wells; Before tunneling, the L-shaped horizontal well used for ground gas extraction before coal seam mining is used as the return air channel for tunneling; When the coal seam is mined to the control range of the L-shaped horizontal well, the tunnel excavation direction is kept consistent with the horizontal section of the L-shaped horizontal well; During the tunnel excavation process, ventilation equipment is connected to the tunnel excavation face for pressure ventilation. At the same time, ground gas extraction equipment is used to provide auxiliary negative pressure ventilation to the excavation working face through the horizontal section of the L-shaped horizontal well.

2. The long-distance tunnel excavation working face ventilation method according to claim 1 is characterized in that: According to geological exploration data and mine gas distribution, select the set location for drilling operations; In the drilling operation, vertical drilling is first carried out until the designed depth is reached, and then the horizontal section is drilled using directional drilling tools; After the horizontal section is drilled, the well is completed and the ground extraction equipment is connected to the L-shaped horizontal well to start gas pre-extraction.

3. The long-distance tunnel excavation working face ventilation method according to claim 2 is characterized in that: After the gas pre-extraction operation is completed, make sure that the horizontal section of the L-shaped horizontal well is consistent with the position of the tunnel to be excavated, check and maintain the casing and wellhead device of the L-shaped horizontal well, and prepare the ventilation equipment required for tunnel excavation.

4. The long-distance tunnel excavation working face ventilation method according to claim 3 is characterized in that: The casing of L-type horizontal wells is made of PE or PVC.

5. The long-distance tunnel excavation working face ventilation method according to any one of claims 1 to 4, characterized in that: After the gas pre-extraction operation is completed, the L-type horizontal well is expanded to make the aperture of the L-type horizontal well reach the preset value.

6. The long-distance tunnel excavation working face ventilation method according to claim 5, characterized in that: During the tunnel excavation process, the wind speeds of forced ventilation and negative pressure ventilation are measured, and the total ventilation volume is calculated based on the measured data. The total ventilation volume is compared with the preset ventilation volume standard to adjust the corresponding ventilation equipment.

7. The long-distance tunnel excavation working face ventilation method according to claim 6 is characterized in that: Wind speed sensors are installed on the tunnel excavation face and the horizontal section of the L-shaped horizontal well, and the wind speed is measured using the wind speed sensors.

8. The ventilation method for long-distance tunnel excavation working face according to claim 6, characterized in that: When the total ventilation volume is lower than the preset ventilation volume standard, an automatic alarm will be given.

9. The ventilation method for long-distance tunnel excavation working face according to claim 7, characterized in that: The wind speed sensor should be calibrated regularly to eliminate the error data of the sensor.

10. The ventilation method for long-distance tunnel excavation working face according to claim 9, characterized in that: Establish a ventilation volume historical data model to monitor the fluctuation trend of ventilation volume.

Images