Extra-long drill hole pressure relief device for driving working face

Abstract

The invention relates to the technical field of gas extraction drilling, and discloses a driving working face super-long drilling pressure relief device which comprises a plurality of screen pipes, the screen pipes are placed in a drilling hole for supporting work, a plurality of through holes are formed in the outer walls of the screen pipes, rectangular grooves are formed in the two ends of each screen pipe, and pressure relief pipes are inserted into the screen pipes. Through holes are also formed in the outer wall of the pressure relief pipe, movable grooves are formed in the two ends of the pressure relief pipe, the movable grooves are formed below the rectangular grooves, the buffering sleeve is used for sealing the connecting positions of the multiple screen pipes, and a cavity is formed in the buffering sleeve. The technical means that the screen pipes are matched with the pressure relief pipe is adopted, media such as high-pressure gas and water in a drill hole are preliminarily gathered through the screen pipe through holes and then directionally guided out through the pressure relief pipe, the flow guide path is clear, the gathering efficiency is high, the buffering sleeves at the connecting positions of the adjacent screen pipes achieve splicing gap sealing, medium leakage is avoided, the pressure relief and drainage effects are further improved, and the service life of the drill hole is prolonged. And rock burst and gas outburst risks of the driving face are effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of gas extraction drilling technology, specifically to a pressure relief device for ultra-long boreholes in tunneling faces. Background Technology

[0002] my country is a country rich in coal resources. As my country's coal mines are entering deeper mining at an average annual growth rate of about 25m, high-stress and high-gas mines are increasing. Deep mines have greater deformation energy accumulated in the rock strata, and the roof also accumulates a large amount of elastic energy during mining. Fault areas are prone to forming high-stress zones, which have the conditions for dynamic pressure phenomena. Furthermore, the presence of high gas directly affects the physical and deformation properties of coal and rock masses, and gas pressure acts on the coal and rock masses in the form of volume force, which promotes the occurrence of rockbursts. Moreover, rockbursts are accompanied by a large amount of gas outburst, which can easily cause other disasters. In order to reduce the possibility of disasters and improve the safety of mine mining, it is currently necessary to construct face and gas drainage holes when controlling rockbursts and gas disasters during the tunneling and mining of high-gas and rockburst mines.

[0003] During the work process, it is necessary to first verify the geological data (including rock stratum dip angle, gas content, and stress distribution), check the integrity of the directional drilling rig, drill rod, and measuring instruments, mark the borehole opening position, adopt measurement while drilling technology to monitor the borehole trajectory in real time, check the deviation every 5m, and correct the deviation in time when it exceeds the tolerance. After drilling to the design depth, clean the rock powder in the hole, and put in the screen pipe to protect the hole wall to avoid the hole collapse and blockage of the pressure relief channel. After the hole is completed, stress sensors and gas monitoring points are immediately set up and continuously monitored for 72 hours. Excavation can only proceed after confirming that the pressure relief meets the standards (stress reduction ≥30% and gas concentration stable below the safe value).

[0004] In soft coal seams, ordinary steel casing is too rigid and cannot adapt to coal seam deformation. It is easily squeezed, bent and broken, which in turn scratches the borehole wall and aggravates the borehole collapse. In addition, a large number of screen pipes are required in long boreholes. The sealing effect of the screen pipe joints is difficult to verify. After grouting, it can only be preliminarily judged by the pressure curve. It is impossible to directly confirm whether there is grout leakage or voids, leaving long-term safety hazards. Summary of the Invention

[0005] This invention provides an ultra-long borehole pressure relief device for tunneling faces to solve the problems mentioned in the background art, such as the excessive rigidity of existing ordinary steel casings, which are difficult to adapt to coal seam deformation and are easily squeezed, bent, or broken.

[0006] This invention provides a pressure relief device for an ultra-long borehole in a tunneling face, including multiple screen pipes placed inside the borehole for support. Rectangular grooves are provided at both ends of the screen pipes. The pressure relief pipe is inserted into the screen pipe. Both the screen pipe and the outer wall of the pressure relief pipe have through holes. Both ends of the pressure relief pipe have movable grooves, which are located below the rectangular groove. The buffer sleeve is used to seal the connection of multiple screen tubes. The buffer sleeve has a cavity inside, and multiple straightening chambers are arranged around the outer wall of the buffer sleeve. The straightening chambers are connected to the inside of the buffer sleeve. A fiber optic sensor is fixedly installed on the top wall of the inner side of the buffer sleeve to monitor key parameters such as the deformation of the surrounding rock, the temperature of the medium, and the flow rate in real time.

[0007] Preferably, the through holes are distributed in a spiral shape, and the inner diameter of the through holes is set to 8-10 mm.

[0008] Preferably, the screen pipe is a double-layer composite pipe, which is composed of an outer PE plastic layer and an inner steel layer.

[0009] Preferably, the inner diameter of the screen tube is 20-30 mm smaller than that of the borehole.

[0010] Preferably, the buffer sleeve is made of a high-temperature and high-pressure resistant material, and the straightening bag is made of an elastic and deformable material.

[0011] Preferably, the buffer sleeve is configured as an openable cylindrical structure, and multiple bolts can be installed at the opening of the buffer sleeve for connection.

[0012] Preferably, the side wall of the buffer sleeve is fixedly connected to an air inlet pipe and an air outlet pipe, and both the air inlet pipe and the air outlet pipe are equipped with a one-way valve.

[0013] Preferably, the radius of the fiber optic sensor is smaller than the distance between the inner diameter of the rectangular groove and the movable groove.

[0014] Preferably, multiple buffer rings are fixedly connected to the outer wall of the pressure relief pipe, and the outer wall of the buffer rings abuts against the inner wall of the screen pipe.

[0015] Preferably, the buffer ring is made of a water-swellable material.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention employs a combination of screen pipes and pressure relief pipes. High-pressure gas, water, and other media in the borehole are initially collected through the screen pipe's through-holes and then directed out through the pressure relief pipe. The flow path is clear and the collection efficiency is high. The buffer sleeve at the connection of adjacent screen pipes seals the joint gaps, preventing media leakage and further improving the pressure relief and drainage effects. This effectively reduces the risk of rock pressure and gas outbursts at the tunneling face and overcomes the shortcomings of existing ultra-long borehole pressure relief devices, such as easy leakage, susceptibility to damage from surrounding rock, low pressure relief efficiency, and lack of real-time monitoring. Thus, it achieves the technical effects of high-efficiency pressure relief, stable and durable structure, adaptability to complex geological conditions, and strong safety and controllability.

[0017] This invention employs a combination of spiral through-holes, double-layer composite screen pipes, and water-expanding buffer rings. By utilizing the working principles of uniform flow convergence and anti-clogging spiral through-holes, reinforced support and anti-extrusion of the double-layer composite structure, and elastic protection and self-sealing of the expansion buffer rings, it overcomes the shortcomings of existing ultra-long borehole pressure relief devices, such as uneven flow convergence leading to clogging, weak resistance of pipe materials to surrounding rock extrusion, and easy leakage of media. As a result, it achieves the technical effects of high pressure relief efficiency, strong structural stability, adaptability to complex water-rich geological conditions, and long service life.

[0018] This invention employs a combination of a high-temperature, high-pressure resistant, openable and closable buffer sleeve and a controllable inflation and deflation elastic support bag. It utilizes the principles of convenient installation via the openable and closable structure, directional inflation and deflation for pressure regulation of the support bag, and anti-collision design of the fiber optic sensor to ensure stable monitoring. This overcomes the shortcomings of existing technologies, such as cumbersome buffer sleeve installation, susceptibility to breakage due to surrounding rock pressure, and easy damage and failure of the fiber optic sensor. Consequently, it achieves the technical effects of convenient installation and maintenance, strong adaptability to working conditions, accurate monitoring data, and a stable and durable overall structure. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the overall structure of the screen tube of the present invention; Figure 3 This is a schematic diagram of the overall structure of the screen tube and pressure relief tube of the present invention; Figure 4 This is a schematic diagram of the overall cross-sectional structure of the screen tube and pressure relief tube of the present invention; Figure 5 This is a schematic diagram of the overall structure of the buffer sleeve of the present invention; Figure 6 This is a schematic diagram of the overall structure of the back of the buffer sleeve of the present invention; Figure 7 This is a schematic diagram of the overall internal structure of the buffer sleeve of the present invention.

[0020] In the diagram: 100, sieve tube; 101, through hole; 102, rectangular groove; 200. Pressure relief pipe; 201. Buffer ring; 202. Movable groove; 300. Buffer sleeve; 301. Correcting bag; 302. Air inlet pipe; 303. Air outlet pipe; 400. Fiber optic sensor. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention discloses a pressure relief device for ultra-long boreholes in tunneling faces, such as... Figure 1-7 As shown, it includes a screen tube 100, and multiple screen tubes 100 are provided. They are placed in the borehole for support. Rectangular grooves 102 are provided at both ends of the screen tube 100. It should be noted that the pressure relief pipe 200 is inserted into the screen pipe 100. Both the screen pipe 100 and the outer wall of the pressure relief pipe 200 are provided with through holes 101. Both ends of the pressure relief pipe 200 are provided with movable grooves 202, which are located below the rectangular groove 102. It should be noted that the buffer sleeve 300 is used to seal the connection of multiple screen tubes 100. The buffer sleeve 300 has a cavity inside, and multiple straightening chambers 301 are arranged around the outer wall of the buffer sleeve 300. The straightening chambers 301 are connected to the inside of the buffer sleeve 300. A fiber optic sensor 400 is fixedly installed on the top wall inside the buffer sleeve 300 to monitor key parameters such as deformation of the surrounding rock, temperature of the medium, and flow rate in real time.

[0023] Furthermore, the built-in cavity of the buffer sleeve 300 is connected to the outer wall straightening bladder 301. After being inflated or filled with liquid, the straightening bladder 301 can fit tightly against the borehole wall, serving both centering and buffering functions, thus significantly improving the service life of the device under complex geological conditions.

[0024] Furthermore, the buffer sleeve 300 integrates a fiber optic sensor 400, which can monitor key parameters such as the deformation of the surrounding rock in the borehole (through pressure changes in the centralizing chamber 301), medium temperature and flow rate in real time. When the parameters are abnormal, it can issue an early warning in time, realize dynamic monitoring and precise control of the depressurization process, and avoid safety accidents caused by parameter loss.

[0025] The working principle of the above technical solution is as follows: During on-site construction, multiple screen pipes 100 are sequentially spliced ​​and placed into a pre-drilled extra-long borehole. The structure of the screen pipes 100 themselves supports the borehole wall, preventing problems such as borehole collapse and diameter reduction, thus ensuring the stability and conductivity of the borehole. High-pressure gas, water, and other pressure-relieving media inside the borehole can enter the interior of the screen pipes 100 through multiple through holes 101 opened on the outer wall of the screen pipes 100. At the same time, a pressure relief pipe 200 is inserted into the screen pipes 100, and the pressure-relieving media will... The gas is further collected in the pressure relief pipe 200 and guided to the ground or a designated collection device through the pressure relief pipe 200. This achieves gas depressurization and water drainage at the tunneling face, reducing the risk of rock pressure and gas outburst at the working face. The rectangular grooves 102 at both ends of the screen pipe 100 and the movable grooves 202 at both ends of the pressure relief pipe 200 cooperate with each other, ensuring the alignment accuracy of the screen pipe 100 during splicing and providing a margin for the installation and adjustment of the pressure relief pipe 200 within the screen pipe 100, thus avoiding pipe jamming caused by borehole offset. During use, a buffer sleeve 300 is fitted at the connection between two adjacent screen tubes 100. The cavity structure of the buffer sleeve 300 can seal the joint of the screen tubes 100, preventing the pressure relief medium from leaking from the gap and improving the pressure relief efficiency. The centralizing bladder 301 surrounding the outer wall of the buffer sleeve 300 is connected to the internal cavity of the buffer sleeve 300. After the buffer sleeve 300 is installed in place, the centralizing bladder 301 can be expanded by injecting a medium (such as high-pressure gas or liquid) into the cavity. The expanded centralizing bladder 301 fits tightly against the borehole wall, which on the one hand realizes the overall centering and straightening of the screen tube 100 in the borehole, avoiding the blockage of the through hole 101 caused by the screen tube 100 partially sticking to the wall, and on the other hand, the elasticity of the centralizing bladder 301 buffers the squeezing damage to the screen tube 100 caused by the deformation of the surrounding rock in the borehole, extends the service life of the device, and mitigates the impact of the deformation. The fiber optic sensor 400, fixedly installed on the inner top wall of the punch sleeve 300, can monitor key parameters inside the borehole in real time: First, it monitors the pressure changes of the centralizing chamber 301 through the strain sensing function of the fiber optic cable, indirectly reflecting the deformation trend of the surrounding rock. Second, it can monitor parameters such as the temperature and flow rate of the pressure relief medium. When the parameters are abnormal (such as sudden pressure rise or fall, or abnormal temperature rise), it promptly sends an early warning signal to the ground control system, which facilitates the staff to adjust the pressure relief plan in time and ensures the safe production of the tunneling face. The device achieves efficient pressure relief through the double-layer flow guiding structure of the screen pipe 100 and the pressure relief pipe 200. It ensures the stability of the device by means of the sealing and centralizing structure of the buffer sleeve 300 and the centralizing chamber 301. It achieves intelligent monitoring by means of the fiber optic sensor 400, forming an integrated ultra-long borehole pressure relief system that combines support, pressure relief, sealing and monitoring.

[0026] This invention employs a combination of screen pipe 100 and pressure relief pipe 200. High-pressure gas, water, and other media in the borehole are initially collected through the through hole 101 of screen pipe 100, and then directionally discharged through pressure relief pipe 200. The flow path is clear and the collection efficiency is high. The buffer sleeve 300 at the connection of adjacent screen pipes 100 seals the splicing gap, preventing media leakage and further improving the pressure relief and drainage effect. This effectively reduces the risk of rock pressure and gas outburst at the tunneling face, and overcomes the shortcomings of existing ultra-long borehole pressure relief devices, such as easy leakage, susceptibility to damage from surrounding rock, low pressure relief efficiency, and lack of real-time monitoring. Thus, it achieves the technical effects of high-efficiency pressure relief, stable and durable structure, adaptability to complex geological conditions, and strong safety and controllability.

[0027] In one specific embodiment: the through holes 101 are distributed in a spiral shape, and the inner diameter of the through holes 101 is set to 8-10 mm.

[0028] It should be noted that the screen pipe 100 is a double-layer composite pipe, which is composed of an outer PE plastic layer and an inner steel layer.

[0029] It should be noted that the inner diameter of the screen tube 100 is 20-30 mm smaller than that of the borehole.

[0030] In addition, multiple buffer rings 201 are fixedly connected to the outer wall of the pressure relief pipe 200, and the outer wall of the buffer rings 201 abuts against the inner wall of the screen pipe 100.

[0031] Specifically, the buffer ring 201 is made of a water-swellable material.

[0032] The working principle of the above technical solution is as follows: During the use of this invention, the through holes 101 on the outer wall of the screen tube 100 adopt a spiral distribution design with an inner diameter controlled at 8-10mm. Compared with the traditional straight-line arrangement of through holes 101, the spiral distribution allows high-pressure gas, water and other pressure relief media at different depths and directions in the borehole to enter the screen tube 100 more evenly and comprehensively, avoiding local convergence blind spots. The inner diameter of 8-10mm can effectively block coal and rock debris in the borehole from entering the screen tube 100 while ensuring the rapid passage of the media, preventing the through holes 101 and pressure relief pipe 200 from becoming blocked, and ensuring that the pressure relief channel is unobstructed for a long time. During use, the screen pipe 100 adopts a double-layer composite structure of an outer PE plastic layer and an inner steel layer. The inner steel layer provides high-strength structural support, which can resist the compression deformation of the surrounding rock under complex geological conditions and prevent the screen pipe 100 from collapsing. The outer PE plastic layer has corrosion-resistant and wear-resistant properties, which can prevent the corrosive media in the borehole from eroding the steel layer and extend the service life of the screen pipe 100. At the same time, the inner diameter of the screen pipe 100 is 20-30mm larger than the borehole, leaving sufficient installation and deformation margin. This facilitates the insertion and adjustment of the pressure relief pipe 200 and can adapt to the borehole diameter changes caused by the deformation of the surrounding rock, reducing the risk of pipe jamming. During use, multiple buffer rings 201 fixedly connected to the outer wall of the pressure relief pipe 200 are made of water-swellable material, and their outer walls abut against the inner wall of the screen pipe 100. On the one hand, the buffer rings 201 can form an elastic support between the pressure relief pipe 200 and the screen pipe 100, buffering the collision and friction between the two and reducing pipe wear. On the other hand, when groundwater seeps into the borehole, the buffer rings 201 automatically expand upon contact with water, further filling the gap between the pressure relief pipe 200 and the screen pipe 100, achieving self-sealing of the gap, preventing the pressure relief medium from leaking from the gap. At the same time, the expanded buffer rings 201 can enhance the central stability of the pressure relief pipe 200 within the screen pipe 100, avoiding poor flow due to the displacement of the pressure relief pipe 200. During use, the structural design of this embodiment works in conjunction with the basic scheme's buffer sleeve 300, the centralizing bladder 301 sealing and centralizing structure, and the fiber optic sensor 400 monitoring structure: the medium flowing through the spiral through-hole 101 is directionally discharged through the pressure relief pipe 200, the double-layer composite screen pipe 100 and the expansion buffer ring 201 ensure the stability of the device structure, the centralizing bladder 301 of the buffer sleeve 300 enables the screen pipe 100 to be centered as a whole, and the fiber optic sensor 400 monitors the surrounding rock deformation and medium parameters in real time.

[0033] This invention employs a combination of a spiral through-hole 101, a double-layer composite screen pipe 100, and a water-swellable buffer ring 201. By utilizing the working principles of the spiral through-hole 101 for uniform flow and anti-clogging, the double-layer composite structure for enhanced support and anti-extrusion, and the expansion buffer ring 201 for elastic protection and self-sealing, it overcomes the shortcomings of existing ultra-long borehole pressure relief devices, such as uneven flow and easy clogging, weak resistance of pipe materials to surrounding rock extrusion, and easy leakage of media. As a result, it achieves the technical effects of high pressure relief efficiency, strong structural stability, adaptability to complex water-rich geological conditions, and long service life.

[0034] In one specific embodiment: the buffer sleeve 300 is made of a high temperature and high pressure resistant material, and the straightening bag 301 is made of an elastic and deformable material.

[0035] It should be noted that the buffer sleeve 300 is designed as an openable cylindrical structure, and multiple bolts can be installed at the opening of the buffer sleeve 300 for connection.

[0036] It should be noted that the side wall of the buffer sleeve 300 is fixedly connected to an air inlet pipe 302 and an air outlet pipe 303, and both the air inlet pipe 302 and the air outlet pipe 303 are equipped with one-way valves.

[0037] In addition, the radius of the fiber optic sensor 400 is smaller than the distance between the inner diameters of the rectangular slot 102 and the movable slot 202.

[0038] The working principle of the above technical solution is as follows: During use, the buffer sleeve 300 is made of high temperature and high pressure resistant material, which can adapt to the harsh working conditions of high temperature and high gas pressure in the borehole of the tunneling face, avoid deformation and damage of the buffer sleeve 300 due to excessive medium temperature and pressure, and ensure stable sealing performance at the connection. At the same time, the buffer sleeve 300 is designed as an openable cylindrical structure, and the opening is fastened by multiple bolts. Compared with the integral buffer sleeve 300, it can be directly wrapped and installed after the screen pipe 100 is spliced, without the need to pre-fit the buffer sleeve 300 into the screen pipe 100 before splicing the screen pipe 100, which greatly simplifies the on-site installation process. The bolt connection method also facilitates later disassembly and maintenance, reducing the difficulty of device maintenance. During use, the straightening bag 301 is made of elastic and deformable material. One-way valves are installed in the air inlet pipe 302 and air outlet pipe 303 on the side wall of the buffer sleeve 300 to realize the directional inflation and deflation of the straightening bag 301: when high-pressure gas is injected into the cavity of the buffer sleeve 300 and the straightening bag 301 through the air inlet pipe 302, the one-way valve prevents the gas from flowing back. The straightening bag 301 gradually expands and fits tightly against the borehole wall, realizing the centering and straightening of the screen pipe 100 and the sealing of gaps. When the deformation of the surrounding rock of the borehole causes the pressure on the borehole wall to be too high, the gas can be released appropriately through the air outlet pipe 303 to adjust the expansion degree of the straightening bag 301, avoid the straightening bag 301 from breaking due to excessive compression, and improve the adaptability of the device to complex surrounding rock deformation. During use, the radius of the fiber optic sensor 400 is smaller than the distance between the inner diameters of the rectangular groove 102 and the movable groove 202. This size design ensures that the fiber optic sensor 400 will not collide or be squeezed with the rectangular groove 102 of the screen pipe 100 or the movable groove 202 of the pressure relief pipe 200 when the pipe is slightly displaced due to the installation, adjustment, or deformation of the surrounding rock. This avoids damage to the sensor due to mechanical contact. At the same time, the fiber optic sensor 400 is fixed to the inner top wall of the buffer sleeve 300, which can stably monitor the pressure of the straightening bag 301 and the parameters of the medium inside the borehole, ensuring the accuracy and continuity of the monitoring data. During use, the optimized structure of the buffer sleeve 300 and the straightening bag 301, together with the spiral through hole 101 of the screen tube 100, the double-layer composite material, and the water-swellable buffer ring 201 of the pressure relief pipe 200, work together to ensure the reliability of the high temperature and high pressure buffer sleeve 300, enhance the stability of the device with the controllable expansion of the straightening bag 301, and achieve accurate monitoring with the anti-collision fiber optic sensor 400. Ultimately, this improves the depressurization efficiency and safety performance of the entire device under high temperature and high pressure and severe surrounding rock deformation conditions.

[0039] This invention employs a combination of a high-temperature and high-pressure resistant openable and closable buffer sleeve 300 and a controllable inflation and deflation elastic support bag 301. It utilizes the convenient installation of the openable and closable structure, the directional inflation and deflation for pressure regulation of the support bag 301, and the anti-collision design of the fiber optic sensor 400 to ensure stable monitoring. This overcomes the shortcomings of existing technologies, such as the cumbersome installation of the buffer sleeve 300, the susceptibility of the support bag 301 to cracking due to surrounding rock pressure, and the easy damage and failure of the fiber optic sensor 400. Thus, it achieves the technical effects of convenient installation and maintenance, strong adaptability to working conditions, accurate monitoring data, and a stable and durable overall structure.

[0040] The contents not described in detail in this description are existing technologies known to those skilled in the art. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pressure relief device for ultra-long boreholes in a tunneling face, characterized in that, include Screen tube (100), multiple screen tubes (100) are provided and placed in the borehole for support. Rectangular grooves (102) are provided at both ends of the screen tube (100). A pressure relief pipe (200) is inserted into a screen pipe (100). Both the screen pipe (100) and the outer wall of the pressure relief pipe (200) are provided with through holes (101). Both ends of the pressure relief pipe (200) are provided with movable grooves (202). The movable grooves (202) are located below the rectangular groove (102). A buffer sleeve (300) is used to seal the connection of multiple screen tubes (100). The buffer sleeve (300) has a cavity inside. Multiple straightening bags (301) are arranged around the outer wall of the buffer sleeve (300). The straightening bags (301) are connected to the inside of the buffer sleeve (300). A fiber optic sensor (400) is fixedly installed on the top wall of the inner wall of the buffer sleeve (300) for real-time monitoring of key parameters such as deformation of the surrounding rock, temperature of the medium, and flow rate in the borehole.

2. The pressure relief device for ultra-long boreholes in a tunneling face according to claim 1, characterized in that, The through holes (101) are spirally distributed, and the inner diameter of the through holes (101) is set to 8-10 mm.

3. The pressure relief device for ultra-long boreholes in a tunneling face according to claim 1, characterized in that, The screen pipe (100) is configured as a double-layer composite pipe, which is composed of an outer PE plastic layer and an inner steel layer.

4. The pressure relief device for ultra-long boreholes in a tunneling face according to claim 1, characterized in that, The screen tube (100) has an inner diameter that is 20-30 mm smaller than the borehole.

5. A pressure relief device for ultra-long boreholes in a tunneling face according to claim 1, characterized in that, The buffer sleeve (300) is made of a high temperature and high pressure resistant material, and the support bag (301) is made of an elastic and deformable material.

6. A pressure relief device for ultra-long boreholes in a tunneling face according to claim 1, characterized in that, The buffer sleeve (300) is configured as an openable cylindrical structure, and multiple bolts can be provided at the opening of the buffer sleeve (300) for connection.

7. A pressure relief device for ultra-long boreholes in a tunneling face according to claim 1, characterized in that, The buffer sleeve (300) is fixedly connected to an air inlet pipe (302) and an air outlet pipe (303) on its side wall, and a one-way valve is provided in both the air inlet pipe (302) and the air outlet pipe (303).

8. A pressure relief device for ultra-long boreholes in a tunneling face according to claim 1, characterized in that, The radius of the fiber optic sensor (400) is smaller than the distance between the inner diameters of the rectangular groove (102) and the movable groove (202).

9. A pressure relief device for ultra-long boreholes in a tunneling face according to claim 1, characterized in that, The outer wall of the pressure relief pipe (200) is fixedly connected with multiple buffer rings (201), and the outer wall of the buffer rings (201) abuts against the inner wall of the screen pipe (100).

10. A pressure relief device for ultra-long boreholes in a tunneling face according to claim 9, characterized in that, The buffer ring (201) is made of a water-swellable material.

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