Anti-sloughing flexible supporting device and method for gas extraction drill hole

Abstract

The invention discloses a hole collapse prevention flexible supporting device and method for gas extraction drilling, belongs to the technical field of coal mine gas control and drilling supporting, and solves the core problems that an existing gas extraction drilling hole is prone to hole collapse, the supporting technology cannot give consideration to the supporting stability and the gas extraction through-flow property, and the deep hole precise supporting difficulty is large. The device comprises a deep hole grouting drill rod, and a flexible grating grouting supporting bag and a grouting material bag which are in pre-butt joint are arranged in the drill rod; the supporting bag is of a double-cavity integrated structure with a breathable grid, the grouting material bag is of a three-cavity diaphragm pre-packaging structure, and the drill rod is integrated with an automatic control pushing and grouting power unit. According to the method, segmented fixed-point supporting from deep to shallow is adopted, and automatic closed-loop operation of supporting component pushing, mixed grouting and fixed-pressure disconnection is achieved. The method can effectively restrain the hole collapse of the drill hole, gives consideration to the supporting effect and the gas extraction efficiency, adapts to the deep complex geological working conditions, and improves the safety and the operation efficiency of mine gas control.

Description

Technical Field

[0001] This invention belongs to the field of coal mine gas control and borehole support technology, specifically relating to a flexible support device for preventing collapse of gas drainage boreholes, and also to a flexible support method for preventing collapse of gas drainage boreholes. Background Technology

[0002] Mine gas drainage is a core technical means for coal mine gas disaster management and is crucial for ensuring mine safety and realizing the utilization of gas resources. Deep coal seams generally exhibit characteristics of high ground stress, strong mining disturbance, and low permeability. To ensure gas drainage effectiveness, large-diameter gas drainage boreholes and directional long boreholes have become the mainstream technical solutions for deep coal seam gas management. The structural integrity and long-term stability of the borehole wall are the core factors determining gas drainage efficiency, drainage service life, and management costs. During gas drainage operations, due to the poor stability of the coal and rock strata themselves, complex geological structures, and the superposition of ground stress and mining disturbance, gas drainage boreholes are prone to borehole wall deformation and collapse. Especially as the borehole diameter increases, the risk of collapse in the weak coal and rock strata within the borehole is further aggravated. Collapse directly causes blockage of the gas drainage channel and reduction of the effective drainage cross section, resulting in gas drainage effects that fail to meet design requirements. In severe cases, it can even lead to borehole abandonment, significantly increasing gas management costs and posing a major hidden danger to mine safety production.

[0003] Currently, the mainstream approach to controlling borehole collapse in gas drainage is rigid casing support technology. This involves placing rigid components such as metal casings or rigid PVC casings inside the borehole to support the borehole wall. While this approach can suppress borehole wall collapse to some extent, it has unavoidable technical drawbacks: the rigid casing is in hard contact with the surrounding coal and rock, making it unable to adapt to the creep deformation of deep coal and rock and the displacement of the surrounding rock under mining disturbances. It is prone to compression deformation and failure under ground stress, making it impossible to achieve long-term stable support. At the same time, the rigid casing will block the borehole cross-section and the gas seepage channel in the coal wall over a large area, significantly reducing the effective cross-section and extraction efficiency of gas drainage, making it impossible to balance support effectiveness and drainage requirements.

[0004] To address the flowability issues of rigid supports, the industry has gradually adopted bag grouting support technology. This involves placing bags into the borehole and injecting solidified grout, causing the bags to expand and adhere to the borehole wall to form a support. However, existing bag support solutions still face several technical bottlenecks: most existing bags are single-cavity closed structures, which still cannot achieve free gas flow and have not fundamentally resolved the industry contradiction of the incompatibility between support effectiveness and gas flowability; at the same time, existing bag grouting is prone to problems such as insufficient grout injection leading to support failure or excessive grout injection blocking the borehole.

[0005] In summary, existing gas drainage borehole anti-collapse support technologies cannot simultaneously ensure support effectiveness, gas flowability, and operational safety. They are insufficient to meet the engineering requirements for long-term stable support of gas drainage boreholes under deep and complex geological conditions, severely restricting the improvement of mine gas control efficiency and safety production levels. Summary of the Invention

[0006] The primary objective of this invention is to provide a flexible support device for preventing collapse of gas drainage boreholes, which solves the technical problems of easy collapse of gas drainage boreholes and the inability of existing support technologies to simultaneously ensure borehole support stability and gas drainage flowability.

[0007] The second objective of this invention is to provide a flexible support method for preventing collapse of gas drainage boreholes, which solves the technical problem that precise, efficient, segmented, and continuous flexible support cannot be achieved in the deep, easily collapsed areas of gas drainage boreholes.

[0008] The first technical solution adopted in this invention is a flexible support device for preventing collapse of gas extraction boreholes, including a deep hole grouting drill rod. The deep hole grouting drill rod has a flexible grid reinforcement support bag and a grouting material package inside. The inlet of the flexible grid reinforcement support bag and the outlet of the grouting material package are detachably connected. The deep hole grouting drill rod is used to transport the flexible grid reinforcement support bag and the grouting material package to the target support position of the borehole and complete the grouting support operation.

[0009] The first technical solution of this invention is further characterized by:

[0010] The flexible grid injection support bag is a flame-retardant and antistatic polymer elastic material used in underground coal mines. The main body of the flexible grid injection support bag consists of a bottom layer, a middle layer and a top layer stacked in sequence. The bottom layer and the middle layer enclose the first cavity, and the middle layer and the top layer enclose the second cavity. The bottom layer, the middle layer and the top layer are made of the same material and are integrally formed by a one-time molding process.

[0011] The body of the flexible grid injection support bag is a grid structure. The flexible grid injection support bag has several permeable grids that allow coal seam gas to pass through. The first end of the flexible grid injection support bag has an inlet that communicates with the first cavity. The first cavity is used to inject solidifiable grouting material to expand and support the hole wall. The second cavity is filled with heat insulation and shock absorption material.

[0012] A quick-connect device is fixedly installed at the inlet of the flexible grid grouting support bag, and a one-way valve is connected in series at the rear end of the quick-connect device; the one-way valve is directed from the grouting material bag to the inside of the first cavity, and is used to prevent the grout from flowing back during the grouting process.

[0013] The grouting material package is an integrated liquid packaging system. The interior of the grouting material package is divided into three independent chambers: a first chamber, a second chamber, and a third chamber, by easily ruptured and sealed diaphragms. The first chamber and the second chamber are separated by a first easily ruptured and sealed diaphragm, and the second chamber and the third chamber are separated by a second easily ruptured and sealed diaphragm. The first chamber stores a curing time regulating catalyst, the second chamber stores liquid resin, and the third chamber is a mixing chamber connected to the outlet.

[0014] The outlet of the grouting material package is fixedly equipped with an outlet quick connector, which is adapted to and sealed with the quick connector of the flexible grid grouting support bag; the outlet of the grouting material package is also equipped with a burst valve, the burst pressure of which is matched with the rated filling pressure of the flexible grid grouting support bag.

[0015] The grouting material package has a cylindrical packaging structure. At the bottom of the end of the grouting material package opposite to the outlet, there is a movable bottom plug that can move axially. The movable bottom plug is used to push the material inside the grouting material package toward the outlet when subjected to axial compression.

[0016] The deep hole grouting drill rod integrates a flexible grid grouting support bag storage unit, a grouting material package storage unit, a microprocessor, a communication unit, a power push unit, and a power supply unit inside the rod body; The power push unit includes a central rotary rod and a grouting material pack extrusion disc arranged coaxially along the axis of the deep hole grouting drill rod; the rear end of the central rotary rod is connected to the drive module of the power push unit, and the front end of the central rotary rod faces the discharge port of the deep hole grouting drill rod. The flexible grid grouting support bag storage unit is used to pre-load the flexible grid grouting support bag to be deployed, and the grouting material bag storage unit is used to pre-load the grouting material bag after docking. The grouting material bag storage unit and the central rotary rod are connected through a transmission structure and move axially along the deep hole grouting drill rod. The central rotary rod is coaxially inserted into the hollow structure in the middle of the grouting material bag storage unit and the grouting material bag. The grouting material bag extrusion disc is fitted onto the rod body of the central rotary rod through an internal thread structure. It is located at the rear end of the grouting material bag storage unit and is axially aligned with the movable bottom plug of the grouting material bag. The communication unit is used to receive external control signals and transmit them to the microprocessor. After processing the signals, the microprocessor sends execution instructions to the power push unit. The power supply unit supplies power to the aforementioned microprocessor, communication unit, and power push unit.

[0017] The second technical solution adopted in this invention is a flexible support method for gas extraction boreholes to prevent collapse. This method utilizes the aforementioned device and involves the following steps: Step 1: During drilling, monitor and record the borehole condition, identify easily collapsed sections, and number them from deep to shallow. Step 2: After drilling is completed, pack the assembled flexible grid reinforcement support bag and grouting material into a deep-hole grouting drill rod and insert it into the deepest easily collapsed borehole area. Step 3: Push the flexible grid reinforcement support bag to a predetermined position and squeeze it to inject grout, causing the flexible grid reinforcement support bag to expand and adhere to the borehole wall. Step 4: After filling, automatically disconnect the connection; after the grout solidifies to form support, withdraw the deep-hole grouting drill rod. Step 5: Repeat the operation from deep to shallow to complete the full borehole support.

[0018] The second technical solution of the present invention is further characterized by: Step 1 specifically involves: during the deep hole drilling process, real-time monitoring and recording of drilling parameters and the state inside the hole, dynamic analysis to determine the key sections inside the hole that are prone to collapse, and sequentially numbering each area prone to collapse in order from deep to shallow. Step 2 is as follows: After the drilling is completed, the drill rod is removed from the hole, and the quick-connect device of the flexible grid grouting support bag is sealed and connected to the quick-connect outlet of the grouting material package, and then installed into the deep hole grouting drill rod. Then the original drill bit is removed and replaced with a deep hole grouting drill rod, which is sent into the first easily collapsed hole area with the deepest number by the drilling machine. Step 3 specifically involves: slowly retracting the deep hole grouting drill rod within the easily collapsed borehole area, while simultaneously transmitting control signals to the deep hole grouting drill rod via the drilling rig and cable-driven drill rod to drive its internal power pushing unit to push the flexible grid reinforcement support bag to a predetermined position within the borehole; subsequently, the movable bottom plug of the grouting material package is squeezed, causing the first easily ruptured sealed diaphragm and the second easily ruptured sealed diaphragm within the grouting material package to rupture sequentially. After the catalyst and liquid resin are fully mixed, the mixed slurry is continuously injected into the flexible grid reinforcement support bag, causing the flexible grid reinforcement support bag to gradually expand and form effective support for the borehole wall; Step 4 is as follows: When the grout in the flexible grid grouting support bag is filled with grout, the burst valve at the outlet of the grouting material bag is ruptured under pressure, causing the flexible grid grouting support bag to automatically separate from the grouting material bag; then the liquid resin in the flexible grid grouting support bag solidifies rapidly, forming a stable support for the borehole, and the deep hole grouting drill rod is withdrawn. Step 5 specifically involves repeating the operations from Step 2 to Step 4, applying flexible support to each easily collapsible area within the borehole in descending order of depth, until the entire borehole is reinforced with flexible support.

[0019] The beneficial effects of this invention are: This invention addresses several pain points in existing coal mine gas drainage boreholes, including poor coal and rock strata stability leading to borehole collapse, low positioning accuracy of deep-hole support, contradictions between support structures and gas drainage channels, cumbersome and inefficient operation procedures, and poor controllability of grouting operations. Through an integrated design of a flexible support device for preventing borehole collapse and a corresponding segmented fixed-point support method, it achieves integrated, automated, and precise flexible support for easily collapsible sections of gas drainage boreholes. By using a double-cavity flexible grid with a breathable grid to reinforce the support bag, it simultaneously achieves multiple functions such as full-circumference flexible support of the borehole wall, free gas flow, heat insulation, shock absorption, and safety protection. This resolves the technical contradiction of traditional support methods that cannot simultaneously achieve support effectiveness and gas drainage flow. By combining pre-packaged self-controlled grouting material packages with integrated deep-hole grouting drill rods, a closed-loop operation is achieved, encompassing deep-hole pinpoint pushing, self-controlled mixed grouting, and constant-pressure automatic disconnection. This eliminates the need for on-site grout preparation and external grouting pumps, significantly simplifying deep-hole support procedures, improving positioning accuracy and construction efficiency, and adapting to continuous support operations in multiple sections of boreholes from deep to shallow under complex ground stress and mining disturbance environments. It effectively suppresses borehole deformation and collapse, ensures long-term continuous unobstructed gas extraction channels, significantly extends borehole service life, and improves gas extraction efficiency and mine safety. It possesses strong engineering applicability and application value. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the flexible support device for preventing collapse of gas extraction boreholes according to the present invention. Figure 2 This is a schematic diagram of the flexible grid injection support bag in the flexible support device for preventing collapse of gas extraction boreholes of the present invention. Figure 3 yes Figure 2 A schematic diagram of the cross-sectional structure; Figure 4 This is a schematic diagram of the grouting material package in the flexible support device for preventing collapse of gas extraction boreholes of the present invention; Figure 5 This is a schematic diagram of the drill rod structure in the flexible support device for preventing collapse of gas extraction boreholes of the present invention; In the diagram: 1. Flexible grid reinforcement support bag; 1-1. Quick-connect device; 1-2. Ventilation grid; 1-3. One-way valve; 1-4. Top layer; 1-5. Middle layer; 1-6. Bottom layer; 1-7. Second cavity; 1-8. First cavity; 2. Grouting material package; 2-1. First chamber; 2-2. Second chamber; 2-3. Third chamber; 2-4. First easily ruptured sealed diaphragm; 2-5. Second easily ruptured sealed diaphragm; 2-6. Outlet quick-connect; 2-7. Bursting valve; 2-8. Movable bottom plug; 3. Deep hole grouting drill rod; 3-1. Flexible grid reinforcement support bag storage unit; 3-2. Grouting material package storage unit; 3-3. Microprocessor; 3-4. Communication unit; 3-5. Power push unit; 3-6. Power supply unit; 3-7. Central rotary rod; 3-8. Grouting material package extrusion disc. Detailed Implementation

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

[0022] Example 1 like Figure 1-5 As shown in the figure, the flexible support device for gas drainage borehole collapse prevention disclosed in this embodiment includes a deep hole grouting drill rod 3. The deep hole grouting drill rod 3 has a flexible grid reinforcement support bag 1 and a grouting material package 2 inside. The inlet of the flexible grid reinforcement support bag 1 and the outlet of the grouting material package 2 are detachably connected. The deep hole grouting drill rod 3 is used to transport the flexible grid reinforcement support bag 1 and the grouting material package 2 to the target support position of the borehole and complete the grouting support operation.

[0023] In this embodiment, the pre-connected flexible grid reinforcement support bag 1 and grouting material package 2 are integrated and pre-assembled into one unit using a deep-hole grouting drill rod 3. This unit can be directly delivered to the target support position deep within the borehole, replacing the existing separate operation mode of first lowering the support bag and then connecting the grouting pipeline. This embodiment overcomes the engineering and technical pain points of the existing separate bag support, such as insufficient deep-hole positioning accuracy, redundant construction procedures, and failure of support components after borehole collapse. It realizes the pre-assembly and integration of support components and the fixed-point delivery in the deep hole, significantly reducing the construction procedures for deep-hole support, improving the positioning accuracy and construction efficiency of support operations, and providing core structural support for the stable support of easily collapsed sections of gas drainage boreholes.

[0024] Example 2 Based on Example 1, the flexible grid injection support bag 1 is a flame-retardant and antistatic polymer elastic material used in underground coal mines; the main body of the flexible grid injection support bag 1 consists of a bottom layer 1-6, a middle layer 1-5 and a top layer 1-4 stacked in sequence; the bottom layer 1-6 and the middle layer 1-5 enclose a first cavity 1-8, and the middle layer 1-5 and the top layer 1-4 enclose a second cavity 1-7; the bottom layer 1-6, the middle layer 1-5 and the top layer 1-4 are made of the same material and are integrally formed by a one-time molding process.

[0025] Furthermore, the body of the flexible grid injection support bag 1 is a grid structure, and the flexible grid injection support bag 1 has several permeable grids 1-2 that allow coal seam gas to pass through; the first end of the flexible grid injection support bag 1 is provided with an inlet that communicates with the first cavity 1-8, the first cavity 1-8 is used to inject solidifiable grouting material to expand and support the hole wall, and the second cavity 1-7 is filled with heat insulation and shock absorption material.

[0026] In this embodiment, the flexible grid-insulated support bag 1 is made of a standard flame-retardant and antistatic polymer elastic material for underground coal mines, meeting the mandatory safety requirements for equipment entering the mine. The three-layer structure is integrally formed through a one-time molding process, ensuring the overall sealing and structural consistency of the dual-cavity structure and avoiding the risks of fluid leakage and sealing failure in the cavities of the separate adhesive structure. The permeable grids 1-2 arranged in the grid structure form a continuous gas seepage channel while the support bag expands and adheres to the borehole wall to form full-circumference support, thus solving the technical contradiction between the support effectiveness and gas flowability of traditional support structures. In the independent design of the dual cavities, the first cavity 1-8 is the grouting bearing cavity, used to inject curable grouting material to achieve expansion support. The second cavity 1-7 is a heat insulation buffer cavity, and the heat insulation and shock-absorbing material filled inside can isolate the curing reaction heat of the grouting material, avoiding direct contact between the reaction heat and the coal body to induce the risk of spontaneous combustion of the coal seam. At the same time, it can buffer the impact load of the borehole wall collapse, avoiding the failure of the support structure due to impact. This embodiment overcomes the technical problems of existing rigid supports being unable to adapt to coal and rock creep deformation, ordinary bag supports blocking gas extraction channels, grouting curing reaction heat easily inducing safety hazards, and insufficient impact load resistance of support structures. It integrates four core functions: flexible support, gas flow, heat insulation and shock absorption, and safety compliance. It can not only conform to the borehole wall throughout the entire process through elastic deformation, adapt to coal and rock creep deformation and continuously provide stable support force, effectively suppressing borehole deformation and collapse, but also completely does not block the gas extraction path. At the same time, it significantly improves the safety of support operations and the service life of support structures.

[0027] Example 3 Based on Example 2, a quick-connect device 1-1 is fixedly installed at the entrance of the flexible grid grouting support bag 1, and a one-way valve 1-3 is connected in series at the rear end of the quick-connect device 1-1; the one-way valve 1-3 is directed from the grouting material package 2 to the inside of the first cavity 1-8, and is used to block the backflow of grout during the grouting process.

[0028] The quick-connect device 1-1 in this embodiment enables rapid coaxial sealing connection between the flexible grid reinforcement support bag 1 and the grouting material package 2, reducing the operational difficulty of downhole pre-assembly and ensuring the sealing performance of the grouting passage. The one-way valve 1-3 connected in series at the rear end of the quick-connect device 1-1 adopts a one-way conduction structure, limiting the conduction direction to the grouting material package 2 to the first cavity 1-8. It automatically locks after grouting is completed, forming a reverse grout-stopping barrier. This embodiment overcomes the engineering problems existing in current deep hole grouting operations, such as grout backflow and runoff leading to defects in the support body formation, as well as poor sealing of the grouting passage and low operation efficiency. It significantly improves the reliability of grouting operations, ensures that the grouting pressure in the flexible grid reinforcement support bag 1 meets the standard, and can fully expand and fit against the borehole wall to form effective support. At the same time, it simplifies the downhole assembly process of support components, structurally avoids construction failures such as grout blockage in the drill pipe caused by grout backflow, and ensures the continuous and smooth progress of support operations.

[0029] Example 4 Based on Example 3, the grouting material package 2 is an integrated liquid packaging system. The interior of the grouting material package 2 is divided into three independent chambers: a first chamber 2-1, a second chamber 2-2, and a third chamber 2-3, by a ruptureable sealing diaphragm. The first chamber 2-1 and the second chamber 2-2 are separated by a first ruptureable sealing diaphragm 2-4, and the second chamber 2-2 and the third chamber 2-3 are separated by a second ruptureable sealing diaphragm 2-5. The first chamber 2-1 stores a curing time regulating catalyst, the second chamber 2-2 stores liquid resin, and the third chamber 2-3 is a mixing chamber connected to the outlet.

[0030] Furthermore, an outlet quick connector 2-6 is fixedly installed at the outlet of the grouting material package 2, and the outlet quick connector 2-6 is adapted to and sealed with the quick connector device 1-1 of the flexible grid grouting support bag 1; a burst valve 2-7 is also installed at the outlet of the grouting material package 2, and the set burst pressure of the burst valve 2-7 matches the rated filling pressure of the flexible grid grouting support bag 1.

[0031] In this embodiment, the grouting material package 2 adopts a diaphragm-type compartmentalized pre-sealed structure. Under normal conditions, the catalyst and liquid resin components are stored in sealed containers in the first chamber 2-1 and the second chamber 2-2, respectively, to ensure the storage stability of the two-component grouting material and avoid the risk of premature curing failure during pre-loading and transportation. When subjected to axial compressive load, the first easily ruptured sealed diaphragm 2-4 and the second easily ruptured sealed diaphragm 2-5 rupture sequentially according to the set pressure, and the two-component materials enter the third chamber 2-3 to complete turbulent mixing, ensuring the uniformity of the curing reaction and the controllability of the curing time. The quick-connect fitting 2-6 at the outlet is precisely matched with the quick-connect device 1-1 of the flexible grid grouting support bag 1 to achieve rapid sealing and docking. The burst valve 2-7 at the outlet is a constant pressure opening and closing structure. The set burst pressure matches the rated filling pressure of the flexible grid grouting support bag 1 to achieve automatic determination of the grouting endpoint and automatic disconnection of the grouting passage. This embodiment overcomes the technical problems of existing two-component grouting materials, such as low on-site mixing accuracy, uncontrollable curing time, inaccurate control of deep hole grouting endpoint, and easy occurrence of under-grouting support failure or over-grouting blockage. It realizes the pre-encapsulation of grouting materials, self-controlled mixing and constant pressure automatic grouting cut-off, eliminating the need for on-site grouting downhole, significantly reducing the operation process, ensuring the accuracy of grout mixing and controllability of curing time, and accurately controlling the grouting endpoint to ensure that the flexible grid grouting support bag 1 fully expands while avoiding over-grouting, thereby improving the automation level of support operation and the stability of support quality.

[0032] Example 5 Based on Example 4, the grouting material package 2 is a cylindrical packaging structure. A movable bottom plug 2-8 that can move axially is provided at the bottom of the end of the grouting material package 2 opposite to the outlet. The movable bottom plug 2-8 is used to push the material inside the grouting material package 2 to flow to the outlet when subjected to axial compression.

[0033] In this embodiment, the grouting material package 2 adopts a cylindrical packaging structure, which is adapted to the radial dimension of the inner cavity of the deep hole grouting drill rod 3, ensuring coaxiality and smoothness of the axial pushing process and avoiding pushing jamming failure. The movable bottom plug 2-8 set at the end opposite to the outlet is a piston-type axial moving structure. When subjected to axial extrusion load, it moves smoothly along the inner cavity of the grouting material package 2, forming a uniform and stable static pressure thrust on the material in the cavity, and sequentially completing the diaphragm rupture, material mixing and continuous grout injection. This embodiment overcomes the problem of uncontrollable grouting pressure. At the same time, the cylindrical structure fits perfectly with the inner cavity of the deep hole grouting drill rod 3, improving the smoothness of the pre-installation and pushing of the support components.

[0034] Example 6 Based on Example 5, the deep hole grouting drill rod 3 integrates a flexible grid grouting support bag storage unit 3-1, a grouting material package storage unit 3-2, a microprocessor 3-3, a communication unit 3-4, a power pushing unit 3-5, and a power supply unit 3-6 inside the rod body; The power pushing unit 3-5 includes a central rotating rod 3-7 and a grouting material pack extrusion disc 3-8 arranged coaxially along the axis of the deep hole grouting drill rod 3; the rear end of the central rotating rod 3-7 is connected to the drive module of the power pushing unit 3-5, and the front end of the central rotating rod 3-7 faces the discharge port of the deep hole grouting drill rod 3. The flexible grid grouting support bag storage unit 3-1 is used to pre-load the flexible grid grouting support bag 1 to be deployed, and the grouting material bag storage unit 3-2 is used to pre-load the grouting material bag 2 after docking. The grouting material bag storage unit 3-2 and the central rotary rod 3-7 are connected through a transmission structure and move axially along the deep hole grouting drill rod 3. The central rotary rod 3-7 is coaxially inserted into the hollow structure in the middle of the grouting material bag storage unit 3-2 and the grouting material bag 2. The grouting material bag extrusion disc 3-8 is fitted onto the rod body of the central rotary rod 3-7 through an internal thread structure, located at the rear end of the grouting material bag storage unit 3-2, and is axially aligned with the movable bottom plug 2-8 of the grouting material bag 2. The communication unit 3-4 is used to receive external control signals and transmit them to the microprocessor 3-3. After processing the signals, the microprocessor 3-3 sends execution instructions to the power push unit 3-5. The power supply unit 3-6 supplies power to the aforementioned microprocessor 3-3, communication unit 3-4, and power push unit 3-5.

[0035] Based on Example 5, this embodiment utilizes two independent units: a flexible grid reinforcement support bag storage unit 3-1 and a grouting material package storage unit 3-2. These units pre-assemble and connect the flexible grid reinforcement support bag 1 and the grouting material package 2, respectively, achieving integrated pre-assembly of the support components and meeting the requirements for single-drilling support operations. The communication unit 3-4 can stably connect to the mine cable drill rod, enabling remote signal transmission from the ground / drilling rig control panel. The microprocessor 3-3 processes the received control signals and sends precise execution commands to the power push unit 3-5. The power push unit 3-5 uses a coaxially arranged central rotating rod 3-7 to connect with the grouting material package. The grout pack extrusion disc 3-8 is the core actuator. When the central rotary rod 3-7 rotates, it first drives the grout pack storage unit 3-2 to move forward axially through transmission, simultaneously pushing the flexible grid grouting support bag 1 completely from the front end of the deep hole grouting drill rod 3 to the predetermined support position of the borehole. Then, through threaded connection, it drives the grout pack extrusion disc 3-8 to move forward axially, precisely pushing the movable bottom plug 2-8 of the grout pack 2 to complete the extrusion grouting operation, realizing a step-by-step automated operation of first fixed-point pushing and then stable grouting. The independent power supply unit 3-6 provides stable power to each electrical module, ensuring the reliable operation of the electrical system during deep hole operation. This embodiment overcomes the core technical pain points of existing deep hole support operations, such as the inability to achieve step-by-step automated continuous operation, the need for multiple tripping and drilling for multi-section support, low positioning accuracy, high degree of manual intervention, and high operational safety risks. It realizes full-process automation and remote controllability of support operations in easily collapsed sections of gas drainage boreholes. A single borehole entry can complete the entire process of fixed-point pushing, squeezing grouting, and automatic grout cut-off, significantly improving the positioning accuracy and construction efficiency of deep hole support, reducing downhole operation safety risks, and perfectly adapting to the fixed-point support needs of multi-section and batch drilling under complex geostress conditions. It comprehensively ensures the structural stability of the entire section of gas drainage boreholes, effectively extends the effective service life of the borehole, and improves the continuity and efficiency of gas drainage. It has strong engineering applicability and promotion value.

[0036] The working principle of this invention is as follows: During the deep hole drilling construction of gas extraction, the easily collapsed hole sections are first identified and numbered from deep to shallow through monitoring data. After the drilling is completed, the quick-connect device 1-1 at the inlet of the flexible grid grouting support bag 1 is sealed and connected to the quick-connect device 2-6 at the outlet of the grouting material bag 2. Then, the two are pre-installed into the flexible grid grouting support bag storage unit 3-1 and the grouting material bag storage unit 3-2 of the deep hole grouting drill rod 3, so that the central rotating rod 3-7 of the deep hole grouting drill rod 3 is coaxially inserted into the hollow structure in the middle of the grouting material bag 2. Subsequently, the deep hole grouting drill rod 3 is connected to the mine cable drill rod and sent into the deepest target easily collapsed hole section by the drilling rig; in the target section While the deep hole grouting drill rod 3 is slowly retracting, a remote control signal is sent to the deep hole grouting drill rod 3 via the cable drill rod. The signal is received by the communication unit 3-4 and transmitted to the microprocessor 3-3 for analysis and processing. The microprocessor 3-3 then sends an execution command to the power push unit 3-5, driving the central rotary rod 3-7 to rotate. First, through transmission, the grouting material package storage unit 3-2 is moved forward axially, simultaneously pushing the flexible grid grouting support bag 1 completely from the front end of the deep hole grouting drill rod 3 to the predetermined support position in the borehole. After being pushed into place, the central rotary rod 3-7 continues to rotate, driving the grouting material package extrusion disc 3-8 to move forward along the rod thread, precisely pushing the movable bottom plug 2 of the grouting material package 2. Eight pairs of internal chambers form axial static pressure, causing the first easily ruptured sealed diaphragm 2-4 and the second easily ruptured sealed diaphragm 2-5 to rupture sequentially at a set pressure. The curing time regulating catalyst in the first chamber 2-1 and the liquid resin in the second chamber 2-2 enter the third chamber 2-3 to complete uniform mixing. The mixed slurry is continuously injected into the first chamber 1-8 of the flexible grid injection support bag 1 through the docking passage and one-way valve 1-3, causing the flexible grid injection support bag 1 to expand radially until it fully conforms to the borehole wall. During this process, the heat insulation and shock absorption material in the second chamber 1-7 isolates the heat of slurry curing reaction from direct contact with the coal body, while buffering the impact load of borehole wall collapse. The breathable grid 1-2 of the bag retains continuous gas. The seepage channel prevents the support structure from blocking the gas extraction path. When the grout in the first chamber 1-8 is full and the grouting pressure rises to the set blasting pressure of the blasting valve 2-7, the blasting valve 2-7 ruptures under pressure, realizing the automatic separation of the flexible grid reinforcement support bag 1 and the grouting material package 2. At the same time, the one-way valve 1-3 automatically locks to block the reverse flow of grout. After the mixed grout in the first chamber 1-8 is completely solidified, a permanent flexible support structure adapted to the creep deformation of coal and rock is formed. Then, the deep hole grouting drill rod 3 is withdrawn, and the above operation process is repeated in the order from deep to shallow to complete the full-section flexible reinforcement of all easily collapsed sections in the borehole. Finally, the core goal of suppressing borehole collapse and ensuring the continuous and unobstructed gas extraction channel is achieved.

[0037] The present invention provides a flexible support method for preventing collapse of gas drainage boreholes, comprising the following steps: Step 1 specifically involves: During the drilling of deep boreholes for gas drainage, a measurement-while-drilling (MWD) system is used to collect and record in real-time drilling parameters such as drilling pressure, rotation speed, feed rate, and torque, as well as borehole three-dimensional trajectory parameters, borehole wall coal and rock integrity, and borehole surrounding rock stress state, along with the borehole's internal conditions. The collected data is transmitted in real-time to the ground / drilling rig control panel via the mine cable drill pipe. Based on the real-time monitoring data, combined with the target coal seam geological exploration data and coal and rock physical and mechanical parameters, the system dynamically analyzes and determines weak sections within the borehole that have poor coal and rock stability, are greatly affected by mining disturbances, and are prone to collapse. The starting and ending depths, section lengths, and surrounding rock characteristics of each easily collapsed section are accurately marked. All identified easily collapsed sections within the borehole are sequentially numbered from deep to shallow, forming a borehole support section positioning ledger. This provides accurate depth positioning data for subsequent segmented support, preventing support failure caused by support position deviations.

[0038] Step 2 specifically involves: After drilling to the designed final hole depth, stopping drilling operations and completely removing all conventional drilling rods from the hole; completing the pre-installation and connection of support components in the explosion-proof safety area downhole: aligning the quick-connect device 1-1 at the inlet of the flexible grid grouting support bag 1 with the quick-connect outlet 2-6 at the outlet of the grouting material bag 2 coaxially and tightening them to seal, completing the pre-connection of the flexible grid grouting support bag 1 and the grouting material bag 2, ensuring the grouting passage is sealed and leak-free; inserting the pre-connected grouting material bag 2 into the grouting material bag storage unit 3-2 of the deep hole grouting drill rod 3, and inserting the flexible grid grouting support bag 1 into the flexible grid grouting support bag storage unit 3-2 of the deep hole grouting drill rod 3. Within Yuan 3-1, during the pre-installation process, ensure that the central rotating rod 3-7 of the deep hole grouting drill rod 3 is coaxially inserted into the hollow structure in the middle of the grouting material package 2, and that the grouting material package extrusion disc 3-8 and the movable bottom plug 2-8 of the grouting material package 2 are axially aligned without deviation; remove the conventional drill bit used for drilling construction, and coaxially fix the tail end of the deep hole grouting drill rod 3 to the mine cable drill rod, complete the joint debugging test of the communication and power systems, and after confirming that the signal transmission and power execution are normal, drive the cable drill rod through the drilling rig to smoothly feed the deep hole grouting drill rod 3 along the borehole axis until the front discharge port of the deep hole grouting drill rod 3 accurately reaches the design support starting depth of the first easily collapsed section with the deepest number.

[0039] Step 3 is as follows: After the deep hole grouting drill rod 3 is positioned, it is slowly retracted at a set uniform speed of 0.5-1 m / min within the target easily collapsed section. During the retraction, a remote control signal is sent from the drilling rig control panel to the deep hole grouting drill rod 3 via the cable drill rod. The control signal is received by the communication unit 3-4 of the deep hole grouting drill rod 3 and transmitted to the microprocessor 3-3 for parsing and processing. The microprocessor 3-3 sends an execution command to the power push unit 3-5, driving the central rotating rod 3-7 to rotate forward at the set speed. The central rotary rod 3-7 first drives the grouting material package storage unit 3-2 to move smoothly forward along the axial direction of the deep hole grouting drill rod 3 via transmission, simultaneously pushing the docked grouting material package 2 and flexible grid grouting support bag 1 forward, completely pushing the flexible grid grouting support bag 1 out of the discharge port at the front end of the deep hole grouting drill rod 3 and accurately positioning it in the predetermined support position inside the borehole; after positioning, the grouting material package storage unit 3-2 is axially locked, and the central rotary rod 3-7 continues to rotate forward, driving the grouting material package extrusion disc. 3-8 moves smoothly forward along the axial direction of the rod body through the internal thread engagement, continuously pushing the movable bottom plug 2-8 of the grouting material package 2 to apply stable axial static pressure to the internal chamber, causing the first easily ruptureable sealed diaphragm 2-4 and the second easily ruptureable sealed diaphragm 2-5 in the grouting material package 2 to rupture sequentially at the set pressure. The curing time regulating catalyst in the first chamber 2-1 and the liquid resin in the second chamber 2-2 enter the third chamber 2-3 to complete turbulent and uniform mixing; the mixed slurry is continuously injected into the flexible grid through the docking passage and the one-way valve 1-3. Within the first cavity 1-8 of the grid-solidified support bag 1, the flexible grid-solidified support bag 1 expands uniformly along the radial direction of the borehole until the outer wall of the bag is tightly attached to the borehole wall, forming a full-section flexible support. During this process, the heat-insulating and shock-absorbing material in the second cavity 1-7 isolates the heat of the slurry solidification reaction from direct contact with the coal body on the borehole wall, while buffering the impact load of local collapse of the borehole wall. The permeable grid 1-2 of the flexible grid-solidified support bag 1 body forms a continuous gas seepage channel, which retains a complete gas extraction passage while supporting the borehole wall.

[0040] Step 4 is as follows: When the grout in the first cavity 1-8 of the flexible grid grouting support bag 1 is completely filled and the grouting pressure continues to rise to the set burst pressure of the burst valve 2-7, the burst valve 2-7 will rupture under pressure, realizing the automatic separation of the flexible grid grouting support bag 1 and the grouting material package 2, and completing the self-controlled determination of the grouting endpoint; at the same time, the one-way valve 1-3 at the inlet of the flexible grid grouting support bag 1 will automatically lock, forming a reverse grout stop barrier, completely blocking the reverse flow path of the grout, and preventing grout leakage and return failures; keep the borehole stationary for 15-30 minutes, the specific time of which is determined according to the curing time adjusted by the catalyst ratio, and after the mixed grout in the first cavity 1-8 has completely solidified and formed a permanent flexible support structure that can adapt to the creep deformation of coal and rock and continuously provide stable support force, the deep hole grouting drill rod 3 will be smoothly withdrawn from the borehole by driving the cable drill rod through the drilling rig.

[0041] Step 5 is as follows: Following the numbering order of the easily collapsed borehole sections from deep to shallow, repeat the entire process of steps 2 to 4: After each section of support is completed, replace the new flexible grid reinforcement support bag 1 and grouting material package 2 to complete the pre-installation, and then send the deep hole grouting drill rod 3 into the borehole to the next numbered easily collapsed borehole section to complete the flexible support operation of the corresponding section; and so on, until the segmented flexible support of all numbered easily collapsed borehole sections in the borehole is completed, so as to achieve full coverage reinforcement of the easily collapsed borehole area of ​​the entire borehole section; after the full borehole support is completed, the support effect of each support section is detected and verified by the borehole imaging instrument. After confirming that the support structure is intact and the borehole wall is properly attached, clean the borehole opening, connect the gas extraction pipeline, and officially start the gas extraction operation.

[0042] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0043] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0044] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A flexible support device for preventing collapse of gas drainage boreholes, characterized in that, The system includes a deep hole grouting drill rod (3), which contains a flexible grid grouting support bag (1) and a grouting material package (2). The inlet of the flexible grid grouting support bag (1) and the outlet of the grouting material package (2) are detachably connected. The deep hole grouting drill rod (3) is used to transport the flexible grid grouting support bag (1) and the grouting material package (2) to the target support position of the borehole and complete the grouting support operation.

2. The flexible support device for preventing collapse of gas drainage boreholes according to claim 1, characterized in that, The flexible grid injection support bag (1) is a flame-retardant and antistatic polymer elastic material used in underground coal mines; the main body of the flexible grid injection support bag (1) consists of a bottom layer (1-6), a middle layer (1-5) and a top layer (1-4) stacked in sequence; the bottom layer (1-6) and the middle layer (1-5) enclose to form a first cavity (1-8), and the middle layer (1-5) and the top layer (1-4) enclose to form a second cavity (1-7); the bottom layer (1-6), the middle layer (1-5) and the top layer (1-4) are made of the same material and are integrally formed by a one-time molding process.

3. The flexible support device for preventing collapse of gas extraction boreholes according to claim 2, characterized in that, The body of the flexible grid injection support bag (1) is a grid structure. The flexible grid injection support bag (1) has several permeable grids (1-2) that allow coal seam gas to pass through. The first end of the flexible grid injection support bag (1) has an inlet that communicates with the first cavity (1-8). The first cavity (1-8) is used to inject solidifiable grouting material to expand and support the hole wall. The second cavity (1-7) is filled with heat insulation and shock absorption material.

4. The flexible support device for preventing collapse of gas drainage boreholes according to claim 3, characterized in that, A quick-connect device (1-1) is fixedly installed at the entrance of the flexible grid grouting support bag (1), and a one-way valve (1-3) is connected in series at the rear end of the quick-connect device (1-1); the one-way valve (1-3) is directed from the grouting material bag (2) to the inside of the first cavity (1-8) to block the backflow of grout during the grouting process.

5. The flexible support device for preventing collapse of gas drainage boreholes according to claim 4, characterized in that, The grouting material package (2) is an integrated liquid packaging system. The interior of the grouting material package (2) is divided into a first chamber (2-1), a second chamber (2-2), and a third chamber (2-3) by a ruptureable sealing diaphragm. The first chamber (2-1) and the second chamber (2-2) are separated by a first ruptureable sealing diaphragm (2-4), and the second chamber (2-2) and the third chamber (2-3) are separated by a second ruptureable sealing diaphragm (2-5). The first chamber (2-1) stores a curing time regulating catalyst, the second chamber (2-2) stores liquid resin, and the third chamber (2-3) is a mixing chamber connected to the outlet.

6. The flexible support device for preventing collapse of gas drainage boreholes according to claim 5, characterized in that, The outlet of the grouting material package (2) is fixedly provided with an outlet quick connector (2-6), which is adapted to and sealed with the quick connector (1-1) of the flexible grid grouting support bag (1); the outlet of the grouting material package (2) is also equipped with a burst valve (2-7), and the set burst pressure of the burst valve (2-7) is matched with the rated filling pressure of the flexible grid grouting support bag (1).

7. The flexible support device for preventing collapse of gas drainage boreholes according to claim 6, characterized in that, The grouting material package (2) is a cylindrical packaging structure. A movable bottom plug (2-8) that can move axially is provided at the bottom of the end of the grouting material package (2) opposite to the outlet. The movable bottom plug (2-8) is used to push the material inside the grouting material package (2) to flow to the outlet when subjected to axial compression.

8. The flexible support device for preventing collapse of gas drainage boreholes according to claim 7, characterized in that, The deep hole grouting drill rod (3) integrates a flexible grid grouting support bag storage unit (3-1), a grouting material package storage unit (3-2), a microprocessor (3-3), a communication unit (3-4), a power push unit (3-5), and a power supply unit (3-6) inside the rod body. The power push unit (3-5) includes a central rotary rod (3-7) and a grouting material pack extrusion disc (3-8) arranged coaxially along the axis of the deep hole grouting drill rod (3); the rear end of the central rotary rod (3-7) is connected to the drive module of the power push unit (3-5) for transmission, and the front end of the central rotary rod (3-7) faces the discharge port of the deep hole grouting drill rod (3); The flexible grid grouting support bag storage unit (3-1) is used to pre-load the flexible grid grouting support bag (1) to be deployed, and the grouting material bag storage unit (3-2) is used to pre-load the grouting material bag (2) after docking. The grouting material bag storage unit (3-2) and the central rotary rod (3-7) are connected by a transmission structure and move axially along the deep hole grouting drill rod (3). The central rotary rod (3-7) is coaxially inserted into the hollow structure in the middle of the grouting material bag storage unit (3-2) and the grouting material bag (2). The grouting material bag extrusion disc (3-8) is fitted onto the rod of the central rotary rod (3-7) through an internal thread structure. It is located at the rear end of the grouting material bag storage unit (3-2) and is axially aligned with the movable bottom plug (2-8) of the grouting material bag (2). The communication unit (3-4) is used to receive external control signals and transmit them to the microprocessor (3-3). After processing the signals, the microprocessor (3-3) sends execution instructions to the power push unit (3-5). The power supply unit (3-6) supplies power to the aforementioned microprocessor (3-3), communication unit (3-4), and power push unit (3-5).

9. A flexible support method for preventing collapse of gas drainage boreholes, characterized in that, The device according to any one of claims 1 to 8 is used for implementation, and the steps are as follows: Step 1, during drilling, the state inside the hole is monitored and recorded, and the easily collapsed sections are identified and numbered from deep to shallow; Step 2, after drilling is completed, the connected flexible grid grouting support bag (1) and grouting material bag (2) are loaded into the deep hole grouting drill rod (3) and sent into the deepest easily collapsed area; Step 3, the flexible grid grouting support bag (1) is pushed to the predetermined position and squeezed to inject grout, so that the flexible grid grouting support bag (1) expands and fits the hole wall; Step 4, after filling, the connection is automatically disconnected, and after the grout solidifies to form support, the deep hole grouting drill rod (3) is withdrawn; Step 5, the operation is repeated from deep to shallow to complete the full hole support.

10. The flexible support method for preventing collapse of gas drainage boreholes according to claim 9, characterized in that: Step 1 specifically involves: during the deep hole drilling process, real-time monitoring and recording of drilling parameters and the state inside the hole, dynamic analysis to determine the key sections inside the hole that are prone to collapse, and sequentially numbering each area prone to collapse in order from deep to shallow. Step 2 is as follows: After the drilling is completed, the drill rod is removed from the hole, and the quick-connect device (1-1) of the flexible grid grouting support bag (1) is sealed and connected with the quick-connect device (2-6) of the outlet of the grouting material bag (2), and then installed into the deep hole grouting drill rod (3); then the original drilling bit is removed and replaced with the deep hole grouting drill rod (3), and sent into the first easily collapsed hole area with the deepest number by the drilling machine; Step 3 is as follows: Slowly retract the deep hole grouting drill rod (3) in the area of ​​easy-to-collapse hole, and at the same time transmit control signals to the deep hole grouting drill rod (3) through the drilling machine and the cable drill rod to drive its internal power push unit (3-5) to push the flexible grid grouting support bag (1) to the predetermined position in the borehole; then squeeze the movable bottom plug (2-8) of the grouting material package (2) to make the first easily ruptureable sealed diaphragm (2-4) and the second easily ruptureable sealed diaphragm (2-5) in the grouting material package (2) rupture in sequence. After the catalyst and liquid resin are fully mixed, the mixed slurry is continuously injected into the flexible grid grouting support bag (1) so that the flexible grid grouting support bag (1) gradually expands and forms effective support for the hole wall; Step 4 is as follows: When the grout in the flexible grid grouting support bag (1) is filled with grout, the burst valve (2-7) at the outlet of the grouting material bag (2) is ruptured under pressure, causing the flexible grid grouting support bag (1) to automatically separate from the grouting material bag (2); then the liquid resin in the flexible grid grouting support bag (1) solidifies rapidly, forming a stable support for the borehole, and the deep hole grouting drill rod (3) is withdrawn. Step 5 specifically involves repeating the operations from Step 2 to Step 4, applying flexible support to each easily collapsible area within the borehole in descending order of depth, until the entire borehole is reinforced with flexible support.

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