Self-pressure broken anchor rod for coal mine underground outburst prevention and use method thereof

Abstract

This invention provides a self-pressurizing anchor bolt for coal mine outburst prevention and its usage method in the field of underground coal mines. The bolt includes: a connector, a head rod, a middle rod assembly, and a tail rod. The middle rod assembly is positioned between the head and tail rods, and the head, middle, and tail rods are connected in a straight line. One end of the head rod has a concave groove arranged radially along its length. The middle rod assembly includes at least one middle section rod, with concave grooves at both ends of each middle section rod. The tail rod's connection end with the middle rod assembly has a concave groove. A connector is provided between two adjacent concave grooves. The connector includes a rod body and an insert rod, with insert rods at both ends of the rod body, which are assembled with the concave grooves. The head, tail, and middle rods are made of metal, while the connector is made of plastic. This invention solves the problems of slag shedding, spalling, and high risk of coal and gas outbursts in working faces with soft stratification.

Description

Technical Field

[0001] This invention relates to the field of underground coal mining, and provides a self-pressurizing anchor bolt for preventing coal mine outbursts and its usage method. Background Technology

[0002] Coal is the primary energy source. With the continuous increase in coal seam mining depth, coal and gas outburst hazards in deep coal seam mining are becoming increasingly serious, and coal and gas outbursts have become a major bottleneck restricting efficient and safe production in coal mines. Pre-drainage of gas from coal seam tunneling and longwall faces is the main technical measure to prevent coal and gas outbursts. However, conventional borehole drainage is ineffective and involves a large amount of work, and cannot completely eliminate the risk of coal and gas outbursts, leading to frequent occurrences of dynamic phenomena such as face spalling after treatment.

[0003] Coal and gas outbursts are primarily caused by the low strength and easy deformation of stratified coal seams. When the working face advances into areas containing stratified coal seams, these seams are prone to failure first, leading to overall working face instability and triggering coal and gas outbursts. Therefore, strengthening stratified coal seams and increasing their support capacity is crucial for coal and gas outburst prevention. Currently, technical measures for strengthening the coal seam in tunneling and longwall mining faces mainly include coal seam grouting and metal skeletons. Coal seam grouting requires drilling at the working face, injecting grout into the borehole, and waiting for the grout to solidify before the working face can be cut and advanced. This process consumes a significant amount of manpower, resources, and time. Metal skeletons are mainly used for coal and gas outburst prevention during the rock face uncovering process. If applied to longwall and tunneling faces, large metal components must be manually cleaned, significantly impacting the cutting speed.

[0004] Therefore, existing devices for strengthening coal body cannot effectively meet the needs of coal cutting and coal and gas outburst prevention in both tunneling and mining faces during actual use. They cannot improve the strength of the coal body in the working face without affecting the coal cutting speed. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a self-pressurizing anchor bolt for coal mine outburst prevention and its application method, solving the challenges of slag shedding, spalling, and high risk of coal and gas outbursts in working faces with soft stratification. Specifically, it includes:

[0006] A self-pressurizing anchor bolt for preventing coal mine outbursts includes: a connector, a head rod, a middle rod group, and a tail rod, wherein the middle rod group is disposed between the head rod and the tail rod, and the head rod, the middle rod group, and the tail rod are connected in a straight line.

[0007] One end of the head rod is connected to the anchoring machine, and the other end of the head rod is provided with an inwardly recessed groove arranged radially along the head rod.

[0008] The middle rod assembly includes at least one middle rod body, and each middle rod body has concave rod grooves at both ends;

[0009] The connection end between the tail rod and the middle rod assembly is provided with a concave rod groove;

[0010] The diameters of the head rod, the tail rod, and the middle rod are equal.

[0011] A connector is provided between two adjacent concave rod grooves. The connector includes a rod body and a plug rod. Plug rods are provided at both ends of the rod body, and the plug rods are assembled with the concave rod grooves.

[0012] The head rod, tail rod, and middle rod are made of metal, and the compressive strength of the connector meets the following requirements:

[0013]

[0014] Where σ0 is the original geostress of the coal seam, σ p This represents the peak stress caused by mining disturbance.

[0015] Optionally, the head rod, the tail rod, and the middle rod are of equal length, and the length of the head rod is equal to the distance the loader excavates in one operation.

[0016] Optionally, the head rod is made of steel reinforcement.

[0017] Optionally, the number of middle-section rods in the middle-end rod group is n, where n≥1;

[0018] The number of connectors is n+1.

[0019] Optionally, the connection end between the head rod and the anchoring machine is threaded.

[0020] Optionally, the connector is used to connect two adjacent concave rod grooves by casting.

[0021] A method for using a self-pressurizing anchor bolt for coal mine outburst prevention, comprising the aforementioned self-pressurizing anchor bolt for coal mine outburst prevention, and further comprising:

[0022] When the working face requires anchoring, the anchoring machine anchors the self-pressurizing breakable anchor bolts for coal mine outburst prevention to the target position.

[0023] Each connector in the self-pressurizing anchor bolt for coal mine outburst prevention deforms under the action of the top plate and bottom plate of the working face, and each connector completely detaches from the self-pressurizing anchor bolt for coal mine outburst prevention.

[0024] As the working face continues to advance, the head rod, the middle rod group, and the tail rod are exposed in sequence, among which the connecting parts used to connect the head rod, the middle rod group, and the tail rod are exposed in sequence.

[0025] Optionally, the situations requiring anchoring include:

[0026] Scenario 1: Soft coal stratification occurs at the working face;

[0027] Scenario 2: Slab formation occurs at the working face;

[0028] Scenario 3: Slag falls off the working surface.

[0029] Optionally, the target location is the location where the situation requiring anchoring occurs;

[0030] When the self-pressurizing anchor bolt for coal mine outburst prevention is inserted into the target position, the self-pressurizing anchor bolt for coal mine outburst prevention is parallel to the top plate of the working face.

[0031] Optionally, the number of self-pressurizing anchor bolts used for preventing coal mine outbursts at the target location is at least one.

[0032] The above technical solution has at least the following advantages compared with the existing technology:

[0033] This invention increases the support capacity of soft coal strata in coal mining and tunneling faces, reducing the damage caused by mining disturbances. It reduces the deformation of soft coal strata, increases the support capacity of the coal body in the pressure relief zone, and effectively solves the problems of coal face spalling and slag shedding during face advancement, thus reducing the risk of coal and gas outbursts. While enhancing the strength of soft coal strata and reducing the risk of coal and gas outbursts, it does not affect the progress of the coal mining face.

[0034] This invention solves the problems of slag shedding, spalling, and high risk of coal and gas outbursts when working faces encounter soft stratification. It improves the low support strength of working faces when encountering soft coal stratification in underground coal mines, which helps to improve the control effect of coal and gas outburst prevention and control and reduce the control cost of coal and gas outburst prevention and control in underground coal mines. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of the self-pressurizing anchor bolt provided by the present invention;

[0037] Figure 2 End view of the head rod and connector provided for this invention;

[0038] Figure 3 This is a schematic diagram of the operation of the self-pressurizing anchor bolt provided by the present invention.

[0039] Figure label:

[0040] 1. Head rod; 2. Connector; 3. Middle rod; 4. Tail rod; 5. Hard coal stratification; 6. Soft coal stratification; 7. Top plate; 8. Bottom plate; 101. Thread; 102. Inward concave rod groove end face; 201. Insert rod. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0042] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising,” “including,” or “including,” and similar terms mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or “connected,” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0043] It should be noted that the terms "up", "down", "left", "right", "front", and "back" used in this invention are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0044] like Figure 1 As shown, this embodiment provides a self-pressurizing anchor bolt for coal mine outburst prevention and its application method in the first aspect, solving the problems of high risk of coal and gas outbursts in working faces with soft stratification, slag shedding, and rockfall. Specifically, it includes:

[0045] A self-pressurizing anchor bolt for preventing coal mine outbursts includes: a connector 2, a head rod 1, a middle rod assembly, and a tail rod 4. The middle rod assembly is positioned between the head rod 1 and the tail rod 4, and the head rod 1, middle rod assembly, and tail rod 4 are connected in a straight line. One end of the head rod 1 is connected to an anchoring machine, and the other end of the head rod 1 has a concave groove arranged radially along the head rod 1. The middle rod assembly includes at least one middle section rod 3, and each middle section rod 3 has concave grooves at both ends. The tail rod 4 and the middle rod assembly are connected by a concave groove; the diameters of the head rod 1, the tail rod 4, and the middle rod 3 are equal, and a connector 2 is provided between two adjacent concave grooves 102. The connector 2 includes a rod body and an insert rod 201. Insert rods 201 are provided at both ends of the rod body, and the insert rods 201 are assembled with the concave grooves 102; the head rod 1, the tail rod 4, and the middle rod 3 are made of metal, and the compressive strength P of the connector satisfies:

[0046]

[0047] Where σ0 is the original geostress of the coal seam, σ p This represents the peak stress caused by mining disturbance.

[0048] The connectors can be made of metal or plastic, such as cast iron, aluminum alloy, polycarbonate (PC), nylon (PA), etc.

[0049] The specific structure of the self-pressurizing anchor bolt provided in this embodiment is as follows:

[0050] The head rod 1 is a metal rod. One end of the head rod 1 is threaded 101 and is used to connect to the anchoring machine. The other end of the head rod 1 has a concave groove 102 in the middle of its end face.

[0051] The connector 2 has the same diameter as the head rod 1. Both ends of the connector 2 have a raised section in the middle, which is a insertion rod 201. The length of the insertion rod 201 is equal to the length of the concave rod groove 102 and its shape is compatible. The connector 2 is made of plastic. The head rod 1, the middle rod assembly, and the tail rod 4 can be fixed in a mold. The shape and function of the mold can be set according to actual needs. The purpose is to fix the head rod 1, the middle rod assembly, and the tail rod 4 sequentially. The middle rod assembly includes multiple or... One middle section rod 3, the central axis of all the rods is on a straight line, there is a certain distance between two adjacent rods, and each distance is equal. Since each middle section rod 3 has a concave rod groove 102 at both ends, and the connecting section between the head rod 1 and the middle section rod 3 and the connecting section between the tail rod 4 and the middle section rod 3 are also provided with concave rod grooves 102, plastic casting liquid is poured into the mold, and after the casting liquid solidifies, it forms a connector 2. The connector 2 is connected to the concave rod groove 102 by the adhesion of the solidified material.

[0052] In one specific implementation, the head rod 1, the tail rod 4, and the middle rod 3 are of equal length, and the length of the head rod 1 is equal to the distance the loader can excavate in one operation.

[0053] In one specific implementation, the head rod 1, the middle rod 3, and the tail rod 4 are reinforced with steel bars.

[0054] In one specific implementation, the number of middle section rods 3 in the middle rod group is n, where n≥1; the number of connectors 2 is n+1.

[0055] When there are two middle rods 3 in the middle rod group, there are three connectors 2. The self-pressurizing anchor rods from the head to the tail are arranged as follows: head rod 1 - connector 2 - middle rod 3 - connector 2 - middle rod 3 - connector 2 - tail rod 4.

[0056] When there is one middle section rod 3 in the middle rod group, the self-pressurized breakage anchor rod from the head to the tail is set as follows: head rod 1-connector 2-middle section rod 3-connector 2-tail rod 4.

[0057] When there are 3 middle section rods 3 in the middle section rod group, the self-pressurized breakage anchor rods from the head to the tail are arranged as follows: head rod 1-connector 2-middle section rod 3-connector 2-middle section rod 3-connector 2-middle section rod 3-connector 2-tail rod 4.

[0058] When the number of middle rods 3 in the middle rod group is m, the sequence is: head rod 1 - connector 2 - [m groups (m middle rods 3 - connector 2)] - tail rod 4.

[0059] In one specific implementation, the connection end between the head rod 1 and the anchoring machine is provided with thread 101.

[0060] Since the connector 2 is made of plastic and is cast and connected in the concave rod groove 102, and the head rod 1, middle rod 3 and tail rod 4 are made of steel bars, the strength of the connector 2 is less than the strength of the head rod 1, middle rod 3 and tail rod 4.

[0061] Therefore, when the self-pressurizing anchor bolt is installed in the soft coal layer 6 or at the target location, due to the disturbance caused by the working face, the ground stress of the coal seam in the area in front of the working face is higher than the compressive strength P of the connector 2. In this area, the self-pressurizing anchor bolt will break in two forms.

[0062] like Figure 3 As shown, fracture mode 1 occurs when the stress in the coal seam of the area exceeds the compressive strength P of the connector 2, causing the contact surface between the head rod 1 and the connector 2 to separate, resulting in self-pressure breakage of the anchor rod; fracture mode 2 occurs when the stress in the connector 2 exceeds its compressive strength P, causing it to break, resulting in self-pressure breakage of the anchor rod.

[0063] This self-pressurizing anchor bolt increases the support capacity of the soft coal stratum 6 in the coal mining and tunneling face, reducing the damage caused by mining disturbances. It reduces the deformation of the soft coal stratum 6, increases the support capacity of the coal body in the pressure relief zone of the working face, and effectively solves the problems of coal wall spalling and slag shedding during face advancement, reducing the risk of coal and gas outbursts. While enhancing the strength of the soft coal stratum 6 and reducing the risk of coal and gas outbursts, it does not affect the progress of the coal mining face.

[0064] This self-pressurizing anchor bolt solves the problems of slag shedding, spalling, and high risk of coal and gas outbursts when the working face encounters soft strata. It improves the low support strength of the working face when encountering soft coal strata in underground coal mines, helps to improve the control effect of coal and gas outburst prevention and control, and reduces the control cost of coal and gas outburst prevention and control in underground coal mines.

[0065] The present invention also provides a method for using a self-pressurizing anchor bolt for coal mine outburst prevention, comprising the aforementioned self-pressurizing anchor bolt for coal mine outburst prevention, and further comprising:

[0066] When the working face requires anchoring, the anchoring machine anchors the self-pressurizing breakable anchor bolts for coal mine outburst prevention to the target position.

[0067] Each connector 2 in the self-pressurizing anchor bolt for coal mine outburst prevention deforms under the action of the top plate 7 and the bottom plate 8 of the working face, and each connector 2 completely detaches from the self-pressurizing anchor bolt for coal mine outburst prevention.

[0068] As the working face continues to advance, the head rod 1, the middle rod group, and the tail rod 4 are exposed in sequence, among which the connecting piece 2 used to connect the head rod 1, the middle rod group, and the tail rod 4 are exposed in sequence.

[0069] like Figure 3 As shown, the working environment of this self-pressurizing anchor bolt is underground in a coal mine. The roof plate 7 is the top of the roadway, and the bottom plate 8 is the bottom of the roadway. On the working face, from the roof plate 7 to the bottom plate 8, hard coal layer 5 and soft coal layer 6 are set in sequence. When the working face finds a situation that requires anchoring during the excavation, this device needs to be installed at the target position by the anchoring machine.

[0070] The situations requiring anchoring include:

[0071] Scenario 1: Soft coal stratification occurs at the working face;

[0072] Scenario 2: Slab formation occurs at the working face;

[0073] Scenario 3: Slag falls off the working surface.

[0074] The target location is the location where the situation requiring anchoring occurs;

[0075] When the self-pressurizing anchor bolt for coal mine outburst prevention is inserted into the target position, the self-pressurizing anchor bolt is parallel to the roof 7 of the working face. At least one self-pressurizing anchor bolt is anchored at the target position.

[0076] The specific principle behind this method is as follows:

[0077] When the working face encounters soft coal strata 6 or when the working face shows signs of spalling or slag falling, multiple of these devices are anchored to the soft coal strata 6 of the working face using an anchoring machine.

[0078] After the device is anchored to the soft layer, under the influence of the stress concentration caused by the mining disturbance of the top plate 7 and bottom plate 8 of the working face, the connector 2 in the anchor rod undergoes large deformation and separates from the head rod 1, the middle rod 3 and the tail rod 4.

[0079] The device breaks the coal body into a head rod 1, a connector 2, a middle rod 3, and a tail rod 4.

[0080] As the tunnel face continues to advance, the head rod 1, connector 2, middle rod 3, and tail rod 4 are gradually exposed and extracted;

[0081] After the broken head rod 1 is extracted, a new anti-outburst self-pressurizing anchor rod is anchored with an anchoring machine, so that the tunneling face alternately passes through the soft coal strata 6.

[0082] This method can increase the support capacity of soft coal strata 6 in coal mining and tunneling faces, and reduce the degree of damage caused by mining disturbances. It reduces the deformation of soft coal strata 6, increases the support capacity of the coal body in the pressure relief zone of the working face, and effectively solves the problems of coal wall spalling and slag shedding during working face advancement, thus reducing the risk of coal and gas outbursts. While enhancing the strength of soft coal strata 6 and reducing the risk of coal and gas outbursts, it does not affect the progress of the coal mining face.

[0083] This method solves the problems of slag shedding, spalling, and high risk of coal and gas outbursts when working faces encounter soft strata. It improves the low support strength of working faces when encountering soft coal strata in underground coal mines, and helps to improve the control effect of coal and gas outburst prevention and control, and reduce the control cost of coal and gas outburst prevention and control in underground coal mines.

[0084] The following points need to be explained:

[0085] (1) The accompanying drawings of the embodiments of the present invention only involve the structures involved in the embodiments of the present invention. Other structures can refer to the general design.

[0086] (2) For clarity, the thickness of layers or regions is enlarged or reduced in the drawings used to describe embodiments of the present invention; that is, these drawings are not drawn to actual scale. It is understood that when an element such as a layer, film, region, or substrate is referred to as being “above” or “below” another element, the element may be “directly” located “above” or “below” the other element, or there may be intermediate elements.

[0087] (3) Where there is no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to obtain new embodiments.

[0088] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A self-pressurizing anchor bolt for preventing coal mine outbursts, characterized in that, include: The device comprises a connector, a head rod, a middle rod assembly, and a tail rod, wherein the middle rod assembly is disposed between the head rod and the tail rod, and the head rod, the middle rod assembly, and the tail rod are connected in a straight line. One end of the head rod is connected to the anchoring machine, and the other end of the head rod is provided with an inwardly recessed groove arranged radially along the head rod. The middle rod assembly includes at least one middle rod body, and each middle rod body has concave rod grooves at both ends; The connection end between the tail rod and the middle rod assembly is provided with a concave rod groove; The diameters of the head rod, the tail rod, and the middle rod are equal. A connector is provided between two adjacent concave rod grooves. The connector includes a rod body and a plug rod. Plug rods are provided at both ends of the rod body, and the plug rods are assembled with the concave rod grooves. The head rod, tail rod, and middle rod are made of metal, and the compressive strength P of the connector satisfies: ; in, The original geostress of the coal seam, This represents the peak stress caused by mining disturbance. When a self-pressurizing anchor bolt is installed at the target location, due to the disturbance caused by mining at the working face, the in-situ stress of the coal seam in a certain area in front of the working face is higher than the compressive strength P of the connector. In this area, the contact surface between the head of the self-pressurizing anchor bolt and the connector separates, and the self-pressurizing anchor bolt breaks.

2. The self-pressurizing anchor bolt for preventing coal mine outbursts according to claim 1, characterized in that, The head rod, the tail rod, and the middle rod are of equal length, and the length of the head rod is equal to the distance the loader can excavate in one operation.

3. The self-pressurizing anchor bolt for preventing coal mine outbursts according to claim 1, characterized in that, The head rod is made of steel bars.

4. The self-pressurizing anchor bolt for preventing coal mine outbursts according to claim 3, characterized in that, The number of middle-section rods in the middle-end rod group is n, where n≥1; The number of connectors is n+1.

5. The self-pressurizing anchor bolt for preventing coal mine outbursts according to claim 1, characterized in that, The connection between the head rod and the anchoring machine is threaded.

6. The self-pressurizing anchor bolt for preventing coal mine outbursts according to claim 1, characterized in that, The connector is formed by casting two adjacent concave rod grooves.

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