WO2024212507A1 - Plugging structure and system for drainage holes in gas tunnel - Google Patents

Abstract

A plugging structure for drainage holes (20) in a gas tunnel. A sealing layer (100) is provided on a gas drainage pending surface of the gas tunnel, and openings of the drainage holes (20) are arranged in the sealing layer (100) and communicated with a formed area of the gas tunnel; then drainage pipes (200) are inserted into the drainage holes (20), and the pipe opening at one end of each drainage pipe (200) extends out of the drainage hole (20); then a hole sealing mechanism (300) is wrapped around the periphery of each drainage pipe (200), and then a plugging mechanism is plugged in each drainage hole (20). The plugging structure for the drainage holes (20) in the gas tunnel can plug the gas drainage holes (20), and after plugging, it can be effectively ensured that gas cannot escape from the drainage holes (20). Also provided is a plugging system for the drainage holes (20) in the gas tunnel.

Description

Gas tunnel drainage hole plugging structure and system

This application claims priority to Chinese patent application No. 202310433742.2 filed on April 13, 2023, the entire contents of which are incorporated by reference into this application.

Technical Field

The present application relates to the technical field of gas tunnel construction, and in particular to a drainage hole sealing structure and system for a gas tunnel.

Background Art

At present, there are many kinds of gas extraction drilling sealing technologies in China, mainly using cement mortar, high molecular polyester, two belts and one injection and other sealing technologies. The sealing of extraction holes is mainly due to improper selection of sealing technology, sealing materials, and sealing length, poor grouting and plugging of cracks between holes, etc., resulting in poor sealing quality; improper arrangement of the sequence before and after construction drilling, the sequence of sealing grouting, and unreasonable arrangement of sealing construction sequence, etc., which cause disturbances to the completed sealing, resulting in the formation of new fracture channels in the drilling sealing section and around the drilling hole; at the same time, after the free gas in the coal body is extracted, the coal body shrinks and forms splitting cracks. These reasons lead to poor sealing effect of extraction holes, and the extraction has a great impact on efficiency. At the same time, after the extraction hole is formed, due to the soft coal seam, the formed extraction hole may cause necking, collapse, and coal ash falling into the extraction hole, resulting in the extraction hole under negative pressure. The hole is more likely to collapse and block the channel, resulting in poor stability of the extraction hole and affecting the extraction effect.

Technical issues

The main purpose of the present application is to provide a drainage hole sealing structure and system for a gas tunnel, aiming to solve the technical problem that after the drainage hole is formed in the related technology, due to the soft coal seam, the formed drainage hole may cause necking, collapse, and coal ash may fall into the drainage hole, causing the drainage hole to collapse and block the hole under negative pressure, resulting in poor stability of the drainage hole and affecting the drainage effect.

Technical Solutions

To achieve the above-mentioned purpose, in a first aspect, the present application provides a drainage hole plugging structure for a gas tunnel, wherein the drainage hole is arranged in a coal seam of the gas tunnel;

The drainage hole blocking structure comprises:

A sealing layer, wherein the sealing layer is arranged on the gas to-be-extracted surface of the gas tunnel, and the orifice of the extraction hole is arranged on the sealing layer and communicated with the formed area of the gas tunnel;

a pumping pipe, wherein the pumping pipe is inserted into the pumping hole, and one end of the pumping pipe extends out of the pumping hole; and

A sealing mechanism, which is coated on the outer circumference of the drainage pipe and seals the drainage hole. The sealing mechanism includes a first sealing portion and a second sealing portion which are arranged in sequence and at intervals from the orifice of the drainage hole toward the inside of the drainage hole, and a cavity is formed between the first sealing portion and the second sealing portion. Both the first sealing portion and the second sealing portion can expand and fill the drainage hole to seal the drainage hole.

In one embodiment, the first blocking portion includes a first blocking layer and a first expansion layer, the first blocking layer fills the opening of the drainage hole, the first expansion layer expands and fills the drainage hole, and the first expansion layer abuts against one side of the first blocking layer located in the drainage hole.

In one embodiment, the second expansion section includes a second expansion layer and a second blocking layer arranged in sequence, the second expansion layer expands and fills the drainage hole, and the second expansion layer is arranged opposite to the first expansion layer with the cavity formed therebetween, and the second blocking layer fills the drainage hole.

In one embodiment, the drainage hole blocking structure further includes an exhaust pipe extending from the opening of the drainage hole through the first blocking portion and to the highest position in the cavity, wherein the exhaust pipe connects the cavity with the formed area of the gas tunnel.

In one embodiment, the drainage hole sealing structure also includes a grouting pipe that passes through the first sealing portion from the orifice of the drainage hole and extends to the lowest position in the cavity, the grouting pipe connects the cavity with an external grouting device, and the external grouting device injects cement slurry into the cavity through the grouting pipe, and the cement slurry can be filled from the lowest position to the highest position, and the gas in the cavity is discharged from the exhaust pipe.

In one embodiment, the cement slurry includes water and cement, wherein the mix ratio of water to cement is water:cement=1:1.

In one embodiment, an expansion agent is further added to the cement slurry, wherein the amount of the expansion agent is 2.5% of the amount of the cement.

In one embodiment, a polycarboxylic acid high-efficiency water-reducing agent and a retarder are further added to the cement slurry, wherein the amount of the polycarboxylic acid high-efficiency water-reducing agent is 1% of the amount of the cement, and the amount of the retarder is 1.8% of the amount of the cement.

In one embodiment, the sealing layer includes a sealing concrete layer and a reinforcement layer, the sealing concrete layer is arranged on the gas extraction surface, and the orifice of the extraction hole is arranged on the sealing concrete layer, and the reinforcement layer is arranged on the outer surface of the sealing concrete layer.

Based on the same technical concept, in the second aspect, the present application proposes a drainage hole sealing system for a gas tunnel, comprising a drainage construction surface and at least two drainage hole sealing structures as described in the first aspect, wherein at least two of the drainage hole sealing structures are spaced apart and distributed on the drainage construction surface.

Beneficial Effects

The technical solution of the present application is to set a sealing layer, a drainage pipe and a sealing mechanism, and the sealing layer is set on the gas surface to be extracted in the gas tunnel. The orifice of the drainage hole is arranged in the sealing layer and is connected with the formed area of the gas tunnel. The drainage pipe is inserted into the drainage hole, and one end of the drainage pipe is extended out of the drainage hole. The sealing mechanism is coated on the outer periphery of the drainage pipe, and the sealing mechanism is sealed in the drainage hole. The sealing mechanism includes a first sealing part and a second sealing part which are arranged in sequence and at intervals from the orifice of the drainage hole toward the inside of the drainage hole. The first sealing part and the second sealing part can both expand and fill the drainage hole. A cavity is formed between the first sealing part and the second sealing part. The technical solution of the present application is to set a sealing layer on the gas surface to be extracted in the gas tunnel, and the drainage hole is arranged in the sealing layer. The orifice of the hole is arranged in the sealing layer and connected with the formed area of the gas tunnel. Then the extraction pipe is inserted into the extraction hole, and the pipe mouth of one end of the extraction pipe extends out of the extraction hole. Then the sealing mechanism is coated on the outer periphery of the extraction pipe, and the sealing mechanism is sealed in the extraction hole. Therefore, the present application can seal the gas extraction hole during specific implementation, and after sealing, it can also effectively ensure that the gas will not overflow from the extraction hole. This solves the technical problem that after the extraction hole is formed, due to the soft coal seam, the formed extraction hole may shrink, collapse, and coal ash may fall into the extraction hole, which makes the extraction hole more likely to collapse and block the channel under negative pressure, resulting in poor stability of the extraction hole and affecting the extraction effect.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

FIG1 is a schematic structural diagram of a gas extraction hole blocking structure of an example of an embodiment of the present application;

FIG2 is an enlarged structural schematic diagram of part A in FIG1 ;

FIG3 is a schematic plan view of a blocking layer according to an example of the present application;

FIG4 is a schematic diagram of the side structure of the plugging layer of the present application example;

FIG5 is a schematic diagram of the arrangement of the extraction holes of the present application example;

FIG6 is a schematic diagram of the blocking principle of the polyurethane material used in the present application;

FIG. 7 is a schematic diagram of the structure of the drainage hole plugging system of the present application example.

Description of the drawings:

10 Coal seam 312 First expansion layer 100 Sealing layer 321 Second expansion layer 200 Extraction pipe 322 Second sealing layer 300 Sealing mechanism 330 Exhaust pipe 310 The first sealing part 340 Grouting pipe 320 Second sealing part 110 Concrete sealing layer 311 The first sealing layer 120 Reinforcement layer 20 Extraction hole 130 Sleeve valve tube

The purpose, features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings.

Embodiments of the present invention

The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various mechanisms under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and/or" appearing in the full text includes three parallel schemes. Taking "A and/or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

The inventive concept of the present application is further explained below in conjunction with some specific implementation methods.

The present application proposes a sealing structure and system for a gas extraction hole 20 of a gas tunnel.

As shown in FIG. 1 to FIG. 7 , an embodiment of the sealing structure and system of the extraction hole 20 of the gas tunnel of the present application is proposed.

In this embodiment, please refer to FIG. 1 to FIG. 7 , the drainage hole 20 blocking structure of this type of gas tunnel, the drainage hole 20 is arranged in the coal seam 10 of the gas tunnel;

The sealing structure of the extraction hole 20 includes:

A sealing layer 100, the sealing layer 100 is arranged on the gas to-be-extracted surface of the gas tunnel, and the orifice of the extraction hole 20 is arranged on the sealing layer 100 and communicated with the formed area of the gas tunnel;

A drainage pipe 200, the drainage pipe 200 is inserted into the drainage hole 20, and one end of the drainage pipe 200 extends out of the drainage hole 20; and,

The sealing mechanism 300 is coated on the outer circumference of the exhaust pipe 200, and the sealing mechanism 300 is sealed in the exhaust hole 20. The sealing mechanism includes a first sealing portion 310 and a second sealing portion 320 which are arranged in sequence and at intervals from the orifice of the exhaust hole 20 toward the hole of the exhaust hole 20, and a cavity is formed between the first sealing portion 310 and the second sealing portion 320. Both the first sealing portion 310 and the second sealing portion 320 can expand and fill the exhaust hole 20 to seal the exhaust hole 20.

It should be particularly and clearly stated that, in this embodiment, the sealing layer 100 is preferably formed by spraying airtight concrete on the gas to be extracted and discharged surface. At the same time, considering that the cracks and other channels in the geological body in the unexcavated area behind the gas to be extracted and discharged surface are easy to cause gas overflow, therefore, in the specific implementation, the geological body can be reinforced according to the geological conditions. When reinforcing the geological body, the sleeve valve pipe 130 grouting or fracturing grouting can be used to reinforce the geological body, but it is not limited to. In addition, after the spraying construction of the airtight concrete layer is completed, in order to improve the stability and safety of the sealing layer 100, it is also necessary to construct a steel frame on the surface of the airtight concrete layer. When constructing the steel frame, it is necessary to fix the end of the steel frame to the corresponding position of the junction of the formed section of the gas tunnel and the gas to be extracted and discharged surface, thereby achieving the improvement of the stability of the entire steel frame and the sealing layer 100, avoiding the hidden danger of gas leakage caused by the protrusion of the coal seam 10 or the protrusion of the geological body during the gas extraction or cutting of the coal seam 10.

In the present embodiment, by providing a sealing layer 100, a drainage pipe 200 and a sealing mechanism 300, the sealing layer 100 is arranged on the gas to-be-extracted surface of the gas tunnel, the orifice of the drainage hole 20 is arranged on the sealing layer 100 and is connected to the formed area of the gas tunnel, the drainage pipe 200 is inserted into the drainage hole 20, and one end of the drainage pipe 200 extends out of the drainage hole 20, the sealing mechanism 300 is coated on the outer periphery of the drainage pipe 200, and the sealing mechanism 300 is blocked in the drainage hole 20, the blocking mechanism includes a first blocking portion 310 and a second blocking portion 320 which are sequentially and spacedly arranged from the orifice of the drainage hole 20 toward the inside of the drainage hole 20, the first blocking portion 310 and the second blocking portion 320 can both expand and fill the drainage hole 20, a cavity is formed between the first blocking portion 310 and the second blocking portion 320, and the present application is provided by sealing the drainage hole 20 in the gas tunnel. A sealing layer 100 is set on the surface to be drained, and the orifice of the drainage hole 20 is arranged in the sealing layer 100 and connected with the formed area of the gas tunnel, and then the drainage pipe 200 is inserted into the drainage hole 20, and the pipe mouth of one end of the drainage pipe 200 extends out of the drainage hole 20, and then the sealing mechanism 300 is coated on the outer periphery of the drainage pipe 200, and then the sealing mechanism is blocked in the drainage hole 20, so that the present application can block the gas drainage hole 20 during specific implementation, and after blocking, it can also effectively ensure that the gas will not overflow from the drainage hole 20, which solves the technical problem that after the extraction hole is formed, due to the soft coal seam 10, the formed extraction hole may cause necking, collapse, and coal ash falls into the extraction hole, which makes the extraction hole more prone to collapse and blockage under negative pressure, resulting in poor stability of the extraction hole and affecting the extraction effect.

In some specific embodiments, the first blocking portion 310 includes a first blocking layer 311 and a first expansion layer 312. The first blocking layer 311 fills the opening of the drainage hole 20, the first expansion layer 312 expands and fills the drainage hole 20, and the first expansion layer 312 abuts against one side of the first blocking layer 311 located in the drainage hole 20.

In this embodiment, by providing the first blocking layer 311 and the first expansion layer 312 on the first blocking portion 310 , the present application can block the drainage hole 20 during implementation, thereby avoiding the risk of gas overflowing from the cracks in the drainage hole 20 .

It should be particularly and clearly stated that, in this embodiment, the first sealing layer 311 is preferably made of bagged polyurethane, and the first expansion layer 312 is preferably made of an expansion waterstop strip. In specific implementation, the expansion waterstop strip is a waterstop strip that expands 40 times when exposed to water.

In some specific embodiments, the second expansion section includes a second expansion layer 321 and a second blocking layer 322 arranged in sequence, the second expansion layer 321 expands and fills the pumping hole 20, and the second expansion layer 321 is arranged opposite to the first expansion layer 312 and a cavity is formed therebetween, and the second blocking layer 322 fills the pumping hole 20.

In this embodiment, by providing the first sealing layer 311 and the second expansion layer 321 in the second sealing portion 320, the present application can seal the drainage hole 20 for a second time during implementation, thereby further improving the sealing effect of the drainage hole 20 and further avoiding the risk of gas overflowing from the cracks in the drainage hole 20.

It should be particularly and clearly stated that, in this embodiment, the second sealing layer 322 is preferably made of bagged polyurethane, and the second expansion layer 321 is preferably made of an expansion waterstop strip. In specific implementation, the expansion waterstop strip is a waterstop strip that expands 40 times when exposed to water.

In some specific embodiments, the sealing structure of the drainage hole 20 further includes an exhaust pipe 330 extending from the opening of the drainage hole 20 through the first sealing portion 310 and to the highest position in the cavity, and the exhaust pipe 330 connects the cavity with the formed area of the gas tunnel.

In this embodiment, a highest position is formed in the cavity, an exhaust pipe 330 is arranged, and the exhaust pipe 330 is passed through the first blocking portion 310 and the pipe mouth at one end of the exhaust pipe 330 is placed in the highest position, so that the gas in the cavity can be discharged during the specific implementation of the present application.

In some specific embodiments, the sealing structure of the drainage hole 20 also includes a grouting pipe 340 that passes through the first sealing portion 310 from the opening of the drainage hole 20 and extends to the lowest position in the cavity. The grouting pipe 340 connects the cavity with an external grouting device. The external grouting device injects cement slurry into the cavity through the grouting pipe 340, and the cement slurry can be filled from the lowest position to the highest position, and the gas in the cavity is discharged from the exhaust pipe 330.

In this embodiment, a lowest position is formed in the cavity, and the grouting pipe 340 is passed through the first sealing portion 310 and the pipe mouth at one end of the grouting pipe 340 is placed in the lowest position, and then the sealing slurry is injected into the cavity through the grouting pipe 340. When the present application is implemented, it can cooperate with the exhaust pipe 330 set at the highest position to discharge the gas in the cavity, and the injected sealing slurry can also be filled from the lowest position to the highest position, thereby further improving the sealing effect of the exhaust hole 20.

It should be particularly and clearly stated that, in this embodiment, the grouting slurry used as an example may be, but is not limited to, a cement slurry with a cement: water ratio of 1:1, and other slurries that can achieve the grouting and sealing function, such as epoxy resin, etc. may also be used.

In some specific embodiments, the cement slurry includes water and cement, wherein the mix ratio of water to cement is water:cement=1:1.

In this embodiment, during specific implementation, the mix ratio of water:cement can be adjusted accordingly.

In this embodiment, the cement slurry is set to water: cement with a mix ratio of 1:1, so that the filling effect of the cavity can be ensured during the specific implementation of the present application.

In some specific embodiments, an expansion agent is further added to the cement slurry, wherein the amount of the expansion agent is 2.5% of the amount of cement.

In this embodiment, during specific implementation, the actual dosage can be adjusted according to experiments in actual use.

In some specific embodiments, polycarboxylic acid high-efficiency water-reducing agent and retarder are further added to the cement slurry, wherein the amount of polycarboxylic acid high-efficiency water-reducing agent is 1% of the amount of cement, and the amount of retarder is 1.8% of the amount of cement.

In this embodiment, the parameters of the high-efficiency water reducing agent and the retarder are adjusted in the actual construction according to the test results of the trial mixing.

In some specific embodiments, the sealing layer 100 includes a sealing concrete layer 110 and a reinforcement layer 120 . The sealing concrete layer 110 is disposed on the surface where gas is to be extracted, and the orifice of the extraction hole 20 is arranged on the sealing concrete layer 110 . The reinforcement layer 120 is disposed on the outer surface of the sealing concrete layer 110 .

It should be particularly and clearly stated that, in this embodiment, the sealing concrete layer 110 is preferably made of airtight concrete spraying. At the same time, considering that the cracks and other channels in the geological body in the unexcavated area behind the gas extraction surface are prone to cause gas overflow, the geological body can be reinforced according to the geological conditions during the specific implementation. When reinforcing the geological body, the sleeve valve pipe 130 grouting or fracturing grouting can be used to reinforce the geological body, but it is not limited to. In addition, after the spraying construction of the airtight concrete layer is completed, in order to improve the stability and safety of the sealing layer 100, it is also necessary to construct a steel frame on the surface of the airtight concrete layer. When constructing the steel frame, it is necessary to fix the end of the steel frame to the corresponding position of the junction of the formed section of the gas tunnel and the gas extraction surface, thereby achieving the improvement of the stability of the entire steel frame and the sealing layer 100, avoiding the hidden danger of gas leakage caused by the protrusion of the coal seam 10 or the protrusion of the geological body during the gas extraction or cutting of the coal seam 10.

Based on the same technical concept, in the second aspect, the present application proposes a drainage hole 20 plugging system for a gas tunnel, comprising a drainage construction surface and at least two drainage hole 20 plugging structures of the first aspect, wherein at least two drainage hole 20 plugging structures are spaced apart and distributed on the drainage construction surface.

In some specific embodiments, the present application may also be executed according to the following examples:

After drilling and cleaning the hole with a large diameter drill, the extraction pipe is arranged along the entire length, and a drill hole is arranged on the hole wall at the front end of the extraction pipe to improve the integrity of the extraction hole and solve the problem of poor gas negative pressure distribution and poor flow caused by borehole shrinkage, hole blockage, and obstruction; the sealing length is adjusted for the rock mass within a distance of 10m from the 10th normal line of the coal seam, and the sealing materials and processes at both ends are improved. Micro-expansive cement-based composite grouting materials are used to grout and plug the extraction hole to improve the sealing quality of the extraction hole 20, and improve the high-quality sealing of the front and rear sections of the sealing section. High-pressure grouting can be used The new expansive composite material can not only improve the plugging effect, but also consolidate and plug the rock cracks, surrounding rocks and coal seams, and consolidate the broken rock into a whole stone body wrapped by cement-based slurry without air leakage; at the same time, the C25 airtight concrete is used to seal the face to improve the integrity and stability of the rock mass, and the shotcrete is reinforced with an I-beam to improve the stability of the rock mass and prevent collapse, causing gas leakage in the extraction holes, and prevent safety hazards caused by gas outbursts. When grouting the sealing section, the slurry can be sprayed to block the gap between the concrete and the face. The above measures such as different plugging materials, sealing lengths, and plugging processes can reduce the negative pressure loss during extraction, prevent the air in the tunnel from entering the rock cracks through the face, reduce the negative pressure of extraction, and improve the extraction effect.

In view of the 7.4MPa gas pressure and ultra-high gas concentration (21.99m3/ton of coal) of a certain tunnel, this application is proposed. First, a φ6mm steel mesh is laid on the face, and the spacing between the steel meshes is 25cm*25cm. The horizontal and vertical I14 I-beams outside the steel bars are used to reinforce the shotcrete (to prevent the shotcrete from cracking due to high gas pressure or high grouting pressure). The 20cm thick C25 airtight shotcrete is used to seal the tunnel face. After the shotcrete is completed, according to the opening coordinates, deflection angle and length requirements of the designed extraction holes, the extraction holes are drilled from the arch foot to the arch top, from left to right at the upper step face. After each extraction hole 20 is completed, the full-length extraction pipe is installed. When the extraction pipe is installed, there is 10m left, that is, the extraction holes within 10m of the face are sealed.

The length of the extraction hole is 10m, the sealing length of both ends is 1m, and the middle section is 8m. The front end sealing section is completely wrapped with 40 times water-expandable water stop strips within 10cm longitudinally on the φ20 extraction pipe, and the remaining 90cm of the pipe length is wrapped with bagged polyurethane material and then tied firmly with thin wire. There are 3 pipes within the 1m long range of the rear end, of which the main pipe is φ20 plastic extraction pipe 200, φ20mm galvanized steel pipe and φ10mm soft rubber hose. A layer of 40 times water-expandable water stop strips is wrapped within the 10cm range of the 3 pipes, and the remaining 90cm of the pipe length is wrapped with bagged polyurethane material and tied firmly with prompts; the middle section 8m extraction is not processed. After the processed extraction pipes are installed in sequence into the φ76 extraction borehole, the gaps between the root pipes at the ends are filled with polyurethane, and the part outside the concrete spraying on the 20 galvanized steel pipe exposed on the face is installed with ordinary faucets for grouting. Grouting expansive cement-based materials, making full use of the polyurethane foaming effect, the water stop strip expands rapidly when it encounters water to fill the cavity outside the pipe, and can withstand the advantages of pressure. The 1.5MPa pressure is used for infiltration grouting in the hole. The grouting material is a micro-expansion modified sulphoaluminate cement-based grouting material, and the cracks in the hole and the surrounding rock mass and coal seam 10 are grouted. Grouting is carried out hole by hole from bottom to top, and each grouting pipe is 340 pressure 1.5MPA for 10 minutes. The grouting time is concentrated grouting of the installed extraction holes every 3 days.

S201: A certain tunnel was excavated to 10m from the normal line of the coal seam. After the prediction of coal seam 10 outburst was completed, it was determined that coal seam 10 was an outburst coal seam 10 (C8 coal seam 10 gas pressure 7.4MPa, coal seam 10 gas content 21.99), and outburst prevention was required. A φ6 steel mesh was hung on the face, and vertical and horizontal I14 steel bars were installed on the outside for reinforcement. Two 3m long mortar anchor rods were constructed at the intersection with the initial support and some nodes for fixing. After completion, a 20cm thick C25 airtight sprayed concrete was used to completely seal the face.

Airtight shotcrete is made by adding airtight agent to shotcrete at 2% of the cement content per cubic meter. The airtight agent is in dry powder form and can be added and stirred evenly when mixing the shotcrete.

S202. After the closure is completed, the drilling of the gas extraction hole 20 is started according to the designed opening coordinates, angle of the deflection hole and length of the extraction.

S203, two 4000 hydraulic drilling machines with a drill bit diameter of 76m are used for drilling holes. They are arranged on both sides of the face. The drilling process is skipped to facilitate the installation of the drainage pipe 200. The drilling and installation are staggered and carried out in turns. (Each drilling machine constructs 20 holes per day) After each drainage and cleaning, the full-length drainage pipe 200 is safely installed.

S204. The extraction pipe uses a φ20 hard plastic pipe with a φ4mm plum blossom-shaped hole at the front end of the pipe. The drilling spacing is 30cm, with 2 holes in each ring, which are set opposite to each other. The second ring of holes is staggered, and no holes are processed in the remaining last 12m. The last 10m of the extraction pipe is installed at 200.

S205. At both ends of the remaining 10m of the drainage pipe 200, use AB glue to bond the rubber waterstop strip that has expanded 40 times to the drainage pipe 200 at the front end. The bonding length is 10cm. Wrap it continuously with bagged polyurethane for 90cm and tie it firmly with fine wire. Close to the palm side, tie together a 5m long 25 diameter galvanized steel pipe and a 3m long 10mm soft rubber tube. Tie it firmly with waterstop and bagged polyurethane again according to the signature. After filling the gaps between the 32 pipes with polyurethane, install the drainage pipe 200 in place.

The plugging principle of polyurethane materials - black material (polyol polyether) and white material (polyisocyanate) are prepared in a certain proportion and tied to the gas extraction pipe. During the reaction and expansion of the polyurethane material, when the expansion radius is greater than the borehole radius (that is, R>r), on the one hand, the radial expansion effect of the material itself causes the polyurethane material to be squeezed into the cracks around the borehole; on the other hand, the radial extrusion effect causes the cracks within a certain range around the borehole to close, and finally the polyurethane reaction ends (at this time the expansion radius R'>R), achieving a plugging effect on the cracks within the local range of the borehole.

S206. After the hole pipe is buried, use anchoring agent to block the air in the hole pipe sprayed with concrete, leaving a gap of about 1 cm, and then use cotton yarn and cement mortar or AB glue to seal the hole. After the hole part solidifies, use φ20 ordinary faucet to weld it to the galvanized steel pipe for subsequent grouting.

S207. Install the remaining drainage pipes 200 in sequence. After every three days, perform grouting reinforcement on the installed drainage pipes.

S208, grouting, grouting is carried out in the order from the arch foot to the arch top, and grouting is carried out in a symmetrical order from the center of the section to both sides. The main material of the grouting material is sulphoaluminate ultrafine cement.

The water-cement ratio of cement is 1:1, 2.5% of the cement mass of the expansion agent, 1% of the polycarboxylic acid high-efficiency water-reducing agent, and 1.8% of the retarder are added.

The initial grouting pressure is 0.5MPa. During grouting, clear water and thin slurry are first discharged from the exhaust pipe 330, and then viscous cement is discharged. The exhaust pipe 330 is firmly tied with wire, and grouting is continued until the final pressure is 1.5MPa. After the pressure stabilizes, it can be continued for 10 minutes. After each grouting is completed, the faucet is closed and grouting is carried out for another pipe.

S209. After completing the sealing and grouting reinforcement of the exhaust pipe 200, the gas shall be exhausted as required until the inspection meets the standards.

The technical solution of the present application is to set a sealing layer 100, a drainage pipe 200 and a sealing mechanism 300, and the sealing layer 100 is set on the gas to-be-extracted surface of the gas tunnel, the orifice of the drainage hole 20 is arranged in the sealing layer 100 and is connected with the formed area of the gas tunnel, the drainage pipe 200 is inserted into the drainage hole 20, and one end of the drainage pipe 200 extends out of the drainage hole 20, the sealing mechanism 300 is coated on the outer periphery of the drainage pipe 200, and the sealing mechanism 300 is blocked in the drainage hole 20, and the sealing mechanism includes a first blocking portion 310 and a second blocking portion 320 which are sequentially and spacedly arranged from the orifice of the drainage hole 20 toward the inside of the drainage hole 20, the first blocking portion 310 and the second blocking portion 320 can both expand and fill the drainage hole 20, and a cavity is formed between the first blocking portion 310 and the second blocking portion 320. A sealing layer 100 is set on the surface to be drained, and the orifice of the drainage hole 20 is arranged in the sealing layer 100 and connected with the formed area of the gas tunnel, and then the drainage pipe 200 is inserted into the drainage hole 20, and the pipe mouth of one end of the drainage pipe 200 extends out of the drainage hole 20, and then the sealing mechanism 300 is coated on the outer periphery of the drainage pipe 200, and then the sealing mechanism is blocked in the drainage hole 20, so that the present application can block the gas drainage hole 20 during specific implementation, and after blocking, it can also effectively ensure that the gas will not overflow from the drainage hole 20, which solves the technical problem that after the extraction hole is formed, due to the soft coal seam 10, the formed extraction hole may cause necking, collapse, and coal ash falls into the extraction hole, which makes the extraction hole more prone to collapse and blockage under negative pressure, resulting in poor stability of the extraction hole and affecting the extraction effect.

The above description is only an optional embodiment of the present application, and does not limit the patent scope of the present application. All equivalent structural changes made by using the contents of the present application specification and drawings under the application concept of the present application, or directly/indirectly applied in other related technical fields are included in the patent protection scope of the present application.

Claims (10)

A drainage hole blocking structure for a gas tunnel, wherein the drainage hole is arranged in a coal seam of the gas tunnel; The drainage hole blocking structure comprises: A sealing layer, wherein the sealing layer is arranged on the gas to-be-extracted surface of the gas tunnel, and the orifice of the extraction hole is arranged on the sealing layer and communicated with the formed area of the gas tunnel; a pumping pipe, wherein the pumping pipe is inserted into the pumping hole, and one end of the pumping pipe extends out of the pumping hole; and A sealing mechanism, which is coated on the outer circumference of the drainage pipe and seals the drainage hole. The sealing mechanism includes a first sealing portion and a second sealing portion which are arranged in sequence and at intervals from the orifice of the drainage hole toward the inside of the drainage hole, and a cavity is formed between the first sealing portion and the second sealing portion. Both the first sealing portion and the second sealing portion can expand and fill the drainage hole to seal the drainage hole. The drainage hole sealing structure of a gas tunnel as described in claim 1, wherein the first sealing portion includes a first sealing layer and a first expansion layer, the first sealing layer is filled in the opening of the drainage hole, the first expansion layer is expanded and filled in the drainage hole, and the first expansion layer is abutted against one side of the first sealing layer located in the drainage hole. The drainage hole sealing structure of a gas tunnel as described in claim 2, wherein the second expansion section includes a second expansion layer and a second sealing layer arranged in sequence, the second expansion layer expands and fills the drainage hole, and the second expansion layer is arranged opposite to the first expansion layer and the cavity is formed therebetween, and the second sealing layer fills the drainage hole. The drainage hole sealing structure of a gas tunnel according to claim 1, wherein: The drainage hole blocking structure further includes an exhaust pipe extending from the opening of the drainage hole through the first blocking portion and to the highest position in the cavity, wherein the exhaust pipe connects the cavity with the formed area of the gas tunnel. The drainage hole sealing structure of a gas tunnel as described in claim 4, wherein the drainage hole sealing structure also includes a grouting pipe that passes through the first sealing portion from the orifice of the drainage hole and extends to the lowest position in the cavity, the grouting pipe connects the cavity with an external grouting device, and the external grouting device injects cement slurry into the cavity through the grouting pipe, and the cement slurry can be filled from the lowest position to the highest position, and the gas in the cavity is discharged from the exhaust pipe. The drainage hole sealing structure of a gas tunnel as described in claim 5, wherein the cement slurry comprises water and cement, wherein the mix ratio of water to cement is water:cement=1:1. The drainage hole sealing structure of a gas tunnel as described in claim 6, wherein an expansion agent is further added to the cement slurry, wherein the amount of the expansion agent is 2.5% of the amount of the cement. The drainage hole sealing structure of a gas tunnel as described in claim 6, wherein a polycarboxylic acid high-efficiency water reducer and a retarder are further added to the cement slurry, wherein the amount of the polycarboxylic acid high-efficiency water reducer is 1% of the amount of the cement, and the amount of the retarder is 1.8% of the amount of the cement. The drainage hole sealing structure of a gas tunnel as described in any one of claims 1 to 8, wherein the sealing layer includes a sealing concrete layer and a reinforcement layer, the sealing concrete layer is arranged on the gas to be extracted surface, and the orifice of the drainage hole is arranged in the sealing concrete layer, and the reinforcement layer is arranged on the outer surface of the sealing concrete layer. A drainage hole plugging system for a gas tunnel, comprising a drainage construction surface and at least two drainage hole plugging structures as described in any one of claims 1 to 9, wherein at least two of the drainage hole plugging structures are distributed at intervals on the drainage construction surface.