A downward through-layer drilling reverse blasting outburst elimination method for tunnel outburst coal seam

Abstract

The present application belongs to the field of tunnel gas control, and discloses a downward through-hole drilling reverse blasting outburst elimination method for tunnel outburst coal seam, comprising the following steps: opening two rows of parallel downward extraction drill holes on the coal seam step of the working face; opening a row of blast drill holes with the same arrangement direction in the middle position of the two rows of extraction drill holes, and the blast drill holes are coaxially arranged with the extraction drill holes; performing hydraulic punching on each extraction drill hole and blast drill hole; connecting the extraction drill holes with an extraction pipeline for gas extraction; placing blast columns in each blast drill hole; injecting water into each blast drill hole until the liquid level is higher than the blast column; under the action of blasting, water can enter the pores and fissures of the coal body, avoiding water from blocking the extraction channel, and increasing the water content of the coal body, which can significantly reduce the dust amount in the tunnel excavation process, improve the working environment of the tunnel working face, and effectively utilize the residual water of the hydraulic measure.

Description

Technical Field

[0001] This invention belongs to the field of tunnel gas control, specifically relating to a method for suppressing outbursts by reverse blasting through downward cross-layer drilling in tunnels with coal seams. Background Technology

[0002] With the rapid development of transportation infrastructure in western my country, more and more tunnels are traversing coal-bearing strata, making gas tunnels a challenging aspect of transportation construction. During coal seam exposure, coal and rock masses in high-stress and high-gas environments are highly susceptible to coal and gas outbursts, causing casualties and property damage. To prevent such accidents, it is necessary to preemptively suppress outbursts in the coal seams.

[0003] When encountering a coal seam that is prone to outbursts in a tunnel, the coal seam typically forms a large angle with the tunnel excavation direction. If the tunnel face is located on the roof of the outburst coal seam, all types of outburst prevention boreholes are drilled downwards, making conventional hydraulic outburst suppression measures ineffective. The main reason is that removing slag from downward boreholes is difficult, and the water accumulated in the borehole is hard to drain, potentially blocking the gas extraction channel. Therefore, existing technologies suffer from the problem of residual water easily blocking gas extraction channels after hydraulic outburst suppression. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for suppressing coal seams through downward cross-layer drilling and reverse blasting, which solves the problem in existing technologies where residual water after hydraulic suppression can easily block the gas extraction channel.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for suppressing coal seam outbursts through downward cross-layer drilling with reverse blasting includes the following steps:

[0007] Two rows of downward-facing extraction boreholes are drilled side by side on the coal seam bench.

[0008] A row of blasting boreholes with the same orientation is opened in the middle of the two rows of extraction boreholes, and the blasting boreholes are all placed in the same axis as the extraction boreholes.

[0009] Hydraulic flushing was performed on each extraction borehole and blasting borehole.

[0010] Connect the extraction borehole to the extraction pipeline for gas extraction;

[0011] Each blasting borehole was filled with a blasting charge.

[0012] Water was injected into the blasting boreholes until the liquid level was higher than the explosive charge.

[0013] The blasting borehole is sealed above the liquid surface, and the detonation line is led out of the blasting borehole through the sealed part.

[0014] The explosive charges in each blasting borehole are detonated simultaneously, and the blasting boreholes are then connected to extraction pipelines for gas extraction.

[0015] The diameter of the extraction borehole is 153 mm, and the bottom of the extraction borehole is located at 2 / 3 of the coal seam thickness.

[0016] The two rows of extraction boreholes are placed symmetrically, with a spacing of 5m between them;

[0017] The distance between two adjacent extraction boreholes in each row is 5m.

[0018] The diameter of the blasting borehole is 94mm. The blasting borehole penetrates the coal seam and extends 1m into the bottom plate below the coal seam.

[0019] Four adjacent drainage boreholes in two rows that are distributed in a rectangular pattern constitute a borehole group. The number of borehole groups is equal to the number of blasting boreholes and they correspond one-to-one. Any blasting borehole is located at the center of the four drainage boreholes distributed in a rectangular pattern within the corresponding borehole group.

[0020] The section of the blasting borehole from the bottom to 1m above the top surface of the coal seam is filled with explosive charge.

[0021] The beneficial effects of this invention are:

[0022] After the extraction boreholes and blasting boreholes are punched, the diameter of the boreholes increases. The extraction boreholes can serve as free surfaces, while the blasting boreholes, when filled with water, can cause the coal seam floor to fracture and form a network of fractures that are difficult to close. At the same time, the coal body between various types of boreholes is displaced, thus loosening and increasing the permeability of the coal seam in this area.

[0023] Under the dynamic load of blasting, water can enter the finer pores and fissures of the coal body, preventing water from blocking the extraction channels. At the same time, it increases the water content of the coal body, which can significantly reduce dust during the later tunnel excavation process and improve the working environment at the tunnel face. The water left in the borehole by hydraulic measures can be turned from waste into treasure. The operation is simple and the permeability enhancement effect is significant. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1This is a side view schematic diagram of the arrangement of extraction boreholes and blasting boreholes of the present invention;

[0026] Figure 2 This is a schematic diagram of any hole group and blasting borehole of the present invention;

[0027] Figure 3 This is a schematic diagram of the coal seam fracture morphology after blasting, according to the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] like Figures 1 to 3 As shown, a method for suppressing coal seam outbursts by reverse blasting through downward cross-layer drilling in a tunnel includes the following steps:

[0030] Two rows of downward-facing extraction boreholes 1 are opened on the third bench of the coal seam facing the working face;

[0031] A row of blasting boreholes 2 with the same orientation is opened in the middle of the two rows of extraction boreholes 1, and the blasting boreholes 2 are all placed in the same axis as the extraction boreholes 1.

[0032] Hydraulic flushing was performed on each extraction borehole 1 and blasting borehole 2;

[0033] Connect extraction borehole 1 to the extraction pipeline for gas extraction.

[0034] Each blasting borehole 2 is filled with a blasting charge 5;

[0035] Water was injected into all blasting boreholes 2 until the liquid level was 5 cm above the explosive charge.

[0036] The blasting borehole 2 is sealed above the liquid surface, and the detonation line is led out of the blasting borehole 2 through the sealed part.

[0037] The explosive charge 5 in each blasting borehole 2 is detonated simultaneously, and the blasting borehole 2 after detonation is connected to the extraction pipeline for gas extraction.

[0038] After the extraction borehole 1 and blasting borehole 2 are hydraulically flushed, the borehole diameter increases. After the blasting borehole 2 is filled with explosive charge 5 and water is injected, the blasting action can cause the bottom plate 4 of the coal seam 3 to fracture and form a network of fractures that are difficult to close. At the same time, it can also cause the coal body between various boreholes to shift, thereby loosening and increasing the permeability of the coal seam 3 in this area. This can improve the permeability between coal and gas, which is conducive to the release of gas and the reduction of gas concentration, thereby reducing the probability of coal and gas outburst accidents.

[0039] Furthermore, under the dynamic load of blasting, moisture can enter the finer pores and fissures of the coal body, increasing the water content of the coal body. This can significantly reduce dust during the later tunnel excavation process and improve the working environment at the tunnel face.

[0040] The diameter of the extraction borehole 1 is 153 mm, and the bottom of the extraction borehole 1 is located at 2 / 3 of the thickness of the coal seam 3. The bottom of the extraction borehole 1 being located at 2 / 3 of the thickness of the coal seam 3 can effectively improve coal mining efficiency, reduce resource waste, ensure the stability of the mine structure, and provide convenience for subsequent operations.

[0041] The two rows of extraction boreholes 1 are placed symmetrically, with a spacing of 5m between them. The symmetrical placement of the two rows of extraction boreholes 1 allows for a more even distribution on the working face, which is beneficial for the uniform extraction of gas from the coal seam 3 and avoids excessively high gas concentrations or local accumulation.

[0042] The distance between two adjacent extraction boreholes 1 in each row is 5m.

[0043] The diameter of the blasting borehole 2 is 94mm. The blasting borehole 2 penetrates the coal seam 3 and extends 1m into the bottom plate 4 below the coal seam 3. The penetration of the blasting borehole 2 into the coal seam 3 can improve the structure of the coal seam 3, help reduce local stress concentration, improve the stability of the coal seam 3, and at the same time reduce the gas concentration in the coal seam 3, thereby reducing the risk of gas explosion.

[0044] Four adjacent drainage boreholes 1 arranged in a rectangular pattern in the two rows of drainage boreholes 1 constitute a borehole group. The number of borehole groups is equal to and corresponds one-to-one with the number of blasting boreholes 2. Each blasting borehole 2 is located at the center of the four rectangularly distributed drainage boreholes 1 in the corresponding borehole group. This ensures that the blasting charge 5 can cover the area around each drainage borehole 1 on the periphery, thereby improving the blasting breaking effect.

[0045] The section from the bottom of the blasting borehole 2 to 1m above the top surface of the coal seam 3 is filled with explosive charge 5; this can improve the blasting effect, crushing uniformity and coal seam 3 mining efficiency, and has a positive impact on the release of gas and reduction of coal dust generation in the coal seam 3.

[0046] The section of borehole 2 that is 1m above the top surface of coal seam 3 is the sealing section 6.

[0047] Preferably, the blasting borehole 2 is sealed using a capsule sealer; the capsule sealer works by inserting a capsule filled with sealing material into the borehole, and then using pressure or other means to make the sealing material inside the capsule expand and fill the borehole channel, thereby sealing and reinforcing the borehole.

[0048] The capsule sealer is a preferred method for sealing in this application, but materials such as potting compound or epoxy resin can also be used for sealing.

[0049] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0050] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A downward through-seam borehole reverse blasting outburst elimination method for tunneling outburst coal seams, characterized in that, The method comprises the following steps: Two rows of downward gas extraction boreholes (1) are arranged on the coal seam (3) step; A row of blasting boreholes (2) with the same arrangement direction is arranged at the middle position of the two rows of gas extraction boreholes (1), and the blasting boreholes (2) are coaxially arranged with the gas extraction boreholes (1); The gas extraction boreholes (1) and the blasting boreholes (2) are subjected to hydraulic punching, and the diameters of the gas extraction boreholes (1) and the blasting boreholes (2) are increased after being punched; The gas extraction boreholes (1) are connected with the gas extraction pipeline for gas extraction; The blasting boreholes (2) are filled with blasting columns (5); The blasting boreholes (2) are filled with water to a liquid level higher than the blasting columns (5); The blasting boreholes (2) are sealed, the sealing position is above the liquid level, and the detonation circuit is led out of the blasting borehole (2) through the sealing part; The blasting columns (5) in the blasting boreholes (2) are simultaneously detonated, and under the action of the blasting dynamic load, water can enter the relatively small coal body pore cracks to avoid water blockage of the extraction channel, and the blasting boreholes (2) connected with the gas extraction pipeline are used for gas extraction after detonation; Any adjacent four gas extraction boreholes (1) in the two rows of gas extraction boreholes (1) are arranged in a rectangular distribution to form a hole group, the number of the hole group is equal to that of the blasting boreholes (2) and one-to-one correspondence exists between the hole group and the blasting boreholes (2), and any blasting borehole (2) is located at the center position of the four gas extraction boreholes (1) arranged in a rectangular distribution in the corresponding hole group.

2. The reverse blasting outburst control method of downward through-seam drill hole for tunneling outburst seam according to claim 1, characterized in that, The diameter of the gas extraction borehole (1) is 153 mm, and the bottom of the gas extraction borehole (1) is located at the position of 2 / 3 of the thickness of the coal seam (3).

3. The reverse blasting outburst control method of downward through-seam drill hole for tunneling outburst seam according to claim 2, characterized in that, The two rows of gas extraction boreholes (1) are symmetrically arranged, and the distance between the two rows of gas extraction boreholes (1) is 5 m.

4. The reverse blasting outburst control method of downward through-seam drill hole for tunneling outburst seam according to claim 3, characterized in that, The distance between the two adjacent gas extraction boreholes (1) in each row of gas extraction boreholes (1) is 5 m.

5. The reverse blasting outburst control method of downward through-seam drill hole for tunneling outburst seam according to claim 4, characterized in that, The diameter of the blasting borehole (2) is 94 mm, the blasting borehole (2) penetrates the coal seam (3) and extends 1 m into the floor (4) below the coal seam (3).

6. The reverse blasting outburst control method of downward through-seam drill hole for tunneling outburst seam according to claim 5, characterized in that, The hole section of the blasting borehole (2) from the bottom to the position 1 m above the top surface of the coal seam (3) is filled with the blasting column (5).

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