CN108999596B - A method of supercritical CO2 point jet impingement gas explosion to fracturing coal and rock mass - Google Patents

Abstract

Supercritical CO₂A method for cracking coal and rock mass by point-type jet impact gas explosion belongs to the technical field of permeation enhancement of low-permeability gas coal seams in coal mines and the field of blasting engineering. The method comprises the steps of drilling holes in a coal rock body to serve as blasting holes and auxiliary holes; mixing liquid CO₂Pushing the fracturing device to the bottom of the blast hole, and detecting the detonation circuit to ensure the connection of the detonation circuit; injecting a foam hole sealing agent/quick setting expanding agent to segment the blast hole, and grouting the segments at intervals, wherein the grouting amount is estimated according to each interval volume; initiation of liquid CO₂And the fracturing device is used for detecting the fracturing effect and recovering the fracturing device after the blasting is finished. The method utilizes supercritical CO to the maximum extent₂The limited explosion energy of the gas explosion is concentrated into one point or plane to be used for fracturing the coal rock mass, so that the effective fracturing range is enlarged or the breaking rate of the coal rock mass is improved, the effect is more obvious, the operation is easy, and the cost is low.

Description

A method of supercritical CO2 point jet impingement gas explosion to fracturing coal and rock mass

technical field

The invention relates to the technical field of permeation enhancement of low-permeability gas coal seams in coal mines and the field of blasting engineering, in particular to a method for fracturing coal and rock mass by supercritical CO ₂ point-type jet impingement gas explosion.

Background technique

The supercritical CO ₂ gas explosion and fracturing technology originated from the Cardox technology invented by American engineers in 1914. It is a non-explosive physical blasting technology that uses the high-pressure gas generated by the heating and expansion of liquid CO ₂ to rupture coal seams and rock formations. Compared with hydraulic fracturing and chemical explosive blasting, the maximum peak pressure generated by supercritical CO ₂ gas explosion is between the maximum peak pressure generated by hydraulic fracturing and chemical explosive blasting, which can avoid the pressure around the blasting hole due to excessively high pressure. The coal and rock mass produces a crushing zone and consumes most of the limited blasting energy, and it can also avoid the failure to achieve the expected fracturing effect due to too low pressure. In addition, chemical explosive blasting is a high-frequency dynamic load, and the entire boosting and depressurizing process is at the microsecond level, while supercritical CO ₂ gas explosion is a medium-frequency dynamic load, and the high-pressure blasting energy can last for hundreds of milliseconds. The time and medium frequency dynamic load is more conducive to fracturing coal rock mass. In addition, hydraulic fracturing is a static load, and the action time is longer _than that of supercritical _CO2 gas explosion, which can be repeatedly used to fracture coal rock mass in a short time. Hydraulic fracturing is significantly affected by in-situ stress, which limits its engineering application scope, while supercritical CO ₂ gas explosion is not significantly affected by in-situ stress, and gas explosion can form several cracks around the blasting hole along its radial direction. In addition, the hydraulic fracturing equipment is complex, the input cost is high, and it will pollute the formation or groundwater, while the supercritical CO ₂ gas explosion has low single input cost, the fracturing device can be reused thousands of times, the structure is simple and easy to operate, and it is environmentally friendly. No pollution. In recent years, the supercritical CO ₂ gas explosion fracturing technology has received extensive attention, especially in the field of mining engineering, whether it is artificial infiltration of low-permeability gas coal seams or coal and rock mass blasting, all of which have won the favor of on-site staff. .

Supercritical CO ₂ gas explosion mainly fractures coal and rock mass through shock fracturing and gas wedge fracturing of high-pressure explosion-generated supercritical CO ₂ gas. The effects of shock fracturing and gas wedge fracturing are not only consistent with liquid CO ₂ The blast energy released by the cracker is also significantly affected by the gap between the cracker and the blast hole. The larger the gap between the cracker and the blasting hole, the more unfavorable it is to concentrate the limited blasting energy released by the cracker for fracturing the coal and rock mass, resulting in poor fracturing effect or unsatisfactory rock blasting effect. .

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the existing supercritical CO ₂ gas explosion and fracturing technology, and to provide a method for cracking coal rock mass caused by supercritical CO ₂ point-type jet impingement gas explosion, which is suitable for cracking and increasing permeability and low Infiltrate gas coal seam or blast coal rock mass. The method can utilize the limited blasting energy of supercritical _CO2 gas explosion to the greatest extent, increase the effective fracturing range or improve the crushing rate of coal and rock mass, and has low cost, simple and easy operation.

The technical scheme of the present invention is a method for cracking coal rock mass caused by supercritical _CO2 point jet impact gas explosion, comprising the following steps:

Step 1: Make the blast hole

Applying a plurality of boreholes in the coal rock mass, the boreholes include blast holes and auxiliary holes;

Step 2: Place the liquid _CO2 cracker and grouting pipe in the blast hole

Push the liquid CO ₂ cracker into the blasting hole. When pushing, one end of the energy release valve of the liquid CO ₂ cracker faces the bottom of the blasting hole. After pushing, the detonation circuit is detected and ensured that it is connected;

Extend the nozzle of the grouting pipe into the outer wall of the first liquid CO ₂ cracker energy storage pipe from the bottom of the blasting hole;

Step 3: Set the pre-grouting interval

In the gap between the liquid _CO2 cracker and the blasting hole, through the grouting pipe, along the axis of the blasting hole, from the bottom of the blasting hole to the blasting hole orifice, to each liquid _CO2 cracker energy storage tube in turn At the screw joints at both ends, inject foam sealing agent or quick-setting expansion agent, and then form an axial pre-grouting interval between the foam sealing agent or rapid-setting expansion agent at both ends of the liquid CO ₂ cracker;

Step 4: Setting up the CO ₂ -point jet impinging on the gas explosion area

After the foam sealing agent or quick-setting expansion agent at the screw joints of the two ends of the energy storage tube of the liquid CO ₂ cracker is completely solidified, pass the grouting pipe from the bottom of the blasting hole to the orifice of the blasting hole, and then to the pre-grouting interval. Inject the fast-setting expansion slurry into the middle of the blasting hole, so that the first foam sealing agent or the gap between the fast-setting expansion agent and the bottom of the blasting hole is formed at the bottom of the blasting hole, which is the CO ₂ point jet impact gas explosion area;

Step 5: Blasting Hole Orifice Sealing and Initiating Rupturer

(1) Fix the first liquid CO ₂ cracker from the orifice of the blasting hole and grouting and seal the orifice of the blasting hole;

(2) After the rapid-setting expansion slurry is completely solidified, the blasting site personnel are evacuated to the outside of the blasting warning line, and the liquid CO ₂ crackers are detonated one by one or at the same time through the detonators; after the blasting, the cracking effect and Recovery of liquid _CO2 cracker.

In the step 1, the blasting hole is applied as one or more of horizontal, vertical or inclined according to the specific actual project and the conditions of the coal and rock mass.

In the step 1, when the coal rock mass is soft coal rock mass, a screen pipe is lowered into each borehole to prevent the hole from collapsing.

In the above-mentioned step 1, when it is a permeable coal rock mass, the distance from the set blasting hole to its surrounding air surface > the coal rock mass blasting minimum resistance line;

When blasting the coal and rock mass, the shortest distance from the blasting hole to the free surface < the minimum resistance line of the coal and rock mass blasting.

In the step 1, the auxiliary holes are one or more of observation holes, extraction holes or control holes; the auxiliary holes are arranged in parallel or non-parallel around the blasting holes, and the setting range is at least Covers the effective cracking range of gas explosion.

In the above-mentioned step 2, when a plurality of liquid CO ₂ crackers are arranged in a blasting hole, the subsequent liquid CO ₂ crackers are connected in series with the liquid CO ₂ crackers in the blasting hole end to end, and then the series will be well connected. Push the liquid _CO2 cracker into the blasting hole, check the detonation circuit again after pushing and make sure it is connected; repeat the above steps until all the liquid _CO2 cracking device is pushed into the blasting hole;

In the above-mentioned step 2, in the case of permeation-increasing coal and rock mass, the liquid CO ₂ cracker is fully buried; in the case of blasting coal and rock mass, the liquid CO ₂ cracker is fully buried or half-buried.

In the step 3, the screw joints at both ends are the screw joint of the energy storage tube and the energy discharge valve, and the screw joint of the energy storage tube and the filling valve.

In the step 3, the length of each pre-grouting interval is less than or equal to the length of each liquid CO ₂ cracker energy storage tube.

In the step 3, the foam sealing agent or the quick-setting expansion agent has anaerobic properties.

In the above-mentioned step 4, when a plurality of liquid CO ₂ crackers are arranged in one blasting hole, the gaps between adjacent grouting intervals also form the CO ₂ point jet impacting the gas explosion area.

In the step 4, the injection amount of the quick-setting and expanding slurry is estimated according to the volume of the pre-grouting interval.

In the described step 5(1), when the liquid _CO2 cracker is fixed and the blasting hole orifice is grouted and sealed, according to the setting of the liquid _CO2 cracker, it is divided into fully buried or half buried;

Case 1: When the liquid CO ₂ cracker is set in a fully buried way, different methods are used to fix the liquid CO ₂ cracker and seal the blast hole orifice according to the conditions at the orifice of the blasting hole. The methods are as follows: :

The first one: directly grouting and sealing the orifice section without liquid CO ₂ cracker at the orifice of the blasting hole;

The second type: put one end of a metal rod against the filling valve of the liquid _CO2 cracker at the outermost side of the blasting hole, and the other end of the metal rod is set outside the blasting hole orifice and fixed to prevent the liquid _CO2 cracker from being thrown out and blasting After that, the gap between the blast hole orifice and the metal rod is grouted and sealed;

The third type: Before pushing the liquid CO ₂ cracker to the blasting hole, tie the chain to the filling valve of the liquid CO ₂ cracker, and anchor the chain in the stable coal rock body outside the blasting affected area. Prevent the liquid CO ₂ cracker from flying away, and then grouting and sealing the blast hole orifice;

Case 2: When the liquid CO ₂ cracker is set in a semi-buried manner, the chain is tied to the filling valve of the semi-buried liquid CO ₂ cracker, and the chain is anchored to the stable coal and rock mass outside the blasting affected area Inside, to prevent the liquid _CO2 cracker from flying away, and then grouting the blast hole orifice to seal the hole.

In the above case 1, when it is a permeable coal rock mass, the length of the orifice section without the liquid CO ₂ cracker at the blasting hole is greater than the minimum resistance line of the coal rock mass blasting;

In the above case 1, when it is a permeable coal rock mass, the method of sealing and grouting in the orifice section without the liquid _CO2 cracker at the blasting hole is the first or second method; when it is a blasting coal rock mass When there is no liquid _CO2 cracker at the blasting hole, the method of sealing and grouting is the third method.

A method of supercritical CO ₂ point-type jet impinging gas explosion to crack coal and rock mass of the present invention has the following beneficial effects:

The above technical solution solves the defects of the existing supercritical _CO2 gas explosion and fracturing technology, realizes the supercritical _CO2 point jet impingement gas explosion to fracture the coal rock mass, and utilizes the limited supercritical _CO2 gas explosion to the greatest extent. Concentrating energy on a "point" or "surface" for fracturing coal and rock mass can significantly improve the blasting range and rock-breaking effect, expand the effective fracturing range, and improve the effect of increasing permeability. It is easy to operate and has low cost.

Description of drawings

Fig. 1 is the overall structure schematic diagram of supercritical CO ₂ point type jet impingement gas explosion in the embodiment 1 of the present invention to cause cracking and seepage-increasing coal body;

Fig. 2 is a partial enlarged view of blasting hole 6 in Fig. 1;

3 is a schematic diagram of the overall structure of the open-pit coal seam cracked by supercritical CO ₂ point jet impingement gas explosion in Example 2 of the present invention;

Fig. 4 is A-A sectional view in Fig. 3;

Fig. 5 is the enlarged view of blasting hole 6 in Fig. 3; Wherein, (a) is half buried, (b) is fully buried;

6 is a schematic diagram of the overall structure of the residual top coal cracked by supercritical CO ₂ point jet impingement gas explosion in Example 3 of the present invention;

Fig. 7 is the left elevation view in Fig. 6;

Figure 8 is an enlarged view of the blasting hole 6 in Figure 6;

In the picture:

1-goaf, 2-coal seam, 3-air return road, 4-air inlet road, 5-working face, 6-blasting hole, 7-control hole/drainage hole/observation hole, 8-liquid _CO2 Cracker, 9- Energy release valve, 10- Filling valve, 11- Energy storage tube, 12- Foam sealing agent or quick-setting expansion agent, 13- Grouting pipe, 14- Quick-setting expansion slurry, 15- Lead wire, 16-detonator, 17-air face, 18-chain, 19-anchor, 20-coal seam floor, 21-coal seam roof, 22-residual top coal, S-CO ₂ -point jet impact gas explosion area, D- Pre-grouting interval, D'-grouting interval, L-the shortest distance from the outermost blasting hole to the free surface.

Detailed ways

Below in conjunction with the accompanying drawings and specific embodiments, the technical solutions of the present invention are described in detail:

Example 1

A method for fracturing coal and rock mass by supercritical CO ₂ point jet impingement gas explosion, the present embodiment is a method for increasing permeability of coal mass, and its specific implementation is shown in Figure 1 and Figure 2:

Step 1. From the air inlet road (4) and the return air road (3) to the coal seam (2), make the working face (5) half-length and staggered drill holes as blasting holes (6), observation For the hole/drainage hole/control hole (7), the distance from the blasting hole (6) to the working face (5) is greater than the minimum resistance line of coal blasting;

Step 2. The liquid _CO2 cracker (8) used is provided with an energy release valve (9) at one end and a filling valve (10) at the other end, between the energy release valve (9) and the filling valve (10). The tube body is an energy storage tube (11), and the liquid _CO cracker (8) is provided with a detonation circuit wire (15) connected to the detonator (16);

Push the liquid _CO2 cracker (8) into the blasting hole (6), and one end of the energy discharge valve (9) of the liquid _CO2 cracker (8) faces the bottom of the blasting hole (6) when pushing, and check after pushing Detonate the circuit and ensure that it is connected; connect the subsequent liquid _CO2 cracker (8) with the liquid CO2 cracker (8) in the blasting hole ( ₆ ) end to end, and then connect the serially connected liquid _CO2 cracker (8). (8) Push into the blasting hole (6), check the detonation circuit again after pushing and ensure that it is connected; repeat the above steps until all the liquid _CO2 crackers (8) are pushed into the blasting hole (6), and the liquid _CO2 The cracking device (8) is fully buried;

Extend the nozzle of the grouting pipe (13) to the periphery of the outer wall of the first liquid _CO2 cracker (8) energy storage pipe (11) from the bottom of the blasting hole (6);

Step 3. In the gap between the liquid CO ₂ cracker (8) and the blasting hole (6), through the grouting pipe (13), along the axis of the blasting hole (6), from the bottom of the blasting hole (6) Go to the orifice of the blasting hole (6), and then to each liquid CO ₂ cracker (8), the storage tube (11) and the discharge valve (9), and the liquid _CO cracker (8) The storage tube is screwed (11) is screwed with the filling valve (10), and a foam sealing agent (12) is injected to form an axial section between the foam sealing agent (12) at both ends of the liquid _CO cracker (8). Pre-grouting interval (D), and finally the entire blasting hole (6) forms a multi-section axial pre-grouting interval (D);

Step 4. After the foam sealant (12) at the screw joints of the two ends of the liquid _CO2 cracker (8) energy storage tube (11) is completely solidified, pass through the grouting tube (13), from the blasting hole (6) The bottom of the blasting hole (6) is injected into the pre-grouting interval (D) in turn with the quick-setting and expanding slurry (14), and then the first foam sealing agent (12) is placed at the bottom of the blasting hole (6). The gap between the bottom of the hole and the blasting hole (6), and the gap between the adjacent grouting intervals (D'), both form the CO ₂ point jet impingement gas explosion area (S);

The injection amount of the fast-setting and expanding slurry (14) is estimated according to the volume of each pre-grouting interval (D); after the grouting is completed, the grouting pipe (13) is pulled out from the blasting hole (6);

Step 5. Repeat Step 2, Step 3 and Step 4, and perform segmented grouting on the remaining blasting holes (6) to form the liquid _CO cracker (8) the energy storage tube (11) the whole body long grouting and sealing part. Interval CO ₂ -point jet impinges on the gas explosion area (S);

Step 6. The outermost length of all blasting holes (6) is greater than the minimum resistance line of coal blasting and there is no liquid CO ₂ cracker (8), directly grouting and sealing; ) is completely solidified, the blasting site personnel are evacuated to the outside of the blasting warning line; then the liquid _CO2 cracker (8) is detonated slightly or simultaneously through the detonator (16); after the blasting, the cracking effect is detected and the liquid CO2 is recovered. ₂ Cracker (8).

Example 2

A method for fracturing coal and rock mass by supercritical CO ₂ point jet impact gas explosion, the present embodiment is a method for blasting open-pit coal seam, and its specific implementation is shown in Figure 3, Figure 4 and Figure 5(b):

Step 1. On the steps of the open-pit coal seam (2), drill vertical holes row by row as blasting holes (6). (2) The shortest distance (L) from the outermost blasting hole (6) of the step to its surrounding empty surface (17) is less than the minimum resistance line of coal blasting;

Step 2. Use chains (18) to bind with the filling valve (10) of the liquid CO ₂ cracker (8), and anchor the chains (18) in the stable coal rock body outside the blasting influence area through anchors (19). , to prevent the liquid CO ₂ cracker (8) from being thrown away, and then push the liquid CO ₂ cracker (8) to the bottom of the blasting hole (6), and the end of the energy release valve (9) faces the bottom of the hole when pushing, Then, in the gap between the liquid CO ₂ cracker (8) and the blasting hole (6), through the grouting pipe (13), the liquid CO ₂ cracker (8), the energy storage pipe (11) and the energy discharge valve ( 9) The foam sealing agent (12) is injected into the screw joint, so that the gap between the orifice of the blasting hole (6) and the foam sealing agent (12) is the pre-grouting interval (D) of the blasting hole (6), After that, the detonation circuit is detected and ensured that it is connected, and the liquid _CO2 cracker (8) is fully buried;

Step 3: inject the quick-setting and expanding slurry (14) into the pre-grouting interval (D) of the blasting hole through the grouting pipe (13), and the injection amount is estimated according to the volume of the pre-grouting interval (D); thus the blasting hole is (6) The gap between the first foam sealant (12) and the bottom of the blasting hole (6) from the bottom of the hole is the CO ₂ point jet impinging gas explosion area (S). After the grouting is completed, the grouting pipe (13) of the sealing slurry is pulled out from the blasting hole (6);

Step 4. Repeat steps 2 and 3, and grouting and sealing the remaining blasting holes (6);

Step 5. After the rapid-setting expansion slurry (14) is completely solidified, the blasting site personnel are evacuated to the outside of the blasting warning line, and the liquid CO is detonated step by step through the detonator (16) according to the step of the open coal seam (2) from low to high. _2. The crackers (8), and the liquid _CO2 crackers (8) on the same step, are detonated row by row in order from near to far to the inside of the step according to the distance from the empty surface (17), and after the blasting is completed The liquid _CO2 cracker (8) is recovered.

Example 3

A method for fracturing coal and rock mass by supercritical CO ₂ point jet impact gas explosion, the present embodiment is a method for blasting residual top coal, and its specific implementation is shown in Figure 6, Figure 7, and Figure 8:

The residual top coal is blasted by using the supercritical CO ₂ point jet impingement gas blasting method to crack the coal body.

Wherein, step 1 is as follows: in the residual top coal (22), inclining boreholes are sequentially performed row by row as blasting holes (6), and the hole depth and row spacing are respectively based on the thickness of the residual top coal (22), the length of the overhang and the The physical and mechanical properties of the coal body are set, and the shortest distance from the outermost blasting hole (6) to its surrounding empty surface (17) is less than the minimum resistance line of the coal body blasting;

Step 5 is: after the rapid-setting expansion slurry (14) is completely solidified, the blasting site personnel are evacuated to the outside of the blasting warning line, and the liquid CO ₂ cracker (8) is detonated by the detonator (16), and the blasting device is in the air according to the distance. The distance of the surface (17) is from near to far to the interior of the residual top coal (22) row by row and row by row, and the liquid CO ₂ cracker (8) is recovered after the blasting is completed.

Example 4

A method of supercritical CO ₂ point-type jet impingement gas blasting and fracturing coal and rock mass, the present embodiment is a method for blasting open-pit coal seams, and its specific implementation is the same as that of embodiment 2, and the difference is:

Step 2, the setting method of the liquid _CO2 cracker (8) is shown in Figure 5(a), the liquid _CO2 cracker (8) is semi-buried, and it adopts the chain (18) and the liquid _CO2 cracker (8) The filling valve (10) is bundled, and the chain (18) is anchored in the stable coal rock body outside the blasting influence area through the anchoring device (19) to prevent the liquid _CO2 cracker from being thrown away.

Example 5

A method of supercritical CO ₂ point type jet impingement gas explosion to fracturing coal and rock mass, the present embodiment is a method for increasing permeability of coal mass, and its specific implementation is the same as that of embodiment 1, the difference is:

The foam sealing agent in Example 1 was replaced with a quick-setting expansion agent.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited to this, and any changes or substitutions that are not thought of through creative work should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined by the claims.

Claims (10)

1. a method for supercritical CO ₂ point type jet impact gas explosion to cause fracturing coal rock mass, is characterized in that, comprises the following steps: Step 1: Make the blast hole Applying a plurality of boreholes in the coal rock mass, the boreholes include blast holes and auxiliary holes; Step 2: Place the liquid _CO2 cracker and grouting pipe in the blast hole Push the liquid CO ₂ cracker into the blasting hole. When pushing, one end of the energy release valve of the liquid CO ₂ cracker faces the bottom of the blasting hole. After pushing, the detonation circuit is detected and ensured that it is connected; Extend the nozzle of the grouting pipe into the outer wall of the first liquid CO ₂ cracker energy storage pipe from the bottom of the blasting hole; Step 3: Set the pre-grouting interval In the gap between the liquid _CO2 cracker and the blasting hole, through the grouting pipe, along the axis of the blasting hole, from the bottom of the blasting hole to the blasting hole orifice, to each liquid _CO2 cracker energy storage tube in turn At the screw joints at both ends, inject foam sealing agent or quick-setting expansion agent, and then form an axial pre-grouting interval between the foam sealing agent or rapid-setting expansion agent at both ends of the liquid CO ₂ cracker; Step 4: Setting up the supercritical CO ₂ -point jet impinging on the gas explosion area After the foam sealing agent or quick-setting expansion agent at the screw joints of the two ends of the energy storage tube of the liquid CO ₂ cracker is completely solidified, pass the grouting pipe from the bottom of the blasting hole to the orifice of the blasting hole, and then to the pre-grouting interval. The rapid-setting expansion slurry is injected into the middle of the blasting hole, so that the first foam sealing agent or the gap between the rapid-setting expansion agent and the bottom of the blasting hole is formed at the bottom of the blasting hole, which is the supercritical CO ₂ point jet impact gas explosion area; Step 5: Blasting Hole Orifice Sealing and Initiating Rupturer (1) Fix the first liquid CO ₂ cracker from the orifice of the blasting hole and grouting and seal the orifice of the blasting hole; (2) After the rapid-setting expansion slurry is completely solidified, the blasting site personnel are evacuated to the outside of the blasting warning line, and the liquid CO ₂ crackers are detonated one by one or at the same time through the detonators; after the blasting, the cracking effect and Recovery of liquid _CO2 cracker. 2. supercritical CO as claimed in claim 1 ₂ point type jet impingement gas explosion method for fracturing coal rock mass, is characterized in that, in described step 1, described blasting hole is according to concrete actual project and its coal The condition of the rock mass, applied as one or more of horizontal, vertical or inclined; In the step 1, the auxiliary holes are one or more of observation holes, extraction holes or control holes; the auxiliary holes are arranged in parallel or non-parallel around the blasting holes, and the setting range is at least Covering the effective cracking range of gas explosion; In the step 1, when the coal rock mass is a soft coal rock mass, a screen pipe is lowered into each borehole. 3. The method for supercritical CO ₂ point jet impingement gas blasting and fracturing coal rock mass as claimed in claim 1, wherein in the described step 1, when it is the permeation-increasing coal rock mass, the blasting set The distance from the hole to its surrounding air surface > the minimum resistance line of coal and rock mass blasting; When blasting the coal and rock mass, the shortest distance from the blasting hole to the free surface < the minimum resistance line of the coal and rock mass blasting. 4. The method of supercritical CO ₂ point-type jet impingement gas blasting and fracturing coal rock mass as claimed in claim 1, characterized in that, in the step 2, when a plurality of liquid CO ₂ blast holes are arranged in a blasting hole When cracking, connect the subsequent liquid _CO2 cracker with the liquid _CO2 cracker in the blasting hole end to end, then push the serially connected liquid _CO2 cracker into the blasting hole, and check the detonation circuit again after pushing And make sure it's connected; repeat the above steps until all the liquid _CO2 cracker is pushed into the blast hole. 5. The method for supercritical CO ₂ point-type jet impingement gas blasting and fracturing coal rock mass according to claim 1, wherein in the step 2, when it is a permeation-increasing coal rock mass, liquid CO ₂ The cracker is fully buried; when it is used to blast coal and rock mass, the liquid _CO2 cracker is fully buried or half-buried. 6. The method for supercritical CO ₂ point-type jet impingement gas explosion fracturing coal rock mass according to claim 1, wherein in the step 3, the length of each pre-grouting interval is ≤ The length of each liquid _CO2 cracker energy storage tube; In the step 3, the foam sealing agent or the quick-setting expansion agent has anaerobic properties. 7. The method for supercritical CO ₂ point type jet impingement gas blasting and fracturing coal rock mass as claimed in claim 1 or 4, characterized in that, in the step 4, when a plurality of liquid COs are arranged in a blasting hole ₂ crackers, the gap between adjacent grouting intervals also forms the supercritical CO ₂ point jet impinging gas explosion area. 8. The method for supercritical CO ₂ point jet impingement gas explosion cracking coal and rock mass as claimed in claim 1, characterized in that, in the step 4, the injection amount of the fast-setting and expanding slurry is pre-determined. Volume estimation of grouting intervals. 9. The method for supercritical CO ₂ point jet impingement gas explosion to crack coal rock mass as claimed in claim 1, characterized in that, in the described step 5(1), the liquid CO ₂ cracker is fixed When grouting and sealing of the orifice of the blasting hole, according to the setting of the liquid CO ₂ cracker, it can be divided into fully buried or half buried; Case 1: When the liquid CO ₂ cracker is set in a fully buried way, different methods are used to fix the liquid CO ₂ cracker and seal the blast hole orifice according to the conditions at the orifice of the blasting hole. The methods are as follows: : The first one: directly grouting and sealing the orifice section without liquid CO ₂ cracker at the orifice of the blasting hole; The second type: put one end of a metal rod against the filling valve of the liquid _CO2 cracker at the outermost side of the blasting hole, and the other end of the metal rod is set outside the blasting hole orifice and fixed to prevent the liquid _CO2 cracker from being thrown out and blasting After that, the gap between the blast hole orifice and the metal rod is grouted and sealed; The third type: Before pushing the liquid CO ₂ cracker to the blasting hole, tie the chain to the filling valve of the liquid CO ₂ cracker, and anchor the chain in the stable coal rock body outside the blasting affected area. Prevent the liquid CO ₂ cracker from flying away, and then grouting and sealing the blast hole orifice; Case 2: When the liquid CO ₂ cracker is set in a semi-buried manner, the chain is tied to the filling valve of the semi-buried liquid CO ₂ cracker, and the chain is anchored to the stable coal and rock mass outside the blasting affected area Inside, to prevent the liquid CO ₂ cracker from flying away, and then grouting and sealing the blast hole orifice. 10. The method for cracking coal rock mass by supercritical CO ₂ point jet impingement gas explosion according to claim 9, characterized in that, in the first case, when it is a permeation-increasing coal rock mass, the said The length of the orifice section without the liquid CO ₂ cracker at the blasting hole > the minimum resistance line of coal and rock mass blasting; In the first case, when it is a permeation-enhancing coal rock mass, the method of sealing and grouting in the orifice section of the blasting hole without the liquid _CO2 cracker is the first or second; In the case of rock mass, the method of sealing and grouting in the orifice section of the cracker without liquid _CO2 at the blasting hole is the third method.

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