Method for increasing permeability of low-permeability coal seam by means of deep-hole directional pre-splitting blasting

[0019] The method for increasing permeability of low-permeability coal seam by deep hole directional pre-splitting blasting of the present invention, its preferred embodiment is:

[0020] Include steps:

[0021] First of all, using conventional operation methods, construct large-diameter blasting holes in high-gas and low-permeability coal seams;

[0022] Then, the four-way vertical slit pipe is used as the blasting charge pipe and the water bag pipe, and the four positions of 0°, 90°, 180° and 270° in the circumferential direction of the four-way vertical slit pipe are respectively provided with longitudinal slits. seam

[0023] Afterwards, the four-way vertical slotted tube with the charge roll and the four-way vertical slotted tube with the water bag are arranged at intervals to fill the large-diameter blasting hole with explosives, and the explosives are indexed through the double detonator. , to complete the blasting and anti-reflection operation on low-permeable thick coal seams.

[0024] The slits of the four-way vertically slit pipe and the slits of the adjacent four-way vertically slit pipes are longitudinally aligned with each other.

[0025] The method of loading explosives into the blasting hole is radial non-coupling charge, and the coefficient of radial non-coupling charge is 1.6-2.1.

[0026] The diameter of the blasting blast hole is 60-80mm. A plurality of four-way vertical slit pipes are connected to each other and pushed into the blast hole, and yellow mud rolls are filled at the blast hole to block the blast hole.

[0027] The four-way vertically slit pipes are connected to each other in a threaded socket, and the detonating cord is bound to the cross beam at the bottom end of the first four-way vertically slit pipe at the bottom of the blast hole.

[0028] The outer diameter of the four-way vertical slit pipe is 48mm, the wall thickness is 4mm, the inner diameter is 40mm, and the length is 1500mm, and its two ends are respectively 100mm long inner thread and outer thread that match each other.

[0029] The size of each slit on the four-way vertical slit pipe is length×width=250mm×4mm, and the interval between two adjacent slits in the axial direction is 50mm.

[0030] The method for increasing permeability of low-permeable coal seams by deep-hole directional pre-splitting blasting of the present invention can form interpenetrating fissure networks after coal seam blasting, improve the gas permeability of low-permeability and high-gas coal seams, so as to ensure the effect of gas drainage and obtain better results. High gas drainage efficiency, while preventing the occurrence of gas disasters to a certain extent.

[0031] Design idea of ​​the present invention is:

[0032] By analyzing the characteristics of coal structure and pores, it is concluded that the huge network formed by pores and fissures is the gas migration channel, and the amount of gas migration is related to the coal seam permeability and the mechanical properties of coal failure. By analyzing the action mechanism of deep hole pre-splitting blasting technology on low-permeability and high-gas coal seam, it is concluded that after explosive explosion, the action of detonation stress wave and detonation gas is the main factor for the formation of a large number of cracks in the coal medium. The dynamic fracture mechanism on which the blasting process is based is: under the action of the blast stress wave, radial cracks first appear around the blast hole, resulting in a large number of cracks; Expansion, thereby forming a radial fracture zone around the borehole. In order to make the energy of the stress wave mainly act on the broken coal body, a connected fracture network centered on the blast hole is formed in the coal body. For this reason, the present invention proposes a new idea of ​​blasting using four-way vertically slotted pipes. The slit tube blasting has the effect of gathering energy, and the explosion energy of the explosive will be released preferentially at the slit, breaking the coal body in the direction of the slit, causing more cracks to be formed in the coal body in the direction of the prefabricated slit, and expanding the range of cracks in this direction , setting four-way slits on the charge tube greatly increases the scope of the connected fracture network formed by the coal body around the blast hole. At the same time, in order to further increase the crushing range of the coal body, an interpenetrating fracture network is formed in the coal body to prolong the action time of the explosive gas on the broken coal body. For this reason, the present invention proposes the new method that adopts four-way vertical slit pipe and medicine roll and four-way vertical slit pipe and water bag to charge medicine at intervals. Since water still exhibits strong incompressibility under high temperature and high pressure, and is a green and pollution-free fluid that can transmit pressure well, the water bag is rapidly compressed and ruptured under the high pressure of the explosion shock wave, forming Water jets "cut" the coal, and hydraulic fracturing creates cracks in the coal. Subsequently, the water moves along the opened coal fissures around the blast hole under the push of the detonation gas, and the detonation gas and water form a coupling effect, which jointly forms a "sharp action" on the coal fissures, wedged into the coal fissures , making the fissures further expand, prolonging the action time of the explosive gas on the coal fissures, and then forming a radial wave-shaped fissure zone around the borehole. At the same time, the "water mist" produced by the water jet can also effectively suppress or eliminate the sparks generated by the explosion, reducing the risk of coal seam gas explosion.

[0033] Action principle of the present invention is:

[0034] First, in order to increase the gas permeability of the deep coal seam, the gas in the coal seam is changed from the adsorption state to the free state, and the effect of pumping and discharging the gas in the coal seam is improved. Conventional operation methods can be used to construct deep pre-splitting blast holes in low-permeable coal seams. The diameter of the blast hole is generally 60-80mm, and the depth is generally 50-70m, depending on the thickness of the coal seam and the depth of gas drainage.

[0035] Due to the energy-gathering effect of the slit tube, the blasting energy is preferentially released along the slit direction, and stress concentration is generated in the slit direction, so that the fracture is preferentially generated along the slit direction. Therefore, four-way vertical slits are set on the charge tube. The size of the slits is 250mm×4mm (length×width), and the vertical distance between two adjacent slits is 50mm. In order to increase the ventilation effect of the coal body and ensure the formation of a uniformly connected fracture network in all directions of the coal body, the longitudinal slits in the circumferential direction should be staggered by 62.5 mm. At the same time, in order to increase the rigidity and stability of the slit tube and ensure that the slit tube will not be unstable and twisted during charging, the four-way vertical slit tube can be controlled between 1.5m and 2.5m.

[0036] In order to facilitate the filling and connection of explosives, 100mm-long matching inner and outer threads are respectively provided at both ends of the four-way vertically slit pipe. The slit pipes are connected in a threaded socket at intervals in sequence, and then slowly pushed into the blast hole. Wherein, at the end of the first slit tube at the bottom of the blasthole, two cross beams should be arranged to facilitate fixing the detonating cords, and the two detonating cords extend directly out of the blasthole along the inner wall of the charge tube.

[0037]Usually, the gun hole is filled with a special drug roll and water bag, wherein the drug roll is a cylindrical drug bag with a diameter of 38mm and a length of 1000mm, and the diameter and length of the water bag are the same as the drug roll.

[0038] Finally, the blast hole is loaded with explosives. Use yellow mud rolls to block the blast hole within a certain distance from the hole. Double detonating cords are used to detonate all blastholes at the same time to complete the deep hole directional pre-splitting blasting construction.

[0039] Normally, yellow mud rolls are used to block the hole within 10m, and double detonating cords are used to initiate explosives to improve the reliability of blasting. When blasting occurs in the blast hole, the energy gathering effect is formed in the direction of the kerf, and the coal body preferentially expands out of the crack surface along the kerf, forming a relatively long fracture zone. The strong pressure compresses and ruptures rapidly, forming a water jet to "cut" the surrounding coal body, further expanding the range of the fractured zone. Subsequently, the water is quickly wedged into the coal fractures under the impetus of the explosive gas, and the explosive gas and water form a "coupling effect" to form a "sharp action" on the coal fractures, which further expands the coal fractures and Radial wavy fissure zones are formed around the blast holes, and finally a network of interconnected fissures is formed in the coal body.

[0040] The present invention adopts the four-direction vertical slit tube equipped with drug rolls and the four-direction vertical slit tube equipped with water bags to charge medicine at intervals, and combines water cutting and slit tube blasting technology, and is specifically applied to low-permeability coal seam pre-treatment. Crack blasting anti-reflection work is under construction. Among them, the four-way vertical slit pipe is convenient to connect and easy to operate; the drug roll and water bag interval charging method is easy to operate and has a wide range of applications. At the same time, four-way vertical slotted pipe blasting can greatly increase the range of coal fissures, which is conducive to the formation of larger fissure zones around blastholes; The combination of energy such as the jet flow and the coupling effect of explosive gas and water acts on the coal body, which greatly improves the utilization rate of explosive explosion energy, greatly increases the range of cracks in the coal body, and forms an interconnected fracture network in the coal body. . At the same time, the "water mist" produced by the water jet can also effectively suppress or eliminate the sparks generated by the explosion, reducing the risk of coal seam gas explosion. This method greatly increases the air permeability of the low-permeability coal seam, improves the effect of gas pumping and discharge, and at the same time prevents the occurrence of gas disasters to a certain extent, ensuring the safe production of the mine.

Specific examples:

[0041] A method for increasing permeability of low-permeable coal seams in deep-hole directional pre-splitting blasting combined with the four-way vertically slit pipe 2 and the drug roll 4 and the four-way vertically slit pipe 2 and the water bag 5 for charge at intervals.

[0042] like figure 1 , figure 2 As shown, taking 3 blastholes as an example, the specific steps include:

[0043] Step 1: Construct large-diameter deep blast holes in the coal seam by adopting conventional operation methods.

[0044] Under normal circumstances, the coal seam is thick and has low air permeability, so the gas exists in the coal seam in the state of adsorption. The construction of deep blast hole 1 can release the gas in the deep coal seam and increase the air permeability of the coal seam, which is beneficial to improve the gas in the thick coal seam. Extraction effect. In general, the diameter of blast hole 1 for large-diameter deep hole blasting is 60-80mm, the depth of blast hole 1 is 50-60m, and the distance between blast hole 1 is 10-15m, depending on the thickness of the coal seam and the depth of gas drainage. Certainly.

[0045] Step two, such as image 3 , Figure 4 , Figure 5 , Image 6 As shown, the medicine roll 4 and the water bag 5 are respectively installed in the four-way vertically slit pipe 2, the four-way vertically slit pipe 2 and the medicine roll 4 and the four-way vertically slit pipe 2 and the water bag 5 are sequentially spaced by thread Connect by socket, and slowly push them into the blast hole 1 one by one. In the process of pushing the four-way vertical slit pipe 2, the prefabricated slits 3 of the slit pipe 2 in the adjacent blast holes 1 should be aligned with each other, so that the slit surface formed by the slits 3 of the adjacent slit pipes 2 is in the coal seam. A network of interconnected fractures is formed in the body. Among them, each of the four-way vertical slit pipes 2 is 1.4m long, the size of the prefabricated slits 3 is 250mm×4mm (length×width), and the distance between two adjacent prefabricated slits 3 in the axial direction is 50mm. The size of the medicine roll 4 and the water bag 5 is 38mm in diameter and 1200mm in length.

[0046] Since the slits have energy-gathering effects, four-way vertical slit tubes 2 are used to fill explosives, and the slits 3 of adjacent slit tubes 2 can be aligned with each other during the charging process, so that the explosion energy can be preferentially released along the direction of the prefabricated cracks , and form longer cracks in this direction. After the explosion, a radial wavy fissure zone is formed around the blast hole, and finally an interconnected fissure network is formed in the coal body, which increases the gas permeability of the coal body and improves the gas extraction effect of the coal body. The charge structure of charge volume 4 and water bag 5 is adopted to combine the energy of explosion stress wave, detonation wave, water jet and the coupling effect of detonation gas and water to act on the coal body together, improving the utilization of explosive explosion energy rate, greatly increasing the scope of coal fissures and increasing the gas permeability of coal.

[0047] Step 3. Charge the explosives in the way of four-way vertical slit pipe 2, drug roll 4 and water bag 5 at intervals, and detonate the explosives through double detonating cords 7, which are tied to the first slit at the bottom of the blast hole On the cross beam 8 at the bottom of the pipe 2, and within 10m from the orifice, use the yellow mud roll 6 to block the blast hole.

[0048] The four-way vertical slit pipe 2, the medicine roll 4 and the water bag 5 are used to charge the medicine at intervals. The water bag 5 ruptures to form a "water mist" generated by the water jet, which can effectively suppress or eliminate the sparks generated by the explosion of explosives, and improve the efficiency of high-gas mines. The safety of the explosion operation reduces the risk of gas disasters such as gas explosions in coal mines, and ensures the safe production of coal mines.

[0049] Step 4: Fill the remaining two blastholes 1 sequentially, then tie up the detonating cords 7 of each blasthole, detonate all the blastholes at the same time, and complete the anti-permeability construction of the low-permeability coal seam by the deep-hole directional pre-splitting blasting.

[0050] Of course, each parameter in the above-mentioned steps is only a preferred parameter in the specific implementation process. Parameters such as the depth, spacing, and charge of the blast hole 1 also need to be considered comprehensively according to the characteristics of the specific coal seam, and its values ​​​​can not be unified. Let me repeat.