CN117846590A - Laser water jet grooving method and application thereof in loosening blasting - Google Patents

Abstract

The invention provides a method for grooving by laser water jet, which comprises the following steps: a loose explosion hole is formed in a rock body, and the hole wall of the loose explosion hole is cut by using a high-energy laser beam to form a spiral groove surrounding the hole wall; during cutting, the spiral cutting groove formed by the laser head and cutting is continuously washed by water flow. The invention adopts a laser water jet composite spiral grooving mode to overcome the defects of the traditional mechanical grooving clamping tool, holding drill and the like, solves the problems of difficult steering and low efficiency of the water jet grooving drill bit, can adjust the parameters of laser cutting according to the hardness of the rock mass, realizes the control of the cutting depth, and improves the blasting effect. The method is applied to loose blasting of the rock mass, the direction of the spiral groove is changed between the axial direction and the radial direction, and the range of a fracture area is increased; the explosion energy is only used for expanding the slit, so that the energy utilization rate is improved, the expansion length of the crack is increased, the crushing area is enlarged, and the economic benefit is improved while the generation of rock explosion is prevented.

Description

Laser water jet grooving method and application thereof in loosening blasting

Technical Field

The invention belongs to the technical field of loosening blasting, and particularly relates to a laser water jet grooving method and application of the laser water jet grooving method in loosening blasting.

Background

With the continuous increase of mineral demand and the increasing exhaustion of shallow resources, most mines enter a deep mining stage and have become the development trend of future mining. With the increase of the mining depth, high stress characteristics are revealed, geological disasters such as rock burst, rock burst and the like frequently occur, and the difficulty of mining deep mineral resources is increased. Rock burst is a natural phenomenon, and generally occurs in a process of mining or excavating a tunnel, and in some areas with high stress, the stress in the rock body is suddenly released, so that the rock body is suddenly broken like explosion and falls off and splashed, and huge sound and air waves are generated, so that when the rock burst occurs, a mine can be greatly damaged.

The pressure relief technology can effectively solve the problem of local high stress concentration in the deep part of the mine and prevent and treat dynamic geological disasters of the mine. The pressure relief technology commonly used at present comprises hydraulic pressure relief, a pressure relief groove or a pressure relief roadway, blasting pressure relief and drilling pressure relief technologies; the water injection pressure of the hydraulic pressure relief technology is relatively small, and the hydraulic pressure relief technology is only suitable for soft rock or crack development areas; when the pressure relief groove or the pressure relief roadway technology is adopted, the distance between the pressure relief groove or the pressure relief roadway and the stress concentration area is difficult to determine.

In order to avoid rock burst, loose blasting is usually adopted to destroy the region with larger stress in advance, so that the internal stress is released in advance. After blasting, although cracks are generated on the coal body around the blast hole, partial stress is unloaded, the coal body far away from the blast hole is compacted because of no compensation space for blasting cracks and breakage, new stress concentration is formed at a distance, the coal body moves towards the working surface when the working surface is the free surface for blasting, and broken rock can collapse towards the working surface or the coal body at the hole sealing section generates a cut-opening at the working surface; meanwhile, energy generated by explosion can directly act on rock mass around the wall of the blast hole to generate a rock mass crushing area, and deep rock mass is not crushed, so that internal stress of hard rock is not well released.

In order to obtain a better loosening blasting effect, a control hole (without charging) is introduced to serve as a free surface, and the control hole is punched near the loosening blasting hole to play roles in controlling blasting direction and compensating blasting crack space; because a large number of penetrating cracks are generated in the direction of the connecting line between the blasting holes and the control holes, the number of the control holes in other directions needs to be increased to obtain a better loosening blasting effect. Therefore, the grooving is carried out by adopting a mechanical or high-pressure water jet method at present, and a large number of axial and radial cracks are formed around the loose and burst holes to form 'control holes'; at this time, cracks generated by blasting can extend along the cutting direction along the inside of the rock mass, so that the pressure relief effect is improved.

However, when the mechanical grooving method is adopted, harder coal rock mass is encountered, the mechanical drill bit is easy to clamp the shell, and the drill bit is greatly damaged, so that the mechanical grooving efficiency is low, and the cost is high; when the high-pressure water jet formed by adopting the high-pressure water jet is used for spirally grooving the wall of the loose and burst hole, the water jet nozzle is difficult to control in rotation, and the cutting efficiency of the high-pressure water jet is lower when the water jet nozzle encounters harder coal rock, and the cut rock mass fragments can remain in the slot, so that a grooving mode with high efficiency, low cost, short construction period and convenient operation is needed.

In summary, on the premise of ensuring the outburst prevention effect, the control hole is formed by grooving in a short time by using a high-efficiency low-cost technology, so that the pressure relief effect is improved, and finally, the purpose of high yield and high efficiency is achieved.

Disclosure of Invention

The invention aims at providing a laser water jet grooving method which is simple in process, convenient to operate, safe, reliable, good in control and good in effect.

The second object of the invention is to provide an application of the method of laser water jet grooving in loose blasting.

One of the achievement purposes of the invention adopts the technical proposal that: a method of laser water jet grooving is provided, comprising the steps of: a loose explosion hole is formed in a rock body, and the hole wall of the loose explosion hole is cut by using a high-energy laser beam to form a spiral groove surrounding the hole wall; in the cutting process, the laser head emitting the high-energy laser beam and the spiral cutting groove formed by cutting are continuously washed by water flow.

The general idea of the invention is as follows: aiming at the defects of the prior art, the invention provides a method for grooving by using laser water jet, which has the advantages of simple process, convenient operation, safety, reliability, good control and good effect. The high-energy light beam formed by the laser has the advantages of high precision, non-contact performance, high efficiency, strong adaptability and the like, and can avoid the problem of shell jamming possibly occurring in mechanical grooving and difficult steering encountered in the grooving process of the high-pressure water jet, thereby achieving good pressure relief effect and rock burst prevention and control purposes and simultaneously achieving economic benefit.

Further, considering that the thermal effect of laser is directly utilized to heat the rock mass layer, the rock mass layer is thermally damaged, rock mass fragments are generated simultaneously when the laser head is continuously pushed, and the obstruction is formed for the subsequent grooving operation.

Further, the laser generating the high-energy laser beam includes one of a carbon dioxide laser, a carbon monoxide laser, an yttrium aluminum garnet laser, and a fiber laser.

Preferably, the laser in the present invention employs a fiber laser. The working wavelength of the fiber laser is 1060-1080 nm, enough energy can be transmitted to a remote target through a long fiber, and the fiber laser has the characteristics of ultrahigh electro-optic conversion efficiency (30%), good beam quality, vehicle-mounted maneuverability, stability of equipment, maintenance-free property and the like. In addition, the fiber laser has high power, no maintenance and long service life, and is suitable for adopting a one-machine multi-machine mode, so that the fiber laser is more suitable for the laser water jet grooving method of the invention relative to other types of lasers, and can be better applied to loose blasting construction of rock mass layers.

Further, in the cutting process, the power of the laser is 400-1800W. According to the research, under the condition that the laser power is kept unchanged, as the irradiation time of laser is increased, the diameter of the laser drilling hole is increased, and the depth of the laser drilling hole is also increased, but after the irradiation time is increased to a certain range, the damage effect on the rock mass tends to be stable; under the condition that the laser power is kept unchanged, the smaller the laser irradiation distance is, the smaller the diameter of the hole on the surface of the rock mass is, the larger the depth is, and the smaller the irradiation distance is, the higher the rock breaking speed is. In the present invention, the irradiation time of the laser is set to 3 to 30 seconds, and the focal length of the laser (irradiation distance of the laser) is set to 4 to 12cm.

Further, the width of the spiral groove is 6-24 mm, the depth is 5-20 mm, and the gap between the grooves is 10-20 cm. Laser grooving can produce a very large range of slot sizes and high grooving speeds compared to conventional mechanical or aqueous grooving. The laser cut slot size can be adjusted based on the laser power and focusing system.

According to the invention, according to the difference of the material of rock mass around the wall of the loose blasting hole and the difference of hardness grade of the rock mass, technological parameters (including power, time, focal length and the like) in the laser grooving process are adjusted in a targeted manner, so that proper slot depth and width are generated, and better cutting and loose blasting effects are realized.

Further, the present invention classifies rock mass into four main categories according to its hardness and its solidity coefficient f: soft-softer rock mass: f=0.8 to 3; medium hard to relatively hard rock mass: f=3 to 8; firm rock mass: f=8 to 15; very strong rock mass: f=15 to 20. In combination with a great deal of research practice, the invention provides more suitable technological parameters for laser water jet grooving of rock masses with different firmness coefficients f:

preferably, for weak rock mass (f=0.8 to 3), the power of the laser is 400 to 600W, the irradiation time of the laser is 3 to 9s, the irradiation distance of the laser is 6 to 12cm, and the width of the formed slot is 10 to 24mm.

Preferably, for medium strong rock masses (f=3 to 8), the power of the laser is 600 to 1000W, the irradiation time of the laser is 5 to 15s, the irradiation distance of the laser is 6 to 10cm, and the width of the formed slot is 8 to 20mm.

Preferably, for hard rock masses (f=8 to 15), the power of the laser is 800 to 1400W, the irradiation time of the laser is 10 to 25s, the irradiation distance of the laser is 4 to 8cm, and the width of the formed slot is 8 to 16mm.

Preferably, for extremely strong rock masses (f=15 to 20), the power of the laser is 1000 to 1800W, the irradiation time of the laser is 15 to 30s, the irradiation distance of the laser is 4 to 6cm, and the width of the formed slot is 6 to 14mm.

Further, in the cutting process, the water flow is utilized to control the water flow nozzle and the laser head to synchronously move in the process of continuously flushing the laser head emitting the high-energy laser beam and the spiral cutting groove formed by cutting. By moving the nozzle and the cutting tool synchronously, it is ensured that the water jet from the water cooling system can directly cool the cutting area. In addition, the synchronous movement of the nozzle and the cutting tool ensures that the water jet does not interfere with the cutting process.

Preferably, the flow rate of the water flow is 10-20L/min, and when the hardness of the cut rock mass is high or the cutting speed is high, the water flow rate can be increased appropriately to enhance the cooling effect.

Preferably, the nozzle of the water stream sprays the water stream directly onto the cutting area, with the water pressure of the water stream being controlled between 1000-4000psi (about 69-276 bar). The high pressure water stream is able to penetrate sufficiently into the cutting area and make effective contact with the cutting site. In particular, the level of water pressure depends on the type of cutting tool and the hardness of the rock mass.

Preferably, the distance between the nozzle of the water flow and the laser head is 0.5-4 cm. The high-pressure water flow impacts the reverse impact generated by the groove to realize synchronous flushing of the laser head.

Preferably, after the cutting is completed, the water flow is continued to cool the laser head and flush the slot.

The second technical scheme adopted for realizing the purpose of the invention is as follows: there is provided the use of a method of laser water jet grooving in accordance with one of the objects of the present invention in loose blasting.

Further, the loosening blasting includes blasting of coal strata, and application scenes of deep underground tunnels, underground construction spaces and the like involving deep rock mass blasting.

Further, the method for cutting grooves by laser water jet provided by the invention is applied to loose blasting of coal strata, and comprises the following steps:

s1, processing a loose explosion hole penetrating through a coal bed in a rock body;

s2, cutting the hole wall of the loose explosion hole by using a high-energy laser beam to form a spiral groove surrounding the hole wall; in the cutting process, continuously flushing a laser head emitting high-energy laser beams and spiral grooves formed by cutting by utilizing water flow;

s3, filling explosive, installing an explosion system, and sealing the loose explosion hole;

and S4, detonating the detonation system, wherein in the detonation process, the detonation stress wave and the detonation gas expand along the bottom of the spiral cutting groove, and form extension cracks to the depth of the rock mass.

The method for cutting the slot by the laser water jet is applied to loose blasting of the coal stratum, and brings the following advantages: on one hand, after blasting, the coal body around the loose blasting hole is broken and loosened to form a pressure relief ring, so that the original concentrated stress zone of the rock body is moved to the deep part of the rock body; meanwhile, stress concentration caused by uneven hardness and geological structure of coal is eliminated, and stress in the coal body can be effectively reduced; on the other hand, the coal body cracks in front of the working face are increased due to loosening control blasting, and the cracks can further extend into the rock body along the cutting groove tip at the bottom of the spiral cutting groove, so that a blasting compensation space can be further provided for the blasted rock body, and the generation of rock burst can be effectively prevented and controlled.

Preferably, in step S1, the diameter of the loose blasting hole is 50-200 mm.

Preferably, in step S2, the spiral groove penetrates through the coal seam, and the axial length of the spiral groove is greater than the thickness of the coal seam.

Preferably, in step S3, the explosive with the detonator is placed into the PVC pipe, and is sent into the loose blasting hole, and then the PVC pipe filled with yellow sand is sent into the PVC pipe, and polyurethane is bound in the middle of each section of PVC pipe, so as to ensure that the PVC pipe is in the center of the loose blasting hole, and finally the loose blasting hole is plugged by yellow mud. The PVC pipe plays a role in guiding and transmitting energy in loosening blasting; the yellow mud is used for filling blasting pores, so that blasting effect and safety are enhanced.

Preferably, in step S4, the detonation system is an electric detonation system.

Compared with the prior art, the invention has the beneficial effects that:

(1) The invention provides a laser water jet grooving method, which overcomes the defects of the traditional mechanical grooving and high-pressure water jet grooving modes, and the high-energy laser beam can directionally slit all rock bodies, so that the problems of clamping a cutter, holding a drill and the like do not exist for weak rock bodies with more layers for crack development, a laser head is easy to turn, the grooving depth of a coal body is controllable, and the processing time is saved; the laser slotting depth can be adjusted at any time according to the thickness and the structure of the coal seam, so that a better blasting effect is realized. In addition, because the laser grooving in-process accompanies the washing effect of rivers, can in time cool off the maintenance equipment normal operating to the laser head, can be simultaneously smooth with loose the interior stone sediment clean up of hole that explodes, the going on of follow-up powder charge of being convenient for.

(2) The laser water jet grooving method provided by the invention is applied to loose blasting of deep rock bodies such as coal strata, the spiral grooving which is formed by the laser water jet grooving and rotates around the axis is changed between the axial direction and the radial direction, the grooving mode greatly increases the range of a crack area, the grooving density can be adjusted, the blasting block diameter is controlled, and the loose blasting requirement is completely met. The directional stress concentration of the spiral grooving tip ensures that the crack expands from the design direction of the grooving top, and the existence of new crack growth areas is restrained at the two sides of the grooving tip, so that other parts of the wall of the loose and burst hole are not damaged by impact load, explosion energy is only used for expanding the grooving, the energy utilization rate is improved, the expansion length of the crack is increased, and the crushing area is enlarged. The concentrated stress is further transferred to the deep part of the rock mass after the grooving, and the pressure relief effect is also achieved to a certain extent. The method for carrying out loosening blasting by using the laser water jet grooving can effectively prevent rock blasting, saves energy consumption, has low cost and short construction period, and has great application and popularization values.

Drawings

FIG. 1 is a schematic diagram of an apparatus used in a method of laser water jet grooving in accordance with an embodiment of the present invention;

FIG. 2 is a schematic view of a spiral slot formed by laser water jet slot according to an embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating an operation of a loosening blasting method according to an embodiment of the present invention;

FIG. 4 is a schematic illustration of the effect of applying laser water jet grooving to loose blasting in accordance with an embodiment of the present invention;

wherein, 1-rock mass; 2-coal bed; 3-loosening and bursting holes; 31-loosening the hole wall of the explosion hole; 4-energy optical fiber; 5-water flow; 6-water jet nozzles; 7-a laser head; 8-spiral grooving; 81-extending a crack; 9-yellow mud; 10-polyurethane; 11-PVC pipe; 12-yellow sand; 13-explosive; 14-detonator.

Detailed Description

The technical solutions of the present invention will be clearly and completely described in connection with the embodiments, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.

The invention will be further illustrated, but is not limited, by the following examples.

Example 1

Fig. 1 is a schematic structural diagram of an apparatus used in a method for cutting grooves by laser water jet according to the present embodiment, and the apparatus is applied to loose blasting of a coal formation. The rock mass type of the laser cut blast hole is sandstone (solidity coefficient f=1.2).

As shown in fig. 1, a coal bed 2 is arranged in a rock body 1 of sandstone, and a loose explosion hole penetrates through the rock body 1 and is communicated with the inside of the coal bed 2. The controllable high-energy laser generated by the laser is transmitted to the laser head 7 through the energy optical fiber 4, the high-energy laser acts on the coal rock of the drilling hole after being focused by the laser head 7, the coal rock is heated by utilizing the thermal effect of the laser, the coal rock is thermally destroyed, and the spiral cutting groove 8 (shown in fig. 2) rotating around the axis of the loose blasting hole 3 is formed around the hole wall 31 of the loose blasting hole. And the water flow emitted by the water jet nozzle 6 clears broken rock mass broken stone by thermal damage at the same time of high-energy laser action, so that high-speed rock breaking and high-efficiency grooving are realized. The laser adopts a fiber laser, and the working wavelength of the fiber laser is 1070nm; the distance between the nozzle of the water flow and the laser head is 3cm; the flow rate of the water flow is 15L/min, and the water pressure of the water flow is controlled to be about 1500 psi.

The loosening blasting method based on laser water jet grooving provided in this embodiment, as shown in fig. 3, includes the following steps:

step 1: drilling holes through the coal rock mass at selected positions by using a drilling machine to form loose explosion holes penetrating through the coal bed inside the coal rock mass; the rock mass thickness is 32m, the coal thickness is 3m, the hole depth of the loose explosion hole is 36m, and the aperture of the loose explosion hole is 113mm.

Step 2: the high-energy laser beam formed by the laser is used for cutting the hole wall of the loose and burst hole, and the parameters of the laser in the cutting process are controlled as follows: the power of the laser is 400W, the irradiation time of the laser is 4s, the irradiation distance of the laser is 8cm, the drill hole is spirally grooved at the position of 0.5m outwards from the starting end of the coal seam, the position of 0.5m outwards from the ending end of the coal seam is ended, a spiral jet slit is formed on the hole wall of the drill hole, the width of the formed slit is 12mm, the depth of the slit is 11mm, the distance between the slits is 15cm, and in the cutting process, the laser head and the formed spiral slit are continuously washed by water flow.

Step 3: after the laser water jet grooving is completed, through holes are formed, rock powder coal cinder in the loose blasting holes is cleaned, then explosive filled with detonators is placed into PVC pipes, the pipe length is 2m, 11 sections of PVC pipes are fed, then PVC pipes filled with yellow sand with the same length are fed into the loose blasting holes, polyurethane with the length of 0.5m is bound in the middle of each section, the PVC pipes are guaranteed to be fed into 4 sections in the center of the loose blasting holes, finally yellow mud is used for sealing holes, the length of each section of PVC pipe is 4m, the PVC pipes are tamped by a stick, and finally a detonation system is connected.

Step 4: and detonating the detonation system, wherein in the detonation process, the detonation stress wave and the detonation gas expand along the bottom of the spiral cutting groove to form extension cracks to the depth of the rock mass.

FIG. 4 is a schematic illustration of the effect of applying laser water jet grooving to loose blasting in accordance with an embodiment of the present invention; in conventional loose blasting, since there is no notch in the wall 31 of the loose blasting hole, energy generated by blasting directly acts on surrounding rock mass, thereby breaking the surrounding rock mass and creating a rock mass breaking zone. After the laser water jet spiral grooving provided by the invention is loosened and exploded, the spiral grooving 8 with the groove depth of 11mm is generated, the stress at the bottom position (grooving tip) of the spiral grooving 8 is weakest, and the energy generated by explosion can generate cracks from the bottom of the spiral grooving and expand outwards to form extension cracks 81, so that the utilization rate of the energy is improved, the expansion length of the cracks is increased, and the crushing area is enlarged.

Example 2

The embodiment provides a loosening blasting method based on laser water jet grooving, which is used for loosening blasting (firmness coefficient f=6) of granite during tunnel excavation, and comprises the following steps:

step 1: drilling holes on the granite at selected positions by using a drilling machine to form loose explosion holes; the thickness of the penetrated rock mass is 50m, the hole depth of the loose explosion hole is 55m, and the aperture of the loose explosion hole is 120mm.

Step 2: the high-energy laser beam formed by the laser is used for cutting the hole wall of the loose and burst hole, and the parameters of the laser in the cutting process are controlled as follows: the power of the laser is 1000W, the irradiation time of the laser is 5s, the irradiation distance of the laser is 10cm, a spiral jet flow slot is formed on the hole wall of the laser, the width of the formed slot is 8mm, the depth of the slot is 9mm, the interval between the slots is 10cm, and in the cutting process, the laser head and the spiral slot formed are continuously washed by water flow. The laser adopts a fiber laser, and the working wavelength of the fiber laser is 1070nm; the distance between the nozzle of the water flow and the laser head is 4cm; the flow rate of the water flow is 12L/min, and the water pressure of the water flow is controlled to be about 2000 psi.

Step 3: after the laser water jet grooving is completed, through holes are formed, rock powder coal cinder in the loose blasting holes is cleaned, then explosive filled with detonators is placed into PVC pipes, the pipe length is 2m, 14 sections of PVC pipes are fed, then PVC pipes filled with yellow sand with the same length are fed into the loose blasting holes, polyurethane with the length of 0.5m is bound in the middle of each section, the PVC pipes are guaranteed to be fed into the centers of the loose blasting holes for 5 sections, finally yellow mud is used for sealing holes, the length is 5m, the detonation system is connected.

Step 4: and detonating the detonation system, wherein in the detonation process, the detonation stress wave and the detonation gas expand along the bottom of the spiral cutting groove to form extension cracks to the depth of the rock mass.

In the embodiment, after the laser water jet spiral grooving is adopted for loosening blasting, the spiral grooving with the groove depth of 9mm is generated, the stress at the bottom position (the grooving tip) of the spiral grooving is weakest, the energy generated by blasting can generate cracks from the bottom of the spiral grooving and expand outwards to form extension cracks, the utilization rate of the energy is improved, and the expansion length of the cracks is increased, so that the crushing area is enlarged, and the economic benefit is improved while the generation of rock burst is prevented.

Example 3

The embodiment provides a loosening blasting method based on laser water jet grooving, which is used for loosening blasting (firmness coefficient f=12) of compact granite during tunnel excavation, and comprises the following steps:

step 1: drilling holes on the dense granite by using a drilling machine at a selected position to form loose explosion holes; wherein, the thickness of the penetrated rock mass is 43m, the hole depth of the loose explosion hole is 46m, and the aperture of the loose explosion hole is 117mm.

Step 2: the high-energy laser beam formed by the laser is used for cutting the hole wall of the loose and burst hole, and the parameters of the laser in the cutting process are controlled as follows: the power of the laser is 1400W, the irradiation time of the laser is 15s, the irradiation distance of the laser is 4cm, a spiral jet flow slot is formed on the hole wall of the laser, the width of the formed slot is 11mm, the depth of the slot is 8mm, the interval between the slots is 10cm, and in the cutting process, the laser head and the spiral slot formed are continuously washed by water flow. The laser adopts a fiber laser, and the working wavelength of the fiber laser is 1070nm; the distance between the nozzle of the water flow and the laser head is 3.5cm; the flow rate of the water flow is 16L/min, and the water pressure of the water flow is controlled to be about 2500 psi.

Step 3: after the laser water jet grooving is completed, through holes are formed, rock powder coal cinder in the loose blasting holes is cleaned, then explosive filled with detonators is placed into PVC pipes, the pipe length is 2m, 12 sections of PVC pipes are fed, then PVC pipes filled with yellow sand with the same length are fed into the loose blasting holes, polyurethane with the length of 0.5m is bound in the middle of each section, the PVC pipes are guaranteed to be fed into the centers of the loose blasting holes for 5 sections, finally yellow mud is used for sealing holes, the length is 6m, the detonation system is connected.

Step 4: and detonating the detonation system, wherein in the detonation process, the detonation stress wave and the detonation gas expand along the bottom of the spiral cutting groove to form extension cracks to the depth of the rock mass.

In the embodiment, after the laser water jet spiral grooving is adopted for loosening blasting, the spiral grooving with the groove depth of 8mm is generated, the stress at the bottom position (the grooving tip) of the spiral grooving is weakest, the energy generated by blasting can generate cracks from the bottom of the spiral grooving and expand outwards to form extension cracks, the utilization rate of the energy is improved, and the expansion length of the cracks is increased, so that the crushing area is enlarged, and the economic benefit is improved while the generation of rock burst is prevented.

The foregoing is merely illustrative of the preferred embodiments of the present invention and is not intended to limit the embodiments and scope of the present invention, and it should be appreciated by those skilled in the art that equivalent substitutions and obvious variations may be made using the teachings of the present invention, which are intended to be included within the scope of the present invention.

Claims (10)

1. A method of laser water jet grooving comprising the steps of:

a loose explosion hole is formed in a rock body, and the hole wall of the loose explosion hole is cut by using a high-energy laser beam to form a spiral groove surrounding the hole wall; in the cutting, a laser head emitting a high-energy laser beam and a spiral cutting groove formed by cutting are continuously washed by water flow.

2. The method of claim 1, wherein the laser that generates the high energy laser beam comprises one of a carbon dioxide laser, a carbon monoxide laser, an yttrium aluminum garnet laser, and a fiber laser.

3. The method according to claim 1, wherein the power of the laser is 400-1800W, the irradiation time of the laser is 3-30 s, and the focal length of the laser is 4-12 cm during the cutting process.

4. The method of claim 1, wherein the spiral kerfs have a width of 6 to 24mm, a depth of 5 to 20mm, and a kerf spacing of 10 to 20cm.

5. The method according to claim 1, wherein when the rock mass has a firmness factor f=0.8-3, the power of the laser is 400-600W, the irradiation time of the laser is 3-9 s, the irradiation distance of the laser is 6-12 cm, and the width of the formed slot is 10-24 mm.

6. The method according to claim 1, wherein when the rock mass has a firmness factor f=3 to 8, the power of the laser is 600 to 1000W, the irradiation time of the laser is 5 to 15s, the irradiation distance of the laser is 6 to 10cm, and the width of the formed slot is 8 to 20mm.

7. The method according to claim 1, characterized in that it comprises: when the firmness coefficient f=8-15 of the rock mass, the power of the laser is 800-1400W, the irradiation time of the laser is 10-25 s, the irradiation distance of the laser is 4-8 cm, and the width of the formed slot is 8-16 mm.

8. The method according to claim 1, wherein when the rock mass has a firmness factor f = 15-20, the power of the laser is 1000-1800W, the irradiation time of the laser is 15-30 s, the irradiation distance of the laser is 4-6 cm, and the width of the formed slot is 6-14 mm.

9. Use of a method based on a laser water jet grooving as claimed in any one of claims 1-8 in loose blasting.

10. The use according to claim 9, characterized by the steps of:

s1, processing a loose explosion hole penetrating through a coal bed in a rock body;

s2, cutting the hole wall of the loose explosion hole by using a high-energy laser beam to form a spiral groove surrounding the hole wall; in the cutting process, a laser head emitting high-energy laser beams and spiral cutting grooves formed by cutting are continuously washed by water flow;

s3, filling explosive, installing an explosion system, and sealing the loose explosion hole;

and S4, detonating the detonation system, and expanding the explosion stress wave and the explosive gas along the spiral cutting groove in the detonation process to form an extension crack deep into the rock mass.