A method for rapid excavation of rock tunnels assisted by hydraulic fracturing

Abstract

The present invention discloses a method for rapid excavation of a rock tunnel assisted by hydraulic fracturing, comprising the following steps: determining the minimum ground stress direction of the comprehensive excavation working face; arranging a plurality of said fracturing holes according to the minimum ground stress direction, and locating them at different positions; opening a plurality of radial grooves distributed at intervals on each of said fracturing holes; using a high-pressure water pump to perform segmented backward hydraulic fracturing on each of said fracturing holes, forming hydraulic cracks from said radial grooves; lowering the rated water pressure of the high-pressure water pump, and performing pressure-maintaining water injection on said fracturing holes. In the present invention, the fracturing holes are arranged at different positions to form hydraulic cracks in different directions, thereby reducing the strength and integrity of the rock mass to a greater extent and improving the efficiency of comprehensive excavation.

Description

Technical Field

[0001] The invention relates to the technical field of coal mine excavation, and in particular to a hydraulic fracturing-assisted comprehensive excavation rock tunnel rapid excavation method. Background Art

[0002] Rock tunnel excavation construction is a complex process with multiple procedures carried out alternately. Rock breaking, gangue removal and support are the three main processes. According to different rock breaking processes, tunnel excavation methods can be divided into two categories: drilling and blasting and comprehensive excavation. The drilling and blasting method uses drilling and blasting to break rocks; the comprehensive excavation method uses mechanical rock breaking, and the main equipment is the tunnel boring machine. The drilling and blasting method is suitable for environments with harder rock, but it has the following disadvantages: 1) The blasting effect causes great damage to the surrounding rock and easily induces instability of the surrounding rock; 2) The tunnel excavation speed is slow; 3) The construction safety is poor. The comprehensive excavation method is suitable for environments with softer rock. When encountering hard and complete rock, the tunnel boring machine pick wears seriously. In addition, the dust generated during mechanical rock breaking is relatively large. Therefore, it is crucial to reduce the integrity of the rock mass in advance by pre-splitting before comprehensive excavation to improve the efficiency of comprehensive excavation.

[0003] In the prior art, patent publication number CN105840199A and patent name "A method for comprehensive excavation of rock tunnels with static blasting and tunnel boring machine" discloses a method for comprehensive excavation of rock tunnels with static blasting and tunnel boring machine, in which multiple circles of blast holes are excavated on the tunnel excavation working face, and the expansion agent filled in the blast holes is expanded by using the resistance wire to generate heat, thereby causing cracks in the rock mass, thereby destroying the integrity of the rock mass, reducing the rock strength, and assisting the tunnel boring machine in excavation. However, this method has the following disadvantages: 1) There is too much dust on the excavation working face, which affects the workers' vision and health; 2) A large number of boreholes need to be excavated, and expansion agents and resistance wires need to be arranged in each borehole, resulting in numerous processes and affecting the excavation efficiency of each shift; 3) The direction and size of the cracks generated by the expansion agent after expansion are uncontrollable, and the degree of damage to the rock mass may not reach the ideal state. Therefore, it is difficult to achieve an ideal pre-cracking effect by using expansion agents instead of explosives.

[0004] In the prior art, patent publication number CN101975066A, patent name "Method for Rapid Excavation of Coal Rock Lanes" discloses a method for rapid excavation of coal rock lanes by hydraulic fracturing. This method fully opens and extends the original cracks in the coal rock mass and promotes their mutual penetration by arranging long boreholes in the excavation section, so as to achieve the purpose of increasing permeability, eliminating sudden changes, and safe and rapid excavation. However, this method has the following defects: 1) It is difficult to ensure the cracking morphology of hydraulic cracks; 2) It ignores the influence of ground stress on hydraulic fracturing. Under certain ground stress conditions, it cannot be guaranteed that the hydraulic cracks will expand in the expected direction.

[0005] In the prior art, patent publication number CN106150507A and patent name "A method for rapid tunneling by hydraulic fracturing and segmented blasting" discloses a method for rapid tunneling by hydraulic fracturing and segmented blasting, which includes the following three steps: the first step is to increase the cracks in the rock mass by hydraulic pre-fracture and the free surface required for blasting pre-fracture in the second step; the second step is to carry out blasting pre-fracture in four drill holes arranged in a diamond shape around the hydraulic pre-fracture borehole to promote further expansion of the cracks in the rock mass; the third step is to inject chemical solution into the hydraulic pre-fracture borehole to soften the rock and reduce the rock strength. Through these three steps, the integrity of the rock mass and the strength of the rock are reduced, the tunneling speed of the tunneling machine is increased, and the dust on the working surface is suppressed. However, this method has the following disadvantages: 1) The selection of chemical solution and the optimal solubility fitting of the chemical solution involve many mechanical and physical parameters of the surrounding rock, which makes this step cumbersome and complicated; 2) The soaking time required for the chemical solution is too long, which affects the tunneling efficiency. 3) The influence of the minimum principal stress on hydraulic fracturing is not taken into account. If the direction of the minimum principal stress is not parallel to the borehole axis, the hydraulic cracks formed cannot provide more free surfaces for the blasting process in the two boreholes as expected by this method.

[0006] In the prior art, patent publication number CN107083967A and patent name "Method and system for using hydraulic fracturing technology to assist tunnel boring machines in excavating extremely hard rocks" discloses a method for using hydraulic fracturing technology to assist tunnel boring machines in excavating extremely hard rocks. Although this method takes into account the impact of different minimum geostress directions on the borehole layout, the layout direction of each borehole is the same, all along the tunnel excavation direction. Therefore, the hydraulic cracks formed under certain geostress conditions expand in the horizontal direction and do not improve the efficiency of rock tunnel excavation. In addition, in this method, the hydraulic cracks cannot penetrate each other, and the rock mass will only be "divided" into larger blocks by hydraulic crack groups in the same direction, and the integrity of the rock mass is only reduced to a limited extent.

[0007] In summary, the hydraulic cracks generated by the prior art when pre-splitting the rock mass at the excavation working face all extend in the same direction, and no hydraulic crack groups with different directions are formed to achieve the connection between the hydraulic cracks. Therefore, the prior art has a very limited effect on reducing the integrity of the rock mass.

[0008] Therefore, it is necessary to design a hydraulic fracturing-assisted comprehensive excavation rock tunnel rapid excavation method that can reduce the rock mass strength and integrity to a greater extent and improve the comprehensive excavation efficiency. Summary of the invention

[0009] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a hydraulic fracturing assisted comprehensive excavation rock tunnel rapid excavation method that can reduce the strength and integrity of the rock mass to a greater extent and improve the comprehensive excavation efficiency.

[0010] The technical solution of the present invention provides a method for rapid excavation of a hydraulic fracturing-assisted fully-mechanized rock tunnel, comprising the following steps:

[0011] Determine the direction of minimum ground stress in the comprehensive excavation working face;

[0012] According to the direction of the minimum geostress, a plurality of the fracturing holes are arranged and located at different positions;

[0013] A plurality of radial grooves are provided at intervals on each of the fracturing holes;

[0014] Using a high-pressure water pump to perform segmented backward hydraulic fracturing on each of the fracturing holes, forming hydraulic cracks from the radial grooves;

[0015] The rated water pressure of the high-pressure water pump is lowered to perform pressure-maintaining water injection into the fracturing hole.

[0016] Furthermore, the direction of the minimum geostress is parallel to the axial direction of the tunnel, or perpendicular to the axial direction of the tunnel along a horizontal plane, or perpendicular to the axial direction of the tunnel along a vertical plane.

[0017] Furthermore, when the minimum geostress direction is parallel to the tunnel axis direction, a plurality of mutually parallel fracturing holes are arranged parallel to the tunnel axis direction.

[0018] Furthermore, the fracturing holes include three, namely, a first fracturing hole, a second fracturing hole and a third fracturing hole, the openings of the first fracturing hole, the second fracturing hole and the third fracturing hole are distributed in a triangular shape in the cross-section of the excavation tunnel, the first fracturing hole on the left side of the cross-section of the excavation tunnel and the second fracturing hole on the right side of the cross-section of the excavation tunnel are located at the same level, and the third fracturing hole located in the middle of the cross-section of the excavation tunnel is arranged near the top of the cross-section of the excavation tunnel.

[0019] Furthermore, when the direction of the minimum geostress is perpendicular to the tunnel axis along a horizontal plane, a plurality of fracturing holes are arranged in a horizontal plane and inclined to the tunnel axis, and the plurality of fracturing holes face at least two directions.

[0020] Furthermore, the fracturing holes include three, namely, a first fracturing hole, a second fracturing hole and a third fracturing hole. The first fracturing hole opening of the first fracturing hole near the top of the tunnel section and the second fracturing hole opening of the second fracturing hole near the bottom of the tunnel section are located on the left side of the tunnel section, and the third fracturing hole opening of the third fracturing hole located in the middle of the tunnel section is located on the right side of the tunnel section.

[0021] Furthermore, when the direction of the minimum geostress is perpendicular to the tunnel axis along a vertical plane, a plurality of fracturing holes are arranged in a horizontal plane and inclined to the tunnel axis, and the plurality of fracturing holes face at least two directions.

[0022] Furthermore, the fracturing holes include three, namely a first fracturing hole, a second fracturing hole and a third fracturing hole. The first fracturing hole opening of the first fracturing hole on the left side of the excavation tunnel section and the second fracturing hole opening of the second fracturing hole on the right side of the excavation tunnel section are located at the top of the excavation tunnel section, and the third fracturing hole opening of the third fracturing hole located in the middle of the excavation tunnel section is located at the bottom of the excavation tunnel section.

[0023] Furthermore, the step of opening a plurality of radial grooves distributed at intervals on each of the fracturing holes further comprises:

[0024] A first radial groove is cut on the first fracturing hole and the second fracturing hole;

[0025] A second radial groove is cut on the third fracturing hole, and the second radial groove corresponds to a middle position adjacent to the first radial groove.

[0026] Furthermore, the step of using a high-pressure water pump to perform segmented backward hydraulic fracturing on each of the fracturing holes further includes:

[0027] Firstly, the first fracturing hole and the second fracturing hole are fractured to form a first hydraulic crack;

[0028] Then, the third fracturing hole is fractured to form a second hydraulic fracture, wherein the first hydraulic fracture intersects with the second hydraulic fracture.

[0029] After adopting the above technical solution, the following beneficial effects are achieved:

[0030] In the present invention, according to the direction of minimum ground stress, the fracturing holes are arranged in multiple positions and located at different positions, and multiple radial grooves are arranged on the fracturing holes, and then hydraulic cracks are formed at the radial grooves, and finally water is injected by pressure maintenance to achieve the purpose of water injection softening and reducing rock strength. In the present invention, the fracturing holes are arranged at different positions to form hydraulic cracks in different directions, which can reduce the strength and integrity of the rock mass to a greater extent and improve the comprehensive excavation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. It should be understood that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In the drawings:

[0032] Figure 1It is a flow chart of the method for rapid excavation of a rock tunnel assisted by hydraulic fracturing in the present invention;

[0033] Figure 2 This is a cross-sectional view of the arrangement of fracturing holes when the direction of the minimum ground stress is parallel to the tunnel axis in the first embodiment of the present invention;

[0034] Figure 3 This is a cross-sectional view of the arrangement of the fracturing holes when the direction of the minimum ground stress is parallel to the tunnel axis in the first embodiment of the present invention;

[0035] Figure 4 It is a plan view of the arrangement of the fracturing holes when the direction of the minimum ground stress is parallel to the axis of the tunnel in the first embodiment of the present invention;

[0036] Figure 5 The diagram is a diagram of the cutting positions of the fracturing holes and the predicted extension of the hydraulic cracks when the direction of the minimum ground stress is parallel to the axis of the roadway in the first embodiment of the present invention;

[0037] Figure 6 It is a cross-sectional view of the arrangement of the fracturing holes when the minimum ground stress is along a horizontal plane perpendicular to the axis of the tunnel in the second embodiment of the present invention;

[0038] Figure 7 It is a cross-sectional view of the arrangement of the fracturing holes when the direction of the minimum ground stress is along a horizontal plane perpendicular to the axis of the tunnel in the second embodiment of the present invention;

[0039] Figure 8 It is a plan view of the arrangement of the fracturing holes when the direction of the minimum ground stress is along a horizontal plane perpendicular to the axis of the tunnel in the second embodiment of the present invention;

[0040] Fig. 9 It is a diagram showing the location of the fracturing hole cut and the predicted extension of the hydraulic crack when the direction of the minimum ground stress is perpendicular to the tunnel axis along the horizontal plane in the second embodiment of the present invention;

[0041] Fig.10 It is a cross-sectional view of the arrangement of the fracturing holes when the direction of the minimum ground stress is along a vertical plane perpendicular to the axis of the tunnel in the third embodiment of the present invention;

[0042] Fig.11 It is a cross-sectional view of the arrangement of the fracturing holes when the direction of the minimum ground stress is along a vertical plane perpendicular to the axis of the tunnel in the third embodiment of the present invention;

[0043] Fig.12 It is a plan view of the arrangement of the fracturing holes when the direction of the minimum ground stress is along a vertical plane perpendicular to the axis of the tunnel in the third embodiment of the present invention;

[0044] Fig.13 It is a diagram showing the location of the fracturing hole cutting and the predicted extension of the hydraulic crack when the direction of the minimum geostress is along a vertical plane perpendicular to the axis of the tunnel in the third embodiment of the present invention.

[0045] Reference table of reference numerals:

[0046] 1. The first fracturing hole; 2. The second fracturing hole; 3. The third fracturing hole; 4. The section of the tunnel; 5. The opening of the first fracturing hole; 6. The opening of the second fracturing hole; 7. The opening of the third fracturing hole; 8. The radial grooves, the first radial grooves 81, the second radial grooves 82; 9. The first hydraulic crack; 10. The second hydraulic crack. DETAILED DESCRIPTION

[0047] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0048] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a variety of structural modes and implementation modes that can be replaced by those skilled in the art can be replaced with each other. Therefore, the following specific implementation modes and drawings are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the whole of the present invention or as a limitation or restriction to the technical solution of the invention.

[0049] The directional terms such as up, down, left, right, front, back, front, back, top, bottom, etc. mentioned or may be mentioned in this specification are defined relative to the structures shown in the drawings. They are relative concepts and may change accordingly according to different positions and different usage conditions. Therefore, these or other directional terms should not be interpreted as restrictive terms.

[0050] In some embodiments of the present invention, Figure 1 As shown, the hydraulic fracturing assisted comprehensive excavation rock tunnel rapid excavation method comprises the following steps:

[0051] Step S1: determining the direction of minimum ground stress of the comprehensive excavation working face;

[0052] Step S2: arranging a plurality of fracturing holes at different positions according to the direction of minimum geostress;

[0053] Step S3: opening a plurality of radial grooves distributed at intervals on each fracturing hole;

[0054] Step S4: using a high-pressure water pump to perform segmented backward hydraulic fracturing on each fracturing hole, forming hydraulic cracks from the radial grooves;

[0055] Step S5: lowering the rated water pressure of the high-pressure water pump to perform pressure-maintaining water injection into the fracturing hole.

[0056] In this embodiment, multiple fracturing holes are arranged according to the direction of minimum ground stress, and are located at different positions, and multiple radial grooves are arranged on the fracturing holes, and then hydraulic cracks are formed at the radial grooves, and the hydraulic cracks face different directions. Finally, water injection is performed to soften the rock and reduce its strength. In the present invention, the fracturing holes are arranged at different positions to form hydraulic cracks facing different directions, which can reduce the strength and integrity of the rock mass to a greater extent and improve the efficiency of comprehensive excavation.

[0057] Preferably, step S2 further includes:

[0058] Step S201: some advanced exploration holes that are consistent with the parameters of the fracturing holes to be drilled, such as angles and positions, can be used as all or part of the fracturing holes. Using the advanced exploration holes as part of the fracturing holes can save fracturing costs.

[0059] Preferably, to ensure the accuracy of hydraulic fracturing and to ensure that cracks starting from the radial grooves can be formed, step S4 further includes:

[0060] Step S401: Use an expandable straddle sealer to seal each radial slot 8, and use segmented backward hydraulic fracturing for the fracturing hole.

[0061] Furthermore, the direction of the minimum geostress may be: the direction of the minimum geostress is parallel to the axis direction of the tunnel, or is perpendicular to the axis direction of the tunnel along a horizontal plane, or is perpendicular to the axis direction of the tunnel along a vertical plane.

[0062] Embodiment 1:

[0063] like Figure 2-5 As shown in FIG. 1 , when the minimum ground stress direction is parallel to the tunnel axis direction, multiple mutually parallel fracturing holes are arranged parallel to the tunnel axis direction. σ3 is the tunnel axis direction.

[0064] In step S2, Figure 2-4 As shown, the fracturing holes are arranged into three, namely the first fracturing hole 1, the second fracturing hole 2 and the third fracturing hole 3, the openings of the first fracturing hole 1, the second fracturing hole 2 and the third fracturing hole 3 are respectively the first fracturing hole opening 5, the second fracturing hole opening 6 and the third fracturing hole opening 7, the three openings are distributed in a triangular shape on the tunnel section 4, the first fracturing hole 1 on the left side of the tunnel section 4 and the second fracturing hole 2 on the right side of the tunnel section 4 are located at the same level, and the third fracturing hole 3 located in the middle of the tunnel section 4 is arranged near the top of the tunnel section 4.

[0065] In step S3, Figure 5As shown, a special tool is used to open radial grooves 8 for each fracturing hole. Among them, 9 first radial grooves 81 are cut at intervals of 3m in the first fracturing hole 1 and the second fracturing hole 2 on the left side and the right side of the tunnel section 4 as the initial weak surface for hydraulic fracturing; 8 second radial grooves 82 are cut in the third fracturing hole 3 located in the middle of the tunnel section 4 as the weak surface for hydraulic fracturing, and each second radial groove 82 in the third fracturing hole 3 is located in the middle position between the first radial grooves 81 in the adjacent fracturing holes.

[0066] In step S4, Figure 5 As shown, a high-pressure water pump is used to perform segmented backward hydraulic fracturing on each fracturing hole. The fracturing sequence of the fracturing holes is as follows: first, the first fracturing hole 1 and the second fracturing hole 2 on the left side and the right side of the tunnel section 4 are fractured, and then the third fracturing hole 3 in the middle of the tunnel section 4 is fractured, and the intersecting first hydraulic cracks 9 and second hydraulic cracks 10 are formed under the stress shadow effect, thereby increasing the number of joint groups in different directions in the rock mass.

[0067] In the first embodiment, three mutually parallel fracturing holes are provided, and intersecting first hydraulic cracks 9 and second hydraulic cracks 10 are formed between adjacent fracturing holes, thereby increasing the cracks in different directions of the rock mass, reducing the strength and integrity of the rock mass to a greater extent, and improving the comprehensive excavation efficiency.

[0068] Optionally, the present invention is not limited to three fracturing holes, but may also be two or more than three fracturing holes.

[0069] Embodiment 2:

[0070] like Figure 6-9 As shown, when the direction of minimum ground stress is perpendicular to the tunnel axis along the horizontal plane, a plurality of fracturing holes are arranged in the horizontal plane and inclined to the tunnel axis, and the plurality of fracturing holes face at least two directions.

[0071] In step S2, Figure 6-8 As shown, the fracturing holes are arranged to include three, namely the first fracturing hole 1, the second fracturing hole 2 and the third fracturing hole 3. The opening of the first fracturing hole 1 near the top of the tunnel section 4 and the opening of the second fracturing hole 2 near the bottom of the tunnel section 4 are located on the left side of the tunnel section 4, and the opening of the third fracturing hole 3 located in the middle of the tunnel section 4 is located on the right side of the tunnel section 4.

[0072] In step S3, Fig. 9As shown, nine first radial grooves 81 are cut at intervals of 3 m in the first fracturing hole 1 and the second fracturing hole 2 near the top and bottom of the tunnel section 4 as initial weak surfaces for hydraulic fracture initiation, and eight second radial grooves 82 are cut in the third fracturing hole 3 located in the middle of the tunnel section 4 as weak surfaces for hydraulic fracture initiation, and each second radial groove 82 of the third fracturing hole 3 is located in the middle position between the first radial grooves 81 in adjacent fracturing holes.

[0073] In step S4, Fig. 9 As shown, firstly, the first fracturing hole 1 and the second fracturing hole 2 near the top and the bottom of the tunnel section 4 are fractured, and then the third fracturing hole 3 in the middle of the tunnel section 4 is fractured, and the intersecting first hydraulic cracks 9 and the second hydraulic cracks 10 are formed under the stress shadow effect, thereby increasing the number of joint groups in different directions in the rock mass.

[0074] In Example 2, three fracturing holes are set up, which extend in different directions and form intersecting first hydraulic cracks 9 and second hydraulic cracks 10 between adjacent fracturing holes, thereby increasing the cracks in different directions of the rock mass, reducing the strength and integrity of the rock mass to a greater extent, and improving the comprehensive excavation efficiency.

[0075] Embodiment three:

[0076] like Figure 10-13 As shown, when the direction of minimum ground stress is perpendicular to the tunnel axis along the vertical plane, a plurality of fracturing holes are arranged in a horizontal plane and inclined to the tunnel axis, and the plurality of fracturing holes face at least two directions.

[0077] In step S2, Figure 10-12 As shown, the fracturing holes are arranged to include three, namely the first fracturing hole 1, the second fracturing hole 2 and the third fracturing hole 3. The opening of the first fracturing hole 1 on the left side of the tunnel section 4 and the opening of the second fracturing hole 2 on the right side of the tunnel section 4 are located at the top of the tunnel section 4, and the opening of the third fracturing hole 3 located in the middle of the tunnel section 4 is located at the bottom of the tunnel section 4.

[0078] Arrange S3, such as Fig.13 As shown, nine first radial grooves 81 are cut at intervals of 3 m in the first fracturing hole 1 and the second fracturing hole 2 on the left side and the right side of the tunnel section 4 as initial weak surfaces for hydraulic fracture initiation, and eight second radial grooves 82 are cut in the third fracturing hole 3 located in the middle of the tunnel section 4 as weak surfaces for hydraulic fracture initiation, and each second radial groove 82 of the third fracturing hole 3 is located in the middle position between the first radial grooves 81 in adjacent fracturing holes.

[0079] In step S4, Fig.13 As shown, firstly, the first fracturing hole 1 and the second fracturing hole 2 on the left side and the right side of the tunnel section 4 are fractured, and then the third fracturing hole 3 in the middle of the tunnel section 4 is fractured, and the intersecting first hydraulic cracks 9 and second hydraulic cracks 10 are formed under the stress shadow effect, increasing the number of joint groups in different directions in the rock mass. The pump is stopped each time the fracturing fluid flows out from the adjacent fracturing holes, and a new round of fracturing is performed at the next predetermined position.

[0080] In Example 2, three fracturing holes are set up, which extend in different directions and form intersecting first hydraulic cracks 9 and second hydraulic cracks 10 between adjacent fracturing holes, thereby increasing the cracks in different directions of the rock mass, reducing the strength and integrity of the rock mass to a greater extent, and improving the comprehensive excavation efficiency.

[0081] The above-mentioned technical scheme of the present invention has the following advantages: the present invention proposes corresponding hole layout schemes according to different ground stress conditions, thereby improving the deficiency that the traditional hydraulic fracturing-assisted comprehensive excavation rock tunnel excavation technology is only applicable to one ground stress condition; the present invention utilizes the stress shadow effect to change the expansion direction of some hydraulic cracks, so that the hydraulic cracks formed in the rock mass are interconnected, which reduces the integrity of the rock mass to a greater extent compared with the traditional hydraulic fracturing-assisted comprehensive excavation rock tunnel excavation technology, and significantly improves the excavation speed of the rock tunnel; each fracturing hole is pressure-maintained and injected with water after the fracturing process is completed, so as to achieve the purpose of softening by water injection, reducing the rock strength and further improving the comprehensive excavation efficiency.

[0082] The invention is suitable for assisting comprehensive excavation of rock tunnels and has the advantages of strong controllability, safety and reliability, simple operation, low cost, etc.

[0083] The above description is only the principle and preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this field, several other modifications can be made based on the principle of the present invention, which should also be considered as the protection scope of the present invention.

Claims

1. A hydraulic fracturing-assisted fully-mechanized rock tunnel rapid excavation method, characterized in that: The following steps are involved: Determine the direction of minimum ground stress in the fully mechanized excavation working face; Arranging a plurality of fracturing holes at different positions according to the direction of the minimum ground stress; A plurality of radial grooves are provided on each of the fracturing holes at intervals; Using a high-pressure water pump to perform segmented backward hydraulic fracturing on each of the fracturing holes, forming hydraulic cracks from the radial grooves; Lowering the rated water pressure of the high-pressure water pump to maintain pressure and inject water into the fracturing holes; when the direction of the minimum ground stress is perpendicular to the tunnel axis along the horizontal plane, arranging a plurality of fracturing holes located in the horizontal plane and obliquely arranged with respect to the tunnel axis, the plurality of fracturing holes facing at least two directions, the fracturing holes including three, namely, a first fracturing hole, a second fracturing hole, and a third fracturing hole; a first fracturing hole opening of the first fracturing hole near the top of the tunneling tunnel section and a second fracturing hole opening of the second fracturing hole near the bottom of the tunneling tunnel section are located on the left side of the tunneling tunnel section, and a third fracturing hole opening of the third fracturing hole located in the middle of the tunneling tunnel section is located on the right side of the tunneling tunnel section; When the direction of the minimum ground stress is perpendicular to the direction of the tunnel axis along the vertical plane, a plurality of fracturing holes are arranged in a horizontal plane and inclined to the tunnel axis, and the plurality of fracturing holes face at least two directions. The fracturing holes include three, namely, a first fracturing hole, a second fracturing hole and a third fracturing hole. The first fracturing hole opening of the first fracturing hole on the left side of the tunnel section and the second fracturing hole opening of the second fracturing hole on the right side of the tunnel section are located at the top of the tunnel section, and the third fracturing hole opening of the third fracturing hole located in the middle of the tunnel section is located at the bottom of the tunnel section.

2. The hydraulic fracturing-assisted fully-mechanized rock tunnel rapid excavation method according to claim 1 is characterized in that: The step of forming a plurality of radial grooves spaced apart on each of the fracturing holes further comprises: A first radial groove is cut on the first fracturing hole and the second fracturing hole; A second radial groove is cut on the third fracturing hole, and the second radial groove corresponds to a middle position adjacent to the first radial groove.

3. The hydraulic fracturing-assisted fully-mechanized rock tunnel rapid excavation method according to claim 2 is characterized in that: The step of using a high-pressure water pump to perform staged backward hydraulic fracturing on each of the fracturing holes further includes: First, fracturing the first fracturing hole and the second fracturing hole to form a first hydraulic crack; The third fracturing hole is then fractured to form a second hydraulic fracture, wherein the first hydraulic fracture intersects with the second hydraulic fracture.

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