A tunnel excavation method based on borehole convection heat cracking

Abstract

The application discloses a tunnel efficiency-improving excavation method based on drilling convection heat breaking, and belongs to the technical field of tunnel construction; the excavation method comprises drilling structure partition control, high-pressure water jet directional cutting, high-temperature steam convection heat breaking and differential charging blasting; the application forms through cracks among blast holes by combining high-pressure water jet directional cutting with high-temperature steam convection heating technology, and simultaneously performs heat breaking treatment, so that the tunnel driving efficiency and blasting efficiency are effectively improved; the rock mass pre-cracking and energy release are realized by high-pressure water jet directional cutting, and the possibility of rock burst is reduced; the application is suitable for hard rock tunnel excavation engineering such as granite.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tunnel construction, and particularly relates to a tunnel efficiency-enhanced excavation method based on drilling convection heat cracking, which is suitable for hard rock tunnel engineering such as granite. BACKGROUND

[0002] In tunnel engineering construction, blasting excavation is one of the key processes. The traditional blasting method mainly relies on the blasting power of explosives to break rocks. However, due to the natural high strength and toughness of rocks, the blasting effect is often unsatisfactory, the rock breaking range is limited, and there are problems such as low excavation efficiency, large disturbance of surrounding rock, and serious overbreak and underbreak. In addition, high ground stress hard rock is prone to rock burst, which has great safety hazards. SUMMARY

[0003] The application overcomes the shortcomings of the prior art and provides a tunnel efficiency-enhanced excavation method based on drilling convection heat cracking. The three-level collaborative control mechanism of drilling structure zoning control, high-pressure water jet directional cutting and high-temperature steam convection heating is used to realize accurate rock breaking, which can effectively improve the tunnel blasting excavation efficiency, realize rock pre-cracking and energy release, reduce overbreak and underbreak, and reduce environmental hazards.

[0004] The application is implemented by the following technical solutions:

[0005] A tunnel efficiency-enhanced excavation method based on drilling convection heat cracking, comprising the following steps:

[0006] Step 1: Drilling structure zoning control:

[0007] Radiate outward along the tunnel center to divide into four functional areas: core area, transition area, expansion area and contour forming area;

[0008] Arrange multiple slotting eyes in the core area, and arrange multiple auxiliary eyes in the transition area, expansion area and contour forming area;

[0009] Step 2: High-pressure water jet directional cutting:

[0010] Cut the four functional areas using high-pressure water jet; make the multiple slotting eyes and the multiple auxiliary eyes in each area interpenetrate through the cutting channels; the cutting sequence is: cutting from the core area to the contour forming area in sequence;

[0011] Step 3: High-temperature steam convection heat cracking:

[0012] Inject steam from the core area to the contour forming area according to the gradient trend of decreasing temperature by area, so as to realize convection heat cracking;

[0013] Step 4: Differentiated charging blasting:

[0014] The explosives are loaded into all the cutting eyes and auxiliary eyes, and the loading concentration of the auxiliary eyes is less than that of the cutting eyes; and the initiation is performed in sequence from the core area to the profile forming area.

[0015] Further, the cutting eyes in the double-layer rectangular nested structure are arranged in the core area: the inner layer is the air holes arranged in a rectangle, and the outer layer is the charge holes arranged in a rectangle.

[0016] Further, the midpoint O1 of the lower edge of the outer layer rectangle is taken as the positioning reference point, and the multiple auxiliary eyes in the transition area, the expansion area and the profile forming area are arranged as a semicircular array with O1 as the center.

[0017] Further, the multiple first-layer auxiliary eyes are arranged in the transition area; the multiple first-layer auxiliary eyes form a semicircular array with a radius of R1.

[0018] The second-layer auxiliary eyes and the third-layer auxiliary eyes are arranged in the expansion area; the multiple second-layer auxiliary eyes form a semicircular array with a radius of R2; the multiple third-layer auxiliary eyes form a semicircular array with a radius of R3; the second-layer auxiliary eyes and the third-layer auxiliary eyes are equally divided into multiple fan units in the circumferential direction.

[0019] The fourth-layer auxiliary eyes and the peripheral eyes are arranged in the profile forming area; the multiple fourth-layer auxiliary eyes form a semicircular array with a radius of R4; the multiple peripheral eyes form a semicircular array with a radius of R5; the fourth-layer auxiliary eyes and the peripheral eyes are equally divided into multiple fan units in the circumferential direction; R5>R4>R3>R2>R1.

[0020] Further, the first straight cutting channel is provided between the adjacent two air holes, the second straight cutting channel is provided between the adjacent two charge holes, and the oblique cutting channel is provided between the air hole and the adjacent charge hole.

[0021] The fourth straight cutting channel is provided between the second-layer auxiliary eyes in each fan unit, the fifth straight cutting channel is provided between the third-layer auxiliary eyes in each fan unit, and the first radial straight channel is provided between the second-layer auxiliary eyes and the adjacent third-layer auxiliary eyes in each fan unit.

[0022] The sixth straight cutting channel is provided between the fourth-layer auxiliary eyes in each fan unit, the seventh straight cutting channel is provided between the peripheral eyes, and the second radial straight channel is provided between the fourth-layer auxiliary eyes and the adjacent peripheral eyes in each fan unit.

[0023] Further, the core region is subjected to high-temperature steam convection heat cracking: steam is first injected into the outer layer of the charge hole, and the steam flows into the inner layer of the hole along the oblique cutting channel; after switching, the inner layer of the hole is converted into a steam injection hole, and steam is injected into the hole, and the steam flows into the outer layer of the charge hole in the opposite direction along the oblique cutting channel, which is one injection and return cycle;

[0024] The steam injected into the core region has a temperature of 550-600℃ and a pressure of 1.5-3.8MPa, each injection and return cycle is 6-8 minutes, and 8-10 injection and return cycles are performed.

[0025] Further, the transition region is subjected to high-temperature steam convection heat cracking: the first layer of auxiliary holes is divided into two groups, the first layer of the first group of auxiliary holes is the auxiliary holes on both sides and in the middle, and the first layer of the second group of auxiliary holes is the remaining auxiliary holes; steam is first injected into the first layer of the first group of auxiliary holes, and the steam flows into the first layer of the second group of auxiliary holes along the third straight line cutting channel; after switching, steam is injected into the first layer of the second group of auxiliary holes, and the steam flows into the first layer of the first group of auxiliary holes along the third straight line cutting channel, which is one injection and return cycle;

[0026] The steam injected into the transition region has a temperature of 500-550℃ and a pressure of 1.3-3.0MPa, each injection and return cycle is 8-10 minutes, and 6-8 injection and return cycles are performed.

[0027] Further, the expansion region is subjected to high-temperature steam convection heat cracking: steam is injected into the second layer of auxiliary holes in each group of fan-shaped units, and the steam flows into the third layer of auxiliary holes along the first radial straight line channel, and after switching, the third layer of auxiliary holes is converted into a steam injection hole, and steam is injected into the third layer of auxiliary holes, and the steam flows into the second layer of auxiliary holes from the first radial straight line channel, which is one injection and return cycle;

[0028] The steam injected into the expansion region has a temperature of 450-500℃ and a pressure of 1.0-2.5MPa, each injection and return cycle is 10-12 minutes, and 5-6 injection and return cycles are performed.

[0029] Further, the contour forming region is subjected to high-temperature steam convection heat cracking: in each group of fan-shaped units in the contour forming region, the fourth layer of auxiliary holes serves as the injection hole, and the peripheral hole serves as the return hole, steam is injected into the fourth layer of auxiliary holes in each group of fan-shaped units, and the steam flows unidirectionally along the second radial straight line channel and flows into the peripheral hole;

[0030] The steam injected into the contour forming region has a temperature of 400-450℃ and a pressure of 0.8-2.0MPa, and the unidirectional injection time is 25-30 minutes.

[0031] Further, the holes, charge holes, first layer of auxiliary holes, second layer of auxiliary holes, third layer of auxiliary holes, fourth layer of auxiliary holes, and peripheral holes are charged; the charge concentration of the holes and the charge holes is 0.3-0.5kg / m;

[0032] The charge concentration of the first layer auxiliary eye, the second layer auxiliary eye, the third layer auxiliary eye and the fourth layer auxiliary eye is 0.2-0.4 kg / m; the charge concentration of the peripheral eye is 0.1-0.25 kg / m; and the differential time of detonation is 5-50 ms.

[0033] The beneficial effects of the present application relative to the prior art are:

[0034] 1. The present application forms through cracks between blast holes by high-pressure water jet directional cutting combined with high-temperature steam convection heating technology, and simultaneously performs thermal fracturing treatment, thereby effectively improving the tunneling efficiency and blasting efficiency.

[0035] 2. The present application controls the drilling structure by partition, uses grid cutting and one-way heat injection in the contour forming area to make the overbreakage ≤5 cm and the half-hole retention rate ≥90%.

[0036] 3. The present application uses high-temperature steam circulation to reduce the dust concentration to below 30 mg / m³, thereby effectively improving the working environment.

[0037] 4. The present application realizes rock mass pre-splitting and energy release by high-pressure water jet directional cutting, thereby reducing the possibility of rock burst. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 Figure 1 is a schematic diagram of the tunnel drilling structure partition structure.

[0039] Figure 2 Figure 2 is a schematic diagram of the through structure after cutting in the core area.

[0040] Figure 3 Figure 3 is a schematic diagram of the through structure after cutting in the transition area.

[0041] Figure 4 Figure 4 is a schematic diagram of the through structure after cutting in the expansion area.

[0042] Figure 5 Figure 5 is a schematic diagram of the through structure after cutting in the contour forming area.

[0043] Figure 6 Figure 6 is a schematic diagram of the tunnel drilling structure crack through.

[0044] In the figure:

[0045] 1 is a core area, 2 is a transition area, 3 is an expansion area, 4 is a contour forming area, 101 is a void hole, 102 is a charging hole, 103 is a second linear cutting channel, 104 is a first linear cutting channel, 105 is an oblique cutting channel, 201 is a first layer first group of auxiliary eyes, 202 is a first layer second group of auxiliary eyes, 203 is a third linear cutting channel, 301 is a second layer auxiliary eye, 302 is a third layer auxiliary eye, 303 is a fourth linear cutting channel, 304 is a fifth linear cutting channel, 305 is a first radial linear channel, 401 is a fourth layer auxiliary eye, 402 is a peripheral eye, 403 is a sixth linear cutting channel, 404 is a seventh linear cutting channel, and 405 is a second radial linear channel. DETAILED DESCRIPTION

[0046] In order to make the technical problems to be solved by the present application, the technical solutions and beneficial effects clearer and more apparent, the present application will be further described in detail in conjunction with the embodiments and drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application. The technical solutions of the present application are described in detail below in conjunction with the embodiments and drawings, but the protection scope is not limited thereto.

[0047] Reference Figures 1 to 6 The embodiment provides a tunnel efficiency excavation method based on drilling convection heat cracking. The tunnel is a granite tunnel, and a full-face method is used for construction. The specific steps of the efficiency excavation method are as follows:

[0048] Step one, drilling structure partition control:

[0049] Radiate outward along the tunnel center to divide into four functional areas: core area 1, transition area 2, expansion area 3 and contour forming area 4;

[0050] 1.1, structure of core area 1:

[0051] Eight slotting eyes are arranged in the core area 1 to form a double-layer nested structure: the inner layer is four void holes 101, and the four void holes 101 are arranged in a square with a side length S1=0.6 m; the outer layer is four charging holes 102, and the four charging holes 102 are arranged in a square with a side length S2=1.8 m; the square formed by the four void holes 101 and the square formed by the four charging holes 102 are coaxially nested structures, and the lower edge midpoint O1 of the outer square is used as a positioning reference point. The depth of the void hole 101 and the charging hole 102 is 5 m.

[0052] 1.2, structure of transition area 2:

[0053] 7 first layer auxiliary holes are arranged in the transition zone 2 outside and around the core zone 1, the first layer auxiliary holes form a semicircular array with O1 as the center and R1 = 1.2 m as the radius, the plane where the semicircular array is located is perpendicular to the tunneling direction, and the hole spacing S3 of the first layer auxiliary holes is 0.5 m; the first layer auxiliary holes are divided into two groups, the first layer first group auxiliary holes 201 are three auxiliary holes on both sides and in the middle, and the first layer second group auxiliary holes 202 are the remaining four auxiliary holes.

[0054] 1.3, the structure of the extension zone 3:

[0055] The second layer auxiliary holes 301 and the third layer auxiliary holes 302 are arranged in the extension zone 3 outside and around the transition zone 2; the second layer auxiliary holes 301 form a semicircular array with O1 as the center and R2 = 1.8 m as the radius; the hole spacing S4 of the second layer auxiliary holes 301 is 0.6 m; the third layer auxiliary holes 302 form a semicircular array with O1 as the center and R3 = 2.4 m as the radius; the hole spacing S5 of the third layer auxiliary holes 302 is 0.75 m;

[0056] The second layer auxiliary holes 301 and the third layer auxiliary holes 302 are equally divided into 5 groups of fan units (36° / group) along the circumference, each group containing 2 second layer auxiliary holes 301 and 3 third layer auxiliary holes 302.

[0057] 1.4, the structure of the contour forming zone 4:

[0058] The fourth layer auxiliary holes 401 and the peripheral eyes 402 are arranged in the contour forming zone 4 outside and around the extension zone 3; the fourth layer auxiliary holes 401 form a semicircular array with O1 as the center and R4 = 3.0 m as the radius, and the hole spacing S6 of the fourth layer auxiliary holes 401 is 0.7 m; the peripheral eyes 402 form a semicircular array with O1 as the center and R5 = 3.3 m as the radius, and the hole spacing S7 of the peripheral eyes 402 is 0.7 m;

[0059] The fourth layer auxiliary holes 401 and the peripheral eyes 402 are equally divided into 5 groups of fan units along the circumference, each group containing 4 fourth layer auxiliary holes 401 and 5 peripheral eyes 402.

[0060] The depth of the first layer first group auxiliary holes 201, the first layer second group auxiliary holes 202, the second layer auxiliary holes 301, the third layer auxiliary holes 302, the fourth layer auxiliary holes 401 and the peripheral eyes 402 is 3-5 m.

[0061] The diameter of the hole 101, the charging hole 102, the first layer first group auxiliary holes 201, the first layer second group auxiliary holes 202, the second layer auxiliary holes 301, the third layer auxiliary holes 302, the fourth layer auxiliary holes 401 and the peripheral eyes 402 is 42±1 mm.

[0062] Step two: high pressure water jet directional cutting

[0063] The four functional areas are cut by high pressure water jet, and the cutting sequence is: core area 1→ transition area 2→ expansion area 3→ contour forming area 4; the jet pressure is 220 MPa, the cutting time is 6 minutes per hole, and the crack depth is ≥1.8 m; the cutting method for each functional area is to cut from both ends to the middle at the same time.

[0064] 2.1, cutting of core area 1:

[0065] After cutting, the two adjacent empty holes 101 are connected through the first straight cutting channel 104, and the length of the straight cutting channel 104 is 0.6 m; the two adjacent charge holes 102 are connected through the second straight cutting channel 103; the empty hole 101 and the adjacent charge hole 102 are connected through the oblique cutting channel 105; the oblique angle β of the oblique cutting channel 105 is 40°, and the length is 0.8 m.

[0066] 2.2, cutting of transition area 2:

[0067] The two adjacent first layer auxiliary eyes are connected through the third straight cutting channel 203, forming a ring-shaped crack network; the width of the third straight cutting channel 203 is 3 mm.

[0068] 2.3, cutting of expansion area 3:

[0069] The two second layer auxiliary eyes 301 in each group of fan-shaped units are connected through the fourth straight cutting channel 303, and the two third layer auxiliary eyes 302 in each group of fan-shaped units are connected through the fifth straight cutting channel 304; the second layer auxiliary eye 301 and the adjacent two third layer auxiliary eyes 302 in each group of fan-shaped units are connected through the first radial straight channel 305, and the length of the first radial straight channel 305 is 0.9 m. In the expansion area 3, three triangular crack networks are formed in each group of fan-shaped units.

[0070] 2.4, cutting of contour forming area 4:

[0071] The four fourth layer auxiliary eyes 401 in each group of fan-shaped units are connected through the sixth straight cutting channel 403, and the five peripheral eyes 402 are connected through the seventh straight cutting channel 404; and the fourth layer auxiliary eye 401 and the adjacent two peripheral eyes 402 in each group of fan-shaped units are connected through the second radial straight channel 405, and the length of the second radial straight channel 405 is 0.5 m. Seven triangular through networks are formed in each group of fan-shaped units.

[0072] Step three: high temperature steam convection heat cracking

[0073] The steam is injected with a gradient trend of gradually decreasing temperature by area from the core area 1 to the profile forming area 4, and high-efficiency convective thermal cracking is realized through a mixed connection "injection-back" alternating heating path; specifically:

[0074] 3.1, high-temperature steam convective thermal cracking is performed on the core area 1:

[0075] The charging holes 102 and the empty holes 101 are divided into a "4-injection 4-back alternating circulation system", steam is first injected into the outer 4 charging holes 102, and the steam flows into the inner 4 empty holes 101 along the oblique cutting channel 105; after switching, the inner 4 empty holes 101 become injection eyes and inject steam, and the steam flows into the outer 4 charging holes 102 along the oblique cutting channel 105 in the opposite direction, which is one injection-back cycle.

[0076] The steam injected into the core area 1 has a temperature of 580°C and a pressure of 3.0 MPa, and each injection-back cycle is 7 minutes, and 10 injection-back cycles are performed.

[0077] 3.2, high-temperature steam convective thermal cracking is performed on the transition area 2:

[0078] Steam is first injected into the first layer first group of auxiliary eyes 201, and the steam flows into the first layer second group of auxiliary eyes 202 along the third straight cutting channel 203; after switching, steam is injected into the first layer second group of auxiliary eyes 202, and the steam flows into the first layer first group of auxiliary eyes 201 along the third straight cutting channel 203, which is one injection-back cycle;

[0079] The steam injected into the transition area 2 has a temperature of 520°C and a pressure of 2.2 MPa, and each injection-back cycle is 9 minutes, and 7 injection-back cycles are performed.

[0080] 3.3, high-temperature steam convective thermal cracking is performed on the expansion area 3:

[0081] A "2-injection 3-back alternating unit" is formed within each group of fan-shaped units: steam is injected into the second layer auxiliary eyes 301 within each group of fan-shaped units, and the steam flows into the third layer auxiliary eyes 302 along the first radial straight channel 305, and after switching, the third layer auxiliary eyes 302 become injection eyes, steam is injected into the third layer auxiliary eyes 302, and the steam flows into the second layer auxiliary eyes 301 from the first radial straight channel 305, which is one injection-back cycle;

[0082] The steam injected into the expansion area 3 has a temperature of 480°C and a pressure of 1.8 MPa, and each injection-back cycle is 11 minutes, and 6 injection-back cycles are performed; 5 groups of fan-shaped units are executed synchronously.

[0083] 3.4, high-temperature steam convective thermal cracking is performed on the profile forming area 4:

[0084] In each group of fan-shaped units in the contour forming area 4, 4 fourth layer auxiliary eyes 401 serve as injection eyes, and 5 peripheral eyes 402 serve as backflow eyes, forming a "one-way heat convection system"; that is, steam is injected into the fourth layer auxiliary eyes 401 in each group of fan-shaped units, and the steam unidirectionally flows along the second radial linear channel 405 and flows into the peripheral eyes 402; a pre-fracturing-light blasting synergistic effect is formed.

[0085] The steam injected into the contour forming area 4 has a temperature of 420°C and a pressure of 1.5 MPa, and the one-way injection time is 25 minutes. The five groups of fan-shaped units are executed synchronously.

[0086] Step four, differential charging blasting:

[0087] The amount of charge is adjusted according to the degree of rock weakening in each area, the amount of explosive in the core area 1 is reduced by 50% to 70%, and the amount of explosive in the contour forming area 4 is reduced by 30% to 40%. High-temperature resistant emulsion explosive (temperature resistance ≥600°C) is selected as the explosive, an initiation network is set, and 1-9 non-electric millisecond detonators and plastic booster tubes are used as blasting materials. The initiation sequence is core area 1→ transition area 2→ expansion area 3→ contour forming area 4, and the millisecond time is 5-50 ms;

[0088] Specifically, in the embodiment:

[0089] The empty hole 101, the charging hole 102, the first layer first group of auxiliary eyes 201, the first layer second group of auxiliary eyes 202, the second layer auxiliary eyes 301, the third layer auxiliary eyes 302, the fourth layer auxiliary eyes 401 and the peripheral eyes 402 are charged; wherein:

[0090] The charging concentration of the empty hole 101 and the charging hole 102 is 0.4 kg / m (originally 0.7 kg / m, saving 0.3 kg / m of explosive);

[0091] The charging concentration of the first layer first group of auxiliary eyes 201, the first layer second group of auxiliary eyes 202, the second layer auxiliary eyes 301, the third layer auxiliary eyes 302 and the fourth layer auxiliary eyes 401 is 0.3 kg / m (originally 0.6 kg / m, saving 0.3 kg / m of explosive);

[0092] The charging concentration of the peripheral eyes 402 is 0.2 kg / m (originally 0.35 kg / m, saving 0.15 kg / m of explosive);

[0093] Initiation is performed, and the initiation sequence is: core area 1→ transition area 2→ expansion area 3→ contour forming area 4, from inside to outside in sequence, and the millisecond time is 25 ms.

[0094] Step five, blasting effect evaluation:

[0095] Rock fragmentation: the proportion of rock blocks with a particle size of ≤10 cm is 85%, and the fragmentation efficiency is increased by 40%;

[0096] Forming accuracy: The overbreak is 1.8 cm and the half-hole retention rate is 92% by a three-dimensional laser scanner;

[0097] Environmental indicators: Dust concentration is 28 mg / m³, and rock burst occurrence rate is reduced by 55%;

[0098] Construction efficiency: The cycle footage is improved by 30% to 4.2 m / cycle.

[0099] The above is a further detailed description of the present application in combination with specific preferred embodiments, which cannot be regarded as limiting the specific embodiments of the present application to this. For ordinary skilled persons in the technical field to which the present application belongs, a number of simple deductions or substitutions can be made without departing from the present application, which should be regarded as falling within the scope of patent protection determined by the submitted claims.

Claims

1. A tunneling method based on the drilling convection heat cracking, characterized in that, The method comprises the following steps: Step one, drilling structure partition control: Along the center of the tunnel, it is divided into four functional areas: core area (1), transition area (2), expansion area (3) and contour forming area (4); In the core area (1), a double-layer rectangular nested structure of slotting eyes is arranged: the inner layer is a rectangular array of empty holes (101), and the outer layer is a rectangular array of charging holes (102); a plurality of auxiliary eyes are arranged in the transition area (2), the expansion area (3) and the contour forming area (4) respectively; With the lower edge midpoint O1 of the outer layer rectangle as the positioning reference point, the plurality of auxiliary eyes in each area of the transition area (2), the expansion area (3) and the contour forming area (4) are arranged as a semicircular array with O1 as the center; a plurality of first layer auxiliary eyes are arranged in the transition area (2); the plurality of first layer auxiliary eyes form a semicircular array with a radius of R1; In the expansion area (3), a second layer auxiliary eye (301) and a third layer auxiliary eye (302) are arranged; a plurality of second layer auxiliary eyes (301) form a semicircular array with a radius of R2; a plurality of third layer auxiliary eyes (302) form a semicircular array with a radius of R3; the second layer auxiliary eye (301) and the third layer auxiliary eye (302) are equally divided into a plurality of fan-shaped units along the circumference; In the contour forming area (4), a fourth layer auxiliary eye (401) and a peripheral eye (402) are arranged; a plurality of fourth layer auxiliary eyes (401) form a semicircular array with a radius of R4; a plurality of peripheral eyes (402) form a semicircular array with a radius of R5; the fourth layer auxiliary eye (401) and the peripheral eye (402) are equally divided into a plurality of fan-shaped units along the circumference; R5>R4>R3>R2>R1; Between two adjacent empty holes (101), a first straight cutting channel (104) is penetrated; between two adjacent charging holes (102), a second straight cutting channel (103) is penetrated; between the empty hole (101) and the adjacent charging hole (102), an oblique cutting channel (105) is penetrated; between two adjacent first layer auxiliary eyes, a third straight cutting channel (203) is penetrated; Between the second layer auxiliary eyes (301) in each fan-shaped unit, a fourth straight cutting channel (303) is penetrated; between the third layer auxiliary eyes (302) in each fan-shaped unit, a fifth straight cutting channel (304) is penetrated; between the second layer auxiliary eye (301) and the adjacent third layer auxiliary eye (302) in each fan-shaped unit, a first radial straight channel (305) is penetrated; Between the fourth layer auxiliary eyes (401) in each fan-shaped unit, a sixth straight cutting channel (403) is penetrated; between the peripheral eyes (402), a seventh straight cutting channel (404) is penetrated; and between the fourth layer auxiliary eye (401) and the adjacent peripheral eye (402) in each fan-shaped unit, a second radial straight channel (405) is penetrated; Step two, high-pressure water jet directional cutting: Cutting the four functional areas by high-pressure water jet; making the multiple cut slots and the multiple auxiliary slots in each area interpenetrate through the cutting channels; the cutting sequence is: cutting from the core area (1) to the profile forming area (4) in sequence; Step three, high-temperature steam convection thermal cracking: Injecting steam from the core area (1) to the profile forming area (4) according to the gradient trend of gradually decreasing temperature, realizing convection thermal cracking; Step four, differential charging blasting: Charging all the cut slots and auxiliary slots with explosives, the charging concentration of the auxiliary slots is less than that of the cut slots; detonating from the core area (1) to the profile forming area (4) in sequence.

2. A tunneling method based on the drilling convection heat breakage according to claim 1, characterized in that, High-temperature steam convection thermal cracking on the core area (1): first injecting steam into the outer charging holes (102), and the steam flows into the inner empty holes (101) along the inclined cutting channels (105); after switching, the inner empty holes (101) become steam injection holes, and the steam flows into the outer charging holes (102) along the inclined cutting channels (105) in the opposite direction, which is one injection and return cycle; The temperature of the steam injected into the core area (1) is 550-600℃, the pressure is 1.5-3.8MPa, each injection and return cycle is 6-8 minutes, and 8-10 injection and return cycles are carried out.

3. A tunneling method based on the drilling convection heat breakage according to claim 1, characterized in that, High-temperature steam convection thermal cracking on the transition area (2): the first layer of auxiliary slots is divided into two groups, the first layer first group of auxiliary slots (201) is the auxiliary slots on both sides and in the middle, and the first layer second group of auxiliary slots (202) is the remaining auxiliary slots; first injecting steam into the first layer first group of auxiliary slots (201), and the steam flows into the first layer second group of auxiliary slots (202) along the third straight cutting channel (203); after switching, injecting steam into the first layer second group of auxiliary slots (202), and the steam flows into the first layer first group of auxiliary slots (201) along the third straight cutting channel (203), which is one injection and return cycle; The temperature of the steam injected into the transition area (2) is 500-550℃, the pressure is 1.3-3.0MPa, each injection and return cycle is 8-10 minutes, and 6-8 injection and return cycles are carried out.

4. A tunneling method based on the drilling convection heat breakage according to claim 1, characterized in that, High-temperature steam convection thermal cracking on the expansion area (3): injecting steam into the second layer of auxiliary slots (301) in each group of fan-shaped units, and the steam flows into the third layer of auxiliary slots (302) along the first radial straight channel (305); after switching, the third layer of auxiliary slots (302) become steam injection holes, and the steam flows into the second layer of auxiliary slots (301) from the first radial straight channel (305), which is one injection and return cycle; The temperature of the steam injected into the expansion area (3) is 450-500℃, the pressure is 1.0-2.5MPa, each injection and return cycle is 10-12 minutes, and 5-6 injection and return cycles are carried out.

5. A tunneling method based on the drilling convection heat breakage according to claim 1, characterized in that, High-temperature steam convection thermal fracture is conducted on the profile forming area (4): in each group of fan-shaped units in the profile forming area (4), the fourth layer of auxiliary eyes (401) are used as injection eyes, and the peripheral eyes (402) are used as return flow eyes, steam is injected into the fourth layer of auxiliary eyes (401) in each group of fan-shaped units, and the steam flows in one direction along the second radial linear channel (405) and flows into the peripheral eyes (402); The temperature of the steam injected into the profile forming area (4) is 400-450 ℃, the pressure is 0.8-2.0 MPa, and the one-way injection time is 25-30 minutes.

6. A tunneling method based on the drilling convection heat breakage according to claim 1, characterized in that, The holes (101), the charging holes (102), the first layer of auxiliary eyes, the second layer of auxiliary eyes (301), the third layer of auxiliary eyes (302), the fourth layer of auxiliary eyes (401) and the peripheral eyes (402) are charged; the charging concentration of the holes (101) and the charging holes (102) is 0.3-0.5 kg / m; The charging concentration of the first layer of auxiliary eyes, the second layer of auxiliary eyes (301), the third layer of auxiliary eyes (302) and the fourth layer of auxiliary eyes (401) is 0.2-0.4 kg / m; the charging concentration of the peripheral eyes (402) is 0.1-0.25 kg / m; and the detonation delay time is 5-50 ms.

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