Multidirectional energy-gathering presplitting multi-wedge straight cutting blasting method for hard rock roadway

Abstract

A hard rock roadway multidirectional energy-gathered pre-splitting multi-wedge straight cutting blasting method comprises the steps that a directional drill hole is drilled in the tunneling excavation direction, and multidirectional energy-gathered pre-splitting blasting is conducted in the drill hole through a multidirectional energy-gathered blasting device after hole forming, so that a multidirectional energy-gathered initial pre-splitting crack is generated in the hole wall of the drill hole; high-pressure water injection is carried out in the drill hole after multidirectional energy-gathered presplitting blasting, and a multidirectional energy-gathered initial presplitting crack is further expanded; and a multi-wedge straight slotting method is adopted for digging out the fractured rock mass in the multi-direction energy-gathered initial pre-crack area, and a large-size groove cavity is obtained. By adopting the slotting method provided by the invention, the drilling and blasting excavation footage of the existing hard rock roadway can be improved to 2.8 m to 3.2 m from the traditional 1.0 m to 1.5 m, and the footage efficiency is obviously improved by more than 250%. According to the breakthrough progress, the excavation speed and effect of the drilling and blasting method under the hard rock condition are remarkably improved, and a new technical path and a new solution are provided for rapid construction of the hard rock tunnel.

Description

Technical Field

[0001] The invention relates to the technical field of drilling and blasting excavation of full-section rock tunnels, and in particular to a multi-directional energy-gathering pre-splitting and multi-wedge straight-cutting blasting method for hard rock tunnels. Background Art

[0002] In the excavation of rock tunnels in coal mines in my country, two main methods are used: excavation by fully-mechanized excavators and drilling and blasting. For full-section rock tunnel excavation with rock hardness below f<7, the existing tunneling machines can basically achieve mechanized and rapid excavation, because the fully-mechanized excavator is a comprehensive mechanized equipment that integrates multiple functions such as excavation, rock loading, coal transportation, and even support and nailing. It mainly relies on the cutting teeth of the tunneling machine head to cut and crush the rock mass to achieve excavation. Compared with the drilling and blasting excavation process of drilling and blasting, it can increase the excavation progress by more than 30 times. Therefore, in the current coal mine tunnel excavation in my country, fully-mechanized excavators are mainly used for coal tunnel excavation and softer (f<7) rock tunnel excavation.

[0003] However, for full-section rock tunnels with rock hardness f>7, due to the hard rock, when using a comprehensive excavator to excavate, the excavation teeth are worn and consumed greatly. The replacement of a single excavator tooth head costs at least hundreds of thousands, and at most millions. In addition, the excavation speed is very slow, and the excavation cost per meter is extremely high. Therefore, drilling and blasting is still the main excavation method. When using the drilling and blasting method to excavate, according to the depth of the blasthole, it can be divided into: shallow hole smooth blasting (blasthole depth <1.8m); medium-deep hole smooth blasting (blasthole depth 1.8m~2.5m); deep hole smooth blasting (blasthole depth 2.5m~5.0m); ultra-deep hole smooth blasting (blasthole depth above 5.0m). When drilling and blasting, most of the drilling rigs in domestic coal mines use 2.6-meter drills. The footage of most hard rock tunnels in coal mines can generally only reach about 1.5 meters. The excavation speed is very slow and the efficiency is extremely low, which greatly delays the completion time of the large tunnel, further delaying the production of coal mines and significantly increasing construction costs. The main reason for this phenomenon is that when the rock is hard, it is difficult for the explosives to break and throw out the hard rock when drilling and blasting are used due to the hard rock. As a result, the trenching depth is very small and the trench cavity space is small, making it difficult to provide a larger and deeper free surface when the auxiliary eye is blasted. Ultimately, the blasting footage is low and the blasting excavation effect is very unsatisfactory.

[0004] At present, in various types of engineering blasting, although deep hole slot blasting methods such as oblique eye, straight eye, double wedge, multi-wedge, and wedge-straight mixed have been explored in deep hole slot blasting technology, when blasting the full-section hard rock slot, the deeper the blast hole, the stronger its clamping effect, especially when the rock is harder, it is difficult for the slot explosive to fully crush the rock, and the depth of the blasted rock mass is limited. Although slot blasting is implemented, the blasting crushing effect is weak, and it is difficult to achieve ideal rock crushing and throwing in the slot cavity, and it is impossible to form an ideal slot cavity. Therefore, how to achieve full crushing and throwing of hard rocks in the hard rock slot cavity area has become the main problem of the present invention to solve the low footage of hard rock slot. Summary of the invention

[0005] The object of the present invention is to provide a multi-directional energy-gathering pre-splitting and multi-wedge straight slot blasting method for a hard rock tunnel to solve the above-mentioned problems.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A multi-directional energy-gathering pre-splitting and multi-wedge straight slot blasting method for hard rock tunnels, comprising: Directional drilling is performed in the excavation direction. After the hole is formed, a multi-directional concentrated energy blasting device is used in the borehole for multi-directional concentrated energy pre-crack blasting, so that multi-directional concentrated energy initial pre-cracks are generated on the borehole wall; Implement high-pressure water injection into the borehole after multi-directional energy-gathering pre-splitting blasting to further expand the multi-directional energy-gathering initial pre-cracks; The multi-wedge straight trenching method is used to dig out the broken rock mass in the multi-directional energy-gathering initial pre-crack area to obtain a large-sized trench cavity.

[0007] Further, directional drilling is performed in the excavation direction, including: A kilometer-long directional drill is used to drill a hole with a diameter of 95mm-113mm and a length of 30m-100m along the center of the excavation tunnel.

[0008] Furthermore, after the hole is formed, a multi-directional concentrated energy blasting device is used in the borehole to perform multi-directional concentrated energy pre-crack blasting, so that multi-directional concentrated energy initial pre-cracks are generated on the borehole wall, including: A blasting energy focusing device for ultra-deep holes, with large diameter, segmented filling, six-way radiation energy focusing, and adjustable crack number is used to load explosives for multi-directional energy focusing blasting pre-cracking, which produces radial pre-cracks on the borehole wall.

[0009] Furthermore, high-pressure water injection is carried out in the borehole after the multi-directional energy-focused pre-splitting blasting, including: In the borehole after the multi-directional energy pre-splitting blasting, the packer is pressurized to expand the rubber tube and seal the large hole. Then, a high-pressure hose is used to connect the high-pressure pump to inject high-pressure water into the sealed large hole. Under the action of high-pressure water, the multi-directional energy pre-cracks are squeezed and torn by monitoring the water pressure. The initial crack length generated by the multi-directional energy blasting is expanded from 300mm to 500mm to 3000 to 4000mm, so that the rock in the central area is transformed from hard and intact rock to broken and fractured rock mass.

[0010] Furthermore, the multi-wedge straight trenching method is used to dig out the broken rock mass in the multi-directional energy-gathering initial pre-crack area to obtain a large-sized trench cavity, including: Drill holes in the pre-splitting and crushing area, then set peripheral holes with different spacings around the tunnel contour according to the soft rock lithology, and arrange auxiliary holes, peripheral holes and bottom holes in the area inside the peripheral holes and outside the groove hole area; Explosives are loaded into the slot holes, auxiliary holes, bottom holes and peripheral holes respectively, and micro-difference multiple blasting is carried out in the triple wedge straight holes.

[0011] Furthermore, slot drilling is performed in the pre-splitting and crushing zone, including: using a rock drilling rig to drill slot holes in the pre-splitting and crushing zone, wherein the slot holes with hole numbers 1 to 10 have a hole depth of 2.0 to 2.4 m, and an angle between the oblique hole and the face of the tunnel is 55 to 75°; the slot holes with hole numbers 11 to 18 have a hole depth of 3.2 m, and an angle between the oblique hole and the face of the tunnel is 75 to 85°; the central slot holes with hole numbers 19 to 10 use 90° straight holes.

[0012] Further, explosives are respectively loaded into the cut hole, the auxiliary hole, the bottom hole, and the peripheral hole, including: 1) For the slotted holes with hole numbers 1-10, each hole is divided into two sections, of which the bottom charge part is the second section in the hole, which is loaded with a 32mm diameter and 400mm long third-grade water-gel explosive, and the charge length accounts for 20% to 25% of the hole length. A 25ms delay electric detonator with a leg line and a detonating cord with the same length as the bottom charge are used; after the bottom charge is loaded, yellow mud is then stuffed to block the bottom charge part of the hole, and the blocking length is 500mm; then the first section in the hole is loaded, and the first section of the explosive body uses a 32mm diameter and 400mm long third-grade water-gel explosive, and the charge length accounts for 25% to 30% of the hole length. A 0ms delay electric detonator with a leg line and a detonating cord with the same length as the second section of the charge are used; then the hole is filled with yellow mud to seal the hole, and the yellow mud plugging filling length is not less than 0.5m, and the plugging length is 0.6m to 1.0m; 2) For the slotted holes with hole numbers 11-18, each hole is divided into two sections, of which the bottom charge part is the second section in the hole, which is loaded with 32mm diameter and 400mm long third-grade water-gel explosive, the length of which accounts for 20% to 25% of the hole length, and a Ⅲ-section 50ms time-delay electric detonator with a leg line and a detonating cord with the same length as the bottom charge of the hole are used; after the bottom charge part of the hole is filled, yellow mud is then stuffed to block the bottom charge part of the hole, with a blocking length of 500mm; then the first section in the hole is filled, and the first section of the explosive body uses a 32mm diameter and 400mm long third-grade water-gel explosive, the length of which accounts for 25% to 30% of the hole length, and a Ⅱ-section 25ms time-delay electric detonator with a leg line and a detonating cord with the same length as the second section of the charge are used; then the hole is sealed with yellow mud, and the length of the yellow mud plugging is not less than 0.5m, and the plugging length is 0.6m to 1.0m; 3) For the cutout holes with hole numbers 19-20, 1-2 sections of 32mm diameter and 400mm length three-grade water-gel explosives are placed at the bottom of the holes. The diameter of the drill hole is 42mm. The explosives are 32mm diameter and 400mm length three-grade water-gel explosives with an uncoupling coefficient of 1.31. The single hole is detonated by a foot line with a 50ms delay electric detonator of stage III. The charge is loaded forward and the hole is sealed with yellow mud. The length of the sealed hole is not less than 0.3m. After the charging of the groove eyes is completed, the auxiliary eyes, cave-in eyes, bottom eyes and peripheral eyes are filled according to the design requirements of normal smooth blasting or concentrated energy smooth blasting. Among them, the auxiliary eyes, cave-in eyes and bottom eyes all use Section IV 75ms delay electric detonators, and the peripheral eyes use Section V 100ms delay electric detonators.

[0013] Furthermore, the whole section adopts a small parallel and large series connection method according to the number of detonator sections, that is, the millisecond delay electric detonators of sections Ⅰ to Ⅴ are connected in parallel with the leg wires of the electric detonators with the same number of sections, and then the leg wire strands of different sections are connected in series to form a whole strand. The whole strand is connected to the detonator through the detonating cable, and the detonator energizes each detonator through the wiring network to stimulate ignition.

[0014] Furthermore, the triple wedge straight hole micro-difference blasting is carried out, including: 1) First, for the slot holes with hole numbers 1 to 10, the first section of the explosive body in the hole is cut into a large wedge-shaped slot using a 0ms electric detonator of stage I to form a large wedge; 2) For the slotting holes with hole numbers 11 to 18, the first section of explosive body in the hole and the second section of explosive body in the slotting holes with hole numbers 1 to 10 are two parts, and the second section of 25ms detonator is used for secondary large wedge straight slotting; 3) The second section of explosive body in the slot holes numbered 11 to 18 consists of two parts of explosive body, both of which use the III stage 50ms to form three large wedge straight slot blasting. Among them, the bottom charging part of the 19-20 straight holes and the second section of explosive body in the 11-18 holes jointly throw the primary and secondary broken rocks further out of the slot cavity, and clean up the bulging residual holes formed by the primary and secondary wedges at the bottom to form the final slot cavity.

[0015] Furthermore, a large wedge is formed in the first trenching to form a large trench opening of 1.6 to 2.4 m, and the first trenching provides a free surface of the large trench opening for the second trenching.

[0016] Compared with the prior art, the present invention has the following technical effects: The present invention innovatively proposes a highly efficient multi-directional energy-gathering pre-splitting wedge-shaped slot blasting method for full-section hard rock tunnels, which aims to significantly improve the drilling and blasting efficiency and effect of hard rock tunnels through a series of precisely designed steps. In the specific implementation process, the advanced kilometer-long directional drilling rig technology is first used to accurately complete large-diameter (specifically, the diameter of the explosive is 60 mm, and the corresponding large-diameter borehole diameter is 95 mm) and ultra-deep (depth ranges from 20 meters to 100 meters) drilling operations. The precise execution of this step lays a solid foundation for the subsequent blasting pre-splitting.

[0017] Subsequently, multi-directional energy-focused pre-splitting blasting devices were cleverly installed inside these large-diameter boreholes. The device, through its special design, can pre-splitting the borehole wall with focused energy during blasting, effectively forming an initial crack network. The key to this step is to utilize the energy-focusing effect to efficiently utilize the blasting energy, thereby generating the expected crack structure inside the rock.

[0018] Then, in order to further expand the length and range of these initial cracks, hydraulic fracturing technology is used for secondary fracturing. Hydraulic fracturing injects high-pressure water into the borehole containing the initial cracks, and uses the pressure of water to further expand and connect the cracks, thereby gradually transforming the hard rock in the cut area into relatively loose broken rock mass.

[0019] After completing the above pre-splitting and fracturing steps, a unique multi-wedge straight hole segmented micro-difference slotting method is used next. This method effectively digs out the broken rock mass step by step by finely controlling the blasting time and sequence of different sections, which not only significantly increases the slotting depth, but also optimizes the shape of the slotting cavity, creating more favorable conditions for subsequent blasting operations.

[0020] With the effective increase in the trenching depth and cavity, the subsequent auxiliary eye and peripheral eye blasting operations can be carried out more smoothly, thereby achieving a substantial increase in the overall drilling and blasting excavation footage. Specifically, the trenching method provided by the present invention can increase the existing drilling and blasting excavation footage of hard rock tunnels from the traditional 1.0 to 1.5 meters to 2.8 to 3.2 meters, and the footage efficiency has been significantly improved by more than 250%. This breakthrough has significantly improved the speed and effect of drilling and blasting excavation under hard rock conditions, reaching or approaching the effect level of drilling and blasting excavation in coal seams and soft rock tunnels, and providing a new technical path and solution for the rapid construction of hard rock tunnels. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The main design drawing of a multi-directional energy-gathering pre-splitting wedge-shaped slot blasting method for hard rock tunnels.

[0022] Figure 1 100. Large diameter ultra-deep drilling, 101. The first section of holes 1-5 is charged, 102. The first section of holes 6-10 is charged, 103. The second section of holes 1-5 is charged, 104. The second section of holes 6-10 is charged, 105. The first section of holes 11-14 is charged, 106. The first section of holes 15-18 is charged, 107. The second section of holes 11-14 is charged, 108. The second section of holes 15-18 is charged, 109. The bottom of holes 19-20 is charged.

[0023] Figure 2 Schematic diagram of drilling and blasting, where 100 is a large-diameter ultra-deep borehole, 201 is an auxiliary hole, 202 is a bottom hole, and 203 is a peripheral hole.

[0024] Figure 3 This is a schematic diagram of the trenching area. 100. Large diameter ultra-deep drilling, 301. Hard rock in the trenching area.

[0025] Figure 4 This is a schematic diagram of hydraulic fracturing. 100. Large diameter ultra-deep drilling, 301. Hard rock in the slotting area, and 401. Pre-crack area of ​​multi-directional concentrated energy blasting.

[0026] Figure 5 This is a schematic diagram of the hydraulic fracturing expansion, where 100 is a large-diameter ultra-deep borehole and 501 is a secondary hydraulic fracturing fracture area.

[0027] Figure 6 Schematic diagram of a large slot opening formed by a large wedge in the groove. 100. Large diameter ultra-deep drilling, 601. Cavity after a wedge-shaped groove.

[0028] Figure 7Schematic diagram of secondary groove cavity. 100. Large diameter ultra-deep drilling, 701. Cavity after secondary wedge-shaped groove cutting.

[0029] Figure 8 Schematic diagram of the final slot cavity. 100. Large diameter ultra-deep drilling, 801. Cavity after three wedge-shaped cutting.

[0030] Fig. 9 The invention relates to a buckled large-diameter radiation six-way concentrated energy blasting tube device for coal mines.

[0031] Among them: 1. The upper semicircular tube of the female buckle, 2. The lower semicircular tube of the male buckle, 3. The V-groove gap. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings: See also Figures 1 to 9 The present invention aims at the problems that the actual effect of the existing drilling and blasting slot cutting method in the full-section hard rock lane of coal mine is not ideal after blasting, such as the small actual slot cutting cavity (generally 0.8m-1.2m in width and height), small slot cavity depth (generally 1.1m-1.5m), small single-cycle footage (generally 1.1m-1.5m in single-cycle footage), and extremely low drilling and blasting efficiency. A multi-directional energy-gathering pre-splitting wedge slot cutting blasting method for full-section hard rock lane is proposed. When slotting, the method first uses a kilometer-long directional drilling rig to complete the drilling of large-diameter (explosive diameter 60mm, large-diameter borehole 95mm) ultra-deep holes (20m-100m), and then installs a multi-directional energy-gathering pre-splitting blasting device in the large-diameter borehole to perform energy-gathering blasting pre-splitting and cracking on the borehole wall, and then uses hydraulic fracturing to perform secondary fracturing on the borehole containing cracks to further expand the crack length, thereby converting the hard rock in the slot cutting area into a broken rock mass. After pre-splitting, the multi-wedge straight hole segmented micro-difference slotting method (ZL202010152429.8) is used to dig out the broken rock mass, so as to increase the slotting depth and slotting cavity of the hard rock. As long as the slotting depth and cavity are increased, the subsequent auxiliary eye and peripheral eye blasting can achieve the effect, and finally achieve a significant increase in the drilling and blasting excavation footage. The slotting method provided by the present invention can increase the existing hard rock tunnel drilling and blasting excavation footage of 1.0m~1.5m to 2.8m~3.2m, and the footage efficiency can be increased by more than 250%, so that the drilling and blasting excavation speed and effect under hard rock conditions can reach or approach the level of drilling and blasting excavation effect of coal seam~soft rock tunnel.

[0033] The present invention provides a multi-directional energy-gathering pre-splitting wedge-shaped slot blasting method for hard rock tunnels. This method first uses a kilometer-long drilling rig to drill a directional large-diameter borehole with a diameter of 95 mm and a depth of 30 m to 100 m in the direction of excavation. After the hole is formed, a multi-directional energy-focused blasting device is used to carry out multi-directional energy-focused pre-splitting blasting in the borehole, so that multi-directional energy-focused initial pre-cracks with a length of 300 mm to 500 mm are generated on the borehole wall.

[0034] Then, hydraulic fracturing is used to inject high-pressure water into the borehole. Under the action of high-pressure water fracturing, the initial blasting pre-cracks are further expanded, further breaking the rock mass in the drilling area. Through the dual effects of multi-directional energy pre-cracking and then hydraulic fracturing, the hard rock in the slotting area is transformed into broken and loose rock mass, so as to change the current situation of poor slotting blasting effect caused by hard rock, such as small slotting blasting range and large clamping effect.

[0035] Finally, the multiple wedge straight trenching method is used to dig out the broken rock in the pre-cracked area, so as to increase the trenching depth and trenching cavity of the hard rock. As long as the trenching depth and the cavity are increased, the subsequent auxiliary eye and peripheral eye blasting can achieve the desired effect, and ultimately achieve a significant increase in the drilling and blasting advance.

[0036] The present invention can realize deep hole slot blasting under hard rock conditions, increase the existing drilling and blasting excavation footage of hard rock tunnels from 1.0m to 1.5m to 2.8m to 3.2m, and increase the footage efficiency by more than 250%, so that the excavation speed and effect of the drilling and blasting method under hard rock conditions can reach or approach the level of drilling and blasting excavation effect in coal seam-soft rock tunnels.

[0037] The technical solution adopted by the present invention to solve its technical problem is: Step 1: Drill the large hole.

[0038] Use a kilometer directional drill to drill a hole with a diameter of 95mm-113mm and a length of 30m-100m along the center of the excavation tunnel ( Figure 1 of 100).

[0039] Step 2: Multi-directional concentrated energy blasting pre-splitting.

[0040] A blasting energy focusing device (ZL202010001802.X) for ultra-deep holes, with large diameter, segmented filling, six-way radiation energy focusing, and settable number of cracks is used and loaded with 60mm explosives to achieve multi-directional energy focusing blasting pre-cracking. The energy focusing pre-cracking on the wall of the large hole completed in the first step produces radial pre-cracks. Under hard rock conditions, initial pre-cracks of 300mm to 500mm can be produced along the wall of the large hole.

[0041] The bursting tube device (see Fig. 9) The tube body is hollow cylindrical, with a length of 2m. The diameter of the circle where the inner wall of the tube is located is 63mm. The upper semicircular tube with a female buckle and the lower semicircular tube with a male buckle are buckled together to form a six-way radiation focused blasting tube. The blasting tube has six V-shaped energy-gathering grooves evenly distributed at an angle of 60° along the axial direction of the tube body, distributed around the tube. A linear slit is left at the top corner of each V-shaped energy-gathering groove, and the vertex of the V-shaped energy-gathering groove faces the center of the tube body. The diameter of the circle formed by the vertex of the V-shaped groove is 71mm. The angular bisectors of the V-shaped grooves intersect at one point, and the angle of the V-shaped groove is 60°. The V-shaped groove extends to 20cm from the ends of both ends, but does not penetrate, so as to ensure the overall stability and torsion resistance of the energy-gathering tube. The V-shaped groove is as for the tube wall area, and the inside is cylindrical, which is conducive to the filling of 60mm diameter explosives, which can maximize the use of the space inside the tube and facilitate the formation of six-directional focused jets. A 4mm wide slit is left at the top of the V-shaped groove. The function of the slit is to release the detonation shock wave along the V-shaped groove, impact the rock on the blast hole wall to form initial cracks, and control the number of loose pre-splitting blasting cracks through the six V-shaped grooves set on the pipe. The six-way energy-gathering pipe is connected with the upper semicircular male buckle and the lower semicircular female buckle. The semicircular pipe with male buckle and female buckle is made of specially configured PVC material and special mold.

[0042] When the explosive is loaded into the six-way blasting tube and explodes, the detonation products directly impact the surface of the blasting tube shell at the non-V-shaped slotted guide groove. Because the density of the blasting tube shell is greater than the density of the products on the detonation wave front, and the compressibility of the blasting tube shell is generally less than the compressibility of the detonation products, the detonation products are reflected from the surface and generate reflected shock waves. At the same time, there are also a small number of stress waves that pass through the device wall, but they still need to pass through the annular space between the device and the blasthole wall, and then act on the hole wall, which greatly reduces the direct effect and damage of the detonation products on the hole wall, thereby inhibiting the development of the corresponding blasthole wall cracks between the V-shaped slotted guide grooves, inhibiting the generation of cracks in this area, and achieving the purpose of controlling the number of cracks. At the V-shaped slotted guide groove, the detonation products directly impact the air medium; shock waves are generated therein, forming a concentrated high-speed, high-pressure jet that acts on the blasthole wall in the direction of the V-shaped slotted guide groove, causing ruptures on the blasthole wall, and pre-forming initial cracks. The high-temperature, high-pressure, and high-speed gas generated by the detonation still acts on the hole wall corresponding to the energy-gathering direction first after the stress wave, and flows into the radial initial crack, generating a "gas wedge" effect therein. According to the fracture mechanics theory, when the stress intensity factor at the crack tip exceeds the fracture toughness of the rock, the crack becomes unstable and drives the crack to expand. This continuously provides new free surfaces for subsequent compression stress waves. The compression stress wave is transformed into a tensile wave by reflection from the free surface; therefore, tensile stress concentration is generated in the direction of vertical crack expansion, accelerating crack expansion, and the rock mass is stretched and cracked along the set direction, thereby increasing the crack length in the pre-set six directions.

[0043] Step 3: Hydraulic fracturing.

[0044] First, in the large hole after multi-directional focused blasting ( Figure 4 In 100), the packer is pressurized to expand the rubber tube and seal the large hole. Then, a high-pressure hose is connected to a high-pressure pump to inject high-pressure water into the sealed large hole. Under the action of high-pressure water, the multi-directional energy-gathering pre-cracks are squeezed and torn by monitoring the water pressure. The initial crack length produced by the multi-directional energy-gathering blasting ranges from 300mm to 500mm ( Figure 4 401) expanded to 3000~4000mm( Figure 5 501), so that the rock in the central area is composed of hard and complete rock ( Figure 4 301) into broken and fractured rock mass ( Figure 5 501) to reduce the impact of hard rock on the slot blasting effect.

[0045] Step 4: Drilling and blasting.

[0046] 1) Use a rock drilling rig to drill holes in the pre-splitting and crushing area. The rock drilling rig has an arm length of 4.7m, a drill rod length of 3.5m, a maximum effective drilling depth of 3.2m, a drilling diameter of 42mm, and is suitable for rock tunnel section width x length of 5.2 to 7.0m. Figure 2 As shown, drilling is carried out, among which the slot holes (hole numbers 1 to 10) have a hole depth of 2.0 to 2.4 m, and the angle between the oblique hole and the tunnel face is 55 to 75°; the slot holes (hole numbers 11 to 18) have a hole depth of 3.2 m, and the angle between the oblique hole and the tunnel face is 75 to 85°; the center slot holes (hole numbers 19 to 10) use 90° straight holes.

[0047] 2) Then set peripheral holes at different intervals around the tunnel contour according to the lithology and soft rock, and arrange auxiliary holes as needed in the area inside the peripheral holes and outside the groove hole area ( Figure 2 201), peripheral eyes ( Figure 2 Middle 203), bottom eye ( Figure 2 202).

[0048] Step 5: Loading.

[0049] To the slot holes (hole numbers 1-20), auxiliary holes ( Figure 2 Middle 201), bottom eye ( Figure 2 202), peripheral eyes ( Figure 2 203) to fill the hole with explosives, and complete the full-section explosive filling. The patent of this invention focuses on the charging steps and charging structure of the slot hole: 1) First, the groove holes (hole numbers 1-10) are divided into two sections (see Figure 1 As shown in Figure 2), the bottom charge section is the second section in the hole (see Figure 2). Figure 1 Zhong 103 and Figure 1 104), loaded with 32mm diameter, 400mm long third-grade water gel explosive, the length of the charge accounts for 20% to 25% of the hole length, using a 25ms delay electric detonator with a foot line and a detonating cord with the same length as the charge at the bottom of the hole; after filling the charge at the bottom of the hole, then plug it with yellow mud to block the charge at the bottom of the hole, with a length of 500mm; then fill the first section in the hole (see Figure 1 Zhong 101 and Figure 1 In 102), the first section of the explosive body uses a 32mm diameter, 400mm long third-grade water-gel explosive, the length of which accounts for 25% to 30% of the hole length. A 0ms delay electric detonator with a leg line and a detonating cord of the same length as the second section of the charge are used; then the hole is filled with yellow mud to seal the hole. The length of the yellow mud sealing is not less than 0.5m, and the sealing length is generally 0.6m to 1.0m.

[0050] 2) Then the groove holes (hole numbers 11-18) are divided into two sections in each hole (see Figure 1 As shown in Figure 2), the bottom charge section is the second section in the hole (see Figure 2). Figure 1 Zhong 107 and Figure 1 108), loaded with 32mm diameter, 400mm long third-grade water gel explosive, the length of the charge accounts for 20% to 25% of the hole length, using a Ⅲ-stage 50ms delay electric detonator with a foot line and a detonating cord with the same length as the charge at the bottom of the hole; after filling the charge at the bottom of the hole, then plug it with yellow mud to block the charge at the bottom of the hole, with a length of 500mm; then fill the first section in the hole (see Figure 1 Zhong 105 and Figure 1 In 106), the first section of the explosive body uses a 32mm diameter, 400mm long third-grade water-gel explosive, the length of which accounts for 25% to 30% of the hole length. A 25ms delay electric detonator with a leg line and a detonating cord of the same length as the second section of the charge are used; then the hole is filled with yellow mud to seal the hole. The length of the yellow mud sealing is not less than 0.5m, and the sealing length is generally 0.6m to 1.0m.

[0051] 3) Then cut the groove hole (hole number 19-20) at the bottom of the hole ( Figure 1 In No. 109, 1 to 2 sections of 32mm diameter and 400mm long third-grade water-gel explosive are loaded. The drill hole diameter is 42mm. The explosives are 32mm diameter and 400mm long third-grade water-gel explosives. The uncoupling coefficient is 1.31. A single hole is detonated by a foot wire with a III-stage 50ms delay electric detonator. The charge is loaded in the forward direction and the hole is sealed with yellow mud. The sealing length is not less than 0.3m.

[0052] After the charging of the groove eyes is completed, the auxiliary eyes, cave-in eyes, bottom eyes and peripheral eyes are filled according to the design requirements of normal smooth blasting or concentrated energy smooth blasting. Among them, the auxiliary eyes, cave-in eyes and bottom eyes all use Section IV 75ms delay electric detonators, and the peripheral eyes use Section V 100ms delay electric detonators.

[0053] Step 6: Connect the wires.

[0054] The entire section adopts a small parallel and large series connection method according to the number of detonator sections, that is, the millisecond delay electric detonators of sections Ⅰ to Ⅴ are connected in parallel into one strand, and then the leg wires of different sections are connected in series to form a whole strand. The whole strand is connected to the detonator through the detonating cable, and the detonator energizes and ignites each detonator through the wiring network, and then detonates the explosives in each hole.

[0055] Step 7: Blasting.

[0056] During blasting, the following blasting sequence and method shall be followed: 1) First, the first section of explosive body in the slot hole (hole number 1 to 10) Figure 1 101 and Figure 1 102) Use 0ms electric detonator of stage I to dig a large wedge (i.e. 1 to 10 constitute a large wedge), and a large wedge in a groove forms a 1.6 to 2.4m large groove opening ( Figure 6 601), reducing the deep clamping effect of the lower eyelet, that is, a single cut (see Figure 6 601) provides a large slot opening free surface for the secondary slotting and reduces the deep clamping effect of the secondary slotting eye.

[0057] 2) Then, the first section of explosive body in the slot hole (hole number 11 to 18) Figure 1 105 and Figure 1 106) and the second section of explosives in the holes with positions 1 to 10 in the cutout holes ( Figure 1 103 and Figure 1 104) consists of two parts, using the Ⅱ stage 25ms detonator to carry out the secondary large wedge straight trenching (i.e. the first stage of explosive body in holes 11 to 18 ( Figure 1 105 and Figure 1 106) and the second section of explosives in holes 1 to 10 ( Figure 1 103 and Figure 1 104) together form a secondary large wedge), where the large empty hole 0 straight eye empty hole part has the function of providing a free surface for the secondary large wedge oblique eye along the axial depth of the roadway. The secondary large wedge and the secondary empty hole straight eye further expand the groove cavity to form a secondary groove cavity (see Figure 7 (701).

[0058] 3) Then, the second section of explosive body in the hole number 11 to 18 in the slot hole ( Figure 1 107 and Figure 1 108), the bottom charge part of hole number 19 to 20 ( Figure 1 109), a total of two parts of explosive bodies, both use the III section 50ms to form three large wedge straight groove blasting, (hole number 19 to 20 straight hole bottom charging part, 11 to 18 holes in the first section of the explosive body together to form three large wedge straight groove) blasting. Among them, the 19 to 20 straight hole bottom charging part ( Figure 1 109) and the second section of explosive body in holes 11 to 18 ( Figure 1 107 and Figure 1 108) can jointly throw the primary and secondary crushed rocks further out of the slot cavity, thus clearing the slot cavity to provide a free surface for auxiliary, caving and bottom hole blasting. At the same time, it can fully clean the bulging residual holes formed by the primary and secondary wedges at the bottom, deepen the bottom of the slot cavity to a hole depth of 3m, and form the final slot cavity (see Figure 8 (in Chinese: 801).

[0059] The key features of the patented method of the present invention during the blasting process also include the following five points: ① Use a blasting energy-gathering device for ultra-deep holes with large diameter, segmented filling, six-way radiation energy-gathering, and settable number of cracks (ZL202010001802.X) and load 60mm explosives to achieve multi-directional energy-gathering blasting pre-cracking. The energy-gathering pre-cracking on the large hole wall completed in the first step produces radial pre-cracks. Under hard rock conditions, initial pre-cracks of 300mm to 500mm can be produced along the large hole wall.

[0060] ② Because the excavation footage of broken rock mass is much larger than that of hard rock, the present invention proposes to first use a kilometer-long drilling rig to drill an ultra-deep large-diameter borehole with a diameter of 95mm-113mm and a depth of 30m-100m along the center of the tunnel excavation direction; then use multi-directional concentrated energy blasting in the hole to generate 300-500mm radial initial cracks along the periphery of the hole wall; then use the packer to pressurize the rubber cylinder to expand the large hole mouth, and then use a high-pressure hose to connect the high-pressure pump to inject high-pressure water into the sealed large hole. Under the action of high-pressure water, the multi-directional concentrated energy pre-cracks are squeezed and torn by monitoring the water pressure. The length of the initial cracks generated by the multi-directional concentrated energy blasting is expanded from 300mm-500mm to 2000-3000mm, so that the rock in the central area is transformed from hard and intact rock to broken and fractured rock mass, thereby achieving the purpose of increasing the excavation footage in hard rock.

[0061] ③ The patent feature of the present invention is that when the initial cracks are created by the multi-energy concentrated blasting of high-pressure water fracturing, the expansion radius d2 of the water pressure crack is made larger than the size a of the groove area by monitoring and controlling the water pressure, so as to ensure that the groove area is located in the pre-cracking area and convert the hard rock in the groove area into broken rock mass; at the same time, the expansion radius d2 is smaller than the tunnel excavation diameter x, so as to ensure that the pre-cracking range does not exceed the rock within the tunnel excavation range, and does not damage the surrounding rock of the tunnel after the tunnel excavation, so that the surrounding rock of the tunnel excavation remains hard to play a supporting role.

[0062] ④ The empty holes formed by the ultra-deep large-diameter drilling holes with a diameter of 95mm-113mm and a depth of 30-100m completed by the kilometer-long drilling rig provide a central large-diameter hole free surface for the first slotting of the first section of the explosive body in the slotting eye (hole number 1-10), which can improve the effect of the first slotting; at the same time, the residual large-diameter empty holes provide a central large-diameter hole free surface for the second slotting of the first section of the explosive body in the slotting eye (hole number 11-18) and the second section of the explosive body in the slotting eye (hole number 1-10), which can improve the effect of the second slotting.

[0063] ⑤ One of the characteristics of the present invention compared with the general wedge-straight mixed slotting is that the slotting blasting is carried out by triple wedge-straight blasting, step-by-step deepening and step-by-step expansion of the slot cavity, forming an opening cavity with a width of 1.6 to 2.8 m and a height of 1.2 to 1.6 m; the slot cavity bottom is 0.9 to 1.5 m wide and 1.9 to 1.2 m high, and is a flat rectangular slot cavity. This type of slot cavity is conducive to the collapse of the upper semicircular arch and part of the bottom plate rock. This three-step progressive slotting and synchronous slot cavity expansion method completes the slotting. The previous slotting provides a large free surface for the next slotting, improves the slotting effect and reduces the clamping effect of deep rocks. The specific method is: Firstly, the first section of explosive body in the grooved hole (hole number 1 to 10) cooperates with the large diameter central hole to complete the first wedge-shaped groove to form a 1.6 to 2.4 m large groove cavity opening, provide a large groove opening cavity free surface for the secondary groove, and reduce the deep clamping effect of the secondary grooved hole.

[0064] Then, the first section of the explosive body in the grooved holes (hole numbers 11 to 18) and the second section of the explosive body in the holes with numbers 1 to 10 in the grooved holes are combined into two parts, and the large empty hole straight eye empty hole part is cooperated to complete the second large wedge-shaped oblique eye grooved, further expanding the groove cavity to form a secondary groove cavity, providing a large free surface for the third grooved.

[0065] 3) Then, the second section of explosives in the holes with positions 11 to 18 and the bottom charge part of the holes with positions 19 to 20, a total of two parts of explosives, constitute three large wedge straight slot blasting. Among them, the bottom charge part of the straight holes 19 to 20 and the second section of explosives in the holes 11 to 18 can jointly throw the primary and secondary broken rocks out of the slot cavity, which can clear the slot cavity to provide a free surface for auxiliary, collapse hole and bottom hole blasting, and at the same time, it can fully clean the bulging residual holes formed by the primary and secondary wedges at the bottom, deepen the bottom of the slot cavity to a hole depth of 3m, and form the final slot cavity.

[0066] The invention provides a deep hole trenching method for a hard rock tunnel, which comprises the following steps: a kilometer-long drilling rig is used to drill an ultra-deep large-diameter borehole with a diameter of 95mm-113mm and a depth of 30m-100m in the center of the tunnel excavation direction; then, multi-directional concentrated energy blasting is used in the hole to generate 300-500mm radial initial cracks along the periphery of the hole wall; then, a packer is pressurized to expand a rubber cylinder to seal the large hole mouth; then, a high-pressure hose is used to connect a high-pressure pump to inject high-pressure water into the sealed large hole; under the action of high-pressure water, the multi-directional concentrated energy pre-cracks are squeezed and torn by monitoring the water pressure, and the length of the initial cracks generated by the multi-directional concentrated energy blasting is expanded from 300mm-500mm to 2000-3000mm, so that the rock in the central position area is transformed from hard and complete rock to broken and fractured rock mass, thereby achieving the purpose of increasing the trenching footage in the hard rock. Then, the triple wedge straight hole is used for micro-difference blasting, step-by-step deepening and step-by-step expansion of the slot cavity, forming an opening cavity with a width of 1.6 to 2.8 m and a height of 1.2 to 1.6 m; the slot cavity bottom is 0.9 m to 1.5 m wide and 1.9 m to 1.2 m high, and is a flat rectangular slot cavity. This slot cavity is conducive to the collapse of the upper semicircular arch and part of the bottom plate, and can achieve the effect of more than 3.0 m of slotting depth, high single-cycle footage, reduced large-block waste rock rate, and shortened waste rock throwing distance. It can also provide a free surface for the blasting of the second-step auxiliary eye, collapse eye, and bottom eye, ensuring that the auxiliary eye, collapse eye, and bottom eye can be fully blasted and also reach a depth of 3 meters, and further ensure that the blasting depth of the surrounding eyes also reaches 3 meters. This method is suitable for rock tunnels with a cross-sectional width of 4.2 to 7.5 m.

[0067] Example: In the 8-1 mining area of ​​Qianyingzi Coal Mine of Wanbei Coal and Electricity, the transport tunnel is designed to be 1300m long and the starting and ending elevations are –620~–850.0m. The transport tunnel adopts a straight wall semi-circular arch shape, anchor mesh cable spraying support, gross section width 5240mm, gross section height 4120mm, net section width 5100mm, net section height 4050mm. The surrounding rock is white sandstone, complete, with a hardness coefficient of f=10~13, which belongs to the hard sandstone layer.

[0068] The original construction plan adopted the drilling and blasting method. The specific method was to drill blasting holes in the entire section of the transport level tunnel at one time and blast in groups. The group blasting used two groups of explosives, and each group was detonated once, that is, the first charge blasted the range of 1.2m above the bottom plate, and the second charge blasted the range of 1.2m from the bottom plate to the top of the tunnel. 126 holes were drilled in the entire section, including 76 holes for the first blasting and 50 holes for the second blasting. After blasting, the single cycle advance was 2.5 to 2.6m. The tunnel was poorly formed. Because of the development of surrounding rock joints and bedding, there was a serious over-excavation phenomenon with unevenness. It was necessary to adopt initial spraying when supporting the tunnel. The initial spraying volume increased the cost of 260 yuan per meter due to the over-excavation phenomenon. The under-excavated part required a large number of manual secondary expansion and repair sections, otherwise it was difficult to ensure the section size. The part that was difficult to expand and repair required manual blasting holes for three blastings, which caused great difficulties for tunnel excavation. In addition, after each blasting, the gangue is thrown 45m away, causing the drill rig to move back 50m, increasing the equipment movement time, reducing drilling efficiency, and affecting the excavation speed. The thrown gangue is large in size, with a single block volume of 1.0*1.2*1.2m accounting for 20% to 35%, and underground transportation requires that the size of the gangue block cannot exceed 40cm, otherwise it is difficult to pass through the gangue hole, so it takes a lot of manpower and time to use a pneumatic pick to break the large gangue into small pieces, increasing construction costs and manpower investment. The construction adopts a 38 system, with an overall single-cycle advance of 1.5 to 2.0m, three cycles in two days, an average daily advance of 2.25m to 3m, and a monthly advance of 65m to 90m. The excavation speed is slow, resulting in tight succession in the mining area and the inability to carry out production as scheduled.

[0069] The new scheme adopts the patented multi-directional energy-gathering pre-splitting wedge-shaped slot blasting method for hard rock tunnels. Based on this, the drilling and blasting parameters and construction process are designed. The test results show that the single slotting depth is maintained at 2.85-3.0m, and there is no obvious large piece of gangue after blasting, which meets the underground transportation requirements. The maximum distance of throwing gangue is 35m, and the average is 25-30m, which greatly reduces the backward movement distance of the drilling equipment and saves a lot of equipment moving time and engineering. The construction organization and management of the four-six-shift small-shift cycle greatly improves the excavation efficiency. The single-cycle footage is 2.8-3.0m, two days and three cycles, and the average daily footage is 4.2m-4.5m. The monthly footage is maintained at 125m-145m, which is 161%-223% higher than the original. The cost of single-meter tunnel footage is reduced by 1,146 yuan.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A multi-directional energy-gathering pre-splitting and multi-wedge straight slot blasting method for hard rock tunnels, characterized in that: include: Directional drilling is performed in the excavation direction. After the hole is formed, a multi-directional concentrated energy blasting device is used in the borehole for multi-directional concentrated energy pre-crack blasting, so that multi-directional concentrated energy initial pre-cracks are generated on the borehole wall; Implement high-pressure water injection into the borehole after multi-directional energy-gathering pre-splitting blasting to further expand the multi-directional energy-gathering initial pre-cracks; The multi-wedge straight trenching method is used to dig out the broken rock mass in the multi-directional energy-gathering initial pre-crack area to obtain a large-sized trench cavity.

2. A multi-directional energy-gathering pre-splitting and multi-wedge straight slot blasting method for hard rock tunnels according to claim 1, characterized in that: Directional drilling in the direction of excavation, including: A kilometer-long directional drill is used to drill a hole with a diameter of 95mm-113mm and a length of 30m-100m along the center of the excavation tunnel.

3. A multi-directional energy-gathering pre-splitting and multi-wedge straight slot blasting method for hard rock tunnels according to claim 1, characterized in that: After the hole is formed, a multi-directional concentrated energy blasting device is used in the borehole to perform multi-directional concentrated energy pre-crack blasting, so that multi-directional concentrated energy initial pre-cracks are generated on the borehole wall, including: A blasting energy focusing device for ultra-deep holes, with large diameter, segmented filling, six-way radiation energy focusing, and adjustable crack number is used to load explosives for multi-directional energy focusing blasting pre-cracking, which produces radial pre-cracks on the borehole wall.

4. A multi-directional energy-gathering pre-splitting and multi-wedge straight-cutting blasting method for hard rock tunnels according to claim 1, characterized in that: Implement high-pressure water injection in the borehole after multi-directional energy-gathering pre-splitting blasting, including: In the borehole after the multi-directional energy pre-splitting blasting, the packer is pressurized to expand the rubber tube and seal the large hole. Then, a high-pressure hose is used to connect the high-pressure pump to inject high-pressure water into the sealed large hole. Under the action of high-pressure water, the multi-directional energy pre-cracks are squeezed and torn by monitoring the water pressure. The initial crack length generated by the multi-directional energy blasting is expanded from 300mm to 500mm to 3000 to 4000mm, so that the rock in the central area is transformed from hard and intact rock to broken and fractured rock mass.

5. A multi-directional energy-gathering pre-splitting and multi-wedge straight-cutting blasting method for hard rock tunnels according to claim 1, characterized in that: The multi-wedge straight trenching method is used to dig out the broken rock mass in the multi-directional energy-gathering initial pre-crack area to obtain a large-sized trench cavity, including: Drill holes in the pre-splitting and crushing area, then set peripheral holes with different spacings around the tunnel contour according to the soft rock lithology, and arrange auxiliary holes, peripheral holes and bottom holes in the area inside the peripheral holes and outside the groove hole area; Explosives are loaded into the slot holes, auxiliary holes, bottom holes and peripheral holes respectively, and micro-difference multiple blasting is carried out in the triple wedge straight holes.

6. A multi-directional energy-gathering pre-splitting and multi-wedge straight slot blasting method for hard rock tunnels according to claim 5, characterized in that: Slot holes are drilled in the pre-splitting and crushing zone, including: using a rock drilling rig to drill slot holes in the pre-splitting and crushing zone, wherein the slot holes with hole numbers 1 to 10 have a hole depth of 2.0 to 2.4 m, and an angle between the oblique hole and the tunnel face of 55 to 75°; the slot holes with hole numbers 11 to 18 have a hole depth of 3.2 m, and an angle between the oblique hole and the tunnel face of 75 to 85°; the central slot holes with hole numbers 19 to 10 use 90° straight holes.

7. A multi-directional energy-gathering pre-splitting and multi-wedge straight-cutting blasting method for hard rock tunnels according to claim 5, characterized in that: Filling explosives into the cut holes, auxiliary holes, bottom holes, and peripheral holes respectively, including: 1) For the slotted holes with hole numbers 1-10, each hole is divided into two sections, of which the bottom charge part is the second section in the hole, which is loaded with a 32mm diameter and 400mm long third-grade water-gel explosive, and the charge length accounts for 20% to 25% of the hole length. A 25ms delay electric detonator with a leg line and a detonating cord with the same length as the bottom charge are used; after the bottom charge is loaded, yellow mud is then stuffed to block the bottom charge part of the hole, and the blocking length is 500mm; then the first section in the hole is loaded, and the first section of the explosive body uses a 32mm diameter and 400mm long third-grade water-gel explosive, and the charge length accounts for 25% to 30% of the hole length. A 0ms delay electric detonator with a leg line and a detonating cord with the same length as the second section of the charge are used; then the hole is filled with yellow mud to seal the hole, and the yellow mud plugging filling length is not less than 0.5m, and the plugging length is 0.6m to 1.0m; 2) For the slotted holes with hole numbers 11-18, each hole is divided into two sections, of which the bottom charge part is the second section in the hole, which is loaded with 32mm diameter and 400mm long third-grade water-gel explosive, the length of which accounts for 20% to 25% of the hole length, and a Ⅲ-section 50ms time-delay electric detonator with a leg line and a detonating cord with the same length as the bottom charge of the hole are used; after the bottom charge part of the hole is filled, yellow mud is then stuffed to block the bottom charge part of the hole, with a blocking length of 500mm; then the first section in the hole is filled, and the first section of the explosive body uses a 32mm diameter and 400mm long third-grade water-gel explosive, the length of which accounts for 25% to 30% of the hole length, and a Ⅱ-section 25ms time-delay electric detonator with a leg line and a detonating cord with the same length as the second section of the charge are used; then the hole is sealed with yellow mud, and the length of the yellow mud plugging is not less than 0.5m, and the plugging length is 0.6m to 1.0m; 3) For the cutout holes with hole numbers 19-20, 1-2 sections of 32mm diameter and 400mm length three-grade water-gel explosives are placed at the bottom of the holes. The diameter of the drill hole is 42mm. The explosives are 32mm diameter and 400mm length three-grade water-gel explosives with an uncoupling coefficient of 1.

31. The single hole is detonated by a foot line with a 50ms delay electric detonator of stage III. The charge is loaded forward and the hole is sealed with yellow mud. The length of the sealed hole is not less than 0.3m. After the charging of the groove eyes is completed, the auxiliary eyes, cave-in eyes, bottom eyes and peripheral eyes are filled according to the design requirements of normal smooth blasting or concentrated energy smooth blasting. Among them, the auxiliary eyes, cave-in eyes and bottom eyes all use Section IV 75ms delay electric detonators, and the peripheral eyes use Section V 100ms delay electric detonators.

8. A multi-directional energy-gathering pre-splitting and multi-wedge straight-cutting blasting method for hard rock tunnels according to claim 7, characterized in that: The entire section adopts a small parallel and large series connection method according to the number of detonator sections, that is, the millisecond delay electric detonators of sections Ⅰ to Ⅴ are connected in parallel. The hole leg lines of the electric detonators with the same number of sections are connected in series into one strand, and then the leg line strands of different sections are connected in series to form a whole strand. The whole strand is connected to the detonator through the detonating cable, and the detonator energizes each detonator through the wiring network to stimulate ignition.

9. A multi-directional energy-gathering pre-splitting and multi-wedge straight slot blasting method for hard rock tunnels according to claim 5, characterized in that: Conduct triple wedge straight hole micro-difference blasting, including: 1) First, for the slot holes with hole numbers 1 to 10, the first section of the explosive body in the hole is cut into a large wedge-shaped slot using a 0ms electric detonator of stage I to form a large wedge; 2) For the slotting holes with hole numbers 11 to 18, the first section of explosive body in the hole and the second section of explosive body in the slotting holes with hole numbers 1 to 10 are two parts, and the second section of 25ms detonator is used for secondary large wedge straight slotting; 3) The second section of explosive body in the slot holes numbered 11 to 18 consists of two parts of explosive body, both of which use the III stage 50ms to form three large wedge straight slot blasting. Among them, the bottom charging part of the 19-20 straight holes and the second section of explosive body in the 11-18 holes jointly throw the primary and secondary broken rocks further out of the slot cavity, and clean up the bulging residual holes formed by the primary and secondary wedges at the bottom to form the final slot cavity.

10. A multi-directional energy-gathering pre-splitting and multi-wedge straight-cutting blasting method for hard rock tunnels according to claim 9, characterized in that: A large wedge in the first trenching forms a large trench opening of 1.6 to 2.4 m. The first trenching provides a free surface for the large trench opening for the second trenching.

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