Blasthole arrangement structure and blasting method for working face of hard rock tunnel with medium and small sections

Abstract

The invention discloses a small and medium section hard rock tunnel working face blasthole arrangement structure and a blasting method, and relates to the technical field of tunnel excavation, the small and medium section hard rock tunnel working face blasthole arrangement structure comprises a working face and blastholes, the blastholes comprise a first slotting oblique hole, a second slotting oblique hole, a first slotting straight hole, a second slotting straight hole, a slot expanding hole, an auxiliary hole, a peripheral hole and a bottom hole; the blastholes can be filled with explosives and plugging devices; the working surface is bilaterally symmetrical about the first central surface; all the first slotting oblique holes are sequentially arranged in the longitudinal direction, and all the first slotting oblique holes are gradually close to the first center face from the working face to the fundus of the first slotting oblique holes; the second slotting inclined hole and the first slotting inclined hole are arranged in bilateral symmetry about the first central plane; a first slotting straight hole is formed between any two adjacent first slotting inclined holes, and a second slotting straight hole is formed between any two adjacent second slotting inclined holes; the cutting effect can be effectively improved, and the cutting efficiency and the tunnel excavation efficiency are improved.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel excavation, and in particular to a blasthole arrangement structure and a blasting method for a working face of a hard rock tunnel with a small or medium section. Background Art

[0002] The heading face, also known as the tunnel face, is a term used in tunnel construction, which refers to the working face that continuously advances forward during tunnel excavation (in coal mining, mining or tunnel engineering).

[0003] Cutting, also known as slotting holes, is used in tunnel excavation. The cutting holes are arranged at a lower position in the center of the face. The cutting holes are detonated first to throw out the central rock, increase the free surface for the surrounding rock, and achieve the best blasting effect. First, a part of the rock on the working face is broken down to form a second free surface on the working face, creating favorable conditions for the blasting of other blastholes. The quality of the cutting plays a decisive role in improving the rock breaking efficiency and the cycle footage.

[0004] The effect of slot blasting, also known as slot hole blasting, is a key link in whether the full-section blasting of the tunnel can achieve the expected effect. Its purpose is to provide a new free surface for the full-section blasting. The main task of tunneling blasting is to blast the rock mass down according to the specified section at a high speed and high quality under the condition of ensuring safety, and to minimize the damage to the shaft or tunnel surrounding rock. To this end, it is necessary to reasonably arrange a certain number of blastholes on the working face, load an appropriate amount of explosives, and then blast.

[0005] In the blasting of hard rock tunnels with small and medium sections (cross-sectional area ranging from 50 square meters to 100 square meters), the diamond straight-eye cutting method is often used, which has poor cutting effect, low cutting efficiency and low tunnel excavation efficiency. Summary of the invention

[0006] The purpose of the present invention is to provide a blasthole arrangement structure and blasting method for the working face of a hard rock tunnel with a small or medium section, so as to solve the problems existing in the above-mentioned prior art, and to effectively improve the trenching effect, trenching efficiency and tunnel excavation efficiency.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides a blasthole arrangement structure for a working face of a hard rock tunnel with a small or medium section, comprising a working face and blastholes, wherein the blastholes comprise a plurality of first slotted oblique eyes, a plurality of second slotted oblique eyes, a plurality of first slotted straight eyes, a plurality of second slotted straight eyes, a plurality of expanded slot eyes, a plurality of auxiliary eyes, a plurality of peripheral eyes and a plurality of bottom eyes; the blastholes can be filled with explosives and pluggers, and the pluggers can plug the blastholes; the working face is bilaterally symmetrical about a first center plane; the first slotted oblique eyes are arranged in sequence in the longitudinal direction, the distances from the eye openings of the first slotted oblique eyes to the first center plane are equal, and the first slotted eyes gradually approach the first center plane from the working face to the eye bottom of the first slotted oblique eyes; the number of the second slotted oblique eyes is equal to the number of the first slotted oblique eyes, and the second slotted oblique eyes are arranged at the same distance from the working face to the eye bottom of the first slotted oblique eyes; the number of the second slotted oblique eyes is equal to the number of the first slotted oblique eyes, and the second slotted eyes are arranged at the same distance from the working face to the eye bottom of the first slotted oblique eyes. The first grooved oblique eyes correspond to each other one by one, and the second grooved oblique eyes are symmetrically arranged with the first grooved oblique eyes about the first center plane; one first grooved straight eye is arranged between any two adjacent first grooved oblique eyes, and one second grooved straight eye is arranged between any two adjacent second grooved oblique eyes, and each second grooved straight eye is symmetrical with each first grooved straight eye about the first center plane; each expanded groove eye is arranged above the first grooved oblique eye and the second grooved oblique eye; each auxiliary eye is arranged on the outside of the first grooved oblique eye, the second grooved oblique eye and the expanded groove eye; each bottom eye is arranged below the first grooved oblique eye and the second grooved oblique eye; each peripheral eye is arranged on the outside of the auxiliary eye, and each peripheral eye and each bottom eye form a circle.

[0009] Preferably, the number of the first cutout oblique eyes is four.

[0010] Preferably, a leak-proof area is left between the fundus of the second cutout oblique eye and the fundus of the first cutout oblique eye, and the width of the leak-proof area is 200 mm to 600 mm.

[0011] Preferably, the diameter of the blastholes is 40 mm.

[0012] Preferably, the distance from the opening of the first cutout oblique eye to the first center plane is 1000 mm to 1500 mm, and the distance between any two adjacent first cutout oblique eyes is 800 mm to 1000 mm.

[0013] Preferably, each of the auxiliary eyes is divided into at least two auxiliary eye layers from the inside to the outside, the distance between any two adjacent auxiliary eyes in the same layer is 900mm~1100mm, the distance between any two adjacent auxiliary eye layers is 1000mm~1500mm, the distance from the eye mouth of the first grooved oblique eye to the innermost auxiliary eye layer is 1000mm~1500mm, the peripheral eye forms a peripheral eye layer, the distance from the peripheral eye layer to the outermost auxiliary eye layer is 600mm~900mm, and the distance between any two adjacent peripheral eyes is 450mm~600mm.

[0014] Preferably, the projection distance between the eye mouth of the first groove oblique eye and the eye bottom of the first groove oblique eye on the first center plane is equal to the depth of the first groove straight eye and the depth of the bottom eye, and the depth of the first groove straight eye is greater than the depths of the auxiliary eye, the peripheral eye and the expanded groove eye.

[0015] Preferably, the depth of the first straight groove eye is 4000 mm to 4200 mm, and the depths of the auxiliary eye, the peripheral eye and the expanded groove eye are all 3700 mm to 3800 mm.

[0016] Preferably, the plugging device includes a gun plug and gun mud, and the gun plug and the gun mud are alternately arranged in the blasthole.

[0017] The present invention also provides a blasting method, using the blasthole arrangement structure for the working face of a hard rock tunnel with a small or medium cross section as described above, comprising the following steps:

[0018] Step 1: punch the first slotting oblique eye, the second slotting oblique eye, the first slotting straight eye, the second slotting straight eye, the expanded slot eye, the auxiliary eye, the peripheral eye and the bottom eye on the working surface;

[0019] Step 2: Filling explosives into the first slotted oblique eye, the second slotted oblique eye, the first slotted straight eye, the second slotted straight eye, the expanded slot eye, the auxiliary eye, the peripheral eye and the bottom eye, and then installing the plugging device;

[0020] Step 3: detonating the explosives in the first cutout oblique eye and the second cutout oblique eye;

[0021] Step 4: detonating the explosives in the first cutout straight eye and the second cutout straight eye;

[0022] Step 5: Detonating the explosives in the expanded slot;

[0023] Step 6: Detonate the explosives in the auxiliary eyes;

[0024] Step 7: Detonate the explosives in the surrounding eyes;

[0025] Step 8: Detonate the explosives in the bottom eye.

[0026] Compared with the prior art, the present invention has achieved the following technical effects:

[0027] The blasthole arrangement structure and blasting method for the working face of a small and medium-section hard rock tunnel provided by the present invention are as follows: by arranging a first slotted oblique eye and a second slotted oblique eye on the working face, and arranging each of the first slotted oblique eyes in sequence in the longitudinal direction, the distances from the mouths of each of the first slotted oblique eyes to the first central plane are equal, each of the first slotted oblique eyes gradually approaches the first central plane from the working face to the bottom of the eye of the first slotted oblique eye, and the second slotted oblique eye and the first slotted oblique eye are arranged symmetrically with respect to the first central plane, so that after the first slotted oblique eye and the second slotted oblique eye are filled with explosives and detonated, the rocks in the areas surrounded by each of the first slotted oblique eyes and the second slotted oblique eyes can be thrown out, and a blasting hole can be obtained on the rock mass. The terrace-shaped slot cavity is designed to have a unique slot blasting mechanism, that is, the first slotting straight eye and the second slotting straight eye are first blasted out with explosives, and then the first slotting straight eye and the second slotting straight eye are used to dig the slot, which can ensure that the first slotting oblique eye, the second slotting oblique eye, the first slotting straight eye and the second slotting straight eye are composite slotting blasting structures for hard rock tunnels with small and medium sections. The first slotting oblique eye and the second slotting oblique eye are first used to blast out the terrace-shaped slot cavity, and then the first slotting straight eye and the second slotting straight eye are used to dig the slot, which can ensure that the first slotting oblique eye and the second slotting straight eye are composite slotting blasting structures for hard rock tunnels with small and medium sections. The gathering of blasting energy at the bottom of the second slotting oblique eye, the first slotting straight eye and the second slotting straight eye can ensure the range of hard rock crushing at the bottom of the first slotting oblique eye, the second slotting oblique eye, the first slotting straight eye and the second slotting straight eye, blast out the bottom slot cavity and improve the overall slotting effect. In addition, the blocking effect of the plugger prolongs the explosion time of the fundus of the first slotting straight eye and the second slotting straight eye, fully crushes the fundus rock and ensures that the bottom slot cavity can collapse. Combined with the unique composite slotting structure, it can not only effectively avoid the "pulling tube" phenomenon, but also effectively increase the slotting blasting depth, creating good conditions for auxiliary eye blasting and innovating the slotting method. , improve the slotting blasting effect, thereby improving the blasting footage and light blasting quality, speeding up the excavation construction speed, shortening the construction period, changing the negative view of Party A, and reducing costs; after the slotting is completed, the expanded slot eyes, auxiliary eyes, peripheral eyes and bottom eyes are gradually filled with explosives and detonated to achieve full-section blasting. Among them, filling the expanded slot eyes with explosives and detonating them can expand the above rectangular slot cavity upward toward the tunnel arch direction, filling the auxiliary eyes with explosives and detonating them can further expand the above rectangular slot cavity from the inside to the outside on the basis of expanding upward toward the tunnel arch direction, and filling the peripheral eyes and bottom eyes with explosives and detonating them can control the forming contour of the tunnel section. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A schematic diagram of the blasthole arrangement structure of the working face of a hard rock tunnel with a small or medium cross section provided by the present invention;

[0030] Figure 2 for Figure 1 Schematic diagram of the projection of the middle blasthole on the horizontal plane;

[0031] Figure 3 This is a schematic diagram of the filling in the blasthole;

[0032] In the figure: 1-working face, 2-first groove oblique eye, 3-second groove oblique eye, 4-first groove straight eye, 5-second groove straight eye, 6-expanded groove eye, 7-auxiliary eye, 8-peripheral eye, 9-bottom eye, 10-first center plane, 11-leakage prevention area, 12-explosive, 13-gun plug, 14-gun mud, 15-detonator, 16-detonator fuse. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] The purpose of the present invention is to provide a blasthole arrangement structure and blasting method for the working face of a hard rock tunnel with a small or medium section, so as to solve the problems existing in the above-mentioned prior art, and to effectively improve the trenching effect, trenching efficiency and tunnel excavation efficiency.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Embodiment 1

[0037] like Figures 1 to 3As shown, the present embodiment provides a blasthole arrangement structure of a working face of a hard rock tunnel with a small or medium section, comprising a working face 1 and blastholes, wherein the blastholes comprise a plurality of first slotted oblique eyes 2, a plurality of second slotted oblique eyes 3, a plurality of first slotted straight eyes 4, a plurality of second slotted straight eyes 5, a plurality of expanded slot eyes 6, a plurality of auxiliary eyes 7, a plurality of peripheral eyes 8 and a plurality of bottom eyes 9; the blastholes can be filled with explosives 12 and pluggers, and the pluggers can plug the blastholes; the working face 1 is bilaterally symmetrical about a first center plane 10; the first slotted oblique eyes 2 are arranged in sequence in the longitudinal direction, and the distances from the mouths of the first slotted oblique eyes 2 to the first center plane 10 are equal, and the first slotted oblique eyes 2 gradually approach the first center plane 10 from the working face 1 to the bottom of the first slotted oblique eyes 2; the number of the second slotted oblique eyes 3 is equal to the number of the first slotted oblique eyes 2 The amounts are equal, the second grooved oblique eye 3 corresponds to the first grooved oblique eye 2 one by one, and the second grooved oblique eye 3 and the first grooved oblique eye 2 are arranged symmetrically about the first center plane 10; a first grooved straight eye 4 is arranged between any two adjacent first grooved oblique eyes 2, and a second grooved straight eye 5 is arranged between any two adjacent second grooved oblique eyes 3, and each second grooved straight eye 5 is symmetrical with each first grooved straight eye 4 about the first center plane 10; each expanded groove eye 6 is arranged above the first grooved oblique eye 2 and the second grooved oblique eye 3; each auxiliary eye 7 is arranged on the outside of the first grooved oblique eye 2, the second grooved oblique eye 3 and the expanded groove eye 6; each bottom eye 9 is arranged below the first grooved oblique eye 2 and the second grooved oblique eye 3; each peripheral eye 8 is arranged on the outside of the auxiliary eye 7, and each peripheral eye 8 and each bottom eye 9 form a circle.

[0038] The blasthole arrangement structure of the working face of a small and medium-section hard rock tunnel provided in this embodiment is provided with a first slotted slant eye 2 and a second slotted slant eye 3 on the working face 1, and each first slotted slant eye 2 is arranged in sequence in the longitudinal direction, the distance between the eye opening of each first slotted slant eye 2 and the first center plane 10 is equal, each first slotted slant eye 2 gradually approaches the first center plane 10 from the working face 1 to the eye bottom of the first slotted slant eye 2, and the second slotted slant eye 3 is arranged symmetrically with the first slotted slant eye 2 about the first center plane 10, so that after the first slotted slant eye 2 and the second slotted slant eye 3 are filled with explosives 12 and detonated, the rocks in the area surrounded by each first slotted slant eye 2 and each second slotted slant eye 3 can be thrown out, and a terrace-shaped groove cavity can be obtained on the rock mass, and hereby On this basis, the first slotting straight eye 4 and the second slotting straight eye 5 are filled with explosives 12 and detonated, so that the rocks at the corners of the terraced slot cavity can be thrown out, especially the rocks at the bottom corners of the terraced slot cavity can be thrown out, so as to obtain a rectangular slot cavity, and an innovative slotting blasting structure of the first slotting oblique eye 2, the second slotting oblique eye 3, the first slotting straight eye 4 and the second slotting straight eye 5 of the small and medium-section hard rock tunnel is provided, which has a unique slotting blasting mechanism, that is, the first slotting oblique eye 2 and the second slotting oblique eye 3 are used to blast the terraced slot cavity first, and then the first slotting straight eye 4 and the second slotting straight eye 5 are used to slot, which can ensure that the first slotting oblique eye 2, the second slotting oblique eye 3, the first slotting straight eye 4 and the second slotting straight eye 5 The gathering of blasting energy at the bottom can ensure the range of hard rock crushing at the bottom of the first slotting oblique eye 2, the second slotting oblique eye 3, the first slotting straight eye 4 and the second slotting straight eye 5, blast out the bottom slot cavity, and improve the overall slotting effect. In addition, the blocking effect of the plugger prolongs the explosion action time of the fundus of the first slotting straight eye 4 and the second slotting straight eye 5, fully crushes the fundus rock, and ensures that the bottom slot cavity can collapse. Combined with the unique composite slotting structure, it can not only effectively avoid the "pulling the barrel" phenomenon ("pulling the barrel" is similar to firing a blank gun, that is, the explosives explode in the blasthole without any progress, or the footage is very small, like being pulled out directly), but also can effectively increase the slotting blasting depth, creating a good opportunity for the auxiliary eye 7 blasting. Good conditions, innovative slotting methods, improve slotting blasting effects, and thus increase blasting footage and light blasting quality, speed up excavation construction, shorten construction period, change Party A's negative views, and reduce costs; after slotting is completed, the expanded slot eye 6, auxiliary eye 7, peripheral eye 8 and bottom eye 9 are gradually filled with explosives 12 and detonated to achieve full-section blasting, wherein the expanded slot eye 6 is filled with explosives 12 and detonated, which can expand the above rectangular slot cavity upward toward the tunnel arch direction, the auxiliary eye 7 is filled with explosives 12 and detonated, which can further expand the above rectangular slot cavity from the inside to the outside on the basis of expanding upward toward the tunnel arch direction, the peripheral eye 8 and bottom eye 9 are filled with explosives 12 and detonated, which can control the forming contour of the tunnel section.

[0039] As a more preferred implementation of this embodiment, the number of the first groove oblique eyes 2 is four, the number of the second groove oblique eyes 3 is four, the number of the first groove straight eyes 4 and the number of the second groove straight eyes 5 are both three, the structure is simple, the groove cutting effect is better, and the groove cutting efficiency is higher.

[0040] As a more preferred implementation manner of this embodiment, a leak-proof zone 11 is left between the fundus of the second grooved slant eye 3 and the fundus of the first grooved slant eye 2, and the width of the leak-proof zone 11 is 200mm~600mm, which can effectively prevent the fundus of the second grooved slant eye 3 and the fundus of the first grooved slant eye 2 from being pierced and connected and leaking during blasting, and prevent the blasting in the second grooved slant eye 3 and the blasting in the first grooved slant eye 2 from interfering with each other, thereby realizing the accumulation of bottom blasting energy; among which it is more preferred that the width of the leak-proof zone 11 is 400mm.

[0041] As a more preferred implementation method of this embodiment, the diameter of the blasthole is 40 mm, so that the drilling construction can be carried out using a φ38 mm straight alloy steel drill bit (a diamond drill bit is used when encountering particularly dense granite with very good integrity), which significantly reduces the rock drilling resistance and speeds up the drilling speed.

[0042] As a more preferred implementation manner of this embodiment, the distance from the eye of the first groove oblique eye 2 to the first center plane 10 is 1000mm~1500mm, and the distance between any two adjacent first groove oblique eyes 2 is 800mm~1000mm, the groove excavation efficiency is high, and the groove excavation effect is better; among them, more preferably, the distance from the eye of the first groove oblique eye 2 to the first center plane 10 is 1200mm, and the distance between any two adjacent first groove oblique eyes 2 is 800mm.

[0043] As a more preferred implementation of this embodiment, each auxiliary eye 7 is divided into at least two auxiliary eye layers from the inside to the outside, the distance between any two adjacent auxiliary eyes 7 in the same layer is 900mm~1100mm, the distance between any two adjacent auxiliary eye layers is 1000mm~1500mm, the distance from the eye opening of the first grooved oblique eye 2 to the innermost auxiliary eye layer is 1000mm~1500mm, the peripheral eye 8 forms a peripheral eye layer, the distance from the peripheral eye layer to the outermost auxiliary eye layer is 600mm~900mm, and the distance between any two adjacent peripheral eyes 8 is 450mm~600mm, the blasting efficiency is high and the blasting effect is good, wherein the number of layers of the auxiliary eyes 7 can be increased according to the size of the cross-sectional area; wherein preferably, the distance between any two adjacent auxiliary eyes 7 in the same layer is 1000mm, the distance between any two adjacent auxiliary eye layers is 1000mm, the distance from the eye mouth of the first groove oblique eye 2 to the innermost auxiliary eye layer is 1000mm, the peripheral eye 8 forms a peripheral eye layer, the distance from the peripheral eye layer to the outermost auxiliary eye layer is 800mm, and the distance between any two adjacent peripheral eyes 8 is 500mm.

[0044] As a more preferred implementation manner of this embodiment, the projection distance between the eye mouth of the first groove oblique eye 2 and the eye bottom of the first groove oblique eye 2 on the first center plane 10 is equal to the depth of the first groove straight eye 4 and the depth of the bottom eye 9. The depth of the first groove straight eye 4 is greater than the depth of the auxiliary eye 7, the peripheral eye 8 and the expanded groove eye 6, so as to achieve full-section blasting.

[0045] As a more preferred implementation manner of this embodiment, the depth of the first groove straight eye 4 is 4000mm~4200mm, and the depths of the auxiliary eye 7, the peripheral eye 8 and the expanded groove eye 6 are all 3700mm~3800mm; among which it is more preferred that the depth of the first groove straight eye 4 is 4000mm, and the depths of the auxiliary eye 7, the peripheral eye 8 and the expanded groove eye 6 are all 3800mm, which can also be adjusted according to actual blasting requirements.

[0046] Furthermore, the plugger includes a gun plug 13 and gun mud 14, which are alternately arranged in the blasthole and combined to enhance the plugging ability; before detonation, the detonator 15 is inserted into the explosive 12 filled in the blasthole, one end of the detonator lead 16 is connected to the detonator 15, and the other end of the detonator lead 16 is passed through the gun plug 13 and the gun mud 14 to the outside of the blasthole.

[0047] A specific application example of the blasthole arrangement structure for the working face of a small and medium-section hard rock tunnel provided in this embodiment is as follows:

[0048] The total length of the tunnel section of a water diversion project is 46492.21m, of which the drilling and blasting construction section is 9111.12m long; the excavation section is a straight wall circular arch with a width of 8.0m and a height of 9.0m, and the cross-sectional area is 65.12m 2 , belonging to small and medium sections. The rock type is mainly granite with good integrity, rock compression strength of 78MPa~100.5MPa, and firmness coefficient f=7.8~10, belonging to Class III hard rock. The construction organization adopted by the tunnel is to blast and excavate first, then spray anchor, and finally use a trolley for reinforced concrete lining (there are small sections of intermittent expansion, and full-span bracket templates are used for cast-in-place).

[0049] The original plan was: excavation using a YT-28 air-leg rock drill, a 42mm diameter cross drill, and smooth blasting technology with non-electric millisecond detonators. The diamond straight hole cutting method was adopted, the cutting hole depth was 3.5m, the other blast holes were all 3.0m deep, the total number of blast holes was 93, the total amount of explosives was 198.5Kg, the penetration of each blast hole was 1.8m to 2.2m, the remaining blast holes were 0.8m to 1.2m long, and the unit consumption of explosives reached 1.4Kg / m 3 ~1.7Kg / m 3 , the blasthole utilization rate was 60.0% to 73.3%, the footage was too low, the cost was too high, and the construction progress and construction period were seriously behind the contract requirements signed with Party A. Specific shortcomings: Although the depth of the groove hole was 3.5m, the blasthole was not blocked after charging, and the remaining length of the groove hole after blasting was 1.3m to 1.7m, and the grooving effect was very poor; the footage of each blast was only 1.8m to 2.2m, and only 63m to 75m of tasks were completed per month, and the construction progress was slow; due to the low footage and long residual blastholes, the explosive consumption was as high as 1.4Kg / m 3 ~1.7Kg / m 3 During the blasting process, flying rocks travel a long distance, damaging air ducts, cables, lighting, etc.; the smooth blasting effect is poor, resulting in partial over-excavation, increased initial support for shotcrete, increased costs, and obvious losses; the use of large-diameter cross drill bits has a slow drilling speed, consumes a lot of high-pressure air, and increases mechanical wear, resulting in increased costs.

[0050] The new scheme for arranging the blastholes of the working face of a small and medium-sized hard rock tunnel provided by the present embodiment is as follows: a two-layer gantry work platform is used, 16 to 20 YT-30 air drills, φ18mm×4.5m hollow hexagonal steel drill rods, and φ38mm straight alloy steel drill bits (a diamond drill bit is used when encountering particularly dense granite with very good integrity), and personnel, drills, and quality are determined. Drilling, eye sweeping, charge charging, plugging of blast plugs 13, and blasting mud 14 are carried out in layers and zones, and the blasting footage and over-excavation and under-excavation conditions are evaluated. The first slotting oblique eye 2 and the second slotting oblique eye 3 are designed to have four each, i.e., eight slotting oblique eyes in total, the first slotting straight eye 4 and the second slotting straight eye 5 are designed to have three each, i.e., six slotting straight eyes in total, five slotting expansion eyes 6, and two layers of auxiliary eyes 7, i.e., thirty-five in total, forty-three peripheral eyes 8, nine bottom eyes 9, and one hundred and six full-section blastholes in total. After drilling is completed, use a sweeper to blow out the remaining debris and water in each blast hole using compressed air to ensure that the bottom of the hole is clean.

[0051] Blast hole charging structure:

[0052] Both the oblique and straight grooves are loaded with explosives in a continuous forward direction, and the explosives 12 are pushed into the bottom of the blasthole with a blast stick, and the remaining length of the blasthole is sealed with (1 blast plug 13 + 1 section of blast mud 14) + (1 blast plug 13 + 1 section of blast mud 14).

[0053] The auxiliary hole 7 is charged as designed, and the remaining hole length is sealed with 1 gun plug 13 + 1 section of gun mud 14.

[0054] After the bottom hole 9 is charged as designed, it is sealed with 1 gun plug 13 + 1 section of gun mud 14.

[0055] After the peripheral hole 8 is charged according to the design, the hole mouth is sealed with a gun plug 13 + a 0.3m long gun mud 14.

[0056] Except the slotted oblique eye, the slotted straight eye and the bottom eye 9, other blast holes only use one blast plug 13, the purpose is to shorten the plugging operation time.

[0057] Tunnel blasthole arrangement Figure 1 and Figure 2 As shown, the charge structure is as Figure 3 The blasting parameter design details are shown in Table 1, and the expected blasting effect is shown in Table 2.

[0058] The designed charge diameter is 35mm, the borehole diameter is 40mm, and the charge decoupling coefficient is 40 / 35=1.14.

[0059] The improved effect of the new scheme of the blasthole arrangement structure of the working face of the small and medium-section hard rock tunnel provided by the present embodiment is as follows: the large diameter (φ42mm) cross drill bit is changed to a small diameter (φ38mm) straight drill bit (the drill rod can only drill into the rock when rotating and impacting at the same time. If the drill rod is longer, the curvature during rotation is larger, and the drilling diameter is larger), which significantly reduces the rock drilling resistance and speeds up the drilling speed. The long drill rod is used to drill holes in one time, which improves the drilling efficiency and shortens the drilling time by 1.0 hour to 1.5 hours; the blasting footage is increased from the original 1.8m to 2.2m to 3.3m to 3.5m, the blasthole utilization rate is increased from the original 65% to 95%, and the construction progress is increased from the original 63m to 75m per month to 180m to 220m per month, and can reach up to 228m per month. Due to the improved construction progress, the construction plan issued by Party A can be completed in excess every month, and the construction organization enters a virtuous circle. In addition, the shortened drilling time reduced compressed air consumption, the increased penetration reduced the consumption of detonators and explosives, the faster the progress, the reduced equipment costs, electricity costs and other promotional costs, and the smooth surface blasting achieved good results, reducing over-excavation and under-excavation, reducing the amount of initial support shotcrete, and shortening the initial support time; saving construction costs and avoiding idle work.

[0060] Table 1 Tunnel hard rock blasting parameter design

[0061]

[0062] Table 2 Tunnel surrounding rock parameters and expected blasting effects

[0063]

[0064]

[0065] Embodiment 2

[0066] This embodiment provides a blasting method, which uses the blasthole arrangement structure of the working face of a small and medium-section hard rock tunnel in the first embodiment, and includes the following steps:

[0067] Step 1: punch a first slotting oblique eye 2, a second slotting oblique eye 3, a first slotting straight eye 4, a second slotting straight eye 5, an expanded slot eye 6, an auxiliary eye 7, a peripheral eye 8 and a bottom eye 9 on a working surface 1;

[0068] Step 2: Fill the first slotted oblique eye 2, the second slotted oblique eye 3, the first slotted straight eye 4, the second slotted straight eye 5, the expanded slot eye 6, the auxiliary eye 7, the peripheral eye 8 and the bottom eye 9 with explosives 12, and then install the plugging device;

[0069] Step 3: detonating the explosives 12 in the first cutout oblique eye 2 and the second cutout oblique eye 3;

[0070] Step 4: detonating the explosives 12 in the first cut straight hole 4 and the second cut straight hole 5;

[0071] Step 5: detonating the explosive 12 in the expanded slot 6;

[0072] Step 6: Detonation of the explosive 12 in the auxiliary hole 7;

[0073] Step 7: Detonation of explosives 12 in peripheral holes 8;

[0074] Step 8: The explosive 12 in the bottom hole 9 is detonated.

[0075] The blasting method provided in this embodiment is to set the first slotted eye 2 and the second slotted eye 3 on the working face 1, and to arrange the first slotted eyes 2 in sequence in the longitudinal direction, the distances from the mouths of the first slotted eyes 2 to the first center plane 10 are equal, and the first slotted eyes 2 gradually approach the first center plane 10 from the working face 1 to the bottom of the eye of the first slotted eye 2, and the second slotted eye 3 and the first slotted eye 2 are arranged symmetrically about the first center plane 10, so that after the first slotted eye 2 and the second slotted eye 3 are filled with explosives 12 and detonated, the rocks in the areas surrounded by the first slotted eyes 2 and the second slotted eyes 3 can be thrown out, and a terrace-shaped groove cavity can be obtained on the rock mass. On this basis, the first slotting straight eye 4 and the second slotting straight eye 5 are filled with explosives 12 and detonated, so that the rocks at the corners of the terraced slot cavity can be thrown out, especially the rocks at the bottom corners of the terraced slot cavity can be thrown out, so as to obtain a rectangular slot cavity, and an innovative slotting blasting structure of the first slotting oblique eye 2, the second slotting oblique eye 3, the first slotting straight eye 4 and the second slotting straight eye 5 in small and medium-section hard rock tunnels is provided, which has a unique slotting blasting mechanism, that is, the first slotting oblique eye 2 and the second slotting oblique eye 3 are used to blast the terraced slot cavity first, and then the first slotting straight eye 4 and the second slotting straight eye 5 are used to slot, which can ensure that the first slotting oblique eye 2 and the second slotting oblique eye The blasting energy at the bottom of eye 3, the first slot straight eye 4 and the second slot straight eye 5 is gathered, thereby ensuring the range of hard rock crushing at the bottom of the first slot oblique eye 2, the second slot oblique eye 3, the first slot straight eye 4 and the second slot straight eye 5, blasting the bottom slot cavity and improving the overall slotting effect. In addition, the plugging effect of the plugger prolongs the explosion time of the fundus of the first slot straight eye 4 and the second slot straight eye 5, fully crushes the fundus rock and ensures that the bottom slot cavity can collapse. Combined with the unique composite slotting structure, it can not only effectively avoid the "pulling tube" phenomenon, but also effectively increase the slotting blasting depth, creating good conditions for the blasting of the auxiliary eye 7, innovating the slotting method and improving the slotting effect. The blasting effect can be improved, thereby improving the blasting footage and the quality of light blasting, speeding up the excavation construction speed, shortening the construction period, changing the negative view of Party A and reducing the cost; after the trenching is completed, the expanded slot eye 6, the auxiliary hole 7, the peripheral hole 8 and the bottom hole 9 are gradually filled with explosives 12 and detonated, so as to realize the full-section blasting, wherein, the expanded slot eye 6 is filled with explosives 12 and detonated, so that the above rectangular slot cavity can be expanded upward toward the tunnel arch direction, the auxiliary hole 7 is filled with explosives 12 and detonated, so that the above rectangular slot cavity can be further expanded from the inside to the outside on the basis of expanding upward toward the tunnel arch direction, and the peripheral hole 8 and the bottom hole 9 are filled with explosives 12 and detonated, so as to control the forming contour of the tunnel section.

[0076] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A blasthole arrangement structure for a working face of a hard rock tunnel with a small or medium cross section, characterized in that: The blasthole comprises a working face and blastholes, wherein the blastholes include a plurality of first slotting oblique holes, a plurality of second slotting oblique holes, a plurality of first slotting straight holes, a plurality of second slotting straight holes, a plurality of expanded slot holes, a plurality of auxiliary holes, a plurality of peripheral holes and a plurality of bottom holes; The blasthole can be filled with explosives and a plugging device, and the plugging device can plug the blasthole; The working surface is bilaterally symmetrical about the first center plane; The first cut groove oblique eyes are arranged in sequence in the longitudinal direction, the distances from the eye openings of the first cut groove oblique eyes to the first central plane are equal, and the first cut groove oblique eyes gradually approach the first central plane from the working surface to the eye bottom of the first cut groove oblique eyes; The number of the second cut groove oblique eyes is equal to the number of the first cut groove oblique eyes, the second cut groove oblique eyes correspond to the first cut groove oblique eyes one by one, and the second cut groove oblique eyes and the first cut groove oblique eyes are arranged symmetrically with respect to the first center plane; A first straight hole is arranged between any two adjacent first slanted holes, and a second straight hole is arranged between any two adjacent second slanted holes, and each of the second straight holes is symmetrical with each of the first straight holes about the first center plane; Each of the expanded slot eyes is arranged above the first slotted oblique eye and the second slotted oblique eye; Each of the auxiliary eyes is arranged on the outer side of the first groove cutting oblique eye, the second groove cutting oblique eye and the expanded groove eye; Each of the bottom eyes is arranged below the first cutout oblique eye and the second cutout oblique eye; The peripheral eyes are arranged on the outside of the auxiliary eyes, and the peripheral eyes and the bottom eyes form a circle.

2. The blasthole arrangement structure for the working face of a hard rock tunnel with a small or medium cross section according to claim 1 is characterized in that: The number of the first cutout oblique eyes is four.

3. The blasthole arrangement structure for the working face of a small and medium-section hard rock tunnel according to claim 1 is characterized in that: A leak-proof area is left between the fundus of the second cutout oblique eye and the fundus of the first cutout oblique eye, and the width of the leak-proof area is 200 mm to 600 mm.

4. The blasthole arrangement structure for the working face of a small and medium-section hard rock tunnel according to claim 1 is characterized in that: The diameter of the blastholes is 40 mm.

5. The blasthole arrangement structure for the working face of a small and medium-section hard rock tunnel according to claim 1 is characterized in that: The distance from the opening of the first cutout oblique eye to the first center plane is 1000 mm to 1500 mm, and the distance between any two adjacent first cutout oblique eyes is 800 mm to 1000 mm.

6. The blasthole arrangement structure for the working face of a hard rock tunnel with a small or medium cross section according to claim 5 is characterized in that: Each of the auxiliary eyes is divided into at least two auxiliary eye layers from the inside to the outside, the distance between any two adjacent auxiliary eyes in the same layer is 900mm~1100mm, the distance between any two adjacent auxiliary eye layers is 1000mm~1500mm, the distance from the eye mouth of the first groove oblique eye to the innermost auxiliary eye layer is 1000mm~1500mm, the peripheral eye forms a peripheral eye layer, the distance from the peripheral eye layer to the outermost auxiliary eye layer is 600mm~900mm, and the distance between any two adjacent peripheral eyes is 450mm~600mm.

7. The blasthole arrangement structure for the working face of a hard rock tunnel with a small or medium cross section according to claim 1 is characterized in that: The projection distance between the eye opening of the first groove oblique eye and the eye bottom of the first groove oblique eye on the first center plane is equal to the depth of the first groove straight eye and the depth of the bottom eye, and the depth of the first groove straight eye is greater than the depths of the auxiliary eye, the peripheral eye and the expanded groove eye.

8. The blasthole arrangement structure for the working face of a hard rock tunnel with a small or medium cross section according to claim 7 is characterized in that: The depth of the first straight groove eye is 4000mm-4200mm, and the depths of the auxiliary eye, the peripheral eye and the expanded groove eye are all 3700mm-3800mm.

9. The blasthole arrangement structure for the working face of a hard rock tunnel with a small or medium cross section according to claim 1 is characterized in that: The plugging device comprises a gun plug and gun mud, and the gun plug and the gun mud are alternately arranged in the gun hole.

10. A blasting method, using the blasthole arrangement structure for the working face of a small and medium-section hard rock tunnel as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: punch the first slotting oblique eye, the second slotting oblique eye, the first slotting straight eye, the second slotting straight eye, the expanded slot eye, the auxiliary eye, the peripheral eye and the bottom eye on the working surface; Step 2: Filling explosives into the first slotted oblique eye, the second slotted oblique eye, the first slotted straight eye, the second slotted straight eye, the expanded slot eye, the auxiliary eye, the peripheral eye and the bottom eye, and then installing the plugging device; Step 3: detonating the explosives in the first cutout oblique eye and the second cutout oblique eye; Step 4: detonating the explosives in the first cutout straight eye and the second cutout straight eye; Step 5: Detonating the explosives in the expanded slot; Step 6: Detonate the explosives in the auxiliary eyes; Step 7: Detonate the explosives in the surrounding eyes; Step 8: Detonate the explosives in the bottom eye.

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