Small-section tunnel long and short straight hole combined underholing blasting charging structure

Abstract

The utility model discloses a small-section tunnel long and short straight hole combined underholing blasting charging structure, which is characterized in that deep underholing holes and shallow underholing holes are matched with each other, and a non-charged part at the upper part of a deep hole provides a free surface and a crushing and expanding space for the shallow hole during shallow hole blasting; the length of the shallow hole is close to the optimal burial depth, and the rock is in a broken impact state during blasting: the rock near the free surface is damaged, and the volume of a blasting funnel formed in the rock is maximum. A funnel formed by shallow hole blasting provides a new free surface and a compensation space for deep hole blasting, and meanwhile, the generated new free surface can reduce the anti-explosion capacity and the minimum resistance line of the rock. Therefore, the problem that the residual hole is too long and the rock at the bottom of the deep hole cannot be thrown out after the deep hole straight cut blasting is avoided, and the blasting footage is increased from 1.8-2.0 m to more than 2.5 m.

Description

Technical Field

[0001] The utility model belongs to tunnel blasting technology and relates to a small-section tunnel long and short straight hole combined slot blasting charging structure. Background Art

[0002] The international cooperation defines the cross-sectional area as 3.0~10.0m 2 Tunnels are classified as small-section tunnels. When drilling and blasting is used for small-section tunnels, straight-eye slots are usually used to obtain longer blasting footage. The length of the straight-eye slots is the same, and the hole depth is basically 2.5m. Due to the large effect of blasting clamping, the blasting footage is 2m, usually leaving a long residual hole, which seriously affects the blasting footage and has low excavation efficiency, and cannot meet the needs of infrastructure construction in today's society. Therefore, improving the blasting footage of small-section tunnels plays an important role in alleviating social needs, reducing workers' operating cycles and production risks.

[0003] In recent years, with the rapid development of my country's national economy, the problem of rapid tunnel construction needs to be solved urgently. Among them, the slot blasting of small end face tunnels plays a key step in the entire blasting process, forming a slot cavity, creating a free surface for subsequent blasting, and providing compensation space for rock crushing. The quality of rock breaking and cavity formation will directly affect the blasting effect of subsequent blasting holes. When the slot hole is detonated, there is only one free surface, and the clamping force of the surrounding rocks is very large. Compared with the other blasting holes, the clamping effect is the most obvious, and this effect increases with the increase of tunnel burial depth. In addition, due to the small cross-sectional span, the inclination angle and depth of the slot eye are limited, which in turn limits the blasting footage. Therefore, it is of great significance to study reasonable slotting methods and slotting parameters to completely crush and throw out the rock, so as to obtain a higher blasting hole utilization rate, which is of great significance for guiding the safe and rapid blasting construction of small section tunnels. Utility Model Content

[0004] In view of this, the utility model provides a long and short straight-eye combined slotting electronic detonator blasting technology for small-section tunnels. In order to improve the cycle footage and the utilization rate of blastholes, it is necessary to increase the depth of blastholes. The inclined-eye slotting used in small-section tunnels is greatly restricted by the section. The slotting eye angle is generally 55° to 75° with the working surface, which makes it difficult to carry out deep hole blasting. Therefore, straight-eye slotting is selected, and the slotting holes are parallel and perpendicular to the working surface. As the depth of the blasthole increases, the clamping force of the rock increases, and the anti-explosion ability is enhanced. When the explosive is far away from the working surface, no blasting funnel will be generated. Columnar charges are used in tunnel excavation. Since the columnar charges are long, the distance from the bottom explosive to the free surface is much greater than the minimum resistance line. Therefore, it is difficult to fully utilize the blasthole, and the blasthole utilization rate is further reduced as the hole depth increases.

[0005] The specific technical solution of the utility model is as follows:

[0006] A small-section tunnel long and short straight hole combined slot blasting charging structure, comprising:

[0007] The slotting holes adopt straight-eye slotting, including 5 groups of slotting holes, each group of slotting holes includes a shallow slotting hole and a deep slotting hole, the hole depth of the shallow slotting hole is 150cm, the hole depth of the deep slotting hole is 300cm, the shallow slotting hole is located 10cm away from the deep slotting hole, and 100ms after the shallow slotting hole is blasted, the deep slotting hole is detonated again; among them, 4 groups of slotting holes are symmetrically distributed on both sides of the center line of the tunnel in a rectangular shape, the vertical hole spacing of the shallow slotting holes is 40cm, the deep slotting holes are located on the vertical outer side of the shallow slotting holes, and the vertical hole spacing of the deep slotting holes is 60cm; there is also a group of slotting holes located on the center line of the tunnel, set at the center of the square;

[0008] When the shallow cut hole is blasted, the uncharged portion of the upper part of the deep cut hole provides a free surface and a crushing expansion space for the shallow cut hole; when the deep cut hole is blasted, the funnel formed by the shallow cut hole blasting provides a free surface for the deep hole;

[0009] An expansion hole is provided outside the slot hole, a side collapse hole is provided outside the expansion hole, and two rows of collapse holes are provided on the upper part of the slot hole, namely, a first upper collapse hole and a second upper collapse hole, wherein the second upper collapse hole is located above the first upper collapse hole;

[0010] A bottom plate hole and peripheral holes are arranged along the contour edge of the cross-sectional area, and the bottom plate hole is located below the cutout hole;

[0011] The blasthole depths of the expansion hole, side cave-in hole, first upper cave-in hole, second upper cave-in hole, bottom plate hole and peripheral hole are all 2.7-2.8m;

[0012] The explosives are charged in the blast holes drilled on the drilling and blasting section, and the explosives are all charged with electronic detonators;

[0013] A delay is set for the electronic detonator in each blasthole; wherein the shallow groove holes are uniformly set to 0 milliseconds, the deep groove holes are uniformly set to 100 milliseconds, the expanded slot holes are uniformly set to 200 milliseconds, the side collapse holes are uniformly set to 300 milliseconds, the first upper collapse holes are uniformly set to 400 milliseconds, the second upper collapse holes are uniformly set to 500 milliseconds, the bottom plate holes are uniformly set to 600 milliseconds, and the peripheral holes are uniformly set to 700 milliseconds.

[0014] Furthermore, the number of the expansion slot holes is 8, the number of the side collapse holes is 6, the number of the first upper collapse holes is 3, the number of the second upper collapse holes is 2, the number of the bottom plate holes is 5, and the number of the peripheral holes is 15.

[0015] Furthermore, the expansion holes are arranged vertically, with a vertical hole spacing of 40 cm, and a spacing between the expansion holes and the cut holes is 50 cm.

[0016] Furthermore, the side collapse holes are arranged vertically, three on each side, and the distance between the side collapse holes and the expansion slot hole row is 50 cm.

[0017] Furthermore, the aperture of all blastholes is 42 mm and the charge diameter is 32 mm.

[0018] Furthermore, the amount of medicine for a single hole of the shallow groove is 4 sticks, and the amount of medicine for a single hole of the deep groove is 6 sticks, and the amount of medicine for each stick is 0.3kg.

[0019] Furthermore, the single-hole charge of the expansion slot hole is 8 sticks, the single-hole charge of the side collapse hole is 7 sticks, the single-hole charge of the first upper collapse hole is 6 sticks, the single-hole charge of the second upper collapse hole is 6 sticks, the single-hole charge of the bottom plate hole is 8 sticks, the single-hole charge of the peripheral holes is 3-4 sticks, and the charge of each stick is 0.3kg.

[0020] Furthermore, the delay error of the electronic detonator is 0.1-0.5 milliseconds.

[0021] The utility model has the following technical effects:

[0022] During shallow hole blasting, the uncharged upper portion of the deep hole provides a free surface and crushing expansion space for the shallow hole; the length of the shallow hole is close to the optimal burial depth, and the rock is in a crushing impact state during blasting: the rock near the free surface will be destroyed, and the blasting funnel formed in the rock will have the largest volume. The funnel formed by shallow hole blasting provides a new free surface and compensation space for deep hole blasting, and the newly generated free surface can reduce the rock's explosion resistance and minimum resistance line. This avoids the problem of the residual hole being too long and the rock at the bottom of the deep hole being unable to be thrown out after deep hole straight eye slot blasting. Figure 4 As shown: OA represents the anti-explosion ability of rock, O1A1 represents the anti-explosion ability of rock after shallow hole blasting. BC represents the rock breaking ability of explosives. The left figure is a schematic diagram of the rock breaking ability of deep hole blasting alone, and the right figure is a schematic diagram of the rock breaking ability of deep and shallow holes in cooperation with each other. In the left figure, when BC is located above OA in deep hole blasting alone, it means that the rock can be effectively broken and thrown. When OA is located above BC, it means that the rock is in an elastic deformation state: when the explosive is far away from the free surface, the energy generated by the explosion can only cause the rock to deform elastically. When the explosive load is unloaded, the rock will release the stored elastic potential energy and return to its original state without damage. In the right figure, when BC is located above OA in shallow hole blasting, it means that the rock can be effectively broken and thrown, forming a new free surface and a new anti-explosion curve O1A1. When BC is located above the new anti-explosion curve O1A1 in deep hole blasting, it can still effectively break the rock and throw it to form a larger slot cavity.

[0023] Based on the above theory, 5 one-stage shallow holes are detonated simultaneously at 0ms, and the time required for the cracks in the rock after blasting is 1-2ms, and the time required to separate from the parent rock is generally 8-68ms. In order to ensure that the rock blasted from the front blasthole is completely ejected and create a good air surface for subsequent blastholes, the patent has a delay interval of 100ms. Since the center of the charge in the shallow hole reaches the optimal burial depth from the free surface, the broken rock has been completely ejected at 100ms to form the largest blasting funnel, providing a free surface and compensation space for deep hole blasting. At this time, the center of the 5 two-stage deep hole charge packs has just reached the optimal burial depth from the new free surface. At 200ms, the broken rock in the deep hole has been completely ejected to form a slot cavity with a depth of 2.8m. At this time, 8 three-stage expansion slot holes are detonated simultaneously. Explosion; at 300ms, the rock inside the expansion hole is thrown out, and at this time, the 6 four-section side collapse holes are detonated at the same time; at 400ms, the 6 four-section side collapse holes throw out all the rocks under the face, and at this time, the 3 five-section upper collapse holes 1 are detonated at the same time; at 500ms, the upper 3 collapse holes 1 throw out all the rocks, and the 3 collapse holes 2 are detonated at the same time; at 600ms, the upper 3 collapse holes 2 throw out all the rocks, and the 5 bottom plate holes are detonated at the same time; at 700ms, 15 peripheral holes are detonated at the same time, forming a relatively smooth contour surface, and the blasting footage can reach more than 2.5m.

[0024] It can be seen from the above technical solution of the utility model that the utility model has the following technical effects through the long and short straight-eye combined slotted electronic detonator blasting technology: the blasting footage is increased from 1.8--2.0m to more than 2.5m. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram showing four different states according to the rock-breaking effect of columnar charges.

[0026] Figure 2 This is a schematic diagram of the Livingston blasting funnel curve.

[0027] Figure 3 It is a blasthole arrangement diagram of the utility model.

[0028] Figure 4 It is a schematic diagram of the deep and shallow hole coordinated blasting principle of the utility model. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these embodiments are all within the scope of protection of the present invention.

[0030] According to the rock breaking effect of columnar charge, it can be divided into four different states: Figure 1As shown: ① Elastic deformation state: When the explosive is far away from the free surface or the explosive energy is small, the energy generated by the explosion can only cause the rock to deform elastically. When the explosive load is unloaded, the rock will release the stored elastic potential energy to return to its original state without damage. The minimum burial depth to maintain this state is WC. ② Crushing impact state: When the buried depth of the explosive is less than WC, the rock near the free surface will be destroyed, and a blasting funnel will begin to form in the rock. As the buried depth decreases, the volume of the blasting funnel increases. There is an optimal buried depth value WZ that maximizes the volume of the formed blasting funnel. ③ Crushing state: The buried depth of the explosive is further reduced on the basis of WZ, the volume of the blasting funnel decreases, the degree and amount of rock crushing near the free surface increases, and the distance thrown increases. ④ Air explosion state: The buried depth of the explosive is close to the free surface. At this time, only a small part of the energy generated by the explosion acts on the rock, and most of it is distributed in the air. The critical buried depth of the air explosion state is 0.

[0031] According to Livingston's theory, the energy and speed of explosives transferred to rock when they are blasted in rock mass depends on factors such as rock properties, explosive performance, charge size and charge burial depth. The theory gives the relationship between burial depth, explosive amount and rock properties:

[0032]

[0033]

[0034] Where: ER is the rock deformation energy coefficient, Q is the amount of explosives, WC is the critical burial depth of the explosive package, Wz is the optimal burial depth of the explosive package, Δ I The best depth ratio.

[0035] The explosive packs used in tunnel blasting construction are relatively long. For the rock mass below the resistance line, a small part of the rock will be broken, but it will not be thrown out of the free surface due to limited energy; the rock mass close to the bottom of the blast hole will be in an elastic state, resulting in under-excavation. As the hole depth increases, the range of the elastic state and the elastic + crushing mixed state increases. According to the Livingston blasting funnel curve, Figure 2 As shown in the figure, relative burial depth refers to the ratio of actual burial depth to critical minimum resistance line. It can be seen that the funnel volume increases first and then decreases with the increase of relative burial depth. The left side of the optimal burial depth represents that the explosive energy is more distributed in rock crushing and air, and the funnel volume is smaller. The right side of the optimal burial depth represents that the explosion energy is more to deform the rock, and the part used for crushing is less. Therefore, the blast hole should not be too long in tunnel blasting.

[0036] Since the blast hole should not be too long in blasting, the utility model provides a long and short straight hole combined slot electronic detonator blasting technology. The blast hole arrangement is as follows Figure 3As shown, the slots are deep and shallow, with the shallow hole length of 1.5m or 1.8m and the deep hole length of 3m. To prevent explosions between adjacent blast holes, the deep and shallow holes are 10cm apart.

[0037] The specific technical solutions are as follows:

[0038] A small-section tunnel long and short straight hole combined slot blasting charging structure, comprising:

[0039] The slotting holes adopt straight-eye slotting, including 5 groups of slotting holes, each group of slotting holes includes a shallow slotting hole and a deep slotting hole, the hole depth of the shallow slotting hole is 150cm, the hole depth of the deep slotting hole is 300cm, the shallow slotting hole is located 10cm away from the deep slotting hole, and 100ms after the shallow slotting hole is blasted, the deep slotting hole is detonated again; among them, 4 groups of slotting holes are symmetrically distributed on both sides of the center line of the tunnel in a rectangular shape, the vertical hole spacing of the shallow slotting holes is 40cm, the deep slotting holes are located on the vertical outer side of the shallow slotting holes, and the vertical hole spacing of the deep slotting holes is 60cm; there is also a group of slotting holes located on the center line of the tunnel, set at the center of the square;

[0040] When the shallow cut hole is blasted, the uncharged portion of the upper part of the deep cut hole provides a free surface and a crushing expansion space for the shallow cut hole; when the deep cut hole is blasted, the funnel formed by the shallow cut hole blasting provides a free surface for the deep hole;

[0041] An expansion hole is provided outside the slot hole, a side collapse hole is provided outside the expansion hole, and two rows of collapse holes are provided on the upper part of the slot hole, namely, a first upper collapse hole and a second upper collapse hole, wherein the second upper collapse hole is located above the first upper collapse hole;

[0042] A bottom plate hole and peripheral holes are arranged along the contour edge of the cross-sectional area, and the bottom plate hole is located below the cutout hole;

[0043] The blasthole depths of the expansion hole, side cave-in hole, first upper cave-in hole, second upper cave-in hole, bottom plate hole and peripheral hole are all 2.7-2.8m;

[0044] The explosives are charged in the blast holes drilled on the drilling and blasting section, and the explosives are all charged with electronic detonators;

[0045] A delay is set for the electronic detonator in each blasthole; wherein the shallow groove holes are uniformly set to 0 milliseconds, the deep groove holes are uniformly set to 100 milliseconds, the expanded slot holes are uniformly set to 200 milliseconds, the side collapse holes are uniformly set to 300 milliseconds, the first upper collapse holes are uniformly set to 400 milliseconds, the second upper collapse holes are uniformly set to 500 milliseconds, the bottom plate holes are uniformly set to 600 milliseconds, and the peripheral holes are uniformly set to 700 milliseconds.

[0046] Furthermore, there are 8 expansion slot holes 3, 6 side collapse holes 4, 3 first upper collapse holes 5, 2 second upper collapse holes 6, 5 bottom plate holes 7, and 15 peripheral holes 8.

[0047] Furthermore, the expanded slot holes 3 are arranged vertically, with a vertical hole spacing of 40 cm, and a spacing between the expanded slot holes 3 and the cut slot holes is 50 cm.

[0048] Furthermore, the side collapse holes 4 are arranged vertically, three on each side, and the spacing between the side collapse holes 4 and the expansion slot holes 3 is 50 cm.

[0049] Furthermore, the aperture of all blastholes is 42 mm and the charge diameter is 32 mm.

[0050] Furthermore, the amount of medicine for each hole of the shallow groove hole 1 is 4, and the amount of medicine for each hole of the deep groove hole 2 is 6, and the amount of medicine for each hole is 0.3kg.

[0051] Furthermore, the single-hole amount of medicine of the expansion slot hole 3 is 8, the single-hole amount of medicine of the side collapse hole 4 is 7, the single-hole amount of medicine of the first upper collapse hole 5 is 6, the single-hole amount of medicine of the second upper collapse hole 6 is 6, the single-hole amount of medicine of the bottom plate hole 7 is 8, the single-hole amount of medicine of the peripheral hole 8 is 3-4, and the amount of medicine per hole is 0.3kg.

[0052] Furthermore, the delay error of the electronic detonator is 0.1-0.5 milliseconds.

[0053] Furthermore, at 0ms, the five first-stage shallow holes 1 are detonated simultaneously. At 100ms, the broken rocks have been completely thrown out, forming the largest blasting funnel, providing a free surface and compensation space for deep hole blasting. At this time, the center of the five second-stage deep holes 2 is just at the optimal burial depth from the new free surface, and the five second-stage deep holes 2 are detonated simultaneously. At 200ms, the broken rocks in the deep holes 2 have been completely thrown out to form a 2.8m deep slot cavity. At this time, the eight three-stage slot expansion holes 3 are detonated simultaneously. At 300ms, the rock inside the slot expansion hole 3 is The rocks are thrown out, and at this time, the six four-section side collapse holes 4 are detonated at the same time; at 400ms, the six four-section side collapse holes 4 throw out all the rocks under the face, and at this time, the three five-section upper collapse holes 1 are detonated at the same time; at 500ms, the three upper first collapse holes throw out all the rocks, and the three second collapse holes are detonated at the same time; at 600ms, the three upper second collapse holes throw out all the rocks, and the five bottom plate holes 7 are detonated at the same time; at 700ms, the 15 peripheral holes 8 are detonated at the same time, forming a relatively smooth contour surface, and the blasting footage can reach more than 2.5m.

[0054] During shallow hole blasting, the uncharged upper portion of the deep hole provides a free surface and crushing expansion space for the shallow hole; the length of the shallow hole is close to the optimal burial depth, and the rock is in a crushing impact state during blasting: the rock near the free surface will be destroyed, and the blasting funnel formed in the rock will have the largest volume. The funnel formed by shallow hole blasting provides a new free surface and compensation space for deep hole blasting, and the newly generated free surface can reduce the rock's explosion resistance and minimum resistance line. This avoids the problem of the residual hole being too long and the rock at the bottom of the deep hole being unable to be thrown out after deep hole straight eye slot blasting. Figure 4 As shown: OA represents the anti-explosion ability of rock, O1A1 represents the anti-explosion ability of rock after shallow hole blasting. BC represents the rock breaking ability of explosives. The left figure is a schematic diagram of the rock breaking ability of deep hole blasting alone, and the right figure is a schematic diagram of the rock breaking ability of deep and shallow holes in cooperation with each other. In the left figure, when BC is located above OA in deep hole blasting alone, it means that the rock can be effectively broken and thrown. When OA is located above BC, it means that the rock is in an elastic deformation state: when the explosive is far away from the free surface, the energy generated by the explosion can only cause the rock to deform elastically. When the explosive load is unloaded, the rock will release the stored elastic potential energy and return to its original state without damage. In the right figure, when BC is located above OA in shallow hole blasting, it means that the rock can be effectively broken and thrown, forming a new free surface and a new anti-explosion curve O1A1. When BC is located above the new anti-explosion curve O1A1 in deep hole blasting, it can still effectively break the rock and throw it to form a larger slot cavity.

[0055] Based on the above theory, 5 one-stage shallow holes are detonated simultaneously at 0ms, and the time required for the cracks in the rock after blasting is 1-2ms, and the time required to separate from the parent rock is generally 8-68ms. In order to ensure that the rock blasted from the front blasthole is completely ejected and create a good air surface for subsequent blastholes, the patent has a delay interval of 100ms. Since the center of the charge in the shallow hole reaches the optimal burial depth from the free surface, the broken rock has been completely ejected at 100ms to form the largest blasting funnel, providing a free surface and compensation space for deep hole blasting. At this time, the center of the 5 two-stage deep hole charge packs has just reached the optimal burial depth from the new free surface. At 200ms, the broken rock in the deep hole has been completely ejected to form a slot cavity with a depth of 2.8m. At this time, 8 three-stage expansion slot holes are detonated simultaneously. Explosion; at 300ms, the rock inside the expansion hole is thrown out, and at this time, the 6 four-section side collapse holes are detonated at the same time; at 400ms, the 6 four-section side collapse holes throw out all the rocks under the face, and at this time, the 3 five-section upper collapse holes 1 are detonated at the same time; at 500ms, the upper 3 collapse holes 1 throw out all the rocks, and the 3 collapse holes 2 are detonated at the same time; at 600ms, the upper 3 collapse holes 2 throw out all the rocks, and the 5 bottom plate holes are detonated at the same time; at 700ms, 15 peripheral holes are detonated at the same time, forming a relatively smooth contour surface, and the blasting footage can reach more than 2.5m.

[0056] The above is only one of the embodiments of this patent, and does not limit this patent in other forms. Any technician familiar with this profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of this patent without departing from the content of the technical solution of this patent still falls within the protection scope of the technical solution of this patent.

Claims

1. A small-section tunnel long and short straight hole combined slot blasting charging structure, characterized in that: include: The slotting holes adopt straight-eye slotting, including 5 groups of slotting holes, each group of slotting holes includes a shallow slotting hole and a deep slotting hole, the hole depth of the shallow slotting hole is 150cm, the hole depth of the deep slotting hole is 300cm, the shallow slotting hole is located 10cm away from the deep slotting hole, and 100ms after the shallow slotting hole is blasted, the deep slotting hole is detonated again; among them, 4 groups of slotting holes are symmetrically distributed on both sides of the center line of the tunnel in a rectangular shape, the vertical hole spacing of the shallow slotting holes is 40cm, the deep slotting holes are located on the vertical outer side of the shallow slotting holes, and the vertical hole spacing of the deep slotting holes is 60cm; there is also a group of slotting holes located on the center line of the tunnel, set at the center of the square; When the shallow cut hole is blasted, the uncharged portion of the upper part of the deep cut hole provides a free surface and a crushing expansion space for the shallow cut hole; when the deep cut hole is blasted, the funnel formed by the shallow cut hole blasting provides a free surface for the deep hole; An expansion hole is provided outside the slot hole, a side collapse hole is provided outside the expansion hole, and two rows of collapse holes are provided on the upper part of the slot hole, namely, a first upper collapse hole and a second upper collapse hole, wherein the second upper collapse hole is located above the first upper collapse hole; A bottom plate hole and peripheral holes are arranged along the contour edge of the cross-sectional area, and the bottom plate hole is located below the cutout hole; The blasthole depths of the expansion hole, side cave-in hole, first upper cave-in hole, second upper cave-in hole, bottom plate hole and peripheral hole are all 2.7-2.8m; The explosives are charged in the blast holes drilled on the drilling and blasting section, and the explosives are all charged with electronic detonators; A delay is set for the electronic detonator in each blasthole; wherein the shallow groove holes are uniformly set to 0 milliseconds, the deep groove holes are uniformly set to 100 milliseconds, the expanded slot holes are uniformly set to 200 milliseconds, the side collapse holes are uniformly set to 300 milliseconds, the first upper collapse holes are uniformly set to 400 milliseconds, the second upper collapse holes are uniformly set to 500 milliseconds, the bottom plate holes are uniformly set to 600 milliseconds, and the peripheral holes are uniformly set to 700 milliseconds.

2. A small-section tunnel long and short straight hole combined slot blasting charging structure according to claim 1, characterized in that: There are 8 expansion slot holes, 6 side collapse holes, 3 first upper collapse holes, 2 second upper collapse holes, 5 bottom plate holes, and 15 peripheral holes.

3. A small-section tunnel long and short straight hole combined slot blasting charging structure according to claim 2, characterized in that: The expansion holes are arranged vertically, with a vertical hole spacing of 40 cm, and the spacing between the expansion holes and the cutting holes is 50 cm.

4. A small-section tunnel long and short straight hole combined slot blasting charging structure according to claim 3, characterized in that: The side collapse holes are arranged vertically, three on each side, and the distance between the side collapse holes and the expansion slot holes is 50 cm.

5. The long and short straight hole combined slot blasting charging structure for small-section tunnels according to claim 1 is characterized in that: The aperture of all blast holes is 42mm and the charge diameter is 32mm.

6. The small-section tunnel long and short straight hole combined slot blasting charging structure according to claim 1 is characterized in that: The amount of medicine for each hole of the shallow groove is 4 sticks, and the amount of medicine for each hole of the deep groove is 6 sticks, and the amount of medicine for each stick is 0.3kg.

7. A small-section tunnel long and short straight hole combined slot blasting charging structure according to claim 6, characterized in that: The single hole amount of the expansion slot hole is 8 sticks, the single hole amount of the side collapse hole is 7 sticks, the single hole amount of the first upper collapse hole is 6 sticks, the single hole amount of the second upper collapse hole is 6 sticks, the single hole amount of the bottom plate hole is 8 sticks, the single hole amount of the peripheral holes is 3-4 sticks, and the amount of each stick is 0.3kg.

8. The long and short straight hole combined slot blasting charging structure for small-section tunnels according to claim 1 is characterized in that: The delay error of the electronic detonator is 0.1-0.5 milliseconds.

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