Small-section tunnel drilling and blasting charging structure

Abstract

A small-section tunnel drilling and blasting charging structure comprises cut holes, a large-angle oblique cut is adopted, and the four cut holes are distributed in the two sides of the center line of a tunnel in a rectangular shape; hole expanding is conducted, large-angle oblique hole drilling is adopted, and the eight hole expanding holes are located in the outer side of the slotting hole; the depth of a blasthole of the slotting hole is 1.8-2.2 m, and the depth of the hole expanding hole is 2.7-2.8 m; through the design of the oblique cutting hole, resonance blasting is carried out through the electronic detonator, and the arrangement of the blast hole is combined with the charging structure of the long-delay emptying groove cavity, so that the drilling and blasting technical scheme of the system is formed. The beneficial effects of the utility model are that: through blasthole resonance rock breaking and long time delay groove cavity emptying, the blasthole depth is increased from 1.8-2.0 m to 2.7-2.8 m, 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 the field of tunnel blasting technology, and relates to a drilling and charging structure for a small-section tunnel. Background Technique

[0002] The International Tunneling Association classifies tunnels with a cross-sectional area of 3.0 - 10.0 m 2 as small-section tunnels. When small-section tunnels are constructed by drilling and blasting, there are two types of cut methods: parallel hole cut and inclined hole cut. The parallel hole cut has high requirements for drilling technology and accuracy, and it is not easy for on-site workers to master; the inclined hole cut has relatively lower requirements and is commonly used on-site. When small-section tunnels are blasted with inclined hole cut, the hole depth is 1.8 - 2.2 m, and the blasting advance is between 1.5 - 2.0 m. After the hole depth is greater than 2.2 m, the remaining hole depth is relatively large. The single-cycle blasting advance of small-section tunnels is small, and the tunneling efficiency is low, which cannot meet the needs of current social infrastructure construction.

[0003] With the increasing number and scale of tunnel excavations, especially in small-section tunnels during tunnel tunneling construction using the drill-and-blast method, due to the limitation of the working space, the delay of the tunnel construction period caused by the tunnel advance problem, and the potential safety hazards caused by the damage of the tunnel surrounding rock under the intense action of blasting loads. Safe, economical, and efficient tunnel excavation methods have received increasing attention. Therefore, studying a reasonable hole layout method and blasting parameters to improve the blasting advance of small-section tunnels plays an important role in alleviating social demands, reducing the working cycle of workers, and production risks. Content of the Utility Model

[0004] In view of this, the utility model provides a blasting technology for small-section tunnel inclined hole cut - resonance rock breaking - long-delay emptying of the cavity - long advance electronic detonators. To increase the tunneling speed of the tunnel, it is necessary to increase the hole length. During cut blasting, as the hole depth increases, the clamping effect of the rock increases. When the hole length increases to a certain depth, the rock cannot be thrown out exactly. At this time, the distance from the center of the explosive charge to the free face is called the minimum resistance line W as Figure 1 shown.

[0005] Generally, the direction of the minimum resistance line is considered to be the direction with the least resistance to the particle motion of the rock. Whether the rock can be detached from the rock mass and produce a throwing effect after being affected by the explosion depends on another important parameter Wc, the critical minimum resistance line. The critical minimum resistance line represents that the rock has reached the limit value of elastic deformation, and beyond this value, the rock will undergo brittle failure. When W < Wc, the rock will form a blasting funnel under the action of the explosion; when W > Wc, the damage to the rock by the explosion is limited inside and will not be manifested near the free face. Therefore, the length of the first-stage cut holes in this patent is 1.6 m, and the distance from the center of the explosive charge to the free face is 0.8 m - 1 m.

[0006] When explosives explode in the slot hole, the first is the high temperature and high pressure generated at the moment of the explosion, which forms an air shock wave in the air between the explosives and the blasthole wall, and instantly acts on the rock, generating a shock wave that propagates at supersonic speed in the rock and exerts a strong impact compression effect on the rock, causing the rock around the explosive package to be extremely crushed to form a crushed area. Although this range is very small, it consumes most of the energy of the shock wave, causing the shock wave on the interface of the crushing area to decay into a compressive stress wave. After the compressive stress wave continues to propagate radially in the rock, it will produce compressive stress and compression deformation in the radial direction of the hole wall, and tensile stress and tensile deformation in the tangential direction; since the tensile strength of the rock is 1 / 10 to 1 / 50 of its compressive strength, when the tangential tensile stress is greater than 1 / 10 to 1 / 50 of the tensile strength of the rock, the rock is broken at this location, forming a radial crack that penetrates the crushing area. At this time, under the action of shock waves and stress waves, the rock is strongly compressed and accumulates a part of the elastic deformation energy.

[0007] When the cavity in the crushing zone is formed, radial cracks open, and the pressure drops rapidly to a certain level, the elastic deformation energy that was originally accumulated in the compression process of the rock around the explosive package is released and transformed into an unloading wave, forming a centripetal tensile stress opposite to the compressive stress wave, causing the rock particles to produce reverse radial movement. When this centripetal tensile stress is greater than the tensile strength of the rock, the rock is broken at that location to form annular cracks. While radial cracks and annular cracks are formed, shear cracks may also be formed as a result of the action of radial stress and tangential stress. Under the action of stress waves, initial cracks are formed in the rock, and then the expansion, extrusion, and splitting of the detonation gas promote the extension and expansion of the cracks. The crack expansion can only be stopped when the stress wave and the detonation gas decay to a certain extent. Ultimately, the rock mass around the blasthole can be divided into crushing zone, crushing zone, and elastic zone according to the degree of damage. Figure 2 shown.

[0008] When a single blast hole is detonated in the rock mass, the radius of the crushing zone and the crushing zone can be calculated by the following formula:

[0009]

[0010] Where: r a is the radius of the blast hole; r b is the cavity radius; r c 、r f is the radius of the crushing zone and the radius of the crushing zone; ρ r , μ are the density and Poisson's ratio of the rock mass respectively; c p is the longitudinal wave velocity; c , σ t are the uniaxial compressive strength and tensile strength of the rock mass respectively; σ * is the compressive strength of rock mass under multi-directional stress conditions; β is the load propagation attenuation index in the stress wave zone.

[0011] The specific drilling and blasting charge structure of this application is as follows:

[0012] A small-section tunnel drilling and blasting charging structure, comprising:

[0013] The slotting holes are cut by large-angle oblique holes, and the four slotting holes are distributed in rectangular shapes on both sides of the tunnel centerline; the expansion holes are drilled by large-angle oblique holes, and the eight expansion holes are located outside the slotting holes; the blasthole depth of the slotting holes is 1.8 to 2.2 m, and the depth of the expansion holes is 2.7 to 2.8 m;

[0014] The outer side of the expanded slot hole is provided with a side collapse hole, and the upper part of the cut slot hole is provided with two rows of collapse holes, namely, a first upper collapse hole and a second upper collapse hole, and the second upper collapse hole is located above the first upper collapse hole;

[0015] 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;

[0016] The blasthole depths of the side cave-in holes, the first upper cave-in holes, the second upper cave-in holes, the bottom plate holes and the peripheral holes are all 2.7 to 2.8 m;

[0017] The explosives are charged in the blast holes drilled on the drilling and blasting section, and the explosives are all charged with electronic detonators;

[0018] A delay is set for the electronic detonator in each blasthole; wherein the groove holes are uniformly set to 0 milliseconds, the slot expansion holes are uniformly set to 200 milliseconds, the side collapse holes are uniformly set to 400 milliseconds, the first upper collapse holes are uniformly set to 600 milliseconds, the second upper collapse holes are uniformly set to 800 milliseconds, the bottom plate holes are uniformly set to 1000 milliseconds, and the peripheral holes are uniformly set to 1200 milliseconds.

[0019] Furthermore, 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.

[0020] Furthermore, the vertical spacing of the cutout holes is 50 cm, and the horizontal spacing is 140 cm; the expanded slot holes are arranged vertically with a vertical spacing of 40 cm, and the spacing between the expanded slot holes and the cutout holes is 20 cm.

[0021] 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 30 cm.

[0022] Furthermore, the charge radius is 42 mm.

[0023] Furthermore, the included angle between the slotting hole and the drilling and blasting excavation section is about 70°, and the included angle between the slot expansion hole and the drilling and blasting excavation section is about 75°.

[0024] Furthermore, the delay error of the electronic detonator is 0.1-0.5 milliseconds.

[0025] The utility model has the following technical effects:

[0026] The utility model increases the blasthole depth from 1.8-2.0m to 2.7-2.8m and the blasting footage from 1.8-2.0m to more than 2.5m by blasthole resonance rock breaking and long-delay emptying of the slot cavity. The specific drilling and blasting mechanism is as follows: 4 slot holes are detonated simultaneously at 0ms. When non-electronic detonators are used, the error of 0-12.5ms cannot form resonance, the rock breaking effect is poor, and the residual hole depth is 0.2m. When electronic detonators are used for simultaneous detonation, the error is 0.1-0.5ms, which can form a good resonance effect, good crushing effect, and small residual hole depth. The time required for the cracks generated 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-facing surface for the subsequent blastholes, the delay interval is 200ms. At 200ms, the broken rock has been completely ejected to form a groove cavity with a depth of 1.6m. At this time, the 8 second-stage expansion groove holes are detonated simultaneously. Similarly, the delay time of non-electronic detonators is 50ms, with an error of 0-12.5ms, and resonance cannot be formed. On the basis of a deep residual hole after a blast, the rock cannot be completely ejected and a deeper groove cavity cannot be formed. The delay of electronic detonators is 200ms, with an error of 0.1-0.5ms. When detonated, the rock blasted from the front blasthole has been completely ejected to form a cavity. The blastholes are detonated simultaneously to produce resonance, and the rock breaking effect is good. , leaving a small residual hole depth, at 400ms, the broken rock in the expanded slot hole has been completely thrown out to form a slot cavity with a depth of 2.7m, at this time, 6 three-stage side collapse holes are detonated simultaneously for resonance rock breaking; at 600ms, the rock in the lower half of the side collapse hole heading face is thrown out to form a slot cavity with a depth of 2.7m, at this time, 3 four-stage upper collapse holes are detonated simultaneously for resonance rock breaking; at 800ms, the upper 3 collapse holes throw out all the rocks, at this time, 2 five-stage upper collapse holes are detonated simultaneously for resonance rock breaking; at 1000ms, the upper 2 collapse holes throw out all the rocks, and 5 bottom plate holes are detonated simultaneously for rock breaking; at 1200ms, 15 peripheral holes are detonated simultaneously to form a relatively smooth contour surface, and the blasting footage can reach more than 2.5m. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the minimum resistance line W.

[0028] Figure 2 It is a schematic diagram showing that the rock mass around the blasthole is divided into crushing zone, broken zone and elastic zone according to the degree of destruction.

[0029] Figure 3 It is a blasthole arrangement diagram of the utility model.

[0030] Figure 4 It is a schematic diagram of the charging structure of a section of the slot hole.

[0031] Figure 5 It is a schematic diagram of the envelope of the crushing zone formed by each blast hole. DETAILED DESCRIPTION

[0032] 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.

[0033] In actual projects, the radius of the crushing zone is 3-5 times the radius of the charge, and the radius of the crushing zone is 10-15 times the radius of the charge. Figure 3 As shown, the charge radius is 42mm, the slotting holes are cut with large angles, and the four slotting holes are rectangularly distributed on both sides of the tunnel centerline. The slot expansion holes are drilled with large angles, and the eight blast holes are located outside the slotting holes. The caving holes are located on the top of the slotting holes and outside the slot expansion holes. The peripheral holes and the bottom plate holes are arranged along the contour edge of the cross-section area.

[0034] The charging structure of the slot hole is as follows: Figure 4 As shown in the figure, four blast holes were detonated simultaneously. The rock breaking mechanism adopts the theory of the combined effect of explosion stress wave and explosion gas. That is, the explosion stress wave first damages the rock to form various cracks and fissures. The distance between adjacent blast holes in the center section of the explosive package is 0.5m, and the radius of the crushing zone is 0.32m. The crushing zone envelope formed by each blast hole is as follows: Figure 5 As shown in the figure, the gas wedge effect of the explosive gas further expands the cracks inside the rock, and finally the cracks in the four blast holes are interconnected, causing the rock to be completely destroyed. At the same time, a large amount of explosive gas continues to expand, bulging, crushing, and throwing the surface of the rock and other media in the direction of the minimum resistance line, and finally forming an inverted cone pit, namely the blasting funnel.

[0035] The specific drilling and blasting charge structure is as follows:

[0036] A small-section tunnel drilling and blasting charging structure, comprising:

[0037] The slotting holes 1 are cut by using a large angle oblique eye, and the four slotting holes 1 are distributed in a rectangular shape on both sides of the tunnel centerline; the expansion holes 2 are drilled by using a large angle oblique eye, and the eight expansion holes 2 are located outside the slotting holes 1; the blasthole depth of the slotting holes 1 is 1.8 to 2.2 m, and the depth of the expansion holes 2 is 2.7 to 2.8 m;

[0038] The outer side of the expanded slot hole 2 is provided with a side collapse hole 3, and the upper part of the cut slot hole 1 is provided with two rows of collapse holes 3, which are first upper collapse holes 4 and second upper collapse holes 5, respectively, and the second upper collapse holes 5 are located above the first upper collapse holes 4;

[0039] A bottom plate hole 6 and a peripheral hole 7 are arranged along the contour edge of the cross-section area, and the bottom plate hole 6 is located at the lower part of the groove hole 1;

[0040] The blasthole depths of the side cave-in hole 3, the first upper cave-in hole 4, the second upper cave-in hole 5, the bottom plate hole 6 and the peripheral hole 7 are all 2.7 to 2.8 m;

[0041] The explosives are charged in the blast holes drilled on the drilling and blasting section, and the explosives are all charged with electronic detonators;

[0042] A delay is set for the electronic detonator in each blasthole; wherein the groove hole 1 is uniformly set to 0 milliseconds, the expanded slot hole 2 is uniformly set to 200 milliseconds, the side collapse hole 3 is uniformly set to 400 milliseconds, the first upper collapse hole 4 is uniformly set to 600 milliseconds, the second upper collapse hole 5 is uniformly set to 800 milliseconds, the bottom plate hole 6 is uniformly set to 1000 milliseconds, and the peripheral hole 7 is uniformly set to 1200 milliseconds.

[0043] Furthermore, the number of the side collapse holes 3 is 6, the number of the first upper collapse holes 4 is 3, the number of the second upper collapse holes 5 is 2, the number of the bottom plate holes 6 is 5, and the number of the peripheral holes 7 is 15.

[0044] Furthermore, the vertical spacing of the cutout holes 1 is 50 cm, and the horizontal spacing is 140 cm; the expanded slot holes 2 are arranged vertically with a vertical spacing of 40 cm, and the spacing between the expanded slot holes 2 and the cutout holes 1 is 20 cm.

[0045] Furthermore, the side collapse holes 3 are arranged vertically, three on each side, and the spacing between the side collapse holes 3 and the expansion slot holes 2 is 30 cm.

[0046] Furthermore, the charge radius is 42 mm.

[0047] Furthermore, the included angle between the slotting hole 1 and the drilling and blasting excavation section is about 70°, and the included angle between the slot expansion hole 2 and the drilling and blasting excavation section is about 75°.

[0048] Furthermore, the delay error of the electronic detonator is 0.1-0.5 milliseconds.

[0049] 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 drilling and blasting charging structure, characterized in that: include: The slotting holes are cut by large-angle oblique holes, and the four slotting holes are distributed in rectangular shapes on both sides of the tunnel centerline; the expansion holes are drilled by large-angle oblique holes, and the eight expansion holes are located outside the slotting holes; the blasthole depth of the slotting holes is 1.8 to 2.2 m, and the depth of the expansion holes is 2.7 to 2.8 m; The outer side of the expanded slot hole is provided with a side collapse hole, and the upper part of the cut slot hole is provided with two rows of collapse holes, namely, a first upper collapse hole and a second upper collapse hole, and 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 side cave-in holes, the first upper cave-in holes, the second upper cave-in holes, the bottom plate holes and the peripheral holes are all 2.7 to 2.8 m; 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 groove holes are uniformly set to 0 milliseconds, the slot expansion holes are uniformly set to 200 milliseconds, the side collapse holes are uniformly set to 400 milliseconds, the first upper collapse holes are uniformly set to 600 milliseconds, the second upper collapse holes are uniformly set to 800 milliseconds, the bottom plate holes are uniformly set to 1000 milliseconds, and the peripheral holes are uniformly set to 1200 milliseconds.

2. A small-section tunnel drilling and blasting charging structure according to claim 1, characterized in that: There are 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 drilling and blasting charging structure according to claim 2, characterized in that: The vertical spacing between the cutout holes is 50 cm, and the horizontal spacing is 140 cm; the expanded slot holes are arranged vertically with a vertical spacing of 40 cm, and the spacing between the expanded slot holes and the cutout holes is 20 cm.

4. A small-section tunnel drilling and 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 30 cm.

5. A small-section tunnel drilling and blasting charging structure according to claim 1, characterized in that: The charging radius is 42mm.

6. A small-section tunnel drilling and blasting charging structure according to claim 1, characterized in that: The included angle between the slotting hole and the drilling and blasting excavation section is about 70°, and the included angle between the slot expansion hole and the drilling and blasting excavation section is about 75°.

7. A small-section tunnel drilling and blasting charging structure according to claim 1, characterized in that: The delay error of the electronic detonator is 0.1-0.5 milliseconds.

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