Multi-point concentrated energy micro-perforation blasting method in blasthole and its installation structure

Abstract

The present invention discloses a method for multi-point energy-gathering micro-perforation blasting in a blasthole and its installation structure, the steps of which include: (1) utilizing the plasticity of explosive column, inserting 1 to 6 energy-gathering covers with a sharp cone-shaped top and a pressure edge at the bottom into the column from the side of the column through the sharp cone-shaped structure at the top, until the pressure edge at the bottom of the energy-gathering cover faces outward and is close to the surface of the column, and then fixing the energy-gathering cover to the column to complete the production of the energy-gathering package, and ensuring that all the energy-gathering covers are arranged on the same side of the column; (2) according to actual needs, several energy-gathering packages produced according to step (1) are put into the blasthole, and when being put in, it is ensured that the energy-gathering holes of the energy-gathering covers on the energy-gathering packages are radially facing the air surface, and there is a clearance fit between the energy-gathering packages and the blasthole; (3) blasting is performed according to the detonation networking steps of conventional medium-deep hole blasting. The present invention reduces the number of holes drilled and the unit consumption of explosives, improves the blasting efficiency, and significantly saves the drilling and blasting costs.

Description

Technical Field

[0001] The invention belongs to the field of blasting construction, and specifically relates to a method for multi-point energy-focused micro-perforation blasting in a blasthole and an installation structure thereof, and is particularly suitable for medium-deep hole blasting construction. Background Art

[0002] The energy released when the explosive explodes in the rock mass is transmitted to the rock through the blasting stress wave and the expansion pressure of the detonation gas, causing the rock to break. However, the energy actually used to break the rock only accounts for a very small part of the energy released by the explosive. Most of the energy is consumed in useless work, such as heat conduction, heat radiation, excessive crushing and plastic deformation of the medium during the explosion process, and some invalid mechanical work is consumed in the vibration and throwing of the rock and the formation of air shock waves in the air. When throwing blasting is used, the useful work used for blasting and breaking only accounts for 5% to 7% of the total energy. Even if loose blasting is used, the energy utilization rate will not exceed 20%. Therefore, improving the utilization rate of explosive explosion energy is an important factor in effectively breaking rocks, improving blasting effects and improving economic benefits, and it is also the unremitting pursuit of blasting engineering and technical personnel.

[0003] For many years, the energy-gathering principle of explosive explosion and the effects it produces were only used for military purposes in armor-piercing shells. In recent years, it has gradually been transferred to civilian use and can be included in the scope of engineering blasting. For example, the energy-gathering effect is used to drill holes in frozen soil, break ice and remove icicles, perforate the steel outlet of steelmaking open-hearth furnaces, perforate oil wells or eliminate drilling faults and cut steel plates, or use energy-gathering tubes for pre-splitting blasting and smooth blasting to form a smooth and complete excavation contour surface.

[0004] In 2006, China University of Mining and Technology applied for a national patent "A Multi-directional Energy-gathering Blasting Device" (ZL200620074521.2). This utility model discloses a multi-directional energy-gathering blasting device, which aims to reduce the number of holes drilled and the unit consumption of explosives. It includes a casing with multiple protrusions evenly distributed on the inner wall, and a special-shaped energy-gathering bag is arranged in the casing, which is tightly matched with the inner wall of the protrusions and squeezed. The energy-gathering hole for multi-directional energy-gathering blasting is formed by the protrusions. During the explosion, the energy of the explosives converges along the direction of the energy-gathering hole to form a high-speed jet, so that multiple radial cracks are preferentially formed around the blasthole, and then rapidly expand under the action of the explosive gas, cutting the rock into fragments. This patent has been applied for more than ten years, and no related application reports have been seen on the Internet so far. There are four main reasons for this. First, the construction process is complicated. Second, the casing greatly increases the blasting cost. Third, the number of energy-gathering holes is limited by space and it is impossible to set a large number of them. Fourth, similar to slot blasting, multiple radial cracks are formed around the blasthole first, and the explosion energy is introduced into the pre-cracks, which inhibits the formation of other random cracks and greatly increases the rate of blasting large blocks. This method can be used to obtain large blocks of stone, but it cannot effectively reduce the unit consumption of explosives.

[0005] In addition, in recent years, water medium energy conversion blasting method has emerged, which intends to improve the energy utilization rate of explosives while reducing the harmful effects of blasting. The steps of this method include first installing water medium and explosives with a mass ratio greater than or equal to the optimal value in the explosive charging cavity of the blasting medium, and isolating the explosives and water medium from each other, and then detonating the explosives installed in the explosive charging cavity. This method has only been tested in a few mines at home and abroad, and there is no trend of universal promotion. The reasons are mainly as follows: First, this method is mainly effective in reducing blasting dust, but not obvious in reducing the unit consumption of explosives. Second, the water medium added in this method is isolated from the explosives in sections, and the direct contact area is very small. After the explosion of the explosives, the water medium absorbs energy and breaks the chemical bonds to decompose into H2 and O2. There is no basis for the statement. Moreover, water decomposition is endothermic, which reduces the temperature and pressure of the "explosion thermodynamic system" in the blasthole after the explosion of the explosives. Third, if the water bag is placed at the bottom of the blasthole, the rate of large blocks at the bottom will inevitably increase. If the water bag is placed at the top of the blasthole, it is equivalent to increasing the blockage length, which will inevitably increase the rate of large blocks at the top. If the water bag is placed in the middle of the blasthole, it will inevitably form a segmented charge, requiring an increase in the number of detonators or the use of detonating cords, increasing the blasting cost. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method and installation structure for multi-point energy-focused micro-perforation blasting in a blasthole with less blasting smoke and dust, which can improve the effective utilization rate of explosive energy, improve the blasting effect of explosives on blasting media, reduce blasting hazards, and reduce blasting smoke.

[0007] The present invention is achieved through the following technical solutions:

[0008] The method of multi-point energy-gathering micro-perforation blasting in a blasthole comprises the following steps:

[0009] (1) Using the plasticity of the explosive column, 1 to 6 energy-gathering covers with a pointed cone-shaped top and a pressure edge at the bottom are inserted into the charge column from the side through the pointed cone-shaped structure at the top until the pressure edge at the bottom of the energy-gathering cover faces outward and is in close contact with the surface of the charge column. Then, the energy-gathering cover is fixed to the charge column to complete the production of the shaped charge. It is ensured that all the energy-gathering covers are arranged on the same side of the charge column.

[0010] (2) according to actual needs, a plurality of shaped charges prepared according to step (1) are placed into the blast hole, and when placing, the shaped charge holes of the shaped caps on the shaped charges are ensured to be radially oriented toward the air surface, and there is a clearance fit between the shaped charges and the blast hole; in the blast hole, ordinary explosive charges may or may not be arranged between the shaped charges according to actual needs;

[0011] (3) Blasting is carried out according to the detonation networking steps of conventional medium-deep hole blasting.

[0012] Preferably, the drug column is a cylindrical drug column.

[0013] The explosive column includes an outer layer that wraps the explosive material, but the explosive itself has good plasticity, so a focusing hood with a pointed cone-shaped top and a pressure edge at the bottom can be inserted into it. Specifically, the top can be aligned with the center of the cylindrical column, perpendicular to the axis of the column, and the focusing hood can be inserted into the column with the pressure edge facing outward and close to the column. Then the focusing hood is fixed to the column to complete the production of the shaped charge. This process can be produced on-site or prefabricated in a factory.

[0014] Preferably, in step (1), the explosive in the charge column is a gelled emulsion explosive, a water gel explosive or a slurry explosive.

[0015] Preferably, in step (1), the energy focusing cover is adhered and fixed to the cylindrical drug column using transparent tape.

[0016] Preferably, the cone apex angle α of the energy-gathering hood is 30° to 70°. This range is selected because when the cone apex angle α is less than 30°, the perforation performance is very unstable. When the cone apex angle α is between 30° and 70°, the jet has sufficient mass and speed to achieve a stable perforation effect and a good perforation effect. When the cone apex angle α is greater than 70°, the perforation depth decreases rapidly, but the fragmentation range increases. Therefore, the cone angle selected here is to maximize the blasting purpose of the energy-gathering micro-perforation.

[0017] Preferably, the energy focusing cover is made of metal, glass, ceramic or PVC.

[0018] Preferably, the generatrix of the energy concentrating cover is a straight line, a broken line or an arc.

[0019] Preferably, the width of the pressed edge at the bottom of the energy focusing cover is 2 mm to 5 mm.

[0020] Preferably, the energy focusing cover has a uniform wall thickness of 1 to 3 mm.

[0021] Preferably, the bottom circle diameter of the energy-gathering cover is as follows: Adaptive selection is made, where α is the cone apex angle and D is the shaped charge diameter. The selection of d here is derived from the deformed shaped charge shape and geometric parameter diagram shown in Figure 11-5a in Chapter 11.1 shaped charge blasting in "Theory and Technology of Engineering Blasting" compiled by the China Engineering Blasting Association. Specifically, it is derived by inscribing the projection rectangle of its charge column with the cross-sectional circle of the cylindrical shaped charge, so that the perforation depth of the shaped charge is most matched with the charge diameter and height. Because, in this entire shaped charge, the explosives that participate in the formation of the shaped charge jet are only the explosive layer within a certain thickness close to the charge cap. This layer of explosives is called the effective explosive layer. The structure of this shaped charge cap can make full use of the diameter of the explosive and maximize the effective explosive layer. In the book, when determining the structural shape of the shaped charge, in order to minimize the charge weight and achieve the ideal rock-breaking effect, the cylindrical shaped charge is simplified into a quasi-truncated cone-shaped shaped charge. The parameter relationship between the bottom diameter of the shaped hood, the charge column diameter, the charge column height, and the shaped hood cone apex angle is given by the empirical formula. The bottom diameter of the shaped hood is only related to the diameter of the charge column. The shaped hood in the book is located on the bottom surface of the cylindrical or quasi-truncated cone column, and the usage and use scenarios are different. The shaped hood of the present invention is located on the side of the cylindrical shaped charge and is used for deep hole blasting in rocks. According to the projection relationship, the upper limit value of the bottom diameter of the shaped hood of the present invention is derived from the Pythagorean theorem. It is a function of the charge column diameter and the cone apex angle, which is significantly different from the formula in the book.

[0022] Preferably, according to the firmness of the blasting rock, the size and specification of the shaped charge and the position of the shaped charge in the blast hole, the number of shaped covers placed on each shaped charge is 1 to 4.

[0023] Preferably, in order to maximize the rock-breaking effect of the energy-gathering hood, in the step (2), the energy-gathering holes of the energy-gathering hood are directed radially toward the free surface. More preferably, when the energy-gathering holes of the energy-gathering hood are directed radially, the radiation angle β is 50° to 110°, which is the main movement direction of broken rocks during blasting.

[0024] Preferably, in step (2), the enhanced micro-perforation blasting method is used at the bottom of the blasthole, and the ordinary micro-perforation blasting method is used in the middle and upper part, that is, the number density of the energy-gathering shields near the bottom of the blasthole is arranged to be greater than the number density in the middle and upper part, so as to solve the problem that the root sill is easily left at the bottom of the blasthole after the vertical medium-deep hole blasting. Because, in the vertical medium-deep hole blasting, the bottom rock is in a bidirectional or multi-directional stress state, and the chassis resistance line is large, the root sill often remains at the bottom of the blasthole after blasting, and the root sill needs secondary drilling and blasting treatment or mechanical treatment, which increases the blasting cost and affects the construction progress. In conventional blasting, the position of the charge center is often reduced by increasing the super depth to overcome the resistance at the bottom of the step and reduce the root bottom. This practice increases the drilling amount and charge amount, thereby greatly increasing the blasting cost, and cannot completely eliminate the root sill phenomenon. By combining the present invention, the enhanced micro-perforation blasting method can be used at the bottom of the blasthole, and the ordinary micro-perforation blasting method can be used in the middle and upper part, so as to achieve the purpose of more reasonable utilization of blasting energy.

[0025] The invention also discloses an energy gathering cover, wherein the top of the energy gathering cover is in a pointed cone shape and the bottom is provided with a pressing edge.

[0026] Preferably, the cone apex angle α of the energy focusing cover is 30° to 70°.

[0027] Preferably, the energy focusing cover is made of metal, glass, ceramic or PVC.

[0028] Preferably, the generatrix of the energy concentrating cover is a straight line, a broken line or an arc.

[0029] Preferably, the width of the pressed edge at the bottom of the energy focusing cover is 2 mm to 5 mm.

[0030] Preferably, the energy focusing cover has a uniform wall thickness of 1 to 3 mm.

[0031] Preferably, the bottom circle diameter of the energy-gathering cover is as follows: Make adaptive selection, where α is the cone apex angle and D is the drug package diameter.

[0032] The present invention also discloses an installation structure for multi-point energy-focused micro-perforation blasting in the above-mentioned blasthole, including a blasthole and an explosive assembly arranged in the blasthole with a gap fit, the explosive assembly comprising a plurality of mutually contacting medicine bags, the medicine bags being a cylindrical medicine column structure, a plurality of energy-focused covers being inserted on at least some of the medicine bags, the top of the energy-focused cover being a pointed cone, the bottom being provided with an outward pressing edge, the top of the energy-focused cover being inserted into the cylindrical medicine column, and the pressing edge being fitted on the outer surface of the cylindrical medicine column.

[0033] Preferably, the energy-gathering shields on the shaped charges in the explosive assembly are arranged in a reciprocating or folding arrangement in the blast hole, and the energy-gathering holes of the energy-gathering shields are radiated toward the air surface, and the radiation angle β is 50° to 110°.

[0034] Preferably, a filling section is provided at the upper part of the blasthole, and the explosive assembly is arranged at the lower part of the filling section. Generally, there is an air gap between the explosive assembly and the blasthole.

[0035] The beneficial effects of the present invention are:

[0036] The method for multi-point energy-focused micro-perforation blasting in a blasthole and the installation structure thereof of the present invention have the following advantages:

[0037] The present invention is based on the mechanism of rock damage mechanics and fracture mechanics, and proposes to use the shaped jet of the shaped cap to first impact multiple radial micro-perforations in the blasthole facing the free surface, and then the explosive gas penetrates into the pores to play the role of gas wedge, generating stress concentration around the micro-perforations. Under the action of static pressure, the cracks formed by the stress wave are further expanded. Since the explosive gas has more penetration space and will not dissipate quickly, the expansion time of the gas is longer, which is more conducive to the crushing of the rock. At the same time, according to the stress wave reflection principle, after the shaped charge explodes, the compression stress wave reaches the free surface and is reflected back from the free surface, becoming a tensile stress wave with completely opposite properties and directions. Since the tensile strength of the rock is much smaller than the compressive strength, this reflected tensile wave can cause the rock to fall and cause the expansion of radial cracks. At the same time, since the energy-gathering hole of the energy-gathering cover is radially directed toward the free surface, the shock wave in the direction of the energy-gathering hole is greatly enhanced, and accordingly, the tensile stress wave reflected by the shock wave after reaching the free surface is also greatly enhanced, thereby causing stronger rock flakes and radial crack expansion. In blasting engineering practice, the method of filling the blasthole with colloidal emulsion explosives is the most widely used. In this method, there is generally an air gap between the cylindrical charge column and the blasthole wall, that is, uncoupled charge. This charging method is extremely unfavorable for blasting hard rocks. The use of the present invention will turn this unfavorable condition into a favorable condition. There are two reasons. One is that the energy-gathering cover converges and collides in the axial direction under the action of the detonation wave, and then focuses and extends to form a normal jet. In the process, an appropriate spatial distance is required, that is, the blast height. Therefore, the gap between the charge column of the uncoupled charge and the hole wall is conducive to enhancing the energy-gathering effect of the energy-gathering cover. Second, because the wave impedance of the No. 2 rock emulsion explosive commonly used in engineering is much smaller than the wave impedance of hard and dense rock. The presence of the energy-gathering cover partially improves the power of the explosive, which is equivalent to locally improving the matching degree between the wave impedance of the explosive and the wave impedance of the rock, so that the explosive transfers more energy to the rock, and the strain value caused in the rock is larger, which should obtain a better blasting effect. In addition, the previous blasting energy-gathering technology is to load explosives into the blasting profile manually or with the help of charging equipment to form an energy-gathering structure. The present invention innovatively goes the other way and uses the energy-gathering cover to directly insert the plasticity of the colloid explosive to form an energy-gathering structure. The operation is simple and the consumables are few. At the same time, due to the extrusion of the energy-gathering cover, the local charge density is increased, the detonation speed is increased, and the energy-gathering effect is better. According to the law of conservation of energy, when using the present invention, although the total energy of the explosive explosion does not change, the presence of the energy-gathering cover greatly optimizes the energy distribution of the explosive explosion on the blasthole wall, thereby improving the effective utilization rate of the explosion energy, correspondingly reducing the harmful effects of the blasting, and reducing the useless work consumed in the rock crushing area. The energy-gathering hood concentrates part of the explosive energy to first form micro-perforations on the borehole wall, creating favorable conditions for the subsequent expansion of the explosive gas.Theoretical analysis and blasting numerical simulation show that the use of the present invention can reduce the unit consumption of explosives by 20% to 30% under the condition of the same blasting medium, reduce blasting vibration by 20% to 25%, reduce the bulk rate by 40% to 45%, and the crushing particle size of the blasting medium is more uniform compared with ordinary blasting, and the concentrated blasting pile is convenient for excavation and transportation operations, so the cost is reduced by 20 to 25%. Therefore, it has the advantages of being able to improve the effective utilization rate of explosive energy, improve the blasting effect of explosives on blasting media, and reduce blasting hazards.

[0038] The implementation method of the present invention is simple and easy to implement, has little difference from the existing various blasting operation construction process steps and has better effects, significantly saves construction costs, is easily accepted by construction units, and is easy to promote and apply.

[0039] The energy-gathering hood in the present invention has a small volume, a simple structure, a simple production process, very few consumables, low cost, and is easy to manage and transport.

[0040] The invention is suitable for all kinds of explosives to blast and break rocks and concrete, and can be used in shallow hole blasting, deep hole blasting, underground blasting, chamber blasting, and underwater blasting. It can be widely promoted and applied in the construction industries such as water conservancy and hydropower, mining, highways, and railways. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] For ease of explanation, the present invention is described in detail with reference to the following specific embodiments and accompanying drawings.

[0042] Figure 1 It is a front view of the energy gathering cover in the embodiment of the present invention;

[0043] Figure 2 is a top view of an energy collecting cover in an embodiment of the present invention;

[0044] Figure 3 for Figure 2 A-A section view;

[0045] Figure 4 It is the plan view of blasthole arrangement on the blasting operation surface;

[0046] Figure 5 for Figure 4 Schematic diagram of the direction of the energy-gathering hole of the middle energy-gathering shield;

[0047] Figure 6 A large-scale drawing of installing one or more shaped shields on a shaped charge;

[0048] Figure 7 This is a diagram of the structure of the return blast hole shaped charge;

[0049] Figure 8 This is a diagram of the structure of a reciprocating blast hole shaped charge;

[0050] Among them, 1-energy-gathering cover, 2-pressure edge, 3-blast hole, 4-air surface on the rock, 5-radiation angle of energy-gathering hole, 6-charge column, 7-transparent tape, 8-filling section, 9-air gap. DETAILED DESCRIPTION

[0051] like Figure 1-8 As shown, the method of multi-point energy-focused micro-perforation blasting in a blasthole comprises the following steps:

[0052] (1) By utilizing the plasticity of the explosive column 6, 1 to 6 energy-gathering covers 1 with a pointed cone-shaped top and a pressure edge 2 at the bottom are inserted into the explosive column 6 from the side through the pointed cone-shaped structure at the top until the pressure edge 2 at the bottom of the energy-gathering cover faces outward and is in close contact with the surface of the explosive column 6. Then, the energy-gathering cover 1 is fixed to the explosive column 6 to complete the production of the shaped charge, and it is ensured that all the energy-gathering covers 1 are arranged on the same side of the explosive column 6.

[0053] (2) according to actual needs, a plurality of shaped charges prepared according to step (1) are placed into the blast hole, and when placing, the shaped charge is ensured to be oriented radially toward the air surface with the shaped cap 1 on the shaped charge, and there is a clearance fit between the shaped charge and the blast hole; in the blast hole, ordinary explosive charges may or may not be arranged between the shaped charges according to actual needs;

[0054] (3) Blasting is carried out according to the detonation networking steps of conventional medium-deep hole blasting.

[0055] By utilizing the plasticity of the explosive column, the energy-gathering cover 1 is inserted into the explosive column 6 and fixed to complete the production of the energy-gathering package. This process can be produced on site or prefabricated in a factory. Then, according to the actual situation, the prepared energy-gathering packages are put into the medium-deep hole blast hole 3 one by one, and the orientation of the energy-gathering hole is roughly evenly distributed within the radiation angle β. Generally, there is a gap fit between the energy-gathering package and the blast hole 3, and the other detonation networking steps are the same as those of conventional medium-deep hole blasting.

[0056] The method is suitable for blasting operations using gelled emulsion explosives, water gel explosives and slurry explosives.

[0057] The explosive in the charge column 6 is a gelled emulsion explosive, a water gel explosive or a slurry explosive.

[0058] The energy-gathering cover 1 is adhered and fixed on the cylindrical charge column 6 by using a transparent tape 7 .

[0059] The cone apex angle α of the energy focusing cover 1 is 30° to 70°.

[0060] The energy collecting cover 1 is made of metal, glass, ceramic or PVC.

[0061] The generatrix of the energy gathering cover 1 is a straight line, a broken line or an arc.

[0062] The width of the bottom edge of the energy gathering cover 1 is 2 mm to 5 mm.

[0063] The energy-gathering cover 1 has a uniform wall thickness of 1 to 3 mm.

[0064] The bottom diameter of the energy-gathering cover 1 is given by the formula Make adaptive selection, where α is the cone apex angle and D is the diameter of the shaped charge.

[0065] According to the firmness of the blasting rock, the size and specification of the shaped charge and the position of the shaped charge in the blast hole, the number of shaped covers 1 placed on each shaped charge is 1 to 4.

[0066] In order to maximize the rock-breaking effect of the energy-gathering hood, the energy-gathering holes of the energy-gathering hood are directed radially toward the air surface, and the radiation angle β of the energy-gathering hole radiation angle 5 is 50°~110°. This direction is the main movement direction of broken rocks during blasting.

[0067] The installation structure for multi-point focused energy micro-perforation blasting in the above-mentioned blasthole includes a blasthole and an explosive assembly arranged in the blasthole with a gap fit, the explosive assembly includes a plurality of mutually contacting powder bags, the focused powder bags are cylindrical powder column structures, and a plurality of focused energy covers are inserted on at least part of the cylindrical powder columns. The top of the focused energy cover is a pointed cone, and the bottom is provided with an outward pressing edge. The top of the focused energy cover is inserted into the cylindrical powder column, and the pressing edge is fitted on the outer surface of the cylindrical powder column.

[0068] See Figure 7 , Figure 8 The energy-gathering shield on the shaped charge in the explosive assembly is arranged in a reciprocating or return arrangement in the blasthole, and the energy-gathering hole of the energy-gathering shield is radially directed toward the free surface 4 on the rock mass, and the radiation angle β is 50° to 110°.

[0069] A filling section 8 is provided at the upper part of the blasthole 3, and the explosive assembly is arranged at the lower part of the filling section. There is an air gap 9 between the explosive assembly and the blasthole wall.

[0070] Embodiment 1

[0071] A quarry uses medium-deep hole step blasting method to quarry. The rock is medium-hard sandstone. The diameter of blasthole 3 is 115mm, the blasthole depth is 8m, and the filling is 3m. The charge column 6 uses No. 2 rock emulsion explosive with a specification of Φ70mm-2000g. Three rows of blastholes are arranged in a plum blossom shape. The blasthole layout plan is as follows: Figure 4 The cone vertex angle α of the energy collecting hood is 60°, and the bottom circle diameter is based on the formula The actual d is 40mm, and the edge width is 5mm. The energy-gathering hole of the energy-gathering cover is oriented in the plane diagram as shown in the figure. Figure 5As shown. A shaped charge of explosive is placed with a shaped cover, and the shaped cover is finally arranged in a folded shape in the blast hole. The shaped charge structure of the blast hole is shown in Figure 7 shown.

[0072] Embodiment 2

[0073] A shaped charge pack is placed with a shaped cover, and the shaped cover is finally arranged in a reciprocating manner in the blast hole. The structure of the shaped charge in the blast hole is shown in the figure below. Figure 8 The remaining conditions are the same as those in Example 1.

[0074] Embodiment three:

[0075] In vertical medium-deep hole blasting, since the bottom rock is in a bidirectional or multi-directional stress state and the chassis resistance line is large, root sills often remain at the bottom of the blasthole after blasting. The root sills need to be processed by secondary drilling and blasting or mechanical treatment, which increases the blasting cost and affects the construction progress. In conventional blasting, the position of the charge center is often lowered by increasing the super-depth to overcome the resistance at the bottom of the step and reduce the remaining root sills. This approach increases the amount of drilling and charging, thereby greatly increasing the blasting cost, and cannot completely eliminate the root sill phenomenon. The combined application of the present invention can use the enhanced micro-perforation blasting method at the bottom of the blasthole, and the ordinary micro-perforation blasting method in the middle and upper parts, that is, the number density of the energy-gathering hoods near the bottom of the blasthole is arranged to be greater than the number density in the middle and upper parts, so as to achieve the purpose of more reasonable use of blasting energy. The arrangement of the energy-gathering hoods is the same as that of Example 1 or Example 2.

[0076] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that are not conceived through creative work should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined in the claims.

Claims

1. Multi-point energy-gathering micro-perforation blasting method in the blast hole, It is characterized in that Steps include: (1) By utilizing the plasticity of the explosive column, 1 to 6 energy-gathering covers with a pointed cone-shaped top and a pressure edge at the bottom are inserted into the charge column from the side through the pointed cone-shaped structure at the top until the pressure edge at the bottom of the energy-gathering cover faces outward and is in close contact with the surface of the charge column. Then, the energy-gathering cover is fixed to the charge column to complete the production of the shaped charge. It is ensured that all the energy-gathering covers are arranged on the same side of the charge column. (2) according to actual needs, a plurality of shaped charges prepared according to step (1) are dropped into the blast hole, and when dropping, the shaped charge holes of the shaped caps on the shaped charges are ensured to be radially oriented toward the air surface, and there is a clearance fit between the shaped charges and the blast hole; in the blast hole, ordinary explosive charges may or may not be arranged between the shaped charges according to actual needs; (3) Blasting is carried out according to the initiation and networking steps of conventional medium- and long-hole blasting; The cone apex angle α of the energy focusing cover is 30° to 70°.

2. The method for multi-point energy-focused micro-perforation blasting in a blasthole according to claim 1, It is characterized in that The explosive in the charge column is a gelled emulsion explosive, a water gel explosive or a slurry explosive.

3. The method for multi-point focused micro-perforation blasting in a blasthole according to claim 1, It is characterized in that The reference formula for the bottom circle diameter of the energy-gathering hood is Make adaptive selection, where α is the cone apex angle, D is the diameter of the shaped charge, and the bottom circle is the circle corresponding to the cone apex angle of the shaped charge cover.

4. The method for multi-point focused micro-perforation blasting in a blasthole according to claim 1, It is characterized in that In the step (2), it is ensured that the energy-gathering holes of the energy-gathering cover on the shaped charge are radiated toward the air-facing surface, and the radiation angle β is 50° to 110°.

5. The method for multi-point focused micro-perforation blasting in a blasthole according to claim 1, It is characterized in that In the step (2), the enhanced micro-perforation blasting method is used at the bottom of the blasthole, and the ordinary micro-perforation blasting method is used in the middle and upper parts, that is, the number density of the energy-gathering shields near the bottom of the blasthole is arranged to be greater than the number density in the middle and upper parts, so as to solve the problem of residual roots at the bottom of the blasthole after vertical medium-deep hole blasting.

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