Blasting structure, blasting method and shoveling and loading method after blasting for bounded slope steps of open stope

Abstract

The invention discloses a blasting structure, a blasting method and a shoveling and loading method after blasting of an open stope bounded side slope, the front side and the rear side of the blasting structure are a free surface and an upper step slope angle line respectively, the blasting structure comprises a pre-bounded blasting area and a bounded side slope blasting area, and the junction of the two blasting areas is a boundary line; a plurality of rows of first blast holes with the elevation angle of 90 degrees are formed in the pre-bounded blasting area, the distance between the free face and the adjacent first blast hole is 4 m, and the distance between the boundary line and the adjacent first blast hole is 5 m; four rows of blast holes are sequentially formed in the boundary-reaching side slope blasting area at intervals and include main blasting holes with the elevation angle being 90 degrees, buffering holes, auxiliary holes and pre-splitting holes with the elevation angle being 60 degrees, the distance between the main blasting holes and the boundary line is 4 m, a safety platform is arranged on the rear sides of the pre-splitting holes, and the distance between the pre-splitting holes and the slope angle line of the upper step is not smaller than 6 m. Good conditions are created for formation of a final boundary slope, meanwhile, interference to the stability of surrounding rock masses is reduced to the maximum extent, and potential safety hazards caused by over-explosion or under-explosion are avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of open pit side slope step blasting, and in particular relates to a blasting structure from an open pit to a boundary side slope, a blasting method and a shoveling method after blasting. Background Art

[0002] The slope of the open-pit mine is one of the major hidden dangers in the safe production of open-pit mines. The stability of the slope of the open-pit mine is an important prerequisite directly related to the normal production of the mine. The recovery and management of the critical slope of the open-pit mine is an indispensable part of mining engineering and technical work. During the long-term blasting and shoveling process in open-pit mines, the side slopes of the mines are often in an unreached state for a long time. In this state, if the blasting energy is too large or the aftershock is too large, the rock will be over-broken, forming a safety hazard, making the slope unstable and affecting the safety of operating equipment and personnel. Insufficient blasting will also cause inconvenience in shoveling, and is not conducive to the parameter design of the standard steps of the slope. In addition, traditional deep hole blasting often has more prominent problems such as over-excavation and under-excavation. The excavation interface is rough and uneven, which often causes poor appearance quality of the slope and even affects the stability of the excavation interface, inducing engineering accidents such as landslides and landslides. The reason is that the crushing and loosening range of the blasting hole explosion in the blasting area invades the non-excavation area, causing local damage to the rock on the other side of the excavation interface. At the same time, how to ensure the integrity of the half-hole wall during the shoveling process after blasting is also an urgent problem to be solved in the mining process of the mine. Therefore, the unbounded slopes not only limit the effective mining area and reduce the amount of mineable ore, which in turn affects mining efficiency and output, leading to increased mining costs, but also cause some mineral resources to be temporarily unable to be economically and efficiently mined, affecting the overall resource utilization and economic benefits of the mine. Summary of the invention

[0003] The present invention provides a blasting structure, a blasting method and a post-blasting shoveling method for an open-pit mine to a boundary slope. The invention adopts a refined blasting technology, from pre-boundary blasting to controlled blasting of the boundary slope, to create good conditions for the formation of the final boundary slope, while minimizing the interference with the stability of the surrounding rock mass, ensuring that the slope shape and stability strictly follow the design specifications, and avoiding the safety hazards caused by over-blasting or under-blasting.

[0004] The technical solutions to solve the technical problems are as follows:

[0005] According to one aspect of the present application, a blasting structure for a boundary slope step in an open-pit mine is provided, which includes a pre-boundary blasting area and a boundary slope blasting area arranged in sequence, the front edge of the pre-boundary blasting area and the rear edge of the boundary slope blasting area are a free surface and a slope angle line of a previous step, respectively, and the junction of the two is a junction line; the pre-boundary blasting area is provided with several rows of first blastholes with an elevation angle of 90°, the free surface is 4m away from its adjacent first blasthole, and the boundary line is 5m away from its adjacent first blasthole; the boundary slope blasting area is provided with four rows of blastholes arranged in sequence at intervals, namely: a main blasting hole, a buffer hole and an auxiliary hole with an elevation angle of 90° and a pre-crack hole with an elevation angle of 60°, the main blasting hole is 4m away from the junction line, the rear side of the pre-crack hole is arranged as a safety platform, and the pre-crack hole is not less than 6m away from the slope angle line of the previous step.

[0006] Furthermore, if there are more than one row of first blast holes, the row spacing between two adjacent rows of first blast holes is 6m, and the hole spacing between two adjacent blast holes in each row of first blast holes is 7-8m; the spacing between two adjacent blast holes in each row of the main blast holes, buffer holes and auxiliary holes is 5-6m, and the spacing between two adjacent blast holes in each row of the pre-cracking holes is 1.5-2m; the row spacing between the buffer holes and the main blast holes and the auxiliary holes is 4.5m and 2.8m respectively, and the row spacing between the auxiliary holes and the pre-cracking holes is 5m.

[0007] Furthermore, the first blasthole comprises, from bottom to top, a lower emulsion explosive section provided with lower emulsion explosive, a middle spacing section, a middle emulsion explosive section provided with middle emulsion explosive, and a section provided with hole slag and an upper plugging section; the length of the lower emulsion explosive section is greater than that of the middle emulsion explosive and the middle spacing section; the lower emulsion explosive section and the middle emulsion explosive are connected by a first detonating cord, and detonators are respectively provided inside the two detonators, and the first detonating cords are respectively connected to the two detonators.

[0008] Furthermore, the main blast hole and the buffer hole have the same depth, the lower parts of the two are filled with emulsion explosives, and the upper parts of the two are filled with slag to form the upper filling section of the main blast hole and the upper filling section of the buffer hole, and the length of the upper filling section of the main blast hole is less than the length of the upper filling section of the buffer hole; the auxiliary hole has a depth less than the main blast hole, the lower part is filled with emulsion explosives, and the upper part is filled with slag to form the upper filling section of the auxiliary hole, and the length of the upper filling section of the auxiliary hole is less than the upper filling section of the main blast hole; the pre-cracking holes are arranged in order from bottom to top: A hole bottom reinforcement section filled with hole bottom explosives, a normal charging section filled with multiple middle emulsified cords, a hole mouth excess height section and a hole mouth filling section filled with hole slag, the hole bottom explosives and the middle emulsified cords are connected by a second detonating cord and led out of the hole mouth, the hole bottom explosives and the middle emulsified cords are arranged on the inner side of the pre-splitting hole in an uncoupled interval charging manner, the hole bottom reinforcement section and the normal charging section are 0.2 times the hole depth and 0.6 times the hole depth respectively, and the total length of the hole mouth excess height section and the hole mouth filling section is 0.2 times the hole depth.

[0009] According to another aspect of the present application, a blasting method for the blasting structure from the open pit to the boundary slope step described in the above technical solution is provided, the method comprising:

[0010] S1.1. First, drill holes and charge explosives in the pre-boundary blasting area according to the design drawings, and then blast. During blasting, the first blastholes in each row are detonated from the center to both sides, with a delay of 50ms between holes; if there are more than one row of the first blastholes, the first blasthole in the center of the front row is used as the central blasthole for detonation, with a delay of 50ms between holes and 80ms between rows, and then shovel loading is carried out in the pre-boundary blasting area in the conventional way;

[0011] S1.2. Drill holes and charge explosives in accordance with the design drawings in the blasting area of ​​the boundary slope, and then blast. The pre-splitting holes are detonated simultaneously with a delay of 0ms. The first main blasting holes are detonated with a delay of 100ms. The delay between holes is 40ms, and the delay between rows of blasting holes is 65ms.

[0012] According to another aspect of the present application, a post-blasting shoveling method for the blasting structure of the open pit to the boundary slope step described in the above technical solution is provided. After the blasting of the boundary slope blasting area, shoveling is performed according to the "intermittent stripping method". The specific method is as follows:

[0013] S2.1. Taking the buffer hole as the boundary and marking it, the blasting area of ​​the boundary slope is divided into two parts, front and rear, and stripped successively. The front side is the preliminary stripping part, and the rear side is the later stripping part including the step. Then, the preliminary stripping part on the front side of the buffer hole is shoveled in a conventional manner;

[0014] S2.2. The subsequent stripping part on the rear side of the buffer hole is excavated and loaded in layers. Taking the maximum excavation height h of the excavator as the standard, the later stripping part is divided into upper and lower parts and loaded laterally layer by layer. Combined with the slope angle, mark the front side of the pre-splitting hole at a distance of h / tan60°, and form areas ①, ② and ③ with the mark downward and on the slope. First, shovel area ① to leave space for the rock mass in area ② to lose balance and slide naturally. Then shovel area ② and finally shovel area ③.

[0015] Furthermore, during shoveling, the fluctuation of the working platform within 30 meters in length is limited to 2-3m, the boundary platform needs to have a smooth transition, and the height difference every 30 meters should not exceed 0.3-0.5m.

[0016] Compared with the prior art, the blasting structure, blasting method and post-blasting shoveling method from open pit to boundary slope of the present invention have the following beneficial effects:

[0017] (1) In terms of blasting, the present invention strictly divides the blasting area into a pre-boundary blasting area and a controlled blasting area of ​​the boundary slope according to the width of the platform from the final boundary, thereby realizing separate blasting and mining. At the same time, the rows of blastholes in the two areas are optimized, thereby greatly avoiding excessive blasting and excessive rock fragmentation caused by excessive blasting energy or excessive aftershock, and protecting the boundary slope surface from the blasting source.

[0018] (2) In the stripping operation, the present invention uses an intermittent stripping method to divide the blasting area into two parts with the buffer hole as the boundary, and stripping is performed successively. This method not only ensures the enhanced stripping of the main blasting hole source, but also prevents the final slope damage caused by over-excavation behind the buffer hole, thereby ensuring the formation of the final slope.

[0019] (3) In terms of parameter control of the standard step of the boundary slope, the present invention uses a step layering operation method and utilizes the characteristics of the material repose angle to ensure the parameter requirements of the step slope during construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of two blasting areas and the layout of each row of blast holes in the blasting structure from the open pit to the boundary slope of the present invention;

[0021] Figure 2 It is a schematic elevation diagram of the pre-boundary blasting area in the present invention;

[0022] Figure 3 It is a schematic elevation view of charging of the first blasthole in the present invention;

[0023] Figure 4 It is a schematic diagram of the time delay of detonation of the first blast hole in the pre-boundary blasting area in the present invention;

[0024] Figure 5 It is a schematic elevation diagram of the boundary slope blasting area in the present invention;

[0025] Figure 6 It is a schematic diagram of the pre-splitting charge in the present invention;

[0026] Figure 7 It is a schematic diagram of an intermittent stripping method in a blasting method for a blasting structure from an open pit to a boundary slope step in the present invention;

[0027] Figure 8 It is a schematic diagram of the subsequent stripping part of the rear side of the buffer hole in the present invention, and the layered excavation and shoveling;

[0028] In the figure: 1, pre-boundary blasting area; 11, first blast hole; 111, lower emulsion explosive section; 112, middle interval section; 113, middle emulsion explosive section; 114, upper blocking section; 115, lower emulsion explosive; 116, middle emulsion explosive; 117, hole slag; 118, detonator; 119, first detonating cord; 2, boundary slope blasting area; 21, main blast hole; 211, main blast hole The upper filling section of the hole; 221, the upper filling section of the buffer hole; 231, the upper filling section of the auxiliary hole; 22, the buffer hole; 23, the auxiliary hole; 24, the pre-crack hole; 241, the bottom reinforcement section of the hole; 242, the normal charging section; 243, the residual height section of the hole mouth; 244, the filling section of the hole mouth; 245, the explosive at the bottom of the hole; 246, the middle emulsified cord; 247, the second detonating cord; 25, the mark; 3, the safety platform. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the usual meanings understood by people with general skills in the field to which the present disclosure belongs. The "upper", "lower", "left", "right", "front", "back" and the like used in the patent application specification and claims of the present disclosure are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship also changes accordingly. The parts not described in detail in the present invention are all known technologies of technicians in the technical field.

[0030] Embodiment 1:

[0031] As the open pit steps advance to the final state, the step width gradually narrows as the blasting operation proceeds. Pre-splitting blasting is usually used to advance the steps to the final state to avoid over-blasting or under-blasting. Figure 1-6As shown, this embodiment provides a blasting structure for the open-pit mine to the boundary slope step. According to the width of the platform from the final boundary, the blasting areas are respectively set in sequence as the pre-boundary blasting area 1 and the boundary slope blasting area 2. By blasting the pre-boundary blasting area 1 first, conditions are created for the subsequent blasting of the boundary slope blasting area 2. The main goal of the pre-boundary blasting area 1 is to control the blasting range and reserve enough space for pre-cracking blasting.

[0032] Specifically, the front edge of the pre-boundary blasting area 1 and the rear edge of the boundary slope blasting area 2 are the free surface A and the upper step slope angle line B respectively, and the intersection of the two is the intersection line C; the width of the pre-boundary blasting area 1 is generally controlled at about 15m, and a number of rows of first blast holes 11 with an elevation angle of 90° are arranged in the area. Taking two rows of first blast holes 11 as an example, the distance between the free surface A and its adjacent first blast holes 11 is controlled at about 4m, the distance between the boundary line C and its adjacent first blast holes 11 is controlled at about 5m, the row spacing between two adjacent rows of first blast holes 11 is controlled at about 6m, and the hole spacing between two adjacent blast holes in each row of first blast holes 11 is controlled at 7-8m; the hole depth and hole diameter of the first blast hole 11 are designed according to the actual situation on site, generally the hole depth is 14m, the hole diameter is 250mm, and the first The blasthole 11 is composed of, from bottom to top, a lower emulsion explosive section 111 provided with a lower emulsion explosive 115, a middle interval section 112, a middle emulsion explosive section 113 provided with a middle emulsion explosive 116, and a hole slag 117 and an upper plugging section 114; the length of the lower emulsion explosive section 111 is greater than the middle emulsion explosive 116 and the middle interval section 112. Taking a hole depth of 14 m as an example, the lower emulsion explosive section 111 is charged with 6 m, the middle emulsion explosive 116 is charged with 1 m, the middle interval section 112 is 1 m, and the upper plugging section 114 is 6 m; the lower emulsion explosive section 111 and the middle emulsion explosive 116 are connected by a first detonating cord 119, and detonators 118 are respectively provided inside the two detonators 118, and the first detonating cords 119 are respectively connected to the two detonators 118.

[0033] The blasting area 2 to the boundary slope is usually controlled at about 23m, and four rows of blast holes are arranged in sequence in the area, namely: a main blasting hole 21 with an elevation angle of 90°, a buffer hole 22 and an auxiliary hole 23, and a pre-splitting hole 24 with an elevation angle of 60°. The distance between the main blasting hole 21 and the boundary line C is controlled at 4m to ensure that the rock can be thrown out normally during blasting. The rear side of the pre-splitting hole 24 is set as a safety platform 3, and the distance between the pre-splitting hole 24 and the upper step slope angle line B is not less than 6m, that is, the width of the safety platform 3 is not less than 6m, which is conducive to the erection and safety of subsequent facilities. The distance between two adjacent blast holes in each row of main blast holes 21, buffer holes 22 and auxiliary holes 23 is controlled at 5-6m, and the distance between two adjacent blast holes in each row of pre-splitting holes 24 is controlled at 1.5-2m, so as to form continuous and dense blast holes for detonation before the main blast holes 21, and form a through crack with a certain width between the blasting area and the reserved area, so as to reduce the damage to the reserved rock mass during blasting in the main blasting area, and form a flat contour surface, so as to achieve the effect of accurately controlling the blasting range; the row spacing between the buffer holes 22 and the main blast holes 21 and the auxiliary holes 23 is controlled at about 4.5m and about 2.8m respectively, and the row spacing between the auxiliary holes 23 and the pre-splitting holes 24 is controlled at about 5m.

[0034] The depth and diameter of the main blast hole 21, buffer hole 22, auxiliary hole 23 and pre-splitting hole 24 are designed according to the actual situation on site. In this embodiment, the main blast hole 21 and the buffer hole 22 have the same depth, generally about 13m, and the lower part of both are filled with emulsion explosives, and the upper part of both are filled with slag to form the upper filling section 211 of the main blast hole and the upper filling section 221 of the buffer hole, and the length of the upper filling section 211 of the main blast hole is less than the length of the upper filling section 221 of the buffer hole, and the length difference is controlled at about 1m; the auxiliary hole 23 is affected by the pre-splitting hole 24, and the depth is less than the depth of the main blast hole 21, and the lower part is filled with emulsion explosives, and the upper part is filled with slag to form the upper filling section 231 of the auxiliary hole, and the length of the upper filling section 231 of the auxiliary hole is less than the upper filling section 211 of the main blast hole.

[0035] The pre-splitting hole 24 is generally set at a diameter of about 140 mm and a hole depth of about 14 m. It is drilled by a submersible drilling rig and is arranged from bottom to top in sequence as a hole bottom reinforcement section 241 filled with hole bottom explosive 245, a normal charge section 242 filled with a plurality of middle emulsified cords 246, a hole mouth excess height section 243, and a hole mouth filling section 244 filled with hole slag. The hole bottom explosive 245 and the middle emulsified cord 246 are connected and led out of the hole mouth by a second detonating cord 247. The hole bottom explosive 245 and the middle emulsified cord 246 are arranged on the inner side of the pre-splitting hole 24 in an uncoupled interval charging manner. The lengths of the hole bottom reinforcement section 241 and the normal charge section 242 are 0.2 times and 0.6 times the hole depth, respectively. The sum of the lengths of the hole mouth excess height section 243 and the hole mouth filling section 244 is 0.2 times the hole depth.

[0036] Example 2

[0037] like Figure 1-7 A blasting method for the blasting structure from the open pit to the boundary slope step in Example 1 is provided, comprising:

[0038] S1.1, firstly, the pre-boundary blasting area 1 is drilled and charged according to the design drawings, and then blasting is performed. During blasting, the first blast holes 11 in each row are detonated from the center to both sides, and the delay between holes is 50ms; taking the first blast holes 11 in two rows as an example, the first blast hole 11 in the center of the front row is used as the central blast hole for detonation, the delay between holes is 50ms, and the delay between rows is 80ms, and then the pre-boundary blasting area 1 is shoveled in a conventional manner;

[0039] S1.2. Drill holes and load explosives in the boundary slope blasting area 2 according to the design drawings, and then blast. The pre-splitting holes 24 are detonated simultaneously with a delay of 0ms. The first main blasting hole 21 is detonated with a delay of 100ms, and the delay between holes is 40ms. Then, each row of blast holes is detonated with a delay of 65ms between rows, and the delay between holes is 40ms.

[0040] Example 3

[0041] like Figure 1-8 As shown, a post-blasting shoveling method for the blasting structure from the open pit to the boundary slope step in Example 2 is provided. After blasting in the boundary slope blasting area 2, in order to ensure the integrity of the half-hole wall during the shoveling process, the shoveling is performed according to the "intermittent stripping method". The specific method is as follows:

[0042] S2.1, with the buffer hole 22 as the boundary and marked, the boundary slope blasting area 2 is divided into two parts, the front and rear parts, and the stripping is carried out successively. The front part is the preliminary stripping part, and the rear part is the later stripping part including the step. Then, the preliminary stripping part on the front side of the buffer hole 22 is shoveled in a conventional manner;

[0043] S2.2. The subsequent stripping part on the rear side of the buffer hole 22 is excavated and shoveled in layers, and the parameters of the standard steps to the boundary slope are controlled at the same time. The step surface needs to be strictly controlled according to the standard of "even top and flat bottom", that is, the fluctuation of the working platform within 30 meters is limited to 2-3 meters; the boundary platform needs to have a smooth transition, and the height difference every 30 meters does not exceed 0.3-0.5 meters; the formation of umbrella eaves exceeding 1 meter is strictly prohibited; in specific operations, the maximum excavation height h of the excavator is used as the standard. For example, if the maximum excavation height h of the excavator is 7m, the later stripping part is divided into upper and lower parts and shoveled laterally layer by layer. Combined with the slope angle, mark 25 at the front side of the pre-splitting hole 24 at a distance of h / tan60°, that is, Mark 25 is set 4m before the pre-splitting hole, and the mark 25 forms area ①, area ② and area ③ downward with the slope surface. Since the repose angles of different materials are different, the size of the repose angle is related to the properties of the materials, such as particle size, shape, surface roughness, internal friction angle, water content, etc. The repose angle is also affected by environmental factors such as vibration, wind force, etc., but the size of the repose angle is generally less than 55°. Therefore, area ① is shoveled first to leave space for the rock mass in area ② that loses its balance and slides naturally, so that the upper rock mass slides to the bottom by its own weight, avoiding damage to the half-hole wall due to over-excavation, and then area ② is shoveled, and finally area ③ is shoveled.

[0044] During the blasting and shoveling process, various high-precision displacement monitoring points, vibration monitoring points, groundwater level monitoring points, etc. can be set up in the mining site, and various signs can be made to ensure construction safety.

Claims

1. The blasting structure from the open pit to the boundary slope step is characterized by: The invention comprises a pre-boundary blasting area (1) and a boundary slope blasting area (2) arranged in sequence, wherein the front edge of the pre-boundary blasting area (1) and the rear edge of the boundary slope blasting area (2) are a free surface (A) and a slope angle line (B) of the upper step respectively, and the intersection of the two is a boundary line (C); the pre-boundary blasting area (1) is provided with a plurality of rows of first blast holes (11) with an elevation angle of 90°, the free surface (A) is 4 m away from the adjacent first blast holes (11), and the boundary line (C) is 1 m away from the adjacent first blast holes (11). The distance between the adjacent first blast holes (11) is 5m; the boundary slope blasting area (2) is arranged with four rows of blast holes in sequence, namely: a main blast hole (21) with an elevation angle of 90°, a buffer hole (22) and an auxiliary hole (23) and a pre-splitting hole (24) with an elevation angle of 60°, the main blast hole (21) is 4m away from the boundary line (C), the rear side of the pre-splitting hole (24) is arranged as a safety platform (3), and the distance between the pre-splitting hole (24) and the upper step slope angle line (B) is not less than 6m.

2. The blasting structure from open pit to boundary slope step according to claim 1, characterized in that: If there are more than one row of the first blast holes (11), the row spacing between two adjacent rows of the first blast holes (11) is 6m, and the hole spacing between two adjacent blast holes in each row of the first blast holes (11) is 7-8m; the row spacing between two adjacent blast holes in each row of the main blast holes (21), buffer holes (22) and auxiliary holes (23) is 5-6m, and the row spacing between two adjacent blast holes in each row of the pre-splitting holes (24) is 1.5-2m; the row spacing between the buffer holes (22) and the main blast holes (21) and the auxiliary holes (23) is 4.5m and 2.8m respectively, and the row spacing between the auxiliary holes (23) and the pre-splitting holes (24) is 5m.

3. The blasting structure from open pit to boundary slope step according to claim 1 or 2, characterized in that: The first blasthole (11) comprises, from bottom to top, a lower emulsion explosive section (111) provided with a lower emulsion explosive (115), a middle spacing section (112), a middle emulsion explosive section (113) provided with a middle emulsion explosive (116), and a hole slag (117) and an upper blocking section (114); the length of the lower emulsion explosive section (111) is greater than that of the middle emulsion explosive (116) and the middle spacing section (112); the lower emulsion explosive section (111) and the middle emulsion explosive (116) are connected by a first detonating cord (119), and both are provided with detonators (118) respectively, and the two detonators (118) are respectively connected with the first detonating cord (119).

4. The blasting structure from open pit to boundary slope step according to claim 1 or 2, characterized in that: The main blast hole (21) and the buffer hole (22) have the same depth, and the lower parts of the two are filled with emulsion explosives, and the upper parts of the two are filled with slag to form the upper filling section (211) of the main blast hole and the upper filling section (221) of the buffer hole, respectively, and the length of the upper filling section (211) of the main blast hole is shorter than the length of the upper filling section (221) of the buffer hole; the auxiliary hole (23) has a depth less than the main blast hole (21), and the lower part thereof is filled with emulsion explosives, and the upper part thereof is filled with slag to form the upper filling section (231) of the auxiliary hole, and the length of the upper filling section (231) of the auxiliary hole is shorter than the upper filling section (211) of the main blast hole; the pre-cracking holes (24) are arranged from bottom to top in sequence as the bottom of the hole filled with bottom explosives (245) The invention relates to a reinforced section (241), a normal charge section (242) filled with a plurality of middle emulsified cords (246), a hole mouth excess height section (243) and a hole mouth plugging section (244) filled with hole slag. The bottom hole explosive (245) and the middle emulsified cord (246) are connected and led out of the hole mouth through a second detonating cord (247). The bottom hole explosive (245) and the middle emulsified cord (246) are arranged inside the pre-splitting hole (24) in an uncoupled interval charging manner. The bottom hole reinforced section (241) and the normal charge section (242) are 0.2 times the hole depth and 0.6 times the hole depth respectively. The total length of the hole mouth excess height section (243) and the hole mouth plugging section (244) is 0.2 times the hole depth.

5. The blasting method of the blasting structure from the open pit to the boundary slope step according to any one of claims 1 to 4, characterized in that: include: S1.

1. First, the pre-boundary blasting area (1) is drilled and charged according to the design drawings, and then blasting is performed. During blasting, the first blast holes (11) in each row are detonated from the center to both sides, with a delay of 50ms between holes; if there are more than one row of the first blast holes (11), the first blast hole (11) in the center of the front row is used as the central blast hole for detonation, with a delay of 50ms between holes and 80ms between rows, and then the pre-boundary blasting area (1) is shoveled in a conventional manner; S1.

2. Drilling and charging are performed in accordance with the design drawings at the boundary slope blasting area (2), and then blasting is performed. The pre-splitting holes (24) are detonated simultaneously with a delay of 0 ms, the first main blasting holes (21) are detonated with a delay of 100 ms, the delay between holes is 40 ms, and the delay between rows of blasting holes is 65 ms.

6. The method for shoveling after blasting of the blasting structure from the open pit to the boundary slope step as claimed in claim 5, characterized in that: After blasting at the boundary slope blasting area (2), shovel loading is performed according to the "intermittent stripping method", and the specific method is as follows: S2.1, taking the buffer hole (22) as the boundary and marking it, the boundary slope blasting area (2) is divided into two parts, the front and rear parts, and the stripping is carried out successively, the front part is the preliminary stripping part, and the rear part is the later stripping part including the step, and then the preliminary stripping part on the front side of the buffer hole (22) is shoveled in a conventional manner; S2.

2. The subsequent stripping part on the rear side of the buffer hole (22) is excavated and loaded in layers. The maximum excavation height h of the excavator is used as the standard. The subsequent stripping part is divided into upper and lower parts and loaded laterally layer by layer. In combination with the slope angle, a mark (25) is made at a distance of h / tan60° on the front side of the pre-splitting hole (24). The mark (25) is used to form areas ①, ② and ③ downward with the slope. Area ① is loaded first to leave space for the rock mass in area ② to lose balance and slide naturally. Then area ② is loaded, and finally area ③ is loaded.

7. The method for shoveling after blasting of the blasting structure from the open pit to the boundary slope step according to claim 6, characterized in that: During shoveling, the fluctuation of the working platform within 30 meters is limited to 2-3m, the boundary platform needs to have a smooth transition, and the height difference every 30 meters shall not exceed 0.3-0.5m.

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