Blasting structure for bounded slope step of open stope
By setting blast holes in different areas on the slope of the open-pit mine and optimizing the blasting method and loading sequence, the problems of slope instability and uneven excavation interface were solved, and a safe and efficient blasting and loading process was achieved.
Patent Information
- Application Number
- CN202422957488.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-11-11
- Estimated Expiration
- 2034-11-29
AI Technical Summary
Open-pit mine slopes are prone to safety hazards and slope instability due to over-blasting or under-blasting during blasting, which affects mining efficiency and resource utilization. In addition, traditional deep-hole blasting has problems such as over-excavation and under-excavation, resulting in uneven excavation interfaces, which affects safety and production efficiency.
Employing sophisticated blasting techniques, pre-boundary blasting and boundary slope blasting zones were established in different areas. The layout of blast holes and delayed detonation methods were optimized, and intermittent stripping methods were used for shoveling to ensure that the slope stability and step parameters met the design specifications.
It effectively avoids the safety hazards caused by over-blasting or under-blasting, ensures slope stability and the flatness of the excavation interface, improves mining efficiency and resource utilization, and reduces mining costs.
Smart Images
Figure CN223538213U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of open-pit mine slope bench blasting technology, specifically involving the blasting structure, blasting method and post-blasting shovel loading method for the open-pit mine boundary slope. Background Technology
[0002] Open-pit slopes are one of the major hidden dangers to the safe production of open-pit mines. The stability of open-pit mine slopes is an important prerequisite for the normal production of the mine. The recovery and treatment of critical slopes in open-pit mines is an indispensable part of mining engineering technology. In open-pit mines, during long-term blasting and loading processes, the mine slopes are often in a state of incomplete boundary. In this state, excessive blasting energy or excessive aftershocks can lead to over-fragmentation of the rock, creating safety hazards and causing slope instability, impacting the safety of equipment and personnel. Under-blasting, on the other hand, makes loading difficult and hinders the design of standard slope steps. Furthermore, traditional deep-hole blasting often suffers from over-excavation and under-excavation, resulting in rough and uneven excavation interfaces, poor slope appearance, and even affecting the stability of the excavation interface, potentially triggering collapses and landslides. This is because the crushing and loosening effects of the blast holes intrude into the non-excavation area, causing localized damage to the rock on the other side of the excavation interface. Simultaneously, ensuring the integrity of the half-hole wall during the loading process after blasting is also a pressing issue that needs to be addressed in mining operations. Therefore, slopes that do not reach the boundary not only limit the effective mining area and reduce the amount of mineable minerals, but also affect mining efficiency and output, leading to increased mining costs. Furthermore, they can cause some mineral resources to be temporarily unable to be mined economically and effectively, affecting the overall resource utilization rate and economic benefits of the mine. Utility Model Content
[0003] This utility model provides a blasting structure, blasting method, and post-blast loading method for the boundary slope of an open-pit mine. It adopts refined blasting technology, from pre-boundary blasting to controlled blasting of the boundary slope, to create favorable conditions for the formation of the final boundary slope, while minimizing interference with the stability of the surrounding rock mass, ensuring that the slope morphology and stability strictly follow the design specifications, and avoiding safety hazards caused by over-blasting or under-blasting.
[0004] The technical solution to the technical problem is as follows:
[0005] According to one aspect of this application, a blasting structure for a boundary slope bench in an open-pit mine is provided, comprising a pre-boundary blasting area and a boundary slope blasting area arranged sequentially. The front edge of the pre-boundary blasting area and the rear edge of the boundary slope blasting area are respectively a free surface and the slope angle line of the upper bench, and the intersection of the two is a boundary line. The pre-boundary blasting area is provided with several rows of first blast holes with an elevation angle of 90°. The distance between the free surface and its adjacent first blast hole is 4m, and the distance between the boundary line and its adjacent first blast hole is 5m. The boundary slope blasting area is provided with four rows of blast holes arranged at intervals, namely: main blast holes, buffer holes, and auxiliary holes with an elevation angle of 90°, and pre-splitting holes with an elevation angle of 60°. The distance between the main blast holes and the boundary line is 4m. A safety platform is set behind the pre-splitting holes, and the distance between the pre-splitting holes and the slope angle line of the upper bench is not less than 6m.
[0006] Furthermore, if there is more than one row of the first blast holes, the row spacing between two adjacent rows of the first blast holes is 6m, and the spacing between two adjacent blast holes in each row is 7-8m; the spacing between two adjacent blast holes in each row of the main blast hole, buffer hole, and auxiliary hole is 5-6m, and the spacing between two adjacent blast holes in each row of the pre-splitting hole is 1.5-2m; the row spacing between the buffer hole and the main blast hole and the auxiliary hole is 4.5m and 2.8m, respectively, and the row spacing between the auxiliary hole and the pre-splitting hole is 5m.
[0007] Furthermore, the first borehole, from bottom to top, consists of a lower emulsion explosive section containing lower emulsion explosive, a middle interval section, a middle emulsion explosive section containing middle emulsion explosive, and a borehole slag and upper plugging section; the lower emulsion explosive section is longer than the middle emulsion explosive and the middle interval section; the lower emulsion explosive section and the middle emulsion explosive are connected by a first detonating cord, and each of them is equipped with an initiator, with a first detonating cord connected to each of the two initiators.
[0008] Furthermore, the main blast hole and the buffer hole have the same depth, and their lower parts are filled with emulsion explosive. Their upper parts are respectively filled with slag to form the upper filling section of the main blast hole and the upper filling section of the buffer hole, with the length of the upper filling section of the main blast hole being shorter than the length of the upper filling section of the buffer hole. The auxiliary hole has a depth less than the main blast hole depth, its lower part is filled with emulsion explosive, and its upper part is filled with slag to form the upper filling section of the auxiliary hole, with the length of the upper filling section of the auxiliary hole being shorter than the upper filling section of the main blast hole. The pre-splitting holes are arranged sequentially from bottom to top. The pre-splitting hole includes a bottom-reinforced section filled with bottom-hole explosive, a normal charge section filled with multiple central emulsion cartridges, a borehole opening height section, and a borehole opening plugging section filled with borehole slag. The bottom-hole explosive and the central emulsion cartridges are connected by a second detonating cord and led out of the borehole opening. The bottom-hole explosive and the central emulsion cartridges are arranged inside the pre-splitting hole in a non-coupled, spaced-out charging manner. The lengths of the bottom-reinforced section and the normal charge section are 0.2 times the hole depth and 0.6 times the hole depth, respectively. The sum of the lengths of the borehole opening height section and the borehole opening plugging section is 0.2 times the hole depth.
[0009] According to another aspect of this application, a blasting method is provided for the blasting structure of the open-pit mine to the boundary slope bench described in the above-mentioned technical solution, the method comprising:
[0010] S1.1 First, drill holes and load explosives in the pre-boundary blasting area according to the design drawings, and then carry out the blasting. During the blasting, the first blast hole in each row is detonated from the center to both sides, with a delay of 50ms between holes. If there are more than one row of first blast holes, the first blast hole 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. Then, the pre-boundary blasting area is shoveled in the conventional manner.
[0011] S1.2 Drill holes and load explosives in the blasting area of the boundary slope according to the design drawings, and then carry out blasting. The pre-splitting holes are detonated simultaneously with a delay of 0ms. The first main blasting hole is detonated with a delay of 100ms. The inter-hole delay is 40ms, and the inter-row delay of each row of blasting holes is 65ms.
[0012] According to another aspect of this application, a method for shoveling after blasting of the blasted structure of the open-pit mine to the boundary slope bench described in the above technical solution is provided. After blasting of the boundary slope blasting area, shoveling is carried out according to the "intermittent stripping method". The specific method is as follows:
[0013] S2.1. Using the buffer hole as the boundary and marking it, the blasting area of the boundary slope is divided into two parts, front and back, and then stripped in sequence. The front side is the initial stripping part, and the back side is the later stripping part including the step. Then, the initial stripping part in front of the buffer hole is shoveled in the conventional way.
[0014] S2.2. The subsequent stripping section behind the buffer hole is excavated and shoveled in layers. Taking the maximum excavation height h of the excavator as the standard, the later stripping section is divided into upper and lower parts and shoveled laterally layer by layer. Combined with the slope angle, a mark is made at a distance of h / tan60° in front of the pre-splitting hole. With this mark, areas ①, ② and ③ are formed downward with the slope. Area ① is shoveled first to leave space for the rock mass in area ② to slide down naturally due to loss of balance. Then area ② is shoveled, and finally area ③ is shoveled.
[0015] Furthermore, during loading, the fluctuation of the working platform within 30 meters should be limited to 2-3 meters, the boundary platform should transition smoothly, and the height difference should not exceed 0.3-0.5 meters every 30 meters.
[0016] Compared with the prior art, the blasting structure, blasting method, and post-blast loading method for the open-pit mine to boundary slope described in this utility model have the following beneficial effects:
[0017] (1) In terms of blasting, this utility model strictly divides the blasting area into a pre-boundary blasting area and a controlled blasting area on the boundary slope according to the width of the platform from the final boundary, so as to realize separate blasting and separate mining. At the same time, the layout of each row of blast holes in the two areas is optimized, which greatly avoids the excessive rock fragmentation caused by excessive blasting energy or excessive aftershock, and protects the boundary slope from the blasting source.
[0018] (2) In terms of stripping operation, this utility model uses an intermittent stripping method, with the buffer hole as the boundary, to divide the blasting area into two parts for stripping in sequence. This method not only ensures the enhanced stripping of the main blasting hole material, but also prevents the final slope damage caused by over-excavation behind the buffer hole, thus ensuring the formation of the final slope.
[0019] (3) Regarding the parameter control of the standard steps of the boundary slope of this utility model, the parameter requirements of the step slope are guaranteed during construction by using the step layer operation method and utilizing the characteristics of the material's angle of repose. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the two blasting zones and the layout of each row of blast holes in the blasting structure from the open-pit mine to the boundary slope of this utility model.
[0021] Figure 2 This is a schematic elevation view of the pre-boundary blasting area in this utility model;
[0022] Figure 3 This is a schematic elevation view of the first borehole loading of explosives in this utility model;
[0023] Figure 4 This is a schematic diagram of the detonation delay of the first blast hole in the pre-boundary blasting area in this utility model;
[0024] Figure 5 This is a schematic elevation view of the blasting area on the boundary slope in this utility model;
[0025] Figure 6 This is a schematic diagram of the pre-splitting hole charging method in this utility model;
[0026] Figure 7 This is a schematic diagram of the intermittent stripping method in the blasting method of the blasting structure of the open-pit mine to the boundary slope bench in this utility model;
[0027] Figure 8 This is a schematic diagram of the layered excavation shovel installation for the subsequent stripping section behind the buffer hole in this utility model.
[0028] In the diagram: 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 plugging section; 115. Lower emulsion explosive; 116. Middle emulsion explosive; 117. Hole debris; 118. Detonator; 119. First detonating cord; 2. Boundary slope blasting area; 21. Main blast hole; 211. Main blast hole. 221. Upper filling section of the borehole; 231. Upper filling section of the buffer borehole; 22. Buffer borehole; 23. Auxiliary borehole; 24. Pre-splitting borehole; 241. Bottom reinforcement section of the borehole; 242. Normal charging section; 243. Bottom clearance section of the borehole; 244. Bottom filling section of the borehole; 245. Bottom explosive; 246. Middle emulsion charge; 247. Second detonating cord; 25. Marking; 3. Safety platform. Detailed Implementation
[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this disclosure pertains. The terms "upper," "lower," "left," "right," "front," and "rear" used in the present patent application specification and claims are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship also changes accordingly. Any aspects not detailed in the present utility model are well-known technologies to those skilled in the art.
[0030] Example 1:
[0031] As the open-pit bench advances towards its final boundary, the bench width gradually narrows with blasting operations. Pre-splitting blasting is typically used to advance the bench to its final boundary. To avoid over-blasting or under-blasting, such as... Figure 1-6 As shown, this embodiment provides a blasting structure for the slope bench of an open-pit mine. Based on the width of the platform from the final boundary, the blasting areas are sequentially set as a pre-boundary blasting area 1 and a boundary slope blasting area 2. By first blasting the pre-boundary blasting area 1, conditions are created for the subsequent blasting of the boundary slope blasting area 2. The main objective of the pre-boundary blasting area 1 is to control the blasting range and reserve sufficient space for pre-splitting blasting.
[0032] Specifically, the front edge of the pre-boundary blasting zone 1 and the rear edge of the boundary slope blasting zone 2 are the free face A and the slope angle line of the upper step B, respectively, with the boundary line C being the intersection of the two. The width of the pre-boundary blasting zone 1 is generally controlled at around 15m. Several rows of first blast holes 11 with an elevation angle of 90° are set within this zone. Taking two rows of first blast holes 11 as an example, the distance between the free face A and its adjacent first blast hole 11 is controlled at around 4m, the distance between the boundary line C and its adjacent first blast hole 11 is controlled at around 5m, the spacing between adjacent rows of first blast holes 11 is controlled at around 6m, and the spacing between two adjacent blast holes in each row of first blast holes 11 is controlled at 7-8m. The depth and diameter of the first blast hole 11 are designed according to the actual site conditions, generally with a depth of 14m and a diameter of 250mm. The borehole 11 consists of, from bottom to top, a lower emulsion explosive section 111 containing a lower emulsion explosive 115, a middle interval section 112, a middle emulsion explosive section 113 containing a middle emulsion explosive 116, and a borehole cinder section 117 and an upper plugging section 114. The lower emulsion explosive section 111 is longer than the middle emulsion explosive 116 and the middle interval section 112. Taking a borehole depth of 14m as an example, the lower emulsion explosive section 111 has a charge of 6m, the middle emulsion explosive 116 has a charge of 1m, the middle interval section 112 has a charge of 1m, and the upper plugging section 114 has a charge of 6m. The lower emulsion explosive section 111 and the middle emulsion explosive 116 are connected by a first detonating cord 119. Both sections are equipped with detonators 118, and the first detonating cord 119 is connected to each of the two detonators 118.
[0033] The blasting area 2 at the boundary slope is usually controlled at around 23m. Within this area, four rows of blast holes are arranged at intervals: a main blast hole 21 with an elevation angle of 90°, a buffer hole 22, an auxiliary hole 23, and a pre-splitting hole 24 with an elevation angle of 60°. The distance between the main blast hole 21 and the boundary line C is controlled at 4m to ensure that the rock can be ejected normally during blasting. A safety platform 3 is set behind the pre-splitting hole 24, and the distance between the pre-splitting hole 24 and the slope angle line B of the upper step 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 of subsequent facilities and safety. The spacing between adjacent boreholes in each row of main blast holes 21, buffer holes 22, and auxiliary holes 23 is controlled at 5-6m, and the spacing between adjacent boreholes in each row of pre-splitting holes 24 is controlled at 1.5-2m, forming a continuous and dense network of boreholes. These boreholes are used to detonate before the main blast holes 21, creating a through crack of a certain width between the blasting zone and the reserved zone. This reduces the damage to the reserved rock mass during the blasting of the main blasting zone and forms a smooth contour surface, thereby achieving precise control of the blasting range. The spacing between buffer holes 22 and main blast holes 21 and auxiliary holes 23 is controlled at approximately 4.5m and 2.8m, respectively, and the spacing between auxiliary holes 23 and pre-splitting holes 24 is controlled at approximately 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 site conditions. In this embodiment, the main blast hole 21 and buffer hole 22 have the same depth, generally around 13m. The lower part of both is filled with emulsion explosive, and the upper part of both is filled with hole slag to form the upper filling section 211 of the main blast hole and the upper filling section 221 of the buffer hole, respectively. 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 to be around 1m. The auxiliary hole 23 is affected by the pre-splitting hole 24 and has a depth less than that of the main blast hole 21. The lower part of the auxiliary hole is filled with emulsion explosive, and the upper part of the auxiliary hole is filled with hole slag to form the upper filling section 231 of the auxiliary hole. The length of the upper filling section 231 of the auxiliary hole is less than that of the upper filling section 211 of the main blast hole.
[0035] The pre-splitting hole 24 is generally set with a diameter of about 140 mm and a depth of about 14 m. It is drilled by a submersible drill. From bottom to top, it is set as follows: bottom reinforcement section 241 filled with bottom explosive 245, normal charge section 242 filled with multiple central emulsion cartridges 246, borehole height section 243, and borehole filling section 244 filled with borehole slag. The bottom explosive 245 and the central emulsion cartridges 246 are connected by a second detonating cord 247 and led out of the borehole. The bottom explosive 245 and the central emulsion cartridges 246 are set inside the pre-splitting hole 24 using a non-coupled interval charging method. The lengths of the bottom reinforcement section 241 and the normal charge section 242 are 0.2 times the borehole depth and 0.6 times the borehole depth, respectively. The sum of the lengths of the borehole height section 243 and the borehole filling section 244 is 0.2 times the borehole depth.
[0036] Example 2
[0037] like Figure 1-7 The present invention provides a blasting method for a blasting structure from an open-pit mine to a boundary slope bench, as described in Embodiment 1, comprising:
[0038] S1.1 First, boreholes and explosives are drilled and loaded into the pre-boundary blasting area 1 according to the design drawings, and then blasting is carried out. During blasting, the first borehole 11 of each row adopts the center-to-side detonation method, with a 50ms delay between boreholes; taking two rows of first boreholes 11 as an example, the first borehole 11 in the center of the front row is used as the center borehole for detonation, with a 50ms delay between boreholes and an 80ms delay between rows. Then, the pre-boundary blasting area 1 is shoveled in the conventional manner.
[0039] S1.2. Drill holes and load explosives in the blasting area 2 of the boundary slope according to the design drawings, and then carry out blasting. 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 a delay of 40ms between holes. Then, each row of blasting holes is detonated with a delay of 65ms between rows and a delay of 40ms between holes.
[0040] Example 3
[0041] like Figure 1-8 As shown, a method for shoveling after blasting of the blasted structure from the open-pit mine to the boundary slope bench in Embodiment 2 is provided. After blasting in blasting area 2 of the boundary slope, in order to ensure the integrity of the half-hole wall during shoveling, the shoveling is carried out according to the "intermittent stripping method". The specific method is as follows:
[0042] S2.1. Using the buffer hole 22 as the boundary and marking it, divide the blasting area 2 of the boundary slope into two parts and peel them off one after the other. The front side is the initial peeling part, and the rear side is the later peeling part including the step. Then, the initial peeling part in front of the buffer hole 22 is shoveled in the conventional way.
[0043] S2.2. The subsequent stripping section behind buffer hole 22 is excavated and shoveled in layers. Simultaneously, the parameters of the standard steps on the boundary slope are controlled. The step surface must be strictly controlled according to the standard of "even sides and flat bottom," meaning the fluctuation within the 30-meter length of the working platform is limited to 2-3 meters; the boundary platform must transition smoothly, with a height difference of no more than 0.3-0.5 meters every 30 meters; the formation of overhangs 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 is 7m, the subsequent stripping section is divided into upper and lower parts and shoveled laterally layer by layer. Based on the slope angle, a mark 25 is made on the front side of the pre-splitting hole 24 at a distance of h / tan60°. Marker 25 is set 4m in front of the pre-splitting hole. With marker 25 downwards, it forms areas ①, ② and ③ with the slope. Since the angle of repose of different materials is different, the size of the angle of repose is related to the properties of the material, such as particle size, shape, surface roughness, internal friction angle, moisture content, etc. The angle of repose is also affected by environmental factors such as vibration and wind. However, the size of the angle of repose is generally less than 55°. Therefore, area ① is shoveled first to leave space for the rock mass in area ② to slide down naturally due to the loss of balance. This allows the upper rock mass to slide down to the bottom by its own weight, avoiding damage to the half-hole wall due to over-excavation. Then area ② is shoveled, and finally area ③ is shoveled.
[0044] During blasting and loading operations, various high-precision displacement monitoring points, vibration monitoring points, and groundwater level monitoring points can be set up in the mining area, and various markings should be made to ensure construction safety.
Claims
1. A blasting structure for the slope bench from an open-pit mine to the boundary, characterized in that, The system includes a pre-boundary blasting zone (1) and a boundary slope blasting zone (2) arranged sequentially. The front edge of the pre-boundary blasting zone (1) and the rear edge of the boundary slope blasting zone (2) are the free surface (A) and the slope angle line of the upper step (B), respectively, and the intersection of the two is the boundary line (C). The pre-boundary blasting zone (1) is provided with several rows of first blast holes (11) with an elevation angle of 90°. The distance between the free surface (A) and its adjacent first blast hole (11) is 4m. The boundary line (C) and the... The distance between the adjacent first blast hole (11) is 5m; the boundary slope blasting area (2) is provided with four rows of blast holes at intervals, namely: main blast hole (21) with an elevation angle of 90°, buffer hole (22) and auxiliary hole (23) and pre-splitting hole (24) with an elevation angle of 60°. The distance between the main blast hole (21) and the boundary line (C) is 4m. 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 slope angle line (B) of the upper step is not less than 6m.
2. The blasting structure for the open-pit mine to boundary slope bench as described in claim 1, characterized in that, If there is more than one row of the first blast hole (11), the row spacing between two adjacent rows of the first blast hole (11) is 6m, and the hole spacing between two adjacent blast holes in each row of the first blast hole (11) is 7-8m; the spacing between two adjacent blast holes in each row of the main blast hole (21), buffer hole (22) and auxiliary hole (23) is 5-6m, and the spacing between two adjacent blast holes in each row of the pre-splitting hole (24) is 1.5-2m; the row spacing between the buffer hole (22) and the main blast hole (21) and the auxiliary hole (23) is 4.5m and 2.8m respectively, and the row spacing between the auxiliary hole (23) and the pre-splitting hole (24) is 5m.
3. The blasting structure for the open-pit mine to boundary slope bench according to claim 1 or 2, characterized in that, The first borehole (11) consists of, from bottom to top, a lower emulsion explosive section (111) containing a lower emulsion explosive (115), a middle interval section (112), a middle emulsion explosive section (113) containing a middle emulsion explosive (116), and a borehole slag (117) and an upper plugging section (114); the lower emulsion explosive section (111) is longer than the middle emulsion explosive (116) and the middle interval section (112); the lower emulsion explosive section (111) and the middle emulsion explosive (116) are connected by a first detonating cord (119), and each of them is provided with a detonator (118), and the two detonators (118) are respectively connected with the first detonating cord (119).
4. The blasting structure for the open-pit mine to boundary slope bench according to claim 1 or 2, characterized in that, The main blast hole (21) and the buffer hole (22) have the same depth. The lower part of both is filled with emulsion explosive, and the upper part of both is filled with hole slag to form the upper filling section (211) of the main blast hole and the upper filling section (221) of the buffer hole, respectively. 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. The auxiliary hole (23) has a depth less than the depth of the main blast hole (21). The lower part of the auxiliary hole is filled with emulsion explosive, and the upper part of the auxiliary hole is filled with hole slag to form the upper filling section (231). The length of the upper filling section (231) of the auxiliary hole is less than the length of the upper filling section (211) of the main blast hole. The pre-splitting hole (24) is set from bottom to top as the bottom of the hole filled with hole bottom explosive (245). The pre-splitting hole (24) consists of a reinforced section (241), a normal charge section (242) filled with multiple central emulsion cartridges (246), a borehole height section (243), and a borehole filling section (244) filled with borehole slag. The bottom explosive (245) and the central emulsion cartridges (246) are connected by a second detonating cord (247) and led out of the borehole. The bottom explosive (245) and the central emulsion cartridges (246) are arranged inside the pre-splitting hole (24) in a non-coupled interval charge manner. The lengths of the bottom 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 sum of the lengths of the borehole height section (243) and the borehole filling section (244) is 0.2 times the hole depth.