Direction changing method for accurate mining outside-vein roadway

Abstract

The invention discloses a direction changing method for a mining preparation outside-vein roadway. Comprising the following steps that (1) a turning area is arranged on one side of an outside-vein roadway, a stoping access road is arranged on one side of the turning area, a drill jumbo is adopted for construction in the turning area, the hole depth and angle of each blast hole are formed in the turning area, two-time turning construction is adopted, the turning position and angle are determined through a total station, the blast holes are blasted, and the turning position and angle of each blast hole are determined; the outside-vein roadway turning operation is realized; (2) first-time direction-changing construction is conducted, 24 first blast holes and 20 first blast holes are constructed in total, and four first smooth surface holes are added; and (3) second-time turning construction is carried out on the basis of the first-time turning blasting, 24 second blasting holes are constructed in total, 20 second blasting holes are formed, and four second smooth surface holes are added. The method has the beneficial effects that the turning accuracy of the outside-vein roadway can be ensured, the problems of over-excavation and under-excavation are reduced, the tunnel face of the outside-vein roadway after blasting is smoother, the width of the outside-vein roadway is effectively controlled, and the smooth blasting half-hole rate is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of mine mining, and specifically to a method for changing the direction of an out-of-vein roadway for preparatory mining. Background Art

[0002] The construction of an out-of-vein roadway for preparatory mining is an essential engineering link in the process of mine mining, and its quality directly affects technical and economic indicators such as the ore recovery rate and dilution rate. The traditional method for changing the direction of an out-of-vein roadway during construction usually uses a rock drilling jumbo. In some complex geological environments, especially in the area where the out-of-vein roadway changes direction with the stoping drift, limited by the space and the size of the equipment, a series of problems are often faced, such as the hole angle and depth not meeting the construction requirements, the quality of the blast holes deteriorating, overbreak and underbreak of the roadway after blasting, poor smooth blasting effect, and difficult support.

[0003] The traditional method for changing the direction of an out-of-vein roadway during construction usually requires multiple blasting cycles to complete the direction change of the out-of-vein roadway. During this process, due to the limited construction space, construction workers need to adjust the depth and angle of the blast holes multiple times to meet the requirements of the direction change. Especially in a narrow space, the traditional construction method often results in an unsatisfactory direction change effect due to inaccurate blast hole parameters, causing problems such as space waste and uneven blasting. In addition, the traditional method for changing the direction of an out-of-vein roadway during construction usually requires three or more construction cycles. After each blasting, construction workers will readjust the depth and angle of the blast holes, resulting in a long construction period, serious material waste, high labor costs, and many errors and unstable factors during the construction process. This method not only prolongs the construction period but also increases the potential safety hazards during the operation and the amount of later repair work, resulting in low economic benefits.

[0004] In the traditional construction of changing the direction of an out-of-vein roadway, the size and turning radius of the rock drilling jumbo often limit the effective use of the operation space. Especially in a narrow out-of-vein roadway, it is difficult to accurately control the depth and angle of the blast holes. The traditional design of a single blasting angle and depth cannot adapt to these complex construction environments, so problems such as overbreak and underbreak are likely to occur, resulting in unstable quality and poor construction accuracy of the out-of-vein roadway, and ultimately affecting the stoping effect of the ore. Therefore, how to adopt an efficient and accurate construction method in a limited operation space to improve the construction accuracy of changing the direction of an out-of-vein roadway, reduce the errors and uncertainties in the traditional construction method, has become an urgent problem to be solved. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for changing the direction of an out-of-vein roadway for preparatory mining that is easy to operate, safe and reliable in operation, can ensure the accuracy of changing the direction of the out-of-vein roadway, reduce the problems of overbreak and underbreak, make the face of the out-of-vein roadway after blasting smoother, effectively control the width of the out-of-vein roadway, and significantly improve the semi-hole rate of smooth blasting.

[0006] A method for changing the direction of the access drift outside the ore vein of the present invention includes the following steps: 1) A direction-changing area is set on one side of the access drift outside the ore vein. A stoping drift is set on one side of the direction-changing area. Rock drilling jumbo is used for construction in the direction-changing area. By setting the hole depth and angle of each blast hole in the direction-changing area, two-time direction-changing construction is adopted. First, a total station is used to determine the position and angle of the direction change, and then blasting is carried out according to the set blast holes to realize the direction-changing operation of the access drift outside the ore vein; solve the problem of insufficient working space and improve the construction accuracy; 2) For the first-time direction-changing construction, a total of 24 first blast holes are constructed, including 20 first blast holes and 4 first smooth holes are added at the same time; 3) For the second-time direction-changing construction, it is carried out on the basis of the first-time direction-changing blasting. A total of 24 second blast holes are constructed, including 20 second blast holes and 4 second smooth holes are added at the same time.

[0007] In the step 2), the 20 first blast holes are evenly arranged along the direction-changing area of the access drift outside the ore vein and the stoping drift. Every 4 first blast holes are set as a group, and a total of five groups are set; for the first blast holes at the top, the connection lines between the first blast holes are arranged in an arc shape, and the connection lines between the first blast holes at the bottom are arranged in a horizontal line shape; 1 first smooth hole is arranged between each group of first blast holes, and a total of 4 first smooth holes.

[0008] The 4 first smooth holes are located between the first blast holes at the top.

[0009] For the first blast holes, every 4 first blast holes are set as a group, and the connection lines of the 4 first blast holes are arranged in a vertical line shape, and a total of five groups are set. The hole depth of the first group of first blast holes is 2.7 m, and the angle is 20°; the hole depth of the second group of first blast holes is 3.0 m, and the angle is 29°; the hole depth of the third group of first blast holes is 2.8 m, and the angle is 35°; the hole depth of the fourth group of first blast holes is 2.6 m, and the angle is 40°; the hole depth of the fifth group of first blast holes is 2.3 m, and the angle is 45°.

[0010] The parameters of the 4 first smooth holes are, from left to right in turn: the hole depth is 2.9 m, and the angle is 25°; the hole depth is 2.9 m, and the angle is 32°; the hole depth is 2.7 m, and the angle is 38°; the hole depth is 2.4 m, and the angle is 43°.

[0011] By optimizing the parameters of the first blast holes in the first direction-changing construction, and using the combined layout of the first blast holes and the first smooth blasting holes for blasting, in a limited operating space, a rock drilling jumbo can accurately change the direction in the off-vein roadway and the direction-changing area of the stoping drift; on the basis of the first direction-changing blasting, the second direction-changing construction is carried out. Through the arranged second blast holes and the first blast holes, while improving the blasting accuracy, a more comprehensive and thorough blasting can be achieved; the precise design ensures the accuracy of the off-vein roadway direction change, reduces the problems of overbreak and underbreak, and makes the face of the off-vein roadway after blasting smoother; the width of the off-vein roadway is effectively controlled, and the semi-hole rate of smooth blasting is significantly increased to 70%, reducing the roughness of the off-vein roadway surface, thus effectively improving the quality of the off-vein roadway.

[0012] Different from the traditional method that requires three blasting cycles, this method can complete the off-vein roadway direction change through two precise direction-changing constructions, significantly shortening the construction period. This innovation effectively reduces time waste and repetitive work, thereby improving the construction efficiency and reducing various costs during the construction period, including material and labor costs, with significant economic benefits. It can reduce the roof damage rate of the on-site off-vein roadway and reduce the risk of safe operation.

[0013] In the step 3) described above, 20 second blast holes are set, evenly arranged along the direction-changing area of the off-vein roadway and the stoping drift. Every 4 second blast holes are set as a group, and a total of five groups are set; for the second blast holes at the top, the connection lines between the second blast holes are arranged in an arc shape, and for the second blast holes at the bottom, the connection lines between the second blast holes are arranged in a horizontal line; 1 second smooth blasting hole is set between each group of second blast holes, and a total of 4 second smooth blasting holes are set.

[0014] The 4 second smooth blasting holes are located between the second blast holes at the top.

[0015] For the second blast holes described above, every 4 second blast holes are set as a group, and the connection lines of the 4 second blast holes are arranged in a vertical line, and a total of five groups are set. The hole depth of the first group of second blast holes is 1.5 m, and the angle is 30°; the hole depth of the second group of second blast holes is 1.9 m, and the angle is 42°; the hole depth of the third group of second blast holes is 1.7 m, and the angle is 51°; the hole depth of the fourth group of second blast holes is 1.7 m, and the angle is 55°; the hole depth of the fifth group of second blast holes is 2.3 m, and the angle is 60°.

[0016] The parameters of the 4 second smooth blasting holes are, from left to right in sequence: hole depth 1.7 m, angle 36°; hole depth 1.8 m, angle 47°; hole depth 1.7 m, angle 53°; hole depth 2.0 m, angle 57°.

[0017] Advantages of the present invention: 1) By optimizing the parameters of the first blast holes in the first directional change construction, this method uses the first blast holes and the first smooth blasting holes to jointly arrange for blasting. In a limited operation space, a rock drilling jumbo can accurately change direction in the directional change area of the off-vein roadway and the stoping drift. Based on the first directional change blasting, the second directional change construction is carried out. Through the arranged second blast holes and the first blast holes, while improving the blasting accuracy, it can also make the blasting more comprehensive and thorough. Precise design ensures the accuracy of the off-vein roadway directional change, reduces overbreak and underbreak problems, and makes the face of the off-vein roadway after blasting smoother. The width of the off-vein roadway is effectively controlled, and the semi-hole rate of smooth blasting is significantly increased to 70%, reducing the roughness of the off-vein roadway surface, thus effectively improving the quality of the off-vein roadway.

[0018] 2) Different from the traditional method that requires three blasting cycles, this method can complete the directional change of the off-vein roadway through two precise directional change constructions, significantly shortening the construction period. This innovation effectively reduces time waste and repetitive work, thereby improving the construction efficiency and reducing various costs during the construction period, including material and labor costs, with significant economic benefits. It can reduce the roof damage rate of the on-site off-vein roadway and the risk of safe operation. It saves 4800 kg of emulsion explosive used in the secondary blasting every year, and each kilogram of emulsion explosive is about 5.65 yuan, saving: 4800×5.65 = 27120 yuan; it saves 1500 digital electronic detonators used in the secondary blasting every year, and the unit price of each digital detonator is about 23 yuan, saving: 1500×23 = 34500 yuan; a total of 61600 yuan is saved.

[0019] 3) By increasing the smooth blasting holes and precisely designing the parameters of each blast hole, this method improves the quality of the off-vein roadway after blasting, especially the flatness of the face and the smooth blasting effect, which makes the subsequent support work smoother, reduces the parts that need to be repaired and adjusted, and ensures the long-term stability of the off-vein roadway.

[0020] 4) Due to the limitation of space in the traditional off-vein roadway directional change construction, this method can improve the blasting accuracy through precise blast hole design. By evenly arranging multiple first blast holes and second blast holes in the directional change area of the off-vein roadway and the stoping drift, and adding the first smooth blasting holes in the first blast holes and the second smooth blasting holes in the second blast holes, the blast hole layout is more comprehensive, overcoming the difficulty of narrow operation space and optimizing the space utilization efficiency. This improvement ensures that even in a limited space, construction can still be carried out efficiently, improving the operability of the working environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the layout structure of the off-vein roadway in the present invention; Figure 2Schematic layout of the first blast holes during the first directional change construction in the present invention; Figure 3 Schematic diagram of the parameters of the first blast holes during the first directional change construction in the present invention; Figure 4 Schematic layout of the second blast holes during the second directional change construction in the present invention; Figure 5 Schematic diagram of the parameters of the first and second blast holes during the second directional change construction in the present invention.

[0022] In the figure: cross - vein roadway 1, retreat stope access 2, directional change area 3, ore body 4, first blast hole 5, first blast hole 501, first smooth hole 502, second blast hole 6, second blast hole 601, second smooth hole 602. Detailed implementation method

[0023] The following will further explain the present invention with reference to the accompanying drawings.

[0024] Construction is carried out in the directional change area 3 between the cross - vein roadway 1 and the retreat stope access 2, where the working space is limited. The width of the cross - vein roadway 1 is 4.2 m and the height is 3.8 m. Therefore, precise blast hole design is required to adapt to the narrow working environment. The size of the rock drilling jumbo has a great limitation on the working space, and the turning radius also makes it difficult to achieve the ideal construction accuracy by traditional methods. To overcome this problem, the depth and angle of each blast hole are designed to optimize the use of the working space.

[0025] A method for changing the direction of a cross - vein roadway in the present invention includes the following steps: 1) A directional change area 3 is set on one side of the cross - vein roadway 1, and a retreat stope access 2 is set on one side of the directional change area 3. Construction is carried out in the directional change area 3 using a rock drilling jumbo. By setting the depth and angle of each blast hole in the directional change area 3, two - stage directional change construction is adopted. First, a total station is used to determine the position and angle of the directional change, and then blasting is carried out according to the set blast holes to achieve the directional change operation of the cross - vein roadway 1; optimize the parameters of each blast hole to solve the problem of insufficient working space and improve construction accuracy; optimize the parameters of each blast hole to solve the problem of insufficient working space and improve construction accuracy; 2) During the first directional change construction, a total of 24 first blast holes 5 are constructed, including 20 first blast holes 501, and 4 first smooth holes 502 are added at the same time; 3) During the second directional change construction, it is carried out on the basis of the first directional change blasting. A total of 24 second blast holes 6 are constructed, including 20 second blast holes 601, and 4 second smooth holes 602 are added at the same time.

[0026] In the said step 2), 20 first blast holes 501 are arranged evenly in the deflection area 3 of the cross - cut outside the vein 1 and the stoping drift 2. Every 4 first blast holes 501 form a group, and a total of five groups are set. For the first blast holes 501 at the top, the connection lines between the first blast holes 501 are arranged in an arc shape, and for the first blast holes 501 at the bottom, the connection lines between the first blast holes 501 are arranged in a horizontal line. One first smooth - wall hole 502 is arranged between each group of first blast holes 501, and a total of 4 first smooth - wall holes 502 are set.

[0027] The said 4 first smooth - wall holes 502 are located between the first blast holes 501 at the top.

[0028] For the said first blast holes 501, every 4 first blast holes 501 form a group. The connection lines of the 4 first blast holes 501 are arranged in a vertical line, and a total of five groups are set. The hole depth of the first group of first blast holes 501 is 2.7 m, and the angle is 20°; the hole depth of the second group of first blast holes 501 is 3.0 m, and the angle is 29°; the hole depth of the third group of first blast holes 501 is 2.8 m, and the angle is 35°; the hole depth of the fourth group of first blast holes 501 is 2.6 m, and the angle is 40°; the hole depth of the fifth group of first blast holes 501 is 2.3 m, and the angle is 45°.

[0029] The parameters of each group of first blast holes 501 are precisely designed according to the working space and equipment operability to ensure high - precision construction in a restricted space.

[0030] The parameters of the said 4 first smooth - wall holes 502 from left to right are as follows: hole depth 2.9 m, angle 25°; hole depth 2.9 m, angle 32°; hole depth 2.7 m, angle 38°; hole depth 2.4 m, angle 43°.

[0031] By optimizing the depth and angle of the first smooth - wall holes 502, the problems of over - excavation and under - excavation that may occur during the blasting process are reduced. It ensures that the face width of the cross - cut outside the vein 1 is between 5.5 - 6 m, and the smooth - wall blasting half - hole rate is increased to 70%.

[0032] Through the implementation of this scheme, the deflection area 3 of the cross - cut outside the vein 1 becomes more precise, the face width is effectively controlled, and the construction precision is greatly improved. Compared with the traditional scheme, the face width after blasting is significantly reduced, and the smooth - wall blasting half - hole rate is significantly increased, thus ensuring the quality of the cross - cut outside the vein 1 and the stability of the subsequent support.

[0033] In step 3), 20 second blast holes 601 are set. Along the variable direction area 3 of the cross - drift 1 outside the vein and the stope entry 2, every 4 second blast holes 601 form a group, and a total of five groups are set. For the second blast holes 601 at the top, the connection lines between the second blast holes 601 are arranged in an arc shape, and for the second blast holes 601 at the bottom, the connection lines between them are arranged in a horizontal line. One second smooth hole 602 is set between each group of second blast holes 601, and a total of 4 second smooth holes 602 are set.

[0034] The 4 second smooth holes 602 are located between the second blast holes 601 at the top.

[0035] For the second blast holes 601, every 4 second blast holes 601 form a group, and the connection lines of the 4 second blast holes 601 are arranged in a vertical line. A total of five groups are set. The hole depth of the first group of second blast holes 601 is 1.5 m and the angle is 30°; the hole depth of the second group of second blast holes 601 is 1.9 m and the angle is 42°; the hole depth of the third group of second blast holes 601 is 1.7 m and the angle is 51°; the hole depth of the fourth group of second blast holes 601 is 1.7 m and the angle is 55°; the hole depth of the fifth group of second blast holes 601 is 2.3 m and the angle is 60°.

[0036] The parameters of the 4 second smooth holes 602 are, from left to right in sequence: hole depth 1.7 m, angle 36°; hole depth 1.8 m, angle 47°; hole depth 1.7 m, angle 53°; hole depth 2.0 m, angle 57°.

[0037] After the first variable - direction blasting is completed, for further refined construction, a second variable - direction construction is carried out. By further optimizing the depth and angle of the second blast holes 601, the accuracy of the variable direction of the cross - drift 1 outside the vein is ensured.

[0038] By optimizing and setting the adjustment depth and angle of the second smooth holes 602, the blasting effect becomes more uniform, effectively improving the quality of the cross - drift 1 outside the vein after blasting.

[0039] After the second variable - direction blasting, the face width of the cross - drift 1 outside the vein is between 5.5 - 6 m, and the smooth - blasting half - hole rate is increased to 70%. This optimized design greatly reduces the errors and uncertainties in the traditional construction method, ensuring the accuracy and construction quality of the cross - drift 1 outside the vein.

[0040] The key advantage of this embodiment is that by precisely optimizing the depth and angle of each first blast hole 501 and second blast hole 601, the variable direction of the cross - drift 1 outside the vein for development only requires two cycles to meet the design requirements, while the traditional method requires at least three construction cycles. During this process, the construction personnel carry out construction in sequence according to the design plan to ensure that the depth and angle of each first blast hole 501 and second blast hole 601 meet the design requirements.

[0041] Through the two - time precise direction - changing construction method of the present invention, it is possible to significantly save blasting materials and digital detonators, reducing the cost of on - site operations. In addition, by optimizing the construction plan, the present invention reduces the damage to the roof of the off - vein roadway 1, reducing the operation safety risk.

[0042] This method can save the use of emulsion explosives and digital electronic detonators every year, directly saving about 61,600 yuan in costs. In terms of safety, it reduces the damage to the roof of the off - vein roadway 1, reducing potential safety hazards during operations and improving the safety of the construction process; by reducing the construction period, the construction efficiency has been significantly improved. The three - time blasting cycle of the traditional method consumes a large amount of time and cost in each cycle, while the two - time precise direction - changing construction method of the present invention reduces the construction period and cost, improving the economic benefits of the project; in the implementation case in April 2021, the optimized drivage off - vein roadway 1 direction - changing method of this method has obtained significant economic benefits: saving 4800 kg of emulsion explosives and 1500 detonators per year, saving a large amount of costs. At the same time, the improvement of construction accuracy also reduces the damage to the roof of the off - vein roadway 1, improving operation safety and the overall construction quality.

[0043] The so - called hole depth refers to the depth of the blast hole in blast hole blasting; the so - called angle refers to the angle between the direction of the blast hole and the horizontal plane in blasting operations. This angle has an important impact on the blasting effect because it determines the propagation direction and energy distribution of the explosive in the rock; the smooth - surface half - hole rate refers to the proportion of the remaining half - holes after blasting; smooth - surface blasting is a controlled blasting technology whose purpose is to form a smooth and flat wall surface on the excavation contour line; the smooth - surface blast holes are a row of blast holes drilled on the designed excavation contour line with a hole spacing matching the minimum resistance line, and uncoupled charging or other special charging structures are used. After the main body of the excavation is blasted, the charges in the smooth - surface blast holes are detonated simultaneously, thus forming a smooth and flat excavation surface that penetrates the smooth - surface blast holes.

[0044] The model of the rock - drilling jumbo is: SANDVIK DD2710; the length of the propulsion beam is: 5270 mm, the length of the drill pipe is: 3700 mm, the hole depth is: 3440 mm, the inner diameter of the R1 - turning radius is: 2900 mm, the outer diameter of the R2 - turning radius is: 5100 mm, and the total length of the vehicle body is: 10065 mm.

[0045] The model of the total station is: TS02 / 06 Powe.

[0046] The data table for the first direction - changing construction is shown in Table 1: As can be seen from Table 1, in the present invention, during the two time periods of January 15, 2025 and January 20, 2025, the hole depth of the second group is the largest, both being 3.01 m, and the hole depth of the fifth group is the smallest, both being 2.46 m.

[0047] The data sheet for the second direction change construction is shown in Table 2: As can be seen from Table 2, in the present invention, during the two time periods of January 16, 2025 and January 21, 2025, the hole depth of the fifth group is the largest, being 2.46 m and 2.45 m respectively, and the hole depth of the first group is the smallest, being 1.50 m and 1.51 m respectively.

Claims

1. A method for changing direction in a mining tunnel outside a predetermined vein, characterized in that: The method comprises the following steps: 1) A turning area (3) is provided on one side of the outer-vein tunnel (1), a mining access road (2) is provided on one side of the turning area (3), a drilling trolley is used for construction in the turning area (3), the depth and angle of each blasting hole are set in the turning area (3), and two turning constructions are adopted. First, the position and angle of the turning are determined by a total station, and then blasting is performed according to the set blasting holes, so as to realize the turning operation of the outer-vein tunnel (1); 2) The first diversion construction, a total of 24 first blasting holes (5) were constructed, of which 20 first blasting holes (501) were set, and 4 first polishing holes (502) were added at the same time; 3) The second reversal construction is carried out on the basis of the first reversal blasting, and a total of 24 second blasting holes (6) are constructed, of which 20 second blast holes (601) are set, and 4 second polishing holes (602) are added.

2. A method for changing direction in a mining tunnel outside a predetermined vein as claimed in claim 1, characterized in that: In the step 2), 20 first blast holes (501) are evenly arranged along the turning area (3) between the outer vein tunnel (1) and the mining access road (2), and each 4 first blast holes (501) form a group, and a total of five groups are arranged; the first blast holes (501) located at the top are arranged with the connecting lines between the first blast holes (501) arranged in an arc shape, and the connecting lines between the first blast holes (501) located at the bottom are arranged in a horizontal line; one first smooth hole (502) is arranged between each group of first blast holes (501), and a total of four first smooth holes (502) are arranged.

3. A method for changing direction in a mining tunnel outside a predetermined vein as claimed in claim 2, characterized in that: The four first polished holes (502) are located between the first blast holes (501) at the top.

4. A method for changing direction in a mining tunnel outside a predetermined vein as claimed in claim 3, characterized in that: The first blast holes (501) are grouped into four first blast holes (501), and the connecting line of the four first blast holes (501) is arranged in a vertical line, and there are five groups in total. The first group of first blast holes (501) has a hole depth of 2.7 m and an angle of 20°; the second group of first blast holes (501) has a hole depth of 3.0 m and an angle of 29°; the third group of first blast holes (501) has a hole depth of 2.8 m and an angle of 35°; the fourth group of first blast holes (501) has a hole depth of 2.6 m and an angle of 40°; the fifth group of first blast holes (501) has a hole depth of 2.3 m and an angle of 45°.

5. A method for changing direction in a tunnel outside a mining vein as claimed in claim 4, characterized in that: The parameters of the four first polishing holes (502) are as follows from left to right: hole depth 2.9m, angle 25°; hole depth 2.9m, angle 32°; hole depth 2.7m, angle 38°; hole depth 2.4m, angle 43°.

6. A method for changing direction in a mining tunnel outside a predetermined vein as claimed in claim 1, characterized in that: In the step 3), 20 second blast holes (601) are evenly arranged along the turning area (3) between the outer vein tunnel (1) and the mining access road (2), with 4 second blast holes (601) forming a group, and a total of five groups; the second blast holes (601) located at the top are connected in an arc shape, and the second blast holes (601) located at the bottom are connected in a horizontal line; one second smooth hole (602) is arranged between each group of second blast holes (601), and a total of four second smooth holes (602) are arranged.

7. A method for changing direction in a tunnel outside a mining vein as claimed in claim 6, characterized in that: The four second polished holes (602) are located between the second blast holes (601) at the top.

8. A method for changing direction in a tunnel outside a mining vein as claimed in claim 7, characterized in that: The second blast holes (601) are grouped with four second blast holes (601), and the connecting line of the four second blast holes (601) is arranged in a vertical line, which is arranged in five groups in total. The hole depth of the first group of second blast holes (601) is 1.5m, and the angle is 30°; the hole depth of the second group of second blast holes (601) is 1.9m, and the angle is 42°; the hole depth of the third group of second blast holes (601) is 1.7m, and the angle is 51°; the hole depth of the fourth group of second blast holes (601) is 1.7m, and the angle is 55°; the hole depth of the fifth group of second blast holes (601) is 2.3m, and the angle is 60°.

9. A method for changing direction in a tunnel outside a mining vein as claimed in claim 8, characterized in that: The parameters of the four second polishing holes (602) are as follows from left to right: hole depth 1.7m, angle 36°; hole depth 1.8m, angle 47°; hole depth 1.7m, angle 53°; hole depth 2.0m, angle 57°.

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