Presplitting blasting structure and method for counter-inclined broken side slope

Abstract

The invention discloses a presplitting blasting structure and method for an anti-tilting broken slope. The presplitting blasting structure comprises a presplitting hole and an empty hole. The pre-splitting holes are arranged in a row on the designed boundary side slope line, and the empty holes are arranged between the adjacent pre-splitting holes; the presplitting holes are filled with explosives, and the empty holes are not filled with the explosives. According to the method, the unevenness of the pre-splitting surface is avoided, it is guaranteed that a smooth wall surface is formed more easily after pre-splitting blasting, the problem that the slope is unstable due to the fact that blasting vibration damage is large, slope treatment is difficult, and the rock breaking lumpiness is large is solved, the production task can be completed more safely and efficiently, and the production efficiency is improved. The technical process is simple, the implementation is convenient, the cost is low, the presplitting effect is good, the slope treatment investment is low, a large amount of capital investment can be saved, and the ore supply problem that the lower ore body cannot be exposed due to limit suppression for a long time is solved; the problem that the reserved slope surface is prone to being damaged by traditional presplitting blasting is solved to the maximum extent, and the method is particularly suitable for slope presplitting blasting of counter-tilting strata in surface mining.

Description

Technical Field

[0001] The present invention relates to mine blasting technology, in particular to a pre-splitting blasting structure and method for an anti-dipping fractured slope. Background Art

[0002] China is rich in mineral resources. Most of the mine exploitations still adopt open-pit mining, and the blasting effect will directly affect the economic cost input of the whole exploitation process. Therefore, if we want to better reduce the mine exploitation cost and maximize the mine exploitation benefit, we need to continuously explore and excavate in the aspect of blasting methods. How to ensure the blasting effect and improve the blasting quality without increasing the blasting cost input has gradually become the pursued goal.

[0003] Under the existing technical conditions, when pre-splitting blasting is carried out on an anti-dipping fractured slope, the blasting effect is not good, and it is not easy to appear a smooth wall surface, resulting in the pre-splitting surface being uneven. Under the influence of rain, sun exposure and blasting vibration, there are multiple landslides and potential landslide signs, posing a threat to the operating personnel and equipment in the lower part of the stope. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a pre-splitting blasting structure for an anti-dipping fractured slope that can effectively improve the utilization rate of explosive energy; the present invention also provides a pre-splitting blasting method for an anti-dipping fractured slope.

[0005] To solve the above technical problem, the technical solution adopted by the structure of the present invention is: it includes pre-splitting holes and empty holes; a row of pre-splitting holes is arranged on the designed boundary slope line, and the empty holes are arranged between adjacent pre-splitting holes; explosives are loaded in the pre-splitting holes, and no explosives are loaded in the empty holes.

[0006] Further, the empty holes are arranged at the middle positions between adjacent pre-splitting holes.

[0007] Further, the aperture of the empty holes is 4 / 3 to 5 / 3 times that of the pre-splitting holes. Further, the hole spacing of the pre-splitting holes is 16 to 24 times their aperture.

[0008] Further, the charging section of the pre-splitting holes from top to bottom is a weakening section, a normal section and a strengthening section in sequence; the explosives include weakening section emulsion explosives, normal section emulsion explosives, strengthening section emulsion explosives, detonating cords, upper digital electronic detonators and lower digital electronic detonators; the upper part of the detonating cord is positively connected to the upper digital electronic detonator, and the lower part is positively connected to the lower digital electronic detonator.

[0009] Furthermore, the charging length of the normal section of the pre-splitting hole is 80% - 85% of the total charging length of the pre-splitting hole, and the charging lengths of the enhanced section and the weakened section of the pre-splitting hole are respectively 7.5% - 10% of the total charging length of the pre-splitting hole; the charge amount per unit length of the enhanced section is 2 - 5 times that of the normal section of the pre-splitting hole per unit length, and the charge amount per unit length of the weakened section is 0.45 - 0.55 times that of the normal section of the pre-splitting hole per unit length.

[0010] Further, both the pre-splitting hole and the relief hole are provided with spacers at a position 2 - 3 m below the hole mouth, and the upper part of the spacer is tamped to form a tamping section; the lengths of the tamping sections of the pre-splitting hole and the relief hole are not less than 1.5 times the hole diameter of the pre-splitting hole.

[0011] Further, two rows of buffer holes are arranged between the main blast holes and the pre-splitting holes.

[0012] To solve the above technical problems, the method of the present invention adopts the above blasting structure, and the technical solution adopted is: the pre-splitting holes are simultaneously detonated with 0 ms delay.

[0013] Further, the main blast holes are detonated hole by hole along the isochronous line, and the buffer holes are detonated hole by hole along the isochronous line; the first detonating hole in the first row of the main blast holes is set to detonate with a 100 ms delay.

[0014] Further, the upper digital electronic detonator and the lower digital electronic detonator of the pre-splitting hole are instantaneously detonated, and are conducted through detonating cords to detonate the latex explosives in the weakened section, the normal section, and the enhanced section simultaneously.

[0015] The beneficial effects produced by adopting the above technical solutions are as follows: by arranging a large-diameter relief hole between two adjacent pre-splitting blast holes, the explosion energy of the pre-splitting hole is not discharged through the hole mouth of the pre-splitting hole, but is released through the position of the relief hole, improving the utilization rate of explosive energy, reducing the damage of the explosion energy of the pre-splitting hole to the reserved rock mass. At the same time, since no charge is placed at the position of the relief hole, the damage degree of the reserved rock mass after blasting is the smallest, so that the pre-splitting surface formed by the penetration of the pre-splitting hole and the relief hole is smoother and flatter, and the slope stability is better. The present invention plays a role in protecting the stability of the slope, can reduce the impact damage of blasting on the reserved slope surface, reduce the safety threat of floating stones on the slope to the lower operating personnel and equipment, and at the same time reduce the economic investment in slope reinforcement and slope monitoring.

[0016] The present invention makes effective use of the explosive in the presplitting hole by changing the charging structure of the presplitting hole; the precise delay of digital electronic detonators is adopted, the upper end of the detonating cord is tied to weaken the explosive and the detonator; the lower end is tied to strengthen the explosive and the detonator, and the detonating cord, explosive, detonator and leg wire are fixed by bamboo slices, and then connected to the initiation network. The upper and lower explosives are simultaneously detonated by the digital electronic detonator, so that the explosive in the presplitting hole can be more accurately instantaneously detonated, and the explosion energy of the instantaneous explosive is increased; at the same time, the explosion shock wave energy does not discharge through the orifice of the presplitting hole, but overflows through the adjacent large-diameter empty hole, and the empty hole is not filled with explosive, reducing the damage degree of the explosive explosion to the reserved slope.

[0017] The present invention avoids the unevenness of the presplitting surface, ensures that a smooth wall surface is more easily formed after presplitting blasting, solves many problems such as large blasting vibration hazards, difficult slope treatment, and large rock fragmentation, which cause slope instability, and can complete the production task more safely and efficiently. The technical process is simple, easy to implement, low in cost, good in presplitting effect, low in slope treatment investment. It can not only save a large amount of capital investment, but also solve the problem of ore supply that the lower ore body cannot be exposed due to long-term boundary suppression; it maximally solves the problem that the traditional presplitting blasting is easy to damage the reserved slope surface, and is especially suitable for the presplitting blasting of the slope of reverse-dipping rock strata in open-pit mines, such as Sijiaying Stope. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0019] Figure 1 is a schematic structural diagram of the presplitting blasting structure described in the present invention; Figure 2 is a schematic structural diagram of the blast hole described in the present invention.

[0020] In the figure: bamboo slice 1, detonator slot 2, presplitting hole stuffing section 3, leg wire of detonator 4, upper digital electronic detonator 5, weakened section latex explosive 6, normal section latex explosive 7, detonating cord 8, strengthened section latex explosive 9, lower digital electronic detonator 10, empty hole stuffing section 11, empty hole section 12, main blast hole Z, buffer hole H, presplitting hole Y, empty hole K. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] In the conventional technology, when blasting the reverse-dipping broken slope, the conventional blast hole structure includes a main blast hole Z, a buffer hole H and a presplitting hole Y; a row of presplitting holes are arranged on the designed boundary slope line, and the buffer hole H is arranged between the main blast hole Z and the presplitting hole Y. Figure 1 、 Figure 2 As shown in, the presplitting blasting structure of this reverse-dipping broken slope is improved on the conventional blast hole structure, and the structure is as follows: 1) An empty hole K without charge is set between the pre-splitting holes to guide the release of the explosion shock wave of the pre-splitting hole Y; the empty hole K is arranged between adjacent pre-splitting holes Y, preferably in the middle between adjacent pre-splitting holes Y; the pre-splitting holes Y are arranged in a row on the designed boundary slope line, and the blast hole depth of the pre-splitting holes Y is L Y =H / sinα, aperture D Y =150~165mm, hole spacing J Y =(16~24)D Y , where α is the drilling angle, unit: °. The blast hole depth of the empty hole K is the same as the blast hole depth of the pre-splitting hole Y, that is, the blast hole depth of the empty hole K is L K = L Y =H / sinα, the aperture D of the pore K K The diameter D of the pre-split hole Y Y 4 / 3~5 / 3, i.e. D K =4 / 3D Y ~5 / 3D Y The empty hole K is located in the middle between the adjacent pre-crack holes Y. Therefore, the hole spacing J between the pre-crack holes Y and the empty hole K is (8-12)D. Y , where α is the drilling angle, unit: °. For example, the diameter of the pre-splitting hole Y is D Y =150mm, then the hole spacing J of the pre-crack hole Y Y The value range is 2.4~3.6m; the aperture D of the empty hole K K The value range is 200mm~250mm, and the hole spacing J between the pre-crack hole Y and the empty hole K ranges from 1.2 to 1.8m.

[0022] 2) Two rows of buffer holes H are set between the main gun hole Z and the pre-splitting hole Y. The lower part of the buffer hole H is inclined toward the direction close to the main gun row. The inclination angle is the following perforation angle; among them, the buffer holes in a row close to the pre-splitting hole Y have a hole depth of 5 to 7 m and a perforation angle of 64° to 75°; the buffer holes in a row close to the main gun hole Z have a hole depth of 9 to 11 m and a perforation angle of 78° to 85°.

[0023] 3) The main gun hole, buffer hole and pre-splitting hole are all filled with explosives, and the empty hole K is not filled with explosives.

[0024] The charge structure in the pre-splitting hole is as follows: The charging section of the pre-splitting hole Y from top to bottom is successively a weakening section, a normal section, and a strengthening section. The explosives include weakening-section latex explosive 6, normal-section latex explosive 7, strengthening-section latex explosive 9, detonating cord 8, upper digital electronic detonator 5, and lower digital electronic detonator 10; the weakening-section latex explosive 6 is installed in the weakening section, the normal-section latex explosive 7 is installed in the normal section, and the strengthening-section latex explosive 9 is installed in the strengthening section. The weakening-section latex explosive 6, normal-section latex explosive 7, and strengthening-section latex explosive 9 are fixed on a long strip of bamboo sheet 1 or wooden sheet from top to bottom, and can be fixed by winding PVC adhesive tape around the bamboo sheet 1 or wooden sheet. The upper end of the detonating cord 8 is connected in the forward direction to the upper digital electronic detonator 5, and the lower end is also connected in the forward direction to the lower digital electronic detonator 10; the detonator slots 2 and detonator leg wires 4 of the two digital electronic detonators are led out to the ground surface for connection of the detonation network, and the upper and lower ends of the detonating cord 8 are respectively closed by the way of casual connection. It is preferred that two detonating cords 8 are used, and both are connected in the forward direction to the upper digital electronic detonator 5 and the lower digital electronic detonator 10 respectively. The upper end of the detonating cord 8 is tied to the upper digital electronic detonator 5 and the weakening-section latex explosive 6, the lower end is tied to the strengthening-section latex explosive 9 and the lower digital electronic detonator 10, and the middle part is tied to the normal-section latex explosive 7. Through tying the detonating cord 8, it is fixed to the upper digital electronic detonator 5, weakening-section latex explosive 6, normal-section latex explosive 7, strengthening-section latex explosive 9, and lower digital electronic detonator 10, so that all the explosives are fixed on the bamboo sheet 1 or wooden sheet.

[0025] The charge amount Q of the pre-splitting hole 预 = 24 - 30 kg, the linear charge density q of the pre-splitting hole 线 = 2000 - 2500 g / m, the charging length L of the pre-splitting hole 药 = Q 预 / q 线 ; The charging length L of the normal section of the pre-splitting hole 正药 is 80% - 85% of the total charging length L of the pre-splitting hole 药 , the charging length L of the strengthening section of the pre-splitting hole 加药 and the charging length L of the weakening section 减药 are respectively 7.5% - 10% of the total charging length L of the pre-splitting hole 药 ; The charge amount of the normal section of the pre-splitting hole is Q 正 = q 线 ×L 正药 , the charge amount Q of the strengthening section 加 = 2×q 线 ×L 加药 ~5×q 线 ×L 加药 , the charge amount Q of the weakening section 减 = 0.45×q 线 ×L 减药~0.55×q 线 ×L 减药 Preferably, the charge amount Q of the weakening section is 减 =0.5×q 线 ×L 减药 。

[0026] The filling density inside the main blast holes is 0.83 - 0.87 g / cm 3 of the porous granular ammonium nitrate fuel oil explosive. Digital electronic detonators and primer cartridges are used to detonate the explosive. The leg wires of the digital electronic detonators and the card slots are led out to the ground surface for connecting the detonation network. A spacer is set at a position 4 - 5 m below the orifice of the main blast holes, and the upper part of the spacer is firmly filled with rock powder. At the same time, the delay time of the first detonating hole in the first row of the main blast holes is set to 100 ms, the interval time between the main blast holes in the same row is 42 ms, and the interval time between rows is 100 ms. The equal-time line is used for hole-by-hole detonation.

[0027] The filling density inside the buffer holes is 0.83 - 0.87 g / cm 3 of the porous granular ammonium nitrate fuel oil explosive. Digital electronic detonators and primer cartridges are used to detonate the explosive. The leg wires of the digital electronic detonators and the card slots are led out to the ground surface for connecting the detonation network. Spacers are respectively set at positions 3.5 - 4 m below the orifice of the 10 m buffer holes and 3 - 3.5 m below the orifice of the 6 m buffer holes, and the upper parts of the spacers are firmly filled with rock powder. At the same time, the delay time of the first detonating hole in the first row of the buffer holes is set to 100 ms, the interval time between the buffer holes in the same row is 42 ms, and the interval time between rows is 100 ms. The equal-time line is used for hole-by-hole detonation.

[0028] 4) Both the presplitting hole Y and the empty hole K are provided with spacers at positions 2 - 3 m below the orifice. The upper parts of the spacers are firmly filled with rock powder, forming a presplitting hole filling section 3 in the presplitting hole Y and an empty hole filling section 11 in the empty hole K. The filling lengths L of both the presplitting hole filling section 3 and the empty hole filling section 11 are not less than 1.5 times the hole diameter D of the presplitting hole, that is, L ≥ 1.5D. In this way, the presplitting hole Y from top to bottom is successively the presplitting hole filling section 3, the weakening section provided with the weakening section latex explosive 6, the normal section provided with the normal section latex explosive 7, and the strengthening section provided with the strengthening section latex explosive 9; the empty hole K from top to bottom is successively the empty hole filling section 11 and the empty hole section 12.

[0029] 5) After adopting the above blasting structure, by setting a slightly larger diameter empty hole without charge between the presplitting holes to guide the release of the blast shock wave of the presplitting holes; by changing the charge structure of the presplitting holes and using the precise delay of the digital electronic detonators to detonate the strengthening section explosive and the weakening section explosive simultaneously, increasing the instantaneous detonation energy; by adjusting the filling heights of the presplitting holes and the empty holes, reasonably reducing the discharge of the explosive energy from the presplitting holes and releasing it through the empty holes, the utilization rate of the explosive energy can be further improved, and the impact damage of the explosive to the reserved slope can be reduced.

[0030] This pre-splitting blasting method for reverse-inclined broken slopes adopts the above-mentioned blasting structure. During blasting, the pre-splitting holes are detonated simultaneously with a 0 ms delay. Specifically: 1) The pre-splitting holes Y are detonated simultaneously with a 0 ms delay; the upper digital electronic detonators 5 and the lower digital electronic detonators 10 of the pre-splitting holes Y are instantaneously detonated, and are conducted through the detonating cord 8 to make the reduced-section latex explosives 6, the normal-section latex explosives 7, and the enhanced-section latex explosives 9 detonate simultaneously.

[0031] 2) The delay time of the first detonating hole in the first row of the main blast holes is set to 100 ms, the interval time between the main blast holes in the same row is 42 ms, and the interval time between rows is 100 ms. Isochronous line-by-hole detonation is adopted.

[0032] 3) After two rows of the main blast holes are blasted, the first detonating hole in the first row of the buffer holes detonates with a 100 ms delay, the interval time between the buffer holes in the same row is 42 ms, and the interval time between rows is 100 ms. Isochronous line-by-hole detonation is adopted.

[0033] Example: Taking the blasting of the reverse-inclined broken slope in the Sijiaying stope as an example for illustration, it is specifically described as follows.

[0034] 1. Blasthole structure design: Figure 1 As shown, first, according to the actual situation of mine production, the bench height is determined to be 15 m. A φ150 type down-the-hole drill commonly used in mine exploitation is selected to drill the pre-splitting holes, and a φ200 type down-the-hole drill is selected to drill the empty holes. The relevant parameters of other pre-splitting holes, empty holes, buffer holes, and main blast holes are determined as follows: 1) Determine the distance J between the pre-splitting hole and the empty hole: According to the multiple blasting practices of our unit, based on the bench height H = 15 m, the drilling angle α = 65°, the blasthole depth L = H / sinα = 15 / sin65° ≈ 16 m, and the diameter D of the pre-splitting hole = (150 - 165) mm, 150 mm is taken this time; the distance J between the pre-splitting hole and the empty hole = (8 - 12)D ≈ (1.2 - 1.8) m. To ensure effective penetration between the pre-splitting hole and the empty hole, the distance J between the pre-splitting hole and the empty hole in this blasting takes the minimum value of 1.2 m; the hole spacing J of the pre-splitting hole 预 =(16 - 24)D ≈ (2.4 - 3.6) m. The hole spacing J of the pre-splitting hole in this blasting 预 takes the minimum value of 2.4 m.

[0035] 2) Determine the stemming length L of the pre-splitting hole: According to the mining manual, the hole mouth of 1 - 1.5 m is not charged for stemming. At the same time, due to the special geographical location of our mining area, the phenomenon of blasting out is not allowed. Therefore, to ensure safety, the stemming length L of the pre-splitting hole should be greater than 1.5 times the blasthole diameter as the stemming length, L = 1.5D = 1.8 m. In this case, according to the actual blasting experience on site, no blasting out phenomenon will occur when taking the larger value of 3 m.

[0036] 3) Determine the decoupling coefficient X: The decoupling coefficient refers to the situation where the diameter of the charge is smaller than the diameter of the blast hole, and there is a gap between the charge and the blast hole wall. Considering the actual production, the drilling diameter D is equal to 150 mm, and the cartridge diameter D_charge is equal to 70 mm. That is: the decoupling coefficient X = D / D_charge = 2.1.

[0037] 4) Determine the linear charge density Δ: The linear charge density refers to the ratio of the charge amount in a single hole to the charge length. Usually, the charge amount in the bottom 1 m hole should be larger than the linear charge density in the upper part. According to the excavation example of the road cut in Baoshan Copper Mine in the mining manual, the linear charge density Δ of the presplitting holes with a D150 mm hole diameter should be between 0.8 and 1.2 kg / m. In this design, it is taken as 0.9 - 1.1 kg / m.

[0038] Since Q 预 = q 线 L 药 , where: the charge amount Q of the presplitting hole 预 = 24 - 30 kg, and 25 kg is taken in this case; the linear charge density q of the presplitting hole 线 = 2000 - 2500 g / m, and 2000 g / m is taken in this case; the charge length L of the presplitting hole 药 = 12 m. For the normal section, the charge amount of the latex explosive Q 正 = q 线 L 正药 = 2000×10 = 20 kg, and L 正药 is taken as 10 m for the normal section; for the enhanced section, the charge amount of the latex explosive Q 加 =(2 - 5)×q 线 L 加药 = 2×2000×1 = 4 kg, and L 加药 is taken as 1 m for the enhanced section. In this case, 2 times q 线 is taken; for the weakened section, the charge amount of the latex explosive Q 减 = 0.5×q 线 L 减药 = 0.5×2000×1 = 1 kg, and L 减药 is taken as 1 m for the weakened section. In this case, 0.5 times q 线 is taken; Q 预 = Q 正 + Q 加 + Q 减 = 20 + 4 + 1 = 25 kg.

[0039] 5) Determine the diameter of the empty hole: According to the experimental analysis, the larger the diameter of the empty hole, the better the effect after presplitting blasting. However, considering the special situation of the mine operation site, the maximum that can be selected is the D200 down-the-hole drill for slope perforation operation. Therefore, the diameter of the empty hole Kd = 200 mm in this experiment.

[0040] The determined parameters of the presplitting holes and the empty holes are shown in Table 1; Table 1: Parameters of Presplitting Holes and Empty Holes

[0041] 6) Determine the buffer hole parameters: In the pre-splitting blasting of high-steep slopes, the design of buffer holes is particularly important. How to select relatively reasonable buffer parameters determines the success of slope pre-splitting blasting. The design of two rows of buffer holes in this design is shown in Table 2 below; Table 2: Buffer hole parameters

[0042] 7) Determine the main blast hole parameters: The blast holes in the front row of buffer holes are all main blast holes. The depth of the main blast holes is equal to the bench height and no overbreak is set. In order to ensure the pre-splitting blasting effect, it is best to preset two rows of main blast holes and the front row of main blast holes is all for slag cleaning. The main blast holes are drilled vertically without setting an angle to avoid affecting the drilling quality and the density of charge; the parameters of the main blast holes are shown in Table 3; Table 3: Main blast hole parameters

[0043] 8) This blasting method adopts the above-mentioned blast hole structure. In the pre-splitting blast holes, latex explosives, detonating cords, bamboo splitters, and digital electronic detonators are loaded. The digital electronic detonators are detonated simultaneously with a 0 ms delay in the holes to ensure that the explosives in the upper and lower parts of the pre-splitting holes are detonated simultaneously.

[0044] 2. Blasting and implementation: The location of the blasting experiment is at the -127 m level of the south slope. The south slope is an anti-dip rock formation, and the main lithologies are moderately weathered biotite granulite, quartz sandstone, magnetite quartzite, etc. The uniaxial compressive strength of the rock is between 44.89 and 84.96 MPa; the internal friction angle is between 39° and 60°; the cohesion is between 0.7 and 2.1 MPa. In the experiment, two rows of main blast holes are arranged, with 10 holes in the first row and 9 holes in the second row; two rows of buffer punching holes are arranged, with 8 holes in the first row and 7 holes in the second row. There is a total of one row of pre-splitting holes and empty holes, including 9 pre-splitting holes and 8 empty holes. A total of 51 blast holes are set, arranged in five rows, and the hole layout method is a plum blossom-shaped layout. Among them, 43 blast holes are charged and 8 empty holes are not charged. The explosives for the pre-splitting holes are Shandong Tianbao No. 2 rock emulsion explosives; the main blast holes and buffer holes are detonated with porous granular ammonium oil and Shanxi Jiangyang detonators. The entire network connection is carried out using Qianjin Minbao digital electronic detonators for connection and detonation time setting to ensure the accuracy of the network detonation time. The charge per meter of the φ150 down-the-hole drill blast hole Q single = ρπr 2 = 0.85×3.14×7.52≈15 kg; where ρ is the explosive density, and the ammonium oil explosive generally takes 0.81 - 0.85 g / cm 3 , 0.85 g / cm is taken in this case 3 , and r is the radius of the blast hole.

[0045] The first row and the second row of main blast holes: The diameter of the blast hole D1 = 150 mm, hole depth L 1 = 16 m, row spacing b 1 = 4 m, hole density coefficient m = 0.8 - 1.4, hole spacing a1 = mb 1 = 1×4 = 4 m, overbreak depth l 1 = 1 m, stemming height h 1 =(30 - 40)D 1 = 33×0.15 = 4.5 m, powder factor q 1 = 0.6 - 0.85 = 0.76 kg / m 3 , the total charge of the main blast holes in the first row and the second row is based on Q 1 = q 1 a 1 b 1 L 1 ×7 = 0.76×4×4×16×19 = 3697 kg.

[0046] The third row and the fourth row of buffer holes: blast hole diameter D 2 = 150 mm, hole depth L 2 = 10 m, 6 m, row spacing b 2 = 4 m, hole density coefficient m = 0.8 - 1.4, hole spacing a 2 = mb 2 = 1×4 = 4 m, overbreak depth l2 = 1 m, stemming height h 2 =(30 - 40)D 2 = 33×0.15 = 4.5 m. According to the actual on-site blasting experience, the stemming of the 10 m buffer holes is taken as 4 m, and the stemming of the 6 m buffer holes is taken as 3 m. The powder factor q 2 = 0.6 - 0.85 kg / m 3 are taken as 0.56 kg / m 3 、0.47 kg / m 3 , the total charge of the third row and the fourth row of buffer holes is based on Q 2 = q 2 a 2 b 2 L 2 ×8 = 0.56×4×4×10×8 = 717 kg、Q 2 = q 2 a 2 b 2 L 2 ×7 = 0.47×4×4×6×7 = 316 kg.

[0047] The fifth row of presplitting holes and relief holes: presplitting hole diameter D 3 = 150 mm, relief hole diameter D 4 = 200 mm, presplitting hole and relief hole depth L 3= 16m, hole spacing b3 = 1.2m. The stemming height is greater than 1.5 times the hole diameter. Taking the larger value of 3m according to actual blasting experience, decoupling coefficient X = D / D 药 = 2.1. The linear charge density Δ in this design is taken as 1 kg / m between 0.9 and 1.1 kg / m, and the cartridge diameter is taken as 70 mm (specification length 330 mm, weight 1 kg). For the strengthening section of 1 m, the charge per meter is 3 kg; for the normal section of 8 m, the charge per meter is 1 kg; for the weakening section of 4 m, the charge per meter is 0.5 kg. The total charge of the presplitting holes is based on Q 3 =(strengthening section × 1 + normal section × 8 + weakening section × 4) × 9 = (3 + 8 + 2) × 9 = 117 kg.

[0048] The total charge of this experiment Q 总 = Q 1 + Q 2 + Q 2 + Q 3 = 3697 + 717 + 316 + 117 = 4847 kg. The presplitting holes are initiated instantaneously by digital electronic detonators, and the main blast holes and buffer holes are initiated by digital electronic detonators with millisecond differential hole-by-hole initiation. During blasting, the presplitting holes are initiated first, and the energy is released along the empty holes. An obvious presplitting crack is formed between the presplitting holes and the empty holes. The forward movement of the main blast holes is obvious, so that the blasting energy is released along the throwing direction. Under the buffering effect of the buffer holes, the impact of the explosive energy on the reserved slope surface is small, reducing the damage degree of the explosive explosion to the reserved slope surface. Through subsequent observation and analysis of the operation of the special slope-cutting and boundary-leaning hook machine, using the empty holes as the free surface for the release of explosive energy and changing the charge structure of the presplitting holes, the presplitting surface is obviously smooth and flat after blasting, with less crushed stones and floating stones, effectively protecting the surrounding rock, reducing overbreak, increasing the hole trace rate, reducing the subsequent slope treatment cost and ensuring the safety of personnel and equipment operation.

[0049] This blasting structure and method change the charge structure of the presplitting holes and set an empty hole between every two presplitting holes as the free surface for the release of explosive energy. At the same time, a digital electronic detonator initiation network is adopted to ensure the instantaneity of the initiation of the presplitting holes, ensuring that other blast holes can achieve true millisecond differential hole-by-hole initiation. By using the empty holes without filling explosives, the damage degree of the rock mass around the empty holes is small, and the stability of the presplitting surface after blasting is strong. It overcomes the characteristic that it is difficult to ensure the slope smoothness in traditional presplitting blasting and solves the problem of great damage to the slope in presplitting blasting in jointed and fractured rocks. It is technologically advanced, simplifies the process, has a lower cost than conventional presplitting blasting, has obvious technical advantages, remarkable social and economic benefits, meets the requirements of modern intelligent mine construction, has strong market competitiveness, and can be applied to metal and non-metal mines with broad prospects.

Claims

1. A reverse-tilt broken slope pre-splitting blasting structure, characterized in that: The invention comprises pre-splitting holes (Y) and empty holes (K); the pre-splitting holes (Y) are arranged in a row on the designed boundary slope line, and the empty holes (K) are arranged between adjacent pre-splitting holes (Y); the pre-splitting holes (Y) are filled with explosives, and the empty holes (K) are not filled with explosives.

2. The reverse-tilt crushing slope pre-splitting blasting structure according to claim 1 is characterized by: The empty hole (K) is arranged at a middle position between adjacent pre-splitting holes (Y).

3. The reverse-tilt crushing slope pre-splitting blasting structure according to claim 1 is characterized by: As mentioned above, the diameter of the empty hole (K) is 4 / 3 to 5 / 3 of the diameter of the pre-crack hole (Y).

4. The reverse-tilt crushing slope pre-splitting blasting structure according to claim 1 is characterized by: The hole spacing of the pre-crack holes (Y) is 16 to 24 times the hole diameter thereof.

5. The reverse-tilt crushing slope pre-splitting blasting structure according to claim 1 is characterized by: The charge sections of the pre-splitting hole (Y) are, from top to bottom, a weakened section, a normal section and a reinforced section; the explosives include a weakened section latex explosive (6), a normal section latex explosive (7), a reinforced section latex explosive (9), a detonating cord (8), an upper digital electronic detonator (5) and a lower digital electronic detonator (10); the upper part of the detonating cord (8) is positively connected to the upper digital electronic detonator (5), and the lower part is positively connected to the lower digital electronic detonator (10).

6. The reverse-tilt crushing slope pre-splitting blasting structure according to claim 5 is characterized by: The charge length of the normal section of the pre-crack hole is 80% to 85% of the total charge length of the pre-crack hole, and the charge lengths of the reinforced section and the weakened section of the pre-crack hole are respectively 7.5% to 10% of the total charge length of the pre-crack hole; the charge amount per unit length of the reinforced section is 2 to 5 times the charge amount per unit length of the normal section of the pre-crack hole, and the charge amount per unit length of the weakened section is 0.45 to 0.55 times the charge amount per unit length of the normal section of the pre-crack hole.

7. The reverse-tilt crushing slope pre-splitting blasting structure according to claim 1 is characterized by: The pre-crack hole (Y) and the empty hole (K) are both provided with spacers 2 to 3 m below the hole mouth, and the upper part of the spacers is filled to form a filling section; the length of the filling section of the pre-crack hole (Y) and the empty hole (K) is not less than 1.5 times the blasthole diameter of the pre-crack hole.

8. A reverse-tilt crushing slope pre-splitting blasting structure according to any one of claims 1 to 7, characterized in that: Two rows of buffer holes (H) are provided between the main gun port (Z) and the pre-splitting port (Y).

9. A method for pre-splitting blasting of reverse-tilt broken slopes, using the blasting structure according to any one of claims 1 to 8, characterized in that: The pre-crack holes (Y) are detonated simultaneously with a delay of 0 ms.

10. A method for pre-splitting blasting of reverse-tilt broken slopes according to claim 9, characterized in that: The main gun holes (Z) are detonated hole by hole in isochronous lines, and the buffer holes (H) are detonated hole by hole in isochronous lines; the first detonation hole in the first row of the main gun holes (Z) is detonated with a delay of 100ms.

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