Slow slope hole-by-hole presplitting blasting method and system

Abstract

The invention relates to the technical field of blasting construction, in particular to a slow slope hole-by-hole presplitting blasting method and system.The method comprises the following steps that engineering geological condition comprehensive information of a blasting area is obtained so as to determine the blast hole distance, the blast hole row distance, the blast hole depth and blasting delay; in the blasting area, RTK is used for paying off and measuring points, the coordinates of the blast holes are obtained in combination with the three-dimensional point cloud data, the distance between the blast holes and the row distance between the blast holes and used for positioning the blast holes and searching the holes, and drilling is completed according to the depth of the blast holes; charging explosives into the blast holes, checking the connection of a detonating network, detonating according to the sequence of the pre-split holes, the main blasting holes and the auxiliary holes, and performing hole-by-hole short-delay detonating on the pre-split holes according to the blasting delay; and field blasting is carried out in the blasting area, the vibration reduction rate of hole-by-hole presplitting blasting is calculated, the half-hole rate after hole-by-hole presplitting blasting is counted, and the damage degree of the surrounding rock is judged. According to the method, joint development during slow slope hole-by-hole presplitting blasting can be effectively reduced, the slope stability of fractured rock mass and surrounding buildings is improved, and the slope protection cost is saved.

Description

Technical Field

[0001] This invention relates to the field of blasting construction technology, and in particular to a method and system for pre-splitting blasting of gentle slopes using a hole-by-hole approach. Background Technology

[0002] With the continuous development of open-pit mining and engineering construction in my country, pre-splitting blasting excavation projects present complex environments such as high slopes, weak and fractured rock strata, and facilities requiring protection around the blasting area. In these situations, the urgent need for high-quality and safe pre-splitting blasting becomes particularly prominent. Under the condition of implementing safe and high-quality pre-splitting blasting in complex environments, it is required that the vibration of pre-splitting blasting and the damage to the retained rock mass must be controlled within safe limits. Because the pre-splitting holes are arranged on the perimeter outline, directly facing the retained rock mass, and detonating first, there is only one free face during the blasting of the pre-splitting holes. Both the retained rock mass and the rock mass to be blasted are essentially infinite rock masses relative to the pre-splitting holes. After the explosive in the pre-splitting holes detonates, the energy is released randomly, causing damage to both the retained rock mass and the rock mass to be blasted. Despite the use of small-diameter holes and weak charge (interval charging) for the pre-splitting holes, the blasting vibration generated by the superposition of explosive stress waves during the simultaneous detonation of multiple holes in the pre-splitting row still causes varying degrees of damage and destruction to the remaining rock mass, alters the original rock stress state, and causes deterioration of the rock mass's mechanical properties, posing a threat to safe production.

[0003] Traditional theory and practice have proven that the optimal pre-splitting blasting effect is achieved when all boreholes are detonated simultaneously. However, the complex construction environment requires control over the maximum single-shot charge of pre-splitting blasting. This necessitates the segmented detonation of all pre-splitting boreholes during pre-splitting blasting, ensuring one shot per borehole. This affects the effectiveness of pre-splitting blasting, and the inter-hole delay also alters the traditional pre-splitting blasting mechanism and changes the destructive effect of pre-splitting blasting.

[0004] For blasting techniques in complex environments such as high slopes, weak and fractured rock strata, and surrounding facilities requiring protection, if the slope angle is large (greater than 70°), not only is the slope itself fractured, with well-developed and fractured rock joints and weak rock, but it is also affected by external environmental factors such as blasting disturbance, earthquakes, and rainfall. Large-angle slopes are prone to collapse, and open-pit slope collapses can easily cause large-scale landslides on steps, severely impacting personnel safety, damaging machinery and equipment, and destroying large pumping stations, requiring work stoppages for rectification, seriously affecting mine production. Furthermore, significant financial and material resources are needed for subsequent slope treatment, increasing economic costs. Therefore, it is necessary to reduce the slope angle to ensure that the slope is less prone to landslides. However, there is currently no complete system for selecting pre-splitting blasting parameters for gentle slopes. Traditional pre-splitting blasting uses initiation detonation, and although it employs small-charge cartridges and air-gap charging, the large amount of explosives used in simultaneous detonation of multiple holes still easily damages the remaining rock mass and surrounding structures. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method and system for pre-splitting blasting of gentle slopes using a hole-by-hole approach.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a method for pre-splitting blasting of gentle slopes, comprising the following steps: conducting a geological survey of the blasting area and determining comprehensive information on the engineering geological conditions of the blasting area, thereby determining four drilling and blasting parameters: borehole spacing, borehole row spacing, borehole depth, and blasting delay; using RTK line setting and measuring points within the blasting area, combined with the three-dimensional point cloud data of the blasting area, the borehole spacing, and the borehole row spacing to obtain borehole coordinate data; importing the borehole coordinate data into the operation control system of an intelligent drilling rig, performing borehole positioning and locating based on the intelligent positioning system on the intelligent drilling rig, and completing drilling according to the borehole depth; loading explosives into the boreholes and checking the connection of the detonation network, and detonating the boreholes sequentially in the order of pre-splitting holes, main blasting holes, and auxiliary holes, wherein the pre-splitting holes are detonated with short delays according to the blasting delay; conducting on-site blasting in the blasting area, calculating the vibration reduction rate of the pre-splitting blasting, and simultaneously calculating the half-hole rate and judging the degree of damage to the surrounding rock after the pre-splitting blasting. This invention can effectively reduce joint development during hole-by-hole pre-splitting blasting of gentle slopes, improve the slope stability of fractured rock masses and surrounding buildings, and save on slope protection costs.

[0007] Optionally, the step of conducting a geological survey of the blasting area and determining comprehensive information on the engineering geological conditions of the blasting area, and then determining four drilling and blasting parameters—borehole spacing, borehole row spacing, borehole depth, and blasting delay—includes the following steps: A geological survey of the blasting area was conducted to determine the comprehensive information on the engineering geological conditions of the blasting area. The comprehensive information on geological conditions included mining parameters, borehole diameter, and rock mechanics parameters. The spacing between boreholes in the same row is determined based on the borehole diameter. The auxiliary holes and the main blasting holes are evenly distributed in the rock mass of the main blasting area, and the hole spacing is determined by adjusting and optimizing the hole profile design drawing. The depth of the blast hole is determined based on the mining parameters of the mining area and the trigonometric function calculation method, including the depth of the pre-splitting hole, the depth of the auxiliary hole and the depth of the main blast hole; Based on the rock mechanics parameters, and taking into account the duration of the detonation wave inside the hole, the duration of the explosion stress wave between the holes, and the strength of the medium during the explosive explosion, the blasting delay is calculated.

[0008] Optionally, the depth of the pre-cracked hole satisfies the following relationship: Where L is the depth of the pre-splitting hole, H is the height of the blasting zone step, and h is the extra depth. The perforation angle for the pre-cracked hole.

[0009] Optionally, the depth of the auxiliary hole satisfies the following relationship: in, The depth of the auxiliary holes in the i-th row is [the depth of the auxiliary holes]. The distance between the pre-cracked hole and the auxiliary holes in the i-th row is given. To ensure the vertical safety distance between the bottom of the auxiliary hole and the pre-cracked surface, The slope angle of the step.

[0010] Optionally, the depth of the main blast hole satisfies the following relationship: in, H represents the depth of the main blast hole, and H represents the height of the blast zone step.

[0011] Optionally, the blasting delay satisfies the following relationship: in, The length of the explosive charge inside the borehole. Let be the propagation speed of the detonation wave, and n be the ratio of the crack depth to its length. The spacing between pre-cracked holes, The longitudinal wave velocity of the stress wave in the rock. For the blasting delay, The radius of the borehole is... This is the critical size of the crack.

[0012] Optionally, the steps of entering the fractured rock mining area after blasting to check the size of the blasted blocks and measure the width of the pre-cracks, and to statistically analyze the half-wall porosity and calculate the vibration reduction rate include the following: Simultaneous pre-splitting blasting and hole-by-hole pre-splitting blasting were carried out in the same blasting zone, and the measured vibration velocity under the two initiation methods was measured respectively, and then the vibration reduction rate of hole-by-hole pre-splitting blasting was calculated. After the pre-splitting blasting is completed, a 3D laser scanner is used to scan the slope surface to obtain images of the slope surface after blasting. Based on the original design depth of the pre-splitting holes, the reinforced, normal, and weakened charge sections and the filling section in the slope surface images are scaled down proportionally. The processed slope image is imported into CAD software, and the half-hole ratio of different charge sections is measured to obtain the half-hole ratio after pre-splitting blasting. The half-hole in each pre-splitting hole is divided into three regions according to the charging section and subjected to grayscale and binarization processing. The target region is covered with square grids. The fractal dimension is calculated by counting the number of boxes covering the cross section, and then the degree of damage to the surrounding rock is determined.

[0013] Optionally, the vibration reduction rate satisfies the following relationship: in, The vibration reduction rate is... The measured vibration velocity of the simultaneous pre-splitting blasting is given. The measured vibration velocity is the value of the pre-splitting blasting per hole.

[0014] Optionally, the fractal dimension satisfies the following relationship: in, Let fractal dimension be denoted as . The number of boxes covering the cross section. Let be the side length of the k-th square.

[0015] Secondly, the present invention provides a pre-splitting blasting system for gentle slopes, the pre-splitting blasting system for gentle slopes comprising: a data acquisition device, a data output device, a processor, and a storage device, the storage device comprising a computer-readable storage medium storing a computer program, the computer program comprising program instructions, the program instructions being executed by the processor to cause the processor to implement the pre-splitting blasting method for gentle slopes provided by the present invention.

[0016] The present invention has at least the following beneficial effects: 1. Based on the reasonable design of borehole spacing, borehole row spacing and borehole depth, this invention comprehensively considers factors such as the action time of the in-hole detonation wave and the inter-hole explosion stress wave during the explosive explosion, and the strength of the medium, and establishes an expression for the inter-hole delay time of pre-splitting blasting. This provides a basis for selecting the delay time of pre-splitting blasting in blasting areas with well-developed rock joints and fissures and complex surrounding structures. 2. This invention, through the rational design of four drilling and blasting parameters—borehole spacing, borehole row spacing, borehole depth, and blasting delay—can effectively improve slope stability in complex environments with well-developed joints, fractured rock masses, and surrounding buildings, thereby saving slope protection costs and reducing the cost of shotcreting concrete. 3. This invention provides a system adapted to the method, which can improve the practicality of the method and facilitate its promotion. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of a method for pre-splitting blasting of a gentle slope according to an embodiment of the present invention. Figure 2 This is a schematic plan view of the borehole arrangement according to an embodiment of the present invention; Figure 3 This is a schematic cross-sectional view of the borehole arrangement according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the superposition of stress waves in the pre-splitting blasting of the hole-by-hole initiation according to an embodiment of the present invention; Figure 5 The results of blasting vibration monitoring are from an embodiment of the present invention. Figure 6 This is a schematic diagram of the frame of a pre-splitting blasting system for gentle slopes according to an embodiment of the present invention. Detailed Implementation

[0019] Specific embodiments of the present invention will now be described in detail. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other instances, well-known circuits, software, or methods have not been specifically described to avoid obscuring the invention.

[0020] Throughout this specification, references to "an embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "in an embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale.

[0021] It should be noted in advance that, in one alternative embodiment, except for independent descriptions, the same symbols or letters appearing in all formulas have the same meaning and value.

[0022] In one optional embodiment, please refer to Figure 1 This invention provides a method for pre-splitting blasting of gentle slopes using a hole-by-hole method, the method comprising the following steps: S1. Conduct a geological survey of the blasting area and determine the comprehensive information on the engineering geological conditions of the blasting area, and then determine the four drilling and blasting parameters: borehole spacing, borehole row spacing, borehole depth, and blasting delay.

[0023] Step S1 specifically includes the following steps: S11. Conduct a geological survey of the blasting area and determine the comprehensive information on the engineering geological conditions of the blasting area. The comprehensive information on geological conditions includes mining parameters, borehole diameter, and rock mechanics parameters.

[0024] Specifically, in this embodiment, the lithology of the blasting area is mainly argillaceous limestone and sandy limestone, with poor rock mass integrity and homogeneity, well-developed joints and fissures, and weak interlayers in some areas, making blasting moderately difficult. The mining method in the blasting area is open-pit mining, with designed bench height, safety platform width, cleaning platform width, and bench slope angle of 15m, 5m, 8m, and 45°~55° respectively. The diameter of the pre-splitting holes in the blasting area is 0.115m, and the diameter of the remaining blast holes is 0.14m. The hole spacing in the main blasting area is 6m × 4m. The main rock mechanical parameters of the lithology and rock mass in the blasting area are shown in Table 1.

[0025] Table 1. Lithological and engineering geological conditions of the test area S12 determines the spacing between boreholes in the same row based on the borehole diameter.

[0026] The borehole coordinate data is imported into the operation control system of the intelligent drilling rig. Based on the intelligent positioning system on the intelligent drilling rig, the borehole is automatically located and searched. During the drilling process, the intelligent drilling rig can adjust the depth and drilling angle of the borehole according to the sensor data, and complete the drilling according to the borehole depth.

[0027] Specifically, in this embodiment, please refer to Figure 2 , Figure 2 The top row of blast holes consists of pre-splitting holes, followed by rows of auxiliary holes (first row, second row, third row) and main blasting holes. The spacing between pre-splitting holes in the fractured rock mass... It is generally expressed as a multiple of the pre-splitting hole diameter D, and is calculated as follows: Calculations show that The value range is 0.92m to 1.15m, and 1.0m was used in subsequent blasting tests. Auxiliary hole spacing. , , and the distance between the main blast holes A similar method can also be used to obtain it.

[0028] S13. The auxiliary holes and the main blasting holes are evenly distributed in the rock mass of the main blasting area, and the hole spacing is determined by adjusting and optimizing the hole profile design drawing.

[0029] Specifically, in this embodiment, the borehole spacing is one of the main parameters affecting the blasted block size and blast pile shape. A large spacing results in larger block size, while a small spacing leads to higher drilling costs, increased explosive charge, and higher blasting material costs. Therefore, a suitable borehole spacing is beneficial for improving blasting effects and reducing blasting costs. In this embodiment, the borehole spacing is mainly used to improve the effect of the main blasting zone, thus primarily targeting auxiliary holes and main blasting holes.

[0030] Please see Figure 3 The main principle for the spacing of auxiliary and main blasting holes is to ensure sufficient fracturing of the rock mass on the outer side of the slope after blasting. To achieve this effect, auxiliary and main blasting holes can be evenly distributed within the rock mass of the main blasting zone to guarantee good fracturing and blast pile effects. Through adjustments and optimizations in the borehole profile design drawing, the final spacing of all holes is as follows: , The spacing between the pre-cracked holes and the first row of auxiliary holes, The spacing between the first row of auxiliary holes and the second row of auxiliary holes. The row spacing between the second row of auxiliary holes and the third row of auxiliary holes, The row spacing between the third row of auxiliary holes and the last row of main blasting holes.

[0031] S14. Determine the depth of the blast holes based on the mining parameters of the mining area and the trigonometric function calculation method, including the depth of the pre-splitting holes, the depth of the auxiliary holes and the depth of the main blasting holes.

[0032] Specifically, in this embodiment, please refer to Figure 3 The depth of the pre-cracked hole can be calculated using trigonometric function formulas: Where L is the depth of the pre-splitting hole, H is the height of the blasting zone step, and h is the extra depth. The perforation angle for the pre-cracked hole.

[0033] In subsequent blasting tests, the perforation angle of the pre-splitting hole was taken as 55°. For fractured rock mass, in order to reduce the influence of over-depth on the height of the next step, over-depth was not considered, that is, h was taken as 0, and L was calculated to be 22.0m.

[0034] The arrangement of auxiliary holes should maintain certain characteristics. The bottom of the auxiliary hole should be 10 times the diameter of the pre-splitting hole; otherwise, they may be punctured, resulting in wasted explosives and poor blasting effect. Based on this principle, the depth of the auxiliary holes can be determined using trigonometric function calculation or drawing measurement. Generally, drawing measurement is more convenient and faster, suitable for pre-blasting indoor design, while trigonometric function calculation is suitable for calculating the depth of holes when temporarily arranging blast holes on site. This embodiment uses trigonometric function calculation to calculate the depth of the auxiliary holes, as shown in the following formula: in, The depth of the auxiliary holes in the i-th row is [the depth of the auxiliary holes]. Let be the distance between the pre-cracked hole and the i-th row of auxiliary holes. To ensure the vertical safety distance between the bottom of the auxiliary hole and the pre-cracked surface, The slope angle of the step. Generally, a depth of 1m to 1.5m is used, and then the result is calculated. , and The heights are 4m, 9.7m, and 15.4m, respectively.

[0035] The depth of the main blast hole is taken as the step height H plus the extra depth, that is: in, Let H be the depth of the main blast hole and H be the step height of the blast zone. The final calculated depth of the main blast hole is 16m.

[0036] S15. Based on the rock mechanics parameters, and taking into account the duration of the detonation wave inside the hole, the stress wave between the holes, and the strength of the medium during the explosive explosion, calculate the blasting delay.

[0037] Specifically, in this embodiment, the explosive detonates in the borehole, generating a detonation wave that propagates through the rock medium. The duration of the detonation in the borehole must be considered, as it depends on parameters such as the nature of the explosive, the scale of the blasted medium, the external environment, and the charge quantity. The propagation speed of the detonation wave in the rock medium is related to specific heat capacity and the density of the detonation products, and its calculation formula is as follows: in, The propagation speed of the detonation wave, For specific heat capacity, for an ideal gas It is usually between 1.2 and 1.5. For the detonation pressure at the leading edge of the detonation wave, The density of the detonation products.

[0038] During the charging process of the main blast hole, continuous cylindrical decoupled charges are mainly used, with decoupling coefficients mainly ranging from 1.5 to 3.0. The action time of the explosive in the medium satisfies the following relationship: in, This refers to the length of the explosive charge inside the borehole.

[0039] When a radially decoupled charge is used, the borehole wall is uniformly subjected to the initial pulse peak pressure of the explosive detonation, i.e., the initial detonation pressure is: in, Initial detonation pressure, , These are the density and detonation velocity of the explosive, respectively. d is the diameter of the emulsion explosive cartridge, m is the borehole diameter, and m is the pressure amplification factor of the collision between the detonation products and the borehole wall, which is generally taken as 8 to 11.

[0040] After explosives detonate in a rock medium, the radial cracks resulting from the propagation and development of internal rock cracks are mainly caused by the initial detonation pressure of the explosive. The magnitude of the initial detonation pressure is negatively correlated with the stress wave propagation distance. When the stress wave propagates to a certain point, the peak radial compressive stress at that point... It can be represented as: in, The distance is the ratio of the distance from the center of the charge to the radius of the borehole. , This is the actual distance from the center of the charge to that point. The radius of the borehole is... The stress wave attenuation coefficient is... , The dynamic Poisson's ratio of the rock. , is the static Poisson's ratio for rock materials.

[0041] Peak tangential tensile stress in rock medium under radial stress Represented by the peak value of radial compressive stress: Assuming that the initial crack in the rock material, or the initial crack generated by explosives, is only subjected to tensile stress, and the stress wave continues to act, causing the crack to propagate and eventually form a type I crack, the pressure strength factor at this point is: As the stress wave continues to act, when the tangential tensile stress exceeds the dynamic tensile strength of the rock... At this point, a new initial crack forms, and the crack length r of the initial radial crack can be estimated using the initial detonation pressure, i.e.: Under external loads, the original crack and newly formed cracks in rock-like materials continuously propagate. When the stress intensity factor at the crack tip equals the fracture toughness of the rock, the crack reaches an unstable propagation state. At this point, the crack length is the critical size. Even if no further external load is applied, newly formed cracks will continue to propagate because their stress intensity factor exceeds the fracture toughness of the rock, eventually forming fissures of varying lengths within the rock. After multi-hole sequential detonation, a pre-crack or a fracture zone is formed. According to linear elastic fracture mechanics, the stress intensity factor is: in, For geometric shape factor, For long-range stress. It is usually taken as 1.12. Take the stress on the detonation wave front. .

[0042] For brittle materials like rocks, as the crack tip compressive strength factor increases to the fracture toughness of the rock material... At that time, that is At that time, the crack propagation length is equal to the critical size, that is... Ultimately, the critical size of the crack can be obtained. satisfy: In pre-splitting blasting with sequential hole initiation, when the first hole is blasted alone, an explosive pressure wave is generated under the action of the explosive. This stress wave acts on the rock medium, forming an initial radial crack. The continued action of the stress wave causes the crack to propagate and extend to the critical crack size. The final crack length can be expressed as: like Figure 4 As shown in (a1) and (a2), in the dynamic caustic test, during the delayed detonation between boreholes A and B, in order to form a "hook-like" crack convergence zone between the boreholes, when the crack generated in the first detonated borehole expands to the critical crack, the stress wave generated in the second detonated borehole just propagates to the tip of the crack in the first detonated borehole. At this time, the crack shifts under the continuous action of the stress wave, and the cracks generated by the two boreholes converge. Therefore, the blasting delay time between the two boreholes... for: in, The longitudinal wave velocity of the stress wave in the rock is denoted as .

[0043] like Figure 4 As shown in (b1) and (b2), when borehole A and borehole B are detonated simultaneously, the stress waves from the detonation between the boreholes will superimpose, thus forming a local high-pressure zone between the two boreholes, which may lead to excessive crack propagation or an expansion of the pulverized zone. Figure 4 As shown in (c1) and (c2), when the blasting delay between borehole A and borehole B is too short, the stress waves during the inter-bore initiation will still superimpose. To reduce the stress wave superposition effect during inter-bore initiation, the time interval for stress wave superposition should be avoided when selecting the delay time. Therefore, the minimum inter-bore delay time for pre-splitting blasting is defined as 12% of the P-wave propagation time between boreholes. Thus, the minimum inter-bore delay... To best satisfy: When explosives interact between boreholes, the resulting cracks interconnect and form an intersecting region. To reduce the severe blasting vibration caused by stress wave superposition, the delay time range between adjacent boreholes during pre-splitting blasting can be expressed as follows: .

[0044] Crack propagation in boreholes, influenced by the properties of the explosive and the rock medium, not only extends horizontally to form radial cracks, but also continues to extend towards the borehole depth, thus forming a pre-crack between two boreholes. Therefore, it is necessary to comprehensively consider the proportionality coefficient n between the crack propagation depth and length along the borehole depth direction. Its calculation formula is as follows: in, This represents the radial crack length.

[0045] Finally, taking into account factors such as the detonation wave inside the hole, the duration of the inter-hole explosion stress wave, and the strength of the medium during the explosive explosion, the blasting delay between pre-splitting blasting holes was obtained. The calculation formula solves the current problem of lacking a basis for selecting the delay time in complex environment applications of electronic detonators. It also addresses the blasting delay between boreholes in sequential pre-splitting blasting. The following relationship must be satisfied: Calculations show that for pre-splitting blasting in the soft rock area of ​​the blast zone, the delay time per hole is ≤ 0.003s. .

[0046] S2. Within the blasting zone, RTK is used to lay out lines and measure points, and the blasting zone's three-dimensional point cloud data, the blasting hole spacing, and the blasting hole row spacing are combined to obtain the blasting hole coordinate data.

[0047] Specifically, in this embodiment, the blasting area is divided into smaller cuboid regions of varying sizes, and RTK control points are set at the four corners of each region to obtain more accurate coordinate parameters. Within the blasting area, RTK is used for layout and measurement work. This operation yields transformation parameters from the International Geological System coordinate system to the Beijing 54 coordinate system, providing a parameter basis for subsequent point cloud coordinate transformation. RTK is a real-time dynamic differential positioning technology.

[0048] Import the control point coordinate data obtained from RTK into the AVC map software. At the same time, based on different geological conditions and the requirements for blasting accuracy, delineate the flight range of the drone within the blasting area and import the corresponding KML file into the drone remote control handle to ensure that the drone flies along the actual planned path.

[0049] During flight, the onboard lidar scans the explosion area below, quickly converting the scanned area into 3D point cloud data. This acquired 3D point cloud data is then imported into the drone's intelligent mapping software for initial model building, generating a complete 3D point cloud model, which is then further imported into LiDAR360 software for precision processing.

[0050] The processed 3D point cloud data is imported into 3DMine software to construct a digital terrain model, thus presenting the terrain conditions of the blasting area. Finally, using the blasting parameter design module in 3DMine software, the boreholes are arranged based on the known borehole spacing and borehole row spacing, and a borehole coordinate position report is generated to obtain the borehole coordinate data.

[0051] S3. Import the borehole coordinate data into the operation control system of the intelligent drilling rig, perform borehole positioning and borehole finding based on the intelligent positioning system on the intelligent drilling rig, and complete the drilling according to the borehole depth.

[0052] Specifically, in this embodiment, the borehole coordinate data is imported into the operation control system of the intelligent drilling rig, and the borehole is automatically located and searched based on the intelligent positioning system on the intelligent drilling rig. During the drilling process, the intelligent drilling rig can adjust the depth and drilling angle of the borehole according to sensor data, and then complete the drilling according to the preset borehole depth.

[0053] Furthermore, after drilling is completed, an intelligent borehole inspection robot is used to perform laser scanning on the borehole to determine the borehole depth, thereby completing the borehole inspection.

[0054] S4. Load explosives into the blast holes and check the connection of the detonation network. Detonate the holes one by one in the order of pre-splitting holes, main blasting holes, and auxiliary holes. The pre-splitting holes are detonated one by one with a short delay according to the blasting delay.

[0055] Specifically, in this embodiment, a high-precision intelligent charging trolley is used to complete the intelligent charging of the blast zone based on the borehole coordinate data. The charging method for the pre-splitting holes is decoupled air-gap charging. Small explosive cartridges and detonating cords are tied together with a flexible traction rope, and secured with a long cable tie, plastic-radius binding, nylon rope tensioner, and buckle seal. This binding method significantly shortens the charging time. The long cable tie, plastic-radius binding, nylon rope tensioner, and buckle seal can be purchased commercially; its length and width are 30cm and 5.2mm, respectively. The flexible traction rope is a commercially available packaging mesh sleeve for threaded parts, with a diameter of 40mm. The outer surface of the flexible traction rope has uniformly distributed small holes of the same size, which increases the friction between the explosive cartridges, detonating cords, and the mesh sleeve, preventing the explosive cartridges from slipping to the bottom of the hole and causing excessive local explosive charge, which could damage the surrounding rock.

[0056] More specifically, a long explosive string is formed by binding the explosives together with a flexible traction rope. The bottom section of the string is reinforced with explosives, accounting for approximately 50% of the total explosive charge in the hole; the middle section is normally loaded with explosives, accounting for approximately 30% of the total explosive charge in the hole; and the top section is weakened with explosives, accounting for approximately 20% of the total explosive charge in the hole. While ensuring the filling length, the length of the reinforced explosive section is taken as 0.2L, the length of the middle normal explosive section is 0.5L, and the total length of the top weakened explosive section and the filling section is 0.3L. The blasting delay is then calculated.

[0057] After loading the explosives and checking the detonation network connections, detonate the pre-splitting holes, main blasting holes, and auxiliary holes in sequence. Specifically, pre-splitting holes are detonated one by one with a short delay according to the calculated blasting delay.

[0058] Furthermore, after obtaining all drilling and blasting parameters through step S1, numerical simulation can be used to verify the blasting effect of the set drilling and blasting parameters on the blasting area, and on-site test blasting can be conducted in the blasting area to further verify the blasting effect. If the blasting effect is not up to standard, the drilling and blasting parameters need to be redesigned.

[0059] S5. Conduct on-site blasting in the blasting area, calculate the vibration reduction rate of pre-splitting blasting hole by hole, and at the same time, count the half-hole rate after pre-splitting blasting hole by hole and judge the degree of damage to the surrounding rock.

[0060] Step S5 specifically includes the following steps: S51. Simultaneous pre-splitting blasting and hole-by-hole pre-splitting blasting are carried out in the same blasting zone, and the measured vibration velocity under the two initiation methods is measured respectively, and then the vibration reduction rate of hole-by-hole pre-splitting blasting is calculated.

[0061] Specifically, in this embodiment, to verify the vibration reduction effect of sequential pre-splitting blasting, simultaneous pre-splitting blasting and sequential pre-splitting blasting can be performed in the blasting zone. The vibration velocities in the X, Y, and Z directions under both initiation methods are measured using a TC-4850 vibration meter, i.e., the measured vibration velocities. Of course, the vibration velocity in the main blasting zone can also be measured. The final measurement results are as follows: Figure 5 As shown, Figure 5 In the diagram, Method 1 represents simultaneous pre-splitting blasting, and Method 2 represents hole-by-hole pre-splitting blasting.

[0062] After measuring the actual vibration velocities under the two initiation methods, the vibration reduction rate of hole-by-hole pre-splitting blasting can be calculated according to the following formula: in, For vibration reduction rate, The measured vibration velocity for simultaneous pre-splitting blasting, The measured vibration velocity is for hole-by-hole pre-splitting blasting.

[0063] S52. After the pre-splitting blasting is completed, a 3D laser scanner is used to scan the slope surface to obtain images of the slope surface after blasting. The reinforced, normal, and weakened charge sections and the filling section in the slope surface images are scaled down proportionally with reference to the original design pre-splitting hole depth.

[0064] S53. Import the processed slope image into CAD software, measure the half-hole ratio of different charge sections, and thus obtain the half-hole ratio after pre-splitting blasting.

[0065] S54. Divide the half-hole in each pre-splitting hole into three regions according to the charging section and perform grayscale and binarization processing. Cover the target region with square grids. Calculate the fractal dimension by counting the number of boxes covering the cross section, and then determine the degree of damage to the surrounding rock.

[0066] Specifically, in this embodiment, the fractal dimension satisfies the following relationship: in, For fractal dimension, The number of boxes covering the cross section. Let be the side length of the k-th square.

[0067] The degree of damage is determined by the size of the fractal dimension. Generally, the larger the fractal dimension, the greater the degree of fractal fracture of the surrounding rock around the pre-fracturing hole, and the lower the half-hole ratio.

[0068] It should be noted that in some cases, the actions described in the specification can be performed in different orders and still achieve the desired results. In this embodiment, the order of steps is given only to make the embodiment clearer and easier to explain, and not to limit it.

[0069] In one optional embodiment, please refer to Figure 6 The present invention also provides a pre-splitting blasting system for gentle slopes, which includes: a data acquisition device 1, a data output device 2, a processor 3, and a storage device 4. The storage device 4 includes a computer-readable storage medium storing a computer program. The computer program includes program instructions, which, when executed by the processor 3, cause the processor 3 to perform the contents described in steps S1 to S5.

[0070] In summary, the present invention has at least the following beneficial effects: Based on the rational design of borehole spacing, borehole row spacing, and borehole depth, the present invention comprehensively considers factors such as the in-hole detonation wave, the action time of the inter-hole explosion stress wave, and the strength of the medium during explosive detonation, and establishes an expression for the inter-hole delay time of pre-splitting blasting, providing a basis for selecting the delay time of pre-splitting blasting in blasting areas with well-developed rock joints and fractures and complex surrounding structures; By rationally designing four drilling and blasting parameters—borehole spacing, borehole row spacing, borehole depth, and blasting delay time—the present invention can effectively improve slope stability in complex environments with well-developed joints, fractured rock masses, and surrounding buildings, saving slope protection costs and reducing the cost of concrete shotcreting; The present invention provides a system adapted to the method, which can improve the practicality of the method and facilitate its promotion.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for pre-splitting blasting of gentle slopes using a hole-by-hole approach, characterized in that, Includes the following steps: A geological survey of the blasting area was conducted to determine the comprehensive information on the engineering geological conditions of the blasting area, and then four drilling and blasting parameters were determined: borehole spacing, borehole row spacing, borehole depth, and blasting delay. Within the blasting zone, RTK line laying and measuring points are used, and the blasting hole coordinate data is obtained by combining the 3D point cloud data of the blasting zone, the blasting hole spacing, and the blasting hole row spacing. The borehole coordinate data is imported into the operation control system of the intelligent drilling rig. Based on the intelligent positioning system on the intelligent drilling rig, the borehole is located and located, and drilling is completed according to the borehole depth. Charge explosives into the boreholes and check the connection of the detonation network. Detonate the boreholes one by one in the order of pre-splitting holes, main blasting holes, and auxiliary holes. The pre-splitting holes are detonated one by one with a short delay according to the blasting delay. In the blasting area, on-site blasting was carried out to calculate the vibration reduction rate of pre-splitting blasting hole by hole, and at the same time, the half-hole rate after pre-splitting blasting hole by hole was counted and the degree of damage to the surrounding rock was judged.

2. The method for pre-splitting blasting of a gentle slope by hole as described in claim 1, characterized in that, The process of conducting a geological survey of the blasting area and determining comprehensive information on the engineering geological conditions of the blasting area, and then determining four drilling and blasting parameters—borehole spacing, borehole row spacing, borehole depth, and blasting delay—includes the following steps: A geological survey of the blasting area was conducted to determine the comprehensive information on the engineering geological conditions of the blasting area. The comprehensive information on geological conditions included mining parameters, borehole diameter, and rock mechanics parameters. The spacing between boreholes in the same row is determined based on the borehole diameter. The auxiliary holes and the main blasting holes are evenly distributed in the rock mass of the main blasting area, and the hole spacing is determined by adjusting and optimizing the hole profile design drawing. The depth of the blast hole is determined based on the mining parameters of the mining area and the trigonometric function calculation method, including the depth of the pre-splitting hole, the depth of the auxiliary hole and the depth of the main blast hole; Based on the rock mechanics parameters, and taking into account the duration of the detonation wave inside the hole, the duration of the explosion stress wave between the holes, and the strength of the medium during the explosive explosion, the blasting delay is calculated.

3. The method for pre-splitting blasting of a gentle slope by hole as described in claim 2, characterized in that, The depth of the pre-cracked hole satisfies the following relationship: Where L is the depth of the pre-splitting hole, H is the height of the blasting zone step, and h is the extra depth. The perforation angle for the pre-cracked hole.

4. The method for pre-splitting blasting of a gentle slope by hole as described in claim 2, characterized in that, The depth of the auxiliary hole satisfies the following relationship: in, The depth of the auxiliary holes in the i-th row is [the depth of the auxiliary holes]. The distance between the pre-cracked hole and the auxiliary holes in the i-th row is given. To ensure the vertical safety distance between the bottom of the auxiliary hole and the pre-cracked surface, Let i be the slope angle of the step, and i be the number of rows of auxiliary holes.

5. The method for pre-splitting blasting of a gentle slope by hole as described in claim 2, characterized in that, The depth of the main blast hole satisfies the following relationship: in, H is the depth of the main blast hole, H is the height of the blast zone step, and h is the borehole depth.

6. The method for pre-splitting blasting of a gentle slope by hole as described in claim 1, characterized in that, The blasting delay satisfies the following relationship: in, The length of the propellant charge inside the borehole. Let be the propagation speed of the detonation wave, and n be the ratio of the crack depth to its length. The spacing between pre-cracked holes, The longitudinal wave velocity of the stress wave in the rock. For the blasting delay, The radius of the borehole is... This is the critical size for crack propagation.

7. The method for pre-splitting blasting of a gentle slope by hole as described in claim 1, characterized in that, The process of entering the fractured rock mining area after blasting to inspect the size of the blasted blocks and measure the width of the pre-cracks, and to statistically analyze the half-wall porosity and calculate the vibration reduction rate includes the following steps: Simultaneous pre-splitting blasting and hole-by-hole pre-splitting blasting were carried out in the same blasting zone, and the measured vibration velocity under the two initiation methods was measured respectively, and then the vibration reduction rate of hole-by-hole pre-splitting blasting was calculated. After the pre-splitting blasting is completed, a 3D laser scanner is used to scan the slope surface to obtain images of the slope surface after blasting. Based on the original design depth of the pre-splitting holes, the reinforced, normal, and weakened charge sections and the filling section in the slope surface images are scaled down proportionally. The processed slope image is imported into CAD software, and the half-hole ratio of different charge sections is measured to obtain the half-hole ratio after pre-splitting blasting. Each pre-splitting hole is divided into three regions according to the charge section and subjected to grayscale and binarization processing. The target region is covered with square grids. The fractal dimension is calculated by counting the number of boxes covering the cross section, thereby determining the degree of damage to the surrounding rock.

8. The method for pre-splitting blasting of a gentle slope by hole as described in claim 7, characterized in that, The vibration reduction rate satisfies the following relationship: in, The vibration reduction rate is... The measured vibration velocity of the simultaneous pre-splitting blasting is given. The measured vibration velocity is the value of the pre-splitting blasting per hole.

9. The method for pre-splitting blasting of a gentle slope by hole as described in claim 7, characterized in that, The fractal dimension satisfies the following relationship: in, Let fractal dimension be denoted as . The number of boxes covering the cross-section. Let be the side length of the k-th square.

10. A pre-splitting blasting system for gentle slopes, characterized in that, The aforementioned gentle slope pre-splitting blasting system includes: a data acquisition device, a data output device, a processor, and a storage device. The storage device includes a computer-readable storage medium storing a computer program. The computer program includes program instructions, which, when executed by the processor, cause the processor to implement the gentle slope pre-splitting blasting method as described in any one of claims 1-9.

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