Precise control blasting construction method for high and steep slope of surface mine

Abstract

The invention discloses an accurate control blasting construction method for a high and steep slope of a surface mine, and relates to the field of blasting operation. The accurate control blasting construction method for the high and steep slope of the surface mine is outstanding in safety benefit, and the long-term stability of the slope is greatly improved by forming the high-quality flat slope, so that the risks of landslide and rockfall are fundamentally reduced, and the safety of personnel and equipment below is guaranteed; the economic benefit is remarkable, overexcavation and underexcavation of the side slope are reduced, the stripping amount is close to a design value, the cost is saved, a steeper slope angle can be adopted for stabilizing the side slope, the total rock stripping amount is reduced, recoverable resources are increased, and the service life of a mine is prolonged; the technical benefit is obvious, the half-hole rate is improved, the surrounding rock damage and blasting vibration are reduced, and a better foundation is provided for slope supporting operation such as follow-up anchor rod and anchor cable installation; environmental and operation benefits are improved, environmental damage caused by slope instability is reduced, drainage system arrangement and daily safety inspection are better facilitated through slope leveling, and long-term maintenance cost is reduced.

Description

Technical Field

[0001] This invention relates to blasting operation technology, specifically to a method for precise control of blasting construction on steep slopes in open-pit mines. Background Technology

[0002] The steep slopes of open-pit mines are key engineering structures formed during the production process, and their long-term stability is directly related to mine operation safety, production efficiency and economic benefits.

[0003] Traditional blasting methods generate intense vibrations and excessive fragmentation, which can severely damage the integrity of the slope rock mass, creating potential slip surfaces or weak points, thus triggering major geological disasters such as landslides and collapses. Therefore, the core objective of precise controlled blasting for steep slopes is to minimize damage to the rock mass remaining on the slope, creating a smooth, flat, and stable designed slope profile. This ensures the long-term stability of the slope from the outset and reduces subsequent maintenance costs and safety risks. Summary of the Invention

[0004] The purpose of this invention is to provide a precise controlled blasting construction method for steep slopes in open-pit mines, in order to solve the problem that existing blasting methods can seriously damage the integrity of the slope rock mass, forming potential slip surfaces or weak surfaces, thereby causing major geological disasters such as landslides and collapses.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for precise controlled blasting construction on steep slopes in open-pit mines, comprising:

[0006] Before the blasting design, a geological survey and exploration of the slope area is carried out, and a slope geological model is established based on the survey data;

[0007] Based on the preliminary survey data, an initial blasting plan was designed, and the blasting process was simulated using numerical simulation software. The parameters were adjusted and optimized based on the simulation results to determine the optimal blasting plan.

[0008] Level the site to prepare for construction, use a drilling rig to drill holes at the designed locations, clean the rock powder and water inside the holes after drilling, and drill or seal any unqualified blast holes.

[0009] According to the designed charge amount and charge structure, place the explosive and detonating cord in place. Use the specified rock chips or special stemming clay to tightly seal the top of the explosive to ensure that the designed sealing length is reached. After completion, check the uniformity of the charge and the tightness of the sealing.

[0010] According to the designed detonation sequence, high-precision delayed detonators are used to reliably connect the in-hole and inter-hole detonation networks, delineate the blasting safety warning zone, and after confirming that the warning is in place, a designated person operates the detonation equipment to detonate at the preset time.

[0011] During the blasting process, a blasting vibration monitoring instrument is used to monitor the remaining rock mass in real time and record any abnormalities. After the blasting is completed and a specified safe time has elapsed, professional personnel are organized to enter the work area for inspection and repair.

[0012] Preferably, the geological survey and exploration includes:

[0013] Lithology and structural plane investigation: The attitude of joints, fissures, and faults was determined using a geological compass, every 100m. 2 No fewer than 30 structural surface measuring points were collected within the survey area to record the fracture density and extension range; the thickness of the fault fracture zone was measured with an accuracy controlled within ±0.1m.

[0014] Rock mass mechanical parameter testing: Rock mass wave velocity was tested using an RSM-SY5 sonic transducer with a frequency range of 20–200 kHz and a testing accuracy of ±10 m / s. The longitudinal wave velocity of the rock mass is generally required to be ≥2500 m / s and 1500–2500 m / s. Rock strength was determined by uniaxial compressive strength testing using a YES-2000 pressure testing machine with a loading rate of 0.5–1.0 MPa / s. Each test group consisted of no less than 5 standard rock samples, and the average value was taken as the uniaxial compressive strength σc of the rock.

[0015] Geometric and hydrological parameters were determined: the slope height, slope, and aspect were measured using a total station; the groundwater permeability coefficient k was determined using a light wellpoint dewatering test with a test accuracy of ±0.01m / d, and the groundwater level was recorded simultaneously.

[0016] Geological model establishment: Based on the survey data, a three-dimensional geological model is constructed using Surfer or GOCAD software. The model grid resolution is no less than 0.5m×0.5m×0.5m, and the spatial intersection relationship between the structural plane and the slope is clearly defined.

[0017] Preferably, combining survey data and blasting targets, a combination of pre-splitting blasting as the primary method and smooth blasting as a secondary method is adopted, and then the blasting scheme parameters are designed and optimized. The design and optimization steps of the optimal blasting scheme are as follows:

[0018] Drilling layout design:

[0019] a. Pre-splitting hole parameters: Hole spacing a = (8~12)d, where d is the diameter of the blast hole. When d = 150mm, a = 1.2~1.8m; Hole depth H = slope step height h + 0.5~1.0m; Inclination angle is consistent with the slope surface inclination angle, with an error ≤ 0.5°;

[0020] b. Main blast hole parameters: buffer distance from pre-splitting holes b = (1.5~2.0)a, i.e. 1.8~3.6m; hole spacing a1 = (1.2~1.5)a, row spacing b1 = (0.8~1.0)a1; hole depth H1 = h + 1.0~1.5m;

[0021] Charge structure design:

[0022] a. Pre-splitting holes use decoupled charging. The decoupling coefficient Kd = dhole / dcharge, where dhole is the borehole diameter and dcharge is the charge cartridge diameter. For hard rock, Kd = 2.0–3.0; for soft rock, Kd = 1.5–2.0. The linear charge density qline is calculated using the formula: Where K is the lithology coefficient, σc is the uniaxial compressive strength of the rock, and d is the borehole diameter;

[0023] b. The main blast hole uses interval charging, with air or flexible foam as the interval material. The interval length Linterval = (0.2~0.3)H1, and the charge amount Q is calculated according to the formula: , where q is the unit explosive consumption;

[0024] Initiation timing design: MS series millisecond delay detonators are used, and the pre-splitting holes are detonated Δt=75~150ms earlier than the main detonation holes; the main detonation holes adopt row-by-row micro-delay initiation, with a row-to-row time difference Δt1=50~100ms;

[0025] Numerical simulation optimization: ANSYS / LS-DYNA software was used, the rock mass was set as an elastoplastic material, the explosive was set to the JWL equation of state, and the mesh size was 0.2m×0.2m×0.2m. The propagation of blasting stress waves was simulated. Based on the simulated peak vibration velocity and fragmentation range of the slope, the charge amount and detonation time difference were adjusted to ensure that the simulation results met the blasting target requirements.

[0026] Preferably, the drilling construction steps include:

[0027] Construction preparation: Use a PC200 excavator to clear loose rocks and debris from the slope working surface, with the clearing range extending more than 5m beyond the edge of the blasting area; use a level to level the construction site, ensuring the site flatness error is ≤5cm; debug the KQG150 down-the-hole drill, ensuring the guide system accuracy is ≤0.1°, the drilling speed is adjusted to 200~300r / min, and the advance speed is controlled at 0.5~1.0m / min;

[0028] Precision drilling: Based on the designed hole position, a total station is used for positioning, with a hole position deviation of ≤5cm; during the drilling process, the hole inclination is monitored in real time, with an inclination error of ≤1%; the hole depth is measured by the drill rod length and verified by the measuring rope, with an error of ≤10cm.

[0029] Post-drilling treatment: After drilling, use high-pressure air to clean the rock powder inside the hole, with a cleaning time of ≥5 min / hole; measure the water accumulation inside the hole, and use a submersible pump to pump out water when the water depth is >30 cm; use a ZK-1 borehole measuring instrument to check the hole diameter and hole inclination, and for blast holes with inclination exceeding the tolerance or hole diameter deviation >10 mm, use hole enlargement or additional drilling, with the distance between the additional drilling position and the original hole position ≤30 cm.

[0030] Preferably, the loading step includes:

[0031] Precision charging: Manual charging is performed using a ZY-1 type charging device. When charging pre-splitting holes, the explosive cartridges are tied to the detonating cord and lowered at a uniform speed, with a cartridge spacing of ≤50cm, ensuring that the linear charge density deviation is ≤±5%. When charging main blasting holes at intervals, the position of the explosive section is fixed with a locator, and the distance error between the upper and lower explosive sections is ≤10cm. The charge amount is controlled according to the calculated value of formula Q, with a deviation of ≤±3%.

[0032] Standardized plugging: The plugging material should be dry rock cuttings or special stemming clay. The plugging length L is calculated using the formula: Q is the charge amount per borehole, d is the borehole diameter, and L_plug ≥ 1.5m; during plugging, layered compaction is adopted, with each layer having a thickness of 20cm and a compaction pressure ≥ 0.3MPa, ensuring a plugging density ≥ 90%;

[0033] Quality inspection: After loading the explosives, measure the position of the explosive pack with a measuring rope, and the deviation should be ≤10cm; use an ultrasonic density tester to test the density of the plugging. For boreholes with a density of <90%, add plugging material and re-tamp.

[0034] Preferably, the detonation network connection adopts a detonating cord + millisecond delay detonator dual network. MS1 segment detonators are used for pre-splitting holes, and MS3 to MS10 segment detonators are used for main detonation holes. The detonator segment error is ≤5ms. When connecting, the overlap length of the detonating cord is ≥15cm, the overlap angle is ≥90°, and it is tightly wrapped with tape. The number of detonators in series in each detonation branch is ≤20, and the branches are connected in parallel. The total network resistance deviation is ≤±5Ω. The test is repeated 3 times to ensure that there are no short circuits or open circuits.

[0035] Safety Protection: a. Calculation of Warning Range: According to the formula Determine that Qmax is the maximum amount of explosive charge in one stage, and R is the warning radius. When Q... max When the weight is 100kg, R = 20 × ∛100 ≈ 73m. The actual warning range is expanded by 20%, so we take 88m. b. Protective measures: Erect a double-layer protective net above the slope of the blasting area. The height of the protective net is ≥ 3m. Protective sheds are used to shield the equipment around the blasting area. The thickness of the protective sheds is ≥ 5cm.

[0036] Detonation preparation: Conduct safety and technical briefings for the workers and clarify the detonation signal; organize at least 3 guards to stand guard at the entrances and exits of the warning area, use walkie-talkies to communicate in real time, and after confirming that all irrelevant personnel and equipment have been evacuated, a designated person operates the detonator and detonates at the preset time.

[0037] Preferably, during the blasting process:

[0038] Blasting process monitoring: A TC-4850 blasting vibration monitoring instrument was used to set up monitoring points at 5m, 10m and 20m away from the blasting area on the retained slope to record the peak vibration velocity (V) and the dominant frequency (f) in real time; at the same time, a sound level meter was used to monitor the air shock wave noise and control the noise to ≤120dB.

[0039] Post-explosion inspection: After the blasting is completed, wait 15-30 minutes to ensure air quality (dust concentration ≤10mg / m³). 3 After the vibration intensity returns to a safe range, organize professional personnel to enter the work area and inspect the following:

[0040] a. Slope flatness: Use a 2m straightedge to check, gap ≤10cm, over-excavation ≤10cm, under-excavation ≤5cm;

[0041] b. Half-hole ratio: Randomly select 10 pre-cracked hole locations, count the number of half-holes, and the half-hole ratio is ≥85%;

[0042] c. Stability: The width of new cracks is detected using a crack width meter. If the crack width is >2mm, monitoring points need to be set up for tracking and observation.

[0043] d. Misfire handling: Misfires should be handled by "water flushing + reloading". Direct detonation is strictly prohibited.

[0044] Slope trimming: Over-excavated areas are removed using pneumatic picks, and under-excavated areas are trimmed using shallow-hole blasting; loose rocks and dangerous rocks are cleared using excavators, with the clearing area extending 3m beyond the edge of the slope to ensure that there is no loose rock mass on the slope surface.

[0045] Compared with existing technologies, the present invention provides a precise controlled blasting construction method for steep open-pit mine slopes, which offers outstanding safety benefits. By forming a high-quality, flat slope, it greatly improves the long-term stability of the slope, fundamentally reducing the risk of landslides and rockfalls, and ensuring the safety of personnel and equipment below. It also offers significant economic benefits, reducing over-excavation and under-excavation, bringing the stripping amount closer to the design value and saving costs. Furthermore, it allows for steeper slope angles to be used to stabilize the slope, reducing the total amount of stripped rock, increasing recoverable resources, and extending the mine's service life. Technically, it increases the half-hole ratio, reduces damage to the surrounding rock and blasting vibration, and provides a better foundation for subsequent slope support operations such as anchor bolt and cable installation. Finally, it improves environmental and operational benefits, reducing environmental damage caused by slope instability, and the flat slope surface facilitates drainage system layout and daily safety inspections, reducing long-term maintenance costs. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0047] Figure 1 A flowchart illustrating the method for precise control of blasting on steep slopes in open-pit mines, provided in an embodiment of the present invention. Detailed Implementation

[0048] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0049] As attached Figure 1 As shown:

[0050] Example:

[0051] This invention provides a method for precise controlled blasting construction on steep slopes in open-pit mines, comprising:

[0052] Before the blasting design, a geological survey and exploration of the slope area is carried out, and a slope geological model is established based on the survey data;

[0053] Based on the preliminary survey data, an initial blasting plan was designed, and the blasting process was simulated using numerical simulation software. The parameters were adjusted and optimized based on the simulation results to determine the optimal blasting plan.

[0054] Level the site to prepare for construction, use a drilling rig to drill holes at the designed locations, clean the rock powder and water inside the holes after drilling, and drill or seal any unqualified blast holes.

[0055] According to the designed charge amount and charge structure, place the explosive and detonating cord in place. Use the specified rock chips or special stemming clay to tightly seal the top of the explosive to ensure that the designed sealing length is reached. After completion, check the uniformity of the charge and the tightness of the sealing.

[0056] According to the designed detonation sequence, high-precision delayed detonators are used to reliably connect the in-hole and inter-hole detonation networks, delineate the blasting safety warning zone, and after confirming that the warning is in place, a designated person operates the detonation equipment to detonate at the preset time.

[0057] During the blasting process, a blasting vibration monitoring instrument is used to monitor the remaining rock mass in real time and record any abnormalities. After the blasting is completed and a specified safe time has elapsed, professional personnel are organized to enter the work area for inspection and repair.

[0058] As can be seen from the above, this method has outstanding safety benefits. By forming a high-quality, flat slope, it greatly improves the long-term stability of the slope, fundamentally reducing the risk of landslides and rockfalls, and ensuring the safety of personnel and equipment below. It also has significant economic benefits, reducing over-excavation and under-excavation of the slope, bringing the stripping amount close to the design value and saving costs. Furthermore, the stabilized slope can use a steeper slope angle, reducing the total amount of stripped rock, increasing recoverable resources, and extending the service life of the mine. It also has significant technical benefits, increasing the half-hole ratio, reducing damage to the surrounding rock and blasting vibration, and providing a better foundation for subsequent slope support operations such as anchor bolt and anchor cable installation. Finally, it improves environmental and operational benefits, reducing environmental damage caused by slope instability, and the flat slope surface is more conducive to the layout of drainage systems and daily safety inspections, reducing long-term maintenance costs.

[0059] The geological survey and exploration includes:

[0060] Lithology and structural plane investigation: The attitude (strike, dip, and dip angle) of joints, fissures, and faults was determined using a geological compass, every 100m. 2 There should be no fewer than 30 structural surface measuring points within the survey area. Record the fracture density (number of fractures per unit length, generally with a survey accuracy of 0.1 fractures / m) and the extent of fracture (error ≤ 0.5m). The thickness of the fault fracture zone should be measured, with an accuracy controlled within ±0.1m.

[0061] Rock mass mechanical parameter testing: Rock mass wave velocity was tested using an RSM-SY5 sonic transducer with a frequency range of 20–200 kHz and a testing accuracy of ±10 m / s. The longitudinal wave velocity of the rock mass is generally required to be ≥2500 m / s (hard rock) and 1500–2500 m / s (soft rock). Rock strength was determined by uniaxial compressive strength testing using a YES-2000 pressure testing machine with a loading rate of 0.5–1.0 MPa / s. Each test group consisted of no less than 5 standard rock samples (φ50 mm × 100 mm), and the average value was taken as the uniaxial compressive strength σc (unit: MPa).

[0062] Geometric and hydrological parameters were determined as follows: a total station (angle accuracy ±2″, distance accuracy ±(2mm+2ppm×D)) was used to measure the slope height (error ≤0.2m), slope (error ≤0.5°), and aspect; a light wellpoint dewatering test was used to determine the groundwater permeability coefficient k (unit: m / d), with a test accuracy of ±0.01m / d, and the groundwater level elevation was recorded simultaneously (error ≤0.1m).

[0063] Geological model establishment: Based on the survey data, a three-dimensional geological model is constructed using Surfer or GOCAD software. The model grid resolution is no less than 0.5m×0.5m×0.5m, and the spatial intersection relationship between the structural plane and the slope is clearly defined.

[0064] Quantitative surveys yield precise data, providing a quantitative basis for subsequent parameter design. For example, rock mass wave velocity can be used to determine rock mass integrity (integrity coefficient Kv = (rock mass P-wave velocity / rock P-wave velocity)², Kv ≥ 0.75 indicates intact rock mass, 0.5–0.75 indicates relatively intact rock mass), and the integrity coefficient directly affects the adjustment of explosive charge. Structural plane orientation data can determine the optimal direction of the blasting free face (preferably selecting a direction with an angle of 30°–60° to the strike of the structural plane as the free face to improve blasting efficiency). Groundwater permeability coefficient determines whether pre-dewatering is necessary (when k ≥ 0.1 m / d, pre-dewatering to 0.5 m below the bottom of the borehole is required) to avoid groundwater affecting explosive performance. Accurate geological models can predict blasting weak areas in advance, optimize borehole layout accordingly, and reduce the risk of slope instability after blasting.

[0065] Based on the survey data and blasting targets (slope flatness error ≤10cm, half-hole ratio ≥85%, blasting vibration velocity ≤15cm / s), a combination of pre-splitting blasting as the main method and smooth blasting as the auxiliary method is adopted. The blasting scheme parameters are then designed and optimized. The design and optimization steps for the optimal blasting scheme are as follows:

[0066] Drilling layout design:

[0067] a. Pre-splitting hole parameters: Hole spacing a = (8~12)d, where d is the diameter of the blast hole. When d = 150mm, a = 1.2~1.8m; Hole depth H = slope step height h + 0.5~1.0m (e.g., when h = 15m, H = 15.5~16m); The dip angle is consistent with the slope surface dip angle, with an error ≤ 0.5°;

[0068] b. Main blast hole parameters: buffer distance from pre-splitting holes b = (1.5~2.0)a, i.e. 1.8~3.6m; hole spacing a1 = (1.2~1.5)a, row spacing b1 = (0.8~1.0)a1; hole depth H1 = h + 1.0~1.5m;

[0069] Charge structure design:

[0070] a. Pre-splitting holes use decoupled charging. The decoupling coefficient Kd = dhole / dcharge, where dhole is the borehole diameter and dcharge is the charge cartridge diameter. For hard rock, Kd = 2.0–3.0; for soft rock, Kd = 1.5–2.0. The linear charge density qline is calculated using the formula: Where K is the lithology coefficient (K=0.008~0.012 for granite, K=0.006~0.009 for sandstone, and K=0.004~0.006 for shale), σc is the uniaxial compressive strength of the rock, and d is the borehole diameter. The calculation result is in kg / m. For example, when σc=80MPa, d=0.15m, and K=0.01, q_line=0.01×√80×0.15≈0.013kg / m;

[0071] b. The main blast hole uses interval charging, with air or flexible foam as the interval material. The interval length Linterval = (0.2~0.3)H1, and the charge amount Q is calculated according to the formula: Where q is the unit explosive consumption (kg / m³, q=0.4~0.6 for hard rock, q=0.2~0.4 for soft rock).

[0072] Initiation sequence design: MS series millisecond delay detonators are used. The pre-splitting holes are initiated Δt = 75~150ms earlier than the main blasting holes (adjusted according to the integrity of the rock mass, with the larger value taken for intact rock mass); the main blasting holes are initiated row by row with micro-delay initiation, and the time difference between rows is Δt1 = 50~100ms.

[0073] Numerical simulation optimization: ANSYS / LS-DYNA software was used, with the rock mass set as an elastoplastic material, the explosive as a JWL equation of state, and the mesh size as 0.2m×0.2m×0.2m. The propagation of blasting stress waves was simulated (the propagation velocity was taken as 0.8 times the longitudinal wave velocity of the rock mass). Based on the simulated peak vibration velocity and fracture range of the slope, the charge amount and initiation time difference were adjusted to ensure that the simulation results met the blasting target requirements.

[0074] Quantitative parameter design and simulation optimization are the core of achieving precise blasting. Precise control of pre-splitting hole spacing and decoupling coefficients ensures smooth pre-crack penetration (crack width controlled within 2-5mm), effectively blocking the main blast stress wave (stress attenuation rate ≥60%). The application of the linear charge density formula avoids overloading or underloading caused by empirical values. Overloading will lead to excessive fragmentation of the slope rock mass (fracture range increased by more than 30%), while underloading will prevent the formation of effective pre-cracks. The main blast hole charge formula can precisely control blasting energy, and combined with micro-delay initiation timing, reduces blasting vibration velocity by 40%-60%, avoiding resonance damage to the preserved rock mass. Numerical simulation can identify parameter design defects in advance (such as stress concentration areas), and by optimizing parameters, the blasting effect compliance rate can be increased to over 90%, reducing field test costs.

[0075] The drilling construction steps include:

[0076] Construction preparation: Use a PC200 excavator to clear loose rocks and debris from the slope working surface, with the clearing range extending more than 5m beyond the edge of the blasting area; use a level to level the construction site, ensuring the site flatness error is ≤5cm; debug the KQG150 down-the-hole drill (equipped with GPS + tilt sensor guidance system), ensuring the guidance system accuracy is ≤0.1°, adjust the drilling speed to 200~300r / min, and control the advance speed to 0.5~1.0m / min;

[0077] Precision drilling: Based on the designed hole position, a total station is used for positioning, with a hole position deviation of ≤5cm; during the drilling process, the hole inclination is monitored in real time (monitored once every 2m of drilling), with a hole inclination error of ≤1% (i.e., when the hole depth is 15m, the hole bottom deviation is ≤15cm); the hole depth is measured by the drill rod length and verified by the measuring rope, with an error of ≤10cm.

[0078] Post-drilling treatment: After drilling, use high-pressure air (pressure ≥ 0.6 MPa) to clean the rock powder inside the hole, with a cleaning time ≥ 5 min / hole; measure the water accumulation inside the hole, and use a submersible pump to pump out water when the water depth is > 30 cm; use a ZK-1 borehole measuring instrument (measurement accuracy ± 2 mm) to check the hole diameter and hole inclination. For boreholes with inclination exceeding the tolerance (> 1%) or hole diameter deviation > 10 mm, use hole enlargement or additional drilling. The distance between the additional drilling position and the original hole position should be ≤ 30 cm.

[0079] High-precision drilling control is crucial for ensuring the successful implementation of design parameters. A hole position deviation of ≤5cm ensures precise placement of pre-splitting holes along the designed slope line, preventing "sawtooth" slopes. A hole inclination error of ≤1% guarantees all pre-splitting holes are on the same design plane, ensuring continuous pre-splitting. Excessive inclination leads to pre-splitting misalignment (misalignment >10cm), creating a "patched-on" defect and reducing stress wave blocking effectiveness by more than 50%. Hole depth error control prevents "under-drilling" or "over-drilling." Under-drilling results in residual rock embankments on the slope (height >20cm), affecting subsequent operational safety. Over-drilling increases explosive consumption (0.5-1.0kg more explosive for every 1m of excess depth). Precise detection by a borehole measuring instrument can control the rate of defective holes below 5%, significantly improving the stability of blasting results.

[0080] The loading step includes:

[0081] Precision charging: Charging is performed manually with a ZY-1 type charging device. When charging pre-splitting holes, the explosive cartridges (φ32mm or φ45mm in diameter) are tied to the detonating cord (detonation velocity ≥6500m / s) and lowered at a uniform speed, with a cartridge spacing ≤50cm, ensuring the linear charge density deviation is ≤±5% (checked against the design q line). When charging main blasting holes at intervals, the position of the explosive section is fixed with a locator, the distance error between upper and lower explosive sections is ≤10cm, and the charge amount is controlled according to the calculated value of formula Q, with a deviation ≤±3%.

[0082] Standardized plugging: The plugging material should be dry rock chips (particle size 5-20mm) or special stemming clay (compressive strength ≥0.5MPa). The plugging length L is calculated using the formula: Q is the charge amount per borehole, d is the borehole diameter, and L_plug ≥ 1.5m; during plugging, layered compaction is adopted, with each layer having a thickness of 20cm and a compaction pressure ≥ 0.3MPa, ensuring a plugging density ≥ 90%;

[0083] Quality inspection: After loading the explosives, measure the position of the explosive pack with a measuring rope, and the deviation should be ≤10cm; use an ultrasonic density tester to test the density of the plugging. For boreholes with a density of <90%, add plugging material and re-tamp.

[0084] Precise charging ensures that blasting energy is distributed according to design. A linear charge density deviation of ≤±5% guarantees uniform penetration of pre-cracks. Local overcharging (deviation >5%) leads to excessive fracturing of the borehole wall rock (fracturing range expands by more than 20cm), resulting in over-excavation. Local undercharging causes pre-cracks to fail to penetrate, losing their stress wave blocking effect. The application of the plugging length formula ensures that detonation gases act fully on the borehole wall, preventing premature escape. When the plugging length is insufficient, the detonation gas escape rate accelerates, the explosive energy utilization rate decreases by more than 40%, and the flyrock distance increases by 2 to 3 times. Layered compaction ensures a density of ≥90%, which can further improve energy utilization, reduce the intensity of air shock waves (shock wave peak pressure decreases by 30% to 50%), effectively control the flyrock range (controlled within 50m), and ensure construction safety.

[0085] The detonation network connection adopts a detonating cord + millisecond delay detonator dual network. MS1 detonators (delay time 0ms) are used for pre-splitting holes, and MS3 to MS10 detonators (delay time 50 to 1000ms) are used for main detonation holes. The detonator segment error is ≤5ms. When connecting, the overlap length of the detonating cord is ≥15cm, the overlap angle is ≥90°, and it is tightly wrapped with tape (wrapping ≥5 turns). The number of detonators in series in each detonation branch is ≤20, and the branches are connected in parallel. The total resistance deviation of the network is ≤±5Ω (tested with a DM-500 resistance tester). The test is repeated 3 times to ensure no short circuit or open circuit.

[0086] Safety Protection: a. Calculation of Warning Range: According to the formula Determine that Qmax is the maximum amount of explosive charge in one stage, and R is the warning radius. When Q... max =100kg, R=20×∛100≈73m, the actual warning range is expanded by 20%, and taken as 88m; b. Protective measures: erect a double-layer protective net above the slope of the blasting area (the first layer is a steel mesh, with a mesh size of 10cm×10cm; the second layer is a nylon mesh with a tensile strength ≥5kN / m), and the height of the protective net is ≥3m; protective sheds are used to shield the equipment around the blasting area, and the thickness of the protective sheds is ≥5cm (wooden boards + rubber mats).

[0087] Detonation preparation: Conduct safety and technical briefings for the personnel, clarifying the detonation signals (warning signal: 3 whistles, 10s each; detonation signal: 1 whistle, 20s; all-clear signal: 2 whistles, 10s each); organize at least 3 guards to stand guard at the entrances and exits of the warning area, communicate in real time using walkie-talkies, and after confirming that all irrelevant personnel and equipment have been evacuated, a designated person operates the detonator (detonation voltage ≥24V) and detonates according to the preset time.

[0088] The precise resistance control of the dual-detonation network (deviation ≤ ±5Ω) ensures accurate detonation of detonators according to the designed sequence (timing error ≤ 5ms). The pre-splitting holes detonate first to form complete pre-cracks before the main detonation holes detonate, effectively isolating stress waves. If the timing is disordered, the stress wave from the main detonation will directly act on the remaining rock mass before the pre-cracks form, causing the slope vibration velocity to exceed the standard (>15cm / s), leading to new cracks in the rock mass. The application of the warning range formula can scientifically delineate dangerous areas, preventing injuries from flying rocks and shock waves. The double-layer protective net can increase the flying rock interception rate to over 95%, and the protective canopy can effectively reduce shock wave damage to equipment (equipment damage rate reduced by 60%). Standardized detonation signals and communication guarantees can prevent accidental detonation accidents, ensuring safe and orderly construction.

[0089] During the blasting process:

[0090] Blasting process monitoring: A TC-4850 blasting vibration monitor (measuring range 0.01~30cm / s, frequency range 5~500Hz, accuracy ±1%) was used. Monitoring points were set up at 5m, 10m and 20m away from the blasting area on the retained slope to record the peak vibration velocity (V) and the dominant frequency (f) in real time. At the same time, a sound level meter (measuring range 30~140dB, accuracy ±1dB) was used to monitor the air shock wave noise and control the noise to ≤120dB.

[0091] Post-explosion inspection: After the blasting is completed, wait 15-30 minutes (adjust according to the type of explosive; 15 minutes for emulsion explosives and 30 minutes for nitrous oxide explosives) to ensure air quality (dust concentration ≤ 10 mg / m³). 3 After the vibration intensity returns to a safe range, organize professional personnel to enter the work area and inspect the following:

[0092] a. Slope flatness: Use a 2m straightedge to check, gap ≤10cm, over-excavation ≤10cm, under-excavation ≤5cm;

[0093] b. Half-hole ratio: Randomly select 10 pre-cracked hole locations, count the number of half-holes, and the half-hole ratio is ≥85%;

[0094] c. Stability: The width of new cracks is detected using a crack width meter (measuring range 0-5mm, accuracy ±0.01mm). If the crack width is >2mm, monitoring points need to be set up for tracking and observation.

[0095] d. Misfire handling: Misfires should be handled by "water flushing + reloading". Direct detonation is strictly prohibited.

[0096] Slope trimming: Over-excavated areas are removed using pneumatic picks (trimming depth ≤ 20cm), and under-excavated areas are trimmed using shallow-hole blasting (single hole charge ≤ 0.5kg); loose rocks and dangerous rocks are cleared using excavators, with the clearing range extending 3m beyond the slope edge to ensure that there are no loose rocks on the slope surface (loose rocks weighing > 50kg need to be manually pried off).

[0097] Blasting vibration monitoring data (V, f) can quantitatively assess the impact on the retained rock mass. If V > 15 cm / s or f is close to the natural frequency of the rock mass (generally 5–20 Hz), subsequent blasting parameters need to be adjusted (such as reducing the single-stage charge amount and increasing the initiation time difference) to avoid resonance damage. Noise and dust monitoring can ensure compliance with requirements and protect the health of workers. Post-blast flatness and half-hole ratio checks are core indicators for verifying blasting effectiveness. A half-hole ratio ≥ 85% indicates that the pre-splitting effect is up to standard, and the slope stability is improved by more than 70%. Crack width detection can promptly identify potential instability hazards, and tracking observation data (recorded once every 2 hours for 24 hours) can determine whether cracks are developing, avoiding landslide accidents. Slope trimming can ensure that the slope surface flatness meets the standard. After removing loose rock mass, the overall stability of the slope is further improved, providing a flat foundation for subsequent anchor bolt support (if necessary), while reducing later maintenance costs (maintenance costs are reduced by 40%–60%).

[0098] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for precise controlled blasting construction on steep slopes in open-pit mines, characterized in that, include: Before the blasting design, a geological survey and exploration of the slope area is carried out, and a slope geological model is established based on the survey data; Based on the preliminary survey data, an initial blasting plan was designed, and the blasting process was simulated using numerical simulation software. The parameters were adjusted and optimized based on the simulation results to determine the optimal blasting plan. Level the site to prepare for construction, use a drilling rig to drill holes at the designed locations, clean the rock powder and water inside the holes after drilling, and drill or seal any unqualified blast holes. According to the designed charge amount and charge structure, place the explosive and detonating cord in place. Use the specified rock chips or special stemming clay to tightly seal the top of the explosive to ensure that the designed sealing length is reached. After completion, check the uniformity of the charge and the tightness of the sealing. According to the designed detonation sequence, high-precision delay detonators are used to reliably connect the in-hole and inter-hole detonation networks, delineate the blasting safety warning zone, and after confirming that the warning is in place, operate the detonation equipment to detonate at the preset time. During the blasting process, a blasting vibration monitoring instrument is used to monitor the remaining rock mass in real time and record any abnormalities. After the blasting is completed and a specified safe time has elapsed, professional personnel are organized to enter the work area for inspection and repair.

2. The method for precise controlled blasting construction on steep slopes in open-pit mines according to claim 1, characterized in that, The geological survey and exploration includes: Lithology and structural plane investigation: The attitude of joints, fissures, and faults was determined using a geological compass, every 100m. 2 No fewer than 30 structural surface measuring points were collected within the survey area to record the fracture density and extension range; the thickness of the fault fracture zone was measured with an accuracy controlled within ±0.1m. Rock mass mechanical parameter testing: Rock mass wave velocity was tested using an RSM-SY5 sonic transducer with a frequency range of 20–200 kHz and a testing accuracy of ±10 m / s. The longitudinal wave velocity of the rock mass is generally required to be ≥2500 m / s and 1500–2500 m / s. Rock strength was determined by uniaxial compressive strength testing using a YES-2000 pressure testing machine with a loading rate of 0.5–1.0 MPa / s. Each test group consisted of no less than 5 standard rock samples, and the average value was taken as the uniaxial compressive strength σc of the rock. Geometric and hydrological parameters were determined: the slope height, slope, and aspect were measured using a total station; the groundwater permeability coefficient k was determined using a light wellpoint dewatering test with a test accuracy of ±0.01m / d, and the groundwater level was recorded simultaneously. Geological model establishment: Based on the survey data, a three-dimensional geological model is constructed using Surfer or GOCAD software. The model grid resolution is no less than 0.5m×0.5m×0.5m, and the spatial intersection relationship between the structural plane and the slope is clearly defined.

3. The method for precise controlled blasting construction on steep slopes in open-pit mines according to claim 1, characterized in that, Based on the survey data and blasting target, a combination of pre-splitting blasting as the main method and smooth blasting as a supplementary method is adopted. The blasting scheme parameters are then designed and optimized. The design and optimization steps for the optimal blasting scheme are as follows: Drilling layout design: a. Pre-splitting hole parameters: Hole spacing a = (8~12)d, where d is the diameter of the blast hole. When d = 150mm, a = 1.2~1.8m; Hole depth H = slope step height h + 0.5~1.0m; Inclination angle is consistent with the slope surface inclination angle, with an error ≤ 0.5°; b. Main blast hole parameters: buffer distance from pre-splitting holes b = (1.5~2.0)a, i.e. 1.8~3.6m; hole spacing a1 = (1.2~1.5)a, row spacing b1 = (0.8~1.0)a1; hole depth H1 = h + 1.0~1.5m; Charge structure design: a. Pre-splitting holes use decoupled charging. The decoupling coefficient Kd = dhole / dcharge, where dhole is the borehole diameter and dcharge is the charge cartridge diameter. For hard rock, Kd = 2.0–3.0; for soft rock, Kd = 1.5–2.

0. The linear charge density qline is calculated using the formula: Where K is the lithology coefficient, σc is the uniaxial compressive strength of the rock, and d is the borehole diameter; b. The main blast hole uses interval charging, with air or flexible foam as the interval material. The interval length Linterval = (0.2~0.3)H1, and the charge amount Q is calculated according to the formula: , where q is the unit explosive consumption; Initiation timing design: MS series millisecond delay detonators are used, and the pre-splitting holes are detonated Δt=75~150ms earlier than the main detonation holes; the main detonation holes adopt row-by-row micro-delay initiation, with a row-to-row time difference Δt1=50~100ms; Numerical simulation optimization: ANSYS / LS-DYNA software was used, the rock mass was set as an elastoplastic material, the explosive was set to the JWL equation of state, and the mesh size was 0.2m×0.2m×0.2m. The propagation of blasting stress waves was simulated. Based on the simulated peak vibration velocity and fragmentation range of the slope, the charge amount and detonation time difference were adjusted to ensure that the simulation results met the blasting target requirements.

4. The method for precise controlled blasting construction on steep slopes in open-pit mines according to claim 1, characterized in that, The drilling construction steps include: Construction preparation: Use a PC200 excavator to clear loose rocks and debris from the slope working surface, with the clearing range extending more than 5m beyond the edge of the blasting area; use a level to level the construction site, ensuring the site flatness error is ≤5cm; debug the KQG150 down-the-hole drill, ensuring the guide system accuracy is ≤0.1°, the drilling speed is adjusted to 200~300r / min, and the advance speed is controlled at 0.5~1.0m / min; Precision drilling: Based on the designed hole position, a total station is used for positioning, with a hole position deviation of ≤5cm; during the drilling process, the hole inclination is monitored in real time, with an inclination error of ≤1%; the hole depth is measured by the drill rod length and verified by the measuring rope, with an error of ≤10cm. Post-drilling treatment: After drilling, use high-pressure air to clean the rock powder inside the hole, with a cleaning time of ≥5 min / hole; measure the water accumulation inside the hole, and use a submersible pump to pump out water when the water depth is >30 cm; use a ZK-1 borehole measuring instrument to check the hole diameter and hole inclination, and for blast holes with inclination exceeding the tolerance or hole diameter deviation >10 mm, use hole enlargement or additional drilling, with the distance between the additional drilling position and the original hole position ≤30 cm.

5. The method for precise controlled blasting construction on steep slopes in open-pit mines according to claim 1, characterized in that, The loading step includes: Precision charging: Manual charging is performed using a ZY-1 type charging device. When charging pre-splitting holes, the explosive cartridges are tied to the detonating cord and lowered at a uniform speed, with a cartridge spacing of ≤50cm, ensuring that the linear charge density deviation is ≤±5%. When charging main blasting holes at intervals, the position of the explosive section is fixed with a locator, and the distance error between the upper and lower explosive sections is ≤10cm. The charge amount is controlled according to the calculated value of formula Q, with a deviation of ≤±3%. Standardized plugging: The plugging material should be dry rock cuttings or special stemming clay. The plugging length L is calculated using the formula: Q is the charge amount per borehole, d is the borehole diameter, and L_plug ≥ 1.5m; during plugging, layered compaction is adopted, with each layer having a thickness of 20cm and a compaction pressure ≥ 0.3MPa, ensuring a plugging density ≥ 90%; Quality inspection: After loading the explosives, measure the position of the explosive pack with a measuring rope, and the deviation should be ≤10cm; use an ultrasonic density tester to test the density of the plugging. For boreholes with a density of <90%, add plugging material and re-tamp.

6. The method for precise controlled blasting construction on steep slopes in open-pit mines according to claim 1, characterized in that: The detonation network connection adopts a detonating cord + millisecond delay detonator dual network. MS1 detonators are used for pre-splitting holes, and MS3 to MS10 detonators are used for main detonation holes. The detonator segment error is ≤5ms. When connecting, the overlap length of the detonating cord is ≥15cm, the overlap angle is ≥90°, and it is tightly wrapped with tape. The number of detonators in series in each detonation branch is ≤20. The branches are connected in parallel. The total resistance deviation of the network is ≤±5Ω. It is repeatedly tested 3 times to ensure that there are no short circuits or open circuits. Safety Protection: a. Calculation of Warning Range: According to the formula Determine that Qmax is the maximum amount of explosive charge in one stage, and R is the warning radius. When Q... max When the weight is 100kg, R = 20 × ∛100 ≈ 73m. The actual warning range is expanded by 20%, so we take 88m. b. Protective measures: Erect a double-layer protective net above the slope of the blasting area. The height of the protective net is ≥ 3m. Protective sheds are used to shield the equipment around the blasting area. The thickness of the protective sheds is ≥ 5cm. Detonation preparation: Conduct safety and technical briefings for the workers and clarify the detonation signal; organize at least 3 guards to stand guard at the entrances and exits of the warning area, use walkie-talkies to communicate in real time, and after confirming that all irrelevant personnel and equipment have been evacuated, a designated person operates the detonator and detonates at the preset time.

7. The method for precise controlled blasting construction on steep slopes in open-pit mines according to claim 1, characterized in that, During the blasting process: Blasting process monitoring: A TC-4850 blasting vibration monitoring instrument was used to set up monitoring points at 5m, 10m and 20m away from the blasting area on the retained slope to record the peak vibration velocity V and the main frequency f in real time; at the same time, a sound level meter was used to monitor the air shock wave noise and control the noise to ≤120dB. Post-blast inspection: After the blasting is completed, wait 15-30 minutes to ensure that air quality and vibration intensity have returned to safe levels before organizing professional personnel to enter the work area. The inspection includes: a. Slope flatness: Use a 2m straightedge to check, gap ≤10cm, over-excavation ≤10cm, under-excavation ≤5cm; b. Half-hole ratio: Randomly select 10 pre-cracked hole locations, count the number of half-holes, and the half-hole ratio is ≥85%; c. Stability: The width of new cracks is detected using a crack width meter. If the crack width is >2mm, monitoring points need to be set up for tracking and observation. d. Misfire handling: Misfires should be handled by "water flushing + reloading". Direct detonation is strictly prohibited. Slope trimming: Over-excavated areas are removed using pneumatic picks, and under-excavated areas are trimmed using shallow-hole blasting; loose rocks and dangerous rocks are cleared using excavators, with the clearing area extending 3m beyond the edge of the slope to ensure that there is no loose rock mass on the slope surface.

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