A method for determining the amount of a booster for composite blasting perforating in a coal mine

Abstract

The application provides a coal mine composite blasting perforating booster dosage determination method, and relates to the technical field of rock mass blasting construction, and comprises the following steps: determining basic parameters of rock mass in a target blasting area and fracture energy requirement; determining initial energy of a metal jet formed by a perforating bomb; determining release energy and conversion efficiency of a unit mass of a booster, and determining minimum dosage of the booster according to the fracture energy requirement, the initial energy of the metal jet, the release energy and the conversion efficiency; determining an initial stress amplitude of the booster according to the minimum dosage, and judging whether the initial stress amplitude meets the critical stress requirement of rock mass fracture; constructing a final booster dosage calculation model to determine the final booster dosage; the application effectively improves blasting precision, reduces explosive consumption, reduces surrounding rock disturbance, and enhances roof control effect, and has wide application value in the field of mine safety production and rock stratum control.

Description

Technical Field

[0001] This invention relates to the field of rock blasting construction technology, and more specifically to a method for determining the dosage of perforation booster in coal mine composite blasting. Background Technology

[0002] Traditional roof control methods, such as hydraulic fracturing, conventional blasting pre-splitting, and mechanical cutting, suffer from problems such as uncontrollable crack direction, low blasting energy utilization, and large disturbance to the surrounding rock when dealing with high-strength rock strata. These issues can easily lead to random roof fractures or excessive residual stress, affecting the stability of the mining area and the safety of the support structure. In recent years, composite blasting directional fracture technology has been applied. This technology uses shaped charge jets to create directional cracks in the rock mass and further expands the cracks with propellants, causing the roof to collapse along a predetermined trajectory.

[0003] Currently, the main challenges in calculating propellant dosage include low accuracy in determining rock mass mechanical parameters, failure to consider the effects of joints and porosity in energy demand models, and ineffective modeling of stress wave propagation attenuation. These issues make it difficult to accurately match the propellant charge to the rock mass fracturing requirements. Overcharging may cause over-fracture of the surrounding rock, increasing the difficulty of coal mine support and even inducing roof collapse, while undercharging may lead to discontinuous fractures, making it difficult for the roof to collapse in the predetermined direction, thus affecting the effectiveness of mine pressure control. However, existing methods for determining propellant dosage mainly rely on empirical formulas or experimental data regression, failing to fully consider the heterogeneity of the rock mass, the laws of stress wave propagation, and the transmission effect of explosive energy in complex media. This makes it difficult to guarantee the accuracy of the cutting, and the blasting effect is easily affected by field conditions.

[0004] Therefore, there is an urgent need for a method to determine the dosage of propellant for composite blasting perforation in coal mines. Summary of the Invention

[0005] In view of this, the present invention provides a method for determining the amount of propellant used in perforation in coal mine composite blasting. First, the basic mechanical parameters of the rock mass within the target blasting area are measured and determined. Then, the initial energy of the metal jet formed by the perforating projectile, the energy requirement for rock mass fracturing, and the propellant energy replenishment model are defined sequentially to determine the minimum amount of propellant required. Finally, the final amount of propellant is defined by combining the initial stress amplitude after propellant replenishment. This method effectively improves blasting accuracy, reduces explosive consumption, reduces surrounding rock disturbance, and enhances roof control. It has wide application value in the fields of mine safety production and rock strata control.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for determining the dosage of a composite blasting perforation booster in coal mines includes the following steps:

[0008] S1: Determine the basic parameters of the rock mass within the target blasting area. The specific process includes:

[0009] Construct a sensor monitoring network and use the sensor monitoring network to transmit controllable sound waves or microseismic waves to the rock mass within the target blasting area;

[0010] By monitoring the propagation characteristics of controlled acoustic waves or microseismic waves within the rock mass, the basic parameters of the rock mass are determined using the acoustic inversion method. These basic parameters include: rock mass density, longitudinal wave propagation velocity, Poisson's ratio, dynamic elastic modulus, porosity, joint density, and compressive strength.

[0011] S2: Determine the initial energy of the metal jet formed by the perforating projectile. The specific process includes:

[0012] The technical parameters of the high-energy perforating projectile used are determined, and the initial energy of the metal jet formed by the perforating projectile is determined based on the technical parameters. The specific expression is as follows:

[0013]

[0014] In the formula, E jet Let m be the initial energy of the metal jet. jet For the jet mass, v jet The jet velocity;

[0015] S3: Determine the fracturing energy requirement of the rock mass within the target blasting area, where the specific expression for the rock mass fracturing energy is:

[0016]

[0017] In the formula, E req The energy requirement for rock mass fracture is given by α, β, γ, and δ, which are empirical coefficients related to rock mass properties. c Where φ is the compressive strength of the rock mass, φ is the porosity of the rock mass, and D is the compressive strength of the rock mass. j For joint density, K I For the dynamic fracture toughness of rock mass, V eff The volume of the area affected by the combined blasting;

[0018] S4: Determine the energy released per unit mass of the propellant and its conversion efficiency, and determine the minimum amount of propellant to be used based on the fracture energy requirement, the initial energy of the metal jet, the released energy, and the conversion efficiency. The specific expression for the minimum amount of propellant is as follows:

[0019]

[0020] In the formula, Q b For the minimum amount of propellant required, E req E is the energy required for rock mass fracturing. jet E is the initial energy of the metal jet. unitk is the energy released per unit mass of the propellant. booster For propellant energy conversion efficiency;

[0021] S5: Determine the initial stress amplitude of the booster based on the minimum dosage, and determine whether the initial stress amplitude meets the critical stress requirement for rock mass fracture. The specific expression for the initial stress amplitude is as follows:

[0022]

[0023] In the formula, σ′0 is the corrected initial stress amplitude after the propellant action, σ0 is the initial stress amplitude generated by the shaped charge jet blast, η is the efficiency of the propellant energy conversion into stress wave, and Q... b The minimum amount of propellant required, ρ is the density of the rock mass, and V is the density of the rock mass. charge σ represents the effective volume of a single perforated projectile or propellant. fracture Let γ be the critical stress for rock mass fracture, γ be the attenuation coefficient of the stress wave propagating in the rock mass, and r be the stress wave attenuation coefficient. target Pre-splitting distance of the target;

[0024] S6: Construct a final propellant dosage calculation model to determine the final propellant dosage. The specific expression is as follows:

[0025]

[0026] In the formula, Q b,实际 For the final determined propellant charge, k s For safety factor, E req E is the energy required for rock mass fracturing. jet e is the initial energy of the metal jet. -γrtarget V is the attenuation factor of the stress wave with propagation distance, σ0 is the initial stress amplitude generated by the shaped charge jet blast, and V charge Let η be the effective volume of a single perforated projectile or propellant, and let η be the efficiency of converting propellant energy into stress waves.

[0027] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a method for determining the amount of propellant used in coal mine composite blasting perforation. First, the basic mechanical parameters of the rock mass in the target blasting area are measured and determined. Then, the initial energy of the metal jet formed by the perforating projectile, the energy requirement for rock mass fracture, and the propellant energy replenishment model are defined in sequence to determine the minimum amount of propellant required. Finally, the final amount of propellant is defined by combining the initial stress amplitude after propellant replenishment. This method effectively improves blasting accuracy, reduces explosive consumption, reduces surrounding rock disturbance, and enhances roof control. It has wide application value in the fields of mine safety production and rock strata control. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 The overall flowchart of a method for determining the amount of propellant used in composite blasting perforation in coal mines provided by the present invention;

[0030] Figure 2 This is a schematic diagram of secondary splitting provided in an embodiment of the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] See Figure 1 As shown in the figure, this invention provides a method for determining the dosage of composite blasting perforation booster in coal mines, comprising the following steps:

[0033] S1: Determine the basic parameters of the rock mass within the target blasting area. The specific process includes:

[0034] Construct a sensor monitoring network and use the sensor monitoring network to transmit controllable sound waves or microseismic waves to the rock mass within the target blasting area;

[0035] By monitoring the propagation characteristics of controlled acoustic waves or microseismic waves within the rock mass, the basic parameters of the rock mass are determined using the acoustic inversion method. These basic parameters include: rock mass density, longitudinal wave propagation velocity, Poisson's ratio, dynamic elastic modulus, porosity, joint density, and compressive strength.

[0036] S2: Determine the initial energy of the metal jet formed by the perforating projectile. The specific process includes:

[0037] The technical parameters of the high-energy perforating projectile used are determined, and the initial energy of the metal jet formed by the perforating projectile is determined based on the technical parameters. The specific expression is as follows:

[0038]

[0039] In the formula, E jet The initial energy of the metal jet (J / g), m jet Let v be the jet mass (g).jet The jet velocity is (m / s).

[0040] S3: Determine the fracturing energy requirement of the rock mass within the target blasting area, where the specific expression for the rock mass fracturing energy is:

[0041]

[0042] In the formula, E req The energy requirement for rock mass fracture is given by σ (J / g), where α, β, γ, and δ are empirical coefficients related to rock mass properties. c φ represents the rock mass compressive strength (MPa), φ represents the rock mass porosity (dimensionless), and D represents the rock mass porosity. j K represents the joint density (joint length / unit volume). I Dynamic fracture toughness of rock mass (MPa·m) 1 / 2 V eff The volume of the area affected by the combined blasting (m³) 3 );

[0043] S4: Determine the energy released per unit mass of the propellant and its conversion efficiency, and determine the minimum amount of propellant to be used based on the fracture energy requirement, the initial energy of the metal jet, the released energy, and the conversion efficiency. The specific expression for the minimum amount of propellant is as follows:

[0044]

[0045] In the formula, Q b For the minimum amount of propellant required, E req For the energy requirement (J / g) for rock mass fracturing, E jet E represents the initial energy (J / g) of the metal jet. unit The energy released per unit mass of the propellant (J / g), k booster The energy conversion efficiency of the propellant (dimensionless);

[0046] S5: Determine the initial stress amplitude of the booster based on the minimum dosage, and determine whether the initial stress amplitude meets the critical stress requirement for rock mass fracture. The specific expression for the initial stress amplitude is as follows:

[0047]

[0048] In the formula, σ′0 is the corrected initial stress amplitude after the propellant action, σ0 is the initial stress amplitude generated by the shaped charge jet blast, η is the efficiency of the propellant energy conversion into stress wave, and Q... b The minimum amount of propellant required, ρ is the density of the rock mass, and V is the density of the rock mass. charge σ represents the effective volume of a single perforated projectile or propellant. fractureLet γ be the critical stress for rock mass fracture, γ be the attenuation coefficient of the stress wave propagating in the rock mass, and r be the stress wave attenuation coefficient. target Pre-splitting distance of the target;

[0049] At this point, it is necessary to ensure that the following conditions are met:

[0050]

[0051] In the formula, σ′0 is the corrected initial stress amplitude after the propellant action, i.e., the total stress wave amplitude (MPa); σ0 is the initial stress amplitude generated by the shaped charge jet blast (MPa); η is the efficiency of the propellant energy conversion into stress wave (dimensionless); and Q... b E represents the minimum amount (g) of the required propellant. unit ρ is the energy released per unit mass of the propellant (J / g), and ρ is the density of the rock mass (kg / m³). 3 V charge The effective volume (m³) of a single perforated projectile or propellant. 3 ), σ fracture Let be the critical stress for rock mass fracture (MPa), γ be the attenuation coefficient of the stress wave propagating in the rock mass (1 / m), and r be the stress wave attenuation coefficient. target The target pre-splitting distance (m);

[0052] S6: Construct a final propellant dosage calculation model to determine the final propellant dosage. The specific expression is as follows:

[0053]

[0054] In the formula, Q b,实际 For the final determined propellant charge, k s For a safety factor (typically 1.1–1.3), max{A,B}: takes the larger value between A and B, E req For the energy requirement (J / g) for rock mass fracturing, E jet E represents the initial energy (J / g) of the metal jet. unit The energy released per unit mass of the propellant (J / g), k booster σ represents the propellant energy conversion efficiency (dimensionless). fracture The critical stress (MPa) required for rock mass fracture; σ0 is the attenuation factor of the stress wave with propagation distance (dimensionless), σ0 is the initial stress amplitude (MPa) generated by the shaped charge jet blast, and ρ is the rock mass density (kg / m2). 3 V charge The effective volume (m³) of a single perforated projectile or propellant. 3 η is the efficiency (dimensionless) in which the propellant energy is converted into stress waves.

[0055] The detailed process of applying the above method is as follows:

[0056] Taking a working face in a large coal mine in Shanxi Province as an example, this working face has a hard roof, mainly composed of medium-grained sandstone, with a thickness of about 6.5m and a compressive strength of up to 80MPa. The rock integrity is relatively high, and traditional blasting or hydraulic fracturing is insufficient to create effective directional cuts, resulting in uneven roof collapse and severe pressure on the mining roadway. To improve roof control, the method for determining the dosage of composite blasting propellant in coal mines according to this invention is adopted, combining shaped charge jets with high-pressure fracturing to achieve precise roof cutting and pressure relief.

[0057] Step 1: Measure and determine the basic mechanical parameters of the rock mass within the target blasting area;

[0058] High-precision vibration sensors, acoustic sensors, and temperature sensors are deployed in the target blasting area to form a real-time monitoring network. Wireless communication technology enables rapid data acquisition and transmission, establishing a dynamic monitoring platform for the on-site rock mass. Controllable acoustic waves or microseismic waves are emitted through the sensor network to monitor their propagation characteristics within the rock mass, analyzing the dynamic changes in fundamental parameters such as temperature, pressure, and stress during the blasting process.

[0059] In this engineering case, vibration, acoustic wave, and temperature sensors were deployed, and key parameters of the rock mass were determined using acoustic wave inversion testing. Based on the measurement results, the following parameters were obtained: rock mass density ρ = 2700 kg / m³. 3 Longitudinal wave propagation speed c p =4100m / s, Poisson's ratio ν=0.28, dynamic elastic modulus E=38GPa, compressive strength σ c =80MPa, porosity φ=0.11, joint density D j =4.0m -1 .

[0060] Step 2: Define the initial energy of the metal jet formed by the perforating projectile, the specific expression is:

[0061]

[0062] In this engineering case, a high-energy perforating projectile with a diameter of 42mm and a shaped charge mass of 20g was used, achieving a metal jet velocity of 7000m / s. The metal jet energy of a single perforating projectile is as follows:

[0063]

[0064] This energy is used to penetrate rock strata, forming directional channels that provide pathways for subsequent propellant to expand the fractures.

[0065] Step 3: Define the rock mass fracturing energy requirement, the specific expression is:

[0066]

[0067] In this engineering case, the rock mass fracture influence coefficient α = 0.85, the porosity influence coefficient β = 16, the joint density influence coefficient γ = 9, and the rock dynamic fracture toughness influence coefficient δ = 45. The total energy required for rock mass fracture is as follows:

[0068] E req =(0.85×80+16×0.11+9×4.0+45×2.5)×1.8=1360.2kJ

[0069] That is, the energy requirement for rock strata fracturing within the influence range of a single perforation projectile is 1360.2 kJ.

[0070] Step 4: Define the propellant energy replenishment model to determine the minimum required amount of propellant. The specific expression is as follows:

[0071]

[0072] In this project case, such as Figure 2 As shown, using a high-efficiency smokeless propellant, the energy released per unit mass is 4200 J / g, and the energy conversion efficiency k booster =0.72. The minimum amount of propellant required is as follows:

[0073]

[0074] That is, a single perforation projectile requires at least 288g of propellant.

[0075] Step 5: Define the initial stress amplitude after propellant replenishment, the specific expression is as follows:

[0076]

[0077] Ensure that the following conditions are met:

[0078]

[0079] In this engineering case, the propellant energy conversion efficiency η = 0.6, and the explosion volume V charge =0.012m 3 The initial stress amplitude is obtained as follows:

[0080]

[0081] Considering the stress wave attenuation model, let r target =2.5m, stress wave attenuation coefficient γ = 0.70, therefore:

[0082]

[0083] This value is greater than the rock mass fracture stress σ.fracture =7.5MPa, indicating that the amount of propellant used can ensure that the stress wave can effectively propagate the crack.

[0084] Step 6: Define the final propellant dosage, the specific expression is:

[0085]

[0086] In this engineering case, a safety factor k is taken. s =1.2, resulting in the following final propellant dosage:

[0087] Q b,实际 =1.2 × max{288,310} = 372g

[0088] The final propellant dosage was determined to be 372g / well.

[0089] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0090] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining the amount of a booster for composite blasting perforating in a coal mine, characterized in that, Includes the following steps: S1: Determine the basic parameters of the rock mass within the target blasting area. The specific process includes: Construct a sensor monitoring network and use the sensor monitoring network to transmit controllable sound waves or microseismic waves to the rock mass within the target blasting area; By monitoring the propagation characteristics of controlled acoustic waves or microseismic waves within the rock mass, the basic parameters of the rock mass are determined using the acoustic inversion method. These basic parameters include: rock mass density, longitudinal wave propagation velocity, Poisson's ratio, dynamic elastic modulus, porosity, joint density, and compressive strength. S2: Determine the initial energy of the metal jet formed by the perforating projectile. The specific process includes: The technical parameters of the high-energy perforating projectile used are determined, and the initial energy of the metal jet formed by the perforating projectile is determined based on the technical parameters. The specific expression is as follows: （1） wherein is the initial energy of the metal jet, is the mass of the jet, is the velocity of the jet; S3: Determine the fracturing energy requirement of the rock mass within the target blasting area, where the specific expression for the rock mass fracturing energy is: （2） In the formula, is the rock mass fracture energy demand, α, β, γ, δ are empirical coefficients related to the characteristics of the rock mass, is the rock mass compressive strength, is the rock mass porosity, is the joint density, is the rock mass dynamic fracture toughness, V eff is the volume of the influence area of the composite blasting; S4: Determine the energy released per unit mass of the propellant and its conversion efficiency, and determine the minimum amount of propellant to be used based on the fracture energy requirement, the initial energy of the metal jet, the released energy, and the conversion efficiency. The specific expression for the minimum amount of propellant is as follows: （3） wherein, is the minimum amount of boost required, is the rock mass fracture energy requirement, is the metal jet initial energy, E unit is the energy released per unit mass of boost, k booster is the boost energy conversion efficiency; S5: Determine the initial stress amplitude of the booster based on the minimum dosage, and determine whether the initial stress amplitude meets the critical stress requirement for rock mass fracture. The specific expression for the initial stress amplitude is as follows: （4） wherein, is the initial stress amplitude after the booster effect correction, is the initial stress amplitude generated by the shaped charge blast, is the efficiency of the booster energy conversion into stress waves, is the minimum amount of booster required, and p is the rock mass density, is the effective volume of a single perforating charge or booster effect. S6: Construct a final propellant dosage calculation model to determine the final propellant dosage. The specific expression is as follows: （5） In the formula, For the final determined propellant charge, k s For safety reasons, Energy requirements for rock mass fracturing. The initial energy of the metal jet. σ is the attenuation factor of the stress wave with propagation distance. fracture This represents the critical stress for rock mass fracture. r is the attenuation coefficient of stress wave propagation in rock mass. target The target pre-splitting distance.

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