Non-coupling charge blasting hole wall pressure calculation method

Abstract

The invention discloses a non-coupling charge blasting hole wall pressure calculation method, which comprises the following steps of: pouring a plurality of groups of test blocks to carry out a blasting physical model experiment to obtain blasting hole wall pressure actual measurement data of the blasting experiment of the plurality of groups of test blocks; calibrating the blasting numerical simulation model by adopting the blasting hole wall pressure measured data, and obtaining blasting hole wall pressure simulation data under different non-coupling coefficients through the calibrated blasting numerical simulation model; performing nonlinear fitting on blast hole wall pressure simulation data by referring to a blast hole wall pressure calculation process of the uncoupled charging structure; correcting the fitted calculation formula by adopting a hole wall pressure peak value in blast hole wall pressure simulation data; and measuring and calculating the pressure peak value of the blasting hole wall without coupling charging through the corrected fitting calculation formula. According to the method, the accuracy of the calculated value of the hole wall pressure under non-coupling blasting is ensured, and the defects of high cost, tedious procedures and long period when the hole wall pressure is measured and calculated through physical model experiments and numerical simulation are overcome.

Description

Technical Field

[0001] The invention relates to a method for calculating hole wall pressure in uncoupled charge blasting, and belongs to the technical field of blasting. Background Art

[0002] In blasting projects requiring contour control, to control the excavation boundary and minimize surrounding rock damage, the blasthole must utilize an uncoupled charge structure with lower peak hole wall pressure. An uncoupled charge structure is one in which the explosive diameter is smaller than the hole diameter, leaving a gap between the explosive and the hole wall. The coupling medium within this gap and the uncoupling coefficient are two key factors in the uncoupled charge structure, which play a decisive role in the peak hole wall pressure and, in turn, influence the contour control blasting effect.

[0003] In contour-controlled blasting, the primary coupling medium is typically air. However, in actual construction, water-coupled charge blasting often occurs due to factors such as water inrush from the working face, rainfall, and rock seepage. Therefore, to improve contour blasting, it is urgent to determine the peak hole wall pressure for air- and water-coupled blasting under different decoupling coefficients.

[0004] Currently, the peak borehole pressure under different decoupling coefficients is mostly determined through experimental testing or by collecting blasting data under various coupling coefficients based on actual blasting operations. For example, Chinese patent application number CN202121661554.8 discloses a borehole pressure measurement device based on a PVDF pressure sensor. By feedback from smooth blasting data of different rock types, the decoupling spacing of the charge structure is continuously optimized. While ensuring the excavation of the rock mass, this method can effectively reduce blasting vibration and prevent rock damage. However, this method has disadvantages such as high cost, cumbersome procedures, and long data collection cycles. In addition, it can only obtain point-value data based on the specific parameters of the actual experimental blasting and cannot comprehensively cover the calculation of blasthole pressure for all decoupling coefficient charge structures. Alternatively, the blasthole pressure can be calculated according to traditional theoretical formulas. This is theoretical data obtained entirely based on the formula. Although it has the advantages of simplicity and speed, it cannot be corrected and adjusted according to the actual blasting parameters and suffers from low calculation accuracy. Summary of the Invention

[0005] The technical problem solved by the present invention is: in view of the problems that the numerical value of the blasting hole wall pressure of uncoupled blasting charge is not fully obtained by experiments and the theoretical calculation accuracy is low, a method for calculating the blasting hole wall pressure of uncoupled charge combining experimental and simulation results is provided to achieve accurate calculation of the blasting hole wall pressure numerical value with different coupling media and uncoupling coefficients.

[0006] The present invention is implemented by the following technical solutions:

[0007] A method for calculating hole wall pressure in uncoupled charge blasting includes the following steps:

[0008] S1. Cast several groups of test blocks for blasting physical model experiments. Drill blastholes on the test blocks. Use plastic tubes of different diameters to fill explosives into the blastholes to form uncoupled charge structures with different uncoupling coefficients. Detonate the uncoupled charge structures using a detonating index to obtain measured data on the blasthole wall pressure of several groups of test block blasting experiments.

[0009] S2. Establish a blasting numerical simulation model of the same test block on the LS-DYNA platform, use the measured data of the blasting hole wall pressure obtained in step S1 to input into the LS-DYNA platform to calibrate the blasting numerical simulation model, and obtain the blasting hole wall pressure simulation data under different decoupling coefficients through the calibrated blasting numerical simulation model;

[0010] S3. Referring to the theoretical calculation process of the blasting hole wall pressure of the uncoupled charge structure, nonlinear fitting is performed on the blasting hole wall pressure simulation data to obtain the fitting calculation formula of the hole wall pressure peak of the uncoupled charge structure;

[0011] S4, using the peak value of the hole wall pressure in the blasting hole wall pressure simulation data to correct the fitting calculation formula;

[0012] S5. Calculate the peak pressure of the blasting hole wall of the uncoupled charge using the revised fitting calculation formula.

[0013] In one embodiment of the method for calculating the blasting hole wall pressure of an uncoupled charge structure of the present invention, the theoretical calculation process of the blasting hole wall pressure of an uncoupled charge structure with air as the coupling medium is as follows:

[0014]

[0015] Among them, P b1 is the calculated value of the peak pressure of the blasting hole wall of the uncoupled charge structure with air as the coupling medium, P k is the critical blasting pressure of explosives, P e is the explosion pressure of the explosive, ρ e is the explosive density of the uncoupled charge structure, D is the detonation velocity of the explosive, γ is the isentropic expansion index of the explosive, χ is the adiabatic expansion index of the explosive, k is the uncoupling coefficient, and n is the pressurization coefficient.

[0016] In the above-mentioned method for calculating the hole wall pressure of an uncoupled charge blasting of the present invention, the calculation formula for the hole wall pressure of an air-coupled uncoupled charge structure blasting is further compiled into a corresponding function equation using Origin software. The blasting hole wall pressure simulation data obtained in step S2 is used as fitting data. The Levenberg-Marquardt iterative algorithm is used to perform nonlinear fitting on the blasting hole wall pressure simulation data to obtain a fitting constant a1' for the fitted air-coupled blasting. The fitted fitting constant is substituted for the boost coefficient and substituted into the original calculation formula to obtain the fitting calculation formula for the hole wall pressure of an uncoupled charge structure with air as the coupling medium, as follows:

[0017]

[0018] In the above-mentioned uncoupled charge blasting hole wall pressure calculation method of the present invention, further, according to the blasting hole wall pressure simulation data of air coupling under different uncoupled coefficients, the peak value P of the blasting hole wall pressure is calculated. m1 Calculate the correction factor

[0019]

[0020] Fitting to obtain the function of the correction coefficient under air-coupled uncoupled charge blasting with respect to the uncoupled coefficient The fitting calculation formula of the peak value of the pore wall pressure of the uncoupled charge structure after correction through air coupling is:

[0021]

[0022] In one embodiment of the method for calculating the hole wall pressure of an uncoupled charge blasting structure of the present invention, according to the calculation formula for the hole wall pressure of an uncoupled charge structure blasting structure coupled with air, a dimensionally harmonic equation for the hole wall pressure of an uncoupled charge structure blasting structure with water as the coupling medium is constructed as follows:

[0023]

[0024] P b2 is the calculated value of the peak pressure of the blasting hole wall of the uncoupled charge structure with water as the coupling medium, P j is the detonation pressure of explosive, ρ m is the density of the test block, ρ w is the coupling medium density, ρ e is the explosive density of the uncoupled charge structure, v p is the longitudinal wave velocity of the test piece in the blasting of the uncoupled charge structure, v w is the underwater shock wave velocity of the explosive with uncoupled charge structure, D is the detonation velocity of the explosive, k is the uncoupling coefficient, γ is the isentropic expansion index of the explosive, a2, b, c are the constants of the state equation under water coupled blasting.

[0025] In the above-mentioned method for calculating the hole wall pressure of an uncoupled charge blasting of the present invention, further, the dimensionally harmonic equation of the hole wall pressure of the water-coupled uncoupled charge structure blasting is compiled into a corresponding function equation using Origin software. The blasting hole wall pressure simulation data obtained in step S2 is used as fitting data. The Levenberg-Marquardt iterative algorithm is used to perform nonlinear fitting on the blasting hole wall pressure simulation data to obtain the fitting constants a2', b', and c' of the fitted water-coupled blasting. The fitting constants are substituted into the original calculation formula to obtain the fitting calculation formula for the hole wall pressure of the uncoupled charge structure with water as the coupling medium, as follows:

[0026]

[0027] In the above-mentioned uncoupled charge blasting hole wall pressure calculation method of the present invention, further, according to the blasting hole wall pressure simulation data of different uncoupled coefficients, the peak value P of the blasting hole wall pressure of the water coupling is calculated. m2 Calculate the correction factor

[0028]

[0029] The function of the correction coefficient of the water-coupled uncoupled charge blasting with respect to the uncoupled coefficient is obtained by fitting. The fitting calculation formula of the peak value of the pore wall pressure of the uncoupled charge structure after water coupling is:

[0030]

[0031] In the above-mentioned method for calculating the blasting hole wall pressure of the uncoupled charge blasting of the present invention, further, in the step S1, a PVDF piezoelectric film is used in the specimen blasting hole to obtain the measured data of the blasting hole wall pressure during the blasting experiment.

[0032] In the above-mentioned method for calculating the blasthole wall pressure of an uncoupled charge blasting of the present invention, further, in the step S1, the detonating cord is covered with a steel pipe wrapped with EVA tape at the blasthole exit section to reduce the impact of the detonating cord transmission on the measured data of the blasthole wall pressure.

[0033] In the above-mentioned method for calculating the hole wall pressure of an uncoupled charge blasting of the present invention, further, in the step S1, a water medium is added between the plastic tube and the inner wall of the blasthole of the specimen, and hot melt adhesive and rubber mud are used to seal the plastic tube and the bottom and outlet of the blasthole of the specimen to form an uncoupled charge structure in which the coupling medium is water.

[0034] The present invention first casts cement test blocks to carry out physical model experiments of uncoupled charge blasting under different uncoupling coefficients, and uses PVDF piezoelectric film to collect the borehole wall pressure signal of the test block during the blasting process to obtain the measured data of blasting hole wall pressure that is closer to the real blasting scene. At the same time, an LS-DYNA blasting numerical simulation model of the same size calibrated based on the measured data of blasting hole wall pressure is established to obtain more blasting hole wall pressure simulation data under uncoupling coefficients. The traditional calculation formula of hole wall pressure is fitted and corrected through a large amount of blasting hole wall pressure simulation data, and a correction coefficient that changes with the uncoupling coefficient is defined. The correction formula is used to calculate the universality of hole wall pressure for various types of uncoupled charge blasting.

[0035] Based on the above technical solution, the present invention has the following beneficial effects:

[0036] (1) The method for calculating the hole wall pressure of uncoupled charge blasting provided by the present invention can measure the peak value of the hole wall pressure of blasting with the coupling medium being air and water under different uncoupling coefficients, thereby improving the accuracy of calculating the peak value of the hole wall pressure of different coupling media between the uncoupled charge structure and the blasthole during the actual blasting construction process.

[0037] (2) Due to the limited blasting parameters and cost considerations of the physical model experiment, the present invention uses the LS-DYNA blasting numerical simulation model to obtain uncoupled charge blasting hole wall pressure simulation data under more uncoupled coefficients, which increases the continuity of the blasting hole wall pressure calculation formula for subsequent fitting of the blasting hole wall pressure peak value. In addition, the LS-DYNA blasting numerical simulation model is calibrated by the hole wall pressure measured data that is closer to the real blasting to ensure the authenticity of the obtained blasting hole wall pressure simulation data. Based on the calibrated numerical simulation model, a more comprehensive air and water coupled blasting simulation with different uncoupled coefficients is carried out to obtain more accurate and effective hole wall pressure peak value data.

[0038] (3) The present invention modifies the calculation formula of the peak value of the hole wall pressure in the uncoupled charge blasting according to the variation law of the peak value of the hole wall pressure with the uncoupling coefficient. The modified formula takes into account the continuity condition of the collision interface and the interaction between the shock wave in water and the hole wall, thereby obtaining a more practical and accurate curve of the peak value of the hole wall pressure changing with the uncoupling coefficient.

[0039] (4) The present invention ultimately provides a modified mathematical calculation formula to calculate and measure the peak pressure of the uncoupled charge blasting hole wall with different coupling media under different coupling coefficients. The process is simpler than the measurement using physical experimental models and simulation experimental models. Compared with obtaining the blasting hole wall pressure data through physical measurement models, the present invention has lower costs and can quickly obtain more accurate blasting data with a short measurement cycle. Compared with simulating the blasting hole wall pressure data by establishing a blasting numerical simulation model, the present invention reduces the number of modeling times and does not require a large amount of computer computing power to complete the measurement of the blasting hole wall pressure data. Compared with the existing technology, it has the advantages of lower cost, faster speed and higher accuracy.

[0040] In summary, the present invention corrects the calculation process of the hole wall pressure of uncoupled blasting through the measured data of the physical model experiment and the simulation data of the numerical simulation model, thereby realizing a simpler method for calculating the hole wall pressure of uncoupled charge blasting, which can not only ensure the accuracy of the calculated value of the hole wall pressure under uncoupled blasting, but also avoid the shortcomings of high cost, cumbersome procedures and long cycle in the physical model experiment and numerical simulation to measure the hole wall pressure.

[0041] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The figure is a flow chart of a method for calculating hole wall pressure in uncoupled charge blasting according to the present invention.

[0043] Figure 2 Schematic diagram of the uncoupled charge structure in the embodiment, where the numbers are: 1-blast hole, 2-blocking material, 3-explosive, 4-detonating cord, 5-detonating cap, 6-coupling medium, 7-PVDF piezoelectric film, 8-EVA tape, 9-steel pipe.

[0044] Figure 3a and Figure 3b They are respectively the fitting curves of the uncoupled explosion theoretical model curves of air coupling and water coupling and the simulation data in the embodiment.

[0045] Figure 4a and Figure 4b These are the relationship diagrams between the correction coefficient and the uncoupled coefficient in uncoupled blasting with air coupling and water coupling respectively. DETAILED DESCRIPTION

[0046] Example

[0047] See also Figure 1 The method for calculating the hole wall pressure of an uncoupled charge blasting process of the present invention specifically comprises the following steps:

[0048] S1. Cast several groups of test blocks for blasting physical model experiments. Drill blastholes on the test blocks. Use plastic tubes of different diameters to fill explosives and load them into the blastholes to form uncoupled charge structures with different uncoupling coefficients. The uncoupled charge structures are detonated using detonating indexes to obtain measured data on the blasthole wall pressure of several groups of test block blasting experiments.

[0049] Cement mortar is used to cast test blocks to simulate the dynamic response of brittle rock materials under explosive loads. Different grades of cement are used to simulate different blasting geological rock strengths. A drill is used to drill a through hole of a set diameter in the center of the test block after casting. The uncoupling coefficient of the uncoupled charge structure is the ratio of the hole diameter to the charge diameter. Plastic tubes of different diameters (one end is sealed with hot melt adhesive) smaller than the hole diameter are used to fill explosives to simulate charge structures with different uncoupling coefficients. One specific uncoupled charge structure is as follows: Figure 2 As shown, the bottom of the blasthole 1 is blocked and sealed with a plugging material 2 such as gun mud, and the explosive 3 is loaded into a plastic tube to form a strip-shaped charge with a diameter smaller than the diameter of the blasthole and loaded into the blasthole 1. The explosive 3 is detonated by a detonating cord 4, wherein the installation direction and detonation direction of the detonating line are from bottom to top, the detonating cord 4 is led out of the blasthole and connected to the detonating detonator 5, and a PVDF piezoelectric film 7 is used in the blasthole to detect the measured data of the blasting hole wall pressure during the test block blasting experiment. The PVDF piezoelectric film 7 is set on the inner wall of the blasthole 1 and is led out of the blasthole through a signal line to communicate with the NUXI-1004 ultra-dynamic monitor to collect the measured signal of the blasting hole wall pressure. In order to prevent the air shock wave caused by the detonator detonation from damaging the film foot line before the PVDF piezoelectric film measures the effective explosion pressure data, the piezoelectric film foot line is installed in a direction from top to bottom. Considering that the detonating cord is only used to detonate explosive charges, the detonating cord 4 is covered with a steel tube 9 wrapped with EVA tape 8 at the blasthole exit section to reduce the impact of the detonating cord transmission on the measured data of the blasthole wall pressure.

[0050] The coupling medium 6 is located between the plastic tube and the inner wall of the blasthole. According to the actual blasting situation, the coupling medium 6 includes air and water. For the uncoupled charge blasting model experiment in which the coupling medium is water, hot melt adhesive and rubber mud are required to seal the bottom of the blasthole to prevent the water coupling medium filled between the powder bag and the hole wall from leaking from the bottom of the hole.

[0051] S2. Establish a blasting numerical simulation model of the same test block on the LS-DYNA platform. Use the measured data of the blasting hole wall pressure obtained in step S1 to input the LS-DYNA platform to calibrate the blasting numerical simulation model. Use the calibrated blasting numerical simulation model to obtain the simulation data of the blasting hole wall pressure under different decoupling coefficients.

[0052] Due to experimental cost and the diameter of the plastic tube used for the coupled charge, the blasting physics model experiment in step S1 can only consider a limited number of decoupling coefficients. Furthermore, some PVDF piezoelectric films are difficult to monitor for valid data during the decoupled charge blasting experiment. Therefore, a blasting numerical simulation model equivalent to that in step S1 was established using LS-DYNA. This blasting numerical simulation model was calibrated using the blasting physics model of the experimental specimen in step S1 and the measured blasting hole wall pressure data obtained. This allowed the generation of peak blasting hole wall pressures for a wider range of decoupled charge structures.

[0053] The establishment of a blasting simulation model on the LS-DYNA platform is a conventional simulation experiment. The experimental specimen parameters and the same explosive structure parameters of step S1 can be used as modeling parameters to construct a blasting physical model equivalent to step S1. Therefore, in order to accurately describe the rock dynamic response under explosive dynamic load, the calibration of the constructed blasting numerical simulation model is completed based on the measured data of the blasting hole wall pressure detected in step S1. The peak value of the blasting hole wall pressure under the uncoupling coefficient in the blasting physical model experiment of multiple groups of specimens in step S1, as well as the relevant rock physical and mechanical parameters of the specimens such as density, wave velocity, elastic modulus, Poisson's ratio, compressive strength, tensile strength, and the density and detonation velocity of the explosives are selected. The blasting numerical simulation model constructed on the LS-DYNA platform is calibrated to make the simulated peak value of the blasting hole wall pressure close to the peak value of the blasting hole wall pressure measured in step S1. Generally, the error between the two is within 15%, which is considered to be parameter calibration completed. Then, the calibrated blasting numerical simulation model outputs the blasting hole wall pressure simulation data.

[0054] S3. Referring to the calculation process of the blasting hole wall pressure of the uncoupled charge structure, nonlinear fitting is performed on the blasting hole wall pressure simulation data to obtain the fitting calculation formula of the hole wall pressure peak of the uncoupled charge structure.

[0055] Specifically, the blast hole wall pressure of the uncoupled charge structure with air as the coupling medium is calculated by the following formula:

[0056]

[0057] Among them, P b1 is the calculated value of the peak pressure of the blast hole wall in the air-coupled uncoupled charge structure, P k is the critical detonation pressure of the explosive, which is used to divide the isentropic expansion and adiabatic expansion processes of the explosive detonation products. It is a constant, P e is the explosion pressure of the explosive, ρ e is the explosive density of the uncoupled charge structure, D is the detonation velocity of the explosive, γ is the isentropic expansion index of the explosive, χ is the adiabatic expansion index of the explosive, k is the uncoupling coefficient, and n is the pressurization coefficient.

[0058] The calculation formula for the blasting hole wall pressure of the air-coupled uncoupled charge structure is compiled into a corresponding function equation using the function plotting data analysis software Origin. The blasting hole wall pressure simulation data obtained in step S2 is used as the fitting data. The Levenberg-Marquardt iterative algorithm is used to perform nonlinear fitting on the blasting hole wall pressure simulation data to obtain the fitting constant a1' of the fitted air-coupled blasting. The fitted fitting constant a1' is substituted for the pressurization coefficient n and substituted into the original calculation formula to obtain the fitting calculation formula for the hole wall pressure peak of the uncoupled charge structure with the coupling medium being air as follows:

[0059]

[0060] In the prior art, the theoretical calculation formula for the blast hole wall pressure of an uncoupled charge structure with water as the coupling medium is as follows:

[0061]

[0062]

[0063] Among them, P b is the calculated value of the peak pressure of the blasting hole wall of the uncoupled charge structure, P I is the incident pressure on the water-rock medium surface, ρ m is the density of the test block, ρ w is the coupling medium density, ρ e is the explosive density of the uncoupled charge structure, v p is the longitudinal wave velocity of the test piece in the blasting of the uncoupled charge structure, v w is the underwater shock wave velocity of the uncoupled charge structure, D is the explosive detonation velocity, k is the uncoupling coefficient, B and α are the underwater shock wave peak pressure attenuation coefficients, A' and n' are the state equation constants of water under isentropic conditions, Q s The explosive heat and Q of the uncoupled charge structure t The theoretical value of the peak value of the hole wall pressure calculated under the water-coupled blasting in this embodiment is still obtained by the above theoretical calculation formula.

[0064] However, considering the difference between water coupling and air coupling in the calculation method of the hole wall pressure of the uncoupled charge blasting structure, this embodiment follows the air coupling uncoupled charge structure blasting hole wall pressure calculation formula and constructs the dimensional harmony equation of the uncoupled charge structure blasting hole wall pressure with the coupling medium being water by the principle of dimensional harmony as follows:

[0065]

[0066] Among them, P b2 is the calculated value of the peak pressure of the blasting hole wall of the uncoupled charge structure, Pj is the detonation pressure of explosive, ρ m is the density of the test block, ρ w is the coupling medium density, ρ e is the explosive density of the uncoupled charge structure, v p is the longitudinal wave velocity of the test piece in the blasting of the uncoupled charge structure, v w is the underwater shock wave velocity of the uncoupled charge structure, D is the explosive detonation velocity, k is the uncoupling coefficient, and γ is the isentropic expansion index of the explosive. The dimensional and harmonious equation of the blasting hole wall pressure of the water-coupled uncoupled charge structure refers to and adopts the calculation form of the hole wall pressure peak of the air-coupled uncoupled charge structure to construct the blasting hole wall pressure peak value P of the water-coupled uncoupled charge structure. b P j A linear function of the component dimension and harmony equation, a2, b, c are the state equation constants, and are the fitting constants that need to be fitted in the next step of this implementation.

[0067] The calculation formula of the blasting hole wall pressure data of the water-coupled uncoupled charge structure is compiled into a corresponding function equation using the Origin software. The blasting hole wall pressure simulation data obtained in step S2 is used as the fitting data. The Levenberg-Marquardt iterative algorithm is used to perform nonlinear fitting on the blasting hole wall pressure simulation data to obtain the fitting constants a2', b', and c' of the fitted water-coupled blasting. The fitting constants a2', b', and c' are substituted into the original calculation formula to obtain the fitting calculation formula for the hole wall pressure of the uncoupled charge structure with water as the coupling medium as follows:

[0068]

[0069] S4. Use the peak value of the hole wall pressure in the blasting hole wall pressure simulation data to correct the fitting calculation formula.

[0070] The calculations in step S3 reveal that, for both air-coupled and water-coupled uncoupled charge blasting, correcting the fitting constants a1' and a2' is highly beneficial for quickly and easily calculating the peak pressure. Therefore, to make the fitting formula for the peak pressure of an uncoupled charge structure more universal, it is necessary to correct the fitting constants a1' and a2' used to calculate the peak pressure of an uncoupled charge structure under different operating conditions.

[0071] Among them, the peak value of blasting hole wall pressure P under different uncoupling coefficients in the blasting hole wall pressure simulation data using air coupling is m1 Calculating the Correction Factor for Air-Coupled Blasting

[0072]

[0073] For the correction coefficients corresponding to different decoupling coefficients, the least squares method is used for linear fitting regression to obtain the function of the correction coefficient with respect to the decoupling coefficient under air-coupled decoupling charge blasting. Generally a linear function A1 and B1 are the linear constants obtained by fitting. The fitting calculation formula for the peak value of the pore wall pressure of the uncoupled charge structure coupled with air after correction is:

[0074]

[0075] The peak value P of blasting hole wall pressure under different decoupling coefficients in the blasting hole wall pressure simulation data using water coupling m2 Calculation of Correction Factors for Water-Coupled Blasting

[0076]

[0077] For the correction coefficients corresponding to different uncoupling coefficients, the least squares method is used for linear fitting regression.

[0078] The function of the correction coefficient of water-coupled uncoupled charge blasting with respect to the uncoupled coefficient is obtained A2 and B2 are the linear constants obtained by fitting. The fitting calculation formula for the peak value of the pore wall pressure of the uncoupled charge structure after water coupling is:

[0079]

[0080] The least squares method is a well-known and mature linear fitting method. This embodiment does not elaborate on the specific fitting process of the correction coefficient function.

[0081] S5. Calculate the peak pressure of the blasting hole wall of the uncoupled charge using the modified fitting calculation formula.

[0082] The present invention is described in detail below by taking a specific example of calculating the hole wall pressure of an uncoupled charge blasting.

[0083] use Figure 2 The uncoupled charge structure in the explosive is PETN powder. In the air-coupled uncoupled charge structure, the density of the test block is ρ m =2110kg / m 3 , explosive density ρ e =1200kg / m 3 , explosive detonation velocity D = 6250m / s, explosive isentropic expansion index γ = 3, explosive adiabatic expansion index χ = 1.3, explosive blasting critical pressure P k =200MPa, pressure coefficient n=8; in the water-coupled uncoupled charge structure, the test block density ρm =2110kg / m 3 , explosive density ρ e =1200kg / m 3 , the density of the coupling medium water ρ w =1000kg / m 3 , longitudinal wave velocity v of the test block in the blasting of uncoupled charge structure p =3744m / s. B = 72MPa and α = 0.72 are constants in the formula for attenuation of the peak pressure of underwater shock waves; the explosive heat of PETN, Q s =5895kJ / kg and the explosion heat of TNT Q t =4200kJ / kg; the state equation constants of water under isentropic conditions are A'=394MPa and n'=8.

[0084] When the uncoupling coefficient k is 3, 4.3, 5.3 and 7 respectively, under water-coupled blasting, the percentage errors between the theoretical value of the peak value of the hole wall pressure calculated and the simulated value of the blasting hole wall pressure of the blasting numerical simulation model in step S2 are 57%, 10%, 11% and 31% respectively. Figure 3b As shown in , compared with the measured value of the hole wall pressure of the test block blasting in step S1, when the uncoupling coefficient k = 4.3 and 5, the error of the theoretical value is 5% and 30% respectively. When the uncoupling coefficient k is 3, 4.3, 5.3 and 7 respectively, under air coupling blasting, the percentage error between the theoretical value of the hole wall pressure peak value calculated and the simulated value of the blasting hole wall pressure of the blasting numerical simulation model in step S2 is 29%, 64%, 87% and 123% respectively. Figure 3b As shown in , compared with the measured values of the blast hole wall pressure of the test block in step S1, the deviations of the theoretical values are 72.1, 89.5, 97.3 and 44.8 MPa, respectively, and the corresponding percentage errors are 18%, 58%, 108% and 101%, respectively.

[0085] It can be seen that the theoretical value of the peak value of the blasting hole wall pressure calculation is too different from the experimental measured value and the numerical simulation value. In step S3 of the present invention, the air-coupled and water-coupled blasting hole wall pressure calculation formulas are respectively fitted and optimized, and the parameters of the test block and the explosive are substituted into the fitted and optimized calculation formulas to obtain the peak value function of the air-coupled uncoupled charge blasting hole wall pressure as P b1 =a1'863.8k -2.6 The peak value function of the hole wall pressure of the water-coupled uncoupled charge blasting is P b2 =11718.8a1'5.27 b' k c'Based on the above function model, the Levenberg-Marquardt iterative algorithm is used to perform nonlinear fitting on the blasting hole wall pressure simulation data obtained by the blasting numerical simulation model in step S2. It is found that the fitting state equation constant a1' under air-coupled blasting is 7.5, and the fitting state equation constants a2', b' and c' under water-coupled blasting are 14.4, 6.4 and -1.3.

[0086] Through the above process, it can be found that the correction of the state equation constants a1' and a2' can quickly and efficiently calculate the peak pressure of the blasting hole wall of the air-coupled and water-coupled charge structures under different decoupling coefficient conditions. According to the blasting hole wall pressure peak value of the blasting numerical simulation model in step S4 of the present invention, the correction coefficient of the blasting of the air-coupled decoupled charge structure is defined as

[0087]

[0088] The correction factor for the blasting of the uncoupled charge structure with water coupling is

[0089]

[0090] In air-coupled blasting, the relationship between different decoupling coefficients and correction coefficients is shown in the following table:

[0091] Table 1. Relationship between uncoupling coefficient and correction coefficient in air-coupled blasting

[0092]

[0093] In water-coupled blasting, the relationship between different decoupling coefficients and correction coefficients is shown in the following table:

[0094] Table 2 Relationship between uncoupling coefficient and correction coefficient in water coupling blasting

[0095]

[0096] The least squares method is used to perform linear fitting regression on the uncoupling coefficients and their corresponding correction coefficients in Table 1, and the functional equation of the correction coefficient with respect to the uncoupling coefficient under air-coupled uncoupled charge blasting is obtained as follows:

[0097]

[0098] Function graph Figure 4a As shown in the figure, the calculation formula for the hole wall pressure of the uncoupled charge blasting with air coupling after correction is:

[0099] P b1 =(2.128k+4.444)P k (P e / P k )0.43 (1 / k) 2.6 .

[0100] The least squares method is used to perform linear fitting regression on the uncoupling coefficients and their corresponding correction coefficients in Table 2. The functional equation of the correction coefficient with respect to the uncoupling coefficient under water-coupled uncoupled charge blasting is:

[0101]

[0102] Function graph Figure 4b As shown in the figure, the calculation formula for the hole wall pressure of the uncoupled charge blasting with air coupling after correction is:

[0103] P b2 =(-1.098k+17.959)P j (ρ m v p / ρ w v w ) 6.4 k -1.3 .

[0104] The calculation result obtained by the above-mentioned revised uncoupled charge blasting hole wall pressure calculation formula is compared with the blasting hole wall pressure simulation data in step S2, and the error does not exceed 4%. Compared with the traditional theoretical calculation results, the revised calculation formula can give a more accurate uncoupled charge blasting hole wall pressure peak value, especially for a smaller uncoupling coefficient.

[0105] In this document, the directions or positional relationships indicated by terms such as "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "vertical", and "horizontal" are based on the directions or positional relationships shown in the accompanying drawings and are only for the clarity of the technical solution and the convenience of description, and therefore should not be understood as limiting the present invention.

[0106] As used herein, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion of elements other than the listed elements and may also include additional elements not specifically listed.

[0107] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for calculating hole wall pressure in uncoupled charge blasting, characterized by: The steps include: S1. Cast several groups of test blocks for blasting physical model experiments. Drill blastholes on the test blocks. Use plastic tubes of different diameters to fill explosives into the blastholes to form uncoupled charge structures with different uncoupling coefficients. Detonate the uncoupled charge structures using a detonating index to obtain measured data on the blasthole wall pressure of several groups of test block blasting experiments. S2. Establish a blasting numerical simulation model of the same test block on the LS-DYNA platform, use the measured data of the blasting hole wall pressure obtained in step S1 to input into the LS-DYNA platform to calibrate the blasting numerical simulation model, and obtain the blasting hole wall pressure simulation data under different decoupling coefficients through the calibrated blasting numerical simulation model; S3. Referring to the theoretical calculation process of the blasting hole wall pressure of the uncoupled charge structure, nonlinear fitting is performed on the blasting hole wall pressure simulation data to obtain the fitting calculation formula of the hole wall pressure peak of the uncoupled charge structure; S4, using the peak value of the hole wall pressure in the blasting hole wall pressure simulation data to correct the fitting calculation formula; S5. Calculate the peak pressure of the blasting hole wall of the uncoupled charge using the revised fitting calculation formula.

2. The method for calculating hole wall pressure in uncoupled charge blasting according to claim 1, characterized in that: The theoretical calculation process of the blast hole wall pressure of the uncoupled charge structure with air as the coupling medium is as follows: Among them, P b1 is the calculated value of the peak pressure of the blasting hole wall of the uncoupled charge structure with air as the coupling medium, P k is the critical blasting pressure of explosives, P e is the explosion pressure of the explosive, ρ e is the explosive density of the uncoupled charge structure, D is the detonation velocity of the explosive, γ is the isentropic expansion index of the explosive, χ is the adiabatic expansion index of the explosive, k is the uncoupling coefficient, and n is the pressurization coefficient.

3. The method for calculating hole wall pressure in uncoupled charge blasting according to claim 2, characterized in that: The calculation formula for the blasting hole wall pressure of the air-coupled uncoupled charge structure is compiled into a corresponding function equation using the Origin software. The blasting hole wall pressure simulation data obtained in step S2 is used as the fitting data. The Levenberg-Marquardt iterative algorithm is used to perform nonlinear fitting on the blasting hole wall pressure simulation data to obtain the fitting constant a1' of the fitted air-coupled blasting. The fitted fitting constant is substituted for the boost coefficient and substituted into the original calculation formula to obtain the fitting calculation formula for the hole wall pressure of the uncoupled charge structure with air as the coupling medium as follows:

4. The method for calculating hole wall pressure in uncoupled charge blasting according to claim 3, characterized in that: According to the blasting hole wall pressure simulation data, the peak value P of the blasting hole wall pressure under different uncoupling coefficients of air coupling is m1 Calculate the correction factor Fitting to obtain the function of the correction coefficient under air-coupled uncoupled charge blasting with respect to the uncoupled coefficient The fitting calculation formula of the peak value of the pore wall pressure of the uncoupled charge structure after correction through air coupling is:

5. The method for calculating hole wall pressure in uncoupled charge blasting according to claim 4, characterized in that: According to the calculation formula of the blasting hole wall pressure of the uncoupled charge structure with air coupling, the dimensional and harmonious equation of the blasting hole wall pressure of the uncoupled charge structure with water as the coupling medium is constructed as follows: P b2 is the calculated value of the peak pressure of the blasting hole wall of the uncoupled charge structure with water as the coupling medium, P j is the detonation pressure of explosive, ρ m is the density of the test block, ρ w is the coupling medium density, ρ e is the explosive density of the uncoupled charge structure, v p is the longitudinal wave velocity of the test piece in the blasting of the uncoupled charge structure, v w is the underwater shock wave velocity of the explosive with uncoupled charge structure, D is the detonation velocity of the explosive, k is the uncoupling coefficient, γ is the isentropic expansion index of the explosive, a2, b, c are the constants of the state equation under water coupled blasting.

6. The method for calculating hole wall pressure in uncoupled charge blasting according to claim 5, characterized in that: The dimensionless harmonic equation of the blasting hole wall pressure of the water-coupled uncoupled charge structure is compiled into a corresponding function equation using the Origin software. The blasting hole wall pressure simulation data obtained in step S2 is used as the fitting data. The Levenberg-Marquardt iterative algorithm is used to perform nonlinear fitting on the blasting hole wall pressure simulation data to obtain the fitting constants a2', b', and c' of the fitted water-coupled blasting. The fitting constants are substituted into the original calculation formula to obtain the fitting calculation formula for the hole wall pressure of the uncoupled charge structure with water as the coupling medium as follows:

7. The method for calculating hole wall pressure in uncoupled charge blasting according to claim 6, characterized in that: According to the blasting hole wall pressure simulation data with different uncoupling coefficients, the peak value P of the blasting hole wall pressure of water coupling is m2 Calculate the correction factor The function of the correction coefficient of the water-coupled uncoupled charge blasting with respect to the uncoupled coefficient is obtained by fitting. The fitting calculation formula of the peak value of the pore wall pressure of the uncoupled charge structure after water coupling is:

8. The method for calculating hole wall pressure in uncoupled charge blasting according to any one of claim 1, characterized in that: In step S1, a PVDF piezoelectric film is used in a blast hole of a specimen to obtain measured data of blast hole wall pressure during a blasting experiment.

9. A method for calculating hole wall pressure in uncoupled charge blasting according to any one of claim 1, characterized in that: In step S1, the detonating cord is covered with a steel tube wrapped with EVA tape at the blasthole exit section to reduce the impact of the detonating cord on the measured data of the blasthole wall pressure.

10. A method for calculating hole wall pressure in uncoupled charge blasting according to any one of claims 5 to 7, characterized in that: In step S1, water medium is added between the plastic tube and the inner wall of the blasthole of the specimen, and hot melt adhesive and rubber mud are used to seal the plastic tube and the bottom and outlet of the blasthole of the specimen to form an uncoupled charge structure with water as the coupling medium.

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