A method for designing a single-hole blasting crack propagation and lateral blasting crater test

Abstract

The application provides a single-hole blasting crack propagation and lateral blasting crater test design method, which comprises the following steps: obtaining test parameters, determining a blast hole charging structure design parameter, obtaining a blasting critical resistance line according to the blast hole charging structure design parameter, obtaining a square sample, cutting the rock sample according to the blasting critical resistance line to obtain the square sample, obtaining a test sample, setting a variable as a curvature radius of an arc free surface and a blasting resistance line by controlling the position of the blast hole and the arc free surface, drilling the blast hole and the arc free surface on a plurality of square samples to obtain the test sample, performing blasting test, charging the blast hole on each test sample, performing blasting, and obtaining the blasting crack propagation under the condition of the arc free surface. The application is convenient for studying the blasting crack propagation law under different arc free surface conditions, and provides support for the lateral blasting crater theory, and is convenient for analyzing the relationship between the volume of the lateral blasting crater under the arc free surface and the specific charge of the explosive.

Description

Technical Field

[0001] This invention relates to the field of blasting technology research, specifically to a test design method for single-hole blasting crack propagation and lateral blasting funnel. Background Technology

[0002] Currently, the mainstream construction method for vertical inclined shafts in hydropower, mining and other engineering fields is reverse drilling + drilling and blasting expansion to form a shaft. That is, firstly, a 1.4 to 2.5m pilot shaft is excavated using reverse drilling, which is used as a chute for subsequent drilling and blasting expansion in the main shaft method. Then, the shaft is expanded from top to bottom by blasting using the drilling and blasting method.

[0003] Reasonable borehole layout parameters are crucial to ensuring effective rock-breaking blasting. During well enlargement using the drill-and-blast method, the blasting free face is typically arc-shaped. However, current blasting design parameters are based on the funnel theory of a straight free face, which does not reflect reality. Furthermore, there are few research reports on the rock-breaking and well enlargement mechanism of columnar explosive charges blasting under arc-shaped free faces. Summary of the Invention

[0004] The purpose of this invention is to propose a test design method for single-hole blast crack propagation and lateral blast funnel, which facilitates the study of blast crack propagation laws under different arc-shaped free surface conditions, and provides support for the theory of lateral blast funnel, making it easier to analyze the relationship between the volume of the lateral blast funnel and the explosive consumption under arc-shaped free surface conditions.

[0005] To achieve the above objectives, the present invention mainly adopts the following technical solutions:

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a test design method for single-hole blast crack propagation and lateral blast funnel, including the following steps:

[0007] A method for designing a single-hole blast crack propagation and lateral blast funnel test includes the following steps:

[0008] Obtain test parameters, determine the design parameters of the borehole charge structure, and obtain the critical resistance line of blasting based on the design parameters of the borehole charge structure.

[0009] To obtain square specimens, the rock sample was cut according to the critical resistance line of the blasting.

[0010] Test specimens are obtained by controlling the positions of the boreholes and the arc-shaped free surface, and setting variables such as the radius of curvature of the arc-shaped free surface and the blasting resistance line. Boreholes and arc-shaped free surfaces are drilled on multiple square specimens to obtain test specimens.

[0011] A blasting test was conducted, in which explosives were loaded into the boreholes of each test specimen and blasted to obtain the propagation of blast cracks under the condition of an arc-shaped free surface.

[0012] Furthermore, based on the determined borehole radius r p Length of charge l b Charge amount (m) b Calculate the charge radius r using the following formulas respectively. b Radial decoupling coefficient ξ:

[0013]

[0014]

[0015] In the formula, ρ0 is the density of the explosive.

[0016] Furthermore, the critical resistance line W for blasting L Calculate using the following formula:

[0017]

[0018] In the formula, p d λ is the peak explosive load pressure on the borehole wall after detonation; λ is the lateral pressure coefficient, λ=μ / (1-μ), μ is the dynamic Poisson's ratio of the rock, within the loading rate range of engineering blasting, μ=0.8μ0, μ0 is the static Poisson's ratio of the rock; K is the reflection coefficient; S T It represents the tensile strength of the rock.

[0019] Furthermore, the peak explosion load pressure p on the borehole wall after the explosive detonation d The calculation is performed using equation (4):

[0020]

[0021] The reflection coefficient K is calculated using equation (5):

[0022]

[0023] In the formula, ρ0 is the density of the explosive; D0 is the detonation velocity of the explosive; ρ r C represents the density of the rock sample. rp ρ is the longitudinal wave velocity of the rock sample; κ is the isentropic exponent of the detonation products; η is the stress wave amplification factor, which is generally approximated as 8; ρ a C is the density of air. ap The longitudinal wave velocity of the stress wave in the air.

[0024] Furthermore, the side length of the square specimen is 3 to 4 times the critical resistance line of the blast.

[0025] Furthermore, during the design of the test plan, the first set of test samples and the second set of test samples were obtained;

[0026] In the first group of test specimens, the size of the blast resistance line corresponding to each arc-shaped free surface is an invariant, and the radius of curvature of the arc-shaped free surface is a variable;

[0027] In the second group of test specimens, the radius of curvature of the arc-shaped free surface is invariant, while the size of the blast resistance line corresponding to each arc-shaped free surface is variable.

[0028] Furthermore, the arc-shaped free surface is located at the middle of the test specimen, on the side of the test specimen, or at the corner of the test specimen. When the arc-shaped free surface is located at the middle of the test specimen, the arc-shaped free surface is an empty hole.

[0029] Furthermore, when the position of the arc-shaped free surface is set on the side or corner of the test specimen, the number of arc-shaped free surfaces is 1, 2 or 4 respectively.

[0030] Furthermore, when there are two arc-shaped free surfaces, the two arc-shaped free surfaces are symmetrically set.

[0031] Furthermore, the radius of curvature of the arc-shaped free surface is greater than 1 / 4 of the side length of the test specimen and less than 1 / 2 of the side length of the square specimen.

[0032] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0033] This invention determines the design parameters of the borehole charge structure, obtains the critical resistance line of blasting based on the design parameters, and sets up a suitable square specimen according to the critical resistance line of blasting. This facilitates subsequent blasting tests and prevents the square specimen from being too large and heavy, which would be uneconomical, or too small, where reflections from other straight edges would affect the test results. In the process of designing the test scheme, by controlling the position of the borehole and the arc-shaped free surface, and setting variables such as the radius of curvature of the arc-shaped free surface and the blasting resistance line, boreholes and arc-shaped free surfaces are drilled on multiple square specimens to form test specimens. This allows for comprehensive testing with a relatively small number of tests and low complexity. This invention provides an experimental design process for studying scientific issues related to blasting under arc-shaped free surfaces, and can provide support for studying the crack propagation mechanism and lateral blasting funnel theory under arc-shaped free surface conditions. The blasting test design method is comprehensive, efficient, and convenient. Attached Figure Description

[0034] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and are intended to explain the invention, but do not constitute an undue limitation thereof. In the drawings:

[0035] Figure 1 This is a schematic diagram of the experimental design method of the present invention;

[0036] Figure 2(a) is a schematic diagram of the first test scheme for single-hole blasting under free surfaces with different curvatures according to the present invention;

[0037] Figure 2(b) is a schematic diagram of the second test scheme for single-hole blasting under free surfaces with different curvatures according to the present invention;

[0038] Figure 2(c) is a schematic diagram of the third test scheme for single-hole blasting under free surfaces with different curvatures according to the present invention;

[0039] Figure 2(d) is a schematic diagram of the fourth test scheme for single-hole blasting under free surfaces with different curvatures according to the present invention;

[0040] Figure 2(e) is a schematic diagram of the fifth test scheme for single-hole blasting under free surfaces with different curvatures according to the present invention;

[0041] Figure 2(f) is a schematic diagram of the sixth test scheme for single-hole blasting under free surfaces with different curvatures according to the present invention;

[0042] Figure 2(g) is a schematic diagram of the seventh test scheme for single-hole blasting under free surfaces with different curvatures according to the present invention;

[0043] Figure 3(a) is a schematic diagram of the first test scheme for single-hole blasting under different blasting resistance lines under the arc-shaped free surface of the present invention;

[0044] Figure 3(b) is a schematic diagram of the second test scheme for single-hole blasting under different blasting resistance lines under the arc-shaped free surface of the present invention;

[0045] Figure 3(c) is a schematic diagram of the third test scheme for single-hole blasting under different blasting resistance lines under the arc-shaped free surface of the present invention;

[0046] Figure 3(d) is a schematic diagram of the fourth test scheme for single-hole blasting under different blasting resistance lines under the arc-shaped free surface of the present invention;

[0047] Figure 3(e) is a schematic diagram of the fifth test scheme for single-hole blasting under different blasting resistance lines under the arc-shaped free surface of the present invention;

[0048] Figure 3(f) is a schematic diagram of the sixth test scheme for single-hole blasting under different blasting resistance lines under the arc-shaped free surface of the present invention;

[0049] Figure 3(g) is a schematic diagram of the seventh test scheme for single-hole blasting under different blasting resistance lines under the arc-shaped free surface of the present invention;

[0050] Figure 4(a) is a schematic diagram of the single-hole blasting test scheme under arc-shaped free surfaces with different radii of curvature in a specific embodiment of the present invention;

[0051] Figure 4(b) is a schematic diagram of the single-hole blasting test scheme under arc-shaped free surfaces with different radii of curvature in working condition 2 of the present invention in a specific embodiment of the present invention;

[0052] Figure 5(a) is a schematic diagram of a single-hole blasting test scheme with different blasting resistance lines under the arc-shaped free surface in a specific embodiment of the present invention;

[0053] Figure 5(b) is a schematic diagram of a single-hole blasting test scheme with different blasting resistance lines under the arc-shaped free surface in a specific embodiment of the present invention;

[0054] Figure 6 This is a schematic diagram of the square sample of the present invention;

[0055] Figure 7(a) is a schematic diagram of actual rock samples from single-hole blasting under arc-shaped free surfaces with different radii of curvature in working condition 1 of the present invention.

[0056] Figure 7(b) is a schematic diagram of actual rock samples from single-hole blasting under arc-shaped free surfaces with different radii of curvature in embodiment 2 of the present invention;

[0057] Figure 8(a) is a schematic diagram of actual rock samples from single-hole blasting under different blasting resistance lines in working condition 1 of the present invention.

[0058] Figure 8(b) is a schematic diagram of actual rock samples from single-hole blasting under different blasting resistance lines in working condition 2 of the present invention.

[0059] Among them, 1. square specimen; 2. test specimen; 3. blast hole; 4. arc-shaped free surface. Detailed Implementation

[0060] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0061] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0062] This invention provides a method for designing single-hole blast crack propagation and lateral blast funnel tests, such as... Figure 1 As shown, it includes the following steps:

[0063] Step S1: Obtain test parameters, determine the design parameters of the charge structure of borehole 3, and obtain the critical resistance line of blasting based on the design parameters of the charge structure of borehole 3;

[0064] Step S2: Obtain square sample 1 by cutting the rock sample according to the critical resistance line of blasting.

[0065] Step S3: Obtain test specimen 2. By controlling the position of the blast hole and the arc-shaped free surface, and setting the variables as the radius of curvature of the arc-shaped free surface and the blast resistance line, blast holes 3 and arc-shaped free surfaces 4 are drilled on multiple square specimens 1 to obtain test specimen 2.

[0066] Step S4: Conduct a blasting test. Charge explosives into the boreholes 3 on each test specimen 2 and blast them to obtain the blast crack propagation under the condition of the arc-shaped free surface 4.

[0067] This invention determines the design parameters of the charge structure of borehole 3, obtains the critical resistance line of blasting based on the design parameters of the charge structure of borehole 3, and sets a suitable square specimen 1 according to the critical resistance line of blasting, which facilitates subsequent blasting tests. It prevents the square specimen 1 from being too large and heavy, which would be uneconomical, and prevents the square specimen 1 from being too small, which would affect the test results due to the reflection of other straight edges. In the process of designing the test scheme, by controlling the position of borehole 3 and the position of arc-shaped free surface 4, and setting the variables as the radius of curvature of arc-shaped free surface 4 and the blasting resistance line, borehole 3 and arc-shaped free surface 4 are drilled on multiple square specimens 1 to form test specimens 2. This allows for comprehensive testing with a relatively small number of tests and low complexity. This invention provides an experimental design process for studying scientific issues related to blasting under arc-shaped free surface 4, and can provide support for studying the crack propagation mechanism and lateral blasting funnel theory under arc-shaped free surface 4 conditions. The blasting test design method is comprehensive, efficient and convenient.

[0068] In this invention, in step S1, the design parameters of the charging structure of the borehole 3 include the radius r of the borehole 3. p Length of charge l b Charge amount (m) b Calculate the charge radius r using the following formulas respectively. b Radial decoupling coefficient ξ:

[0069]

[0070]

[0071] In the formula, ρ0 is the density of the explosive.

[0072] In this invention, in step S1, the critical resistance line W for blasting is calculated based on the design parameters of the charge structure of borehole 3. L Calculate using the following formula:

[0073]

[0074] In the formula, p d λ is the peak explosive load pressure on the borehole wall after detonation; λ is the lateral pressure coefficient, λ=μ / (1-μ), μ is the dynamic Poisson's ratio of the rock, within the loading rate range of engineering blasting, μ=0.8μ0, μ0 is the static Poisson's ratio of the rock; K is the reflection coefficient; S T It represents the tensile strength of the rock.

[0075] Among them, the peak explosion load pressure p on the borehole wall after the explosive detonation d The calculation is performed using equation (4):

[0076]

[0077] The reflection coefficient K is calculated using equation (5):

[0078]

[0079] In the formula, ρ0 is the density of the explosive; D0 is the detonation velocity of the explosive; ρ r C represents the density of the rock sample. rp ρ is the longitudinal wave velocity of the rock sample; κ is the isentropic exponent of the detonation products; η is the stress wave amplification factor, which is generally approximated as 8; ρ a C is the density of air. ap The longitudinal wave velocity of the stress wave in the air.

[0080] In this invention, such as Figure 6 The diagram shows a square specimen 1. In order to obtain the burst crack propagation mechanism under the condition of arc-shaped free surface 4, the side length of the square specimen 1 is 3 to 4 times the critical resistance line of the burst.

[0081] In this invention, the crack propagation mechanism under the condition of arc-shaped free surface 4 is obtained through two sets of test specimens 2.

[0082] During the design of the test plan, the first set of test specimens 2 and the second set of test specimens 2 were obtained;

[0083] In the first group of test specimens 2, the size of the blast resistance line corresponding to each arc-shaped free surface 4 is an invariant, while the radius of curvature of the arc-shaped free surface 4 is a variable. That is, the size of the blast resistance line corresponding to each arc-shaped free surface 4 is the same, while the position of the borehole 3, the radius of curvature of the arc-shaped free surface 4, and the position of the arc-shaped free surface 4 are different.

[0084] In the second group of test specimens 2, the radius of curvature of the arc-shaped free surface 4 is invariant, while the size of the blast resistance line corresponding to each arc-shaped free surface 4 is variable. That is, the radius of curvature of the arc-shaped free surface 4 is the same, but the size of the blast resistance line corresponding to each arc-shaped free surface 4, the position of the borehole 3, the radius of curvature of the arc-shaped free surface 4, and the position of the arc-shaped free surface 4 are different.

[0085] In this invention, in the first group of test specimens 2 and the second group of test specimens 2, the arc-shaped free surface 4 is respectively located in the middle of the square specimen 1, on the side of the square specimen 1, or on the corner of the square specimen 1.

[0086] In this invention, when the arc-shaped free surface 4 is located in the middle of the square sample 1 in the first group of test specimens 2 and the second group of test specimens 2, the arc-shaped free surface 4 is a hollow hole.

[0087] In this invention, in the first group of test specimens 2 and the second group of test specimens 2, when the position of the arc-shaped free surface 4 is set on the side or vertex of the square specimen 1, the number of arc-shaped free surfaces 4 is 1, 2 or 4 respectively. When the number of arc-shaped free surfaces 4 is 2, the two arc-shaped free surfaces 4 are symmetrically arranged.

[0088] In the first group of test specimens 2, the size of the blast resistance line is the same, but the position of the borehole 3, the radius of curvature of the arc-shaped free surface 4, and the position of the arc-shaped free surface 4 are different.

[0089] Specifically, the design of the single-hole blasting test scheme for arc-shaped free surfaces 4 with different curvatures mainly focuses on the processing shape of specimens with arc-shaped free surfaces 4 containing different radii of curvature. This involves the design of the position of the arc-shaped free surfaces 4 and the dimensions of the arc-shaped free surfaces 4 with different radii of curvature, offering multiple design options. This embodiment lists seven selectable design schemes, as shown in Figure 2. Figure 2(a) shows the scheme design under confining pressure conditions; Figures 2(b) to (d) show the schemes for processing the arc-shaped free surfaces 4 on the sides of the test specimen 2, with the specimens corresponding to 1, 2, and 4 radii of curvature of the arc-shaped free surfaces 4, respectively; Figures 2(e) to (g) show the schemes for processing the arc-shaped free surfaces 4 at the corners of the test specimen 2, with the specimens corresponding to 1, 2, and 4 arc curvatures, respectively.

[0090] In the second group of test specimens 2, the radius of curvature of the arc-shaped free surface 4 is the same, but the size of the blast resistance line, the position of the borehole 3, the radius of curvature of the arc-shaped free surface 4, and the position of the arc-shaped free surface 4 are different.

[0091] In order to obtain all the burst crack propagation mechanisms of the arc-shaped free surface 4 and to prevent the reflection of other straight edges from affecting the test results if the square specimen 1 is too small, the radius of curvature of the arc-shaped free surface 4 is greater than 1 / 4 of the side length of the square specimen 1 and less than 1 / 2 of the side length of the square specimen 1.

[0092] In a specific embodiment of the present invention, the design of a single-hole blasting test scheme for different blasting resistance lines under the arc-shaped free surface 4 mainly focuses on the processing shape of specimens with different blasting resistance lines under the same curvature arc-shaped free surface 4, involving the design of the position of the borehole 3, and has multiple design schemes to choose from. This embodiment lists a total of 7 selectable design schemes, as shown in Figure 3. Figure 3(a) shows the scheme design under confining pressure conditions; Figures 3(b) to (d) show the schemes for processing the arc-shaped free surface 4 on the side of the test specimen 2, with the specimens corresponding to 1, 2, and 4 blasting resistance lines respectively; Figures 3(e) to (g) show the schemes for processing the arc-shaped free surface 4 at the corner of the test specimen 2, with the specimens corresponding to 1, 2, and 4 blasting resistance lines respectively.

[0093] Select a test scheme and conduct blasting tests. Based on actual needs, select a single-hole blasting test scheme with different curvatures of the arc-shaped free surface 4 and a single-hole blasting test scheme with different blasting resistance lines under the arc-shaped free surface 4 to conduct blasting tests.

[0094] In a specific embodiment of the present invention, this embodiment provides an example of an experimental design for the propagation of cracks and the lateral blasting funnel of a single-hole arc-shaped free surface under no confining pressure, formulated according to the above-described experimental design method. The steps are as follows:

[0095] 1) Determine the design parameters of the charging structure for borehole 3, first determining the radius r of borehole 3. p 10mm, charge length l b 10mm, charge amount m b The quantities are 1.0g, 1.5g, 2.0g, 2.5g, and 3.0g, with the following explosive parameters: density ρ0 is 1300kg / m³. 3 If the detonation velocity D0 is 4000 m / s, then the charge radius r under different charge structures can be calculated according to equations (1) and (2). b The uncoupling coefficient ξ is shown in Table 1.

[0096] Calculate the critical resistance line of blasting, and calculate the radius of destruction R / critical resistance line W under different charge structures according to equations (3) to (5). L The results are shown in Table 1. The mechanical parameters of the rock samples are shown in Table 2.

[0097] Table 1 Blasting parameters for different charge amounts

[0098]

[0099] Table 2 Rock mechanical parameters

[0100]

[0101] 2) Determining the dimensions of square specimen 1: Based on the calculation results of the critical resistance line for blasting, the proposed charge amount is m.b The value is 2.0g, at which point the critical resistance line W for explosive detonation is... L The final sample size was determined to be 117 mm. The final sample size was determined to be a thin plate of 400 mm × 400 mm × 30 mm (length × width × thickness).

[0102] 3) Single-hole blasting test design under free surfaces 4 with different curvatures: Under the same blasting resistance line and charge amount, two sets of tests were designed, with three test specimens in each set. The test design scheme shown in Figure 2(f) was selected. The blasting test design schemes under free surfaces 4 with different curvature radii are shown in Table 3. The design dimensions of test specimen 2 are shown in Figures 4(a) and 4(b). The schematic diagrams of the actual rock samples of test specimen 2 are shown in Figures 7(a) and 7(b).

[0103] Table 3. Test design for blasting under free surfaces with different curvatures.

[0104]

[0105] 4) Single-hole blasting test design under different blasting resistance lines under the arc-shaped free surface 4: Under the same radius of curvature arc-shaped free surface 4 and charge amount, two sets of tests were designed, with three test specimens in each set. The test design scheme shown in Figure 3(f) was selected. The blasting test design schemes under arc-shaped free surfaces 4 with different curvatures are shown in Table 4. The design dimensions of test specimen 2 are shown in Figures 5(a) and 5(b). The schematic diagrams of the actual rock samples of test specimen 2 are shown in Figures 8(a) and 8(b).

[0106] Table 4. Test Design for Blasting at Different Blasting Resistance Lines under Arc-Shaped Free Surface

[0107]

[0108] According to the above design, a blasting test was carried out to obtain the blast crack propagation under the arc-shaped free surface 4 condition, which provides support for the theory of lateral blasting funnel and facilitates the analysis of the relationship between the volume of the lateral blasting funnel under the arc-shaped free surface 4 and the explosive consumption.

[0109] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for designing a single-hole blast crack propagation and lateral blast funnel test, characterized in that, Includes the following steps: Obtain test parameters, determine the design parameters of the borehole charge structure, and obtain the critical resistance line of blasting based on the design parameters of the borehole charge structure. To obtain square specimens, the rock sample was cut according to the critical resistance line of the blasting. Test specimens are obtained by controlling the positions of the boreholes and the arc-shaped free surface, and setting variables such as the radius of curvature of the arc-shaped free surface and the blasting resistance line. Boreholes and arc-shaped free surfaces are drilled on multiple square specimens to obtain test specimens. A blasting test was conducted, and explosives were loaded into the boreholes of each test specimen and blasted to obtain the propagation of blast cracks under the condition of an arc-shaped free surface. Based on the determined borehole radius r p Length of charge l b , charge amount m b Calculate the charge radius using the following formulas respectively. r b Radial decoupling coefficient ξ : Equation (1) Equation (2) In the formula, ρ 0 represents the density of the explosive; Explosive critical resistance line W L Calculate using the following formula: Equation (3) In the formula, p d This represents the peak value of the explosive load pressure on the borehole wall after the explosive detonates. The lateral pressure coefficient, , The dynamic Poisson's ratio of the rock is within the loading rate range of engineering blasting. , The static Poisson's ratio of the rock; K The reflection coefficient; S T Tensile strength of rock; Peak explosive load pressure on the borehole wall after detonation p d The calculation is performed using equation (4): Equation (4) Reflectance coefficient K Calculations are performed using equation (5): Equation (5) In the formula, Density of the explosive; For the detonation velocity of the explosive; Density of the rock sample; The longitudinal wave velocity of the rock sample; The isentropic index of the detonation products; This is the stress wave amplification factor; air density; The longitudinal wave velocity of the stress wave in the air.

2. The test design method for single-hole blast crack propagation and lateral blast funnel according to claim 1, characterized in that: The side length of the square specimen is 3 to 4 times the critical resistance line of the blast.

3. The test design method for single-hole blast crack propagation and lateral blast funnel according to claim 1, characterized in that: During the design of the test plan, the first set of test samples and the second set of test samples were obtained; In the first group of test specimens, the size of the blast resistance line corresponding to each arc-shaped free surface is an invariant, and the radius of curvature of the arc-shaped free surface is a variable; In the second group of test specimens, the radius of curvature of the arc-shaped free surface is invariant, while the size of the blast resistance line corresponding to each arc-shaped free surface is variable.

4. The test design method for single-hole blast crack propagation and lateral blast funnel according to claim 3, characterized in that: The arc-shaped free surface is located at the middle of the test specimen, on the side of the test specimen, or at the corner of the test specimen. When the arc-shaped free surface is located at the middle of the test specimen, the arc-shaped free surface is an empty hole.

5. The test design method for single-hole blast crack propagation and lateral blast funnel according to claim 4, characterized in that: When the position of the arc-shaped free surface is set on the side or corner of the test specimen, the number of arc-shaped free surfaces is 1, 2 or 4 respectively.

6. The test design method for single-hole blast crack propagation and lateral blast funnel according to claim 5, characterized in that: When there are two curved free surfaces, the two curved free surfaces are set symmetrically.

7. The test design method for single-hole blast crack propagation and lateral blast funnel according to claim 1, characterized in that: The radius of curvature of the arc-shaped free surface is greater than 1 / 4 of the side length of the test specimen and less than 1 / 2 of the side length of the square specimen.

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