Quantitative evaluation of rock-breaking effects of explosion stress waves and blasting gas and rock blasting methods

Abstract

The embodiment of the present invention discloses a quantitative evaluation method of the rock-breaking effect of explosion stress wave and blasting gas, and a rock blasting method, wherein the evaluation method includes: setting a plurality of relative position relationships between explosives and blastholes, wherein the explosives are located in the blastholes and there is a cavity between the explosives and the blasthole wall, and the volume of the cavity between the explosives and the blasthole wall in the direction of the measured position of the rock under different relative position relationships is different; for each relative position relationship: placing the explosives at the corresponding position in the blasthole, using the explosion effect of the explosives in the blasthole to apply a load to the rock to destroy the rock; based on the stress conditions and / or damage conditions of the measured position of the rock during the rock destruction process under various relative position relationships, the rock-breaking effect of the explosion stress wave and the blasting gas is quantitatively evaluated. The embodiment of the present invention can be applied to the experimental scene of the study of the action mechanism of the explosion stress wave and the blasting gas, and realizes the accurate identification and quantification of the rock-breaking effect of the coupling of the explosion stress wave and the blasting gas.

Description

Technical Field

[0001] The invention relates to the field of blasting analysis, and in particular to a quantitative evaluation of the rock-breaking effect of explosion stress waves and explosive gas and a rock blasting method. Background Art

[0002] Blasting is a technology that uses the compression, loosening, destruction, throwing and killing effects of explosives in air, water, soil and rock media or objects to achieve the desired purpose. In the early stage of blasting, under the action of high-pressure explosion products, the medium is compressed, and a stress wave propagating outward (called explosion stress wave) is generated in it. At the same time, explosive gas is generated in the chamber and expands to the surroundings. The surrounding medium is compacted or broken under the action of strong high pressure, and cracks are formed. Explosion stress waves and explosion gases are the main driving forces for rock blasting and crushing. Explaining the effects of explosion stress waves and explosion gases is an important basis for revealing the basic theory of rock blasting.

[0003] In the prior art, the study of the rock-breaking mechanism of explosion stress waves and explosion gas usually adopts the means of model experiments, which are often implemented through some equivalent processing means, such as using the method of shielding the explosion gas to study the dynamic effect of the explosion stress wave in the medium, or studying the energy distribution of the explosion gas by ignoring the effect of the explosion stress wave. However, this kind of equivalent processing model experiment means is difficult to stand on the scientific basis of the experimental design, because the explosion stress wave and the explosion gas are actually generated simultaneously.

[0004] Due to the difficulty of experimental research, numerical simulation has become the main means of studying the effects of explosion stress waves and explosion gas. The loading characteristics of explosion stress waves are simulated by applying different load curves to the hole wall, and the effects of explosion gas are analyzed by controlling the corresponding relationship between gas volume and pressure in the crack. However, the research results of numerical simulation also have obvious limitations. The current numerical simulation technology uses more equivalence and simplification, which cannot present the physical process of the generation and action of explosion stress waves and explosion gas, and lacks reliable experimental verification. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a quantitative evaluation method of the rock-breaking effect of explosion stress wave and blasting gas and a rock blasting method, so as to more accurately identify and quantify the rock-breaking effect of the coupled explosion stress wave and blasting gas.

[0006] In a first aspect, an embodiment of the present invention provides a method for quantitatively evaluating the rock-breaking effect of explosion stress waves and explosion gas, the method comprising:

[0007] Set various relative position relationships between the explosive and the blast hole, where the explosive is located inside the blast hole and there is a cavity between the explosive and the blast hole wall, and the cavity volume between the explosive and the blast hole wall in the direction of the explosive to the measured position of the rock is different under different relative position relationships;

[0008] For each of the above-mentioned relative position relationships: Place the explosive at the corresponding position in the blast hole, and use the explosion of the explosive in the blast hole to apply a load to the rock to cause the rock to break;

[0009] Based on the stress conditions and / or failure conditions of the measured position of the rock during the rock failure process under various relative position relationships, quantitatively evaluate the rock-breaking effect of the explosion stress wave and the explosion-generated gas.

[0010] Furthermore, the various relative position relationships between the explosive and the blast hole include:

[0011] The first relative position relationship is: the direct contact area between the explosive charge and the blast hole wall is the first area S1, and the cavity volume between the explosive and the blast hole wall in the direction of the explosive to the measured position of the rock is the first volume V1;

[0012] The second relative position relationship is: the direct contact area between the explosive charge and the blast hole wall is the second area S2, and the cavity volume between the explosive and the blast hole wall in the direction of the explosive to the measured position of the rock is the second volume V2;

[0013] The nth relative position relationship is: the direct contact area between the explosive charge and the blast hole wall is the second area S2, and the cavity volume between the explosive and the blast hole wall in the direction of the explosive to the measured position of the rock is the nth volume Vn;

[0014] Among them, S1 > S2, V1 < V2, Vn - 1 < Vn, and n takes values in sequence as 3, 4... until N, where N is the total number of types of various relative position relationships between the explosive and the blast hole.

[0015] Furthermore, the shapes of the explosive charge and the blast hole are both prisms, and they only differ in the edge lengths;

[0016] Place the bottom surface of the explosive charge against the bottom surface of the blast hole and place it inside the blast hole, and relatively move it along the edge direction in the blast hole to obtain various relative position relationships between the explosive and the blast hole.

[0017] Furthermore, the shapes of the explosive charge and the blast hole are both cylinders, and they only differ in the heights;

[0018] Place the bottom surface of the explosive charge against the bottom surface of the blast hole and place it inside the blast hole, and relatively move it along the height direction in the blast hole to obtain various relative position relationships between the explosive and the blast hole.

[0019] Furthermore, the prism is a cuboid; the blast hole is equally divided into M along the edge direction, M is greater than or equal to N; the edge length of the explosive charge is equal to

[0020] The i-th relative position relationship is: the explosive package is located at the length of the blast hole to where 1≤i≤M.

[0021] Furthermore, when M is an even number, N is equal to

[0022] When M is an odd number, N is equal to

[0023] Furthermore, based on the stress and / or damage of the rock during the rock destruction process under various relative position relationships, the rock-breaking effects of the explosion stress wave and the explosion gas are quantitatively evaluated, including:

[0024] Based on the changes in stress magnitude and stress distribution of rocks over time during rock failure under various relative position relationships:

[0025] Conduct blast strain evolution analysis to quantitatively assess the separation of blast stress waves from the rock-breaking effects of the blasting gases; and / or

[0026] Conduct explosion strain peak analysis to quantitatively evaluate the effects of various relative position relationships on the explosion stress wave and the rock-breaking effect of the blast gas; and / or

[0027] Explosion crack analysis is performed to quantitatively evaluate the effects of various relative position relationships on explosion crack propagation.

[0028] Furthermore, the explosive is lead azide; the rock is replaced by polycarbonate material or organic glass material.

[0029] In a second aspect, an embodiment of the present invention further provides a rock blasting method, the method comprising:

[0030] Placing explosives in the blast hole, wherein there is a cavity between the explosives and the blast hole wall, and the size of the cavity is set according to the requirements for the blasting effect;

[0031] The blasting action of explosives in the blast hole is used to apply load to the rock, causing it to fail;

[0032] Among them, the blasting effect is related to the stress characteristics of the rock, the stress characteristics of the rock are controlled by the explosion stress wave and the rock-breaking effect of the explosive gas, and the explosion stress wave and the rock-breaking effect of the explosive gas are related to the size of the cavity.

[0033] Furthermore, the explosion stress wave and the rock-breaking effect of the blasting gas are associated with the size of the cavity, including at least one of the following situations:

[0034] As the volume of the cavity increases, the rock-breaking effect of the explosion stress wave gradually weakens, and the effect of the explosion gas on rock stress gradually increases; when the cavity volume reaches a preset threshold, the rock-breaking effect of the explosion stress wave is reduced, and the rock-breaking effect of the explosion gas is suppressed;

[0035] With the increase of cavity volume, the rock crack extension length caused by stress concentration gradually increases, while the rock crack extension length controlled by the vertical stress component first increases and then decreases.

[0036] The technical solution provided by the embodiment of the present invention regulates the separation of the effects of the explosion stress wave and the explosion gas by changing the charge structure of the blast hole and setting cavities of different sizes between the explosive bag and the blast hole wall during the actual explosion process in which the explosion stress wave and the explosion gas are coupled to break the rock. Therefore, the rock-breaking effects of the explosion stress wave and the explosion gas can be evaluated based on the regulation results, and the evaluation results are true and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 A schematic diagram of the steps of a method for quantitatively evaluating the rock-breaking effect of explosion stress waves and blasting gas provided in the first embodiment of the present invention;

[0039] Figure 2 A schematic diagram of multiple relative position relationships between explosives and blastholes and measured positions provided in the second embodiment of the present invention;

[0040] Figure 3 Another schematic diagram of multiple relative position relationships between explosives and blastholes and measured positions provided in the second embodiment of the present invention;

[0041] Figure 4 A schematic diagram of three groups of test pieces required for an evaluation provided in the second embodiment of the present invention;

[0042] Figure 5 The explosion Mises strain evolution cloud diagram of three groups of test pieces provided in the second embodiment of the present invention;

[0043] Figure 6 A schematic diagram of the positions of the measuring points of three groups of test pieces provided in the second embodiment of the present invention;

[0044] Figure 7A strain time history curve of a relevant test piece measuring point provided in the second embodiment of the present invention;

[0045] Figure 8 A variation law of the peak value of strain in the y direction with the volume of the cavity provided in the second embodiment of the present invention;

[0046] Fig. 9 A curve diagram showing the attenuation of the peak value of strain with distance provided in the second embodiment of the present invention;

[0047] Fig.10 A schematic diagram of the distribution state of cracks around a blasthole after detonation of an explosive provided in the second embodiment of the present invention;

[0048] Fig.11 A distribution diagram of explosion cracks of three groups of test pieces after blasting provided in Example 2 of the present invention;

[0049] Fig.12 A curve showing the variation of the length of an explosion crack with the volume of a cavity provided in the second embodiment of the present invention. DETAILED DESCRIPTION

[0050] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0051] It should be clear that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] Embodiment 1

[0053] This embodiment provides a method for quantitatively evaluating the rock-breaking effect of explosion stress waves and explosive gas, including the following steps 101-103.

[0054] Step 101, setting a plurality of relative position relationships between the explosive and the blasthole, wherein the explosive is located in the blasthole and there is a cavity between the explosive and the blasthole wall.

[0055] Among them, the setting of multiple relative position relationships between explosives and blastholes should isolate the respective effects of explosion stress waves and explosive gas to the greatest extent. After the explosion of the explosives, the explosion stress wave quickly acts on the blasthole wall and then transmits to the measured position of the rock. At the same time, the high-pressure explosive gas generated compresses the cavity gas for a relatively long time, thereby distinguishing its effect from the effect of the previous explosion stress wave in terms of time scale, and realizing the separation study of the explosion stress wave and the explosion gas effect. Therefore, the purpose of different relative position relationships between the explosive and the blasthole can be achieved by changing the cavity volume between the explosive and the blasthole wall in the direction from the explosive to the measured position of the rock.

[0056] In specific implementation, various relative position relationships between the explosive and the blast hole can be set according to the following two parameters: the size of the direct contact area between the explosive charge and the blast hole wall, and the size of the cavity volume between the explosive and the blast hole wall in the direction from the explosive to the measured position of the rock. Specifically, it can include:

[0057] The first relative position relationship is that the direct contact area between the explosive charge and the blast hole wall is the first area S1, and the cavity volume between the explosive and the blast hole wall in the direction from the explosive to the measured position of the rock is the first volume V1;

[0058] The second relative position relationship is that the direct contact area between the explosive charge and the blast hole wall is the second area S2, and the cavity volume between the explosive and the blast hole wall in the direction from the explosive to the measured position of the rock is the second volume V2;

[0059] The nth relative position relationship is that the direct contact area between the explosive charge and the blast hole wall is the second area S2, and the cavity volume between the explosive and the blast hole wall in the direction from the explosive to the measured position of the rock is the nth volume Vn;

[0060] Among them, S1 > S2, V1 < V2, Vn - 1 < Vn, and n takes values in sequence as 3, 4... up to N, where N is the total number of types of various relative position relationships between the explosive and the blast hole.

[0061] Exemplarily, the shapes of both the explosive charge and the blast hole are prisms, and they only differ in the edge lengths. Place the bottom surface of the explosive charge against the bottom surface of the blast hole and place it in the blast hole, and relative movement along the edge direction in the blast hole can obtain various relative position relationships between the explosive and the blast hole.

[0062] As a preferred method, the prism is a cuboid; the blast hole is equally divided into M along the edge direction, M is greater than or equal to N; the edge length of the explosive charge is equal to

[0063] The ith relative position relationship is that the explosive charge is located at to of the blast hole length, where 1 ≤ i ≤ M.

[0064] In the above preferred method, the position where the bottom surface of the explosive charge is placed against the bottom surface of the blast hole in the blast hole is located at 0 to of the blast hole length. The measured position of the rock is at the rock position that is at a distance of R from the explosive in the opposite direction of the moving direction of the explosive during the relative movement, where R is greater than the numerical value of the edge length of the blast hole. N can take the value of M. As Figure 2 shown.

[0065] More preferably, N can be less than M. Specifically, when M is an even number, N is equal to When M is an odd number, N is equal to In this method, in a blasthole charging structure, there can be two relative position relationships, corresponding to two measured rock positions respectively: the rock position at a distance R from the explosive in the opposite direction of the moving direction of the explosive during the relative movement; and the rock position at a distance R from the explosive in the moving direction of the explosive during the relative movement. Assume that in a blasthole charging structure: the volume of the cavity between the explosive and the blasthole wall in the direction from the explosive to the measured rock position 1 is Q1, the volume of the cavity between the explosive and the blasthole wall in the direction from the explosive to the measured rock position 2 is Q2, and the volume of the explosive charge is Q3, then Q1+Q2+Q3=blasthole volume. Figure 3 shown.

[0066] Of course, those skilled in the art should understand that the shapes of the explosive package and the blast hole can also be cylindrical, and only differ in height. The bottom surface of the explosive package is attached to the bottom surface of the blast hole and placed in the blast hole, and relatively moved in the blast hole along the height direction to obtain a variety of relative positional relationships between the explosive and the blast hole, which is not specifically limited in this embodiment.

[0067] Step 102: for each relative position relationship, explosives are placed at corresponding positions in the blastholes, and the blasting effect of the explosives in the blastholes is used to apply loads to the rocks to destroy the rocks.

[0068] It should be noted that, in this embodiment, multiple groups of test specimens for evaluation may be pre-arranged, each group of test specimens for evaluation includes rocks, explosives and blastholes, wherein the explosives are placed in the blastholes for blasting the rocks. Except for the different blasthole charge structures, other conditions of each group of test specimens for evaluation are the same, and different blasthole charge structures are specifically arranged according to different relative position relationships between the explosives and the blastholes in step 101.

[0069] Typically, in this embodiment, the explosive in the test piece is lead azide, and the rock is replaced by polycarbonate material or organic glass material. In addition, in order to prevent the explosion gas from leaking prematurely during the explosion of the explosive, a special fixture is used to block the blast hole in advance.

[0070] Step 103: Based on the stress conditions and / or damage conditions of the rock at the measured position during the rock destruction process under various relative position relationships, the rock-breaking effects of the explosion stress wave and the explosion gas are quantitatively evaluated.

[0071] Based on the stress and / or damage of rocks during the rock destruction process under various relative position relationships, the rock-breaking effects of explosion stress waves and explosive gases are evaluated, including:

[0072] Based on the changes in stress magnitude and stress distribution of rocks over time during rock failure under various relative position relationships:

[0073] Conduct blast strain evolution analysis to quantitatively assess the separation of blast stress waves from the rock-breaking effects of the blasting gases; and / or

[0074] Conduct explosion strain peak analysis to quantitatively evaluate the effects of various relative position relationships on the explosion stress wave and the rock-breaking effect of the blast gas; and / or

[0075] Explosion crack analysis is performed to quantitatively evaluate the effects of various relative position relationships on explosion crack propagation.

[0076] Embodiment 2

[0077] This embodiment provides a specific example based on the above-mentioned embodiment 1.

[0078] In this embodiment, see Figure 4 A rectangular borehole with a length of 20 mm and a width of 4 mm is prefabricated in the middle of the specimen, and the borehole is divided into five equal parts along the length direction. The explosive is placed in a 4 mm × 4 mm square charge. There are three relative positions of the charge in the five-equal borehole, namely, one-fifth of the borehole length (specimen S1), two-fifths of the borehole length (specimen S2), and three-fifths of the borehole length (specimen S3). There are obvious differences in the constraints between the explosive and the borehole under these three conditions. For specimen S1: the upper end, lower end, and left end of the charge are in direct contact with the borehole wall, and the right side of the charge is air; during blasting, the upper end, lower end, and left end can be regarded as coupled charges, while the right end can be regarded as uncoupled charges. For specimen S2: the upper and lower ends of the explosive package are in direct contact with the wall of the blasthole, and the left and right sides of the explosive package are air; during blasting, the upper and lower ends can be regarded as coupled charges, while the left and right ends can be regarded as uncoupled charges. For specimen S3: the upper and lower ends of the explosive package are in direct contact with the wall of the blasthole, and the left and right sides of the explosive package are air, but the lengths of the air columns on both sides are the same, which is different from specimen S2; during blasting, the upper and lower ends can be regarded as coupled charges, while the left and right ends can be regarded as uncoupled charges.

[0079] In the above three groups of specimens, the total volume of the cavities on the left and right sides of the explosive package is the same, both of which are 4V. For specimen S1, the volume of the cavity on the left side of the explosive package is 0, and the volume of the cavity on the right side is 4V; for specimen S2, the volume of the cavity on the left side of the explosive package is V, and the volume of the cavity on the right side is 3V; for specimen S3, the volume of the cavities on both sides of the explosive package is 2V. The explosive used in the experiment is lead azide, the charge of a single explosive package is 120mg, and the explosive is detonated by high-voltage probe discharge. In addition, in order to study the evolution of explosion strain and the expansion of explosion cracks, polycarbonate and plexiglass are used as specimen materials respectively. Among them, when studying the evolution of explosion strain, polycarbonate is used as the specimen material, and the blasting process is photographed and recorded by high-speed photography, and the evolution process of the explosion strain field is calculated by combining digital image correlation method. When studying the expansion of explosion cracks, plexiglass is used as the specimen material, and the distribution state of explosion cracks is observed and analyzed.

[0080] The following is an introduction to explosion strain analysis based on the above three groups of specimens.

[0081] 1. Analysis of explosion strain evolution

[0082] Use special clamps to block the blast hole to prevent premature leakage of explosive gas. The detonation time of the explosive is recorded as t = 0μs, Figure 5 (a) shows the Mises strain evolution cloud diagram of specimen S1. In the figure, high brightness indicates high strain areas, and low brightness indicates low strain areas. After the explosive is detonated, the circular strain field spreads outward from the charge position as the center. Figure 5 It can be seen that in the early stage of explosive stress transmission, the strain value of the left side of the blasthole is significantly greater than that of the right side of the blasthole. This is mainly because the charge position is close to the left side of the blasthole wall. After the explosive explodes, the explosion stress wave directly acts on the left side of the blasthole, causing the left side of the blasthole to be subjected to greater stress in the early stage. In the later stage of blasting, the forces on the left and right sides of the blasthole tend to be balanced. It can be seen that the charge structure of the blasthole has a significant effect on the evolution of explosive stress. Figure 5 (b) shows the Mises strain evolution cloud diagram of specimen S2. The evolution process of the strain cloud diagram is basically the same as that of specimen S1. In the early stage of the explosive explosion, the strain value on the left side of the blast hole is relatively large. The charge is not in contact with the left and right sides of the blast hole. The cavity between the left side of the charge and the hole wall is small, and the cavity between the right side of the charge and the hole wall is large. Figure 5 (c) shows the Mises strain evolution cloud diagram of specimen S3. It can be seen that the strain distribution on the left and right sides of the blast hole is relatively uniform. This is because the cavities on the left and right sides of the cartridge are of the same size, making the stress state on both sides of the blast hole basically symmetrically distributed.

[0083] 2. Explosion strain peak analysis

[0084] In order to further study the evolution of explosion strain, Figure 6As shown in the figure, the strain time history curves of relevant measuring points are extracted for analysis. In the figure, 5 measuring points are selected on the left side of the blast hole, namely L1, L2, L3, L4 and L5, the distance between two adjacent measuring points is 10mm, and the distance from L1 to the center of the package is 40mm; similarly, 5 measuring points are also selected on the right side of the blast hole, namely R1, R2, R3, R4 and R5, the distance between two adjacent measuring points is 10mm, and the distance from R1 to the center of the package is also 40mm.

[0085] In specimens S1, S2 and S3, the measuring points L1 and R1 are located on the left and right sides of the blast hole, respectively, and the distances to the center of the charge are equal. For specimen S1, the left side of the charge is close to the wall of the blast hole, and the volume of the cavity on the left side of the charge is 0. For the convenience of subsequent analysis, the measuring points on the left side of the charge are recorded as 0-L1, 0-L2, 0-L3, 0-L4 and 0-L5; the volume of the cavity on the right side of the charge is 4V, and the measuring points on the right side of the charge are recorded as 4V-R1, 4V-R2, 4V-R3, 4V-R4 and 4V-R5. Similarly, for specimen S2, the measuring points on the left side of the charge are recorded as V-L1, V-L2, V-L3, V-L4 and V-L5, and the measuring points on the right side of the charge are recorded as 3V-R1, 3V-R2, 3V-R3, 3V-R4 and 3V-R5. For specimen S3, the volumes of the cavities on the left and right sides of the medicine package are the same, both 2V, and the stress states are consistent. Therefore, only the measuring points on the right side can be selected for analysis. The measuring points on the right side of the medicine package are 2V-R1, 2V-R2, 2V-R3, 2V-R4 and 2V-R5 respectively.

[0086] First, the strain evolution analysis is performed on the measuring points L1 and R1 on the left and right sides of the measuring point. Figure 7The figure shows the strain evolution time history curves of the measuring points L1 and R1 of the three groups of specimens. In the figure, negative strain indicates compression, and positive strain indicates tension. The horizontal x-direction strain component εx and the vertical y-direction strain component εy are the basic strains of the deformation of the measuring points. It can be seen from the figure that the x-direction strain component is mainly compressed, the y-direction strain component is mainly tensile, and the x-direction compressive strain is significantly greater than the y-direction tensile strain. Mises strain is an equivalent strain that can comprehensively reflect the stress state of the measuring point. The strain time history of the relevant measuring points shows a double-peak evolution feature, which is more significant for the y-direction strain and Mises strain, which is significantly different from the strain evolution law of coupled charge and uncoupled charge blasting. The first strain peak of the same type at different measuring points is basically obtained at the same time, but the corresponding time of the second strain peak is significantly different. The stress wave generated by the explosion of the explosive acts on the wall of the blasthole, causing the strain of the relevant measuring points to quickly reach the first strain peak. After the explosion of the explosive, high-pressure explosive gas will be generated. The explosive gas compresses the cavity of the blast hole. The explosive gas and the compressed cavity gas impact the blast hole wall again, which stimulates the stress wave in the specimen again and acts on the measuring point to produce a second peak. The time for the explosive gas to compress the cavity gas is relatively long, which distinguishes its effect from the effect of the previous explosion stress wave in terms of time scale, and realizes the separation of the explosion stress wave and the effect of the explosive gas from the experimental level. In addition, it can be found that the second stress wave excited by the expansion of the explosive gas has a larger pulse width and a longer duration, which is conducive to the expansion of the explosion crack.

[0087] The rupture and crack propagation of the specimen under the blast load are mainly affected by tensile stress. For the measuring points on the left and right sides of the blast hole, the x direction is mainly compressed, and the y direction is mainly tensile. Therefore, the y-direction strain component εy of the measuring points L1 or R1 of the above three groups of specimens is mainly compared and analyzed. Figure 8The figure shows the variation curve of the strain peak value in the y direction with the cavity volume. The first strain peak value gradually decreases with the increase of the cavity volume, while the second strain peak value shows a trend of increasing first and then decreasing with the increase of the cavity volume. The first strain peak value is obtained when the cavity volume is 0, which is 2181με; the second strain peak value is obtained when the cavity volume is 3V, which is 2973με. When the cavity volume is small (0 or V), the first strain peak value is significantly larger than the second strain peak value, and the effect of the explosion stress wave is the main one; when the cavity volume is large (≥2V), the first strain peak value is obviously smaller than the second strain peak value, and the effect of the explosion gas occupies a dominant position. In general, with the increase of the cavity volume, in terms of the force on the measuring point, the effect of the explosion stress wave gradually weakens, while the effect of the explosion gas gradually increases. In addition, an excessively large cavity volume will not only reduce the effect of the explosion stress wave, but also inhibit the effect of the explosion gas. It can be seen that a reasonable cavity volume can adjust the spatiotemporal effect of the explosion stress wave and the explosion gas, control the force characteristics of the exploded medium, and thus achieve a better blasting effect. To a certain extent, this is also the mechanism basis for regulating the blasting effect by uncoupled charge blasting.

[0088] In order to further explore the strain peak attenuation law under the action of explosion stress wave and explosion gas, the y-direction strain peak εy,m of the measuring points on the left and right sides of the cavity was measured and fitted to obtain Fig. 9 The attenuation curve shown in the figure shows that the attenuation of the explosion strain peak is nonlinear. Under the action of the explosion load, the attenuation of the strain peak of the measuring point satisfies the following formula.

[0089] ε y,m =a / s -n

[0090] Where: ε y,m is the strain peak value in the y direction; a is the proportional coefficient; s is the distance from the measuring point to the center of the medicine package; n is the strain attenuation exponent.

[0091] The strain decay index n characterizes the strain decay rate of the measuring point. Fig. 9 The strain peak fitting results are shown in Table 1 to obtain the strain attenuation index statistics of the measuring points on one side of the cavity with different volumes. It can be seen from the table that the attenuation index of the second strain peak is significantly greater than the attenuation index of the first strain peak, indicating that the attenuation of the second strain peak caused by the expansion and compression of the explosive gas is faster.

[0092] Table 1 Statistics of strain attenuation index at measuring points on one side of cavities with different volumes

[0093]

[0094] 3. Explosion Crack Analysis

[0095] In order to further explore the distribution characteristics of explosion cracks under the action of explosion stress wave and explosion gas, a blasting model experiment was carried out with organic glass as the experimental material. The crack distribution state around the blast hole after the explosive was detonated is shown in the figure below. Fig.10 As shown in the figure. Under the action of the explosion load, stress concentration effects will occur at the four corners of the blast hole and explosive cracks will be formed, which are recorded as crack A. In addition, in order to study the crack propagation behavior on the left and right sides of the blast hole, a prefabricated crack is prefabricated on the left and right sides of the blast hole, respectively, which is recorded as crack B. Crack B mainly starts and propagates under the action of the stress component in the y direction.

[0096] Similar to the above-mentioned explosion strain study, three groups of experiments were also carried out for the explosion crack analysis in this section, with the explosive charges located at different positions in the blast hole. Fig.11 The distribution of cracks around the blast hole after the three groups of specimens are shown in Table 2. It can be found that when the explosive bag is located at different positions in the blast hole, the distribution of the blast cracks shows significant differences. The stress state of cracks A1 and A2 under the blast load is consistent, and the expansion path and length of cracks A1 and A2 are basically the same. The length of the blast cracks at the measuring points on one side of the cavity of different volumes of the three groups of specimens is statistically shown in Table 2, and further plotted to obtain Fig.12 The curve of the length of the explosion crack changing with the cavity volume is shown in the figure. The formation of cracks A1 and A2 is mainly caused by the stress concentration effect. With the increase of the cavity volume, the peak value of the explosion stress wave is effectively reduced. At the same time, the expansion space of the explosion gas increases and the action time is prolonged, which avoids the excessive crushing of the medium around the blasthole, and provides more lasting power support for the expansion of cracks A1 and A2, so that the extension length of cracks A1 and A2 gradually increases. The expansion power of crack B is the tensile stress component in the y direction. According to the strain analysis results in the previous article, there are two peaks of tensile stress in the y direction. The first peak is caused by the explosion stress wave, and the second peak is formed by the explosion gas. The first peak decreases rapidly with the increase of the cavity volume, while the second peak increases first and then decreases with the increase of the cavity volume. The second peak caused by the explosion gas is the main feature of the relevant measuring point, which determines that the length of crack B increases first and then decreases with the increase of the cavity volume.

[0097] Table 2 Statistics of explosion crack lengths at measuring points on one side of cavities with different volumes

[0098]

[0099] The study of the effects of explosion stress waves and explosion gas has always been an important part of the basic theory of rock blasting. The embodiment of the present invention proposes an evaluation method for separating the time-space effects of explosion stress waves and explosion gas, realizes the quantitative study of the effects of explosion stress waves and explosion gas, and draws the following conclusions:

[0100] (1) By changing the charge structure of the blasthole and setting a cavity between the charge bag and the hole wall, the temporal and spatial characteristics of the explosive gas can be controlled, and the "double peak" evolution law of the explosion strain can be obtained. The first peak is generated by the explosion stress wave, and the second peak is caused by the explosion gas, realizing the separation study of the explosion stress wave and the explosion gas effect;

[0101] (2) The position of the explosive charge has a significant effect on the evolution of explosion strain. As the volume of the cavity increases, the first peak value of the stress component in the y direction gradually decreases, while the second peak value shows a change pattern of first increasing and then decreasing, which represents the different influence mechanisms of the cavity on the explosion stress wave and the explosive gas; in addition, the strain caused by the explosive gas decays more rapidly;

[0102] (3) The position of the explosive charge has a significant effect on the expansion of explosive cracks. As the volume of the cavity increases, the pressure in the hole gradually balances, and the crack extension length caused by stress concentration at the four corners of the blasthole gradually increases, while the crack extension length controlled by the stress component in the y direction shows a trend of first increasing and then decreasing. It can be seen that by reasonably controlling the position of the explosive charge and the volume of the cavity, the spatiotemporal effect of the explosive stress wave and the explosive gas can be fully utilized to achieve controllable rock crushing.

[0103] Embodiment 3

[0104] This embodiment provides a rock blasting method based on the evaluation conclusions obtained in the above embodiments, including step 201 and step 202.

[0105] Step 201, placing explosives in a blast hole, wherein there is a cavity between the explosives and the blast hole wall, and the size of the cavity is set according to the requirements for the blasting effect.

[0106] Among them, the blasting effect is related to the stress characteristics of the rock, the stress characteristics of the rock are controlled by the explosion stress wave and the rock-breaking effect of the explosive gas, and the explosion stress wave and the rock-breaking effect of the explosive gas are related to the size of the cavity.

[0107] Exemplarily, the explosion stress wave and the rock-breaking effect of the blasting gas are associated with the size of the cavity, including at least one of the following situations:

[0108] As the volume of the cavity increases, the rock-breaking effect of the explosion stress wave gradually weakens, and the effect of the explosion gas on rock stress gradually increases; when the cavity volume reaches a preset threshold, the rock-breaking effect of the explosion stress wave is reduced, and the rock-breaking effect of the explosion gas is suppressed;

[0109] With the increase of cavity volume, the rock crack extension length caused by stress concentration gradually increases, while the rock crack extension length controlled by the vertical stress component first increases and then decreases.

[0110] Step 202: Using the explosion effect of the explosive in the blast hole to apply load to the rock, so as to destroy the rock.

[0111] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0112] In the embodiments of the present invention, the term "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent three situations: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0113] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0114] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A quantitative evaluation method for the rock-breaking effect of explosion stress wave and explosion gas, characterized in that: The method includes: Setting multiple relative position relationships between the explosive and the blast hole, where the explosive is located inside the blast hole and there is a cavity between the explosive and the blast hole wall, and the cavity volume between the explosive and the blast hole wall in the direction of the explosive to the measured position of the rock is different under different relative position relationships; For each of the relative position relationships: placing the explosive at the corresponding position in the blast hole, and using the explosion effect of the explosive in the blast hole to apply a load to the rock to break the rock; Based on the stress conditions and / or failure conditions of the measured position of the rock during the rock failure process under multiple relative position relationships, quantitatively evaluating the rock-breaking effect of the explosion stress wave and the explosion-generated gas.

2. The method according to claim 1, characterized in that: The multiple relative position relationships between the explosive and the blast hole include: The first relative position relationship is that the direct contact area between the explosive charge and the blast hole wall is the first area S1, and the cavity volume between the explosive and the blast hole wall in the direction of the explosive to the measured position of the rock is the first volume V1; The second relative position relationship is that the direct contact area between the explosive charge and the blast hole wall is the second area S2, and the cavity volume between the explosive and the blast hole wall in the direction of the explosive to the measured position of the rock is the second volume V2; The nth relative position relationship is that the direct contact area between the explosive charge and the blast hole wall is the second area S2, and the cavity volume between the explosive and the blast hole wall in the direction of the explosive to the measured position of the rock is the nth volume Vn; Wherein, S1 > S2, V1 < V2, Vn - 1 < Vn, and n takes values in sequence as 3, 4... until N, and the N is the total number of types of the multiple relative position relationships between the explosive and the blast hole.

3. The method according to claim 2, characterized in that The shapes of both the explosive charge and the blast hole are prisms, and they only differ in the edge lengths; Placing the bottom surface of the explosive charge against the bottom surface of the blast hole and placing it in the blast hole, and relatively moving along the edge direction in the blast hole to obtain multiple relative position relationships between the explosive and the blast hole.

4. The method according to claim 2, characterized in that: The shapes of both the explosive charge and the blast hole are cylinders, and they only differ in the heights; Placing the bottom surface of the explosive charge against the bottom surface of the blast hole and placing it in the blast hole, and relatively moving along the height direction in the blast hole to obtain multiple relative position relationships between the explosive and the blast hole.

5. The method according to claim 3, characterized in that: The prism is a cuboid; the blasthole is divided into M equal parts along the edge direction, M is greater than or equal to N; the edge length of the explosive charge is equal to the edge length of the blasthole ; No. i The relative position relationship is: the explosive charge is located at the length of the blast hole to Where .

6. The method according to claim 5, characterized in that When M is an even number, N is equal to ; When M is an odd number, N is equal to .

7. The method according to claim 1, characterized in that Quantitatively evaluating the rock-breaking effect of the explosion stress wave and the explosion-generated gas based on the stress conditions and / or failure conditions of the rock during the rock failure process under multiple relative position relationships includes: Based on the change in the stress magnitude and stress distribution of the rock over time during the rock failure process under multiple relative position relationships: Conducting an explosion strain evolution analysis to quantitatively evaluate the separation of the rock-breaking effects of the explosion stress wave and the explosion-generated gas; and / or Conducting an explosion strain peak analysis to quantitatively evaluate the influence of multiple relative position relationships on the rock-breaking effects of the explosion stress wave and the explosion-generated gas; and / or Conducting an explosion crack analysis to quantitatively evaluate the influence of multiple relative position relationships on the explosion crack propagation.

8. The method according to claim 1, characterized in that The explosive is lead azide; the rock is replaced by polycarbonate material or plexiglass material.

9. A rock blasting method, characterized in that: The method includes: Placing the explosive in the blast hole, where there is a cavity between the explosive and the blast hole wall, and the size of the cavity is set according to the requirements for the blasting effect; Using the explosion effect of the explosive in the blast hole to apply a load to the rock to break the rock; Among them, the blasting effect is related to the stress characteristics of the rock, which is controlled by the explosion stress wave and the rock-breaking effect of the blasting gas, which is related to the size of the cavity; The explosion stress wave and the rock-breaking effect of the blast gas are related to the size of the cavity, including at least one of the following situations: As the volume of the cavity increases, the rock-breaking effect of the explosion stress wave gradually weakens, and the effect of the explosion gas on rock stress gradually increases; when the cavity volume reaches a preset threshold, the rock-breaking effect of the explosion stress wave is reduced, and the rock-breaking effect of the explosion gas is suppressed; With the increase of cavity volume, the rock crack extension length caused by stress concentration gradually increases, while the rock crack extension length controlled by the vertical stress component first increases and then decreases.

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