Tunnel face peripheral hole shaped charge blasting device and blasting quality evaluation method

Abstract

The invention discloses a tunnel face peripheral hole shaped charge blasting device and a blasting quality evaluation method, and belongs to the technical field of tunnel engineering blasting construction. The device comprises a three-slit shaped charge pipe (the diameter of a copper pipe is 45 mm, the slit width is 4.5 mm, and the included angle of three slits is 90 degrees) and a special-shaped charge structure (the diameter of a PVC pipe is 40 mm, the PVC pipe is provided with an energy-gathering groove, and the groove angle is 60 degrees), emulsion explosives and a digital electronic detonator are fixed through bamboo chips, a middle slit vertically faces the inner side of an excavation contour line, and multi-directional stress wave superposition control is achieved. After blasting, data are collected based on technologies such as a section laser range finder and a vibration sensor, a multi-dimensional evaluation system containing geometric indexes (the back break distance, the half-hole rate and the section fractal dimension) and safety indexes (the damage PPV value and the surrounding rock quality score) is constructed, an improved AHP-entropy weight combination weighting method is adopted for calculating the weight, and the blasting quality grade is determined through a confidence coefficient rule.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering blasting construction technology, specifically to a shaped charge blasting device for the perimeter holes of a tunnel face and a method for evaluating blasting quality. By optimizing the shaped charge structure, the disturbance to the surrounding rock caused by blasting is reduced, and a multi-dimensional evaluation system is used to achieve a quantitative evaluation of the blasting effect. Background Technology

[0002] Traditional tunnel perimeter blasting primarily employs a double-slit shaped charge structure, a special shaped charge device used in blasting engineering. Its core feature is the presence of two symmetrical slits on the outer shell or shaped charge liner. This design aims to utilize the shaped charge effect (Monroe effect) to highly concentrate and directionally release explosive energy, making it particularly suitable for applications requiring the formation of specific shapes (such as two parallel cracks) or enhanced cutting / fragmentation effects in specific directions.

[0003] However, conventional double-slit shaped charge blasting structures concentrate blasting energy on one side, resulting in significant surrounding rock disturbance, poor forming effect, and low half-hole ratio. Furthermore, existing technologies lack multi-dimensional quantitative evaluation of blasting effects, typically relying on single indicators such as over-excavation rate or half-hole ratio, which fails to comprehensively reflect surrounding rock damage and safety vibration impacts. To address these issues, this invention proposes a shaped charge blasting device for the perimeter holes of a tunnel face and a method for evaluating blasting quality. Summary of the Invention

[0004] The purpose of this invention is to provide a shaped charge blasting device for the perimeter holes of a tunnel face and a method for evaluating blasting quality in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: A shaped charge blasting device for the perimeter holes of a tunnel face includes a slit tube and a shaped charge tube, wherein the slit tube is sleeved on the outside of the shaped charge tube; slits are provided on the left and right sides and the bottom side of the slit tube, and the angle between the bottom slit and the side slits is 90°; an irregularly shaped charge structure is provided inside the shaped charge tube, the irregularly shaped charge structure is filled with emulsion explosive, a detonator is inserted inside the emulsion explosive, and a cap is connected to the top of the shaped charge tube; The shaped charge tubes are fixed to the bamboo strips at intervals, and the shaped charge tubes and bamboo strips are placed inside the slit tube. The left and right sides and the bottom side of the shaped charge tubes are provided with shaped charge grooves, and the shaped charge grooves match the slits on the slit tube.

[0006] Preferably, the slit tube is made of copper tube with a diameter of 45 mm and a thickness of 1.5 mm; the slit width is 4.5 mm.

[0007] Preferably, the shaped charge tube is made of polyvinyl chloride (PVC) pipe with a diameter of 40 mm and a thickness of 1.5 mm; the shaped charge slot is provided with three slots, and the slot opening angle is 60°.

[0008] A method for evaluating the blasting quality of a shaped charge blasting device with peripheral holes at the tunnel face includes the following steps: S1. Place the shaped charge tube of the shaped charge device into the slit tube, and adjust the shaped charge tube so that the shaped charge slot is aligned with the slit of the slit tube one by one. S2. Insert the shaped charge blasting device into the peripheral holes of the tunnel face, and adjust the shaped charge blasting device so that the line connecting the slit holes coincides with the excavation outline, wherein the slit opening in the middle is perpendicular to the excavation outline and points inward. S3. Conduct post-blasting quality evaluation based on the blasting situation, construct a multi-dimensional evaluation system, and calculate the blasting effect by using a combination weighting method and setting a blasting quality confidence level.

[0009] Preferably, the installation of the shaped charge blasting device into the peripheral hole of the tunnel face as described in S2 specifically includes the following: Create engineering cross-sections based on the type and size of the tunnel excavation cross-section, draw the tunnel cross-section outline, and calculate the geometric parameters of the tunnel cross-section outline. The location of the blasting holes and the amount of explosive charge are determined according to the blasting design, and then the shaped charge blasting device is installed into the peripheral holes of the tunnel face.

[0010] Preferably, the evaluation indicators of the multidimensional evaluation system specifically include: the overall maximum under-excavation distance, the average over-excavation distance, the over-excavation rate, the half-hole rate, the cross-sectional fractal dimension, the damage PPV value at 1.5m, the far-field vibration PPV value, and the surrounding rock quality score; the grading thresholds of the above indicators are determined by laser cross-sectional scanning and K-means clustering analysis.

[0011] Preferably, the cross-sectional fractal dimension is calculated and graded by wavelet analysis; the damage PPV value at 1.5m is graded according to the hard rock damage standard.

[0012] Preferably, the calculation of the blasting effect by using a combined weighting method and setting a blasting quality confidence level in step S3 specifically includes the following: The multidimensional evaluation system determines the weights of evaluation indicators by improving the AHP method and the entropy method. Based on the evaluation indicators of the multidimensional evaluation system, a comparison matrix A=[ a ij ] 12×12 The weight vector of the evaluation index is W IAHP The calculation formula is as follows:

[0013] In the formula, , i =1,2,…, n ; Calculate the information entropy of each indicator H j And entropy weight W E The calculation formula is as follows:

[0014]

[0015] In the formula, f ij = , in , Let j be the value of the j-th index of the i-th blasting section; The following can be obtained using the addition combination formula:

[0016] In the formula, k 1, k 2 represents the coefficients of determination for Lagrange optimization; p i , q j These represent the weighting coefficients obtained by the subjective and objective weighting methods, respectively. j =1,2,…, n ; Set the multi-index measurement vector as follows:

[0017] In the formula, μ jk For the measurement of multiple indicators for evaluating the quality of tunnel blasting; j=1,2,…, n Here are the sequence numbers of the evaluation indicators in the multidimensional evaluation system; k=1,2,… p For each assessment level, there is a serial number; The confidence level for the comprehensive evaluation of blasting quality includes: set up λ If ≥0.6 is the confidence level for satisfaction, then:

[0018] In the formula, To ultimately determine the blasting quality level.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention proposes a shaped charge blasting device for the perimeter holes of a tunnel face and a method for evaluating blasting quality. Based on the traditional double-slit charge structure design, an additional slit is added to the side of the slit tube closest to the blasting rock mass, which is conducive to further fragmentation of the blasting rock mass, reduces blasting fragmentation, and establishes a scientific evaluation system. The blasting parameters are dynamically adjusted to reduce damage to the surrounding rock and improve the controllability of blasting quality. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings involved in the embodiments are now briefly described. Obviously, the drawings in the following description are merely illustrative of some embodiments of the present invention. For those skilled in the art, other forms of drawings can be constructed based on these drawings without creative effort.

[0021] Figure 1 This is a diagram of the slit tube device mentioned in Embodiment 1 of the present invention.

[0022] Figure 2 This is a structural diagram of the shaped charge mentioned in Embodiment 1 of the present invention. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0025] Example 1: Please see Figure 1-2 This invention proposes a shaped charge blasting device for the perimeter holes of a tunnel face, comprising a slit tube and a shaped charge tube, wherein the slit tube is sleeved outside the shaped charge tube; slits are provided on the left and right sides and the bottom side of the slit tube, and the angle between the bottom slit and the side slits is 90°; an irregularly shaped charge structure is provided inside the shaped charge tube, the irregularly shaped charge structure is filled with emulsion explosive, a detonator is inserted inside the emulsion explosive, and a cap is connected to the top of the shaped charge tube; The shaped charge tubes are fixed to the bamboo strips at intervals, and the shaped charge tubes and bamboo strips are placed inside the slit tube. The left and right sides and the bottom of the shaped charge tubes are provided with shaped charge grooves, which match the slits on the slit tube.

[0026] The slit tube is made of copper tubing with a diameter of 45 mm and a thickness of 1.5 mm; the slit width is 4.5 mm.

[0027] The shaped charge tube is made of polyvinyl chloride (PVC) pipe with a diameter of 40 mm and a thickness of 1.5 mm; there are three shaped charge slots with an opening angle of 60°.

[0028] Furthermore, a method for evaluating the blasting quality of a shaped charge blasting device with peripheral holes at the tunnel face is proposed, comprising the following steps: S1. Place the shaped charge tube of the shaped charge device into the slit tube, and adjust the shaped charge tube so that the shaped charge slot is aligned with the slit of the slit tube one by one. S2. Create the engineering cross-section according to the type and size of the tunnel excavation section, draw the tunnel cross-section outline, and calculate the geometric parameters of the tunnel cross-section outline; determine the location of the blasting holes and the amount of explosive according to the blasting design, and then install the shaped charge blasting device into the peripheral holes of the tunnel face. Adjust the shaped charge blasting device so that the line connecting the slit holes coincides with the excavation outline, wherein the middle slit opening is perpendicular to the excavation outline and extends inward. S3. Conduct post-blasting quality evaluation based on blasting conditions, and construct a multi-dimensional evaluation system. The evaluation indicators of the multi-dimensional evaluation system specifically include: overall maximum under-excavation distance, average over-excavation distance, over-excavation rate, half-hole rate, cross-sectional fractal dimension, damage PPV value at 1.5m, far-field vibration PPV value, and surrounding rock quality score. The grading thresholds for the above indicators are determined by laser cross-section scanning and K-means clustering analysis. The cross-sectional fractal dimension is calculated and graded by wavelet analysis. The damage PPV value at 1.5m is graded according to the hard rock damage standard. The blasting effect is calculated by using a combined weighted method and setting a confidence level for blasting quality, specifically including the following: The multidimensional evaluation system determines the weights of evaluation indicators by improving the AHP method and the entropy method. Based on the evaluation indicators of the multidimensional evaluation system, a comparison matrix A=[ a ij ] 12×12 The weight vector of the evaluation index is W IAHP The calculation formula is as follows:

[0029] In the formula, , i =1,2,…, n ; Calculate the information entropy of each indicator H j And entropy weight W E The calculation formula is as follows:

[0030]

[0031] In the formula, f ij = , in , Let j be the value of the j-th index of the i-th blasting section; The following can be obtained using the addition combination formula:

[0032] In the formula, k 1, k 2 represents the coefficients of determination for Lagrange optimization; p i , q j These represent the weighting coefficients obtained by the subjective and objective weighting methods, respectively. j =1,2,…, n ; Set the multi-index measurement vector as follows:

[0033] In the formula, μ jk For the measurement of multiple indicators for evaluating the quality of tunnel blasting; j=1,2,…, n Here are the sequence numbers of the evaluation indicators in the multidimensional evaluation system; k=1,2,… p For each assessment level, there is a serial number; The confidence level for the comprehensive evaluation of blasting quality includes: set up λ If ≥0.6 is the confidence level for satisfaction, then:

[0034] In the formula, To ultimately determine the blasting quality level.

[0035] Example 2: An engineering comparative experiment was conducted on the blasting device, with a control group and an experimental group set up. The blasting quality level was evaluated based on the proposed blasting quality evaluation method.

[0036] The control group used a conventional double-slit shaped charge tube (copper tube diameter 45mm, symmetrical double slits, slit width 4.5mm, no bottom slit); the experimental group used the three-slit shaped charge blasting device of the present invention (parameters same as in Example 1). The comparative engineering experiment was conducted under the following conditions: adjacent sections of the same tunnel (surrounding rock grade III, granite), with the same blasting parameters: hole spacing of 0.5m, charge amount of 1.2kg / m, electronic detonator delay of 15ms, and blasting cycles repeated 3 times for each group.

[0037] Data collection and comparison indicators

[0038] The confidence levels of the blasting methods for the control group and the experimental group were calculated based on the blasting quality evaluation method. The blasting quality level of the experimental group was Grade I, with a confidence level λ = 0.87 (>0.6); the blasting quality level of the control group was Grade III, with a confidence level λ = 0.52.

[0039] Experiments show that the three-slit structure of this invention achieves multi-directional superposition of stress waves through the synergistic effect of three slits and three 60° energy-concentrating grooves, which is superior to the traditional double-slit structure. Improved forming effect: Half-hole ratio increased by more than 40%, and over- and under-digging reduced by more than 50%; Enhanced surrounding rock protection: Damage PPV reduced by 46.9%, fracture depth reduced by 50%; Safety risks decreased: far-field vibration PPV decreased by 41.5%, significantly below the safety threshold.

[0040] The constructed multi-dimensional evaluation system (integrating geometric / safety indicators) and confidence rules can quantitatively verify the blasting quality level and provide a basis for dynamically optimizing blasting parameters.

[0041] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A device for tunnel face perimeter hole shaped charge blasting, characterized in that, The application relates to a polyenergic blasting device, which comprises a slit tube and a polyenergic charge tube, the slit tube is sleeved outside the polyenergic charge tube, slits are arranged on the left side, the right side and the bottom side of the slit tube, the angle between the bottom slit and the two side slits is 90 degrees, a special-shaped charge structure is arranged in the polyenergic charge tube, the special-shaped charge structure is filled with emulsion explosive, a detonator is inserted into the emulsion explosive, and a cover is connected to the top end of the polyenergic charge tube. The polyenergic charge tube is fixed on bamboo slices in sequence at intervals, and the polyenergic charge tube is arranged in the slit tube together with the bamboo slices; polyenergic grooves are arranged on the left side, the right side and the bottom side of the polyenergic charge tube, and the polyenergic grooves are matched with the slits on the slit tube.

2. A device for tunnel face perimeter hole shaped charge blasting according to claim 1, characterized in that, The slit tube is made of copper and has a diameter of 45 mm and a tube thickness of 1.5 mm; the slit width is 4.5 mm.

3. A device for tunnel face perimeter hole shaped charge blasting according to claim 1, characterized in that, The polyenergic charge tube is made of polyvinyl chloride (PVC) and has a diameter of 40 mm and a tube thickness of 1.5 mm; three polyenergic grooves are arranged, and the groove opening angle is 60 degrees.

4. A method for evaluating the blasting quality of the device according to any one of claims 1-3, characterized in that, The application further discloses a polyenergic blasting method. S1, the polyenergic charge tube of the polyenergic blasting device is placed in the slit tube, and the polyenergic charge tube is adjusted so that the polyenergic grooves are aligned with the slits of the slit tube one by one; S2, the polyenergic blasting device is arranged in the peripheral hole of the tunnel tunnel face, and the polyenergic blasting device is adjusted so that the slit hole connecting line is coincident with the excavation contour line, wherein the middle slit hole is perpendicular to the excavation contour line and is inward; S3, the blasting quality evaluation is carried out according to the blasting condition, a multi-dimensional evaluation system is constructed, the blasting effect is calculated through the combination weighting method and the setting of the blasting quality confidence.

5. The method of claim 4, wherein The arrangement of the polyenergic blasting device in the peripheral hole of the tunnel tunnel face in S2 specifically includes the following contents: An engineering section is created according to the type and size of the tunnel excavation section, the tunnel section contour line is drawn, and the geometric parameters of the tunnel section contour line are calculated; The position of the blasting hole and the charge amount are determined according to the blasting design, and then the polyenergic blasting device is arranged in the peripheral hole of the tunnel tunnel face.

6. The method of claim 4, wherein The evaluation indexes of the multi-dimensional evaluation system specifically include the overall maximum underbreak distance, the average overbreak distance, the overbreak rate, the half-hole rate, the section fractal dimension, the damage PPV value at 1.5 m, the far-field vibration PPV value and the surrounding rock quality score; the grading threshold values of the above indexes are determined through laser section scanning and K-means clustering analysis.

7. The method of evaluating the quality of an explosive according to claim 6, characterized in that, The section fractal dimension is calculated and graded through wavelet analysis; the damage PPV value at 1.5 m is graded according to the hard rock damage standard.

8. The method of evaluating the quality of an explosive according to claim 7, characterized in that, The blasting effect is calculated through the combination weighting method and the setting of the blasting quality confidence in S3, and the specific contents include the following: The multi-dimensional evaluation system determines the weight of the evaluation index by improving the AHP method and the entropy method, and constructs a comparison matrix A=[ based on the evaluation index of the multi-dimensional evaluation system. a ij ] 12×12 , and the weight vector of the evaluation index is W IAHP , and the calculation formula is: In the formulae, , i = 1, 2,..., n ; Calculate the index information entropy H j and entropy weight W E The calculation formula is: wherein f ij = ; wherein , is the value of the jth index of the ith blast section. The addition combination formula is used to obtain: wherein k 1, k 2 is a Lagrangian optimization determined coefficient; p i , q j respectively represent the weight coefficients obtained by subjective and objective weighting methods, j = 1, 2, …, n ; The multi-index measurement vector is set as: In the formula, The blasting quality comprehensive evaluation confidence is set as: jk is the multiple index measurement of the tunnel blasting quality evaluation; j = 1, 2, …, n is the serial number of the evaluation index of the multi-dimensional evaluation system; k = 1, 2, …, p is the serial number of each evaluation grade; ​ Set ​ ≥ 0.6 is the confidence that the condition is met, then: In the formula, To determine the final quality of the explosion grade.

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