Detonating cord-free smooth blasting method for soft rock roadway of coal mine

Abstract

The invention provides a detonating cord-free smooth blasting method for a soft rock roadway of a coal mine, and belongs to the field of smooth blasting of soft rock roads.The method comprises the steps that half-wall PVC pipe pieces are prepared and used for shaped charge directional fracture control blasting of roadways and tunnels; calculating the interval charging distance of the cartridges in the blast hole in combination with the explosive sympathetic detonation theory and the actual engineering condition; based on the interval charging distance, a cartridge, a water bag, a detonator and a half-wall PVC pipe piece are combined into a detonating cord-free interval charging strip-shaped cartridge bag; the half-wall PVC pipe piece of the detonating cord-free interval charging strip-shaped cartridge bag is attached to surrounding rock and placed into a peripheral hole to implement smooth blasting. According to the detonating cord-free interval charging structure for smooth blasting of the soft rock roadway, the smooth blasting quality of the soft broken surrounding rock is improved, the half-hole mark rate is increased, and the over-excavation and under-excavation of the surrounding rock are controlled.

Description

Technical Field

[0001] The invention relates to the field of soft rock tunnel smooth surface blasting, in particular to a detonating cord-free coal mine soft rock tunnel smooth surface blasting method. Background Art

[0002] There are two main charging structures for traditional smooth blasting. One is to use common explosive rolls and detonating cords for intermittent charging; the other is to use special explosive rolls for continuous charging. The charging method is to use bamboo strips to fix or gun sticks to mark. This traditional smooth blasting charging process is complicated, it is difficult to accurately control the position and spacing of the rolls, and the cost of special explosives and detonating cords is high. Therefore, the use of a new type of smooth blasting charging structure without detonating cord is of great significance for simplifying the process, improving construction efficiency and saving blasting costs. Secondly, in the research on energy-gathering directional fracture control technology, the slit charge technology is relatively widely used, but due to the complex and different on-site working conditions, such as the difficulty of charging in soft rock tunnels due to the rough surface of the blasthole, the problem of not being able to smoothly pass into the blasthole, makes the promotion and on-site use of slit shaped charge packages have some problems. At the same time, after the excavation and blasting of soft rock tunnels, the dust volume and mass are large, causing serious air pollution in the cave, which will endanger human health in the long run. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a method for smooth blasting of soft rock tunnels in coal mines without detonating cords. The method utilizes the principle of explosive sympathetic detonation to realize the intermittent charging of charge rolls while avoiding the use of detonating cords. Combining the shaped charge structure with the water pressure blasting technology, a half-wall PVC pipe is used as the shaped charge medium. While retaining the directional fracture effect of the shaped charge, it is convenient for the loading and positioning of the explosives. The spacing between the explosives is controllable, so that the blasting effect of the explosives in the hole is uniform. Secondly, a water bag is used to block the blasthole. Under the action of the explosive expansion gas, the water medium can make the rock more evenly broken, and can also play a role in atomizing and reducing dust during the blasting process, reducing the flying dust pollution in the working environment. The present invention can effectively reduce the blasting cost, control the section forming, reduce the over-excavation and under-excavation phenomenon, and improve the quality and effect of smooth blasting. Specifically, it includes:

[0004] A detonating cord-free smooth blasting method for soft rock tunnels in coal mines, comprising:

[0005] S1. Prepare half-wall PVC pipe segments, wherein the half-wall PVC pipe segments are used for blasting in lanes and tunnels, and the half-wall PVC pipe segments are used to fix the explosive rolls and the blasting special water bags;

[0006] S2. Calculate the interval charging distance of the charge rolls in the blast hole by combining the explosive detonation theory with the actual engineering conditions;

[0007] S3. Based on the interval charging distance, the medicine roll, water bag, detonator and half-wall PVC pipe segment are combined into a detonating cord-free interval charging strip package;

[0008] S4, placing the half-wall PVC pipe segments of the detonating cord-free spaced charge strip-shaped charges close to the surrounding rock and placing them into the peripheral holes for smooth blasting.

[0009] Optionally, the preparation of the half-wall PVC pipe sheet in S1 includes:

[0010] Determine the outer diameter of the PVC pipe segment as d 外 , d 外 ≤ Peripheral hole diameter, d 外 1mm to 2mm smaller than the peripheral hole diameter;

[0011] Determine the inner diameter of the PVC pipe segment as d 内 , d 内 ≥Diameter of medicine roll, d 内 1mm to 2mm larger than the diameter of the medicine roll;

[0012] Use a cutting machine to cut the PVC pipe piece in half to get a half-wall PVC pipe.

[0013] Optionally, the calculation of the interval charging distance of the charge rolls in the blasthole by combining the explosive sympathetic detonation theory with actual engineering conditions in S2 includes:

[0014] S201, measuring the explosive detonation distance under free field conditions, and solving the shock wave pressure of the explosive at the detonation distance by using the shock wave pressure calculation formula under unconstrained conditions, wherein the shock wave pressure of the explosive at the detonation distance is the critical detonation pressure of the explosive;

[0015] S202, calculating the explosion shock wave pressure on the blast hole when the air gap is uncoupled with the charge, and obtaining the pressure on the blast hole wall;

[0016] S203, based on the pressure on the blasthole wall and the critical detonation pressure of the explosive, obtaining the maximum detonation distance of the explosive under the blasthole constraint condition;

[0017] S204. In combination with the actual engineering background, the length of the blasthole, the diameter of the blasthole, the number of charge rolls in the blasthole and the charge coefficient are considered to obtain the interval charging distance of the charge rolls in the blasthole that meets all the constraints.

[0018] Optionally, the explosive detonation distance is measured under free field conditions in S201, and the shock wave pressure of the explosive at the detonation distance is solved by the shock wave pressure calculation formula under unconstrained conditions, including formula (1):

[0019] P free =ΔP+P air ; (1)

[0020] Among them, P free is the critical detonation pressure of the explosive, in MPa;

[0021] ΔP is the peak overpressure of the shock wave, in MPa;

[0022] P air is the atmospheric pressure, take 0.1MPa;

[0023] Where ΔP follows formula (2):

[0024]

[0025] m is the mass of the spherical charge, in kg;

[0026] x is the distance from the explosion center in meters.

[0027] Optionally, the calculation of the explosion shock wave pressure on the blast hole when the air gap is not coupled with the charge in S202 to obtain the pressure on the blast hole wall includes formula (3):

[0028]

[0029] Among them, P hole is the pressure on the blasthole wall, in Pa;

[0030] n is the pressure increase coefficient when the detonation gas collides with the hole wall, n = 8 ~ 11;

[0031] P vp is the explosion gas pressure, in Pa;

[0032] P K is the critical pressure of the explosive, in MPa;

[0033] m1 is the detonation pressure correction coefficient, which is taken as 1.15;

[0034] P w is the detonation pressure of explosive, in Pa;

[0035] K d is the radial uncoupling coefficient;

[0036] K l is the axial uncoupling coefficient.

[0037] Optionally, the maximum detonation distance of the explosive under the blasthole constraint condition is obtained based on the pressure on the blasthole wall and the critical detonation pressure of the explosive in S203, which includes formula (4):

[0038]

[0039] Among them, L xb is the maximum detonation distance of explosives under the condition of blasthole constraints, in cm;

[0040] Lair is the sum of air intervals, in cm;

[0041] L e It is the length of the medicine roll in cm.

[0042] Optionally, the S204 is combined with the actual engineering background, taking into account the blasthole length, blasthole diameter, number of charge rolls in the blasthole and charge coefficient, to obtain the interval charge distance of the charge rolls in the blasthole that meets all the constraints, including formula (5):

[0043]

[0044] Among them, L e Indicates the length of the medicine roll in cm;

[0045] x is the number of charge rolls in the blast hole;

[0046] L b Indicates the interval charging distance, in cm;

[0047] L1 represents the blockage length in cm;

[0048] L represents the length of the blasthole, in cm;

[0049] φ is the diameter of the blasthole, in mm;

[0050] M represents the charge coefficient of the blast hole.

[0051] Optionally, the step of S3 combining the medicine roll, water bag, detonator and half-wall PVC tube piece into a detonating cord-free interval charge strip package based on the interval charge distance comprises:

[0052] S301, preparing a water bag by a KPS-60 water bag filling and sealing machine, wherein the diameter of the water bag is equal to the diameter of the PVC pipe, and the length of the water bag is set according to demand;

[0053] The cannon mud was prepared by a PNJ-AB160 cannon mud machine, wherein the mass ratio of loess, sand and gravel to water in the cannon mud was: loess: sand and gravel: water = 0.75:0.15:0.2;

[0054] S302, select the third-level coal mine to use emulsion explosives as explosives:

[0055] Fix a medicine roll at the bottom of the half-wall PVC pipe segment as the second medicine package;

[0056] From the bottom of the half-wall PVC tube to the top, the distance from the end of the second drug package to be delivered is L b At the place, fix a medicine roll as the first medicine package to be issued, L b ≤L xb ;

[0057] From the bottom to the top of the half-wall PVC tube, the distance from the end of the first drug package to be delivered is L b At the place, fix a medicine roll as the main medicine package, L b ≤L xb ;

[0058] Fully immerse the detonator into the head of the main charge;

[0059] S303, filling the water bag at the front end of the main explosive bag to obtain a strip-shaped explosive bag with interval charge without detonating cord; wherein the filling length of the water bag is L2, wherein L2 = water bag length × number of water bags.

[0060] Optionally, the step S4 of placing the half-wall PVC pipe segments of the detonating cord-free interval charge strip-shaped charge packages in contact with surrounding rocks and placing them in peripheral holes for smooth blasting includes:

[0061] The half-wall PVC pipe segment of the assembled detonating cord-free spaced charge strip package is fitted into the surrounding rock and placed in the blasthole, and the prepared blasthole mud is backfilled to block the hole mouth, and the blocking length is L1.

[0062] Compared with the prior art, the above technical solution has at least the following beneficial effects:

[0063] By using the principle of explosive sympathetic detonation, the soft rock tunnel smooth blasting without detonating cord interval charging structure is realized; combined with the shaped charge structure, half-wall PVC pipe is used as the shaped medium, which is convenient for loading and positioning of explosives while retaining the shaped directional fracture effect. The interval distance of explosives is controllable, so that the blasting effect of explosives in the hole is uniform. The smooth blasting quality and half-hole mark rate of soft and broken surrounding rock are improved, and the over-excavation and under-excavation of surrounding rock are reduced. The design method of the charge structure has simple parameter calculation and convenient operation. Good smooth blasting effect is obtained in engineering application. It has important significance and application value for realizing smooth blasting of soft and broken surrounding rock in tunnel or tunnel blasting engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0065] Figure 1 It is the diagram of the charge structure of the blast hole;

[0066] Figure 2 This is a cross-sectional view of the charge structure;

[0067] Figure 3 Arrange three views of blastholes for excavation sections;

[0068] Figure 4 This is the diagram of the charge structure of the blasthole at the test site;

[0069] Figure 5 This is a schematic diagram of the half hole mark after the explosion. DETAILED DESCRIPTION

[0070] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment 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.

[0071] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one", "one" or "the" do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0072] It should be noted that the terms "up", "down", "left", "right", "front" and "back" used in the present invention are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0073] There are two main charging structures for traditional smooth blasting. One is to use common explosive rolls and detonating cords for intermittent charging; the other is to use special explosive rolls for continuous charging. The charging method is to use bamboo strips for fixing or sticks for marking. This traditional smooth blasting charging process is complicated, it is difficult to accurately control the position and spacing of the rolls, and the cost of special explosives and detonating cords is high. Secondly, in the research on the control technology of directional fracture of concentrated energy, the slit charge technology is relatively widely used, but due to the complex and different working conditions on site, such as the difficulty of charging in soft rock tunnels due to the rough surface of the blasthole, the problem of not being able to smoothly pass into the blasthole, which makes the promotion and on-site use of slit concentrated charge packages have some problems.

[0074] This patent proposes a new method of smooth surface blasting without detonating cord and shaped charge based on the principle of explosive sympathetic detonation, which solves the problems of high cost and multiple construction processes caused by the use of detonating cord in traditional smooth surface blasting. At the same time, on the basis of the slit charge, the PVC tube is cut axially and the charge is fixed in the half-wall PVC tube by connecting with tape, which is convenient for explosive loading and positioning, and the distance between the explosives can be controlled, so that the blasting effect of the explosives in the hole is uniform. This charge structure has the function of protecting the surrounding rock while retaining the directional fracture effect of shaped charge, which is of great significance and application value for realizing smooth surface blasting in soft rock tunnels or lanes. The specific plan is as follows:

[0075] like Figures 1 to 5 As shown, a method for smooth blasting of soft rock tunnels in coal mines without detonating cord comprises:

[0076] S1. Prepare half-wall PVC pipe segments, wherein the half-wall PVC pipe segments are used for blasting in lanes and tunnels, and the half-wall PVC pipe segments are used to fix the explosive rolls and the blasting special water bags;

[0077] Determine the outer diameter of the PVC pipe segment as dout, dout≤the diameter of the peripheral holes, and dout is 1mm to 2mm smaller than the diameter of the peripheral holes;

[0078] Determine the inner diameter of the PVC tube segment as dinner, dinner ≥ the diameter of the drug roll, and dinner is 1mm to 2mm larger than the diameter of the drug roll;

[0079] Use a cutting machine to cut the PVC pipe piece in half to get a half-wall PVC pipe.

[0080] S2. Calculate the interval charging distance of the charge rolls in the blasthole by combining the explosive detonation theory with the actual engineering conditions; specifically including:

[0081] S201, measuring the explosive detonation distance under free field conditions, and solving the shock wave pressure of the explosive at the detonation distance by using the shock wave pressure calculation formula under unconstrained conditions, wherein the shock wave pressure of the explosive at the detonation distance is the critical detonation pressure of the explosive;

[0082] The specific formula is formula (1):

[0083] P free =ΔP+P air ; (1)

[0084] Among them, P free is the critical detonation pressure of the explosive, in MPa;

[0085] ΔP is the peak overpressure of the shock wave, in MPa;

[0086] P air is the atmospheric pressure, take 0.1MPa;

[0087] Where ΔP follows formula (2):

[0088]

[0089] m is the mass of the spherical charge, in kg;

[0090] x is the distance from the explosion center in meters.

[0091] S202, calculating the explosion shock wave pressure on the blast hole when the air gap is uncoupled with the charge, and obtaining the pressure on the blast hole wall;

[0092] The specific formula includes formula (3):

[0093]

[0094] Among them, P hole is the pressure on the blasthole wall, in Pa;

[0095] n is the pressure increase coefficient when the detonation gas collides with the hole wall, n = 8 ~ 11;

[0096] P vp is the explosion gas pressure, in Pa;

[0097] P K is the critical pressure of the explosive, in MPa;

[0098] m1 is the detonation pressure correction coefficient, which is taken as 1.15;

[0099] P w is the detonation pressure of explosive, in Pa;

[0100] K d is the radial uncoupling coefficient;

[0101] K l is the axial uncoupling coefficient.

[0102] S203, based on the pressure on the blasthole wall and the critical detonation pressure of the explosive, obtain the maximum detonation distance of the explosive under the blasthole constraint condition.

[0103] The specific formula includes formula (4):

[0104]

[0105] Among them, L xb is the maximum detonation distance of explosives under the condition of blasthole constraints, in cm;

[0106] L air is the sum of air intervals, in cm;

[0107] Le It is the length of the medicine roll in cm.

[0108] 3. S204. Combined with the actual engineering background, considering the length of the blasthole, the diameter of the blasthole, the number of charge rolls in the blasthole and the charge coefficient, the interval charge distance of the charge rolls in the blasthole that meets all the constraints is obtained, including formula (5):

[0109]

[0110] Among them, L e Indicates the length of the medicine roll in cm;

[0111] x is the number of charge rolls in the blast hole;

[0112] L b Indicates the interval charging distance, in cm;

[0113] L1 represents the blockage length in cm;

[0114] L represents the length of the blasthole, in cm;

[0115] φ is the diameter of the blasthole, in mm;

[0116] M represents the charge coefficient of the blast hole.

[0117] S3. Based on the interval charging distance, the medicine roll, water bag, detonator and half-wall PVC pipe piece are combined into a detonating cord-free interval charging strip package:

[0118] S301, preparing a water bag by a KPS-60 water bag filling and sealing machine, wherein the diameter of the water bag is equal to the diameter of the PVC pipe, and the length of the water bag is set according to demand;

[0119] The cannon mud was prepared by a PNJ-AB160 cannon mud machine, wherein the mass ratio of loess, sand and gravel to water in the cannon mud was: loess: sand and gravel: water = 0.75:0.15:0.2;

[0120] S302, select the third-level coal mine to use emulsion explosives as explosives:

[0121] Fix a medicine roll at the bottom of the half-wall PVC pipe segment as the second medicine package;

[0122] From the bottom of the half-wall PVC tube to the top, the distance from the end of the second drug package to be delivered is L b At the place, fix a medicine roll as the first medicine package to be issued, L b ≤L xb ;

[0123] From the bottom to the top of the half-wall PVC tube, the distance from the end of the first drug package to be delivered is L bAt the place, fix a medicine roll as the main medicine package, L b ≤L xb ;

[0124] Fully immerse the detonator into the head of the main charge;

[0125] S303, filling the water bag at the front end of the main explosive bag to obtain a strip-shaped explosive bag with interval charge without detonating cord; wherein the filling length of the water bag is L2, wherein L2 = water bag length × number of water bags.

[0126] S4, placing the half-wall PVC pipe segments of the detonating cord-free interval charge strip-shaped charge packs close to the surrounding rock and placing them into the surrounding holes for smooth blasting:

[0127] The half-wall PVC pipe segment of the assembled detonating cord-free spaced charge strip package is fitted into the surrounding rock and placed in the blasthole, and the prepared blasthole mud is backfilled to block the hole mouth, and the blocking length is L1.

[0128] The present invention relies on the excavation project of the water inlet tunnel at the bottom of the water tank in the 22nd mining area of ​​a certain mining area. The maximum thickness of the coal seam in the water tank tunnel at the bottom of the 22nd mining area is 3.5m, the hardness is f=3.5, the coal seam joints are relatively developed, and there are no faults, karst collapse columns and other geological structures. The cross-sectional dimensions of the excavation of the bottom water tank in the 22nd mining area are 4500mm (width) × 3600mm (height), and the designed length is 31.56m. The cross-sectional excavation adopts wedge-shaped grooving, forward charging, batch charging, and detonation in batches. The three-view drawing of the cross-sectional blasthole arrangement is as follows Figure 3 As shown. The peripheral blastholes are 2m deep and 40mm in diameter. If the traditional smooth blasting method of explosive rolls and detonating cord interval charging is adopted, not only will the charging process be complicated and the detonating cord cost be high, but also over-excavation and under-excavation may occur. Without changing the number and arrangement of blastholes, the present invention utilizes the principle of explosive sympathetic detonation to optimize the charging structure of the cross-section peripheral holes, thereby realizing smooth blasting of soft rock tunnels without the detonating cord interval charging structure and reducing the blasting cost. At the same time, the shaped charge structure is utilized to achieve the purpose of increasing the semi-hole mark rate and blasthole utilization rate, reducing over-excavation and under-excavation, and improving the smooth blasting effect. The specific implementation method includes the following steps:

[0129] Energy-gathering PVC pipe segments for making fixed charge coils and water bags for tunnel (lane) blasting.

[0130] Since the peripheral holes are 2m deep, 40mm in diameter, and the drug coil diameter is 32cm, a PVC pipe with an outer diameter of 38mm, an inner diameter of 34mm, and a length of 2m is selected as the energy-gathering medium. The PVC pipe is cut in half with a cutting machine to obtain a half-wall PVC pipe used to fix the drug coil and the water bag for tunnel (lane) blasting.

[0131] The detonation distance of emulsion explosives is calculated based on detonation theory.

[0132] According to the theory of explosion shock wave pressure detonation, when the shock wave pressure generated by the explosion of the main charge is greater than or equal to the critical detonation pressure of the explosive, the secondary charge will be detonated. Therefore, to calculate the detonation distance of the explosive in the blast hole, it is necessary to first determine the critical pressure of the explosive detonation, and then combine the calculation formula of the shock wave pressure of the explosive in the blast hole, and make it equal to the critical pressure of the explosive detonation, and then the calculation formula of the detonation distance of the explosive under the constraint of the blast hole can be obtained. The specific steps are as follows:

[0133] The explosive detonation distance is measured under free field conditions, and the shock wave pressure of the explosive at the detonation distance is solved by the shock wave pressure calculation formula under unconstrained conditions, which is the critical detonation pressure of the explosive.

[0134] Calculate the explosion shock wave pressure on the blast hole when the air gap is not coupled with the charge.

[0135] Let the impact pressure P generated by the main propellant in the blast hole be hole Equal to the critical detonation pressure P of the explosive package being fired free , the detonation distance L of the explosive under the condition of blasthole constraint can be obtained xb .

[0136] Combined with the on-site lithology conditions, charging coefficient, blasthole length and other conditions, calculate the interval charging distance L of the charge rolls in the blasthole that meets all constraints b

[0137] In summary, in order to ensure the successful detonation of the explosive packages, the distance between the explosive packages in the blast hole is L b Should be less than or equal to the detonation distance L under the blast hole constraint condition xb The research background of this patent is soft rock tunnel. The explosive used is the third-level coal mine permitted emulsion explosive (300g*32mm*30cm), the single hole charge is 3 rolls, the charge coefficient is 0.45, the taphole mud is blocked by 50cm, and the maximum sympathetic detonation distance L under the constraint of the blasthole is calculated. xb The distance L between the charge rolls in the blast hole and the charge rolls that meet all the constraints is about 80 to 90 cm. b ≤30cm. Therefore, the distance L between the charges in the blast holes at the construction site is b Designed for 20cm.

[0138] The powder roll, water bag, detonator and half-wall shaped PVC tube are combined into a strip-shaped powder bag with interval loading without detonating cord.

[0139] The holes around the test site are 2m deep and 40mm in diameter. The charge structure is divided into three parts based on the energy-gathering tube segment: explosive filling section, water bag filling section and hole plugging section. Figure 4 The medicine roll and water bag need to be fixed on the PVC pipe sheet. The specific steps are as follows:

[0140] A KPS-60 water bag filling and sealing machine was used to prepare water bags with a diameter of 34 mm and a length of 20 cm, which were used to extend the action range of explosives. A PNJ-AB160 gun mud machine was used to make gun mud with three raw materials, loess, sand and gravel, and water, in a mass ratio of 0.75:0.15:0.2, which was used to plug gun holes.

[0141] The explosive used in this patent is the third-level coal mine permitted emulsion explosive (300g*32mm*30cm), and the explosive rolls are fixed in the half-wall PVC pipe in sequence to form an explosive filling section. The specific fixing order of the explosive rolls is: fix a section of the explosive roll at the bottom of the PVC pipe as the sent explosive package 2; fix a section of the explosive roll 20cm away from the end of the sent explosive package 2 as the sent explosive package 1; fix a section of the explosive roll 20cm away from the end of the sent explosive package 1 as the main explosive package; insert the electronic detonator into the head of the main explosive package and completely immerse it to detonate the main explosive package.

[0142] Fix a 20cm water bag in the half-wall PVC pipe above the explosive filling section to form a water bag filling section. It should be noted that after the water bag is made, avoid long-term storage. Check the quality of the water bag carefully before use and choose a water bag that meets the requirements; after the cannon mud is made, avoid long-term storage and try to choose a cool place for storage.

[0143] Keep the pipe segments close to the surrounding rock and place them into the surrounding holes to carry out smooth blasting.

[0144] The half-wall PVC pipe segment assembled with explosives and water bags is placed in the blasthole in close contact with the surrounding rock, and then the hole is blocked with the prepared blasthole mud. The length of the hole blockage is 50cm.

[0145] This patent has been successfully applied in the excavation project of the water tank water inlet tunnel at the bottom of the 22nd mining area of ​​a certain mine field. The traditional charging structure is changed in the peripheral holes. A new charging structure optimized with PVC energy-gathering tubes and detonating cord-free interval charging is adopted, which can make the half-hole mark rate of the blasthole reach more than 90%, improve the utilization rate of the blasthole, reduce over-excavation and under-excavation, and effectively improve the cross-section forming effect, thereby improving the quality of smooth blasting. Blasting effect such as Figure 5 As shown. The amount of blasting smoke and dust on the working face decreased by 50-70% within 10 minutes after the explosion, and decreased by more than 70% after 20 minutes, effectively improving the working environment of subsequent operations. It not only improved the working environment of workers, but also improved the environmental protection of the construction. Compared with the traditional blasting charge structure, the optimized detonating cord-free interval charge structure has a significant reduction in the blasting vibration peak.

[0146] By using the principle of explosive sympathetic detonation, the soft rock tunnel smooth blasting without detonating cord interval charging structure is realized; at the same time, the shaped charge structure is combined with the hydraulic blasting technology, and the charge roll, water bag, detonator and half-wall shaped PVC pipe segment are combined into a strip charge package without detonating cord interval charging, which improves the smooth blasting quality and half-hole mark rate of soft and broken surrounding rock, and reduces the over-excavation and under-excavation of surrounding rock. The charge structure design method has simple parameter calculation and convenient operation, and obtains good smooth blasting effect in engineering application. It has important significance and application value for realizing smooth blasting of soft and broken surrounding rock in tunnel or tunnel blasting engineering.

[0147] The following points need to be explained:

[0148] (1) The drawings of the embodiments of the present invention only relate to the structures related to the embodiments of the present invention, and other structures may refer to the general design.

[0149] (2) For the sake of clarity, in the drawings used to describe the embodiments of the present invention, the thickness of the layers or regions is exaggerated or reduced, that is, these drawings are not drawn according to the actual scale. It is understood that when an element such as a layer, film, region or substrate is referred to as being "on" or "under" another element, the element may be "directly" "on" or "under" the other element or there may be intermediate elements.

[0150] (3) In the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to obtain new embodiments.

[0151] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for smooth blasting of soft rock tunnels in coal mines without detonating cord, characterized in that: include: S1. Prepare half-wall PVC pipe segments, wherein the half-wall PVC pipe segments are used for blasting in lanes and tunnels, and the half-wall PVC pipe segments are used to fix the explosive rolls and the blasting special water bags; S2. Calculate the interval charging distance of the charge rolls in the blast hole by combining the explosive detonation theory with the actual engineering conditions; S3. Based on the interval charging distance, the medicine roll, water bag, detonator and half-wall PVC pipe segment are combined into a detonating cord-free interval charging strip package; S4, placing the half-wall PVC pipe segments of the detonating cord-free spaced charge strip-shaped charges close to the surrounding rock and placing them into the peripheral holes for smooth blasting.

2. The method for smooth blasting of soft rock tunnels in coal mines without detonating cord according to claim 1, characterized in that: The preparation of the half-wall PVC pipe sheet in S1 comprises: Determine the outer diameter of the PVC pipe segment as d 外 , d 外 ≤ Peripheral hole diameter, d 外 1mm to 2mm smaller than the peripheral hole diameter; Determine the inner diameter of the PVC pipe segment as d 内 , d 内 ≥Diameter of medicine roll, d 内 1mm to 2mm larger than the diameter of the medicine roll; Use a cutting machine to cut the PVC pipe piece in half to get a half-wall PVC pipe.

3. The method for smooth blasting of soft rock tunnels in coal mines without detonating cord according to claim 2, characterized in that: The S2 combines the explosive detonation theory with the actual engineering conditions to calculate the interval charging distance of the charge rolls in the blasthole, including: S201, measuring the explosive detonation distance under free field conditions, and solving the shock wave pressure of the explosive at the detonation distance by using the shock wave pressure calculation formula under unconstrained conditions, wherein the shock wave pressure of the explosive at the detonation distance is the critical detonation pressure of the explosive; S202, calculating the explosion shock wave pressure on the blast hole when the air gap is uncoupled with the charge, and obtaining the pressure on the blast hole wall; S203, based on the pressure on the blasthole wall and the critical detonation pressure of the explosive, obtaining the maximum detonation distance of the explosive under the blasthole constraint condition; S204. In combination with the actual engineering background, the length of the blasthole, the diameter of the blasthole, the number of charge rolls in the blasthole and the charge coefficient are considered to obtain the interval charging distance of the charge rolls in the blasthole that meets all the constraints.

4. The method for smooth blasting of soft rock tunnels in coal mines without detonating cord according to claim 3 is characterized in that: The explosive detonation distance is measured under free field conditions in S201, and the shock wave pressure of the explosive at the detonation distance is solved by the shock wave pressure calculation formula under unconstrained conditions, including formula (1): P free =ΔP+P air ; (1) Among them, P free is the critical detonation pressure of the explosive, in MPa; ΔP is the peak overpressure of the shock wave, in MPa; P air is the atmospheric pressure, take 0.1MPa; Where ΔP follows formula (2): m is the mass of the spherical charge, in kg; x is the distance from the explosion center in meters.

5. The method for smooth blasting of soft rock tunnels in coal mines without detonating cord according to claim 4, characterized in that: The calculation of the explosion shock wave pressure on the blast hole when the air gap is not coupled with the charge in S202, and the pressure on the blast hole wall are obtained by formula (3): Among them, P hole is the pressure on the blasthole wall, in Pa; n is the pressure increase coefficient when the detonation gas collides with the hole wall, n = 8 ~ 11; P vp is the explosion gas pressure, in Pa; P K is the critical pressure of the explosive, in MPa; m1 is the detonation pressure correction coefficient, which is taken as 1.15; P w is the detonation pressure of explosive, in Pa; K d is the radial uncoupling coefficient; K l is the axial uncoupling coefficient.

6. The method for smooth blasting of soft rock tunnels in coal mines without detonating cord according to claim 5, characterized in that: The maximum detonation distance of the explosive under the blasthole constraint condition is obtained based on the pressure on the blasthole wall and the critical detonation pressure of the explosive in S203, including formula (4): Among them, L xb is the maximum detonation distance of explosives under the condition of blasthole constraints, in cm; L air is the sum of air intervals, in cm; L e It is the length of the medicine roll in cm.

7. The method for smooth blasting of soft rock tunnels in coal mines without detonating cord according to claim 6, characterized in that: The S204 is combined with the actual engineering background, taking into account the length of the blasthole, the diameter of the blasthole, the number of charge rolls in the blasthole and the charge coefficient, and the interval charge distance of the charge rolls in the blasthole that meets all the constraints is obtained, including formula (5): Among them, L e Indicates the length of the medicine roll in cm; x is the number of charge rolls in the blast hole; L b Indicates the interval charging distance, in cm; L1 represents the blockage length in cm; L represents the length of the blasthole, in cm; φ is the diameter of the blasthole, in mm; M represents the charge coefficient of the blast hole.

8. The method for smooth blasting of soft rock tunnels in coal mines without detonating cord according to claim 7, characterized in that: The S3 combines the charge roll, water bag, detonator and half-wall PVC tube into a detonating cord-free interval charge strip package based on the interval charge distance, including: S301, preparing a water bag by a KPS-60 water bag filling and sealing machine, wherein the diameter of the water bag is equal to the diameter of the PVC pipe, and the length of the water bag is set according to demand; The cannon mud was prepared by a PNJ-AB160 cannon mud machine, wherein the mass ratio of loess, sand and gravel to water in the cannon mud was: loess: sand and gravel: water = 0.75:0.15:0.2; S302, select the third-level coal mine to use emulsion explosives as explosives: Fix a medicine roll at the bottom of the half-wall PVC pipe segment as the second medicine package; From the bottom of the half-wall PVC tube to the top, the distance from the end of the second drug package to be delivered is L b At the place, fix a medicine roll as the first medicine package to be issued, L b ≤L xb ; From the bottom to the top of the half-wall PVC tube, the distance from the end of the first drug package to be delivered is L b At the place, fix a medicine roll as the main medicine package, L b ≤L xb ; Fully immerse the detonator into the head of the main charge; S303, filling the water bag at the front end of the main explosive bag to obtain a strip-shaped explosive bag with interval charge without detonating cord; wherein the filling length of the water bag is L2, wherein L2 = water bag length × number of water bags.

9. The method for smooth blasting of soft rock tunnels in coal mines without detonating cord according to claim 8, characterized in that: The step S4 of placing the half-wall PVC pipe segments of the detonating cord-free interval charge strip-shaped charge packages in contact with the surrounding rocks and placing them in the peripheral holes for smooth blasting includes: The half-wall PVC pipe segment of the assembled detonating cord-free spaced charge strip package is fitted into the surrounding rock and placed in the blasthole, and the prepared blasthole mud is backfilled to block the hole mouth, and the blocking length is L1.

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