Blasting enhanced gas fracturing pipe and operation method thereof

Abstract

The invention provides a blasting enhancement type gas fracturing pipe and an operation method thereof, the blasting enhancement type gas fracturing pipe comprises a gas fracturing pipe body and a constraint enhancement layer, the gas fracturing pipe body is of a two-layer structure which is sleeved inside and outside, the material strength of the inner layer is higher than a set value, the outer layer and the constraint enhancement layer are integrally arranged, and the space between the inner layer and the outer layer is vacuum; the constraint enhancement layer is formed by weaving a material with certain strength and is provided with a weakening area, the weakening area corresponds to a preset blasting force concentration area, the weaving densities or the material strengths or the material sizes of different areas are different, the constraint force formed by the weakening area is smaller than the constraint force of other areas, an asymmetric constraint field is formed, and detonation waves are forced to diffuse in the radial direction; a plurality of crack guide grooves are formed in the positions, corresponding to the weakening area, of the pipe wall of the inner layer. Through the design of the multi-layer composite pipe body structure, a two-way constraint structure can be formed, stress is concentrated in the preset blasting direction, axial blasting dispersion is reduced, therefore, the hole plugging amount is reduced, the directional blasting energy utilization rate is increased, the structure is simple, and the installation efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of underground engineering and geotechnical engineering equipment, specifically relating to a blasting-enhanced gas fracturing tube and its operation method. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Traditional gas-fired fracturing tubes (also known as static breakers) mainly generate slow-release explosive force through chemical expansion agents or high-pressure gas, and are widely used in mining, concrete demolition and other scenarios.

[0004] Existing technologies face three main bottlenecks: First, ordinary metal pipes often fracture randomly under high pressure, resulting in uncontrollable blasting direction and energy utilization of less than 40%, and are prone to generating dangerous flyrock. Second, while homogeneous reinforcement layers can improve pipe strength, they significantly increase the detonation pressure threshold by approximately 20%-30%, leading to overall pipe rupture. Third, research published in Volume 26 of the Chinese journal *Engineering Blasting* in 2020 indicates that existing directional blasting technologies largely rely on external guiding devices, such as shaped charge shields or restraint plates, which not only increase construction costs by more than 30% but also reduce installation efficiency by 50%. In recent years, although some scholars have attempted to improve directionality by slotting the pipe, stress concentration easily occurs at the weakened areas of the slot, leading to premature detonation accidents before the working pressure is reached.

[0005] In addition, in practical applications, it has been found that the sealing length of some existing gas fracturing tubes is too long, resulting in complicated installation procedures, low construction efficiency, and inapplicability in many scenarios. Summary of the Invention

[0006] To address the aforementioned problems, this invention proposes a blast-enhanced gas fracturing tube and its operation method. Through the design of a multi-layered composite tube structure, this invention can form a bidirectional constraint structure and concentrate stress in the predetermined blasting direction, thereby improving the energy utilization rate of directional blasting. Furthermore, the simple structure enhances installation efficiency. This invention increases the blasting force inside the tunnel through constraint, reduces the sealing length, and achieves rapid sealing, rapid installation, and rapid blasting.

[0007] According to some embodiments, the present invention adopts the following technical solution: A blast-enhanced gas fracturing tube includes a gas fracturing tube body and a confinement reinforcement layer. The gas fracturing tube body is a two-layer structure with an inner and outer jacket. The inner layer has a material strength higher than a set value. The outer layer and the confinement reinforcement layer are integrally formed, and the space between the inner and outer layers is a vacuum. The constraint reinforcement layer is composed of materials with a certain strength. It is woven and has a weakened zone. The weakened zone corresponds to the predetermined explosive force concentration area. The weaving density, material strength or material size of different areas are different. The constraint force formed by the weakened zone is less than the constraint force of other areas, forming an asymmetric constraint field, which forces the detonation wave to spread radially. On the inner wall of the tube, several crack guide grooves are provided corresponding to the positions of the weakened areas.

[0008] As an alternative implementation, the inner layer is an alloy tube with a strength higher than a set value.

[0009] As an alternative implementation, the constraint reinforcement layer is made of steel wire or alloy wire.

[0010] As an alternative implementation, the weakened zone is located at the middle position of the gas fracturing tube body.

[0011] As a further embodiment, the strength of the woven material in the weakened region is lower than the strength of the woven material in other regions.

[0012] As a further embodiment, the material thickness or diameter of the weakened region is smaller than the material thickness or diameter of other regions.

[0013] As a further implementation, the weaving density of the weakened area is lower than that of other areas.

[0014] As an alternative implementation, the guide groove is a V-shaped or U-shaped structure, arranged radially along the gas fracturing tube body, with the opening of the guide groove facing the inside of the gas fracturing tube and the closed end facing the outside of the gas fracturing tube.

[0015] The operating method based on the above-mentioned explosive-enhanced gas fracturing tube includes the following steps: Insert the blast-enhanced gas fracturing tube into the pre-drilled blast hole; Liquefied gas is injected into the blast-enhanced gas fracturing tube for initiation and ignition. The constraint force formed by the constraint reinforcement layer corresponding to the predetermined explosive force concentration area is less than the constraint force in other areas, and the inner wall of the gas fracturing tube is provided with a fracturing guide groove at this location to induce the directional release of explosive force. The explosive force is concentrated and released to the predetermined explosive force concentration area to achieve directional blasting.

[0016] As an alternative implementation, when the constraint reinforcement layer is a steel wire layer, the blasting force prediction model is as follows:

[0017] in: F represents the resultant force of directional blasting, measured in N; k is the tube structure coefficient, which was determined experimentally. E is the elastic modulus of steel wire, in Pa. n represents the number of steel wires per unit length in the non-weakened zone, with units of wires / m; d is the diameter of the steel wire, in meters (m). L is the effective constraint length of the steel wire, in meters (m). P0 is the initial expansion force of the gas, with units of Pa; This is a correction factor; A represents the initial radial total cross-sectional area of ​​the steel wire, in square meters (m²).

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention sets a weakened zone in a predetermined blasting direction. By reducing the weaving density of the constraint reinforcement layer, using low-strength materials, or reducing the size parameters of the steel wire, an asymmetric weaving layer is constructed to form an asymmetric constraint field, which forces the detonation wave to diffuse radially. This makes the constraint force of the weakened zone corresponding to the predetermined blasting direction smaller and easier to blast.

[0019] This invention provides a fracturing groove on the inner wall of the tube corresponding to the weakened zone, which is radially arranged along the gas fracturing tube body. At the moment of blasting, the liquefied gas vaporizes instantly, and its volume expands hundreds of times instantly. Due to the overall constraint of the reinforcing layer, the blasting will concentrate the energy released to the weakened zone of the steel wire structure. In addition, the fracturing tube in the weakened zone is also equipped with a fracturing groove, which is most easily damaged, inducing the directional release of the blasting force and concentrating the stress in the predetermined blasting direction, reducing the axial blasting dispersion, thereby reducing the amount of hole sealing.

[0020] The fabrication process of the constraint reinforcement layer of the present invention is relatively simple, the overall structure is relatively simple, it will not increase the construction cost too much, and the integrated design with the gas fracturing tube body can ensure high installation efficiency.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is a schematic diagram of a blast-enhanced gas fracturing tube structure according to one embodiment; Figure 2 This is a schematic diagram of a crack guide groove structure according to one embodiment.

[0024] Among them, A is the non-weakened region, and B is the weakened region; 1. Inner layer, 2. Vacuum, 3. Groove, 4. Constraint reinforcement layer. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. 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 invention pertains.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0028] Where there is no conflict, the embodiments and features described in this application may be combined with each other.

[0029] Example 1 A type of explosion-enhanced gas fracturing tube, such as Figure 1 As shown, it includes a gas fracturing tube body and a constraint reinforcement layer. The gas fracturing tube body is a two-layer structure with an inner and outer jacket. The strength of the material of the inner layer 1 is higher than a set value. The outer layer and the constraint reinforcement layer 4 are integrally formed. The space between the inner layer 1 and the outer layer is a vacuum 2. The constraint reinforcement layer 4 is woven from a material with a certain strength, and the weaving density, material strength or material size are different in different areas, so that the constraint force formed by the constraint reinforcement layer 4 at the predetermined explosive force concentration area is less than the constraint force in other areas. On the inner wall of the tube, several grooves 3 are provided at positions corresponding to the predetermined explosive force concentration area.

[0030] It should be noted that the gas fracturing tube in this embodiment can be filled with liquefied liquid oxygen, liquid nitrogen, or a mixture of liquid oxygen and liquid nitrogen. When the liquid oxygen and liquid nitrogen are ignited in a confined space, they undergo an instantaneous phase change, expanding in volume by 700-800 times, resulting in a static explosion. Furthermore, this explosion is flameless, and the vibration is far lower than other blasting methods. The main function of the gas fracturing tube is to insert it into a blast hole in the absence of liquid oxygen and liquid nitrogen. After insertion, liquid is injected using specialized equipment and piping. The piping is then cut, sealed, and ignited to achieve a gas explosion.

[0031] This embodiment optimizes the structure of the gas fracturing tube, making it more adaptable to actual field engineering applications.

[0032] In this embodiment, the two walls of the gas fracturing tube are made of alloy tubes with strength higher than a set value, such as aluminum alloy, alloy steel, precision alloy, or other high-strength materials. The strength of the inner layer material can be less than that of the outer layer material.

[0033] Of course, in other embodiments, other materials can be selected, as long as they can ensure a certain level of strength.

[0034] In this embodiment, the constrained reinforcement layer 4 is made of steel wire or alloy wire.

[0035] Similarly, in other embodiments, other materials can be selected, as long as they can have a certain strength, form a binding force, and form a filamentous structure.

[0036] In this embodiment, the constraint reinforcement layer 4 corresponding to the predetermined explosive force concentration area is provided with a weakened region B; the strength of the braided material in the weakened region B is lower than the strength of the braided material in other areas (i.e., non-weakened region A), or the material thickness or diameter of the weakened region B is smaller than the material thickness or diameter of other areas; or the braiding density of the weakened region B is lower than the braiding density of other areas.

[0037] In this embodiment, taking the steel wire braided layer with the middle position as the weakened zone B as an example, the steel wire density can be reduced by a 30-50% decreasing gradient, such as... Figure 1 As shown, the weaving density is high at both ends and low in the middle.

[0038] Of course, lower-strength materials can also be used, such as replacing the 304 stainless steel wire with high-carbon steel.

[0039] This can be achieved by reducing the diameter and length of the steel wire.

[0040] Of course, in other embodiments, other methods can be used to make the weakened region B more susceptible to blasting in order to achieve directional blasting.

[0041] In this embodiment, an asymmetric constraint field is formed by the end wire bundle, which forces the detonation wave to spread radially.

[0042] Of course, in this embodiment, the rupture tube is equipped with an ignition mechanism, which can be an existing device, such as a resistance wire or an igniter. This is not an improvement of the present invention and will not be described in detail here.

[0043] In this embodiment, as Figure 2As shown, the guide groove has a V-shaped or U-shaped structure, is arranged radially along the gas fracturing tube body, and the opening of the guide groove faces the inside of the gas fracturing tube, while the closed part faces the outside of the gas fracturing tube.

[0044] Of course, in other embodiments, slots of other properties, such as straight or cross-shaped, can be used, as long as they enable the gas fracturing tube body in that part to assist in achieving directional blasting.

[0045] In this embodiment, a V-shaped fracture guide groove is provided on the inner wall of the tube corresponding to the weakened zone B. At the moment of detonation, the liquefied gas vaporizes instantly, expanding its volume several hundred times. Due to the overall constraint of the steel wire, the detonation will concentrate the energy released into the weakened zone B of the steel wire structure. The fracture tube in the weakened zone B is also equipped with a guide V-shaped groove. The V-shaped groove of the wire is most easily damaged, inducing the directional release of the explosive force.

[0046] Example 2 The operation method based on the blast-enhanced gas fracturing tube provided in Embodiment 1, for example, when applied to subway foundation pit excavation, includes the following steps: Insert the blast-enhanced gas fracturing tube into the pre-drilled blast hole; Liquefied gas is injected into the blast-enhanced gas fracturing tube for initiation and ignition. The constraint force formed by the constraint reinforcement layer 4 at the predetermined explosive force concentration area is less than the constraint force in other areas, and the inner wall of the explosive-enhanced gas fracturing tube is provided with a fracturing guide groove at this location to induce the directional release of explosive force. The explosive force is concentrated and released to the predetermined explosive force concentration area to achieve directional blasting.

[0047] When the constraint reinforcement layer 4 is a steel wire layer, the blasting force prediction model is as follows:

[0048] in: F represents the resultant force of directional blasting, measured in N; k is the tube structure coefficient, which was determined experimentally. E is the elastic modulus of steel wire, in Pa. n represents the number of steel wires per unit length in the non-weakened zone, with units of wires / m; d is the diameter of the steel wire, in meters (m). L is the effective constraint length of the steel wire, in meters (m). P0 is the initial expansion force of the gas, with units of Pa; This is a correction factor; A represents the initial radial total cross-sectional area of ​​the steel wire, in square meters (m²).

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art without creative effort within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A blast-enhanced gas fracturing tube, characterized in that, It includes a gas fracturing tube body and a confinement reinforcement layer. The gas fracturing tube body is a two-layer structure with an inner and outer jacket. The strength of the inner layer material is higher than a set value. The outer layer and the confinement reinforcement layer are integrally set, and the space between the inner and outer layers is a vacuum. The constraint reinforcement layer is woven from a material with a certain strength and has a weakening zone. The weakening zone corresponds to the predetermined explosive force concentration area. The weaving density, material strength, or material size of different areas are different. The constraint force formed by the weakening zone is less than that of other areas, forming an asymmetric constraint field that forces the detonation wave to spread radially. On the inner wall of the tube, several crack guide grooves are provided corresponding to the positions of the weakened areas.

2. The explosion-enhanced gas fracturing tube as described in claim 1, characterized in that, The inner layer is an alloy tube with a strength higher than a set value.

3. The explosion-enhanced gas fracturing tube as described in claim 1, characterized in that, The constraint reinforcement layer is made of steel wire or alloy wire.

4. The explosion-enhanced gas fracturing tube as described in claim 1, characterized in that, The weakened zone is located in the middle of the gas fracturing tube body.

5. The explosion-enhanced gas fracturing tube as described in claim 4, characterized in that, The strength of the woven material in the weakened region is lower than that in other regions.

6. The explosion-enhanced gas fracturing tube as described in claim 4, characterized in that, The material thickness or diameter of the weakened region is smaller than that of other regions.

7. The explosion-enhanced gas fracturing tube as described in claim 4, characterized in that, The weaving density of the weakened area is lower than that of other areas.

8. The explosion-enhanced gas fracturing tube as described in claim 1, characterized in that, The guide groove has a V-shaped or U-shaped structure and is arranged radially along the gas fracturing tube body. The opening of the guide groove faces the inside of the gas fracturing tube, and the closed part faces the outside of the gas fracturing tube.

9. A method for operating a blast-enhanced gas fracturing tube based on any one of claims 1-8, characterized in that, Includes the following steps: Insert the blast-enhanced gas fracturing tube into the pre-drilled blast hole; Liquefied gas is injected into the blast-enhanced gas fracturing tube for initiation and ignition. The constraint force formed by the constraint reinforcement layer corresponding to the predetermined explosive force concentration area is less than the constraint force in other areas, and the inner wall of the gas fracturing tube is provided with a fracturing guide groove at this location to induce the directional release of explosive force. The explosive force is concentrated and released to the predetermined explosive force concentration area to achieve directional blasting.

10. The operating method as described in claim 9, characterized in that, When the confinement reinforcement layer is a steel wire layer, the blasting force prediction model is as follows: in: F represents the resultant force of directional blasting, measured in N; k is the tube structure coefficient, which was determined experimentally. E is the elastic modulus of steel wire, in Pa. n represents the number of steel wires per unit length in the non-weakened zone, with units of wires / m; d is the diameter of the steel wire, in meters (m). L is the effective constraint length of the steel wire, in meters (m). P0 is the initial expansion force of the gas, with units of Pa; This is a correction factor; A represents the initial radial total cross-sectional area of ​​the steel wire, in square meters (m²).

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