Coal mine rock stratum directional fracturing construction method adopting directional fracturing device

Abstract

The invention relates to the technical field of underground mining methods, and provides a coal mine rock stratum directional fracturing construction method adopting a directional fracturing device, which comprises the following steps: S1, prefabricating the directional fracturing device; the directional fracturing device comprises a fracturing pipe; the fracturing pipe comprises a tubular body which is formed by oppositely splicing a first semicircular pipe wall and a second semicircular pipe wall which are the same in size into a whole. The directional fracturing device further comprises a fracturing pipe connecting piece. S2, drilling operation is carried out; s3, preparing a water-soluble film medicine bag; s4, filling a water-soluble film medicine bag; s5, a directional fracturing device is installed; s6, hole sealing treatment is carried out; step S7, dissolving the water-soluble film; s8, directional fracturing is carried out; and S9, the charging hole is blocked, and the construction site is cleaned. The method is particularly suitable for a static expanding agent directional fracturing device based on the water-soluble film packaging technology, and is suitable for engineering scenes such as mining, tunneling and building demolition which need to accurately control the rock stratum fracture direction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underground mining methods, in particular to a coal mine rock stratum directional fracturing construction method using a directional fracturing device. BACKGROUND

[0002] In the fields of mine exploitation, rock engineering demolition, etc., the traditional explosive blasting technology has long dominated. However, this technology has many shortcomings that cannot be ignored. A large amount of carbon monoxide (CO) is produced during explosive blasting, which can easily lead to CO concentration exceeding the limit in the working environment, seriously threatening the life and health of construction personnel, and may also cause poisoning and suffocation accidents. At the same time, the transportation, storage and use of explosive devices are extremely difficult to manage, and there are potential safety hazards such as theft and misuse, which pose a potential threat to public safety. In addition, the vibration and flying stones produced by explosive blasting can easily cause damage to surrounding buildings and facilities, leading to civil disputes.

[0003] With the increasing requirements of the industry for safety and environmental protection, static expanding agent fracturing technology has emerged. However, the existing static expanding agent has obvious defects in actual application. Firstly, the cost is high, which limits its large-scale popularization and use; secondly, there is a lack of effective directional device and construction method, making it difficult to achieve precise directional fracturing of rock strata, often resulting in uncontrollable fracturing direction and unstable effect, leading to low construction efficiency and inability to meet the construction needs of complex projects. Therefore, it is urgent to develop a new technology that can avoid the drawbacks of traditional explosive blasting and overcome the defects of existing static expanding agents. Therefore, it is necessary to provide an improved technical solution to address the shortcomings of the existing technology. SUMMARY

[0004] The present application aims to address the above problems by providing a simple structure and convenient operation for coal mine rock stratum static directional fracturing device, and configuring the related construction method. The coal mine rock stratum directional fracturing construction method using the directional fracturing device disclosed in the present application is particularly suitable for the directional fracturing device of static expanding agent based on water-soluble film packaging technology, and is suitable for engineering scenes that require precise control of rock stratum fracture direction, such as mine exploitation, tunneling, building demolition, etc.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions: A coal mine rock stratum directional fracturing construction method using a directional fracturing device, wherein the improvement lies in that the directional fracturing construction method comprises the following steps: Step S1, prefabricating a directional fracturing device, the directional fracturing device comprising a fracturing pipe 1; the fracturing pipe 1 comprising: a tubular body formed by oppositely splicing a first semicircular pipe wall and a second semicircular pipe wall of the same size; the directional fracturing device further comprising a fracturing pipe connecting piece 5; Step S2, drilling operation; according to the design requirements, a plurality of charging holes 10 are formed in the rock stratum; the diameter of the charging hole 10 matches the outer diameter of the fracturing tube 1; a guide hole 11 is formed on both sides of each charging hole, and the parallelism error of the guide hole 11 and the charging hole 10 is ≤2°; Step S3, preparing water-soluble film explosive package; the static swelling agent is packaged in a water-soluble film explosive package with a diameter of 30 mm and a length of 30 cm according to a ratio of 3:1 with water; Step S4, filling water-soluble film explosive package; the water-soluble film explosive package 7 is sequentially loaded into the fracturing tube 1, and at the same time, a micro pressure sensor is pre-embedded around the water-soluble film explosive package 7; a plurality of fracturing tubes 1 are sequentially connected through the fracturing tube connecting piece 5; Step S5, installing directional fracturing device; the assembled fracturing tube 1 is installed into the charging hole 10, and the joint of the first semicircular tube wall and the second semicircular tube wall is consistent with the pre-fracturing direction of the rock stratum, so as to ensure the accuracy of the fracturing direction; Step S6, hole sealing treatment; the charging hole 10 is subjected to hole sealing treatment using fast-drying concrete 8, and a water injection pipe 9 with a diameter of 5 mm is pre-embedded, and the end of the water injection pipe extends to the vicinity of the water-soluble film explosive package; Step S7, dissolving water-soluble film; after water is injected into the water injection pipe 9, the water-soluble film is melted, the static swelling agent reacts with water to generate continuous swelling pressure; Step S8, directional fracturing; the swelling pressure of the static swelling agent acts on the fracturing tube 1; the fracturing tube 1 is separated along the joint of the first semicircular tube wall and the second semicircular tube wall, and the swelling pressure is concentrated on the hole wall of the charging hole 10 and the pre-fracturing direction of the rock stratum, so as to realize the directional rupture of the rock stratum; Step S9, plugging the charging hole 10 and cleaning the construction site.

[0006] Preferably, a protruding wedge 4 is arranged on the contact surface of the first semicircular tube wall and the second semicircular tube wall, and a corresponding clamping groove 3 is arranged on the contact surface of the second semicircular tube wall and the first semicircular tube wall, and the joint of the first semicircular tube wall and the second semicircular tube wall is relatively spliced into a whole through the clamping of the protruding wedge 4 and the clamping groove 3, so as to form the fracturing tube 1.

[0007] Preferably, the protruding wedge 4 is a wedge-shaped protrusion extending along the axial direction of the fracturing tube 1; the size of the clamping groove 3 matches the size of the protruding wedge 4.

[0008] Preferably, the fracturing tube connecting piece 5 comprises a disc seat 5-1, and the upper surface and the lower surface of the disc seat 5-1 are provided with the same fixing objects; the fixing objects comprise a ring matching the inner diameter of the fracturing tube 1, and two convex edges 5-2 connected to the surface of the ring as anti-skid convex edges are symmetrically arranged in the radial direction of the ring; a slot 2 matching the size of the convex edge 5-2 is further arranged on the end surface of the first semicircular tube wall and the second semicircular tube wall.

[0009] Preferably, step S3, the preparation of the water-soluble film explosive package 7 comprises: Step S3-1, a water-soluble PVA film with a thickness of 0.15-0.2 mm and an alcoholysis degree of 98%-99% is prepared by a casting method, and 0.5% TiO2 nanoparticles are added for modification, so that the water-soluble film can be dissolved in water at 20°C for 5-8 minutes, and the tensile strength of the film material is increased to 25 MPa; Step S3-2, the static expanding agent powder mainly composed of CaO is packaged as the water-soluble film explosive package 7 at a standard of 1.5 kg per package; Step S3-3, moisture-proof pretreatment; after packaging, the water-soluble film explosive package 7 is vacuum packaged, and the storage environment humidity is ≤45%.

[0010] Preferably, step S3-1 further comprises step S3-1-1, preparation of PVA solution, which comprises: first, add PVA raw material with an alcoholysis degree of 98-99% to deionized water in proportion, heat and stir to completely dissolve PVA and form a uniform high molecular solution; when the high molecular temperature drops to 60-70°C, slowly add 0.5% TiO2 nanoparticles to the PVA solution, continuously stir or use high-speed shearing dispersion equipment to treat for 20-30 minutes, to ensure that the TiO2 nanoparticles are uniformly dispersed in the solution and fully contact with the PVA molecular chain, and obtain the PVA solution.

[0011] Preferably, step S3-2 further comprises: first, add a certain amount of clean water to the stirring container, then add the corresponding mass of static expanding agent powder to the water, and finally stir into a uniform paste; the primary stirring slurry is continuously pumped within 10-15 minutes.

[0012] Preferably, step S5 comprises: setting the cracking device in the charging hole 10, adjusting the angle between the clamping groove 3 and the hole wall of the charging hole 10, so that the plane where the clamping groove 3 is located is consistent with the pre-cracking direction of the rock stratum; real-time calibration is performed using an angle ruler with an accuracy of ±1°; the gap between the protruding wedge 4 and the clamping groove 3 is 0.3-0.5 mm.

[0013] Preferably, step S8 comprises: when the expansion pressure reaches 8-10 MPa, micro-cracks first appear at the joint of the cracking tube, and as the pressure continues to increase to 15-20 MPa, the cracking tube is completely separated along the joint plane, and the expansion force is concentrated and released in the pre-cracking direction of the rock stratum.

[0014] Compared with the closest prior art, the technical scheme of the embodiment of the present application has the following beneficial effects: Directional accuracy: through the structural design of the clamping groove and the cracking tube, the directional conduction of the expansion force is realized, and the error of the cracking direction control is ≤5°, which is significantly better than the traditional technology.

[0015] Environmental safety: static expansion agent with water-soluble film packaging, no blasting dust and CO pollution, avoid the risk of management of explosive, improve the safety level of construction.

[0016] Construction efficiency: modular design of the device supports rapid installation, single-hole construction time is shortened to 1 / 3 of the traditional method, and the water-soluble film package solves the efficiency problem of powder filling.

[0017] Cost economy: compared with the static expansion agent directional device on the market, the material cost of the application is reduced by 20%, and the secondary construction cost caused by poor cracking effect is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings accompanying the specification of this application are used to provide further understanding of the application, the illustrative embodiments of the application and the description thereof are used to explain the application, and do not constitute an improper limitation on the application. Among them: Figure 1 Flow chart of the coal mine rock stratum directional fracturing construction method involved in the application; Figure 2 One of the fracturing pipe structure schematic diagrams involved in the application; Figure 3 The second fracturing pipe structure schematic diagram involved in the application; Figure 4 Fracturing pipe connecting piece structure schematic diagram involved in the application; Figure 5 Fracturing pipe water inlet structure schematic diagram involved in the application; Figure 6 Fracturing pipe installation schematic diagram involved in the application; Figure 7 One of the rock stratum directional fracturing schematic diagrams involved in the application; Figure 8 The second rock stratum directional fracturing schematic diagram involved in the application; Among them, 1, fracturing pipe; 2, slot; 3, clamping groove; 3-1, first clamping groove; 3-2, second clamping groove; 4, protruding wedge; 4-1, first protruding wedge; 4-2, second protruding wedge; 5, fracturing pipe connecting piece; 5-1, disc seat; 5-2, protruding rib; 6, water inlet; 7, water-soluble film package; 8, fast-drying concrete; 9, water injection pipe; 10, charging hole; 11, guide hole; 12, rock stratum pre-fracturing direction; 13, rock stratum. DETAILED DESCRIPTION

[0019] The application will be described in detail below with reference to the drawings and embodiments. Various examples are provided by way of explanation of the application but are not meant as limiting the application. It will be apparent to those skilled in the art that modifications and variations can be made in the present application without departing from the scope or spirit of the application. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a further embodiment. Thus, it is intended that this application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

[0020] In the following description, the terms "first / second / third" are merely to distinguish similar objects, and do not represent a specific order of the objects. Understandably, the "first / second / third" can be interchanged with a specific order or sequence as allowed, so that the embodiments of the application described herein can be implemented in an order other than that illustrated or described herein.

[0021] Unless otherwise defined, 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 belongs. The terminology used in the description herein is for describing the embodiments of the application only and is not intended to limit the application.

[0022] In the description of the application, the terms "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", etc. indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and do not require the application to be constructed and operated in a specific orientation, so it cannot be understood as a limitation of the application. The terms "connected", "connected", "provided" used in the application should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected; it can be directly connected, or it can be indirectly connected through an intermediate part; it can be wired electrical connection, wireless electrical connection, or wireless communication signal connection, and those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0023] Before further detailing the embodiments of the present disclosure, the terms and phrases involved in the embodiments of the present disclosure are explained, and the terms and phrases involved in the embodiments of the present disclosure are explained as follows.

[0024] A coal mine rock stratum directional fracturing construction method, the improvement lies in that, as shown in Figure 1 The directional fracturing construction method comprises the following steps: Step S1, prefabricate the directional fracturing device, including the fracturing pipe 1. The core of the directional fracturing device provided by the present application is the bidirectional fracturing pipe 1, the outer wall of which is arranged with the notches 2 and the clamping grooves 3 in the axial direction, the protruding structure is arranged at the position of the clamping groove, and the protruding wedge 4 can be matched to realize the rapid installation underground. The notches 2 at the two ends of the fracturing pipe are connected through the fracturing pipe connecting piece 5 to realize the series connection of multiple pipes, thereby forming a long-distance fracturing channel. The clamping groove structure of the fracturing pipe is designed as a pre-weakened ring, when the expansion force acts, the fracturing pipe can be orderly separated along the position of the clamping groove, and the expansion force is ensured to be concentrated on the pre-fracturing direction of the rock stratum.

[0025] As shown in Figure 2 and Figure 3 , the fracturing pipe 1 comprises a tubular body formed by oppositely splicing the first semicircular pipe wall and the second semicircular pipe wall with the same size. The protruding wedge 4 is arranged on the contact surface between the first semicircular pipe wall and the second semicircular pipe wall, and the corresponding clamping groove 3 is arranged on the contact surface between the second semicircular pipe wall and the first semicircular pipe wall. The first semicircular pipe wall and the second semicircular pipe wall are oppositely spliced into a whole through the clamping of the protruding wedge 4 and the clamping groove 3, thereby forming the fracturing pipe 1.

[0026] The protruding wedge 4 is a wedge-shaped protrusion extending in the axial direction of the fracturing pipe 1. The size (width, depth and length) of the clamping groove 3 is matched with the size of the protruding wedge 4.

[0027] Specifically, the fracturing pipe 1 comprises the first semicircular pipe wall and the second semicircular pipe wall with the same size. The first semicircular pipe wall and the second semicircular pipe wall are oppositely spliced to form the fracturing pipe 1.

[0028] The protruding wedge 4 can be arranged on both contact surfaces of the first semicircular pipe wall and the second semicircular pipe wall, and the corresponding clamping groove 3 can be arranged on both contact surfaces of the second semicircular pipe wall and the first semicircular pipe wall. In a preferred embodiment of the present application, the first protruding wedge 4-1 is arranged on one of the contact surfaces of the first semicircular pipe wall and the second semicircular pipe wall, and the first clamping groove 3-1 is arranged on the other contact surface. The second clamping groove 3-2 corresponding to the first protruding wedge 4-1 is arranged on one of the contact surfaces of the second semicircular pipe wall. The second protruding wedge 4-2 corresponding to the first clamping groove 3-1 is arranged on the other contact surface of the second semicircular pipe wall.

[0029] Preferably, as shown in Figure 4 , the directional fracturing device further comprises the fracturing pipe connecting piece 5 for connecting the coaxial fracturing pipes 1 in a head-to-tail manner. Specifically, the fracturing pipe connecting piece 5 comprises a disc seat 5-1, and the upper surface and the lower surface of the disc seat 5-1 are both provided with the same fixing objects. The fixing objects comprise a ring matched with the inner diameter of the fracturing pipe 1, and two convex edges 5-2 connected with the surface of the ring in the radial direction of the ring as anti-skid convex edges. The height of the convex edge 5-2 is matched with the height of the ring, and the maximum width of the convex edge 5-2 does not exceed the edge of the disc seat.

[0030] Preferably, a notch 2 matching the size of the ridge of the split tube connector 5 is also arranged on the end face of the first and second semicircular tube walls. The notch 2 is arranged at the semicircular vertex of the semicircular tube wall.

[0031] Preferably, as shown in Figure 5 In order to facilitate the water-soluble film medicine bag 7 placed in the split tube 1 to be fully contacted with water in the subsequent step, a plurality of water inlets 6 can also be uniformly arranged on the two end faces of the first and second semicircular tube walls. The water inlet 6 extends radially along the tube wall. The diameter and length of the water inlet are designed according to actual engineering needs.

[0032] The bidirectional split tube 1 is made of PVC material or Q235B steel material, has a tube diameter of 38 mm, a wall thickness of 3 mm, and a tube length of 1.5 m, and a protruding wedge 4 and a corresponding clamping groove 3 are arranged on the contact surface of the two semicircular tube walls. The protruding wedge 4 is a triangular protrusion with a height of 0.8 mm. The clamping groove 3 is symmetrically arranged on the upper part of the contact surface of the semicircular tube wall, has a depth of 1.5 mm and a width of 2 mm. The clamping groove 3 is processed by wire cutting, and has a surface roughness Ra≤1.6 μm, so as to ensure stress concentration effect and make the split tube orderly separate along the clamping groove under the expansion force of 15-20 MPa.

[0033] Multi-tube series connection: The split tubes are connected at the head and tail through the split tube connector 5. The connector is a sleeve with an inner diameter of 38 mm and a length of 8 cm. Threads (M36×2) can also be arranged on the inner walls of the two ends of the sleeve to increase threaded connection with the split tube. After connection, the overall coaxiality error is ≤0.5 mm. The outer wall of the connector is provided with anti-slip ridges. When the torque reaches 80-100 N·m, rigid connection can be formed, and the expansion force transmission efficiency is ≥90%.

[0034] Step S2, drilling operation. As shown in Figure 7 According to the design requirements, a plurality of charging holes 10 are arranged in the rock stratum 13, and the hole diameter of the charging hole 10 matches the outer diameter of the split tube 1. A guide hole 11 is arranged on both sides of each charging hole, and the parallelism error between the guide hole 11 and the charging hole 10 is ≤2°, which is used to calibrate the splitting direction.

[0035] The guide hole is an auxiliary hole, and its core function is to guide the rock stratum splitting direction and control the rock mass fracture path, so as to calibrate the splitting direction. Specifically, as shown in Figure 6The opening position of the charging hole 10 is subject to the actual engineering construction design. In an embodiment of the present application, a plurality of charging holes 10 are arranged in parallel on the designed cracking line of the rock stratum, and guide holes 11 are arranged on both sides of the charging hole. The drilling parameter design includes: according to the hardness of the rock stratum and the cracking depth requirement, a hydraulic rock drill is used to open a charging hole 10 with a diameter of 42-45 mm, and the hole depth is set according to the engineering requirement. A guide hole 11 with a diameter of 32 mm is opened at a distance of 5-8 cm from the hole wall on both sides of each charging hole, and the guide hole depth can be consistent with or slightly deeper than the charging hole. The parallelism error of the guide hole and the charging hole is ≤2°, which is used to calibrate the cracking direction.

[0036] Step S3, preparing the water-soluble film explosive package 7. The static swelling agent is packaged in a water-soluble film explosive package 7 with a diameter of 30 mm and a length of 30 cm at a ratio of 3:1 with water, ensuring the integrity of the package. The water-soluble film used in the present application is preferably made of polyvinyl alcohol (PVA) material, which has the characteristics of fast dissolution in water and no residue. The traditional powder static swelling agent is packaged into a package shape by using water-soluble film technology, and the package specification is a cylindrical body with a diameter of 30 mm and a length of 30 cm.

[0037] The preparation of the water-soluble film explosive package 7 includes: Step S3-1, a PVA water-soluble film with a thickness of 0.15-0.2 mm is prepared by using a casting method, and 0.5% TiO2 nanoparticles are added to the film material for modification, so that the water-soluble film can be dissolved in water at 20°C for 5-8 minutes, and the tensile strength of the film material is increased to 25 MPa to avoid damage during transportation.

[0038] Specifically, step S3-1-1, preparation of PVA solution. First, add PVA raw material (polyvinyl alcohol) with alcoholysis degree of 98-99% to deionized water in proportion, heat (usually 80-95°C) and stir to dissolve PVA completely, form a uniform high molecular solution (PVA solution); when the solution temperature drops to 60-70°C (to avoid high temperature affecting the dispersibility of nanoparticles), slowly add 0.5% TiO2 nanoparticles to the PVA solution, continue to stir or use high-speed shearing dispersion equipment for 20-30 minutes to ensure that the TiO2 nanoparticles are uniformly dispersed in the solution and fully contact with the PVA molecular chain. In order to ensure the dissolution rate of the PVA water-soluble film, which can dissolve quickly in water, the proportion of PVA raw material is reduced when preparing the PVA water-soluble film, and the PVA raw material is added to deionized water in proportion, including: mixing PVA raw material and deionized water in a proportion of 5-8 grams to 100 milliliters, i.e. a mass ratio of about 5%-8%.

[0039] The core reason for adding 0.5% modified TiO2 nanoparticles within the above-mentioned time is that it can ensure uniform distribution of nanoparticles in the film material, avoid local defects caused by agglomeration (affecting tensile strength), and improve the mechanical properties of the film through the interaction between nanoparticles and PVA molecules. If added before PVA dissolves, nanoparticles may be wrapped by undissolved PVA particles, leading to uneven dispersion; if added after casting into a film, it cannot enter the film material to play a modifying role, thereby affecting the regulation effect of solubility and mechanical strength.

[0040] Step S3-1-2, casting film. Pour the PVA solution at one end of the carrier, and the carrier preferably uses a polytetrafluoroethylene plate with a smooth surface for easy subsequent peeling. Uniformly spread the solution on the surface of the carrier with a scraper or a coating rod at a constant speed to form a liquid film. If a scraper is used, select the scraper gap according to the desired film thickness, and the present application uses a scraper gap of 0.15-0.2 mm. Step S3-1-3, drying and curing. Place the cast liquid film together with the carrier in a drying device and control the drying conditions: temperature and time. The drying temperature is controlled at 50-80°C. Too high a temperature can easily cause the surface to dry quickly and form a hard shell, making it difficult for internal moisture to escape, resulting in bubbles or cracking; too low a temperature will result in a long drying time. Drying time: adjust according to film thickness, generally 2-6 hours (until the film is completely dry and feels tough and not sticky).

[0041] Step S3-1-4, PVA water-soluble film peeling. After drying, the PVA film is cooled to room temperature, then gently lifted from the edge of the carrier and slowly peeled off (if peeling is difficult, a small amount of water can be added to the edge of the carrier to wet it and assist in peeling using the water-solubility of PVA). After peeling, the PVA water-soluble film can be cut to a specific size as required to form the PVA water-soluble film required by the present application.

[0042] Step S3-2, the static swelling agent powder (main component is CaO) is packaged into a water-soluble film package 7 with a diameter of 30 mm and a length of 30 cm at a standard of 1.5 kg per package. The static swelling agent ratio is: static swelling agent: water = 3:1. First, add a certain amount of clean water in the stirring container, then add the corresponding mass of static swelling agent powder to the water, and finally stir into a uniform paste. Stir quickly and ensure that the slurry is continuously pumped without interruption within 10-15 minutes after one stirring.

[0043] Step S3-3, moisture-proof pretreatment. After the water-soluble film medicine package is packaged, vacuum packaging is adopted (vacuum degree -0.08 MPa), the storage environment humidity is ≤45%, and the air pressure detection method is used to detect the sealing property of the medicine package before use. Specifically, the inside of the packaged medicine package is filled with gas through a gas source, so that the pressure reaches a preset value 0.1 MPa, and the filling is stopped. Within a preset pressure maintaining time (30 seconds), the pressure change is monitored through a pressure sensor. If the pressure drop is ≤ a standard threshold value (≤5 KPa), the sealing is qualified; if the pressure drop is > the standard threshold value (>5 KPa), there is leakage.

[0044] Step S4, as shown in Figure 6 , the water-soluble film medicine package 7 is loaded. The water-soluble film medicine packages 7 are loaded into the fracturing pipes 1 one by one, and at the same time, the micro pressure sensors are pre-embedded around the water-soluble film medicine packages, so that the swelling pressure rising rate can be monitored in real time. The plurality of fracturing pipes 1 are connected in sequence through the fracturing pipe connectors 5.

[0045] Specifically, the length of the water-soluble film medicine package is 30 cm, the length of the fracturing pipe 1 is 1.5 m, and in order to ensure that the subsequent water-soluble film medicine package can be fully contacted with water, 3-4 water-soluble film medicine packages are preferably put into the fracturing pipe 1. The 3-4 water-soluble film medicine packages are sequentially put into the first semicircular pipe wall, the second semicircular pipe wall is clamped with the first semicircular pipe wall, and the protruding wedge 4 is clamped with the clamping groove 3 to form the fracturing pipe 1. The fracturing pipe connector 5 is installed at the bottom of the fracturing pipe 1, and the anti-skid protrusions on the upper surface of the fracturing pipe connector 5 are matched and clamped with the notches 2 of the first semicircular pipe wall and the second semicircular pipe wall. The next fracturing pipe 1 is connected with the lower surface of the fracturing pipe connector 5 through the cooperation of the anti-skid protrusions and the notches 2 in the same way. In this way, the first and last ends of the plurality of fracturing pipes 1 are connected.

[0046] Step S5, as shown in Figure 7 and Figure 8 , the directional fracturing device is installed. The assembled fracturing pipe 1 is installed into the charging hole 10, and the joint of the first semicircular pipe wall and the second semicircular pipe wall is consistent with the rock pre-fracturing direction 12. Specifically, the protruding wedge 4 is fixed through the clamping groove 3 to fix the position of the device, and the orientation of the clamping groove 3 is consistent with the rock pre-fracturing direction 12, so as to ensure the accuracy of the fracturing direction.

[0047] Specifically, the directional installation of the fracturing pipe 1 includes: the assembled fracturing device is sent into the charging hole 10, the angle between the fracturing pipe clamping groove 3 and the hole wall is adjusted, the plane where the clamping groove is located is consistent with the rock pre-fracturing direction 12, an angle ruler (accuracy ±1°) is used for real-time calibration, and it is ensured that the rock can generate a crack along the fracturing direction of the fracturing pipe 1. Preferably, the gap between the protruding wedge 4 of the fracturing pipe and the clamping groove 3 is designed to be 0.3-0.5 mm, which not only ensures the convenience of installation, but also provides directional restraint force in the initial swelling stage.

[0048] Step S6, hole sealing treatment. After the installation of the fracturing tube 1 is completed, the fast-drying concrete 8 is used to seal the charging hole 10, and a water injection pipe 9 with a diameter of 5 mm is pre-embedded, with the end of the water injection pipe extending to the vicinity of the cartridge in the borehole.

[0049] Specifically, the fast-drying concrete 8, i.e. sulphoaluminate concrete, is used to seal the hole (initial setting time ≤ 15 minutes, final setting ≤ 30 minutes), and the sealing depth is 50-80 cm inward from the hole mouth. As shown in FIG. 1, a water injection hole is formed in the inner section of the charging hole 10, and a PE water injection pipe with a diameter of 5 mm is pre-embedded in the water injection hole. The end of the water injection pipe 9 is 5-10 cm away from the cartridge. 5% expanding agent (UEA-II type) is mixed into the concrete to compensate for the hardening shrinkage, to ensure that the sealing body has a tightness of ≥ 95% with the hole wall, and to prevent water injection leakage. Figure 6

[0050] Step S7, water-soluble film dissolution. After water is injected into the water injection pipe 9, the water-soluble film melts, and the static expanding agent in the water-soluble film cartridge reacts with water to generate a sustained swelling pressure.

[0051] Step S7-1, water injection parameter control: the free end of the water injection pipe 9 is connected with a quantitative water pump, a quantitative water pump is used, water is injected according to the mass ratio of the water-soluble film cartridge to water 3:1 (0.5 L of water is injected for every 1.5 kg of cartridge), the water injection pressure is controlled at 0.2-0.3 MPa, and the water injection time is ≤ 2 minutes. A one-way valve (opening pressure 0.1 MPa) is arranged at the end of the water injection pipe to prevent the backflow of slurry after the reaction of the expanding agent, and the water injection amount is monitored in real time through a flow sensor (accuracy ± 2%). The quantitative water pump is a commonly used equipment in engineering, which is a pump type equipment capable of accurately controlling the output flow or pressure. Its core feature is that under certain working conditions (such as stable rotating speed, constant system resistance, etc.), the output flow or pressure of the fluid remains constant, and it is widely used in scenes with high requirements for fluid delivery accuracy.

[0052] Step S7-2, dissolution process monitoring: after water injection, an infrared temperature detector is used to monitor the temperature in the hole (initial water temperature 20±2℃), and when the temperature rises to 40-50℃ (about 5-8 minutes), it indicates that the water-soluble film has completely dissolved, and the expanding agent begins to hydrate. A miniature pressure sensor (range 0-50 MPa, accuracy 0.1 MPa) pre-embedded near the cartridge is used to monitor the rising rate of the swelling pressure in real time, and under normal working conditions, the pressure rising rate is 1.5-2 MPa / min. It takes 5-7 days for the expanding agent to slowly swell to complete the reaction. If the swelling pressure rising rate is abnormal, the fracturing effect needs to be checked through a peeping instrument, and if the fracturing effect is not good, re-fracturing needs to be performed.

[0053] Step S8, directional fracturing. As shown in FIG. 1, the water injection pipe 9 is connected with a water injection pump, and the water injection pump is connected with a water tank. The water injection pump is controlled by a computer, and the water injection pump is connected with a water tank. Figure 8 ​As shown, the expansion pressure of the static expansion agent acts on the fracturing tube 1, the fracturing tube 1 is separated along the clamping groove 3, the expansion force is concentrated on the hole wall and the pre-fracturing direction of the rock stratum, and the directional fracture of the rock stratum is realized.

[0054] When the expansion pressure reaches 8-10MPa, the fracturing tube first produces micro-cracks at the clamping groove 3, and as the pressure continues to increase to 15-20MPa, the fracturing tube is completely separated along the clamping groove plane, and the expansion force is concentrated and released in the pre-fracturing direction of the rock stratum.

[0055] Breakage effect verification: After fracturing is completed (about 2-3 hours), the peep hole is used to detect the rock fracture surface, and the requirements are that the fracture length reaches more than 85% of the hole depth, the main fracture surface width is greater than or equal to 0.2cm, and the surrounding rock blocks have no obvious splashing. Among them, the peep hole can be arranged between the two charging holes 10; if the charging design of the interval charging is used, the middle hole is left as the peep hole.

[0056] The implementation process realizes the technical leap of the static expansion agent fracturing from "empirical construction" to "precise control" through the structure design of millimeter-level precision, the water-soluble film technology of minute-level response and the intelligent pressure regulation, and is especially suitable for the engineering scenes such as urban building demolition and subway tunnel excavation which have high requirements on environmental control.

[0057] Step S9, after fracturing is completed, the charging hole 10 is plugged, and the construction site is cleaned up.

[0058] The above is only a preferred embodiment of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for directional fracturing of coal mine rock strata using a directional fracturing device, characterized in that, The directional fracturing construction method includes the following steps: Step S1: Pre-determine a directional fracturing device, the directional fracturing device including a fracturing tube (1); the fracturing tube (1) includes: a tubular body consisting of a first semi-circular tube wall and a second semi-circular tube wall of the same size spliced ​​together to form an integral whole; the directional fracturing device also includes a fracturing tube connector (5). Step S2, drilling operation; multiple charging holes (10) are opened in the rock stratum (13) according to the design requirements; the diameter of the charging hole (10) matches the outer diameter of the fracturing tube (1); guide holes (11) are opened on both sides of each charging hole, and the parallelism error between the guide hole (11) and the charging hole (10) is ≤2°. Step S3, prepare the water-soluble film drug pack (7); mix the static swelling agent and water in a ratio of 3:1 and encapsulate them in a water-soluble film drug pack with a diameter of 30 mm and a length of 30 cm; Step S4: Fill the water-soluble film drug pack; put the water-soluble film drug pack (7) into the fracturing tube (1) one by one, and at the same time embed a miniature pressure sensor around the water-soluble film drug pack (7); the multiple fracturing tubes (1) are connected in sequence through the fracturing tube connector (5). Step S5: Install the directional fracturing device; install the assembled fracturing tube (1) into the charging hole (10), and make the junction of the first semicircular tube wall and the second semicircular tube wall consistent with the rock stratum pre-fracturing direction (12) to ensure the fracturing direction is accurate; Step S6, sealing treatment; use quick-drying concrete (8) to seal the loading hole (10), and at the same time pre-embed a water injection pipe (9) with a diameter of 5mm, the end of the water injection pipe extending to the vicinity of the water-soluble film drug pack; Step S7, the water-soluble film dissolves; after water is injected into the water injection pipe (9), the water-soluble film melts, and the static expansion agent reacts chemically with the water to generate continuous expansion pressure; Step S8, directional fracturing; the expansion pressure of the static expansion agent acts on the fracturing tube (1); the fracturing tube (1) separates along the junction of the first semicircular tube wall and the second semicircular tube wall, and the expansion pressure is concentrated on the hole wall of the charging hole (10) and the pre-fracturing direction (12) of the rock layer to achieve directional fracturing of the rock layer; Step S9: Seal the charging hole (10) and clean the construction site.

2. The method for directional fracturing of coal mine rock strata using a directional fracturing device as described in claim 1, characterized in that, A protruding wedge (4) is provided on the contact surface between the first semicircular tube wall and the second semicircular tube wall, and a corresponding slot (3) is provided on the contact surface between the second semicircular tube wall and the first semicircular tube wall. The first semicircular tube wall and the second semicircular tube wall are spliced ​​together as a whole by the protruding wedge (4) and the slot (3) to form a rupture tube (1).

3. The coal mine rock strata directional fracturing construction method using a directional fracturing device as described in claim 2, characterized in that, The protruding wedge (4) is a wedge-shaped protrusion extending axially along the rupture tube (1); the size of the slot (3) matches the size of the protruding wedge (4).

4. The method for directional fracturing of coal mine rock strata using a directional fracturing device as described in claim 1, characterized in that, The fracturing tube connector (5) includes a disc seat (5-1), and the upper and lower surfaces of the disc seat (5-1) are provided with the same fixings. The fixings include a ring that matches the inner diameter of the fracturing tube (1), and two protrusions (5-2) that are symmetrically arranged in the radial direction of the ring and connected to the surface of the ring as anti-slip protrusions. On the end faces of the first semi-circular tube wall and the second semi-circular tube wall, a groove (2) that matches the size of the protrusions (5-2) is also required.

5. The method for directional fracturing of coal mine rock strata using a directional fracturing device as described in claim 1, characterized in that, Step S3, preparing the water-soluble film drug pack (7) includes: Step S3-1: A PVA water-soluble film with a thickness of 0.15-0.2 mm and a degree of alcoholysis of 98%-99% is prepared by casting method. At the same time, 0.5% TiO2 nanoparticles are added for modification, so that the water-soluble film can be dissolved in water at 20℃ for 5-8 minutes, while improving the tensile strength of the film material to 25MPa. Step S3-2: The static expansion agent powder with CaO as the main component is packaged into the water-soluble film medicine package (7) according to the standard of 1.5kg per package. Step S3-3, moisture-proof pretreatment; the water-soluble film medicine pack (7) is vacuum packaged after sealing, and the storage environment humidity is ≤45%.

6. The method for directional fracturing of coal mine rock strata using a directional fracturing device as described in claim 5, characterized in that, Step S3-1 further includes step S3-1-1, preparation of PVA solution, including: first, adding PVA raw material with a degree of alcoholysis of 98-99% to deionized water in a certain proportion, and heating and stirring to completely dissolve PVA to form a homogeneous polymer solution; after the polymer temperature drops to 60-70℃, slowly adding 0.5% TiO2 nanoparticles to the PVA solution, and continuously stirring or using a high-speed shear dispersion device for 20-30 minutes to ensure that the TiO2 nanoparticles are uniformly dispersed in the solution and fully contacted with the PVA molecular chains to obtain the PVA solution.

7. The coal mine rock strata directional fracturing construction method using a directional fracturing device as described in claim 5, characterized in that, Step S3-2 also includes: first adding a certain amount of clean water to the mixing container, then adding the corresponding mass of static expansion agent powder to the water, and finally stirring into a uniform paste; the slurry is continuously pumped into place within 10 to 15 minutes.

8. The method for directional fracturing of coal mine rock strata using a directional fracturing device as described in claim 3, characterized in that, Step S5 includes: setting the fracturing device in the charging hole (10), adjusting the angle between the slot (3) and the wall of the charging hole (10) so that the plane of the slot (3) is consistent with the pre-fracturing direction (12) of the rock layer; using an angle ruler with an accuracy of ±1° for real-time calibration; the fitting gap between the protruding wedge (4) and the slot (3) is 0.3-0.5mm.

9. The method for directional fracturing of coal mine rock strata using a directional fracturing device as described in claim 1, characterized in that, Step S8 includes: when the expansion pressure reaches 8-10 MPa, microcracks are first generated at the junction of the fracturing tubes. As the pressure continues to increase to 15-20 MPa, the fracturing tubes completely separate along the joint plane, and the expansion force is concentrated and released in the direction of rock strata pre-fracturing (12).

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