A coal mine rock stratum directional fracturing construction method using a directional fracturing device

Abstract

The application 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: step S1, prefabricating the directional fracturing device; the directional fracturing device comprises a fracturing pipe; the fracturing pipe comprises a tubular body formed by oppositely splicing a first semicircular pipe wall and a second semicircular pipe wall which are of the same size; the directional fracturing device further comprises a fracturing pipe connecting piece; step S2, drilling operation; step S3, preparing a water-soluble film explosive package; step S4, filling the water-soluble film explosive package; step S5, installing the directional fracturing device; step S6, hole sealing treatment; step S7, water-soluble film dissolution; step S8, directional fracturing; step S9, plugging the charging hole and cleaning the construction site. The method is particularly suitable for a static expansion agent directional fracturing device based on a water-soluble film packaging technology and is suitable for engineering scenes such as mine exploitation, tunnel excavation, building demolition and the like which need to accurately control the rock stratum fracture direction.

Description

Technical Field

[0001] This application relates to the field of underground mining methods, and in particular to a method for directional fracturing of coal mine rock strata using a directional fracturing device. Background Technology

[0002] Traditional explosive blasting technology has long dominated in fields such as mining and rock demolition. However, this technology has many undeniable drawbacks. Explosive blasting generates large amounts of carbon monoxide (CO), which can easily lead to excessive CO concentrations in the work environment, seriously threatening the health and lives of construction workers and potentially causing poisoning and asphyxiation accidents. Furthermore, the transportation, storage, and use of explosives are extremely difficult to manage, posing risks of theft and misuse, and creating potential threats to public safety. In addition, the vibrations and flying debris generated by explosive blasting can easily damage surrounding buildings and facilities, leading to civil disputes.

[0003] With the increasing demands for safety and environmental protection in the industry, static expanding agent fracturing technology has emerged. However, existing static expanding agents have also revealed significant shortcomings in practical applications. Firstly, their high cost limits their large-scale promotion and use. Secondly, the lack of effective directional devices and construction methods makes it difficult to achieve precise directional fracturing of rock strata, often resulting in uncontrollable fracturing direction and unstable effects, 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. Thus, an improved technical solution addressing the aforementioned shortcomings of existing technologies is needed. Summary of the Invention

[0004] The present invention addresses the aforementioned problems by providing a simple and easy-to-operate static directional fracturing device for coal mine rock strata, along with a related construction method. This application relates to a directional fracturing construction method for coal mine rock strata using a directional fracturing device, which is particularly suitable for static expansion agent directional fracturing devices based on water-soluble film packaging technology. It is applicable to engineering scenarios requiring precise control of the rock strata fracturing direction, such as mining, tunnel excavation, and building demolition.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] An improvement of a coal mine rock strata directional fracturing construction method using a directional fracturing device is that the directional fracturing construction method includes the following steps:

[0007] Step S1: Pre-determine a directional fracturing device. The directional fracturing device includes 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 a whole. The directional fracturing device also includes a fracturing tube connector 5.

[0008] Step S2, drilling operation; multiple charging holes 10 are opened in the rock strata 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°.

[0009] Step S3: Prepare the water-soluble film drug pack; mix the static swelling agent and water in a 3:1 ratio and encapsulate them in a water-soluble film drug pack with a diameter of 30 mm and a length of 30 cm.

[0010] 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; connect multiple fracturing tubes 1 in sequence through fracturing tube connectors 5.

[0011] 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 pre-fracturing direction of the rock layer to ensure the fracturing direction is accurate.

[0012] Step S6, sealing treatment; use quick-drying concrete 8 to seal the charging 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.

[0013] 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, generating continuous expansion pressure;

[0014] 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 of the rock layer, so as to realize the directional fracturing of the rock layer.

[0015] Step S9: Seal the charging hole 10 and clean the construction site.

[0016] Preferably, 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 groove 3 is provided on the contact surface between the second semicircular tube wall and the first semicircular tube wall. By engaging the protruding wedge 4 and the groove 3, the contact points of the first semicircular tube wall and the second semicircular tube wall are spliced ​​together as a whole to form a rupture tube 1.

[0017] Preferably, the raised wedge 4 is a wedge-shaped protrusion extending along the axial direction of the rupture tube 1; the size of the slot 3 matches the size of the raised wedge 4.

[0018] Preferably, the fracturing tube connector 5 includes a disc seat 5-1, with the same fixing element provided on both the upper and lower surfaces of the disc seat 5-1; the fixing element includes a ring that matches the inner diameter of the fracturing tube 1, and two protruding ribs 5-2 that are radially symmetrically arranged on the ring and connected to the ring surface as anti-slip ribs; a groove 2 that matches the size of the protruding ribs 5-2 is also provided on the end faces of the first semi-circular tube wall and the second semi-circular tube wall.

[0019] Preferably, step S3, preparing the water-soluble film drug pack 7 includes:

[0020] 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.

[0021] Step S3-2: The static expansion agent powder, whose main component is CaO, is packaged into water-soluble film medicine packs 7 at a standard of 1.5kg per pack;

[0022] Step S3-3, moisture-proof pretreatment; after the water-soluble film medicine pack 7 is sealed, it is vacuum packaged and stored in an environment with a humidity ≤45%.

[0023] Preferably, step S3-1 further includes step S3-1-1, preparation of the 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 the 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.

[0024] Preferably, step S3-2 further 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.

[0025] Preferably, 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 of the rock stratum; using an angle ruler with an accuracy of ±1° for real-time calibration; and the fitting gap between the protruding wedge 4 and the slot 3 is 0.3-0.5mm.

[0026] Preferably, 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 pre-fracturing of the rock strata.

[0027] Compared with the closest prior art, the technical solution of this application has the following beneficial effects:

[0028] Orientational precision: Through the structural design of the slot and the fracturing tube, the expansion force is directionally transmitted, and the fracturing direction control error is ≤5°, which is significantly better than traditional technology.

[0029] Environmental safety: The static expanding agent uses water-soluble film packaging, which eliminates explosion dust and CO pollution, avoids the risks of explosives management, and improves the level of construction safety.

[0030] High construction efficiency: The modular design of the device supports rapid installation, reducing the construction time per hole to 1 / 3 of the traditional method, and the water-soluble film drug pack solves the efficiency problem of powder filling.

[0031] Cost-effectiveness: Compared with commercially available static expansion agent orientation devices, the material cost of this invention is reduced by 20%, while also reducing secondary construction costs caused by poor cracking effect. Attached Figure Description

[0032] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. Wherein:

[0033] Figure 1 This is a flowchart of the directional fracturing construction method for coal mine rock strata involved in this application;

[0034] Figure 2 This is one of the schematic diagrams of the rupture tube structure involved in this application;

[0035] Figure 3 This is the second schematic diagram of the rupture tube structure involved in this application;

[0036] Figure 4 This is a schematic diagram of the structure of the fracturing tube connector involved in this application;

[0037] Figure 5 This is a schematic diagram of the inlet structure of the fracturing pipe involved in this application;

[0038] Figure 6 This is a schematic diagram of the installation of the fracturing tube involved in this application;

[0039] Figure 7 This is one of the schematic diagrams illustrating the directional fracturing of rock strata involved in this application;

[0040] Figure 8 This is the second schematic diagram of directional fracturing of the rock strata involved in this application;

[0041] Among them, 1. fracturing tube; 2. groove; 3. slot; 3-1, first slot; 3-2, second slot; 4. protruding wedge; 4-1, first protruding wedge; 4-2, second protruding wedge; 5. fracturing tube connector; 5-1, disc seat; 5-2, protruding ridge; 6. water inlet; 7. water-soluble film chemical pack; 8. quick-drying concrete; 9. water injection pipe; 10. chemical loading hole; 11. guide hole; 12. rock stratum pre-fracturing direction; 13. rock stratum. Detailed Implementation

[0042] The present application will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will recognize that modifications and variations can be made to the present application without departing from the scope or spirit thereof. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present application encompass such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0043] In the following description, the terms "first / second / third" are used merely to distinguish similar objects and do not represent a specific order of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0044] 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 disclosure belongs. The terminology used herein is for the purpose of describing embodiments of this disclosure only and is not intended to limit this disclosure.

[0045] In the description of this application, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and do not require that this application be constructed and operated in a specific orientation, and therefore should not be construed as limiting this application. The terms "connected," "linked," and "set up" used in this application should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; direct connections or indirect connections through intermediate components; wired connections, radio connections, or wireless communication signal connections. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0046] Before providing a further detailed description of the embodiments of this disclosure, the nouns and terms involved in the embodiments of this disclosure will be explained, and the nouns and terms involved in the embodiments of this invention shall be interpreted as follows.

[0047] An improved method for directional fracturing of rock strata in coal mines, wherein the improvement lies in, for example... Figure 1 As shown, the directional cracking construction method includes the following steps:

[0048] Step S1 involves pre-designing a directional fracturing device, including a fracturing tube 1. The core of the directional fracturing device provided by this invention is a bidirectional fracturing tube 1. Its outer wall is symmetrically arranged with slots 2 and grooves 3 along the axial direction. A protruding structure is provided at the groove position, which can cooperate with a protruding wedge 4 to achieve rapid downhole installation. The slots 2 at both ends of the fracturing tube are connected in series via fracturing tube connectors 5 to form a long-distance fracturing channel. The groove structure of the fracturing tube is designed with a predetermined weak ring. When expansion force is applied, the fracturing tube can separate orderly along the groove position, ensuring that the expansion force is concentrated in the pre-fracturing direction of the rock formation.

[0049] Among them, such as Figure 2 and Figure 3 As shown, the fracturing tube 1 includes a tubular body composed of a first semicircular tube wall and a second semicircular tube wall of the same size joined together. A protruding wedge 4 is provided on the contact surface between the first and second semicircular tube walls, and a corresponding groove 3 is provided on the contact surface between the second and first semicircular tube walls. The first and second semicircular tube walls are joined together as a whole by the protruding wedge 4 and the groove 3, thus forming the fracturing tube 1.

[0050] The raised wedge 4 is a wedge-shaped protrusion extending along the axial direction of the fracture tube 1. The dimensions (width, depth, and length) of the slot 3 are matched with the dimensions of the raised wedge 4.

[0051] Specifically, the fracturing tube 1 includes a first semicircular tube wall and a second semicircular tube wall of the same size. The joint between the first semicircular tube wall and the second semicircular tube wall forms the fracturing tube 1.

[0052] A raised wedge 4 can be provided on both contact surfaces of the first and second semicircular pipe walls, and a corresponding groove 3 can be provided on both contact surfaces of the second and first semicircular pipe walls. In a preferred embodiment of this application, a first raised wedge 4-1 is provided on one contact surface of the first and second semicircular pipe walls, and a first groove 3-1 is provided on the other contact surface. A second groove 3-2 corresponding to the first raised wedge 4-1 is provided on one contact surface of the second semicircular pipe wall. A second raised wedge 4-2 corresponding to the first groove 3-1 is provided on the other contact surface of the second semicircular pipe wall.

[0053] Preferred, such as Figure 4 As shown, the directional fracturing device also includes a fracturing tube connector 5 for connecting the coaxially connected fracturing tubes 1. Specifically, the fracturing tube connector 5 includes a disc seat 5-1, with identical fixing elements on both the upper and lower surfaces of the disc seat 5-1. The fixing elements include a ring matching the inner diameter of the fracturing tube 1, and two radially symmetrically arranged protrusions 5-2 connected to the ring surface as anti-slip protrusions. The height of the protrusions 5-2 matches the height of the ring, and the maximum width of the protrusions 5-2 does not exceed the edge of the disc seat.

[0054] Preferably, a groove 2 matching the size of the protrusion of the fracture-inducing pipe connector 5 is provided on the end faces of the first and second semicircular pipe walls. The groove 2 is located at the semicircular apex of the semicircular pipe wall.

[0055] Preferred, such as Figure 5 As shown, to facilitate sufficient contact between the water-soluble film pack 7 placed inside the fracturing tube 1 and water in subsequent steps, multiple water inlets 6 can be evenly arranged on both ends of the first and second semicircular tube walls. The water inlets 6 extend radially along the tube wall. The diameter and length of the water inlets are designed according to actual engineering needs.

[0056] The bidirectional fracturing tube 1 is made of PVC or Q235B steel, with a diameter of 38mm, a wall thickness of 3mm, and a length of 1.5m. Raised wedges 4 and corresponding grooves 3 are set on the contact surfaces of the two semi-circular tube walls; the raised wedges 4 are triangular protrusions with a height of 0.8mm. Grooves 3 are symmetrically opened on the upper part of the contact surfaces of the semi-circular tube walls, with a depth of 1.5mm and a width of 2mm. The grooves 3 are machined by wire cutting, with a surface roughness Ra≤1.6μm to ensure stress concentration effect, allowing the fracturing tube to separate orderly along the grooves under an expansion force of 15-20MPa.

[0057] Multiple tubes connected in series: The fracturing tubes are connected end to end via fracturing tube connector 5. The connector is a sleeve with an inner diameter of 38mm and a length of 8cm. Threads (M36×2) can also be provided on the inner walls of both ends of the sleeve to add a threaded connection with the fracturing tube. After connection, the overall coaxiality error is ≤0.5mm. The outer wall of the connector is provided with anti-slip ridges, which can form a rigid connection when the torque reaches 80-100N·m, ensuring an expansion force transmission efficiency of ≥90%.

[0058] Step S2, drilling operation. (e.g.) Figure 7 As shown, multiple charging holes 10 are opened in the rock layer 13 according to the design requirements. The diameter of the charging holes 10 matches the outer diameter of the fracturing tube 1. Guide holes 11 are opened on both sides of each charging hole. The parallelism error between the guide holes 11 and the charging holes 10 is ≤2°, which is used to calibrate the fracturing direction.

[0059] Among them, the guide hole is an auxiliary hole, and its core function is to guide the direction of rock fracturing and control the fracture path of the rock mass, thereby calibrating the direction of fracturing. Specifically, such as... Figure 6 As shown, the location of the charging holes 10 is based on the actual engineering construction design. In one embodiment of this application, multiple charging holes 10 are arranged parallel to the designed fracturing line of the rock strata, and guide holes 11 are provided on both sides of the charging holes. The drilling parameter design includes: according to the rock hardness and fracturing depth requirements, a hydraulic rock drill is used to open charging holes 10 with a diameter of 42-45mm, and the hole depth is set according to the engineering requirements. Guide holes 11 with a diameter of 32mm are opened on both sides of each charging hole at a distance of 5-8cm from the hole wall. The depth of the guide holes can be the same as or slightly deeper than the charging holes, and the parallelism error between the guide holes and the charging holes is ≤2°, which is used to calibrate the fracturing direction.

[0060] Step S3: Prepare the water-soluble film package 7. The static expanding agent and water are mixed in a 3:1 ratio and packaged into a water-soluble film package 7 with a diameter of 30 mm and a length of 30 cm, ensuring the package remains intact. The water-soluble film involved in this application is preferably made of polyvinyl alcohol (PVA), which has the characteristics of rapid dissolution in water and no residue. The traditional powdered static expanding agent is packaged into a package using water-soluble film technology; the package is a cylindrical body with a diameter of 30 mm and a length of 30 cm.

[0061] The preparation of water-soluble film drug pack 7 includes:

[0062] Step S3-1: A PVA water-soluble film with a thickness of 0.15-0.2 mm (degree of alcoholysis 98-99%) is prepared by casting method. At the same time, 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℃ for 5-8 minutes, and the tensile strength of the film material is increased to 25 MPa to avoid damage during transportation.

[0063] Specifically, step S3-1-1 involves the preparation of the PVA solution. First, PVA raw material (polyvinyl alcohol) with a degree of hydrolysis of 98-99% is added to deionized water in a specific ratio. The PVA is then completely dissolved by heating (typically 80-95℃) and stirring to form a homogeneous polymer solution (PVA solution). Once the solution temperature drops to 60-70℃ (to avoid high temperatures affecting the dispersibility of nanoparticles), 0.5% TiO2 nanoparticles are slowly added to the PVA solution. Continuous stirring or high-speed shear dispersion is used for 20-30 minutes to ensure that the TiO2 nanoparticles are uniformly dispersed in the solution and in full contact with the PVA molecular chains. To ensure the dissolution rate of the PVA water-soluble film and allow it to dissolve quickly in water, the proportion of PVA raw material used in the preparation of the PVA water-soluble film is reduced. The proportion of PVA raw material added to deionized water includes mixing PVA raw material and deionized water at a ratio of 5-8 grams to 100 milliliters, i.e., a mass ratio of approximately 5%-8%.

[0064] The core reason for adding 0.5% modified TiO2 nanoparticles within the aforementioned timeframe is that it ensures uniform distribution of nanoparticles within the membrane material, avoiding localized defects caused by agglomeration (affecting tensile strength), and also improves the mechanical properties of the membrane through the interaction between the nanoparticles and PVA molecules. If added before PVA dissolves, the nanoparticles may be encapsulated by undissolved PVA particles, resulting in uneven dispersion; if added after casting, they cannot penetrate the membrane material to exert their modifying effect, thus affecting the control of solubility and mechanical strength.

[0065] Step S3-1-2, Casting and Film Formation. Pour the PVA solution onto one end of the carrier. Preferably, the carrier is a smooth-surfaced polytetrafluoroethylene (PTFE) plate that facilitates subsequent peeling. Use a doctor blade or coating rod to evenly spread the solution across the carrier surface, forming a liquid film. If a doctor blade is used, select the blade gap according to the required film thickness; this application uses a gap of 0.15-0.2 mm. Step S3-1-3, Drying and Curing. Place the cast liquid film along with the carrier into a drying device, controlling the drying conditions: temperature and time. The drying temperature should be controlled at 50-80℃. Excessive temperature can cause rapid surface drying, forming a hard shell that makes it difficult for internal moisture to escape, resulting in bubbles or cracking; excessively low temperature will result in excessively long drying times. Drying time: Adjusted according to film thickness, generally 2-6 hours (until the film is completely dry and feels firm and non-sticky).

[0066] Step S3-1-4: PVA water-soluble film peeling. After the dried PVA film cools to room temperature, gently lift it from the edge of the carrier and peel it off slowly (if peeling is difficult, a small amount of water can be dripped onto the edge of the carrier to moisten it, utilizing the water solubility of PVA to assist in peeling). After peeling, it can be cut to a specific size as required to finally form the PVA water-soluble film required in this application.

[0067] Step S3-2: Package the static expansion agent powder (mainly CaO) into water-soluble film packets 7, each weighing 1.5 kg and measuring 30 mm in diameter and 30 cm in length. The static expansion agent ratio is: static expansion agent: water = 3:1. First, add a measured amount of clean water to the mixing container, then add the corresponding mass of static expansion agent powder to the water, and finally stir to form a uniform paste. Stirring should be rapid, and the slurry prepared in one batch should be continuously and uninterruptedly pumped out within 10-15 minutes.

[0068] Step S3-3, Moisture-proof pretreatment. After sealing, the water-soluble film drug pack is vacuum-packed (vacuum degree -0.08MPa). The storage environment humidity is ≤45%. Before use, the drug pack's airtightness must be tested using a pressure test method. Specifically, gas is injected into the sealed drug pack through a gas source until the pressure reaches the preset value of 0.1MPa, then the inflation is stopped. Within the preset pressure holding time (30 seconds), the pressure change is monitored using a pressure sensor. If the pressure drop is ≤ the standard threshold (≤5KPa), the seal is qualified; if the pressure drop is > the standard threshold (>5KPa), there is a leak.

[0069] Step S4, as follows Figure 6 As shown, the water-soluble film-filled drug pack 7 is loaded. The water-soluble film-filled drug packs 7 are then inserted one by one into the fracturing tube 1. Simultaneously, miniature pressure sensors are pre-embedded around the water-soluble film-filled drug packs to monitor the rate of increase in expansion pressure in real time. Multiple fracturing tubes 1 are connected sequentially via fracturing tube connectors 5.

[0070] Specifically, the length of the water-soluble film pack is 30cm, and the length of the fracturing tube 1 is 1.5m. To ensure that the subsequent water-soluble film packs can fully contact the water, it is preferable to place 3-4 water-soluble film packs inside the fracturing tube 1. The 3-4 water-soluble film packs are then sequentially placed into the first semi-circular tube wall, and the second semi-circular tube wall is aligned and engaged with the first semi-circular tube wall, ensuring that the protruding wedge 4 and the groove 3 are properly engaged to form the fracturing tube 1. A fracturing tube connector 5 is installed at the bottom of the fracturing tube 1, ensuring that the anti-slip protrusions on the upper surface of the connector 5 engage with the grooves 2 of the first and second semi-circular tube walls. The next fracturing tube 1 is connected to the lower surface of the connector 5 in the same manner, using the engagement of the anti-slip protrusions and grooves 2. This process is repeated to complete the connection of multiple fracturing tubes 1.

[0071] Step S5, as follows Figure 7 and Figure 8 As shown, the directional fracturing device is installed. The assembled fracturing tube 1 is installed into the charging hole 10, ensuring that the junction of the first and second semi-circular tube walls aligns with the pre-fracturing direction 12 of the rock stratum. Specifically, the device position is fixed using a protruding wedge 4 through a slot 3, ensuring that the orientation of the slot 3 aligns with the pre-fracturing direction 12 of the rock stratum, thus ensuring accurate fracturing direction.

[0072] Specifically, the directional installation of the fracturing tube 1 includes: inserting the assembled fracturing device into the charging hole 10; adjusting the angle between the fracturing tube slot 3 and the hole wall so that the plane of the slot is aligned with the pre-fracturing direction 12 of the rock stratum; and using an angle gauge (accuracy ±1°) for real-time calibration to ensure that the rock stratum can generate cracks along the fracturing direction of the fracturing tube 1. Preferably, the fitting clearance between the fracturing tube protrusion wedge 4 and the slot 3 is designed to be 0.3-0.5mm, which ensures both ease of installation and provides directional constraint force in the early stages of expansion.

[0073] Step S6, sealing treatment. After the fracturing tube 1 is installed, quick-drying concrete 8 is used to seal the charging hole 10. At the same time, a water injection pipe 9 with a diameter of 5mm is pre-embedded, and the end of the water injection pipe extends to the vicinity of the explosive pack in the borehole.

[0074] Specifically, use quick-drying concrete 8, i.e., sulfoaluminate concrete, to seal the holes (initial setting time ≤ 15 minutes, final setting time ≤ 30 minutes), with a sealing depth of 50-80 cm from the hole opening inwards. For example... Figure 6 As shown, a water injection hole is opened inside the charging hole 10, and a PE water injection pipe with a diameter of 5mm is pre-embedded in the water injection hole. The end of the water injection pipe 9 is 5-10cm away from the charge pack. 5% expansion agent (UEA-II type) is added to the concrete to compensate for hardening shrinkage, ensure that the sealing body and the hole wall have a tightness of ≥95%, and prevent water leakage.

[0075] Step S7, water-soluble film dissolves. After water is injected into the water injection pipe 9, the water-soluble film melts, and the static expansion agent in the water-soluble film package reacts chemically with the water, generating continuous expansion pressure.

[0076] Step S7-1, Water Injection Parameter Control: The free end of the water injection pipe 9 is connected to a metering pump. Using the metering pump, water is injected at a mass ratio of 3:1 (0.5L of water per 1.5kg of drug pack). The injection pressure is controlled at 0.2-0.3MPa, and the injection time is ≤2 minutes. A one-way valve (opening pressure 0.1MPa) is installed at the end of the water injection pipe to prevent backflow of the slurry after the expansion agent reaction. Simultaneously, the injection volume is monitored in real time by a flow sensor (accuracy ±2%). The metering pump is a commonly used device in engineering, capable of precisely controlling the output flow rate or pressure. Its core characteristic is that under specific operating conditions (such as stable speed and constant system resistance), the output fluid flow rate or pressure remains constant, making it widely used in scenarios requiring high fluid delivery accuracy.

[0077] Step S7-2, Dissolution Process Monitoring: After water injection, use an infrared thermometer to monitor the temperature inside the hole (initial water temperature 20±2℃). When the temperature rises to 40-50℃ (approximately 5-8 minutes), it indicates that the water-soluble film has completely dissolved and the expanding agent has begun its hydration reaction. The rate of increase in expansion pressure is monitored in real time using a miniature pressure sensor (range 0-50MPa, accuracy 0.1MPa) pre-embedded near the chemical pack. Under normal operating conditions, the pressure increase rate is 1.5-2MPa / min. The expanding agent slowly expands until the reaction is complete, requiring 5-7 days. If the rate of increase in expansion pressure is abnormal, the expansion and cracking effect needs to be inspected using a spectral instrument. If the cracking effect is unsatisfactory, repeated cracking is required.

[0078] Step S8, directional fracturing. For example... Figure 8As shown, the expansion pressure of the static expansion agent acts on the fracturing tube 1, the fracturing tube 1 separates along the groove 3, and the expansion force is concentrated on the borehole wall and the pre-fracturing direction of the rock layer to achieve directional fracturing of the rock layer.

[0079] When the expansion pressure reaches 8-10 MPa, microcracks first appear in the fracturing tube at slot 3. As the pressure continues to increase to 15-20 MPa, the fracturing tube completely separates along the slot plane, and the expansion force is concentrated and released in the direction of rock strata pre-fracturing.

[0080] Fracturing effect verification: After fracturing is completed (approximately 2-3 hours), the fracture surface of the rock strata is inspected using a peephole. The fracture length is required to reach more than 85% of the hole depth, the width of the main fracture surface is ≥0.2cm, and there is no obvious splashing of surrounding rock fragments. The peephole can be set between two charging holes 10; if a split-hole charging design is used, the middle hole is reserved as the peephole.

[0081] This implementation process, through millimeter-level precision structural design, minute-level response water-soluble film technology, and intelligent pressure regulation, achieves a technological leap from "experience-based construction" to "precise control" of static expansion agent-induced cracking. It is particularly suitable for engineering scenarios with high environmental control requirements, such as urban building demolition and subway tunnel excavation.

[0082] Step S9: After fracturing is completed, seal the charging hole 10 and clean the construction site.

[0083] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this 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; 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). 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; a groove (2) that matches the size of the protrusions (5-2) is also provided on the end faces of the first semi-circular tube wall and the second semi-circular tube wall. 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%; 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.

2. The method for directional fracturing of coal mine rock strata using a directional fracturing device as described in claim 1, 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).

3. The method for directional fracturing of coal mine rock strata using a directional fracturing device as described in claim 1, characterized in that, Step S3-2 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.

4. The coal mine rock strata directional fracturing construction method using a directional fracturing device as described in claim 2, 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.

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 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).

Images