Hydraulic directional fracturing device based on prism skeleton structure and construction method

Abstract

The application provides a hydraulic directional fracturing device based on a prism skeleton structure and a construction method. The device comprises a prism skeleton main body, a plurality of arc-shaped loading blocks, a plurality of radial hydraulic cavities, a plurality of radial pistons, a hydraulic main channel, a top high-pressure hydraulic connection unit, a guide limiting structure and a reset structure. The cylindrical outer contour formed by the prism skeleton main body and the plurality of arc-shaped loading blocks is suitable for various hole diameters; the arc-shaped loading blocks are driven by the radial hydraulic cavities and the radial pistons to press the hole wall along the preset radial direction, the maximum outward stroke is controlled by the guide limiting structure, accurate directional loading is realized, the loading interval between adjacent arc-shaped loading blocks forms a preferential fracturing zone, the crack is effectively induced to initiate and expand along the preset direction, and the controllability of the crack direction is improved; and the reset structure ensures that the arc-shaped loading blocks automatically retract after pressure relief, and guarantees repeated use and safety of the device.

Description

Technical Field

[0001] This invention relates to the field of geotechnical construction technology, and more specifically, to a hydraulic directional fracturing device and construction method based on a prism skeleton structure. Background Technology

[0002] With the continuous expansion of urban underground space development, the demand for rock excavation in underground engineering projects such as urban foundation pits, subway stations, underground transfer hubs, integrated utility tunnels, underground factories, and tunnels is increasing. However, the application of traditional drill-and-blast methods in some sensitive areas is limited by factors such as surrounding buildings and structures, existing underground pipelines, construction vibration, noise control, and environmental protection requirements. Compared to drill-and-blast methods, mechanized excavation has the advantages of less vibration, less disturbance, and better operational continuity, and has become one of the important excavation methods in urban underground engineering construction.

[0003] However, in actual engineering projects, we often encounter soft rock, relatively hard rock, locally hard interlayered rock masses, and weakly weathered rock masses with good integrity, low weathering degree, and high strength. These rock masses typically have poor excavability and strong resistance to breakage. When using milling machines, tunneling machines, rock breakers, or other mechanical excavation equipment, problems such as reduced cutting efficiency, abnormal wear of cutting teeth or tools, tool breakage, equipment jamming, increased energy consumption, and decreased construction efficiency are easily encountered. To improve the efficiency of subsequent mechanical excavation, it is usually necessary to pre-splitting, pre-weakening, or locally fracturing the rock mass before excavation. This involves creating artificial fissures within the rock mass within a certain range and direction to reduce the rock mass's integrity and equivalent strength.

[0004] In existing rock mass pre-splitting equipment, hydraulic splitting devices typically employ a central wedge to push splitting blocks on both sides, a hydraulic cylinder to directly push the expansion blocks, or other hydraulically driven components to apply loads to the borehole wall, causing tensile or shear failure in the rock mass. To obtain greater splitting force, existing equipment often uses large-sized hydraulic cylinders, wedges, force transmission components, and load-bearing components, resulting in a large overall outer diameter and heavy weight, and placing high demands on operating space and borehole size. In small-diameter boreholes, narrow working spaces, tunnel corners, local areas of foundation pits, and confined spaces, some existing equipment may experience problems such as difficulty in lowering into the borehole, insufficient effective deployment stroke, poor load-bearing stability, or reduced splitting efficiency.

[0005] Furthermore, existing hydraulic fracturing equipment mostly employs bidirectional symmetrical fracturing structures, fixed-azimuth fracturing structures, or circumferentially uniform loading structures. When it is necessary to form cracks with a preset direction within the rock mass, the existing devices have limited ability to adjust the loading azimuth, making it difficult to flexibly set the crack initiation direction according to engineering needs. In heterogeneous rock masses, rock masses with well-developed joints and fissures, or strata with significant in-situ stress, the crack propagation path is easily deflected by natural structural planes, rock mass heterogeneity, and the direction of in-situ stress, leading to difficulties in accurately controlling the pre-splitting range, crack connectivity, rock mass weakening degree, and subsequent excavation effects.

[0006] Therefore, it is necessary to provide a hydraulic directional cracking device and construction method that can improve the controllability of crack initiation and propagation direction. Summary of the Invention

[0007] In view of this, the present invention proposes a hydraulic directional fracturing device and construction method based on a prism skeleton structure to solve the problems existing in the prior art.

[0008] To achieve the above objectives, the present invention proposes a hydraulic directional fracturing device based on a prism skeleton structure, comprising: a prism skeleton body, multiple arc-shaped loading blocks, multiple radial hydraulic chambers, multiple radial pistons, a hydraulic main channel, a top high-pressure hydraulic connection unit, a guide and limiting structure, and a reset structure; The hydraulic main channel extends along the axial direction of the prism skeleton body and is located inside the prism skeleton body. The hydraulic main channel has an oil inlet at the top of the prism skeleton body, which is used to communicate with an external hydraulic supply device. The top high-pressure hydraulic connection unit is located at the top of the prism skeleton body and is used to fix the external hydraulic supply device. Multiple radial hydraulic chambers are arranged circumferentially inside the prism skeleton body, and one end of each radial hydraulic chamber is connected to the main hydraulic channel; Each of the radial hydraulic chambers is provided with a radial piston, and the radial piston has a piston pushing end facing the outside of the prism skeleton body; Multiple arc-shaped loading blocks are spaced apart along the outer circumference of the prism skeleton body, and each arc-shaped loading block is fixedly connected to the piston push end of the corresponding radial piston. The prism skeleton body is provided with a guide limiting structure that cooperates with each of the arc-shaped loading blocks. The guide limiting structure is used to guide each arc-shaped loading block to expand outward or retract inward along the corresponding preset radial direction, and to limit the maximum outward expansion stroke of each arc-shaped loading block. Multiple arc-shaped loading blocks are arranged around the outer periphery of the prism skeleton body in a retracted state, and together form a cylindrical outer contour that matches the borehole diameter. A loading interval zone is formed between two adjacent arc-shaped loading blocks. When each arc-shaped loading block pushes against the borehole wall outward, the borehole wall area corresponding to the loading interval zone forms a preferential fracturing zone under the loading action of the adjacent arc-shaped loading blocks, so as to induce rock mass cracks to initiate and propagate in the orientation corresponding to the preferential fracturing zone. The reset structure is used to drive the arc-shaped loading block to retract inward after the liquid supply is stopped and the pressure is released, so that the multiple arc-shaped loading blocks return to the cylindrical outer contour.

[0009] Optionally, the hydraulic directional fracturing device based on the prism skeleton structure further includes: a top-end operation positioning component; The top-end operation and positioning component is disposed at the top of the prism skeleton body and is fixedly connected, detachably connected, or integrally connected to the prism skeleton body. The top-end operation and positioning component includes at least one of an operation part, an orientation adjustment part, a fixed connection part, an anti-rotation positioning part, and an axial limiting part, and is used to lower, lift, adjust the circumferential orientation, externally fix, prevent circumferential rotation, and / or restrict axial movement of the hydraulic directional fracturing device based on the prism skeleton structure.

[0010] Optionally, the cross-section of the main body of the prism skeleton is a rhombus, an equilateral triangle, a regular quadrilateral, a regular pentagon, a regular hexagon, or other regular polygons.

[0011] Optionally, the number of the arc-shaped loading blocks is two, three, four, five, six or more, and the multiple arc-shaped loading blocks are equally spaced along the outer periphery of the prism skeleton body.

[0012] Optionally, the guide limiting structure includes at least one of the following: guide groove and slider, dovetail groove and dovetail block, guide rail and guide boss, keyway and guide key, guide pin and guide hole, limiting shoulder, limiting groove, limiting block or limiting pin.

[0013] Optionally, each of the radial hydraulic chambers is provided with at least one of the following: a throttling structure, a pressure equalization structure, a check valve, a control valve, or a pressure regulating structure, to achieve synchronous loading, staged loading, or differentiated loading of the multiple radial pistons.

[0014] Optionally, the reset structure includes a reset spring, a hydraulic return chamber, a return rod, an elastic reset element, or a combination thereof; and / or, The top high-pressure hydraulic connection unit includes at least one of a high-pressure hydraulic interface, a connecting thread, a quick connector, a transition connector, a sealing component, an anti-detachment structure, or an anti-torsion structure.

[0015] Optionally, the top operating positioning assembly includes a flange and positioning pins; the top of the prism skeleton body has multiple limiting posts, and the flange has multiple limiting holes, the limiting holes being adapted to the limiting posts; The positioning pin is located on the top of the flange and is used to drive into the rock mass structure around the borehole after the hydraulic directional fracturing device based on the prism skeleton structure is placed into the borehole.

[0016] Optionally, each of the arc-shaped loading blocks has an arc-shaped loading surface for contacting the borehole wall, and the arc-shaped loading surface is provided with anti-slip texture, friction-enhancing protrusions, serrations, rough texture, wear-resistant layer or a combination thereof.

[0017] Another aspect of the present invention proposes a hydraulic directional fracturing method based on a prism skeleton structure, which, based on the aforementioned hydraulic directional fracturing device based on a prism skeleton structure, includes the following steps: S1. Drilling and Equipment Selection: Based on the lithology, structural planes, pre-fracture range, predetermined fracturing direction and borehole diameter of the rock mass to be fractured, complete the drilling construction and select a hydraulic directional fracturing device whose outer contour is compatible with the borehole diameter. S2. Device lowering and orientation fixing: Connect the top of the device to the external hydraulic supply equipment, and lower the device to the target drilling section in the retracted state; adjust the circumferential orientation through the top operating positioning component and fix the device at the drilling opening, so that the loading interval area between adjacent arc-shaped loading blocks is aligned with the predetermined cracking direction. S3, Hydraulic drive loading: High-pressure liquid is input into the device through an external hydraulic supply device. The high-pressure liquid enters each radial hydraulic chamber through the hydraulic main channel in the center of the prism skeleton body, pushing the radial piston to move outward in the preset radial direction, thereby driving each arc-shaped loading block to move outward and tightly press against the borehole wall. S4. Directional fracturing and crack propagation: Gradually increase the hydraulic pressure to allow the hole wall area corresponding to the loading interval to form a preferential fracturing zone and initiate an initial crack; maintain or continue to increase the pressure to guide the initial crack to continue to propagate along the predetermined fracturing direction, thereby achieving directional fracturing. S5. Depressurization and Construction Completion: Stop the fluid supply and depressurize. The radial piston and arc-shaped loading block retract inward to the closed state under the action of the reset structure. Pull the entire device out of the borehole to complete the single directional fracturing operation.

[0018] Compared with the prior art, the beneficial effects of this invention are as follows: the cylindrical outer contour composed of a prism skeleton body and multiple arc-shaped loading blocks is suitable for drilling holes of various diameters; the arc-shaped loading blocks are driven by a radial hydraulic chamber and a radial piston to press against the hole wall in a preset radial direction, and the maximum outward expansion stroke is controlled by a guide and limiting structure to achieve precise directional loading; the loading interval area between adjacent arc-shaped loading blocks forms a preferential fracturing zone, effectively inducing cracks to start and expand in a preset direction, improving the controllability of crack direction; the reset structure ensures that the arc-shaped loading blocks automatically retract after pressure relief, ensuring the reusability and safe removal of the device; the top operation positioning component realizes the lowering, orientation adjustment and anti-rotation limiting, enhancing the directional fracturing effect of heterogeneous rock masses and complex strata, and improving the efficiency of subsequent mechanical excavation. Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings: Figure 1 This is a schematic diagram of the hydraulic directional fracturing device based on a prism skeleton structure in an embodiment of the present invention; Figure 2 This is a front view of the hydraulic directional fracturing device based on a prism skeleton structure in an embodiment of the present invention; Figure 3 For the present invention Figure 2 CC section view; Figure 4 for Figure 3 Enlarged view of a portion of point A in the middle; Figure 5 This is a schematic diagram of the main structure of the prism skeleton in an embodiment of the present invention; Figure 6 This is a schematic diagram of a structure with three arc-shaped loading blocks in an embodiment of the present invention; Figure 7 This is a schematic diagram of a structure with four arc-shaped loading blocks in an embodiment of the present invention; Figure 8 This is a schematic diagram of a structure with five arc-shaped loading blocks in an embodiment of the present invention; Figure 9 This is a schematic diagram of a crack-inducing device with three arc-shaped loading blocks generating cracks in an embodiment of the present invention; Figure 10 This is a schematic diagram of a crack-inducing device with four arc-shaped loading blocks generating cracks in an embodiment of the present invention; Figure 11 This is a schematic diagram of a crack-inducing device with five arc-shaped loading blocks generating cracks in an embodiment of the present invention; Figure 12This is a flowchart of a hydraulic directional cracking construction method based on a prism skeleton structure in an embodiment of the present invention.

[0020] Reference numerals: 1. Prismatic skeleton body; 2. Arc-shaped loading block; 3. Radial hydraulic chamber; 4. Radial piston; 5. Main hydraulic channel; 6. Piston pushing end; 7. First guide hole; 8. First guide post; 9. Second guide hole; 10. Second guide post; 11. Limiting slot; 12. Limiting baffle; 13. Flange; 14. Positioning pin; 15. Limiting hole; 16. Limiting post; 17. Return spring; 18. Quick connector. Detailed Implementation

[0021] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] Reference Figures 1 to 11 This embodiment proposes a hydraulic directional fracturing device based on a prism skeleton structure, including: a prism skeleton body 1, multiple arc-shaped loading blocks 2, multiple radial hydraulic chambers 3, multiple radial pistons 4, a hydraulic main channel 5, a top high-pressure hydraulic connection unit, a guide and limiting structure, and a reset structure.

[0023] The device in this embodiment uses a prism-shaped skeleton body 1 as the core load-bearing structure, and multiple radial hydraulic chambers 3, radial pistons 4, and arc-shaped loading blocks 2 are arranged circumferentially. The overall structure is compact and the outer diameter is controllable. When the arc-shaped loading blocks 2 are retracted, they together form a cylindrical outer contour that matches the borehole diameter, allowing the device to be smoothly lowered into boreholes of various diameters. It is particularly suitable for pre-splitting operations in rock masses at tunnel corners, local areas of foundation pits, and confined spaces, solving the problem that existing equipment has difficulty entering holes or has insufficient extension stroke due to the excessive size of components such as hydraulic cylinders and wedges. This device is adaptable to conventional drilling as well as small and large diameter boreholes, demonstrating strong adaptability.

[0024] The hydraulic main channel 5 extends along the axial direction of the prism skeleton body 1 and is located inside the prism skeleton body 1. The hydraulic main channel 5 has an oil inlet at the top of the prism skeleton body 1, which is used to connect with an external hydraulic supply device. A high-pressure hydraulic connection unit is located at the top of the prism skeleton body 1 to fix the external hydraulic supply device. In the above embodiment, multiple radial hydraulic chambers 3 are arranged circumferentially inside the prism skeleton body 1, and one end of the radial hydraulic chamber 3 is connected to the hydraulic main channel 5. Each radial hydraulic chamber 3 is provided with a radial piston 4, and the radial piston 4 has a piston pushing end 6 facing the outside of the prism skeleton body 1. Multiple arc-shaped loading blocks 2 are arranged circumferentially along the outer periphery of the prism skeleton body 1, and each arc-shaped loading block 2 is fixedly connected to the piston pushing end 6 of the corresponding radial piston 4.

[0025] Hydraulic fluid is synchronously supplied to each radial hydraulic chamber 3 through the main hydraulic channel 5, pushing each radial piston 4 and its connected arc-shaped loading block 2 outward along the preset radial direction defined by the guide and limiting structure, applying a controllable radial load to the borehole wall. Because a loading interval zone is formed between two adjacent arc-shaped loading blocks 2, the borehole wall area corresponding to this interval zone is not directly compressed during loading, but is loaded on both sides, thus forming a tensile stress concentration zone in this area, becoming a preferential crack initiation zone. This structural design allows the crack initiation direction to be precisely limited to the location of the loading interval zone, rather than being uniformly distributed circumferentially or occurring randomly, significantly improving the controllability of the crack initiation direction.

[0026] By adjusting the circumferential orientation of the device during its lowering, the orientation of the priority fracturing zone can be flexibly set according to engineering needs. This allows for the active guidance of cracks to extend along a preset direction in heterogeneous rock masses, rock masses with well-developed joints and fissures, or strata with significant in-situ stress. This effectively inhibits the deflection of cracks due to natural structural surfaces or in-situ stress, ensuring good consistency and predictability in the pre-fracture range, crack connectivity, and degree of rock mass weakening, thereby guaranteeing the stability of subsequent mechanical excavation results.

[0027] The prism skeleton body 1 is provided with a guide limiting structure that cooperates with each arc-shaped loading block 2. The guide limiting structure is used to guide each arc-shaped loading block 2 to expand outward or retract inward along the corresponding preset radial direction, and to limit the maximum outward expansion stroke of each arc-shaped loading block 2. Multiple arc-shaped loading blocks 2 are arranged around the outer periphery of the prism skeleton body 1 in a retracted state, and together form a cylindrical outer contour that matches the borehole diameter; a loading interval zone is formed between two adjacent arc-shaped loading blocks 2. When each arc-shaped loading block 2 pushes outward against the borehole wall, the borehole wall area corresponding to the loading interval zone forms a preferential fracturing zone under the loading action of the adjacent arc-shaped loading blocks 2, so as to induce rock mass cracks to start and propagate in the orientation corresponding to the preferential fracturing zone; the reset structure is used to drive the arc-shaped loading blocks 2 to retract inward after the fluid supply is stopped and the pressure is released, so that the multiple arc-shaped loading blocks 2 return to the cylindrical outer contour.

[0028] Multiple arc-shaped loading blocks 2 are arranged circumferentially at intervals, each independently or synchronously pressing against the borehole wall. Compared to bidirectional symmetrical or fixed-azimuth splitting structures, this device forms a multi-point non-uniform loading mode within the borehole, enabling directional tensile failure within the rock mass. This achieves efficient fracturing with lower splitting force, avoiding equipment jamming or abnormal wear due to excessive loading force. Simultaneously, the prism skeleton body 1 integrates a hydraulic main channel 5, with a top-mounted high-pressure hydraulic connection unit for quick connection to external hydraulic supply equipment, facilitating convenient operation and good work continuity. The guide and limiting structure guides the precise radial movement of the arc-shaped loading blocks 2 while limiting the maximum outward expansion stroke, preventing excessive expansion that could damage the equipment or borehole. The reset structure drives the arc-shaped loading blocks 2 to automatically retract and restore their cylindrical contour after pressure relief, facilitating smooth removal of the device from the borehole and improving construction efficiency. This embodiment of the device improves the controllability of crack initiation and propagation direction while also possessing adaptability to various borehole diameters, operational flexibility, structural reliability, and construction efficiency, providing strong technical support for pre-weakening treatment before mechanical excavation in sensitive areas of urban underground engineering.

[0029] As an optional implementation, the hydraulic directional fracturing device based on the prism skeleton structure further includes a top-end operation and positioning component. The top-end operation and positioning component is disposed at the top of the prism skeleton body 1 and is fixedly connected, detachably connected, or integrally connected to the prism skeleton body 1. The top-end operation and positioning component includes at least one of an operating part, an orientation adjustment part, a fixed connection part, an anti-rotation positioning part, and an axial limiting part, used for lowering, removing, circumferentially adjusting the orientation, externally fixing, preventing circumferential rotation, and / or limiting axial movement of the hydraulic directional fracturing device based on the prism skeleton structure.

[0030] By setting up a top-mounted operating positioning component, the overall control performance and operational accuracy of the hydraulic directional fracturing device based on the prism skeleton body 1 are significantly improved. The operating unit and fixed connection unit provide a reliable operating interface for the device to be lowered into the borehole and after construction, enabling the prism skeleton body 1 to be quickly and smoothly positioned at the preset depth in the borehole, facilitating efficient loading and unloading in narrow working spaces or inclined holes. The orientation adjustment unit can precisely rotate the prism skeleton body 1 in the circumferential direction according to engineering needs, thereby accurately adjusting the loading interval between adjacent arc-shaped loading blocks 2 to the target fracturing orientation. In conjunction with the anti-rotation positioning unit, the circumferential position is locked during high-pressure loading, which can effectively prevent the circumferential reaction force generated when the radial pistons 4 and arc-shaped loading blocks 2 press against the borehole wall from causing the prism skeleton body 1 to deflect unexpectedly, ensuring that the orientation of the priority fracturing zone remains constant in multiple pressurization cycles, significantly improving the consistency and repeatability of the crack initiation direction, especially suitable for heterogeneous rock masses or strata with significant in-situ stress that require the formation of pre-fracturing surfaces in a specific direction. The axial limiting part restricts the movement of the prism skeleton body 1 along the borehole axis, ensuring that each arc-shaped loading block 2 always acts on the preset borehole wall section, avoiding local overload, ineffective loading, or damage to the surrounding rock around the borehole opening due to axial slippage, further improving the accuracy of fracturing positioning and operational safety. At the same time, the top operating positioning component adopts a selectable structure with the prism skeleton body 1 through fixed connection, detachable connection, or integrated connection, which allows it to be flexibly configured according to different drill rod interface specifications, different working depths, and different retrieval methods. It can be rigidly connected to the drill rod to achieve precise positioning and axial advancement with the help of the drilling rig, or it can be connected to ropes or special tools to achieve rapid retrieval. This enhances the compatibility of the device with various external construction equipment such as drilling rigs, thrusters, or hoisting equipment, reduces the difficulty of on-site modification, and further expands the applicability and operational convenience of the device in complex working conditions such as boreholes of various diameters, tunnel corners, local areas of foundation pits, and inclined or inverted boreholes.

[0031] As an optional implementation, the top operating positioning assembly includes a flange 13 and a positioning pin 14. The top of the prism frame body 1 has multiple limiting posts 16, and the flange 13 has multiple limiting holes 15, which are adapted to the limiting posts 16. The positioning pin 14 is disposed on the top of the flange 13 and is used to drive into the rock mass structure surrounding the borehole after the hydraulic directional fracturing device based on the prism frame structure has been placed into the borehole. The flange 13 can serve as an operating part and an orientation adjustment part, allowing the user to hold the flange 13 for easy lowering, lowering, and circumferential orientation adjustment of the device. The positioning pin 14 can serve as a fixing connection part and an anti-rotation positioning part. After the positioning pin 14 is embedded in the rock mass structure, it can effectively fix the device and prevent circumferential rotation. The positioning pin 14 can be detachably connected to the flange 13, and the positioning pin 14 may have threads; after being screwed into the rock mass structure, it can prevent axial movement of the device.

[0032] As an optional implementation method, refer to Figures 6 to 11 The cross-section of the prism skeleton body 1 is a rhombus, equilateral triangle, regular quadrilateral, regular pentagon, regular hexagon, or other regular polygon. The number of arc-shaped loading blocks 2 is two, three, four, five, six, or more, and the multiple arc-shaped loading blocks 2 are equally spaced along the outer periphery of the prism skeleton body 1.

[0033] This optional implementation effectively improves the adaptability and loading performance of the device by flexibly setting the cross-sectional shape of the prism skeleton body 1 and the number and arrangement of the arc-shaped loading blocks 2. Compared with the circular cross-section, the polygonal cross-section of the prism skeleton body 1 makes it easier to process the radial hydraulic cavity 3 and the guide limiting structure on the side plane. Moreover, the transition between the edges and the plane can enhance the torsional stiffness and resist the deflection moment when the arc-shaped loading blocks 2 are subjected to non-uniform top pressure. In conjunction with the anti-rotation positioning part of the top operation positioning component, it further consolidates the orientation accuracy of the preferential fracture zone. The number of arc-shaped loading blocks 2 can be set to two, three, four, five, six or more as needed, and they are evenly spaced along the outer periphery of the prism skeleton body 1. When the number is small, such as two or three, the angle of the loading interval zone is large, and the tensile stress concentration is significant, which is conducive to the formation of high-strength directional cracks in intact hard rock. When the number is large, such as five or six, the evenly spaced arrangement can produce alternating and uniform loading zones and interval zones, forming multiple directional pre-cracks or regular network pre-weakening zones in heterogeneous rock masses or strata with developed joints and fractures, improving the pre-crack connectivity and uniformity. The equidistant arrangement ensures that the lateral reaction forces borne by each radial hydraulic chamber 3 and radial piston 4 are symmetrically balanced, preventing bending deformation or jamming of the prism skeleton body 1, reducing abnormal wear of the radial piston 4 and the arc-shaped loading block 2, and extending the device's reload life. Simultaneously, field engineers can quickly select configurations with different cross-sectional shapes and the number of loading blocks based on borehole diameter, rock mass strength, and target fracturing direction, achieving modular application, reducing customization costs, and expanding the device's versatility under various complex working conditions.

[0034] As an optional implementation, the guide limiting structure includes at least one of the following: a guide groove and a slider, a dovetail groove and a dovetail block, a guide rail and a guide boss, a keyway and a guide key, a guide pin and a guide hole, a limiting shoulder, a limiting groove, a limiting block, or a limiting pin. (Refer to...) Figure 3 and Figure 4 The prism skeleton body 1 has a first guide hole 7 and a second guide hole 9 on its side wall, and a first guide post 8 and a second guide post 10 on its arc-shaped loading block. The first guide hole 7 is adapted to the first guide post 8, and the second guide hole 9 is adapted to the second guide post 10. A limit groove 11 is provided at the opening of the second guide hole 9, and a limit baffle 12 is provided at the end of the second guide post 10. The limit groove 11 is used to limit the movement of the limit baffle 12, thereby limiting the maximum stroke of the arc-shaped loading block.

[0035] As an optional implementation, each radial hydraulic chamber 3 is provided with at least one of the following: a throttling structure, a pressure equalization structure, a check valve, a control valve, or a pressure regulating structure, so as to achieve synchronous loading, staged loading, or differentiated loading of multiple radial pistons 4.

[0036] As an optional implementation, the reset structure includes a reset spring 17, a hydraulic return chamber, a return rod, an elastic reset member, or a combination thereof, and the reset spring 17 may be sleeved on the second guide post 10.

[0037] The top high-pressure hydraulic connection unit includes at least one of the following: a high-pressure hydraulic interface, a connecting thread, a quick coupling 18, a transition coupling, a sealing assembly, an anti-detachment structure, or an anti-torsion structure. The quick coupling 18 is used for quick connection to an external hydraulic supply device.

[0038] As an optional implementation, each arc-shaped loading block 2 has an arc-shaped loading surface for contacting the borehole wall. The arc-shaped loading surface is provided with anti-slip textures, friction-enhancing protrusions, serrations, rough textures, a wear-resistant layer, or a combination thereof. This significantly enhances the frictional engagement and contact reliability between the arc-shaped loading block 2 and the borehole wall. The anti-slip and friction-enhancing structure effectively prevents the arc-shaped loading block 2 from sliding circumferentially or axially along the borehole wall during high-pressure loading, ensuring that the thrust transmitted by the radial piston 4 is precisely applied to the preset position, preventing the loading direction from shifting due to contact surface slippage, thereby ensuring the positioning accuracy of the preferential crack-inducing zone and the consistency of the crack initiation direction.

[0039] Compared with the prior art, the embodiments of the present invention have at least the following beneficial effects: 1. It helps improve the controllability of crack initiation location. This invention establishes a loading interval zone between adjacent arc-shaped loading blocks, causing the radial load applied by the adjacent loading blocks to the borehole wall to form a stress concentration or crack-prone area in the borehole wall region corresponding to the loading interval zone. This area constitutes a preferential crack-inducing zone. Therefore, rock mass cracks are more likely to initiate at a predetermined orientation, reducing the possibility of completely random crack propagation and improving the controllability of the pre-fracture orientation of the rock mass.

[0040] 2. Enables multi-directional directional fracturing. By adjusting the cross-sectional shape of the prism skeleton and the number of arc-shaped loading blocks, two, three, four, five or more preferential fracturing zones can be formed around the borehole, thereby achieving bidirectional, triaxial, quadriaxial, pentaxial or multiaxial directional fracturing.

[0041] This structure facilitates the construction of artificial fracture networks of different forms based on the pre-splitting profile, excavation profile, distribution of rock mass structural surfaces, mechanical excavation direction, and rock mass weakening requirements.

[0042] 3. Prismatic skeleton structures are beneficial for improving loading stability. This invention uses a prism skeleton structure as the central load-bearing body, and guides and limits the arc-shaped loading block through a guide and limiting structure, so that the arc-shaped loading block can unfold and retract in a preset radial direction.

[0043] Compared to expansion blocks or wedge blocks that lack stable guidance, this invention can reduce the risk of displacement, tilting, circumferential movement, jamming, and uneven force distribution of the loading block during high-pressure loading, which is beneficial to improving the stability and reliability of hydraulic driving force transmission to the borehole wall.

[0044] 4. The retracted state adapts to drilling and is suitable for different hole diameter conditions. Multiple arc-shaped loading blocks, when retracted, collectively form an approximately cylindrical outer contour that conforms to the borehole, facilitating the insertion of the device into a circular borehole. By adjusting the dimensions of the prism skeleton structure, the dimensions of the arc-shaped loading blocks, the curvature of the outer arc surface of the loading blocks, the radial piston stroke, and the maximum outward expansion stroke, a series of devices suitable for different borehole diameters can be formed.

[0045] Therefore, the present invention is applicable to small-diameter drilling, conventional-diameter drilling, large-diameter drilling, and rock mass pre-splitting or rock mass pre-weakening construction under different confined construction spaces.

[0046] 5. The top connection and positioning structure improves construction convenience and directional stability. This invention features a top-mounted high-pressure hydraulic connection unit that can be connected to an external hydraulic supply device. Front-end working parts with different bore diameters can use the same or compatible top-mounted hydraulic interface, thereby reducing the need for replacing hydraulic connectors and supporting equipment on site.

[0047] Meanwhile, the top-mounted operation and positioning component enables the device to be operated, its circumferential orientation adjusted, its orientation indicated, its orifice fixed, its anti-rotation positioning, and its axial limiting. Construction personnel can adjust the position of the target loading interval zone based on the orientation indicator and restrict the device's rotation and axial movement via external fixing frames, guide rods, or support structures, which helps maintain the stability of the predetermined crack-inducing direction.

[0048] 6. It helps improve loading consistency among multiple loading blocks. By setting a central hydraulic main channel, radial hydraulic chambers, and optional pressure equalization structure, throttling structure, control valve or pressure regulation structure in the hydraulic channel, multiple radial hydraulic chambers can obtain a relatively balanced hydraulic supply, which is conducive to the synchronous, phased or differentiated loading of multiple arc-shaped loading blocks.

[0049] This structure can improve the stress difference problem that may occur when multiple loading blocks work synchronously, and is conducive to implementing graded loading and directional fracturing according to actual rock mass conditions.

[0050] 7. It facilitates the pre-weakening of rock mass before mechanical excavation. This invention can create artificial cracks or crack networks with specific orientations within the rock mass before mechanical excavation, reducing the rock mass integrity and equivalent strength, and improving rock excavability. During subsequent mechanical excavation, the pre-cracked or pre-weakened rock mass can reduce cutting resistance, decrease tool wear, reduce the risk of equipment jamming, and improve mechanical excavation efficiency.

[0051] 8. It helps improve the reusability of equipment. After a single fracturing operation, this invention allows the radial piston and arc-shaped loading block to retract to a closed state under the action of a reset structure by stopping the fluid supply and depressurizing. Once the device returns to its approximately cylindrical outer contour suitable for movement within the borehole, it can be removed from the borehole and transferred to the next target section or the next borehole for continued use.

[0052] This will help improve the efficiency of equipment reuse and the continuity of construction.

[0053] Reference Figure 12 Another aspect of this invention proposes a hydraulic directional fracturing method based on a prism skeleton structure. The hydraulic directional fracturing device based on this prism skeleton structure includes the following steps: S1. Drilling and Equipment Selection: Based on the lithology, structural planes, pre-fracture range, predetermined fracturing direction and borehole diameter of the rock mass to be fractured, complete the drilling construction and select a hydraulic directional fracturing device whose outer contour is compatible with the borehole diameter. S2. Device lowering and orientation fixing: Connect the top of the device to the external hydraulic supply equipment, and lower the device to the target hole section in the retracted state; adjust the circumferential orientation through the top operating positioning component and fix the device at the hole opening, so that the loading interval area between adjacent arc-shaped loading blocks 2 is aligned with the predetermined cracking direction. S3, Hydraulic drive loading: High-pressure liquid is input to the device through an external hydraulic supply device. The high-pressure liquid enters each radial hydraulic chamber 3 through the hydraulic main channel 5 in the center of the prism skeleton body 1, pushing the radial piston 4 to move outward in the preset radial direction, thereby driving each arc-shaped loading block 2 to move outward and tightly press against the borehole wall. S4. Directional fracturing and crack propagation: Gradually increase the hydraulic pressure to allow the hole wall area corresponding to the loading interval to form a preferential fracturing zone and initiate an initial crack; maintain or continue to increase the pressure to guide the initial crack to continue to propagate along the predetermined fracturing direction, thereby achieving directional fracturing. S5. Depressurization and Construction Completion: Stop the liquid supply and depressurize. The radial piston 4 and the arc-shaped loading block 2 retract inward to the closed state under the action of the reset structure. Pull the entire device out of the borehole to complete the single directional fracturing construction.

[0054] This construction method ensures that the outer contour of the device matches the borehole diameter by matching the drilling and device selection, reducing obstruction during lowering. The top-mounted positioning component precisely adjusts the circumferential orientation, aligning the loading interval between adjacent arc-shaped loading blocks 2 with the predetermined crack initiation direction, ensuring controllable crack initiation. High-pressure liquid enters each radial hydraulic chamber 3 through the hydraulic main channel 5 at the center of the prism skeleton body 1, simultaneously pushing the radial piston 4 and the arc-shaped loading blocks 2 to press against the borehole wall. This creates tensile stress concentration in the loading interval area, inducing initial crack initiation. Gradually increasing the pressure guides the crack to expand stably along the preset direction, effectively overcoming interference from natural structural surfaces. After depressurization, the reset structure automatically drives the radial piston 4 and the arc-shaped loading blocks 2 to retract to a closed state, facilitating rapid device removal and enabling multiple loading in a single borehole or efficient continuous multi-bore operation. This method is simple to operate and, with different configurations of the prism skeleton body 1 and various numbers of arc-shaped loading blocks 2, can flexibly adapt to different lithologies and borehole diameters, significantly improving the directionality, reliability, and construction efficiency of pre-weakening in sensitive areas of urban underground engineering.

[0055] The specific steps of this method are as follows: Drilling is arranged according to the lithology of the rock mass to be fractured, the development of rock mass structural planes, the pre-fracture range, the predetermined fracture direction and the borehole diameter. Select a suitable hydraulic directional fracturing device according to the borehole diameter so that the approximately cylindrical outer contour formed when multiple arc-shaped loading blocks are in the retracted state can be lowered into the borehole. Connect the fixed-end high-pressure hydraulic connection unit of the hydraulic directional fracturing device to the external hydraulic supply equipment. The hydraulic directional fracturing device, which is in a retracted state, is lowered into the target hole section in the borehole. The circumferential orientation of the hydraulic directional fracturing device is adjusted by the top operation positioning component so that the target loading interval area between two adjacent arc-shaped loading blocks corresponds to the predetermined fracturing direction. The hydraulic directional fracturing device is connected to the orifice through the top operation positioning component, and the hydraulic directional fracturing device is circumferentially anti-rotation positioned and / or axially limited. High-pressure liquid is supplied to the hydraulic directional fracturing device through an external hydraulic supply device, and the high-pressure liquid enters each radial hydraulic chamber through the hydraulic channel in the central area of ​​the top high-pressure hydraulic connection unit and the prism skeleton structure. Under the action of high-pressure liquid, the radial pistons in each radial hydraulic chamber move outward along the corresponding preset radial direction and push the corresponding arc-shaped loading blocks outward, so that each arc-shaped loading block presses against the borehole wall. By gradually increasing the hydraulic pressure, a preferential cracking zone is formed in the hole wall area corresponding to the loading interval between adjacent arc-shaped loading blocks, and an initial crack is formed in the preferential cracking zone. Maintain or increase the hydraulic pressure to allow the initial crack to propagate along the predetermined crack-inducing direction; After the fracturing is completed, the fluid supply is stopped and the pressure is released, causing the radial piston and the arc-shaped loading block to retract inward under the action of the reset structure until the multiple arc-shaped loading blocks are restored to their cylindrical outer contours. The hydraulic directional fracturing device is pulled out of the borehole to complete a single directional fracturing operation.

[0056] The circumferential orientation of the target loading interval zone is determined by the orientation indicator located on the top operating positioning component, and the orientation indicator is aligned with the predetermined crack initiation direction. Hydraulic loading is performed using a staged loading method, which includes a wall-attached loading stage, a pre-loading stabilization stage, a crack initiation loading stage, and a pressure-holding propagation stage.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A hydraulic directional fracturing device based on a prism skeleton structure, characterized in that, include: Prismatic skeleton main body (1), multiple arc-shaped loading blocks (2), multiple radial hydraulic chambers (3), multiple radial pistons (4), hydraulic main channel (5), top high-pressure hydraulic connection unit, guide limit structure and reset structure; The hydraulic main channel (5) extends along the axial direction of the prism skeleton body (1). The hydraulic main channel (5) is located inside the prism skeleton body (1). The hydraulic main channel (5) has an oil inlet at the top of the prism skeleton body (1). The oil inlet is used to communicate with an external hydraulic supply device. The top high-pressure hydraulic connection unit is located at the top of the prism skeleton body (1) and is used to fix the external hydraulic supply device. Multiple radial hydraulic chambers (3) are arranged circumferentially inside the prism skeleton body (1), and one end of the radial hydraulic chamber (3) is connected to the hydraulic main channel (5); Each of the radial hydraulic chambers (3) is provided with a radial piston (4), and the radial piston (4) has a piston push end (6) facing the outside of the prism skeleton body (1). Multiple arc-shaped loading blocks (2) are spaced apart along the outer periphery of the prism skeleton body (1), and each arc-shaped loading block (2) is fixedly connected to the piston push end (6) of the corresponding radial piston (4); The prism skeleton body (1) is provided with a guide limiting structure that cooperates with each of the arc-shaped loading blocks (2). The guide limiting structure is used to guide each arc-shaped loading block (2) to expand outward or retract inward along the corresponding preset radial direction, and to limit the maximum outward expansion stroke of each arc-shaped loading block (2). Multiple arc-shaped loading blocks (2) are arranged around the outer periphery of the prism skeleton body (1) in a retracted state, and together form a cylindrical outer contour that is compatible with the borehole diameter; A loading interval zone is formed between two adjacent arc-shaped loading blocks (2). When each arc-shaped loading block (2) pushes against the borehole wall outward, the borehole wall area corresponding to the loading interval zone forms a preferential cracking zone under the loading action of the adjacent arc-shaped loading blocks (2), so as to induce rock mass cracks to start and expand in the orientation corresponding to the preferential cracking zone. The reset structure is used to drive the arc-shaped loading block (2) to retract inward after the liquid supply is stopped and the pressure is released, so that the multiple arc-shaped loading blocks (2) return to the cylindrical outer contour.

2. The hydraulic directional fracturing device based on a prism skeleton structure according to claim 1, characterized in that, The hydraulic directional fracturing device based on a prism skeleton structure further includes: a top-end operation positioning component; The top-end operation positioning component is disposed at the top of the prism skeleton body (1) and is fixedly connected, detachably connected or integrally connected to the prism skeleton body (1). The top-end operation positioning component includes at least one of an operation part, an orientation adjustment part, a fixed connection part, an anti-rotation positioning part and an axial limiting part, and is used to lower, lift out, adjust the circumferential orientation, externally fix, prevent circumferential rotation and / or limit axial movement of the hydraulic directional fracturing device based on the prism skeleton structure.

3. The hydraulic directional fracturing device based on a prism skeleton structure according to claim 1, characterized in that, The cross-section of the main body of the prism skeleton (1) is a rhombus, an equilateral triangle, a regular quadrilateral, a regular pentagon, a regular hexagon, or other regular polygons.

4. The hydraulic directional fracturing device based on a prism skeleton structure according to claim 1, characterized in that, The number of the arc-shaped loading blocks (2) is two, three, four, five, six or more, and the multiple arc-shaped loading blocks (2) are equally spaced along the outer periphery of the prism skeleton body (1).

5. The hydraulic directional fracturing device based on a prism skeleton structure according to claim 1, characterized in that, The guide limiting structure includes at least one of the following: guide groove and slider, dovetail groove and dovetail block, guide rail and guide boss, keyway and guide key, guide pin and guide hole, limiting shoulder, limiting groove, limiting block or limiting pin.

6. The hydraulic directional fracturing device based on a prism skeleton structure according to claim 1, characterized in that, Each of the radial hydraulic chambers (3) is provided with at least one of the following: a throttling structure, a pressure equalization structure, a check valve, a control valve, or a pressure regulating structure, so as to realize the synchronous loading, phased loading, or differentiated loading of the multiple radial pistons (4).

7. The hydraulic directional fracturing device based on a prism skeleton structure according to claim 1, characterized in that, The reset structure includes a reset spring (17), a hydraulic return chamber, a return rod, an elastic reset element, or a combination thereof; and / or, The top high-pressure hydraulic connection unit includes at least one of a high-pressure hydraulic interface, a connecting thread, a quick connector (18), a transition connector, a sealing component, an anti-detachment structure, or an anti-torsion structure.

8. The hydraulic directional fracturing device based on a prism skeleton structure according to claim 2, characterized in that, The top operating positioning assembly includes a flange (13) and a positioning pin (14); the top of the prism skeleton body (1) has multiple limiting pins (16), and the flange (13) has multiple limiting holes (15), which are adapted to the limiting pins (16). The positioning pin (14) is located on the top of the flange (13) and is used to drive into the rock mass structure around the borehole after the hydraulic directional fracturing device based on the prism skeleton structure is placed into the borehole.

9. The hydraulic directional fracturing device based on a prism skeleton structure according to claim 1, characterized in that, Each of the arc-shaped loading blocks (2) has an arc-shaped loading surface for contacting the borehole wall, and the arc-shaped loading surface is provided with anti-slip texture, friction-enhancing protrusion, tooth texture, rough texture, wear-resistant layer or a combination thereof.

10. A hydraulic directional fracturing construction method based on a prism skeleton structure, using the hydraulic directional fracturing device based on a prism skeleton structure as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Drilling and Equipment Selection: Based on the lithology, structural planes, pre-fracture range, predetermined fracturing direction and borehole diameter of the rock mass to be fractured, complete the drilling construction and select a hydraulic directional fracturing device whose outer contour is compatible with the borehole diameter. S2, Device lowering and orientation fixing: Connect the top of the device to the external hydraulic supply equipment, and lower the device to the target hole section in the retracted state; adjust the circumferential orientation through the top operation positioning component and fix the device at the hole opening, so that the loading interval area between adjacent arc-shaped loading blocks (2) is aligned with the predetermined cracking direction; S3, Hydraulic drive loading: High pressure liquid is input to the device through an external hydraulic supply device. The high pressure liquid enters each radial hydraulic chamber (3) through the hydraulic main channel (5) in the center of the prism skeleton body (1), pushing the radial piston (4) to move outward in the preset radial direction, thereby driving each arc-shaped loading block (2) to move outward and tightly press against the borehole wall; S4. Directional fracturing and crack propagation: Gradually increase the hydraulic pressure to allow the hole wall area corresponding to the loading interval to form a preferential fracturing zone and initiate an initial crack; maintain or continue to increase the pressure to guide the initial crack to continue to propagate along the predetermined fracturing direction, thereby achieving directional fracturing. S5. Depressurization and Construction End: Stop the liquid supply and depressurize. The radial piston (4) and the arc-shaped loading block (2) retract inward to the closed state under the action of the reset structure. The entire device is lifted out of the borehole to complete the single directional fracturing construction.

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