Self-repairing support system for altered surrounding rock of pumped storage power station

Abstract

The invention provides a self-repairing supporting system for altered surrounding rock of a pumped storage power station, and relates to the technical field of underground structure supporting, the self-repairing supporting system comprises a fractal anchoring structure, the fractal anchoring structure comprises a main anchor rod and a plurality of multi-stage bifurcated anchor rods arranged in the length extension direction of the main anchor rod, a grouting main pipe is arranged in the main anchor rod, grouting branch pipes are arranged in the multi-stage bifurcated anchor rods, and the grouting branch pipes are connected with the fractal anchoring structure; the grouting main pipe is communicated with the grouting branch pipe; the hydraulic gradient response type hierarchical repair structures are uniformly distributed on the main anchor rod and the multi-stage bifurcated anchor rod; wherein the hydraulic gradient response type hierarchical repairing structure at least comprises a first-stage repairing unit, the first-stage repairing unit comprises a first repairing agent and a first pressure triggering film wrapping the first repairing agent, and when the seepage pressure in the alteration surrounding rock reaches a first threshold value, the first pressure triggering film is broken to release the first repairing agent to fill cracks. The method has the advantages of improving the anchoring effect, automatically repairing cracks, enhancing the stability of surrounding rocks and adapting to different seepage pressures.

Description

Technical Field

[0001] The present invention relates to the technical field of underground structure support, and particularly to a self - repairing support system for altered surrounding rock of a pumped - storage power station. Background Art

[0002] Due to tectonic action or hydrothermal activity, the altered rock has significant deterioration in rock mass mineral composition and physical and mechanical properties. It has characteristics such as low strength, developed fissures, poor integrity, softening and swelling when encountering water, etc. It is extremely easy to cause safety accidents such as large deformation of the surrounding rock of the chamber, collapse, and even seepage failure, seriously threatening the safety during the construction period and operation period of the chamber. The underground powerhouse of a pumped - storage power station is usually built in rock mass. Due to the existence of natural fissures, faults or altered zones in the selected site area, groundwater will seep into the powerhouse through these weak zones. Especially under the action of high - pressure water head, the seepage phenomenon is more significant, exacerbating the danger of the altered surrounding rock. To deal with the altered surrounding rock, the commonly used measures in engineering are still ordinary bolt or cable reinforcement measures, which cannot ensure the safety of the altered surrounding rock under the long - term action of seepage water; moreover, the existing specifications for the support design of the altered surrounding rock are also blank. Summary of the Invention

[0003] An object of the present invention is to overcome at least one of the above - mentioned deficiencies of the prior art, and provide a self - repairing support system for altered surrounding rock of a pumped - storage power station, which has the advantages of improving the anchoring effect, automatically repairing cracks, enhancing the stability of the surrounding rock, and adapting to different seepage pressures.

[0004] Additional aspects and advantages of the present invention will be partly set forth in the following description, and partly will become apparent from the description, or can be learned through the practice of the present invention.

[0005] According to one aspect of the present invention, there is provided a self - repairing support system for altered surrounding rock of a pumped - storage power station, including: A fractal anchoring structure, including a main bolt and a plurality of multi - level bifurcated bolts arranged along the length extension direction of the main bolt. A grouting main pipe is arranged in the main bolt, and a grouting branch pipe is arranged in the multi - level bifurcated bolts. The grouting main pipe and the grouting branch pipe are communicated; A plurality of hydraulic - gradient - responsive hierarchical repair structures, evenly distributed on the main bolt and the multi - level bifurcated bolts; Wherein, the hydraulic - gradient - responsive hierarchical repair structure at least includes a first - level repair unit. The first - level repair unit includes a first repair agent and a first pressure - triggered membrane wrapping the first repair agent. When the seepage pressure in the altered surrounding rock reaches a first threshold value, the first pressure - triggered membrane ruptures to release the first repair agent to fill the cracks.

[0006] In some exemplary embodiments of the present invention, based on the foregoing solution, each of the multi - level bifurcated bolts includes: The first - level bifurcated rod is inclined and arranged on the main anchor rod, and has a first included angle with the main anchor rod; The second - level bifurcated rod is inclined and arranged on the first - level bifurcated rod, and has a second included angle with the first - level bifurcated rod.

[0007] In some exemplary embodiments of the present invention, based on the foregoing solution, the first - level bifurcated rods are arranged at intervals along the length extension direction of the main anchor rod, and the positions of adjacent first - level bifurcated rods are staggered at intervals of greater than or equal to 90° in the circumferential direction of the main anchor rod.

[0008] In some exemplary embodiments of the present invention, based on the foregoing solution, the main anchor rod includes a central chamber and an external chamber between the central chamber and the outer wall; The self - healing support system for the altered surrounding rock of the pumped - storage power station further includes a drain pipe; Wherein, the grouting main pipe is arranged in the central chamber, and the drain pipe is arranged in the external chamber for draining the water in the altered surrounding rock.

[0009] In some exemplary embodiments of the present invention, based on the foregoing solution, there are multiple drain pipes, and the multiple drain pipes are arranged in an array in the external chamber.

[0010] In some exemplary embodiments of the present invention, based on the foregoing solution, a number of grouting holes are also arranged on the main anchor rod, and the grouting holes communicate the grouting main pipe and the outside of the fractal anchoring structure, so that the grout can enter the anchor hole through the grouting holes.

[0011] In some exemplary embodiments of the present invention, based on the foregoing solution, the hydraulic - gradient - responsive hierarchical repair structure further includes a secondary repair unit located inside the first pressure - trigger membrane. The secondary repair unit includes a second repair agent and a second pressure - trigger membrane wrapping the second repair agent. When the seepage pressure in the altered surrounding rock reaches the second threshold, the second pressure - trigger membrane ruptures to release the second repair agent to fill the cracks.

[0012] In some exemplary embodiments of the present invention, based on the foregoing solution, the first repair agent and / or the second repair agent is a silicate - nano - bentonite composite repair agent, and after the first pressure - trigger membrane and / or the second pressure - trigger membrane rupture to release the repair agent, a nano - silica gel is formed.

[0013] In some exemplary embodiments of the present invention, based on the foregoing solution, a number of circles of hydraulic - gradient - responsive hierarchical repair structures are arranged on the main anchor rod, and each circle includes multiple hydraulic - gradient - responsive hierarchical repair structures.

[0014] In some exemplary embodiments of the present invention, based on the foregoing solution, the volume of the altered zone that the self - healing support system for the altered surrounding rock of the pumped - storage power station can repair satisfies: It is directly proportional to the volume percentage of the first repair agent and / or the second repair agent in the core of the primary repair unit and / or the secondary repair unit, the volume of the core of the primary repair unit and / or the secondary repair unit, the total length of the main anchor rod, the number of arrangements of the hydraulic gradient response type hierarchical repair structure on a single secondary bifurcated rod, and the number of arrangements of the hydraulic gradient response type hierarchical repair structure along the circumference of the main anchor rod, and inversely proportional to the arrangement spacing of the primary bifurcated rod along the main anchor rod and the arrangement spacing of the hydraulic gradient response type hierarchical repair structure along the main anchor rod.

[0015] As can be seen from the above technical solutions, the present invention has the following advantages and positive effects: The present invention enhances the anchoring effect through the fractal anchoring structure, and combines the hierarchical pressure trigger release repair agent mechanism of the hydraulic gradient response type hierarchical repair structure to realize the dynamic filling of cracks and the self-repair of surrounding rock, effectively coping with the change of seepage pressure, and having the advantages of improving the support stability, extending the service life and adapting to complex geological conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] By describing its exemplary embodiments in detail with reference to the drawings, the above and other features and advantages of the present invention will become more obvious.

[0017] Figure 1 is a schematic structural diagram in a reduced scale of an embodiment of the self-repairing support system for altered surrounding rock of a pumped storage power station of the present invention; Figure 2 is a schematic enlarged structural diagram of an embodiment of the self-repairing support system for altered surrounding rock of a pumped storage power station of the present invention; Figure 3 is a schematic cross-sectional view of an embodiment of the self-repairing support system for altered surrounding rock of a pumped storage power station of the present invention Figure 1 ; Figure 4 is a schematic cross-sectional view of an embodiment of the self-repairing support system for altered surrounding rock of a pumped storage power station of the present invention Figure 2 ; Figure 5 is a schematic cross-sectional view of an embodiment of the self-repairing support system for altered surrounding rock of a pumped storage power station of the present invention Figure 3 ; Figure 6 is a schematic cross-sectional view of an embodiment of the self-repairing support system for altered surrounding rock of a pumped storage power station of the present invention Figure 4 ; Figure 7 is a schematic cross-sectional view of an embodiment of the self-repairing support system for altered surrounding rock of a pumped storage power station of the present invention Figure 5 ; Figure 8 is a schematic cross-sectional view of an embodiment of the self-repairing support system for altered surrounding rock of a pumped storage power station of the present invention Figure 6 .

[0018] Description of Reference Numerals 1. Fractal anchoring structure; 11. Main anchor rod; 12. Multi - stage bifurcated anchor rod; 121. First - stage bifurcated rod; 122. Second - stage bifurcated rod; 123. Central chamber; 124. External chamber; 13. Grouting main pipe; 14. Grouting branch pipe; 15. Grouting hole; 2. Hydraulic - gradient - responsive hierarchical repair structure; 211. First repair agent; 212. First pressure - trigger membrane; 3. Drain pipe. Detailed Implementation Modes

[0019] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. Like reference numerals in the figures denote like or similar structures, and thus their detailed description will be omitted.

[0020] The features, structures, or characteristics described above can be combined in any suitable manner in one or more embodiments. If possible, the features discussed in each embodiment are interchangeable. In the above description, numerous specific details are provided to give a thorough understanding of the embodiments of the present invention. However, those skilled in the art will realize that the technical solutions of the present invention can be practiced without one or more of the specific details, or other methods, components, materials, etc. can be adopted. In other cases, well - known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the present invention.

[0021] Although relative terms such as "upper" and "lower" are used in the present invention to describe the relative relationship of one component of the icon to another component, these terms are used in the present invention only for convenience, for example, according to the directions of the examples described in the drawings. It can be understood that if the device of the icon is turned upside down, the component described as "upper" will become the component "lower". Other relative terms, such as "higher", "lower", "top", "bottom", "front", "rear", "left", "right", etc. also have similar meanings. When a structure is "on" another structure, it may mean that a structure is integrally formed on another structure, or that a structure is "directly" disposed on another structure, or that a structure is "indirectly" disposed on another structure through another structure.

[0022] In the present invention, the terms "a", "one", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "comprising", "including" and "having" are used to mean an open inclusion and refer to the presence of additional elements / components / etc. in addition to the listed elements / components / etc. The terms "first", "second", etc. are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0023] In the prior art, the underground powerhouse of a pumped-storage power station is often built in a rock mass containing an altered zone. Natural fissures and faults lead to intensified groundwater seepage. Under the action of high-pressure water heads, the surrounding rock is prone to softening expansion and crack propagation. Traditional bolt support only provides passive support and cannot sense changes in seepage pressure. The repair agent cannot be accurately released to the crack propagation area, and long-term water seepage is likely to cause anchoring failure. The linear structure of conventional grouting bolts is difficult to adapt to the characteristics of multi-directional fissure development, and the slurry diffusion path is single, resulting in insufficient reinforcement in local areas.

[0024] To solve the above problems, the present invention discovers the correlation between seepage pressure and surrounding rock damage and conceives to use the pressure signal as the trigger condition for the release of the repair agent. Considering that the fissures in the altered surrounding rock exhibit multi-scale fractal characteristics, the bifurcated structure of tree roots is used for reference to enhance the spatial adaptability of the anchoring system. By constructing a connected grouting network of main rods and bifurcated rods, the penetration of slurry in three-dimensional fissures is realized. Based on the law of seepage gradient distribution, a hydraulic gradient response type hierarchical repair structure 2 is set at the key nodes of the bolt to form a hierarchical repair mechanism.

[0025] Therefore, the present invention proposes a self-repairing support system for the altered surrounding rock of a pumped-storage power station. Referring to Figures 1 to 7 as shown, it includes a fractal anchoring structure 1, which includes a main bolt 11 and a number of multi-stage bifurcated bolts 12 arranged along the length extension direction of the main bolt 11. A grouting main pipe 13 is arranged inside the main bolt 11, and a grouting branch pipe 14 is arranged inside the multi-stage bifurcated bolt 12. The grouting main pipe 13 and the grouting branch pipe 14 are connected; A number of hydraulic gradient response type hierarchical repair structures 2, referring to Figure 2 as shown, are evenly distributed on the main bolt 11 and the multi-stage bifurcated bolts 12; wherein, the hydraulic gradient response type hierarchical repair structure 2 at least includes a primary repair unit. The primary repair unit includes a first repair agent 211 and a first pressure trigger film 212 wrapping the first repair agent 211. When the seepage pressure in the altered surrounding rock reaches the first threshold, the first pressure trigger film 212 ruptures to release the first repair agent 211 to fill the cracks.

[0026] The fractal anchoring structure 1 refers to a three-dimensional anchoring system with a multi-level bifurcated topology, which can be specifically realized by a tree-like branch structure. The main bolt 11 extends in a direction parallel to the axis of the bolt hole as the main trunk, and the multi-level bifurcated bolts 12 are distributed at intervals along the axial direction of the main bolt 11 to form a spatial anchoring network covering multi-directional fissures. The hydraulic gradient response type hierarchical repair structure 2 refers to a trigger-type repair unit arranged according to the distribution of seepage pressure gradient. In some embodiments, the hydraulic gradient response type hierarchical repair structure 2 can be realized by wrapping a repair agent with a pressure-sensitive polymer material, and its layout position matches the surrounding rock stress concentration area. The first pressure trigger membrane 212 refers to a sealing material layer with a predetermined rupture strength, such as a composite membrane of polyvinyl alcohol and nano-clay, and the first threshold can be set according to the permeability coefficient of the surrounding rock.

[0027] The grouting main pipe 13 and the grouting branch pipes 14 form a connected grouting channel, enabling the grout to flow along the grouting main pipe 13 into each grouting branch pipe 14, and then uniformly and efficiently filling the rock mass pores and cracks around the main bolt 11 and the multi-level bifurcated bolts 12. In this way, on the one hand, it can enhance the bonding force between the bolt and the surrounding rock, making the bolt and the surrounding rock form a tight whole, and greatly improving the reliability and stability of the anchoring. On the other hand, during the filling process of the grouting liquid, it plays a certain role in strengthening the surrounding rock, improving the mechanical properties of the surrounding rock, and reducing the risk of deformation and damage caused by the defects of the surrounding rock itself. In addition, this connected grouting structure can also flexibly adjust the grouting pressure and the grout flow rate according to the specific conditions of the surrounding rock in different areas. For areas with complex geological conditions and different degrees of rock mass fragmentation, targeted enhanced grouting can be carried out to ensure that the fractal anchoring structure 1 can exert the best anchoring efficiency under different geological conditions.

[0028] The present invention does not make specific restrictions on the material and shape of the main bolt 11. For example, in some embodiments, the main bolt 11 can also be arranged to include a central chamber 123 and an outer chamber 124 between the central chamber 123 and the outer wall; The pumped-storage power station altered surrounding rock self-repairing support system further includes a drain pipe 3; Wherein, the grouting main pipe 13 is arranged in the central chamber 123, and the drain pipe 3 is arranged in the outer chamber 124 for draining the water in the altered surrounding rock.

[0029] The central chamber 123 refers to the longitudinally penetrating channel formed inside the main bolt 11, which can be specifically realized by using seamless steel pipes or high-strength plastic pipes as the partition structure, and is used to accommodate the grouting main pipe 13 and ensure the sealing of slurry transportation. The outer chamber 124 refers to the annular space formed between the central chamber 123 and the outer wall of the main bolt 11, and is used to arrange the drain pipe 3 and form a seepage water drainage channel. In some embodiments, the main bolt 11 can be designed as a hollow cylindrical bolt formed by fiber-reinforced polymer (such as basalt fiber-reinforced polymer), and the hollow structure forms the central chamber 123 to facilitate the installation of the grouting main pipe 13. The drain pipe 3 refers to the seepage guiding device arranged in the outer chamber 124, which can be specifically realized by using seamless steel pipes, and is used to direct the seepage water in the surrounding rock fissures.

[0030] During the implementation process, the main bolt 11 is constructed as a double-chamber structure: the central chamber 123 is dedicated to the arrangement of the grouting main pipe 13, and the slurry is transported to the anchoring area through the grouting main pipe 13; the outer chamber 124 is distributed around the central chamber 123, and the built-in drain pipe 3 therein communicates with the surrounding rock fissure network. When seepage occurs in the surrounding rock, the outer chamber 124 can quickly respond to the seepage change because it is closer to the surrounding rock fissure development area. Therefore, the drain pipe 3 can preferentially capture the seepage water and discharge it to the preset drainage channel, reducing the pore water pressure inside the surrounding rock. This structural separation design enables the grouting process not to block the drainage path, and at the same time, the drainage operation does not interfere with the slurry consolidation. The two form a non-interfering collaborative working mechanism in space, effectively overcoming the technical obstacle of functional cross-interference in the traditional technology.

[0031] That is to say, the present invention can achieve the directional drainage of the seepage water in the surrounding rock, avoid the softening and swelling of the rock mass caused by the accumulation of water pressure, and at the same time maintain the structural stability of the anchoring system. By physically isolating the grouting and drainage functions, both the complete consolidation of the anchoring slurry is ensured, and a reliable seepage guidance mechanism is established, suppressing the occurrence of seepage damage from the root cause.

[0032] In some other embodiments, referring to Figure 2 As shown, the drain pipe 3 can be designed as multiple ones, and multiple drain pipes 3 are arranged in an array in the outer chamber 124. That is to say, the drain pipes 3 can be arranged in the outer chamber 124 according to regular intervals and directions, and can be specifically realized by using an orthogonal grid or a circular radial layout to ensure that the drainage channel evenly covers the area around the main bolt 11, forming a densely distributed seepage diversion path. When the seepage water pressure inside the surrounding rock increases, the seepage water is quickly diverted through the array of drain pipes 3 in the outer chamber 124 and discharged from the end of the bolt. The array arrangement enables each drain pipe 3 to undertake the seepage guidance task in a local area, avoiding the blockage or failure of a single drainage path due to overload. At the same time, the regularly arranged drain pipes 3 form a symmetric structure in space, reducing the risk of pipe body deformation caused by uneven stress and maintaining long-term drainage stability.

[0033] In addition, a number of grouting holes 15 can be designed on the main bolt 11 (refer to Figure 8 as shown), and the grouting holes 15 communicate with the main grouting pipe 13 and the outside of the fractal anchoring structure 1, so that the slurry can enter the bolt hole through the grouting holes 15.

[0034] Among them, the grouting hole 15 refers to a hole channel penetrating through the surface of the main bolt 11, which can be specifically formed by embedding a steel pipe in the external chamber 124 to process a grouting channel, and is a round hole with a diameter range of 3-8 mm, and is evenly distributed along the axial and circumferential directions of the main bolt 11. This hole channel serves as the outlet for the slurry flow, guiding the high-pressure slurry in the main grouting pipe 13 to the outer surface of the main bolt 11.

[0035] Specifically, when a cement-based or epoxy resin-based slurry is injected into the main grouting pipe 13, the slurry diffuses outward along the grouting holes 15 under the drive of pressure. After the slurry enters the annular space between the main bolt 11 and the bolt hole wall through the grouting holes 15, it penetrates into the micro-crack network of the altered rock mass under capillary action. In addition, grouting branch pipes 14 are also arranged inside the extension structure of the multi-stage bifurcated bolt 12, which promotes the slurry to flow in multiple directions along the axial and radial directions of the branch bolts, and finally forms a continuous consolidation body in three-dimensional space. This process effectively makes up for the defects of traditional bolt grouting such as slurry accumulation at the end and incomplete filling in the middle.

[0036] The present invention does not limit the specific structure of the multi-stage bifurcated bolt 12. For example, in some embodiments, the multi-stage bifurcated bolt 12 includes at least a first-stage bifurcated rod 121 and a second-stage bifurcated rod 122, refer to Figures 1 to 7 as shown, the first-stage bifurcated rod 121 is inclined on the main bolt 11 and forms a first angle with it, and the second-stage bifurcated rod 122 is inclined on the first-stage bifurcated rod 121 and forms a second angle with it.

[0037] Among them, the first-stage bifurcated rod 121 refers to a branch rod extending from the side wall of the main bolt 11, and can specifically adopt a prefabrication process to form an integral structure with the main bolt 11. This structure expands the anchoring action range through the first angle, and the range of the first angle can be controlled between 30° and 60° (such as 30°, 45°, 60°, etc.), so that the branch bolts can cover the fracture development areas in different directions around the main bolt 11. The second-stage bifurcated rod 122 refers to a secondary anchoring unit formed by bifurcating again on the first-stage bifurcated rod 121, and can specifically be made by a prefabrication and forming process. The second angle can be designed to be 45° to 90° (such as 45°, 60°, 90°, etc.) relative to the extension direction of the first-stage bifurcated rod 121, and is used to capture the secondary cracks derived from the periphery of the main crack.

[0038] In this way, after the primary bifurcated rod 121 extends from the main bolt 11 at the first included angle, the stress it bears is secondarily dispersed by the secondary bifurcated rod 122. When the main control fissure occurs in the surrounding rock, the primary bifurcated rod 121 changes its extension path through the first included angle to form an anchoring support matching the secondary fissure trend; when the secondary fissure expands around the main fissure, the secondary bifurcated rod 122 changes its extension path through the second included angle to form an anchoring support matching the secondary fissure trend. This hierarchical bifurcation structure enables the bolt system to establish a multi-level stress transfer path and form a self-similar fractal anchoring system in the fractured rock mass. It can not only increase the contact area between the bolt and the rock mass, but also dynamically adjust the anchoring direction according to the actual fissure trend, making the stress distribution more uniform. Compared with the conventional bolt that can only deal with fissures of a single scale, this structure realizes the synchronous anchoring of the main and secondary fissures through two-level bifurcation. Of course, in some embodiments, multiple secondary bifurcated rods 122 can be designed, or a tertiary bifurcated rod can be further arranged on the basis of the secondary bifurcated rod 122, and the specific setting method is determined according to the actual situation, and the present invention does not make specific limitations.

[0039] In some embodiments, referring to Figures 3 to 6 As shown, the primary bifurcated rods 121 can also be designed to be arranged at intervals in a spiral shape along the length extension direction of the main bolt 11, and the positions of adjacent primary bifurcated rods 121 are staggered at intervals of greater than or equal to 90° in the circumferential direction of the main bolt 11.

[0040] The interval setting means that the bifurcated rods are discontinuously distributed along the axis of the main bolt 11, and can be specifically realized by a fixed spacing or a variable spacing mode. By longitudinally discrete arrangement, the continuous stress transfer along the axis direction of the main bolt 11, which may cause local stress concentration, is avoided. The staggered setting means that adjacent primary bifurcated rods 121 form a spatial phase difference in the circumferential direction of the main bolt 11, and can be specifically realized by the way of being prefabricated together with the main bolt 11 in one processing. Through the circumferential dislocation distribution, a three-dimensional support network is constructed to eliminate the blind area of single-plane support.

[0041] Specifically, the axial interval arrangement makes the primary bifurcated rods 121 form discrete support nodes longitudinally, interrupts the linear propagation path of the rock mass stress along the longitudinal direction of the main bolt 11, and reduces the risk of stress superposition. The circumferential staggered arrangement makes the support directions of adjacent bifurcated rods complementary in space. For example, four primary bifurcated rods 121 are respectively located at 0°, 90°, 180°, and 270° phases in the circumferential direction to form a three-dimensional support system covering the whole circumference; or three primary bifurcated rods 121 are respectively located at 0°, 120°, and 240° phases in the circumferential direction. This spatial layout not only avoids the crushing of the rock mass caused by the multi-level bifurcated bolts 12 squeezing the rock mass at the same circumferential position, but also disperses the shear stress through multi-angle support points, and does not affect the setting of the drain pipe 3.

[0042] The hydraulic gradient responsive hierarchical repair structure 2 is arranged at the stress mutation site where the fractal anchoring structure 1 contacts the surrounding rock. When the seepage pressure exceeds the first threshold, the first pressure triggering membrane 212 is triggered to rupture, allowing the repair agent to penetrate along the crack. The hierarchical structure of the multi-stage bifurcated anchor rod 12 expands the coverage and repair volume of the repair unit, allowing the repair agent to reach the crack areas at different depths. The synergistic effect of the main anchor rod 11 and the multi-stage bifurcated anchor rod 12 can optimize the stress transfer path and disperse the shear stress generated by the deformation of the surrounding rock.

[0043] In some embodiments, the hydraulic gradient responsive hierarchical repair structure 2 can be designed to also include a secondary repair unit located inside the first pressure-triggered membrane 212, wherein the secondary repair unit includes a second repair agent and a second pressure-triggered membrane encapsulating the second repair agent. When the seepage pressure in the altered surrounding rock reaches a second threshold, the second pressure-triggered membrane ruptures to release the second repair agent to fill the cracks.

[0044] The secondary repair unit refers to an independent repair component nested inside the first pressure-triggered membrane 212, which can be implemented by a double-layer capsule structure, where the inner capsule is loaded with the second repair agent and wrapped by the second pressure-triggered membrane. This nested structure achieves staged release control of the repair agent through physical isolation.

[0045] The second pressure-triggered membrane refers to a functional material layer that responds to a specific pressure threshold, which can be implemented by using polymer films with different crosslinking densities. For example, when the second threshold pressure is higher than the first threshold, a polyvinyl alcohol film with a higher crosslinking degree is used. The rupture strength of the film is preset by the degree of molecular chain crosslinking to ensure that it ruptures at a predetermined pressure.

[0046] Specifically, when the seepage pressure of the surrounding rock reaches the first threshold, the outer first pressure trigger membrane 212 ruptures first, releasing the first repair agent 211 to fill the initial cracks. If the seepage pressure continues to increase to the second threshold, the internal second pressure trigger membrane ruptures immediately to release the second repair agent. The grading of the pressure threshold is achieved through the difference in the mechanical properties of the two trigger membranes. For example, the first threshold is set to 0.3MPa and the second threshold is set to 0.5MPa. The second repair agent continues to fill the expanded cracks under a higher pressure environment to form secondary protection. The spatial nested relationship of the two-level repair unit ensures that the repair agent is released in the order of the pressure gradient to avoid interference with the release at different thresholds.

[0047] Through the above technical solution, the present application realizes multi-stage dynamic repair of the development of cracks in the altered surrounding rock. The first repair agent 211 treats the initial cracks at a lower pressure, and the second repair agent prevents the secondary expansion of the cracks under a higher pressure environment, solving the technical defect that a single repair mechanism cannot adapt to changes in seepage pressure. The sequential release of the two-stage repair agent avoids the premature exhaustion of the repair material and ensures that it still has continuous repair capabilities when the stress state of the surrounding rock deteriorates.

[0048] Generally, the hydraulic gradient-responsive hierarchical repair structure 2 can be evenly distributed on the surfaces of the main anchor rod 11, the first-level bifurcated rod 121, and the second-level bifurcated rod 122 of the fractal anchoring structure 1. The hydraulic gradient-responsive hierarchical repair structure 2 is evenly arranged along the circumference at the non-branching part of the main anchor rod 11. Refer to Figure 7 as shown. In some embodiments, for example, in some areas with severe alteration phenomena, it can be designed that at least several circles of the hydraulic gradient-responsive hierarchical repair structure 2 are arranged on the main anchor rod 11, and each circle includes a plurality of the hydraulic gradient-responsive hierarchical repair structure 2. In addition, in some embodiments, the adjacent hydraulic gradient-responsive hierarchical repair structures 2 can be connected to form a repair agent storage cavity.

[0049] Several circles of the hydraulic gradient-responsive hierarchical repair structure 2 are distributed along the axial direction of the main anchor rod 11, and the adjacent structures form a continuous storage space through the built-in channels. When the seepage pressure at a certain place reaches the trigger threshold, the pressure trigger film of the corresponding layer ruptures to release the repair agent to fill the crack, and at the same time, the repair agent in the storage cavity is supplemented to the ruptured area through the communication channel. As the seepage pressure gradient changes, different layer structures respond in sequence to achieve the staged repair of cracks from shallow to deep. The flow path of the repair agent in the storage cavity is designed to be parallel to the axis of the main anchor rod 11 to ensure the uniformity of pressure transmission and avoid the interruption of the repair agent supply caused by local pressure exceeding the limit.

[0050] At least one of the first repair agent 211 and the second repair agent adopts a composite material of silicate and nano-bentonite, and a nano-silica gel can be generated after the corresponding pressure trigger film ruptures.

[0051] Among them, the silicate-nano-bentonite composite repair agent refers to a mixed system of a silicate substrate and nano-scale bentonite particles (expansion ratio 150%-200%). Specifically, it can be realized by mixing sodium silicate solution and modified nano-bentonite with a mass ratio of 3:1 to 5:1. The silicate (such as sodium silicate, ) undergoes a hydrolysis reaction when dissolved in water: After hydrolysis, the released forms an alkaline environment.

[0052] The main component of bentonite is montmorillonite, which has a layered structure: alternating stacking of silicon-oxygen tetrahedron layers and aluminum-oxygen octahedron layers. Interlayer cations: such as , etc., balance the negative charge of the structure and can be exchanged by other cations. Under the action of the alkaline environment, the interlayer cations are hydrated more strongly, the layer spacing expands, and at the same time, the silicate ions enhance the surface negative charge, synergistically enhancing the ion exchange ability.

[0053] Nano-silica gel refers to a three-dimensional network structure formed by the sol-gel reaction of silicate under the catalysis of bentonite. Specifically, the gel formation rate can be controlled by adjusting the silicate concentration and the particle size of bentonite, and the gel network can penetrate into the micron-scale cracks.

[0054] Specifically, when the pressure-triggered membrane ruptures due to the seepage pressure reaching the threshold, the silicate contacts the surrounding rock seepage water with nano-bentonite. The silicate dissolves into silicate ions under alkaline conditions, and the nano-bentonite releases calcium and magnesium ions through interlayer cation exchange, accelerating the polycondensation of silicate ions to form nano-silica gel. The gel fills the cracks through two mechanisms: on the one hand, the nano-bentonite swells by absorbing water to produce a physical plugging effect; on the other hand, the silicate gelation process forms a chemical bond with the surrounding rock minerals to form an anti-seepage barrier. By adjusting the ratio of silicate to bentonite, the initial setting time and final strength of the gel can be controlled to meet the crack repair requirements under different seepage pressure environments. By enhancing the dispersibility and reactivity of the silicate system with nano-bentonite, the repair agent has both ion exchange catalysis and nano-scale filling capabilities. Under the same seepage pressure, the gel can cover finer cracks than traditional materials, and the anti-seepage strength of the formed composite gel is improved.

[0055] The present application further proposes that the fractal anchoring structure 1 is a one-piece formed part.

[0056] Among them, the fractal anchoring structure 1 being a one-piece formed part means that the main anchor rod 11 and all multi-stage bifurcated anchor rods 12 form a continuous integral structure through the same manufacturing process. Specifically, it can be realized by metal casting or additive manufacturing technology. For example, it can be processed by basalt fiber reinforced polymer or directly generated by 3D printing technology to form an anchor rod assembly with fractal branches. This feature eliminates the splicing interface of traditional split anchor rods, making the fractal anchor rods have spatial continuity in mechanical properties, thus avoiding stress concentration or material property mutation caused by the connection part.

[0057] Specifically, the geometric configurations of the main anchor rod 11 and the multi-stage bifurcated anchor rods 12 form a topological continuum through integrated manufacturing, and the internal grouting main pipe 13 and the grouting branch pipes 14 of the bifurcated anchor rods form a lumen connection synchronously during the manufacturing process. When the surrounding rock deforms, the external force is evenly transmitted to each level of bifurcated anchor rods through the continuous material structure of the fractal anchor rods, avoiding local stress peaks caused by material discontinuity at the traditional welding or threaded connection parts. When the anchoring system bears seepage pressure, the one-piece formed structure eliminates the corrosion penetration path at the split connection interface, preventing groundwater from invading along the connection gap and causing corrosion of the anchor rods.

[0058] In some specific embodiments, the main anchor rod 11 and the bifurcated anchor rods can be integrally processed from corrosion-resistant alloy materials, and the processing die is designed according to the fractal geometry parameters for the bifurcation angle and the number of levels. In another embodiment, the laser melting deposition technology can be used to stack layer by layer to form an anchor rod with a complex fractal structure, ensuring the continuity of the microcrystalline phase structure of each multi-level bifurcated anchor rod 12 and the main anchor rod 11.

[0059] In addition, the volume of the altered surrounding rock self-repairing support system of the present invention that can be repaired satisfies: Among them, is the volume percentage of the first repair agent 211 and the second repair agent in the primary repair unit and the secondary repair unit, is the volume of the primary repair unit and the secondary repair unit; is the total length of the main anchor rod 11; is the number of arrangements of the hydraulic gradient-responsive hierarchical repair structure 2 on a single secondary bifurcated rod 122; is the arrangement spacing of the primary bifurcated rod 121 along the main anchor rod 11; is the number of arrangements of the hydraulic gradient-responsive hierarchical repair structure 2 in one circumference along the main anchor rod 11; is the arrangement spacing of the hydraulic gradient-responsive hierarchical repair structure 2 along the main anchor rod 11; m is the number of secondary bifurcated rods 122 on a single primary bifurcated rod 121.

[0060] That is to say, assuming that the altered zone forms a crack with an equivalent height of 10 cm, a length of 20 cm, and a width of 1 cm, with a cavity of about 200 cm³; assuming that the outermost layer of the hierarchical repair unit is a sphere with a diameter of 1 cm, the volume is 4 / 3πr³ = 0.52 cm³, and the repair agents in the inner and outer layers account for 90% of the total core, which is 0.468 cm³, with the outer layer accounting for 50% and the inner layer accounting for 50%, about 0.234 cm³ for each layer. Assuming that the anchor rod is 12 m long and 5 cm in diameter, and one branch is arranged every 30 cm in height, then there are 40 branches; a circle of hierarchical repair units is arranged every 15 cm in height, with 80 circles; there are 2 secondary bifurcated rods 122, and there are 3 hierarchical repair units on one secondary bifurcated rod 122, so there are 6 hierarchical repair units on one primary bifurcated rod 121, 8 are arranged in one circumference on the main anchor rod 11, a total of 6×40 + 8×80 = 880 are arranged, and a total of 880×0.468 = 411.84 cm³, of which the total volume of the outer layer repair units is about 205 cm³.

[0061] It should be understood that the present invention is not limited in its application to the detailed construction and arrangement of components set forth herein. The present invention is capable of other embodiments and of being practiced and carried out in various ways. The foregoing variations and modifications fall within the scope of the present invention. It should be understood that the invention as disclosed and defined herein extends to all alternative combinations of two or more separate features mentioned or evident in the text and / or drawings. All such different combinations constitute various alternative aspects of the present invention. The embodiments described herein illustrate the best mode known for practicing the invention and will enable those skilled in the art to utilize the invention.

Claims

1. A self - repairing support system for altered surrounding rock in a pumped - storage power station, characterized in that, Comprising: A fractal anchoring structure, including a main anchor rod and a plurality of multi-stage bifurcated anchor rods arranged along the length extension direction of the main anchor rod. A grouting main pipe is arranged inside the main anchor rod, and grouting branch pipes are arranged inside the multi-stage bifurcated anchor rods. The grouting main pipe and the grouting branch pipes are communicated; A number of hydraulic gradient response type hierarchical repair structures, evenly distributed on the main anchor rod and the multi-stage bifurcated anchor rods; Wherein, the hydraulic gradient response type hierarchical repair structure at least includes a first-level repair unit. The first-level repair unit includes a first repair agent and a first pressure trigger film wrapping the first repair agent. When the seepage pressure in the altered surrounding rock reaches the first threshold value, the first pressure trigger film ruptures to release the first repair agent to fill the crack.

2. The self - repairing support system for altered surrounding rock in a pumped - storage power station according to claim 1, characterized in that, Each of the multi-stage bifurcated anchor rods at least includes: A first-level bifurcated rod, inclined on the main anchor rod, having a first included angle with the main anchor rod; A second-level bifurcated rod, inclined on the first-level bifurcated rod, having a second included angle with the first-level bifurcated rod.

3. The self - repairing support system for altered surrounding rock in a pumped - storage power station according to claim 2, characterized in that, The first-level bifurcated rods are arranged at intervals along the length extension direction of the main anchor rod, and the positions of adjacent first-level bifurcated rods are staggered at intervals of greater than or equal to 90° in the circumferential direction of the main anchor rod.

4. The self - repairing support system for altered surrounding rock in a pumped - storage power station according to claim 1, characterized in that, The main anchor rod includes a central chamber and an outer chamber between the central chamber and the outer wall; The self-repairing support system for the altered surrounding rock of the pumped storage power station further includes a drain pipe; Wherein, the grouting main pipe is arranged in the central chamber, and the drain pipe is arranged in the outer chamber for draining the water in the altered surrounding rock.

5. The self - repairing support system for altered surrounding rock in a pumped - storage power station according to claim 4, characterized in that, There are a plurality of the drain pipes, and the plurality of drain pipes are arranged in an array in the outer chamber.

6. The self - repairing support system for altered surrounding rock in a pumped - storage power station according to claim 4, characterized in that, A number of grouting holes are also arranged on the main anchor rod. The grouting holes communicate the grouting main pipe and the outside of the fractal anchoring structure, so that the grout can enter the anchor rod hole through the grouting holes.

7. The self - repairing support system for altered surrounding rock in a pumped - storage power station according to claim 1, characterized in that, The hydraulic gradient response type hierarchical repair structure further includes a second-level repair unit located inside the first pressure trigger film. The second-level repair unit includes a second repair agent and a second pressure trigger film wrapping the second repair agent. When the seepage pressure in the altered surrounding rock reaches the second threshold value, the second pressure trigger film ruptures to release the second repair agent to fill the crack.

8. The self - repairing support system for altered surrounding rock in a pumped - storage power station according to claim 7, characterized in that, The first repair agent and / or the second repair agent is a silicate-nano bentonite composite repair agent. After the first pressure trigger film and / or the second pressure trigger film rupture to release the repair agent, nano-silica gel is formed.

9. The self - repairing support system for altered surrounding rock in a pumped - storage power station according to claim 1, characterized in that, A number of circles of hydraulic gradient response type hierarchical repair structures are arranged on the main anchor rod, and each circle includes a plurality of the hydraulic gradient response type hierarchical repair structures.

10. The self - repairing support system for altered surrounding rock in a pumped - storage power station according to any one of claims 1 - 9, characterized in that, The volume of the altered zone that the self-repairing support system for the altered surrounding rock of the pumped storage power station can repair satisfies: It is directly proportional to the volume percentage of the first repair agent and / or the second repair agent in the core of the first-level repair unit and / or the second-level repair unit, the volume of the core of the first-level repair unit and / or the second-level repair unit, the total length of the main anchor rod, the number of arrangements of the hydraulic gradient response type hierarchical repair structures on a single second-level bifurcated rod, and the number of arrangements of the hydraulic gradient response type hierarchical repair structures in a circle along the circumferential direction of the main anchor rod, and is inversely proportional to the arrangement spacing of the first-level bifurcated rods along the main anchor rod and the arrangement spacing of the hydraulic gradient response type hierarchical repair structures along the main anchor rod.

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