Composite pre-pressing structure and system for reinforcing broken fault zone and reinforcing method

Abstract

The invention relates to an underground engineering rock mass reinforcing technology, and discloses a composite pre-pressing structure, a composite pre-pressing system and a reinforcing method for reinforcing a broken fault zone. The composite pre-pressing structure is used for reinforcing a pressure chamber located in a fault fracture zone, the fault fracture zone is located between two complete bed rocks, and the composite pre-pressing structure comprises a plurality of concrete plugs and pre-stressed anchor cables. Each concrete plug is of a wedge-shaped structure and is transversely embedded into a fault fracture zone, the width of one end, close to the pressure chamber, of each concrete plug is larger than that of the other end of each concrete plug, and a pre-stressed anchor hole is formed in each concrete plug. The pre-stressed anchor cable penetrates through the fault fracture zone at a preset inclination angle, the head end of the pre-stressed anchor cable is locked in the pre-stressed anchor hole, and the tail end of the pre-stressed anchor cable is fixed in the complete bed rock mass. Through the synergistic effect of the wedge-shaped concrete plug and the pre-stressed anchor cable in multiple directions, the shear strain of a fault fracture zone and a complete bedrock interface is remarkably reduced.

Description

Technical Field

[0001] The present invention relates to underground engineering rock mass reinforcement technology, in particular to a composite preloading structure, a composite preloading system and a reinforcement method for reinforcing a broken fault zone. Background Art

[0002] Currently, the construction of high-pressure underground chambers, such as compressed air energy storage, hydropower stations, and nuclear power plants, often involves crossing fault zones due to tectonic activity. The complex geological conditions in these areas pose a serious threat to project stability and directly impact project safety.

[0003] Currently, the industry generally uses passive reinforcement technology combining prestressed anchors with grouting. This technology involves drilling holes, embedding anchors, and injecting grout to seal fractures, thereby enhancing the integrity and bearing capacity of the fault zone. This method has achieved some success in repairing low-stress fractured rock masses, but it still faces technical bottlenecks under high-pressure and extreme working conditions.

[0004] When a large-scale fault fracture zone exists outside the concrete lining, the significant difference in stiffness between the fracture zone and the intact bedrock creates a strong stress gradient at the interface during the combined forces between the two. Under the continuous action of high internal pressure, the shear strain at the interface between the fracture zone and the intact bedrock increases dramatically, causing progressive shear slip along the interface, ultimately leading to circumferential shear failure of the lining layer, which in turn triggers a series of problems such as leakage of high-pressure media and seepage instability of the surrounding rock.

[0005] Therefore, how to reduce the shear strain at the interface between the fracture zone and the intact bedrock has become a technical problem that needs to be solved urgently. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: how to reduce the shear strain at the interface between the fracture zone and the intact bedrock.

[0007] In order to solve the above technical problems, the present invention provides a composite preloading structure, a composite preloading system and a reinforcement method for reinforcing a broken fault zone.

[0008] According to a first aspect of the present invention, a composite prestressing structure for reinforcing a broken fault zone is provided. The composite prestressing structure is used to reinforce a pressure chamber in a fault fracture zone. The fault fracture zone is located between two intact bedrocks. The composite prestressing structure comprises: a plurality of concrete plugs. The concrete plugs are wedge-shaped structures. The plurality of concrete plugs are laterally embedded in the fault fracture zone. The width of the concrete plug at one end close to the pressure chamber is greater than the width at the other end. A prestressed anchor hole is provided in the concrete plug; a prestressed anchor cable. The prestressed anchor cable passes through the fault fracture zone at a preset inclination angle. The head end of the prestressed anchor cable is locked in the prestressed anchor hole, and the end of the prestressed anchor cable is fixed in the intact bedrock body.

[0009] In one embodiment, an adjustable tensioning device is provided on the head end of the prestressed anchor cable, and the prestressed anchor cable is locked in the prestressed anchor hole through the adjustable tensioning device.

[0010] In one embodiment, a grouting channel is further provided in the concrete plug, through which grouting is injected into the fault fracture zone. After the slurry solidifies, a grouting reshaping body with a serrated interlocking structure on the surface of the concrete plug is formed. The grouting reshaping body is used to resist the lining pressure of the pressure chamber.

[0011] In one embodiment, the composite prestressing structure further includes an H-shaped steel, which is placed transversely in the fault fracture zone, and one end of the H-shaped steel abuts against the concrete plug.

[0012] In one embodiment, a shear key is provided on the H-shaped steel, and the shear key is fixed to the H-shaped steel in the vertical direction, thereby improving the efficiency of force transmission from the H-shaped steel to the grouting reshaped body.

[0013] The second aspect of the present invention provides a composite prestressing system for reinforcing a broken fault zone, comprising: two intact bedrocks with a fault fracture zone distributed between the two intact bedrocks; a pressure chamber, the pressure chamber being in the fault fracture zone; and the composite prestressing structure provided by the first aspect of the present invention, the composite prestressing structure being fixed between the pressure chamber and the intact bedrock.

[0014] The third aspect of the present invention provides a reinforcement method for a broken fault zone, comprising: S1, excavating intact bedrock to the plane where the broken fault zone is located, pouring wedge-shaped concrete plugs on both sides of the pressure chamber, and reserving prestressed anchor holes in the concrete plugs; S2, drilling an inclined channel in the intact bedrock along the inclination direction of the broken fault zone; S3, inserting the end of the prestressed anchor cable into the inclined channel, and inserting the head end of the prestressed anchor cable into the prestressed anchor hole.

[0015] In one embodiment, an adjustable tensioning device is provided on the head end of the prestressed anchor cable, and the prestressed anchor cable is locked in the prestressed anchor hole through the adjustable tensioning device. After step S3, the reinforcement method further includes: S4, adjusting the tension or pulling force of the prestressed anchor cable.

[0016] In one embodiment, in step S1, when pouring concrete plugs with a wedge-shaped structure on both sides of the pressure chamber, grouting channels are also reserved in the concrete plugs. After step S4, the reinforcement method further includes: S5, grouting into the fault fracture zone through the grouting channels, and forming a grouting reshaping body with a serrated interlocking structure with the surface of the concrete plug after the slurry solidifies; and S6, applying prestress to the grouting reshaping body in stages.

[0017] In one embodiment, between step S2 and step S3, the reinforcement method further includes: S7, implanting an H-shaped steel in the fault fracture zone, and placing one end of the H-shaped steel in contact with the concrete plug.

[0018] Compared with the prior art, the composite preloading structure, composite preloading system, and reinforcement method for reinforcing a fractured fault zone according to the embodiment of the present invention have the following beneficial effects:

[0019] The composite prestressing structure of this invention significantly reduces shear strain at the interface between the fault fracture zone and intact bedrock through the synergistic effect of a wedge-shaped concrete plug and prestressed anchor cables. Specifically, the wedge-shaped concrete plug is transversely embedded within the fault fracture zone. Its wide end, located near the pressure chamber, utilizes a wedging effect to enhance lateral restraint within the fault fracture zone, effectively dissipating interfacial stress.

[0020] Furthermore, the prestressed anchor cable penetrates the fault fracture zone at a preset inclination angle and is anchored in the intact bedrock. The fault fracture zone and the intact bedrock are clamped by actively applied prestress, forming a compressive stress zone at the interface, and converting the shear load into compressive stress conduction.

[0021] At the same time, the inclined arrangement of the prestressed anchor cables can synergistically resist shear in the XY direction and degassing deformation in the Z direction. The combination of the two enables the fault fracture zone and the intact bedrock to form an integrated force system, reducing stress concentration caused by stiffness differences, thereby reducing shear strain at the interface between the fracture zone and the intact bedrock, and reducing the progressive shear slip of the lining structure along the interface between the fault fracture zone and the intact bedrock. This improves the structural stability of the high-pressure pressure chamber in the fault fracture zone and effectively prevents engineering risks such as leakage of high-pressure media and instability of the surrounding rock due to seepage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of a composite preloading system exemplarily shown in an embodiment of the present invention.

[0023] Figure 2 The figure is a schematic diagram of the installation of H-beam in a composite preloading system exemplarily shown in an embodiment of the present invention.

[0024] Figure 3 It is a structural schematic diagram of a composite pre-pressing structure exemplarily shown in an embodiment of the present invention.

[0025] Figure 4 It is a schematic structural diagram of an H-shaped steel according to an embodiment of the present invention.

[0026] Figure 5 1 is a graph showing the relationship between the preload pressure and bulk modulus of a fault fracture zone, as exemplified in an embodiment of the present invention.

[0027] Figure 6 It is a flow chart of a construction method of a composite prestressed structure exemplarily shown in an embodiment of the present invention.

[0028] Reference numerals:

[0029] 1. Composite preloading system, 10. Composite preloading structure, 11. Fault fracture zone, 12. Pressure chamber, 13. Intact bedrock, 101. Several concrete plugs, 102. Prestressed anchor cables, 1011. Grouting channel, 103. H-shaped steel, 1031. Shear key, 104. Adjustable tensioning device. DETAILED DESCRIPTION

[0030] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0031] In the description of the present invention, it should be understood that the term "intact bedrock" used in the present invention refers to the rock area into which the pile foundation can penetrate, and the rock area has no cracks, joints or weathering phenomena and has good bearing capacity. The term "lining pressure" in the present invention refers to the sum of various loads acting on the pressure chamber lining structure, including surrounding rock pressure, internal water pressure, tectonic stress, etc., which can cause deformation, cracking and even shear failure of the lining structure, and is the key force that the reinforcement technology of the present invention focuses on.

[0032] The construction of high-pressure underground chambers, such as compressed air energy storage, hydropower stations, and nuclear power plants, often involves crossing fault zones due to tectonic activity. The complex geological conditions in these areas pose a serious threat to project stability and directly impact project safety.

[0033] Currently, the industry generally uses passive reinforcement technology combining prestressed anchors with grouting. This technology involves drilling holes, embedding anchors, and injecting grout to seal fractures, thereby enhancing the integrity and bearing capacity of the fault zone. This method has achieved some success in repairing low-stress fractured rock masses, but it still faces technical bottlenecks under high-pressure and extreme working conditions.

[0034] When a large-scale fault fracture zone exists outside the concrete lining, the significant difference in stiffness between the fracture zone and the intact bedrock creates a strong stress gradient at the interface during the combined forces between the two. Under the continuous action of high internal pressure, the shear strain at the interface between the fracture zone and the intact bedrock increases dramatically, causing progressive shear slip along the interface, ultimately leading to circumferential shear failure of the lining layer, which in turn triggers a series of problems such as leakage of high-pressure media and seepage instability of the surrounding rock.

[0035] Therefore, how to reduce the shear strain at the interface between the fracture zone and the intact bedrock has become a technical problem that needs to be solved urgently.

[0036] For this reason, Figure 1-3As shown, a preferred embodiment of an embodiment of the present invention is a composite prestressing structure 10 for reinforcing a broken fault zone. The composite prestressing structure 10 is used to reinforce a pressure chamber 12 in a fault fracture zone 11. The fault fracture zone 11 is between two intact bedrocks 13. The composite prestressing structure 10 includes: a number of concrete plugs 101 and prestressed anchor cables 102.

[0037] The concrete plugs are wedge-shaped, with several concrete plugs 101 transversely embedded within the fault fracture zone 11. The width of the concrete plugs near the pressure chamber 12 is greater than that of the other end. Prestressed anchor holes are provided within the concrete plugs. Prestressed anchor cables 102 penetrate the fault fracture zone 11 at a preset inclination angle. The head ends of the prestressed anchor cables 102 are locked in the prestressed anchor holes, while the tail ends of the prestressed anchor cables 102 are fixed to the intact bedrock 13.

[0038] Through the above-described solution, the composite prestressing structure 10 of the present invention significantly reduces the shear strain at the interface between the fault fracture zone 11 and the intact bedrock 13 through the synergistic effect of the wedge-shaped concrete plug and the prestressed anchor cable 102. Specifically, the wedge-shaped concrete plug is transversely embedded in the fault fracture zone 11. Its wide end near the pressure chamber 12 utilizes a wedging effect to enhance the lateral constraint on the fault fracture zone 11, effectively dissipating the interfacial stress.

[0039] Furthermore, the prestressed anchor cable 102 penetrates the fault fracture zone 11 at a preset inclination angle and is anchored in the intact bedrock 13. The fault fracture zone 11 and the intact bedrock 13 are clamped together by the actively applied prestress, forming a compressive stress zone at the interface. This compressive stress effectively fills the cracks and voids in the fracture zone by pre-compressing the crushed rock mass, significantly improving the density of the crushed rock mass, thereby increasing the bulk modulus of the fracture zone (i.e., enhancing the ability of the rock mass to resist volume deformation). The relationship between pre-compression force and bulk modulus is shown in the figure below: Figure 5 shown.

[0040] This mechanism improves the mechanical properties of the fracture zone through the sustained compressive stress field created by prestressing, transforming it from a loose, low-rigidity medium into a composite structure with a higher load-bearing capacity, providing active reinforcement for the engineering rock mass. The inclined prestressed anchor cable 102 has an exemplary inclination angle of 15 to 45 degrees.

[0041] At the same time, the inclined arrangement of the prestressed anchor cables 102 can synergistically resist shear in the XY direction and degassing deformation in the Z direction. The combination of the two allows the fault fracture zone 11 and the intact bedrock 13 to form an integrated force-bearing system, reducing stress concentration caused by stiffness differences. This, in turn, reduces shear strain at the interface between the fracture zone and the intact bedrock 13, and reduces the progressive shear slip of the lining structure along the interface between the fault fracture zone 11 and the intact bedrock 13. This improves the structural stability of the high-pressure pressure chamber 12 in the fault fracture zone 11, effectively preventing engineering risks such as leakage of high-pressure media and instability of the surrounding rock due to seepage.

[0042] Moreover, in one embodiment of the present application, Figure 3 As shown, an adjustable tensioning device 104 is provided on the head end of the prestressed anchor cable 102 , and the prestressed anchor cable 102 is locked in the prestressed anchor hole through the adjustable tensioning device 104 .

[0043] The adjustable tensioning device 104 at the head end of the prestressed anchor cable 102 further enhances the reinforcement performance and applicability of the composite prestressed structure 10. This device dynamically adjusts the anchor cable tension in real time based on the actual stress on the fault fracture zone 11 and monitoring data, precisely controlling the interfacial stress between the fault fracture zone 11 and the intact bedrock 13, effectively addressing the problem of prestress attenuation caused by complex geological conditions.

[0044] At the same time, the adjustable tensioning device enables graded application of prestress through prestressed anchor cables 102, achieving progressive control of the stress at the interface between the fracture zone 11 and the intact bedrock 13. During the initial construction phase, a low prestress can be applied to prevent localized instability in the fracture zone due to sudden stress changes. As the concrete plug strength increases and the stress in the surrounding rock gradually releases, the prestress is increased in stages, achieving dynamic equilibrium between the reinforced structure and the surrounding rock. This graded loading method also effectively reduces the risk of anchor cable relaxation caused by excessive single tensioning stress, ensuring long-term, stable prestress at the interface.

[0045] Conventional anchor bolts are subjected to point-loaded forces, with stress transmitted along the limited bonded sections of the bolt. The shear stress paths within the intact bedrock 13 are randomly discrete, forming discontinuous force transmission channels within the fault fracture zone 11. Under shear load, stress waves reflect between discrete nodes, with energy concentrated in unreinforced areas (such as grouting fractures), triggering shear through-zones. This energy is the elastic potential energy within the rock mass when the shear load acts on it, as well as the kinetic energy carried by the stress wave.

[0046] In an embodiment of the present invention, a grouting channel 1011 may be further provided in the concrete plug, through which grouting is injected into the fault fracture zone 11 . After the slurry solidifies, a grouting reshaping body with a serrated interlocking structure on the surface of the concrete plug is formed. The grouting reshaping body is used to resist the lining pressure of the pressure chamber 12 .

[0047] Leveraging the properties of slurry, high-pressure cement slurry injected through grouting channel 1011 effectively fills the fissures and pores within fault fracture zone 11, cementing the loose, broken rock blocks into a single piece and enhancing the shear strength of the rock mass. Since the fissures and pores within fault fracture zone 11 are filled and reduced, the grouting fracture surface is correspondingly reduced or even eliminated, making it difficult to form a concentrated energy release, and thus, the formation of a shear penetration zone.

[0048] The sudden change in stiffness between the fault fracture zone and the intact bedrock causes the lining stress to concentrate at the interface, which can easily lead to structural damage. In the present invention, the solidified slurry is tightly engaged with the serrated structure on the surface of the concrete plug. The grouting remodeling body penetrates the cracks in the fracture zone through cement slurry or chemical slurry, significantly expanding the contact area between the concrete plug and the fracture zone, while increasing the elastic modulus of the fracture zone, forming a stiffness gradient transition system of "bedrock-grouting remodeling body-fracture zone". This composite structure changes the transmission path of the lining pressure, allowing the shear stress originally concentrated at the interface to be dispersed to a larger range of the "slurry-rock" complex. Through the collaborative load-bearing of the skeleton-filling structure inside the remodeling body, the stress concentration coefficient is effectively reduced, thereby improving the stability and durability of the lining structure.

[0049] This dual effect of "grouting filling + interlocking anchoring" not only enhances the bearing capacity of the fault fracture zone 11 itself, but also significantly reduces the risk of shear damage to the interface caused by lining pressure, further ensuring the safe and stable operation of the pressure chamber 12 under complex geological conditions.

[0050] In another embodiment of the present invention, Figure 2 As shown, the composite prestressing structure 10 may further include an H-shaped steel 103 , which is horizontally placed in the fault fracture zone 11 , with one end of the H-shaped steel 103 abutting against the concrete plug.

[0051] The H-shaped steel 103 is placed horizontally in the fault fracture zone 11, with one end abutting against the concrete plug. On the one hand, it plays the role of a "rigid skeleton", significantly improving the shear resistance of the fault fracture zone 11.

[0052] On the other hand, the H-shaped steel 103 works synergistically with the concrete plug to form a support system. The concrete plug uses the wedge structure and grouting reshaping body to provide flexible constraints, while the H-shaped steel 103 uses rigid support to limit the deformation of the broken zone. The two complement each other and effectively suppress the relative sliding of the interface between the broken zone and the intact bedrock 13.

[0053] In addition, the presence of the H-shaped steel 103 can also guide the uniform conduction of stress, avoid local excessive stress causing rock damage, thereby further enhancing the overall stability of the pressure chamber 12 in the fault fracture zone 11, and providing more reliable protection for resisting the lining pressure under complex working conditions.

[0054] In order to further improve the conduction effect, in one embodiment of the present application, Figure 4 As shown, a shear key 1031 is provided on the H-shaped steel 103, and the shear key 1031 is fixed on the H-shaped steel 103 along the vertical direction to improve the force transmission efficiency of the H-shaped steel 103 to the grouting reshaped body.

[0055] The shear keys 1031 vertically fixed on the upper edge of the H-shaped steel 103 increase the contact area and bite strength between the H-shaped steel 103 and the grouting reshaping body, thereby more efficiently transmitting external forces such as lining pressure and shear load to the reinforced structure composed of the grouting reshaping body and the concrete plug. In other words, the force transmission efficiency of the H-shaped steel 103 to the grouting reshaping body is improved, the relative slip between the H-shaped steel 103 and the surrounding rock mass is reduced, and the stress concentration phenomenon is effectively reduced.

[0056] The shear key 1031 works synergistically with the H-shaped steel 103 and the grouting remodeling body to form a stable force transmission system, ensuring that the fault fracture zone 11 can maintain structural stability under complex stress conditions.

[0057] The various embodiments of the present invention can be used in combination. For example, during the construction of an underground chamber at a hydropower station, it was discovered that a broken fault zone was crossed, and the rock quality grade was poor (RQD>25%). The rock mass within the fault zone was loose and broken, with poor self-stabilization ability, unable to provide effective support for the subsequent concrete lining. There was also a significant risk of shear slip, endangering the overall stability of the chamber. To address the above problem, the composite preloading structure 10 proposed in the present invention can be used.

[0058] Since the quality of fault rock is related to the specific implementation plan, the relevant standard "ASTM D6032-08" is referred to and RQD (Rock Quality Designation, fault fragmentation index) is used for quantification. The formula is:

[0059]

[0060] Among them, L 10 RQD is the length of a single core greater than or equal to 10 cm that is not cut by natural fractures or fracture zones (i.e., the length of the intact rock formation), and L is the total drilling footage. When RQD is less than 25%, the rock quality grade of the corresponding fractured fault zone is extremely poor, and H-shaped steel can be added to improve the force transmission capacity of the fractured fault zone. When RQD is ≥ 25% but below the target design requirement, a single "anchor cable-concrete plug-consolidation grouting" structure can be used for reinforcement.

[0061] like Figure 5 As shown, in the present invention, the evolution curve of the compressive stress generated by the concrete plug and the bulk modulus of the broken fault zone satisfies the relationship:

[0062]

[0063] Among them, σ is the compressive stress generated by the concrete plug, K is the bulk modulus of the broken fault zone, ε is the real-time strain value of the fault, and ε0 is the initial strain value before prestressing is applied. The tensile force is dynamically adjusted through real-time monitoring data to increase the fault elastic modulus to 1.5-3 times the initial value.

[0064] Accordingly, the present invention also provides a composite prestressing system 1 for reinforcing a broken fault zone. The composite prestressing system 1 may include two complete bedrocks 13, a pressure chamber 12, and a composite prestressing structure 10 in any embodiment of the present invention.

[0065] A fault fracture zone 11 is distributed between two intact bedrocks 13 , a pressure chamber 12 is located in the fault fracture zone 11 , and a composite preloading structure 10 is fixed between the pressure chamber 12 and the intact bedrock 13 .

[0066] The composite preloading system 1 in the present invention includes all the technical features of the composite preloading structure 10 in the present invention, so all the embodiments and beneficial effects of the composite preloading structure 10 in the present invention are applicable to the composite preloading system 1 in the present invention.

[0067] Moreover, in order to ensure that the composite pre-pressed structure 10 that meets the technical requirements is formed, as Figure 6 As shown, the present invention also provides a reinforcement method for a broken fault zone, which may include:

[0068] S1. Excavate the intact bedrock 13 to the plane where the broken fault zone is located, cast wedge-shaped concrete plugs on both sides of the pressure chamber 12, and reserve prestressed anchor holes in the concrete plugs.

[0069] S2. Drill an oblique tunnel in the intact bedrock 13 along the fractured fault zone in the dip direction.

[0070] S3. Insert the end of the prestressed anchor cable 102 into the inclined channel, and insert the head end of the prestressed anchor cable 102 into the prestressed anchor hole.

[0071] Between the wedge-shaped concrete plugs cast on either side of the pressure chamber 12, a trapezoidal pilot tunnel can be excavated along the inclination of the fractured fault zone to expose the fractured area of ​​the fractured fault zone. Temporary steel supports are placed on both sides of the trapezoidal pilot tunnel, and drainage pipes are installed simultaneously to lower the groundwater level and prevent water seepage and softening of the fractured rock mass. After completing this initial support, low-strength shotcrete is used to seal the fracture surface, creating an initial stress relief environment.

[0072] In the present invention, a concrete plug can be excavated from the pressure chamber 12 toward the broken fault zone to form a wedge-shaped trough with a size larger than the fault section. Prestressed anchor holes and grouting channels 1011 are set up in the wedge-shaped trough using materials such as plastic pipes. Subsequently, micro-expansive concrete is poured into the trough to obtain a concrete plug with prestressed anchor holes and grouting channels 1011.

[0073] On this basis, in one embodiment of the present invention, an adjustable tensioning device 104 may be provided on the head end of the prestressed anchor cable 102, and the prestressed anchor cable 102 is locked in the prestressed anchor hole through the adjustable tensioning device 104. After step S3, the reinforcement method further includes: S4, adjusting the tension or pulling force of the prestressed anchor cable 102.

[0074] In another embodiment of the present invention, in step S1, when pouring concrete plugs with a wedge-shaped structure on both sides of the pressure chamber 12, a grouting channel 1011 is reserved in the concrete plug. After step S4, the reinforcement method further includes: S5, grouting into the fault fracture zone 11 through the grouting channel 1011, and forming a grouting reshaping body with a serrated bite structure on the surface of the concrete plug after the slurry solidifies; S6, applying prestress to the grouting reshaping body in stages.

[0075] The present invention applies prestress in stages, specifically, the initial loading can be 50% of the design value to balance the residual stress of the rock mass. The stress relaxation rate of the prestressed anchor cable 102 is monitored within 24 hours. If the relaxation rate is ≤3%, the prestress is loaded to 100% of the design value.

[0076] S5. Grouting into the fault fracture zone 11 through the grouting channel 1011 can be further divided into three stages:

[0077] Low-pressure infiltration stage: low-pressure grouting is used to fill the main fracture network.

[0078] Medium-pressure fracturing stage: The grouting pressure is increased to medium pressure, secondary cracks are expanded and tree-root-like grout veins are formed.

[0079] High-pressure compaction stage: The grouting pressure reaches a high-pressure state, compacting the remaining loose bodies in the cracks to form a dense grouting reinforcement layer.

[0080] The low pressure, medium pressure and high pressure in the present invention are only obtained based on the pressure comparison of the current exemplary construction environment, and therefore can be equivalent to any three different levels of pressure in other construction environments.

[0081] In one embodiment, between step S2 and step S3 , the reinforcement method further includes: S7 , implanting an H-shaped steel 103 in the fault fracture zone 11 , and placing one end of the H-shaped steel 103 in contact with a concrete plug.

[0082] Compared with the prior art, the composite preloading structure 10, composite preloading system 1, and reinforcement method for reinforcing a fractured fault zone according to the embodiment of the present invention have the following beneficial effects:

[0083] The composite prestressing structure 10 of the present invention significantly reduces shear strain at the interface between the fault fracture zone 11 and intact bedrock 13 through the synergistic effect of a wedge-shaped concrete plug and prestressed anchor cables 102. Specifically, the wedge-shaped concrete plug is laterally embedded within the fault fracture zone 11. Its wide end, located near the pressure chamber 12, utilizes a wedging effect to enhance lateral restraint on the fault fracture zone 11, effectively dissipating interfacial stress.

[0084] Furthermore, the prestressed anchor cable 102 penetrates the fault fracture zone 11 at a preset inclination angle and is anchored in the intact bedrock 13. The fault fracture zone 11 and the intact bedrock 13 are clamped by actively applying prestress, and the rock mass is crushed by pre-compression, thereby increasing the bulk modulus of the fracture zone.

[0085] At the same time, the inclined arrangement of the prestressed anchor cables 102 can synergistically resist shear in the XY direction and degassing deformation in the Z direction. The combination of the two allows the fault fracture zone 11 and the intact bedrock 13 to form an integrated force-bearing system, reducing stress concentration caused by stiffness differences. This, in turn, reduces shear strain at the interface between the fracture zone and the intact bedrock 13, and reduces the progressive shear slip of the lining structure along the interface between the fault fracture zone 11 and the intact bedrock 13. This improves the structural stability of the high-pressure pressure chamber 12 in the fault fracture zone 11, effectively preventing engineering risks such as leakage of high-pressure media and instability of the surrounding rock due to seepage.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A composite preloading structure for reinforcing a broken fault zone, characterized in that: The composite preloading structure (10) is used to reinforce a pressure chamber (12) located in a fault fracture zone (11), wherein the fault fracture zone (11) is located between two intact bedrocks (13). The composite preloading structure (10) comprises: A plurality of concrete plugs (101), each of the concrete plugs being a wedge-shaped structure, and being laterally embedded in the fault fracture zone (11), wherein the width of one end of the concrete plug close to the pressure chamber (12) is greater than the width of the other end, and wherein a prestressed anchor hole is provided in the concrete plug; A prestressed anchor cable (102) is provided, wherein the prestressed anchor cable (102) penetrates the fault fracture zone (11) at a preset inclination angle, the head end of the prestressed anchor cable (102) is locked in the prestressed anchor hole, and the tail end of the prestressed anchor cable (102) is fixed in the intact bedrock (13).

2. The composite pre-compression structure according to claim 1, characterized in that: An adjustable tensioning device (104) is provided on the head end of the prestressed anchor cable (102), and the prestressed anchor cable (102) is locked in the prestressed anchor hole through the adjustable tensioning device (104).

3. The composite pre-compression structure according to claim 1, characterized in that: A grouting channel (1011) is further provided in the concrete plug, through which grouting is injected into the fault fracture zone (11). After the grouting solidifies, a grouting reshaping body with a serrated bite structure on the surface of the concrete plug is formed, and the grouting reshaping body is used to resist the lining pressure of the pressure chamber (12).

4. The composite pre-compression structure according to claim 3, characterized in that: The composite prestressing structure (10) further comprises an H-shaped steel (103), wherein the H-shaped steel (103) is horizontally placed in the fault fracture zone (11), and one end of the H-shaped steel (103) abuts against the concrete plug.

5. The composite pre-compression structure according to claim 4, characterized in that: A shear key (1031) is provided on the H-shaped steel (103), and the shear key (1031) is fixed to the H-shaped steel (103) in the vertical direction, thereby improving the efficiency of force transmission from the H-shaped steel (103) to the grouting reshaped body.

6. A composite preloading system for reinforcing a broken fault zone, characterized in that: include: Two intact bedrocks (13), with a fault fracture zone (11) distributed between the two intact bedrocks (13); a pressure chamber (12), wherein the pressure chamber (12) is located in the fault fracture zone (11); The composite preloading structure (10) according to any one of claims 1 to 5, wherein the composite preloading structure (10) is fixed between the pressure chamber (12) and the intact bedrock (13).

7. A reinforcement method for a broken fault zone, characterized in that: include: S1, excavating the intact bedrock (13) to the plane where the broken fault zone is located, pouring wedge-shaped concrete plugs on both sides of the pressure chamber (12), and reserving prestressed anchor holes in the concrete plugs; S2, drilling an oblique tunnel in the intact bedrock (13) along the fractured fault zone in the dipping direction; S3, inserting the end of the prestressed anchor cable (102) into the inclined channel, and inserting the head end of the prestressed anchor cable (102) into the prestressed anchor hole.

8. The reinforcement method according to claim 7, characterized in that: An adjustable tensioning device (104) is provided on the head end of the prestressed anchor cable (102), and the prestressed anchor cable (102) is locked in the prestressed anchor hole by the adjustable tensioning device (104). After step S3, the reinforcement method further comprises: S4. Adjust the tension or pulling force of the prestressed anchor cable (102).

9. The reinforcement method according to claim 8, characterized in that: In step S1, when pouring concrete plugs of a wedge-shaped structure on both sides of the pressure chamber (12), a grouting channel (1011) is reserved in the concrete plugs. After step S4, the reinforcement method further includes: S5, injecting grout into the fault fracture zone (11) through the grouting channel (1011), and forming a grouting remodeling body with a serrated bite structure on the surface of the concrete plug after the grouting solidifies; S6. Applying prestress to the grouting reshaped body in stages.

10. The reinforcement method according to claim 9, characterized in that: Between step S2 and step S3, the reinforcement method further includes: S7. Implant an H-shaped steel (103) in the fault fracture zone (11), and place one end of the H-shaped steel (103) in contact with the concrete plug.

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