Pressure self-balancing tunnel lining surrounding rock composite damping structure and pressure self-balancing method

Abstract

The invention belongs to the anti-seismic field of underground engineering, and particularly discloses a pressure self-balancing tunnel lining surrounding rock composite damping structure and a pressure self-balancing method.The structure comprises a composite damping layer, and the composite damping layer comprises a surrounding rock contact layer close to the side of surrounding rock and a lining contact layer close to the side of a lining; the surrounding rock contact layer is made of a high-damping rubber-basalt fiber composite material and is pre-pressed and embedded into a surrounding rock crack; the lining contact layer is made of a composite viscoelastic material in which flexible capsules are uniformly embedded; the flexible capsule body is of an upper-lower double-layer structure composed of an upper capsule body and a lower capsule body, and the upper capsule body and the lower capsule body are filled with non-Newtonian fluid. A storage bag is arranged on one side of the lower-layer bag body and is separated from the other part of the lower-layer bag body; and one-way hydraulic valves are arranged between the upper-layer bag body and the lower-layer bag body and between the storage bag and the lower-layer bag body. The force balance between the surrounding rock and the lining can be adjusted according to the pressure designed in advance, and deformation coordination among the surrounding rock, the buffer layer and the lining is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underground engineering anti-seismic, in particular to a pressure self-balancing tunnel lining surrounding rock composite damping structure and a pressure self-balancing method, which is suitable for the lining damping system of a deep buried water conveying tunnel under the combined action of high ground stress, high internal water pressure and seismic motion. BACKGROUND

[0002] Long distance deep buried water conveying tunnels inevitably face the risk of high ground stress, high internal water pressure and seismic action. At present, the main methods for damping are damping layer and surrounding rock grouting reinforcement, among which the damping layer mainly sets a flexible material layer (such as foam concrete) between the lining and the surrounding rock to reduce the seismic stress, which is especially suitable for hard surrounding rock tunnel sections; the surrounding rock grouting mainly reinforces the surrounding rock (range 3-9m) in the fault area through grouting, which can reduce the lateral deformation of the lining. The larger the grouting range, the more significant the damping effect, which is particularly effective for soft soil tunnels. For the problem of high internal water pressure, there are mainly two ways of composite lining and drainage pressure reduction, one of which is a composite lining structure of "water blocking and permeation reduction, drainage pressure reduction", which adds a water collection layer between the surrounding rock and the lining to reduce the lateral load of the lining under external water pressure; the second is to set a concentrated drainage hole or a water diversion pipe in the high external water tunnel section to reduce the lateral pressure of the lining caused by rock water seepage. The existing technical means and measures are difficult to resist the surrounding rock damage caused by high ground stress, the lining expansion and cracking caused by high internal water pressure, and the shear failure of the lining-surrounding rock interface caused by seismic motion. SUMMARY

[0003] In view of the above situation, in order to overcome the defects of the existing rigid concrete backfill or ordinary elastic cushion in the long distance water conveying tunnel in the high seismic risk area and through the active fault zone, the purpose of the present application is to provide a pressure self-balancing tunnel lining surrounding rock composite damping structure, which can solve the long-term stability problem of the existing water conveying tunnel under the combined action of high ground stress, high internal water pressure and seismic motion.

[0004] Another purpose of the present application is to provide a pressure self-balancing method, which is equivalent to setting a buffer layer between the surrounding rock and the lining. This buffer layer can adjust the force balance between the surrounding rock and the lining according to the designed pressure, which is beneficial to the deformation coordination between the surrounding rock, the buffer layer and the lining, and can effectively avoid the extrusion of the lining by high ground stress and the extrusion of the surrounding rock by high water pressure.

[0005] In order to further realize the above purpose, the present application adopts the following technical scheme:

[0006] The tunnel lining surrounding rock composite damping structure is characterized in that: a composite damping layer is arranged between the surrounding rock and the lining, the composite damping layer comprises a surrounding rock contact layer close to the surrounding rock and a lining contact layer close to the lining; the surrounding rock contact layer is a high-damping rubber-basalt fiber composite material, and is pre-pressed and embedded into the surrounding rock fissure; the lining contact layer is a composite viscoelastic material uniformly embedded with flexible capsules;

[0007] The flexible capsule is composed of an upper capsule and a lower capsule in a double-layer structure, and the upper capsule and the lower capsule are filled with non-Newtonian fluid; one side of the lower capsule is provided with a reserve capsule, and the reserve capsule is separated from the rest of the lower capsule; a one-way hydraulic valve is arranged between the upper capsule and the lower capsule and between the reserve capsule and the lower capsule; and a total valve is further arranged at the end of the lower capsule away from the reserve capsule.

[0008] Optionally, the material of the flexible capsule is polyurethane-Kevlar composite material, and the upper limit of pressure bearing of a single flexible capsule is 60 MPa; the flexible capsule is arranged at the same height as the lining contact layer; and the non-Newtonian fluid is SiO2-polyethylene glycol suspension.

[0009] Optionally, a pressure sensor is arranged at each one-way hydraulic valve, and the pressure in the upper and lower capsules is adjusted by sensing the surrounding rock pressure and the lining pressure until the pressure balance is reached.

[0010] Optionally, along the transverse and longitudinal directions of the tunnel, the flexible capsule is arranged at a distance of 1 / 2-1L, and L is the side length of the flexible capsule; the upper and lower capsules are square and have arc-shaped edges, and the side length is 40-50 cm; and the reserve capsule accounts for 1 / 3 of the area of the lower capsule.

[0011] Optionally, the flexible capsule is connected to the lining through chemical anchors.

[0012] Optionally, the high-damping rubber-basalt fiber composite material is composed of the following raw materials in parts by weight: rubber matrix: 50-70 parts; basalt fiber: 10-30 parts; and compounding agent: 5-10 parts; wherein:

[0013] The rubber matrix comprises hydrogenated nitrile rubber and epoxidized eucommia rubber, and the mass ratio of the two is 1:1; the compounding agent comprises vulcanizing agent, reinforcing agent, antioxidant, and accelerator, and the mass ratio of the vulcanizing agent, reinforcing agent, antioxidant, and accelerator is 1:1.

[0014] Further, the preparation method of the high-damping rubber-basalt fiber composite material comprises the following steps:

[0015] Step 1, basalt fiber pretreatment: soak and clean 3-5 times with distilled water, dry at 80℃ for 3 hours after cleaning for standby; slowly add silane coupling agent to the cleaned basalt fiber and stir for 6 hours, the mass ratio of silane coupling agent to basalt fiber is 3:100, after the reaction is completed, wash the unreacted silane coupling agent with ethanol / deionized water, and finally dry at 80-120℃ for 1-3 hours to solidify;

[0016] Step 2, rubber mixing: plasticize the rubber matrix at 40-60℃, add the pretreated basalt fiber and the compounding agent, and mix in the internal mixer for 4 minutes, the temperature is ≤60℃;

[0017] Step 3, vulcanization molding: put the mixed rubber into the mold, vulcanize at 170℃ and 10MPa pressure for 20 minutes.

[0018] Alternatively, the high-damping butyl rubber-polyurethane-silicon dioxide hybrid material is composed of the following raw materials by weight: butyl rubber: 100 parts; polyurethane elastomer: 30-50 parts; silicon dioxide: 20-40 parts; vulcanizing agent: 2-5 parts; coupling agent: 1-3 parts; antioxidant: 2-5 parts.

[0019] Further, the preparation method of the high-damping butyl rubber-polyurethane-silicon dioxide hybrid material adopts a blending process, including the following steps:

[0020] Step 1, mixing stage: plasticize butyl rubber and polyurethane elastomer in an internal mixer, the temperature is 80-100℃, add the antioxidant and mix evenly;

[0021] Step 2, filler dispersion: add silicon dioxide and coupling agent in batches to ensure uniform dispersion, the rotation speed is 40-60rpm;

[0022] Step 3, vulcanization molding: transfer to an open mill and add a vulcanizing agent, then thin pass out a sheet and mold vulcanize, the temperature is 150-160℃, the pressure is 10-15MPa, and the time is 20-30 minutes.

[0023] Correspondingly, the application also provides a pressure self-balancing method, which adopts the pressure self-balancing tunnel lining surrounding rock composite damping structure, and includes:

[0024] High ground stress compensation: after the excavation of the chamber, the stress of the surrounding rock is released, the surrounding rock deforms and starts to extrude the composite damping layer between the lining and the surrounding rock, the upper layer of the flexible capsule starts to bear pressure, assuming that the design value of the surrounding rock pressure is P0, the upper limit value of the pressure borne by the upper layer of the capsule is set as P s As long as the external pressure is greater than P s , the fluid in the upper layer of the capsule flows into the reserve capsule of the lower layer of the capsule through the upper→lower one-way hydraulic valve, because the confining pressure is unloaded from P0 to Ps When the surrounding rock is still in the elastic stable deformation stage, the P s pressure is balanced with the surrounding rock pressure;

[0025] Internal water pressure balance: when the upper layer of the capsule and the surrounding rock pressure reach equilibrium, according to the principle of force transmission, the pressure between the lower layer of the flexible capsule and the lining is also P s , the upper limit of the pressure borne by the lower layer of the capsule is set to P s , and the lower limit is set to 0.1P s When the lining expands outward under the action of internal water pressure, the pressure borne by the lower layer of the flexible capsule begins to increase, and the fluid in the lower layer of the capsule will be discharged through the total valve to maintain the constant pressure between the lining and the surrounding rock;

[0026] When the internal water pressure decreases during maintenance or dry season, the lining begins to retract inward, and the pressure borne by the lower layer of the capsule begins to decrease. When the pressure is lower than 0.1P s , the fluid in the reserve capsule of the lower layer of the capsule will flow into the lower layer of the capsule through the left→right one-way hydraulic valve, causing the lower layer of the capsule to expand and the pressure between the lining and the surrounding rock to remain constant;

[0027] Seismic response balance: when the interface is dislocated by seismic shear waves, the non-Newtonian fluid in the flexible capsule thickens instantaneously, reducing the destructive effect of seismic shear waves on the interface between the lining and the surrounding rock.

[0028] Compared with the prior art, the present application has at least the following beneficial effects:

[0029] 1. Significantly improve the stability and deformation resistance of surrounding rock: the outer layer uses high-damping rubber-basalt fiber composite material, which is pre-pressed into the surrounding rock fissures to provide high tensile strength and energy absorption capacity for the surrounding rock. At the same time, the high ground stress compensation mechanism prevents the surrounding rock from entering the plastic stage, reducing the risk of deformation or collapse caused by stress release.

[0030] 2. Optimize internal water pressure management and prevent lining failure: the internal water pressure balance mechanism maintains constant pressure, avoiding lining voiding or cracking due to internal water pressure fluctuations. It is more reliable than traditional water blocking measures and is suitable for high internal water pressure scenarios.

[0031] 3. Enhance anti-seismic and anti-impact performance: seismic response balance thickens the non-Newtonian fluid, increases the tangential damping, and effectively dissipates the energy of seismic shear waves. At the same time, the composite shock-absorbing layer absorbs large deformation, reducing the risk of fault creep dislocation.

[0032] 4. Improved durability and environmental adaptability: The polyurethane and butyl rubber hybrid material can reduce performance degradation and extend the lining life in high temperature or corrosive environments, which is superior to conventional concrete lining. In addition, the composite shock-absorbing layer structure is suitable for various surrounding rock classes (such as medium-hard rock and soft rock), and reduces the dependence on surrounding rock grades through self-balancing. BRIEF DESCRIPTION OF DRAWINGS

[0033] The drawings described herein are intended to provide further understanding of the present application, and constitute a part of the present application. The illustrative embodiments of the present application and their description serve to explain the present application. They are not intended to be an improper limitation on the present application. In the drawings:

[0034] Fig. 1 FIG. 1 is a schematic diagram of a cross-sectional view of a surrounding rock-composite shock-absorbing layer-lining structure of the present application;

[0035] Fig. 2 FIG. 2 is a schematic diagram of a longitudinal section view of a surrounding rock-composite shock-absorbing layer-lining structure of the present application;

[0036] Fig. 3 FIG. 3 is a schematic diagram of a flexible bladder structure of the present application.

[0037] BRIEF DESCRIPTION OF DRAWINGS

[0038] 1: surrounding rock;

[0039] 2: composite shock-absorbing layer, 2-1: surrounding rock contact layer, 2-2: lining contact layer;

[0040] 3: lining,

[0041] 4: flexible bladder, 4-1: upper layer bladder, 4-2: lower layer bladder, 4-3: reserve bladder, 4-4: upper→lower one-way hydraulic valve, 4-5: left→right one-way hydraulic valve, 4-6: total valve. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments.

[0043] Embodiment 1: A pressure self-balancing tunnel lining surrounding rock composite shock-absorbing structure, as shown in FIG. 1. Fig. 1 、 Fig. 2As shown, it comprises a composite damping layer 2 between the surrounding rock 1 and the lining 3, which comprises a surrounding rock contact layer 2-1 on the outer side, i.e. close to the surrounding rock 1, and a lining contact layer 2-2 close to the inner layer, i.e. the lining 3, and the surrounding rock contact layer 2-1 and the lining contact layer 2-2 are constructed in layers and filled. Generally, the thickness of the surrounding rock contact layer 2-1 is 10-20 cm, and the thickness of the lining contact layer 2-2 is 15-25 cm. Among them, the surrounding rock contact layer 2-1 is a high-damping rubber-basalt fiber composite material, the composite material is pre-pressed into the surrounding rock 1 crack to absorb large deformation, and the basalt fiber in the composite material provides tensile strength, and the anti-movement ability is ≥50 mm. The lining contact layer 2-2 is a composite viscoelastic material uniformly embedded with flexible capsules 4, and the flexible capsules 4 are arranged at the same height as the lining contact layer 2-2; at the same time, along the cross section (circular ring direction) and the longitudinal section (tunnel axis direction) of the tunnel, the flexible capsules 4 are arranged at a distance of 1 / 2~1L, L is the side length of the flexible capsule 4. Specifically, the flexible capsule 4 is connected with the concrete lining 3 through chemical anchor bolts.

[0044] As shown in Fig. 3 The flexible capsule 4 is composed of an upper capsule 4-1 and a lower capsule 4-2 in a double-layer structure, and the upper and lower capsules 4-1 and 4-2 are connected by glue or stitching, and non-Newtonian fluid such as SiO2-polyethylene glycol suspension is filled in the upper and lower capsules 4-1 and 4-2. Specifically, the upper and lower capsules 4-1 and 4-2 are square with arc-shaped edges, and the side length is 40-50 cm. Because the upper and lower capsules 4-1 and 4-2 have different force adjustment effects, a reserve capsule 4-3 is arranged on one side of the lower capsule 4-2, the reserve capsule 4-3 occupies 1 / 3 of the area of the lower capsule 4-2, and the reserve capsule 4-3 is separated from the rest of the lower capsule 4-2, and a left→right one-way hydraulic valve 4-5 is arranged between them. An upper→lower one-way hydraulic valve 4-4 is arranged between the upper capsule 4-1 and the reserve capsule 4-3, and a total valve 4-6 is further arranged at the end of the lower capsule 4-2 away from the reserve capsule 4-3. A pressure sensor is arranged at each one-way hydraulic valve to adjust the pressure in the upper and lower capsules by sensing the surrounding rock pressure and lining pressure (internal water pressure) until the pressure balance is reached.

[0045] In this embodiment, the high-damping rubber-basalt fiber composite material is composed of the following raw materials by weight:

[0046] Rubber matrix: 50-70 parts; basalt fiber: 10-30 parts; compounding agent: 5-10 parts. Among them: the rubber matrix includes hydrogenated nitrile rubber (HNBR) and epoxidized eucommia rubber, and the mass ratio of the two is 1:1; the compounding agent includes vulcanizing agent (such as sulfur), reinforcing agent (such as carbon black), antioxidant, and accelerator, and the mass ratio of the vulcanizing agent, reinforcing agent, antioxidant, and accelerator is 1:1.

[0047] A method for preparing a high-damping rubber-basalt fiber composite material, comprising the following steps:

[0048] Step 1, Basalt fiber pretreatment: surface cleaning treatment is required, and the basalt fiber is soaked and washed with distilled water for 3-5 times. After washing, it is dried at 80°C for 3 hours for standby, so as to remove the sizing agent or impurities on the surface of the commercial fiber; and a silane coupling agent such as 3-aminopropyl triethoxysilane is treated. The silane coupling agent is slowly added to the basalt fiber and stirred for 6 hours. The mass ratio of the silane coupling agent to the basalt fiber is usually 3:100. After the reaction is completed, the unreacted silane coupling agent is washed with ethanol / deionized water, and finally dried at 80-120°C for 1-3 hours for curing.

[0049] Step 2, Rubber mixing: The rubber matrix is plasticized at 40-60°C, the pretreated basalt fiber and the compounding agent are added, and the internal mixer is mixed for 4 minutes, and the temperature is ≤60°C.

[0050] Step 3, vulcanization molding: The mixed rubber is placed in a mold and vulcanized at 170°C and a pressure of 10 MPa for 20 minutes.

[0051] In this embodiment, the composite viscoelastic material is a high-damping butyl rubber-polyurethane-silicon dioxide mixed material, wherein the butyl rubber (IIR) provides a high loss factor (tan δ≥0.3, frequency 1-10 Hz), the polyurethane (PU) enhances the anti-creep performance (reduction of compression set at 60°C by 15%), and the nano-silicon dioxide (SiO2) is added as a reinforcing agent to improve the compressive strength (≥5 MPa) and durability.

[0052] The high-damping butyl rubber-polyurethane-silicon dioxide mixed material is composed of the following raw materials by weight:

[0053] Matrix material: butyl rubber: 100 parts, providing basic damping performance; polyurethane elastomer: 30-50 parts, expanding the damping temperature range.

[0054] Functional filler: silicon dioxide: 20-40 parts, improving mechanical properties and damping loss.

[0055] Auxiliary components: vulcanizing agent: 2-5 parts, such as sulfur or peroxide, peroxide such as peroxide bis(tert-butyl isopropyl benzene) (BIPB), benzoyl peroxide (BPO).

[0056] Coupling agent: 1-3 parts, improving filler dispersion; such as silane coupling agent, silane coupling agent such as 3-aminopropyl triethoxysilane. Antioxidant: 2-5 parts, improving weather resistance.

[0057] A method for preparing a high-damping butyl rubber-polyurethane-silicon dioxide mixed material, using a blending process, comprising the following steps:

[0058] Step 1, mixing stage: plasticize butyl rubber and polyurethane elastomer in the mixer, temperature is 80-100℃, add antioxidant and mix well.

[0059] Step 2, filler dispersion: add silica and coupling agent in batches to ensure uniform dispersion, speed is 40-60rpm.

[0060] Step 3, vulcanization molding: transfer to the open mill and add vulcanizing agent, thin pass out sheet and then mold and vulcanize, temperature is 150-160℃, pressure is 10-15MPa, time is 20-30 minutes.

[0061] In this embodiment, the material of the flexible capsule 4 is polyurethane-Kevlar composite material, and the upper pressure limit of a single flexible capsule 4 is 60MPa. The polyurethane-Kevlar composite material can refer to Advanced Textile Based Polymer Composites: Synthesis, Characterization and Applications, which studies the application of polyurethane / Kevlar fabric composite material in bulletproof material, proves that it has excellent impact resistance, and has passed the NIJ 0101.06 bulletproof standard test, confirming that the polyurethane / Kevlar composite material can be made into a light weight, high strength, impact resistant flexible protective structure.

[0062] Example 2: A pressure self-balancing method using the composite damping structure described in Example 1, referring to Figs. 1 to 3 , including:

[0063] High ground stress compensation: after the excavation of the chamber, the stress of the surrounding rock is released, the surrounding rock 1 deforms and starts to extrude the composite damping layer 2 between the lining 3 and the surrounding rock 1, the upper capsule 4-1 of the flexible capsule 4 starts to bear pressure, assuming that the design value of the surrounding rock pressure is P0, the upper limit value of the pressure borne by the upper capsule 4-1 is set to P s (Generally, for medium-hard rock P s is about 0.4P0, and for soft rock P s is about 0.8P0), as long as the external pressure (confining pressure) is greater than P s , the fluid in the upper capsule 4-1 flows into the reserve capsule 4-3 of the lower capsule 4-2 through the upper→lower one-way hydraulic valve 4-4. Because the surrounding rock 1 is still in the elastic stable deformation stage when the surrounding rock pressure is unloaded from P0 to P s , the upper capsule 4-1 provides P s pressure to form a balanced system with the surrounding rock pressure, which can prevent the surrounding rock stress from being further released and prevent the surrounding rock from deforming into the plastic stage, so that the surrounding rock 1 is in a stable state.

[0064] Inner water pressure balance: when the upper layer of the capsule 4-1 reaches the balance with the surrounding rock pressure, according to the principle of force transmission, the pressure between the lower layer of the flexible capsule 4-2 and the lining 3 is also P s , the upper limit of the pressure borne by the lower layer of the capsule 4-2 is set to P s , and the lower limit is set to 0.1P s . This means that when the lining 3 expands outward under the action of the inner water pressure, the pressure borne by the lower layer of the flexible capsule 4-2 begins to increase, and then the fluid in the lower layer of the capsule 4-2 is discharged through the total valve 4-6, so that the pressure between the lining and the surrounding rock can be kept constant. In special cases, such as maintenance or dry season, when the inner water pressure decreases, the lining 3 begins to shrink inward, and the pressure borne by the lower layer of the capsule 4-2 begins to decrease, and when the pressure is lower than 0.1P s , it indicates that the lining 1 and the composite shock-absorbing layer 2 may be empty, at this time the fluid in the reserve capsule 4-3 of the lower layer of the capsule 4-2 will flow into the lower layer of the capsule 4-2 through the left→right one-way hydraulic valve 4-5, so that the lower layer of the capsule 4-2 expands and the pressure between the lining and the surrounding rock remains constant.

[0065] Seismic response balance: when the interface (such as the contact surface of the lining and the composite shock-absorbing layer, and the contact surface of the composite shock-absorbing layer and the surrounding rock) is dislocated due to the seismic shear wave, the non-Newtonian fluid (such as SiO2-polyethylene glycol suspension) in the flexible capsule 4 thickens instantaneously, greatly improves the tangential damping of the composite shock-absorbing layer, and increases the energy consumption of the seismic shear wave, thereby reducing the damage of the seismic shear wave to the interface between the lining and the surrounding rock.

[0066] The materials listed in the present application, as well as the upper and lower limits, interval values, and process parameters (such as temperature, time, etc.) of the materials in the present application can all achieve the present application, and examples are not listed one by one; at the same time, the materials involved in the examples are all common commercially available goods.

[0067] The above is only a specific implementation in the present application, and the protection scope of the present application is not limited to this. Any person skilled in the art can understand and think of changes or substitutions within the technical scope disclosed by the present application, which should be covered by the scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A pressure-self-balancing composite damping structure for tunnel lining surrounding rock, comprising a composite damping layer disposed between the surrounding rock and the lining, characterized in that, The composite damping layer includes a rock contact layer near the surrounding rock and a lining contact layer near the lining; the rock contact layer is a high-damping rubber-basalt fiber composite material, pre-compressed and embedded in the surrounding rock fissures; the lining contact layer is a composite viscoelastic material uniformly embedded with flexible bladders. The flexible capsule consists of an upper capsule and a lower capsule, forming a double-layer structure. The upper and lower capsules are filled with non-Newtonian fluid. A reserve capsule is provided on one side of the lower capsule, and the reserve capsule is separated from the rest of the lower capsule. One-way hydraulic valves are provided between the upper and lower capsules and between the reserve capsule and the lower capsule. A main valve is also provided at the end of the lower capsule away from the reserve capsule.

2. The pressure-self-balancing tunnel lining surrounding rock composite vibration reduction structure according to claim 1, characterized in that, The flexible capsule is made of polyurethane-Kevlar composite material, and the upper limit of pressure bearing of a single flexible capsule is 60MPa; the flexible capsule is set at the same height as the lining contact layer; the non-Newtonian fluid is SiO2-polyethylene glycol suspension.

3. The pressure-self-balancing tunnel lining surrounding rock composite vibration reduction structure according to claim 1, characterized in that, A pressure sensor is provided at each of the one-way hydraulic valves to regulate the pressure in the upper and lower layers of the bladder by sensing the surrounding rock pressure and the lining pressure until pressure balance is achieved.

4. The pressure-self-balancing tunnel lining surrounding rock composite vibration reduction structure according to claim 1, characterized in that, Along both the cross-section and longitudinal section of the tunnel, the flexible bladders are arranged at intervals of 1 / 2 to 1L, where L is the side length of the flexible bladder; the upper and lower bladders are square with arc-shaped edges and a side length of 40 to 50 cm; the reserve bladder occupies 1 / 3 of the area of ​​the lower bladder.

5. The pressure-self-balancing tunnel lining surrounding rock composite vibration reduction structure according to claim 1, characterized in that, The flexible capsule is connected to the lining by chemical anchors.

6. The pressure-self-balancing tunnel lining surrounding rock composite vibration reduction structure according to claim 1, characterized in that, The high-damping rubber-basalt fiber composite material is composed of the following raw materials in parts by weight: rubber matrix: 50–70 parts; basalt fiber: 10–30 parts; compounding agent: 5–10 parts; wherein: The rubber matrix consists of hydrogenated nitrile butadiene rubber and epoxidized eucommia rubber, with a mass ratio of 1:

1. The compounding agents include vulcanizing agents, reinforcing agents, antioxidants, and accelerators, with a mass ratio of 1:

1.

7. The pressure-self-balancing tunnel lining surrounding rock composite vibration reduction structure according to claim 6, characterized in that, The preparation method of the high-damping rubber-basalt fiber composite material includes the following steps: Step 1: Basalt fiber pretreatment: Soak and wash with distilled water 3-5 times, and dry at 80℃ for 3 hours after washing; Slowly add silane coupling agent to the washed basalt fiber and stir for 6 hours. The mass ratio of silane coupling agent to basalt fiber is 3:

100. After the reaction is completed, wash off the unreacted silane coupling agent with ethanol / deionized water, and finally dry at 80~120℃ for 1-3 hours to cure. Step 2, Rubber mixing: The rubber matrix is ​​plasticized at 40–60℃, and the pretreated basalt fiber and compounding agents are added. The mixture is then mixed in an internal mixer for 4 minutes at a temperature ≤60℃. Step 3, vulcanization molding: Place the compounded rubber into the mold and vulcanize for 20 minutes at 170℃ and 10MPa pressure.

8. The pressure-self-balancing tunnel lining surrounding rock composite vibration reduction structure according to claim 1, characterized in that, The high-damping butyl rubber-polyurethane-silica blend material is composed of the following raw materials in parts by weight: butyl rubber: 100 parts; polyurethane elastomer: 30-50 parts; silica: 20-40 parts; vulcanizing agent: 2-5 parts; coupling agent: 1-3 parts; antioxidant: 2-5 parts.

9. The pressure-self-balancing tunnel lining surrounding rock composite vibration reduction structure according to claim 8, characterized in that, The preparation method of the high-damping butyl rubber-polyurethane-silica hybrid material adopts a blending process and includes the following steps: Step 1, Internal mixing stage: Plasticize butyl rubber and polyurethane elastomer in an internal mixer at a temperature of 80-100℃, add antioxidant and mix well; Step 2, Filler dispersion: Add silica and coupling agent in batches to ensure uniform dispersion, with a rotation speed of 40-60 rpm; Step 3, vulcanization molding: Transfer to an open mill, add vulcanizing agent, and after thinning, mold vulcanize at a temperature of 150-160℃, a pressure of 10-15MPa, and a time of 20-30 minutes.

10. A pressure self-balancing method, employing the pressure self-balancing tunnel lining surrounding rock composite vibration reduction structure as described in any one of claims 1-9, characterized in that, include: High ground stress compensation: After the excavation of the tunnel, the stress in the surrounding rock is released, and the surrounding rock undergoes certain deformation, beginning to compress the composite damping layer between the lining and the surrounding rock. The upper layer of the flexible bladder begins to bear pressure. Assuming the design value of the surrounding rock pressure is P0, the upper limit of the pressure that the upper bladder can withstand is set to P. s As long as the external pressure is greater than P s The fluid in the upper bladder flows into the storage bladder of the lower bladder through the upper → lower one-way hydraulic valve, because the confining pressure is unloaded from P0 to P. s At this time, the surrounding rock is still in the elastically stable deformation stage, and P is provided by the upper capsule. s The pressure and the surrounding rock pressure form a balanced system; Internal water pressure balance: When the pressure between the upper chamber and the surrounding rock reaches equilibrium, according to the principle of force transmission, the pressure between the lower chamber of the flexible chamber and the lining is also P. s The upper limit of the pressure that the lower cyst can withstand is set to P. s The lower limit is set to 0.1P. s When the lining expands outward under the action of internal water pressure, and the pressure of the lower layer of the flexible bladder begins to increase, the fluid in the lower layer of the bladder will be discharged through the main valve to maintain a constant pressure between the lining and the surrounding rock. During maintenance or the dry season, when the internal water pressure decreases, the lining begins to recede inward, and the pressure on the lower chamber begins to decrease. When the pressure drops below 0.1P... s At this time, the fluid in the reserve bladder of the lower bladder will flow into the lower bladder through the left-to-right one-way hydraulic valve, causing the lower bladder to expand and the pressure between it and the lining to remain constant. Seismic response equilibrium: When seismic shear waves cause interface displacement, the non-Newtonian fluid inside the flexible bladder thickens instantaneously, reducing the destructive effect of seismic shear waves on the interface between the lining and the surrounding rock.

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