Anti-erosion tunnel structure

Abstract

The invention discloses an anti-erosion tunnel structure. The anti-erosion tunnel structure comprises a flexible concrete layer, an energy dissipation layer and a rigid concrete layer which are sequentially arranged from outside to inside. The energy dissipation layer comprises a drainage plate layer, a foam buffer layer and a waterproof plate layer, and the drainage plate layer is connected with the flexible concrete layer; the foam buffer layer is arranged on the inner side of the drainage plate layer; the waterproof plate layer is arranged on the inner side of the foam buffer layer and connected with the rigid concrete layer. According to the anti-erosion tunnel structure, the flexible concrete layer has certain deformability, the anti-cracking performance is effectively improved, the rigidity of the rigid concrete layer structure is large, and the bearing requirement is met; the foam buffer layer is positioned between the flexible concrete layer and the rigid concrete layer to consume the deformation of the flexible concrete layer; in addition, the drainage plate layer can effectively drain liquid permeating from the flexible concrete layer, the waterproof plate layer ensures that the liquid does not permeate into the rigid concrete layer, and the solution erosion resistance of the tunnel can be effectively improved through the combination of drainage and water prevention.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of tunnel structure, and particularly relates to an anti-erosion tunnel structure. BACKGROUND

[0002] In tunnel engineering, the tunnel structure in the environment containing sulfate salt is subject to serious erosion problem of sulfate salt complex solution. The sulfate salt can erode the tunnel surrounding rock and the supporting structure, resulting in the decrease of the stiffness and the durability of the tunnel structure, and further causing a series of problems such as structure deterioration, cracking and leakage, which seriously affect the normal use and safety of the tunnel.

[0003] At present, the traditional tunnel support mostly adopts single rigid support or single flexible support, and the rigid support structure is easy to be brittle and cracked, and the flexible support structure has insufficient stiffness. SUMMARY

[0004] The main purpose of the present application is to provide an anti-erosion tunnel structure, which aims to solve the problem that the traditional tunnel support mostly adopts single rigid support or single flexible support.

[0005] To achieve the above-mentioned purpose, the present application provides an anti-erosion tunnel structure, which comprises a flexible concrete layer, an energy dissipation layer and a rigid concrete layer arranged in sequence from outside to inside; the energy dissipation layer comprises a drainage board layer, a foam buffer layer and a waterproof board layer, the drainage board layer is connected with the flexible concrete layer, and the drainage board layer is used for draining the water penetrating into the energy dissipation layer; the foam buffer layer is arranged on the inner side of the drainage board layer, and the foam buffer layer is used for absorbing the deformation amount generated by the water absorption of the flexible concrete layer; the waterproof board layer is arranged on the inner side of the foam buffer layer and is connected with the rigid concrete layer, and the waterproof board layer is used for blocking the water from the energy dissipation layer into the rigid concrete layer.

[0006] Optionally, the drainage direction of the drainage board layer is the same as the circumferential direction of the tunnel, and a drainage ditch is further arranged in the tunnel; the anti-erosion tunnel structure further comprises at least two drainage main pipes and a plurality of drainage branch pipes, the axial directions of the at least two drainage main pipes are the same as the extension direction of the tunnel, at least one drainage main pipe is arranged on each side of the tunnel, and the drainage main pipe is in communication with the drainage board layer; the plurality of drainage branch pipes are arranged at intervals on the outer periphery of the drainage main pipe in the extension direction of the drainage main pipe, and the drainage branch pipe is in communication with the drainage main pipe and the drainage ditch.

[0007] Optionally, the anti-erosion tunnel structure further comprises a plurality of anchor rods, and the plurality of anchor rods are arranged around the outer periphery of the energy dissipation layer and penetrate through the flexible concrete layer.

[0008] Optionally, the flexible concrete layer, the energy dissipation layer and the rigid concrete layer integrally form a structure layer, in a cross section perpendicular to the tunnel extending direction, the structure layer is arc-shaped or ring-shaped, in the gravity direction, the inner periphery of the tunnel is divided into a lower bottom region and an upper arch region; when the structure layer is arc-shaped, the structure layer is arranged at the arch region; when the structure layer is ring-shaped, the structure layer is arranged around the inner periphery of the tunnel.

[0009] Optionally, the flexible concrete layer is mixed with fibers.

[0010] Optionally, the fibers are polypropylene fibers and / or steel fibers.

[0011] Optionally, the rigid concrete layer is provided with profile steels arranged along the tunnel periphery; the profile steels are multiple and arranged at intervals in the extending direction of the tunnel.

[0012] Optionally, the profile steels arranged along the tunnel periphery are divided into multiple sections, and each section is connected by bolts.

[0013] Optionally, the profile steels are coated with an epoxy resin coating; wherein the dry film thickness of the epoxy resin coating is ≥ 300 μm.

[0014] Optionally, the rigid concrete layer is mixed with slag powder or silica fume.

[0015] The anti-erosion tunnel structure provided by the embodiments of the present application breaks through the limitation of traditional single rigid support or single flexible support in use, the flexible concrete layer has certain deformation capacity, effectively improves the anti-cracking performance, and improves the anti-seepage effect, the rigid concrete layer has large structural rigidity and meets the bearing requirement; the foam buffer layer is located between the flexible concrete layer and the rigid concrete layer to consume the deformation amount of the flexible concrete layer, thereby preventing the deformation and fragmentation of the rigid concrete layer; in addition, the drainage plate layer can effectively drain the liquid seeping from the flexible concrete layer, the waterproof plate layer ensures that the liquid cannot seep into the rigid concrete layer, and the combination of drainage and waterproof can effectively improve the anti-erosion capacity of the tunnel to the solution. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the prior art and the present application, the drawings needed in the description of the prior art and the embodiments of the present application will be briefly introduced below. Obviously, the drawings in the following description are only exemplary, and other drawings can be derived from the provided drawings without creative labor for those skilled in the art.

[0017] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed herein.

[0018] Figure 1 This is a schematic diagram of the overall structure of an anti-erosion tunnel structure proposed in an embodiment of this application. Figure 1 ; Figure 2 This is a schematic diagram of the overall structure of an anti-erosion tunnel structure proposed in an embodiment of this application. Figure 2 ; Figure 3 This is a schematic diagram of the drainage main pipe structure according to an embodiment of this application.

[0019] In the diagram: 1. Flexible concrete layer; 2. Energy dissipation layer; 3. Rigid concrete layer; 4. Drainage ditch; 5. Main drainage pipe; 6. Branch drainage pipe; 7. Anchor bolt.

[0020] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0023] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0025] The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] Figure 1 This is a schematic diagram of the overall structure of an anti-erosion tunnel structure proposed in an embodiment of this application. Figure 1 ; Figure 2 This is a schematic diagram of the overall structure of an anti-erosion tunnel structure proposed in an embodiment of this application. Figure 2 ; Figure 3 This is a schematic diagram of the drainage main pipe structure according to an embodiment of this application.

[0027] refer to Figure 1 and Figure 2 This application provides an anti-erosion tunnel structure, which may include a flexible concrete layer 1, an energy dissipation layer 2, and a rigid concrete layer 3 arranged sequentially from the outside to the inside. The energy dissipation layer 2 may include a drainage board layer, a foam buffer layer, and a waterproof board layer. The drainage board layer is connected to the flexible concrete layer 1 and is used to drain water that seeps into the energy dissipation layer 2. The foam buffer layer is disposed inside the drainage board layer and is used to absorb the deformation caused by water absorption by the flexible concrete layer 1. The waterproof board layer is disposed inside the foam buffer layer and is connected to the rigid concrete layer 3. The waterproof board layer is used to prevent water from entering the rigid concrete layer 3 from the energy dissipation layer 2.

[0028] The anti-erosion tunnel structure proposed in this application overcomes the limitations of traditional single rigid or single flexible support during use. The flexible concrete layer 1 has a certain deformation capacity, effectively improving crack resistance and seepage prevention. The rigid concrete layer 3 has high structural rigidity, meeting the load-bearing requirements. A foam buffer layer is located between the flexible concrete layer 1 and the rigid concrete layer 3 to absorb the deformation of the flexible concrete layer 1, thereby preventing the rigid concrete layer 3 from deforming and cracking. In addition, the drainage board layer can effectively drain the liquid that seeps in from the flexible concrete layer 1, and the waterproof board layer ensures that the liquid does not seep into the rigid concrete layer 3. The combination of drainage and waterproofing can effectively improve the tunnel's resistance to solution erosion.

[0029] It should be noted that this application uses a flexible concrete layer 1, a foam buffer layer in the energy dissipation layer 2, and a rigid concrete layer 3 to form a ternary synergistic system with an outer flexible layer, a middle transition layer, and an inner rigid layer. Through the stress redistribution mechanism of the rigid-flexible interface, the structure can still maintain more than 60% of its load-bearing capacity when the material deteriorates due to sulfate corrosion. At the same time, it solves the limitations of traditional solutions, such as the easy cracking of the rigid support structure and the insufficient stiffness of the single flexible support structure.

[0030] In addition, in the energy dissipation layer 2, the outer layer is a drainage board layer, which can effectively drain the liquid that seeps in from the flexible concrete layer 1, the middle layer is a foam buffer layer, and the inner layer is a waterproof board layer, which effectively isolates the liquid and prevents the liquid that seeps through the drainage board and the foam buffer layer from reaching the rigid concrete layer 3. In this way, a drainage and waterproof protection system is formed, which improves the erosion resistance efficiency by more than 30% compared with the traditional single drainage or single waterproof design. The liquid mentioned above is sulfate solution or groundwater, etc.

[0031] It should be noted that the drainage board layer, the foam buffer layer, and the waterproof board layer are independent structures and can be fixed by compression between the flexible concrete layer 1 and the rigid concrete layer 3.

[0032] refer to Figure 1 and Figure 3 In an exemplary embodiment, the drainage direction of the drainage board layer is the same as the circumferential direction of the tunnel, and a drainage ditch 4 is also provided inside the tunnel; the erosion-resistant tunnel structure may also include at least two main drainage pipes 5 and multiple branch drainage pipes 6, the axial direction of the at least two main drainage pipes 5 is the same as the extension direction of the tunnel, at least one main drainage pipe 5 is provided on each side of the tunnel, and the main drainage pipes 5 are connected to the drainage board layer; the multiple branch drainage pipes 6 are spaced apart on the outer periphery of the main drainage pipes 5 in the extension direction of the main drainage pipes 5, and the branch drainage pipes 6 connect the main drainage pipes 5 and the drainage ditch 4.

[0033] It should be understood that multiple drainage grooves can be provided on the drainage board layer. The extension direction of the drainage grooves is the same as that of the tunnel. Multiple drainage grooves are arranged in sequence in the extension direction of the tunnel, so that drainage channels can be formed on the drainage board layer. The direction of liquid flow in the drainage channels is the drainage direction of the drainage board layer.

[0034] Among them, such as Figure 1 and Figure 3 As shown, Figure 1 The middle energy dissipation layer 2 is connected to a drainage main 5 at both ends in the circumferential direction of the tunnel. That is, the drainage channel in the energy dissipation layer 2 is connected to the drainage main 5. In this way, the liquid on the drainage plate layer can flow into the drainage main 5 and then into the drainage ditch 4 in the tunnel through the drainage branch pipe 6 on the drainage main 5, thereby discharging the liquid.

[0035] It should be understood that since the extension direction of the main drainage pipe 5 is the same as the extension direction of the drainage ditch 4 and the tunnel, multiple drainage branch pipes 6 can be installed. These multiple drainage branch pipes 6 are distributed at intervals along the extension direction of the tunnel to connect the main drainage pipe 5 and the drainage ditch 4. The denser the arrangement of the multiple drainage branch pipes 6 along the extension direction of the tunnel, the better the drainage effect.

[0036] refer to Figure 1 In an exemplary embodiment, the erosion-resistant tunnel structure may further include multiple anchor bolts 7, which are arranged around the outer periphery of the energy dissipation layer 2 and penetrate the flexible concrete layer 1.

[0037] Specifically, by setting multiple anchor bolts 7 around the tunnel, the overall stability of the surrounding rock can be effectively enhanced. In addition, the anchor bolts 7 distributed around the tunnel can form a reinforced arch, improving the load-bearing capacity of the entire support structure.

[0038] It should be understood that the anchor bolts 7 distributed around the tunnel in the circumference direction are referred to as a group of rods. There are multiple groups of rods, and the multiple groups of rods are distributed at intervals in the extension direction of the tunnel.

[0039] refer to Figure 1 and Figure 2 In an exemplary embodiment, the flexible concrete layer 1, the energy dissipation layer 2, and the rigid concrete layer 3 together constitute a structural layer. On a cross section perpendicular to the tunnel extension direction, the structural layer is arc-shaped or annular. In the direction of gravity, the inner periphery of the tunnel is divided into a bottom region located below and an arched region located above. When the structural layer is arc-shaped, the structural layer is disposed in the arched region. When the structural layer is annular, the structural layer is disposed around the inner periphery of the tunnel.

[0040] like Figure 1As shown, when the sulfate concentration in the tunnel is not high and the permeability of the surrounding rock is weak, the structural layer is arc-shaped and only set in the arched area of ​​the tunnel, which can effectively protect against sulfate erosion. This type of structural layer support is called semi-enclosed.

[0041] like Figure 2 As shown, when the sulfate concentration in the tunnel is high and the surrounding rock of the tunnel is highly permeable, the structural layer is ring-shaped, that is, the structural layer is set around the circumference of the tunnel, which can effectively protect against sulfate erosion. This type of structural layer support is called full wrap.

[0042] It should be understood that when using the full-enclosure method, the bottom area concrete structure can be lined first, and then the arch area concrete structure can be constructed by secondary lining. In particular, at the connection area between the energy dissipation layer 2 in the arch area concrete structure and the energy dissipation layer 2 in the bottom area concrete structure, a grouting water-stop ring can be added to ensure sealing and prevent liquid seepage, thereby achieving full-enclosure waterproofing and emergency drainage.

[0043] In an exemplary embodiment, the flexible concrete layer 1 is mixed with fibers; the fibers are polypropylene fibers and / or steel fibers.

[0044] Specifically, the addition of fibers to the flexible concrete layer 1 can effectively improve the ductility of the concrete, ensuring that the flexible concrete layer 1 has a certain degree of ductility and meets the requirements for crack resistance.

[0045] The fibers can be polypropylene fibers and / or steel fibers; polypropylene fibers can significantly improve the impermeability of concrete and prevent water penetration; steel fibers can significantly improve the compressive, flexural and tensile fatigue resistance of concrete, and further improve the service life of the flexible concrete layer 1.

[0046] In an exemplary embodiment, the rigid concrete layer 3 is provided with steel sections arranged along the circumference of the tunnel; there are multiple steel sections and they are spaced apart in the extension direction of the tunnel.

[0047] Specifically, the steel section can be an I-beam, which is arranged around the inside of the tunnel to improve the structural strength of the rigid concrete layer 3.

[0048] It should be understood that the steel sections installed along the circumference of the tunnel are divided into multiple sections, which are connected by bolts. This facilitates the transportation of each section and allows for assembly inside the tunnel, making construction more convenient.

[0049] It should be noted that multiple steel sections are spaced apart along the tunnel's extension direction. The smaller the spacing between the steel sections, the higher the structural strength of the rigid concrete layer 3.

[0050] In an exemplary embodiment, the steel profile is coated with an epoxy resin coating; wherein the dry film thickness of the epoxy resin coating is ≥300μm.

[0051] Specifically, epoxy resin coating can effectively isolate the steel profile from contact with the external environment, prevent liquids, oxygen and other substances from corroding the steel profile, and effectively improve the service life of the steel profile.

[0052] Among them, the dry film thickness of the epoxy resin coating is ≥300μm, which can further improve the corrosion resistance of the epoxy resin coating, thus extending the service life of the rigid concrete layer 3 by more than 50 years compared with traditional concrete.

[0053] In an exemplary embodiment, slag powder or silica fume is mixed into the rigid concrete layer 3, which can effectively improve the durability of the rigid concrete.

[0054] Furthermore, sulfate attack is a key factor in the deterioration of concrete structures, and its concentration directly affects the type and extent of attack. The permeability coefficient of the surrounding rock reflects the groundwater seepage capacity and is directly related to the risk of water inrush in tunnels and the stability of the support structure. The stress-intensity ratio of the surrounding rock reflects the stability of the surrounding rock. When using the above structures, different parameter schemes can be formulated based on the sulfate concentration, permeability coefficient of the surrounding rock, and stress-intensity of the surrounding rock.

[0055] For example, sulfate concentrations are divided into three levels, as follows: Level 1: Sulfate concentration <1000mg / L, environmental water mainly erodes by physical means, with weak chemical corrosion, and concrete structures only experience slight carbonation or surface weathering.

[0056] Level 2: Sulfate concentration ≤ 8000 mg / L, coexistence of ettringite and gypsum-type expansion failure, gypsum-type failure is dominant when pH < 11.5, the internal porosity of concrete increases and the strength gradually decreases.

[0057] Level 3: Sulfate concentration > 8000 mg / L, mainly gypsum-type expansion failure, decomposition of hydrated calcium silicate gel leading to loss of cementitious properties, severe spalling and cracking of concrete, and a significant decrease in structural load-bearing capacity.

[0058] The sulfate concentration was determined by ion chromatography with an accuracy of ±10 mg / L.

[0059] The permeability coefficient of the surrounding rock is divided into three levels, as follows: Level 1: Permeability coefficient < 1 × 10 -7 The flow rate is m / s, the permeability of the surrounding rock is extremely low, and groundwater is unlikely to seep into the tunnel.

[0060] Level 2: 1×10 -7 m / s≤permeability coefficient≤1×10 -5 The groundwater flow rate is m / s, which is moderate and may cause local leakage or increased water pressure.

[0061] Level 3: Permeability coefficient > 1×10 -5 The groundwater has a flow rate of m / s and high permeability, making it prone to disasters such as sudden water and mud flow, and quicksand.

[0062] The permeability coefficient is calculated according to Darcy's law.

[0063] It should be noted that the surrounding rock stress-intensity ratio is usually defined as the ratio of the maximum principal stress acting on the medium to the uniaxial compressive strength of the medium, and the expression is: Stress intensity ratio = σ1 / σ

[0064] Wherein, σ1 refers to the maximum principal stress borne by the rock mass or rock, with the unit being MPa, which can be obtained through field measurement (such as stress relief method, hydraulic fracturing method) or numerical simulation calculation; σ Uniaxial compressive strength refers to the uniaxial compressive strength of rock, measured in MPa. It can be determined through indoor testing (by axially compressing a standard rock sample until it fails without lateral restraint) and reflects the rock's compressive strength.

[0065] The stress intensity of the surrounding rock is divided into three levels, as follows: Level 1: Stress intensity ratio < 0.3. At this point, the surrounding rock is in the elastic deformation stage. After excavation, the overall stability is good, the internal stress does not exceed the elastic limit of the rock, and geological disasters such as rock bursts and collapses are not likely to occur.

[0066] Level 2: 0.3 ≤ stress-intensity ratio ≤ 0.7, the surrounding rock has entered the plastic deformation stage, the stress in some areas exceeds the rock yield strength, and there may be spalling, small-scale rockfall or slight collapse.

[0067] Level 3: Stress intensity ratio > 0.7, the surrounding rock is in a state of high stress, the internal stress is close to or exceeds the uniaxial compressive strength of the rock, and it is prone to violent rock bursts, large-scale deformation (such as large deformation of soft rock) or overall instability.

[0068] In the above formula, the maximum principal stress borne by the rock mass or rock can be obtained through field measurement (such as stress relief method, hydraulic fracturing method) or numerical simulation calculation; the uniaxial compressive strength of the rock can be determined by indoor test (by axially compressing a standard rock sample to failure under no lateral constraint conditions), reflecting the rock's own compressive strength.

[0069] Specifically, based on the above parameter levels, the disaster risk level of tunnels can be divided into low risk, medium risk, and high risk.

[0070] The risk level is defined as follows: each parameter corresponds to a level 1, 2, or 3. When all parameters correspond to a level 1, the risk level is low. When one parameter corresponds to a level 2 and the other parameters correspond to a level 1, the risk level is medium. When one parameter corresponds to a level 3 or two or more parameters correspond to a level 2, the risk level is high.

[0071] Based on the disaster risk level of the tunnel, the specific parameter scheme is as follows: Low-risk parameter scheme: 1 / 10≤span-to-rise ratio of invert arch ≤ 1 / 8 (e.g., 1 / 9) is suitable for working conditions with sulfate concentration < 1000 mg / L and good surrounding rock integrity, ensuring the deformation resistance of the invert arch under conventional loads.

[0072] Flexible concrete layer 1: C30 high ductility fiber concrete is used, with a thickness of 20cm≤25cm and a fiber content of 0.8%≤1.0% (such as polypropylene fiber), to meet the crack resistance requirements in a slightly corrosive environment.

[0073] Energy dissipation layer 2: Outer layer 3cm thick drainage board layer + middle layer 2cm thick polyethylene foam board buffer layer + inner layer 1.5mm thick high-density polyethylene waterproof board layer. Along the tunnel's extension direction, adjacent drainage branch pipes are spaced 5m apart, with a permeability coefficient ≤1×10⁶. - ³cm / s, achieving limited drainage while isolating sulfate solution.

[0074] Rigid concrete layer 3: The secondary lining uses C35 concrete with a thickness of 45cm to 50cm and is reinforced with I16 I-beams. In the direction of tunnel extension, the spacing between adjacent steel sections is 1.2m and the steel content of the steel section is 1.5% to 2.0%, which meets the basic load-bearing requirements.

[0075] Medium-risk parameter scheme: 1 / 8≤invert arch rise-to-span ratio≤1 / 6 (e.g., 1 / 7) is suitable for working conditions where sulfate concentration is 1000mg / L≤8000mg / L and joints are present in the surrounding rock, thereby enhancing the invert arch's resistance to seepage pressure.

[0076] Flexible concrete layer 1: C30 high ductility concrete is used, with a thickness of 25cm≤30cm and a fiber content of 1.0%≤1.2% (such as a mixture of steel fiber and polypropylene fiber) to improve erosion resistance and ductility.

[0077] Energy dissipation layer 2: Outer layer 5cm thick drainage board layer + middle layer 5cm thick polyurethane foam board buffer layer + inner layer 1.5mm thick high-density polyethylene waterproof board layer. Along the tunnel's extension direction, adjacent drainage branch pipes are spaced 3m apart, with a permeability coefficient ≤1×10⁶. -4 cm / s, achieving "primarily water-resistant and secondarily drainage".

[0078] Rigid concrete layer 3: The secondary lining uses C40 concrete with a thickness of 50cm≤55cm and is reinforced with I20a I-beams. In the direction of tunnel extension, the spacing between adjacent steel sections is 1.0m, the steel content of the steel section is 2.0%≤2.5%, and 5%~8% (including boundary values ​​such as 5% and 8%) of silica fume is added to improve impermeability.

[0079] High-risk parameter scheme: A ratio of 1 / 6 to 1 / 5 (e.g., 1 / 5.5) is suitable for working conditions with sulfate concentration > 8000 mg / L, fractured surrounding rock, and high water pressure. The large ratio of 1 / 6 to 1 / 5 improves the structural stiffness.

[0080] Flexible concrete layer 1: C35 high ductility concrete is used, with a thickness of 30cm≤35cm and a fiber content of 1.2%≤1.5% (mainly steel fiber). Combined with shotcrete technology, the crack resistance and erosion resistance of flexible concrete layer 1 are ensured.

[0081] Energy dissipation layer 2: Outer layer 5cm thick drainage board layer + middle layer 10cm thick foamed concrete buffer layer + inner layer 1.5mm thick high-density polyethylene waterproof board layer. Along the tunnel's extension direction, adjacent drainage branch pipes are spaced 2m apart, with a permeability coefficient ≤1×10⁶. -5 cm / s, achieving full-enclosed water isolation and emergency drainage.

[0082] Rigid concrete layer 3: The secondary lining uses C45 high-performance concrete with a thickness of 55cm≤60cm. It is reinforced with I22b I-beams. In the direction of tunnel extension, the spacing between adjacent steel sections is 0.8m, and the steel content of the steel section is 2.5%≤3.0%. It is coated with epoxy resin. 10%~15% (including the boundary value of 10% and 15%) of slag powder and sulfate-resistant admixtures are added to the concrete to improve the durability of rigid concrete layer 3.

[0083] In low-risk and medium-risk scenarios, a semi-enclosed solution is adopted for the structural layer, such as... Figure 1 As shown, in high-risk situations, the structural layer adopts a fully enclosed solution, such as... Figure 2 As shown.

[0084] Furthermore, the stiffness and durability indicators of the tunnel structure under different risk scenarios were calculated. The stiffness indicator can be determined by calculating parameters such as the deformation and stress distribution of the tunnel structure, while the durability indicator can be determined by calculating parameters such as the sulfate resistance of concrete and the corrosion rate of reinforcing steel.

[0085] Specifically, stiffness response indicators can be calculated by establishing a tunnel structure model using finite element software (such as ANSYS) to calculate the crown settlement, sidewall displacement, and structural stress concentration factor under different schemes. For example, high-risk schemes may require crown settlement ≤ 0.3 mm, sidewall displacement ≤ 0.5 mm, and stress concentration factor ≤ 1.8. The specific requirements for stiffness response indicators for each scheme can be formulated according to the actual situation.

[0086] Durability indicators can be calculated using the Nernst equation combined with accelerated corrosion tests to determine the sulfate resistance life of concrete, the critical time for steel corrosion, and the crack propagation rate of the structure. Specifically, the requirements can be a sulfate resistance life of concrete ≥100 years, a critical time for steel corrosion ≥80 years, and a crack propagation rate of ≤0.02 mm / year; here, concrete includes flexible concrete layer 1 and rigid concrete layer 3.

[0087] Taking the high-risk scheme as an example, if the tunnel structure stiffness reflection index or the tunnel structure durability reflection index does not meet the requirements, the parameters can be adjusted within the parameter range of the high-risk scheme until the tunnel structure stiffness reflection index or the tunnel structure durability reflection index meets the requirements.

[0088] For example, if some parameter values ​​in the stiffness index of a high-risk scheme exceed the standard limit by 10% or some parameter values ​​in the durability index are lower than the design standard by 20%, then the parameters should be adjusted (such as increasing the rise-span ratio of the invert arch or increasing the steel content of the steel section) and recalculated until the requirements are met.

[0089] In the above scheme, the long-term reliability of the design scheme is ensured through multi-scale verification of finite element analysis and accelerated erosion test, filling the technical gap in the multi-index collaborative verification of tunnel structure under composite dissolution and erosion environment.

[0090] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An erosion-resistant tunnel structure, characterized in that, It includes a flexible concrete layer (1), an energy dissipation layer (2), and a rigid concrete layer (3) arranged sequentially from the outside to the inside; the energy dissipation layer (2) includes: A drainage board layer is connected to the flexible concrete layer (1), and the drainage board layer is used to drain water that seeps into the energy dissipation layer (2); A foam buffer layer is disposed on the inner side of the drainage board layer. The foam buffer layer is used to absorb the deformation caused by water absorption of the flexible concrete layer (1). A waterproof membrane layer is disposed inside the foam buffer layer and connected to the rigid concrete layer (3). The waterproof membrane layer is used to block water from entering the rigid concrete layer (3) from the energy dissipation layer (2).

2. The erosion-resistant tunnel structure as described in claim 1, characterized in that, The drainage direction of the drainage board layer is the same as that of the tunnel circumference, and the tunnel is also provided with a drainage ditch (4); the anti-erosion tunnel structure also includes: At least two main drainage pipes (5) are provided, both with the same axial direction as the extension direction of the tunnel. At least one main drainage pipe (5) is provided on each side of the tunnel. The main drainage pipes (5) are connected to the drainage board layer. Multiple drainage branch pipes (6) are spaced apart on the outer periphery of the main drainage pipe (5) in the extension direction of the main drainage pipe (5), and the drainage branch pipes (6) connect the main drainage pipe (5) and the drainage ditch (4).

3. The erosion-resistant tunnel structure as described in claim 1, characterized in that, The erosion-resistant tunnel structure also includes: Multiple anchor bolts (7) are arranged around the outer periphery of the energy dissipation layer (2) and penetrate the flexible concrete layer (1).

4. The erosion-resistant tunnel structure as described in claim 1, characterized in that, The flexible concrete layer (1), the energy dissipation layer (2), and the rigid concrete layer (3) together constitute a structural layer. On a cross section perpendicular to the tunnel extension direction, the structural layer is arc-shaped or ring-shaped. In the direction of gravity, the inner periphery of the tunnel is divided into a bottom area located below and an arched area located above. When the structural layer is arc-shaped, the structural layer is disposed in the arched region; When the structural layer is annular, the structural layer is arranged around the inner periphery of the tunnel.

5. The erosion-resistant tunnel structure as described in claim 1, characterized in that, The flexible concrete layer (1) is mixed with fibers.

6. The erosion-resistant tunnel structure as described in claim 5, characterized in that, The fibers are polypropylene fibers and / or steel fibers.

7. The erosion-resistant tunnel structure as described in claim 1, characterized in that, The rigid concrete layer (3) is provided with steel profiles arranged along the circumference of the tunnel; The steel profile consists of multiple sections arranged at intervals along the extension direction of the tunnel.

8. The erosion-resistant tunnel structure as described in claim 7, characterized in that, The steel profiles arranged along the circumference of the tunnel are divided into multiple sections, which are connected by bolts.

9. The erosion-resistant tunnel structure as described in claim 7, characterized in that, The steel profile is coated with an epoxy resin coating. The dry film thickness of the epoxy resin coating is ≥300μm.

10. The erosion-resistant tunnel structure as described in claim 7, characterized in that, The rigid concrete layer (3) contains slag powder or silica fume.

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