A method for designing parameters of an anti-erosion tunnel

Abstract

This application discloses a design method for erosion-resistant tunnel parameters. The method includes: acquiring tunnel environmental information and the range of tunnel safety indicators; determining the tunnel's catastrophic risk based on the tunnel environmental information; determining the range of tunnel structural parameters based on the catastrophic risk; determining the tunnel structural parameters based on the range of tunnel structural parameters; determining the tunnel safety indicators based on the tunnel structural parameters; and determining or adjusting the tunnel structural parameters based on the comparison results between the tunnel safety indicators and the range of tunnel safety indicators. The erosion-resistant tunnel parameter design method proposed in this application avoids the blindness and arbitrariness in determining the values ​​of structural parameters for tunnels subjected to complex dissolution and erosion of surrounding rock, effectively ensuring the tunnel's stiffness and durability, and reducing the risk of subsequent tunnel structural deterioration.

Description

Technical Field

[0001] This application relates to the field of tunnel parameter design technology, and in particular to a design method for erosion-resistant tunnel parameters. Background Technology

[0002] In tunnel engineering, tunnel structures in sulfate-containing environments face severe corrosion problems caused by sulfate complex solutions. Sulfates corrode the surrounding rock and support structures of tunnels, leading to a decrease in the rigidity and durability of the tunnel structure, which in turn causes a series of problems such as structural deterioration, cracking, and leakage, seriously affecting the normal use and safety of the tunnel.

[0003] In determining the structural parameters of tunnels in complex karst and eroded surrounding rock, it is necessary to ensure that the tunnel structure has sufficient rigidity and durability. However, currently, the tunnel structural parameters are determined based on construction experience, which is blind and arbitrary, lacks scientific and reasonable design methods, makes it difficult to effectively guarantee the rigidity and durability of the tunnel, and poses a greater risk of tunnel structure deterioration in the later stage. Summary of the Invention

[0004] The main purpose of this application is to provide a design method for erosion-resistant tunnel parameters, aiming to solve the problem that traditional surrounding rock tunnel structural parameters lack scientific and reasonable design methods.

[0005] To achieve the above objectives, this application provides a design method for erosion-resistant tunnel parameters. The method includes: acquiring tunnel environmental information and a tunnel safety index range; determining the tunnel's catastrophic risk based on the tunnel environmental information; determining a range of tunnel structural parameters based on the catastrophic risk; determining tunnel structural parameters based on the range of tunnel structural parameters; determining tunnel safety indices based on the tunnel structural parameters; and determining whether to adjust the tunnel structural parameters based on a comparison between the tunnel safety indices and the range of tunnel safety indices.

[0006] Optionally, the tunnel environmental information includes sulfate concentration, surrounding rock permeability coefficient, and surrounding rock stress intensity ratio; determining the tunnel's catastrophic risk based on the tunnel environmental information includes: obtaining sulfate concentration thresholds, surrounding rock permeability coefficient thresholds, and surrounding rock stress intensity ratio thresholds; determining the sulfate concentration level based on the comparison result between the sulfate concentration and the sulfate concentration threshold; determining the surrounding rock permeability coefficient level based on the comparison result between the surrounding rock permeability coefficient and the surrounding rock permeability coefficient threshold; determining the surrounding rock stress intensity ratio level based on the comparison result between the surrounding rock stress intensity ratio and the surrounding rock stress intensity ratio threshold; and determining the tunnel's catastrophic risk based on the sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level, wherein the sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level are all divided into three levels according to the degree of hazard, with level three being the highest degree of hazard.

[0007] Optionally, the surrounding rock stress intensity ratio is determined based on the following formula:

[0008]

[0009] In the formula, Indicates the ratio of stress intensity to surrounding rock; The maximum principal stress borne by a rock mass or rock is expressed in MPa. This indicates the uniaxial compressive strength of rock, in MPa.

[0010] Optionally, determining the catastrophic risk of the tunnel based on the sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level includes: determining the highest hazard level based on the sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level, wherein the highest hazard level is the level with the highest degree of hazard among the sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level; if the highest hazard level is level one, the catastrophic risk of the tunnel is low; if the highest hazard level is level two, and there is only one tunnel environmental information at level two, the catastrophic risk of the tunnel is medium; if the highest hazard level is level three, or there are at least two tunnel environmental information at level two, the catastrophic risk of the tunnel is high.

[0011] Optionally, the tunnel safety indicators include tunnel structural stiffness reflection indicators and tunnel structural durability reflection indicators, and the tunnel safety indicator range includes the tunnel structural stiffness index range and the tunnel structural durability index range. Determining or adjusting the tunnel structural parameters based on the comparison results of the tunnel safety indicators and the tunnel safety indicator range includes: comparing the tunnel structural stiffness reflection indicators with the tunnel structural stiffness index range; comparing the tunnel structural durability reflection indicators with the tunnel structural durability index range; if the tunnel structural stiffness reflection indicators are within the tunnel structural stiffness index range and the tunnel structural durability reflection indicators are within the tunnel structural durability index range, determining the tunnel structural parameters; if the tunnel structural stiffness reflection indicators are outside the tunnel structural stiffness index range, or the tunnel structural durability reflection indicators are outside the tunnel structural durability index range, adjusting the tunnel structural parameters within the tunnel structural parameter range so that the tunnel structural stiffness reflection indicators are within the tunnel structural stiffness index range and the tunnel structural durability reflection indicators are within the tunnel structural durability index range.

[0012] Optionally, the tunnel structure stiffness reflection index includes crown settlement, sidewall displacement, and structural stress concentration factor. The range of the tunnel structure stiffness index includes the range of crown settlement, the range of sidewall displacement, and the range of structural stress concentration factor. The tunnel structure stiffness reflection index is considered to be within the range of the tunnel structure stiffness index only when the crown settlement, the sidewall displacement, and the structural stress concentration factor are all within their respective ranges.

[0013] Optionally, the tunnel structure durability indicators include the concrete sulfate resistance life, the critical time for steel corrosion, and the structural crack propagation rate. The range of the tunnel structure durability indicators includes the range of the concrete sulfate resistance life, the range of the critical time for steel corrosion, and the range of the structural crack propagation rate. The tunnel structure durability indicators are considered to be within the specified range only when the concrete sulfate resistance life, the critical time for steel corrosion, and the structural crack propagation rate are all within their respective ranges.

[0014] Optionally, the tunnel includes a flexible concrete layer, an energy dissipation layer, and a rigid concrete layer arranged sequentially from the outside to the inside; the energy dissipation layer includes a drainage board layer, a foam buffer layer, and a waterproof board layer, with the drainage board layer connected to the flexible concrete layer; the foam buffer layer is disposed inside the drainage board layer; and the waterproof board layer is disposed inside the foam buffer layer and connected to the rigid concrete layer.

[0015] Optionally, the flexible concrete layer is mixed with fibers, and the rigid concrete layer is provided with steel sections arranged along the circumference of the tunnel, with multiple steel sections spaced apart in the extension direction of the tunnel.

[0016] Optionally, the range of tunnel structural parameters includes the range of invert arch rise-to-span ratio, the range of flexible concrete layer thickness, the range of fiber content in flexible concrete layer, the range of drainage board layer thickness, the range of foam buffer layer thickness, the range of waterproof board layer thickness, the range of rigid concrete layer thickness, and the range of steel content.

[0017] This application proposes a method for designing anti-erosion tunnel parameters. Based on tunnel environmental information, the method determines the tunnel's catastrophic risk, then rationally designs a range of tunnel structural parameters based on this risk and assigns values ​​within that range. Next, the method determines the tunnel safety index based on these parameters and checks whether the index falls within the specified range. If it does, the obtained tunnel structural parameters can be implemented; otherwise, the values ​​are adjusted within the specified range until the tunnel safety index falls within it. This method scientifically and rationally yields the values ​​of tunnel structural parameters under different catastrophic risks, avoiding the blindness and arbitrariness in determining the values ​​of structural parameters for tunnels in complex erosion and erosive surrounding rock conditions. It effectively ensures tunnel rigidity and durability, and reduces the risk of later tunnel structural deterioration. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating a method for designing erosion-resistant tunnel parameters according to an embodiment of this application.

[0019] Figure 2 This is a schematic diagram of the tunnel structure in the embodiments of this application. Figure 1 ;

[0020] Figure 3 This is a schematic diagram of the tunnel structure in the embodiments of this application. Figure 2 .

[0021] 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.

[0022] 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

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] refer to Figure 1 This application provides a method for designing parameters for erosion-resistant tunnels, which may include the following steps:

[0028] S100, Obtain tunnel environmental information and tunnel safety index range;

[0029] Among them, tunnel environmental information refers to parameters related to the environment around the tunnel, which may include one or more of the following: sulfate concentration, surrounding rock permeability coefficient, surrounding rock stress intensity ratio, dust concentration, gas concentration, methane concentration, hydrogen sulfide concentration, etc. For example, the higher the sulfate concentration, the more severe the erosion effect on the tunnel; the higher the surrounding rock permeability coefficient, the greater the tunnel seepage, and the more easily the tunnel structure deteriorates.

[0030] In addition, the range of tunnel safety indicators refers to the limitation of the range of changes in various aspects of the tunnel in order to ensure safety during construction and operation. For example, the rigidity and durability of the tunnel structure can be limited. These indicators can be preset based on the experience of professional technicians.

[0031] S200, Determine the disaster risk of the tunnel based on tunnel environmental information;

[0032] Among them, disaster risk refers to the magnitude of the risk of a disaster occurring in the tunnel. For example, it can be divided into low risk, medium risk, or high risk, or it can be classified into levels such as Level 1, Level 2, Level 3, Level 4, etc. The higher the level, the greater the risk of a disaster. The specific level can be determined based on the tunnel environment information. Taking sulfate concentration as an example, the higher the sulfate concentration, the more severe the tunnel erosion, and the greater the risk of a disaster.

[0033] S300, Determining the range of tunnel structural parameters based on the catastrophic risk of the tunnel;

[0034] Taking the disaster risk of tunnels as an example, which is divided into low risk, medium risk or high risk, low risk, medium risk and high risk each correspond to different ranges of tunnel structural parameters. In short, different risk levels correspond to different ranges of tunnel structural parameters. These ranges of tunnel structural parameters can be set in advance by professional technicians based on construction experience.

[0035] Of course, the same parameter can partially intersect within the range of tunnel structural parameters corresponding to different risk levels.

[0036] S400. Determine tunnel structural parameters based on the range of tunnel structural parameters;

[0037] The tunnel structure parameters can be taken from the range of tunnel structure parameters. They can be random values, endpoint values, or intermediate values, etc.

[0038] S500, Determining tunnel safety indicators based on tunnel structural parameters;

[0039] The specific tunnel safety indicators can be one or more of the following: tunnel structure stiffness reflection indicators and tunnel structure durability reflection indicators. The specific indicators can be calculated based on finite element software or corresponding equations. Of course, some indicators can also be set based on the work experience of technical personnel, or further set according to construction requirements.

[0040] S600. Based on the comparison results between tunnel safety indicators and the range of tunnel safety indicators, determine whether to adjust the tunnel structural parameters.

[0041] If the tunnel safety index is within the range of tunnel safety indexes, it indicates that the tunnel structural parameters are reasonable and can be used; if the tunnel safety index is not within the range of tunnel safety indexes, it indicates that the tunnel structural parameters are not reasonable enough and cannot meet the tunnel construction requirements. In this case, the process should return to step S400, redetermine the tunnel structural parameters, and determine the tunnel safety index based on the tunnel structural parameters until the tunnel safety index is within the range of tunnel safety indexes.

[0042] This application proposes a method for designing anti-erosion tunnel parameters. Based on tunnel environmental information, the method determines the tunnel's catastrophic risk, then rationally designs a range of tunnel structural parameters based on this risk and assigns values ​​within that range. Next, the method determines the tunnel safety index based on these parameters and checks whether the index falls within the specified range. If it does, the obtained tunnel structural parameters can be implemented; otherwise, the values ​​are adjusted within the specified range until the tunnel safety index falls within it. This method scientifically and rationally yields the values ​​of tunnel structural parameters under different catastrophic risks, avoiding the blindness and arbitrariness in determining the values ​​of structural parameters for tunnels in complex erosion and erosive surrounding rock conditions. It effectively ensures tunnel rigidity and durability, and reduces the risk of later tunnel structural deterioration.

[0043] In an exemplary embodiment, tunnel environmental information may include sulfate concentration, surrounding rock permeability coefficient, and surrounding rock stress intensity ratio; step S200 may specifically include the following steps:

[0044] S210, obtain the sulfate concentration threshold, the surrounding rock permeability coefficient threshold, and the surrounding rock stress intensity ratio threshold;

[0045] Among them, the sulfate concentration threshold, the surrounding rock permeability coefficient threshold, and the surrounding rock stress intensity ratio threshold can all be preset based on the work experience of technical personnel.

[0046] S220. Determine the sulfate concentration level based on the comparison results between sulfate concentration and sulfate concentration threshold;

[0047] S230. Determine the permeability level of the surrounding rock based on the comparison results between the permeability coefficient of the surrounding rock and the permeability threshold of the surrounding rock;

[0048] S240. Determine the surrounding rock stress intensity ratio level based on the comparison results between the surrounding rock stress intensity ratio and the surrounding rock stress intensity ratio threshold.

[0049] S250, the catastrophic risk of tunnels is determined based on sulfate concentration level, surrounding rock permeability coefficient level, and surrounding rock stress intensity ratio level.

[0050] Among them, the sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level are all divided into three levels according to the degree of hazard, with level three being the most hazard-prone.

[0051] In an exemplary embodiment, the surrounding rock stress intensity ratio is determined based on the following formula:

[0052]

[0053] In the formula, Indicates the ratio of stress intensity to surrounding rock; The maximum principal stress borne by a rock mass or rock is expressed in MPa. This indicates the uniaxial compressive strength of rock, in MPa.

[0054] Specifically, sulfate concentration can be determined by ion chromatography with an accuracy of ±10 mg / L; permeability coefficient is calculated according to Darcy's law; the stress-intensity ratio of surrounding rock is usually defined as "the ratio of the maximum principal stress acting on the medium to the uniaxial compressive strength of the medium".

[0055] 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.

[0056] In step S220, the sulfate concentration threshold may include a first threshold and a second threshold that increase sequentially. When the sulfate concentration is less than the first threshold, the hazard level of the sulfate concentration is level one. When the sulfate concentration is between the first threshold and the second threshold, the hazard level of the sulfate concentration is level two. When the sulfate concentration is greater than the second threshold, the hazard level of the sulfate concentration is level three.

[0057] The first threshold in the specific sulfate concentration threshold can be 1000 mg / L, and the second threshold can be 8000 mg / L.

[0058] For example, sulfate concentrations are divided into three levels, as follows:

[0059] 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.

[0060] 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.

[0061] 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.

[0062] In step S230, the threshold for the surrounding rock permeability coefficient may include a first threshold and a second threshold that increase sequentially. When the surrounding rock permeability coefficient is less than the first threshold, the degree of harm of the surrounding rock permeability coefficient is level one. When the surrounding rock permeability coefficient is between the first threshold and the second threshold, the degree of harm of the surrounding rock permeability coefficient is level two. When the surrounding rock permeability coefficient is greater than the second threshold, the degree of harm of the surrounding rock permeability coefficient is level three.

[0063] The first threshold in the specific surrounding rock permeability coefficient threshold can be 1×10. -7 m / s, the second threshold in the surrounding rock permeability coefficient threshold can be 1×10 -5 m / s.

[0064] For example, the permeability coefficient of the surrounding rock is divided into three levels, as follows:

[0065] Level 1: Permeability coefficient < 1 × 10⁻⁻¹ 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.

[0066] 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.

[0067] Level 3: Permeability coefficient > 1 × 10⁻⁻⁶ 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.

[0068] In step S240, the threshold for the surrounding rock stress intensity ratio may include a first threshold and a second threshold that increase sequentially. When the surrounding rock stress intensity ratio is less than the first threshold, the degree of harm of the surrounding rock stress intensity ratio is level one. When the surrounding rock stress intensity ratio is between the first threshold and the second threshold, the degree of harm of the surrounding rock stress intensity ratio is level two. When the surrounding rock stress intensity ratio is greater than the second threshold, the degree of harm of the surrounding rock stress intensity ratio is level three.

[0069] Specifically, the first threshold in the surrounding rock stress intensity ratio threshold can be 0.3, and the second threshold in the surrounding rock stress intensity ratio threshold can be 0.7.

[0070] For example, the stress intensity of the surrounding rock can be divided into three levels, as follows:

[0071] 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.

[0072] 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.

[0073] 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.

[0074] Specifically, the above methods can be used to determine the hazard level corresponding to the three tunnel environmental information based on the actual sulfate concentration, permeability coefficient, and stress intensity ratio of the surrounding rock, and ultimately determine the catastrophic risk of the tunnel.

[0075] In an exemplary embodiment, step S250 may specifically include the following steps:

[0076] S251. The highest hazard level is determined based on the sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level. The highest hazard level is the level with the highest degree of hazard among the sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level.

[0077] S252. If the highest hazard level is Level 1, the disaster risk of the tunnel is low.

[0078] S253. If the highest hazard level is level two, and there is only one tunnel environmental information at level two, the disaster risk of the tunnel is medium risk.

[0079] S254. If there are at least two tunnel environmental information items with the highest hazard level of Level 3 or Level 2, the tunnel is considered to have a high risk of disaster.

[0080] The highest hazard level is the level with the highest degree of hazard among the sulfate concentration level, surrounding rock permeability coefficient level, and surrounding rock stress intensity ratio level. For example, if the sulfate concentration level is level one, the surrounding rock permeability coefficient level is level two, and the surrounding rock stress intensity ratio level is level two, then the highest hazard level is level two; if the sulfate concentration level is level one, the surrounding rock permeability coefficient level is level three, and the surrounding rock stress intensity ratio level is level one, then the highest hazard level is level three. In other words, the highest hazard level is the level with the highest degree of hazard among the three levels corresponding to the tunnel environmental information, with level three being the highest and level one the lowest.

[0081] In steps S252 to S254, when all three tunnel environmental information are at level one, the tunnel's disaster risk is low; when one tunnel environmental information is at level two and the rest are at level one, the tunnel's disaster risk is medium; when at least one tunnel environmental information is at level three, or when two or more tunnel environmental information are at level two, the tunnel's disaster risk is high.

[0082] In this way, the catastrophic risk of a tunnel can be determined based on the sulfate concentration level, the permeability coefficient level of the surrounding rock, and the stress intensity ratio level of the surrounding rock, and the range of tunnel contact parameters can be determined according to the different catastrophic risks of the tunnel.

[0083] refer to Figure 2 and Figure 3In an exemplary embodiment, the tunnel 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 being connected to the flexible concrete layer 1 and used to drain water that seeps into the energy dissipation layer 2; the foam buffer layer being disposed inside the drainage board layer and used to absorb the deformation caused by water absorption by the flexible concrete layer 1; the waterproof board layer being disposed inside the foam buffer layer and connected to the rigid concrete layer 3 and used to prevent water from entering the rigid concrete layer 3 from the energy dissipation layer 2.

[0084] In use, it breaks through the limitations of traditional single rigid support or single flexible support. The flexible concrete layer 1 has a certain deformation capacity, which effectively improves crack resistance and seepage prevention. The rigid concrete layer 3 has a large structural rigidity to meet the load-bearing requirements. The foam buffer layer is located between the flexible concrete layer 1 and the rigid concrete layer 3 to consume 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 will not seep into the rigid concrete layer 3. The combination of drainage and waterproofing can effectively improve the tunnel's ability to resist solution erosion.

[0085] 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.

[0086] 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.

[0087] refer to Figure 2In 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 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.

[0088] 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.

[0089] Among them, such as Figure 2 As shown, Figure 2 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.

[0090] 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.

[0091] refer to Figure 2 In an exemplary embodiment, the 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.

[0092] 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.

[0093] 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.

[0094] refer to Figure 2 and Figure 3In 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.

[0095] like Figure 2 As 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.

[0096] like Figure 3 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.

[0097] It should be understood that the full-enclosure method involves first lining the bottom area concrete structure, and then using a secondary lining method to construct the arch area concrete structure. 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-closure waterproofing and emergency drainage.

[0098] In an exemplary embodiment, the flexible concrete layer 1 is mixed with fibers; the fibers are polypropylene fibers and / or steel fibers.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] In an exemplary embodiment, the range of tunnel structural parameters may include the range of invert arch rise-to-span ratio, the range of flexible concrete layer thickness, the range of fiber content in flexible concrete layer, the range of drainage board layer thickness, the range of foam buffer layer thickness, the range of waterproof board layer thickness, the range of rigid concrete layer thickness, and the range of steel content.

[0110] Based on the disaster risks of the tunnel, the specific parameter scheme is as follows:

[0111] Low-risk parameter scheme:

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] Medium-risk parameter scheme:

[0117] 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.

[0118] 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.

[0119] 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".

[0120] 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.

[0121] High-risk parameter scheme:

[0122] 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.

[0123] 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.

[0124] 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. -5cm / s, achieving full-enclosed water isolation and emergency drainage.

[0125] 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.

[0126] In low-risk and medium-risk scenarios, a semi-enclosed solution is adopted for the structural layer, such as... Figure 2 As shown, in high-risk situations, the structural layer adopts a fully enclosed solution, such as... Figure 3 As shown.

[0127] It should be noted that the determination of the invert arch rise-to-span ratio needs to comprehensively consider factors such as the stress state of the surrounding rock of the tunnel and the degree of influence of sulfate erosion, so as to ensure that the invert arch can effectively bear the load and improve the overall stability of the tunnel structure.

[0128] In an exemplary embodiment, the tunnel safety index may include a tunnel structure stiffness reflection index and a tunnel structure durability reflection index, and the range of the tunnel safety index may include the range of the tunnel structure stiffness index and the range of the tunnel structure durability index; step S600 may specifically include the following steps:

[0129] S610. Compare the range of tunnel structure stiffness reflection index with the range of tunnel structure stiffness index.

[0130] S620. Compare the durability reflection index of tunnel structure with the range of tunnel structure durability index;

[0131] S630. If the tunnel structure stiffness reflection index is within the range of the tunnel structure stiffness index, and the tunnel structure durability reflection index is within the range of the tunnel structure durability index, determine the tunnel structure parameters.

[0132] S640. If the tunnel structure stiffness reflection index is outside the range of the tunnel structure stiffness index, or the tunnel structure durability reflection index is outside the range of the tunnel structure durability index, adjust the tunnel structure parameters within the range of tunnel structure parameters so that the tunnel structure stiffness reflection index is within the range of the tunnel structure stiffness index and the tunnel structure durability reflection index is within the range of the tunnel structure durability index.

[0133] Specifically, it should be understood that there are three parameter schemes for tunnel structure parameters: low risk, medium risk, and high risk. Correspondingly, there are three ranges of tunnel safety indicators, each corresponding to one of the three schemes for tunnel structure parameters.

[0134] When the tunnel structure stiffness reflection index is within the range of the tunnel structure stiffness index, and the tunnel structure durability reflection index is within the range of the tunnel structure durability index, it can be determined that the tunnel structure parameters meet the engineering requirements, and thus the values ​​of the tunnel structure parameters can be determined.

[0135] When the tunnel structure stiffness reflection index is outside the range of the tunnel structure stiffness index, or the tunnel structure durability reflection index is outside the range of the tunnel structure durability index, the tunnel structure parameters need to be adjusted until the tunnel structure stiffness reflection index is within the range of the tunnel structure stiffness index and the tunnel structure durability reflection index is within the range of the tunnel structure durability index.

[0136] 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.

[0137] In an exemplary embodiment, the tunnel structure stiffness reflection index may include the crown settlement, the sidewall displacement, and the structural stress concentration factor. The range of the tunnel structure stiffness index may include the range of crown settlement, the range of sidewall displacement, and the range of structural stress concentration factor. The tunnel structure stiffness reflection index is within the range of the tunnel structure stiffness index only when the crown settlement, the sidewall displacement, and the structural stress concentration factor are all within their respective ranges.

[0138] It should be noted that the stiffness index of the tunnel structure can be determined by calculating parameters such as the deformation and stress distribution of the tunnel structure.

[0139] Specifically, stiffness index calculations can be performed 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.

[0140] For example, a high-risk scheme may require the arch settlement to be ≤0.3mm, the sidewall displacement to be ≤0.5mm, and the stress concentration factor to be ≤1.8. The specific requirements for stiffness response indicators can be formulated according to the actual situation.

[0141] In an exemplary embodiment, the durability indicators of a tunnel structure may include the sulfate resistance life of concrete, the critical time for steel corrosion, and the crack propagation rate of the structure. The range of the tunnel structure durability indicators may include the range of the sulfate resistance life of concrete, the critical time for steel corrosion, and the range of the crack propagation rate of the structure. The tunnel structure durability indicators are considered to be within the range of tunnel structure durability indicators only when the sulfate resistance life of concrete, the critical time for steel corrosion, and the crack propagation rate of the structure are all within their respective ranges.

[0142] Among them, the durability index of tunnel structure can be determined by calculating parameters such as the sulfate resistance of concrete and the corrosion rate of steel bars.

[0143] Specifically, durability performance indicators can be calculated using the Nernst equation combined with accelerated erosion tests to determine the concrete's sulfate resistance life, the critical time for steel corrosion, and the rate of structural crack propagation.

[0144] For example, under the three tunnel structure parameter schemes with different risks, the concrete is required to have a sulfate erosion resistance life of ≥100 years, a steel reinforcement corrosion critical time of ≥80 years, and a structural crack propagation rate of ≤0.02 mm / year; here the concrete includes flexible concrete layer 1 and rigid concrete layer 3.

[0145] 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.

[0146] In the above scheme, the long-term reliability of the design parameters is ensured through multi-scale verification of finite element analysis and accelerated erosion tests, filling the technical gap in the collaborative verification of multiple indicators of tunnel structures under composite dissolution and erosion environments.

[0147] 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. A method for designing parameters for erosion-resistant tunnels, characterized in that, include: Obtain tunnel environmental information and tunnel safety index ranges, wherein the tunnel environmental information includes sulfate concentration, surrounding rock permeability coefficient and surrounding rock stress intensity ratio, and the tunnel safety index range includes tunnel structural stiffness index range and tunnel structural durability index range. The disaster risk of the tunnel is determined based on the tunnel environment information; The range of tunnel structural parameters is determined based on the catastrophic risk of the tunnel. The tunnel structural parameters are determined based on the range of tunnel structural parameters. The tunnel safety index is determined based on the tunnel structural parameters, wherein the tunnel safety index includes the tunnel structural stiffness reflection index and the tunnel structural durability reflection index. Whether to adjust the tunnel structural parameters is determined based on the comparison results between the tunnel safety index and the range of the tunnel safety index; The determination of tunnel disaster risks based on the tunnel environment information includes: Obtain the sulfate concentration threshold, the surrounding rock permeability coefficient threshold, and the surrounding rock stress intensity ratio threshold; The sulfate concentration level is determined based on the comparison between the sulfate concentration and the sulfate concentration threshold. The permeability level of the surrounding rock is determined based on the comparison between the permeability coefficient of the surrounding rock and the permeability threshold of the surrounding rock. The surrounding rock stress intensity ratio level is determined based on the comparison result between the surrounding rock stress intensity ratio and the surrounding rock stress intensity ratio threshold. The catastrophic risk of the tunnel is determined based on the sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level. The sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level are all classified into three levels according to the degree of hazard, with level three being the most hazard-prone. The process of determining or adjusting the tunnel structural parameters based on the comparison results between the tunnel safety index and the range of the tunnel safety index includes: Compare the tunnel structure stiffness reflection index with the range of the tunnel structure stiffness index; Compare the tunnel structure durability reflection index with the range of the tunnel structure durability index; If the tunnel structure stiffness reflection index is within the range of the tunnel structure stiffness index, and the tunnel structure durability reflection index is within the range of the tunnel structure durability index, then the tunnel structure parameters are determined. If the tunnel structure stiffness reflection index is outside the range of the tunnel structure stiffness index, or the tunnel structure durability reflection index is outside the range of the tunnel structure durability index, the tunnel structure parameters are adjusted within the range of the tunnel structure parameters so that the tunnel structure stiffness reflection index and the tunnel structure durability reflection index are both within the range of the tunnel structure durability index.

2. The design method for erosion-resistant tunnel parameters as described in claim 1, characterized in that, The surrounding rock stress intensity ratio is determined based on the following formula: In the formula, Indicates the ratio of stress intensity to surrounding rock; This indicates the maximum principal stress borne by the rock mass or rock. It represents the uniaxial compressive strength of rock.

3. The design method for erosion-resistant tunnel parameters as described in claim 1, characterized in that, The determination of the tunnel's catastrophic risk based on the sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level includes: The highest hazard level is determined based on the sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level, wherein the highest hazard level is the level with the highest degree of hazard among the sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level. If the highest hazard level is Level 1, the disaster risk of the tunnel is low. If the highest hazard level is level two, and there is only one tunnel environmental information at level two, the disaster risk of the tunnel is medium risk. If there are at least two instances of tunnel environmental information with the highest hazard level being Level 3 or Level 2, the tunnel is considered to have a high risk of disaster.

4. The design method for erosion-resistant tunnel parameters as described in claim 1, characterized in that, The tunnel structure stiffness reflection index includes crown settlement, sidewall displacement, and structural stress concentration factor. The range of the tunnel structure stiffness index includes the range of crown settlement, the range of sidewall displacement, and the range of structural stress concentration factor. Specifically, the tunnel structure stiffness reflection index is within the range of the tunnel structure stiffness index only when the arch settlement, the sidewall displacement, and the structural stress concentration coefficient are all within their respective ranges.

5. The design method for erosion-resistant tunnel parameters as described in claim 1, characterized in that, The durability indicators of the tunnel structure include the sulfate resistance life of concrete, the critical time for steel corrosion, and the crack propagation rate of the structure. The range of the tunnel structure durability indicators includes the range of sulfate resistance life of concrete, the range of critical time for steel corrosion, and the range of crack propagation rate of the structure. Specifically, the tunnel structure durability index is within the range of the following conditions: the concrete's sulfate resistance life, the steel reinforcement corrosion critical time, and the structural crack propagation rate are all within their respective ranges.

6. The method for designing erosion-resistant tunnel parameters as described in claim 1, characterized in that, The tunnel comprises, from the outside in, a flexible concrete layer (1), an energy dissipation layer (2), and a rigid concrete layer (3); the energy dissipation layer (2) includes: A drainage board layer is connected to the flexible concrete layer (1); A foam buffer layer is disposed on the inner side of the drainage board layer; A waterproof membrane layer is disposed inside the foam buffer layer and connected to the rigid concrete layer (3).

7. The design method for erosion-resistant tunnel parameters as described in claim 6, characterized in that, The flexible concrete layer (1) is mixed with fibers, and the rigid concrete layer (3) is provided with steel profiles arranged along the circumference of the tunnel. There are multiple steel profiles and they are spaced apart in the extension direction of the tunnel.

8. The design method for erosion-resistant tunnel parameters as described in claim 7, characterized in that, The range of tunnel structural parameters includes the range of invert arch rise-to-span ratio, range of flexible concrete layer thickness, range of fiber content in flexible concrete layer, range of drainage board layer thickness, range of foam buffer layer thickness, range of waterproof board layer thickness, range of rigid concrete layer thickness, and range of steel content.

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