Design method of anti-erosion tunnel parameters

Abstract

The invention discloses a design method for anti-erosion tunnel parameters. The design method comprises the steps that tunnel environment information and a tunnel safety index range are acquired; determining a catastrophe risk of the tunnel based on the tunnel environment information; determining a tunnel structure parameter range based on the catastrophe risk of the tunnel; determining tunnel structure parameters based on the tunnel structure parameter range; determining tunnel safety indexes based on the tunnel structure parameters; and determining or adjusting tunnel structure parameters based on a comparison result of the tunnel safety index and the tunnel safety index range. According to the design method of the anti-erosion tunnel parameters, blindness and randomness of composite corrosion and erosion surrounding rock tunnel structure parameter values are avoided, the tunnel rigidity and durability are effectively guaranteed, and the later tunnel structure degradation risk is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel parameter design, and particularly relates to a design method of anti-erosion tunnel parameters. BACKGROUND

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

[0003] In the determination of the structure parameters of the composite solution-eroded and erosion-surrounded rock tunnel, it is necessary to ensure that the tunnel structure has sufficient stiffness and durability. At present, the tunnel structure parameters are determined according to construction experience, which is blind and arbitrary, lacks a scientific and reasonable design method, and cannot effectively ensure the stiffness and durability of the tunnel, so that the tunnel structure is prone to deterioration in the later period. SUMMARY

[0004] The main purpose of the present application is to provide a design method of anti-erosion tunnel parameters, which aims to solve the problem of lack of scientific and reasonable design method for traditional surrounding rock tunnel structure parameters.

[0005] To achieve the above-mentioned purpose, the present application provides a design method of anti-erosion tunnel parameters, which comprises: obtaining tunnel environment information and a tunnel safety index range; determining a disaster risk of the tunnel based on the tunnel environment information; determining a tunnel structure parameter range based on the disaster risk of the tunnel; determining a tunnel structure parameter based on the tunnel structure parameter range; determining a tunnel safety index based on the tunnel structure parameter; and determining whether to adjust the tunnel structure parameter based on the comparison result of the tunnel safety index and the tunnel safety index range.

[0006] Optionally, the tunnel environment information comprises sulfate concentration, surrounding rock permeability coefficient and surrounding rock stress intensity ratio; the determination of the disaster risk of the tunnel based on the tunnel environment information comprises: obtaining a sulfate concentration threshold value, a surrounding rock permeability coefficient threshold value and a surrounding rock stress intensity ratio threshold value; determining a sulfate concentration grade based on the comparison result of the sulfate concentration and the sulfate concentration threshold value; determining a surrounding rock permeability coefficient grade based on the comparison result of the surrounding rock permeability coefficient and the surrounding rock permeability coefficient threshold value; determining a surrounding rock stress intensity ratio grade based on the comparison result of the surrounding rock stress intensity ratio and the surrounding rock stress intensity ratio threshold value; and determining the disaster risk of the tunnel based on the sulfate concentration grade, the surrounding rock permeability coefficient grade and the surrounding rock stress intensity ratio grade, wherein the sulfate concentration grade, the surrounding rock permeability coefficient grade and the surrounding rock stress intensity ratio grade are all divided into first to third levels according to the degree of harm, and the third level has the highest degree of harm.

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

[0008] wherein, represents the stress intensity ratio of the surrounding rock; represents the maximum principal stress borne by the rock mass or rock, in units of MPa; represents the uniaxial compressive strength of the rock, in units of MPa.

[0009] Optionally, the determining the catastrophe risk of the tunnel based on the sulfate concentration grade, the permeability coefficient grade of the surrounding rock, and the stress intensity ratio of the surrounding rock comprises: determining a highest hazard grade based on the sulfate concentration grade, the permeability coefficient grade of the surrounding rock, and the stress intensity ratio of the surrounding rock, wherein the highest hazard grade is the grade with the highest hazard degree among the sulfate concentration grade, the permeability coefficient grade of the surrounding rock, and the stress intensity ratio of the surrounding rock; if the highest hazard grade is grade one, the catastrophe risk of the tunnel is low; if the highest hazard grade is grade two, and there is only one tunnel environment information in grade two, the catastrophe risk of the tunnel is medium; if the highest hazard grade is grade three or there are at least two tunnel environment information in grade two, the catastrophe risk of the tunnel is high.

[0010] Optionally, the tunnel safety index comprises a tunnel structure stiffness reflection index and a tunnel structure durability reflection index, and the tunnel safety index range comprises a tunnel structure stiffness index range and a tunnel structure durability index range; the determining or adjusting the tunnel structure parameter based on the comparison result of the tunnel safety index and the tunnel safety index range comprises: comparing the tunnel structure stiffness reflection index with the tunnel structure stiffness index range; comparing the tunnel structure durability reflection index with the tunnel structure durability index range; if the tunnel structure stiffness reflection index is within the tunnel structure stiffness index range and the tunnel structure durability reflection index is within the tunnel structure durability index range, determining the tunnel structure parameter; if the tunnel structure stiffness reflection index is outside the tunnel structure stiffness index range or the tunnel structure durability reflection index is outside the tunnel structure durability index range, adjusting the tunnel structure parameter within the tunnel structure parameter range, so that the tunnel structure stiffness reflection index is within the tunnel structure stiffness index range and the tunnel structure durability reflection index is within the tunnel structure durability index range.

[0011] Optionally, the tunnel structure stiffness reflection index comprises vault subsidence, side wall displacement and structure stress concentration coefficient, and the tunnel structure stiffness index range comprises a vault subsidence range, a side wall displacement range and a structure stress concentration coefficient range; wherein, only when the vault subsidence, the side wall displacement and the structure stress concentration coefficient are all within the corresponding ranges, the tunnel structure stiffness reflection index is within the tunnel structure stiffness index range.

[0012] Optionally, the tunnel structure durability reflection index comprises concrete sulfate attack resistance life, steel corrosion critical time and structure crack propagation rate, and the tunnel structure durability index range comprises a concrete sulfate attack resistance life range, a steel corrosion critical time range and a structure crack propagation rate range; wherein, only when the concrete sulfate attack resistance life, the steel corrosion critical time and the structure crack propagation rate are all within the corresponding ranges, the tunnel structure durability reflection index is within the tunnel structure durability index range.

[0013] Optionally, the tunnel 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; the foam buffer layer is arranged on the inner side of the drainage board layer; the waterproof board layer is arranged on the inner side of the foam buffer layer and connected with the rigid concrete layer.

[0014] Optionally, the flexible concrete layer is mixed with fibers, and the rigid concrete layer is provided with profile steel arranged along the circumferential direction of the tunnel, the profile steel has multiple and is arranged at intervals in the extension direction of the tunnel.

[0015] Optionally, the tunnel structure parameter range comprises an invert rise-span ratio range, a flexible concrete layer thickness range, a flexible concrete layer fiber mixing amount range, a drainage board layer thickness range, a foam buffer layer thickness range, a waterproof board layer thickness range, a rigid concrete layer thickness range and a profile steel content rate range.

[0016] The design method of the anti-erosion tunnel parameter provided by the embodiment of the application determines the disaster risk of the tunnel according to the tunnel environment information, reasonably designs the tunnel structure parameter range based on the disaster risk and takes values within the range, then determines the tunnel safety index according to the tunnel structure parameter, judges whether the tunnel safety index is within the tunnel safety index range, if yes, the obtained tunnel structure parameter can be determined to be implemented, if not, the value should be adjusted within the tunnel structure parameter range until the tunnel safety index is within the tunnel safety index range, so that the value of the tunnel structure parameter under different disaster risks can be obtained scientifically and reasonably, the blindness and randomness of the value of the tunnel structure parameter of the compound dissolution and erosion surrounding rock are avoided, the tunnel stiffness and durability are effectively ensured, and the later tunnel structure degradation risk is reduced. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating a method for designing erosion-resistant tunnel parameters according to an embodiment of this application. Figure 2 This is a schematic diagram of the tunnel structure in the embodiments of this application. Figure 1 ; Figure 3 This is a schematic diagram of the tunnel structure in the embodiments of this application. Figure 2 .

[0018] 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.

[0019] 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

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] refer to Figure 1 This application provides a method for designing parameters for erosion-resistant tunnels, which may include the following steps: S100, Obtain tunnel environmental information and tunnel safety index range; 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.

[0025] 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.

[0026] S200, Determine the disaster risk of the tunnel based on tunnel environmental information; 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.

[0027] S300, Determining the range of tunnel structural parameters based on the catastrophic risk of the tunnel; For example, if the disaster risk of the tunnel is classified as low risk, medium risk or high risk, the low risk, medium risk and high risk each correspond to a different range of tunnel structure parameters. In general, different risk levels correspond to different ranges of tunnel structure parameters, which can be set by professional technicians in advance according to construction experience.

[0028] Of course, the same parameter can partially intersect in the range of tunnel structure parameters corresponding to different risk levels.

[0029] S400, determining a tunnel structure parameter based on the range of tunnel structure parameters; The tunnel structure parameter can be randomly selected from the range of tunnel structure parameters, or the end value, or the intermediate value, etc.

[0030] S500, determining a tunnel safety index based on the tunnel structure parameter; The specific tunnel safety index can be one or more of the tunnel structure stiffness reflection index and the tunnel structure durability reflection index, etc. The specific index can be calculated according to the finite element software or the corresponding equation. Of course, some indexes can also be set according to the working experience of technicians, or further set according to the construction requirements.

[0031] S600, determining whether to adjust the tunnel structure parameter based on the comparison result of the tunnel safety index and the range of tunnel safety index.

[0032] If the tunnel safety index is within the range of tunnel safety index, it means that the tunnel structure parameter is reasonable and can be used. If the tunnel safety index is not within the range of tunnel safety index, it means that the tunnel structure parameter is not reasonable enough to meet the tunnel construction requirements, and the step S400 should be returned to determine the tunnel structure parameter again, and the tunnel safety index is determined based on the tunnel structure parameter until the tunnel safety index is within the range of tunnel safety index.

[0033] The design method of the anti-erosion tunnel parameter provided by the embodiment of the application determines the disaster risk of the tunnel according to the tunnel environment information, reasonably designs the range of tunnel structure parameters based on the disaster risk, and takes values within the range. Then, the tunnel safety index is determined based on the tunnel structure parameter, and it is judged whether the tunnel safety index is within the range of tunnel safety index. If it is, the obtained tunnel structure parameter can be determined to be implemented. If it is not, the value should be adjusted within the range of tunnel structure parameters until the tunnel safety index is within the range of tunnel safety index. In this way, the value of the tunnel structure parameter under different disaster risks can be scientifically and reasonably obtained, avoiding the blindness and randomness of the value of the tunnel structure parameter of the compound corrosion and erosion surrounding rock, effectively ensuring the tunnel stiffness and durability, and reducing the risk of tunnel structure degradation in the later period.

[0034] In the example embodiment, the tunnel environment information can include sulfate concentration, surrounding rock permeability coefficient, and surrounding rock stress intensity ratio; and step S200 can specifically include the following steps: S210, obtaining a sulfate concentration threshold value, a surrounding rock permeability coefficient threshold value, and a surrounding rock stress intensity ratio threshold value; The sulfate concentration threshold value, the surrounding rock permeability coefficient threshold value, and the surrounding rock stress intensity ratio threshold value can all be set in advance according to the working experience of the technicians.

[0035] S220, determining a sulfate concentration grade based on a comparison result of the sulfate concentration and the sulfate concentration threshold value; S230, determining a surrounding rock permeability coefficient grade based on a comparison result of the surrounding rock permeability coefficient and the surrounding rock permeability coefficient threshold value; S240, determining a surrounding rock stress intensity ratio grade based on a comparison result of the surrounding rock stress intensity ratio and the surrounding rock stress intensity ratio threshold value; S250, determining a disaster risk of the tunnel based on the sulfate concentration grade, the surrounding rock permeability coefficient grade, and the surrounding rock stress intensity ratio grade.

[0036] The sulfate concentration grade, the surrounding rock permeability coefficient grade, and the surrounding rock stress intensity ratio grade are all divided into levels one to three according to the degree of harm, with the third level being the highest.

[0037] In the example embodiment, the surrounding rock stress intensity ratio is determined based on the following formula:

[0038] In the formula, denotes the surrounding rock stress intensity ratio; denotes the maximum principal stress borne by the rock mass or rock, with the unit being MPa; denotes the uniaxial compressive strength of the rock, with the unit being MPa.

[0039] Specifically, the sulfate concentration can be determined by ion chromatography with an accuracy of ±10 mg / L; the permeability coefficient is calculated according to Darcy's law; and 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.

[0040] 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 or hydraulic fracturing method) or numerical simulation calculation; and the uniaxial compressive strength of the rock can be determined through laboratory test (axial compression of standard rock sample under no lateral restraint condition until failure), reflecting the compressive capacity of the rock itself.

[0041] In step S220, the sulfate concentration threshold value can include a first threshold value and a second threshold value that are sequentially increased, when the sulfate concentration is less than the first threshold value, the harm degree of the sulfate concentration is level one, when the sulfate concentration is between the first threshold value and the second threshold value, the harm degree of the sulfate concentration is level two, and when the sulfate concentration is greater than the second threshold value, the harm degree of the sulfate concentration is level three.

[0042] The first threshold value in the specific sulfate concentration threshold value can be 1000 mg / L, and the second threshold value in the sulfate concentration threshold value can be 8000 mg / L.

[0043] For example, the sulfate concentration is divided into three levels, which are as follows: Level one: sulfate concentration < 1000 mg / L, the environment water is mainly physical erosion, the chemical corrosion is weak, and the concrete structure only has slight carbonization or surface weathering.

[0044] Level two: 1000 mg / L ≤ sulfate concentration ≤ 8000 mg / L, the ettringite and gypsum type swelling damage coexist, the gypsum type damage is mainly when the pH value < 11.5, the internal porosity of the concrete increases, and the strength gradually decreases.

[0045] Level three: sulfate concentration > 8000 mg / L, the gypsum type swelling damage mainly occurs, the hydration calcium silicate gel is decomposed to cause the cementitious loss, the concrete is seriously peeled off and cracked, and the structure bearing capacity significantly decreases.

[0046] In step S230, the surrounding rock permeability coefficient threshold value can include a first threshold value and a second threshold value that are sequentially increased, when the surrounding rock permeability coefficient is less than the first threshold value, the harm degree of the surrounding rock permeability coefficient is level one, when the surrounding rock permeability coefficient is between the first threshold value and the second threshold value, the harm degree of the surrounding rock permeability coefficient is level two, and when the surrounding rock permeability coefficient is greater than the second threshold value, the harm degree of the surrounding rock permeability coefficient is level three.

[0047] The first threshold value in the specific surrounding rock permeability coefficient threshold value can be 1×10 -7 m / s, and the second threshold value in the surrounding rock permeability coefficient threshold value can be 1×10 -5 m / s.

[0048] For example, the surrounding rock permeability coefficient is divided into three levels, which are as follows: Level one: permeability coefficient < 1×10 7 m / s, the permeability of the surrounding rock is extremely weak, and the groundwater is difficult to seep into the tunnel.

[0049] Level two: 1×10 7 m / s ≤ permeability coefficient ≤ 1×10 5 m / s, the groundwater seepage speed is moderate, and may cause local leakage or water pressure rise.

[0050] Class III: permeability coefficient > 1 x 10- 7cm / s 5 m / s, the groundwater permeability is strong, and disasters such as water and mud inrush, quicksand, etc. are prone to occur.

[0051] In step S240, the threshold of the stress intensity ratio of surrounding rock can include a first threshold and a second threshold that increase in turn. When the stress intensity ratio of surrounding rock is less than the first threshold, the damage degree of the stress intensity ratio of surrounding rock is class I; when the stress intensity ratio of surrounding rock is between the first threshold and the second threshold, the damage degree of the stress intensity ratio of surrounding rock is class II; and when the stress intensity ratio of surrounding rock is greater than the second threshold, the damage degree of the stress intensity ratio of surrounding rock is class III.

[0052] The first threshold in the specific stress intensity ratio threshold of surrounding rock can be 0.3, and the second threshold in the stress intensity ratio threshold of surrounding rock can be 0.7.

[0053] For example, the stress intensity ratio of surrounding rock is divided into three grades, as follows: Class I: stress intensity ratio < 0.3, at this time the surrounding rock is in the elastic deformation stage, the overall stability is good after excavation, the internal stress does not exceed the elastic limit of rock, and geological disasters such as rock burst and collapse are not prone to occur.

[0054] Class II: 0.3 ≤ stress intensity ratio ≤ 0.7, the surrounding rock enters the plastic deformation stage, the stress in the local area exceeds the yield strength of rock, and piece help, small range of block or slight collapse may occur.

[0055] Class III: stress intensity ratio > 0.7, the surrounding rock is in a strong stress state, the internal stress is close to or exceeds the uniaxial compressive strength of rock, and severe rock burst, large-scale deformation (such as soft rock large deformation) or overall instability are prone to occur.

[0056] Specifically, the above-mentioned manner can be used to determine the damage degree grade corresponding to each of the three tunnel environment information according to the actual sulfate concentration of the tunnel surrounding rock, the permeability coefficient of the surrounding rock, and the stress intensity ratio of the surrounding rock, and finally determine the disaster risk of the tunnel.

[0057] In the example embodiment, step S250 can specifically include the following steps: S251, determining the highest damage grade based on the sulfate concentration grade, the surrounding rock permeability coefficient grade, and the stress intensity ratio grade of surrounding rock, wherein the highest damage grade is the grade with the highest damage degree among the sulfate concentration grade, the surrounding rock permeability coefficient grade, and the stress intensity ratio grade of surrounding rock; S252, if the highest damage grade is class I, the disaster risk of the tunnel is low risk; S253, if the highest damage grade is class II, and there is only one tunnel environment information in class II, the disaster risk of the tunnel is medium risk; S254, if the highest hazard level is level three or at least two tunnel environment information is level two, the tunnel disaster risk is high risk.

[0058] The highest hazard level is the highest level among the levels of the sulfate concentration level, the surrounding rock permeability coefficient level, and the 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, 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, the highest hazard level is level three. That is, the highest hazard level is the highest level among the levels of the three tunnel environment information, and the highest level is level three and the lowest level is level one.

[0059] In steps S252-S254, when the three tunnel environment information are all level one, the tunnel disaster risk is low risk. When one tunnel environment information is level two and the rest are level one, the tunnel disaster risk is medium risk. When at least one tunnel environment information is level three or two or more tunnel environment information is level two, the tunnel disaster risk is high risk.

[0060] Thus, the tunnel disaster risk can be determined based on the sulfate concentration level, the surrounding rock permeability coefficient level, and the surrounding rock stress intensity ratio level, and the tunnel contact parameter range can be determined according to different tunnel disaster risks.

[0061] Reference Figure 2 and Figure 3 In an example embodiment, the tunnel can include a flexible concrete layer 1, an energy dissipation layer 2, and a rigid concrete layer 3 arranged in sequence from outside to inside. The energy dissipation layer 2 can include a drainage board layer, a foam buffer layer, and a waterproof board layer. The drainage board layer is connected with the flexible concrete layer 1 and is used to drain water seeping into the energy dissipation layer 2. The foam buffer layer is arranged inside the drainage board layer and is used to absorb the deformation amount of the flexible concrete layer 1 caused by water absorption. The waterproof board layer is arranged inside the foam buffer layer and is connected with the rigid concrete layer 3, and is used to prevent water from entering the rigid concrete layer 3 from the energy dissipation layer 2.

[0062] In use, the flexible concrete layer 1 has a certain deformation capacity, effectively improving the anti-cracking performance and the anti-seepage effect, while the rigid concrete layer 3 has a large structural rigidity to meet the bearing demand. The foam buffer layer is located between the flexible concrete layer 1 and the rigid concrete layer 3 to consume the deformation amount 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 seeping 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 ability to resist solution erosion.

[0063] It should be noted that the present application adopts the flexible concrete layer 1, the foam buffer layer in the energy dissipation layer 2 and the rigid concrete layer 3 to form a ternary synergistic system of flexible outer layer, transition middle layer and rigid inner layer, and through the stress redistribution mechanism of rigid-flexible interface, the structure can still maintain more than 60% of the bearing capacity when the material is deteriorated due to sulfate attack, and the limitations of brittle fracture of the traditional scheme using rigid support structure and insufficient rigidity of the single flexible support structure are solved.

[0064] In addition, in the energy dissipation layer 2, the outer layer is a drainage plate layer, which can effectively drain the liquid seeping from the flexible concrete layer 1, the middle layer is a foam buffer layer, and the inner layer is a waterproof plate layer, which effectively isolates the liquid and prevents the liquid from passing through the drainage plate and the foam buffer layer to reach the rigid concrete layer 3. In this way, a drainage and waterproof protection system is formed, which improves the anti-erosion efficiency by more than 30% compared with the traditional single drainage or single waterproof design; wherein the liquid is a sulfate solution or groundwater.

[0065] Reference Figure 2 In the example embodiment, the drainage direction of the drainage plate layer is the same as the circumferential direction of the tunnel, and a drainage ditch 4 is further arranged inside the tunnel. The tunnel structure can further include at least two drainage main pipes 5 and a plurality of drainage branch pipes 6. The axial directions of the at least two drainage main pipes 5 are the same as the extension direction of the tunnel, and at least one drainage main pipe 5 is arranged on each side of the tunnel. The drainage main pipe 5 is in communication with the drainage plate layer. The plurality of drainage branch pipes 6 are arranged on the outer periphery of the drainage main pipe 5 in the extension direction of the drainage main pipe 5, and the drainage branch pipe 6 communicates the drainage main pipe 5 with the drainage ditch 4.

[0066] It should be understood that a plurality of drainage grooves can be arranged on the drainage plate layer, and the extension direction of the drainage grooves is the same as the circumferential direction of the tunnel. The plurality of drainage grooves are arranged in sequence in the extension direction of the tunnel. In this way, a drainage channel can be formed on the drainage plate layer, and the direction of liquid flow in the drainage channel is the drainage direction of the drainage plate layer.

[0067] As shown in FIG. 1, the energy dissipation layer 2 is arranged between the flexible concrete layer 1 and the rigid concrete layer 3, and the energy dissipation layer 2 is arranged in the form of a plurality of energy dissipation units 2a arranged in sequence in the extension direction of the tunnel. Figure 2 As shown in FIG. 1, the energy dissipation layer 2 is arranged between the flexible concrete layer 1 and the rigid concrete layer 3, and the energy dissipation layer 2 is arranged in the form of a plurality of energy dissipation units 2a arranged in sequence in the extension direction of the tunnel. Figure 2 As shown in FIG. 1, the energy dissipation layer 2 is arranged between the flexible concrete layer 1 and the rigid concrete layer 3, and the energy dissipation layer 2 is arranged in the form of a plurality of energy dissipation units 2a arranged in sequence in the extension direction of the tunnel.

[0068] It should be understood that the extension direction of the drainage main pipe 5 is the same as the extension direction of the drainage ditch 4 and the extension direction of the tunnel, and then the drainage branch pipe 6 can be provided with a plurality of drainage branch pipes 6 which are distributed in the extension direction of the tunnel to communicate the drainage main pipe 5 and the drainage ditch 4. Among them, the more dense the arrangement of the plurality of drainage branch pipes 6 in the extension direction of the tunnel, the better the drainage effect.

[0069] Reference Figure 2 In the example embodiment, the tunnel structure can further include a plurality of anchor rods 7 which are arranged around the outer periphery of the energy dissipation layer 2 and penetrate the flexible concrete layer 1.

[0070] Specifically, the overall stability of the surrounding rock can be effectively enhanced by arranging a plurality of anchor rods 7 around the tunnel. In addition, the anchor rods 7 distributed around the circumference of the tunnel can form a reinforced arch to improve the load-bearing capacity of the entire support structure.

[0071] It should be understood that the anchor rods 7 distributed around the circumference of the tunnel are referred to as a group of rods, and there are multiple groups of rods which are distributed in the extension direction of the tunnel.

[0072] Reference Figure 3 And Figure 2 In the example embodiment, the flexible concrete layer 1, the energy dissipation layer 2 and the rigid concrete layer 3 form a structural layer as a whole. In the cross section perpendicular to the extension direction of the tunnel, 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 region located below and an arch region located above. When the structural layer is arc-shaped, the structural layer is arranged at the arch region. When the structural layer is ring-shaped, the structural layer is arranged around the inner periphery of the tunnel.

[0073] As Figure 3 shown, when the concentration of sulfate at the tunnel is not high and the water permeability of the surrounding rock of the tunnel is weak, the structural layer is arc-shaped and is arranged only at the arch region of the tunnel, which can effectively protect and resist sulfate erosion. This kind of structural layer support method is referred to as half-enclosed.

[0074] As Figure 2 shown, when the concentration of sulfate at the tunnel is high and the water permeability of the surrounding rock of the tunnel is strong, the structural layer is ring-shaped, i.e. the structural layer is arranged around the circumference of the tunnel, which can effectively protect and resist sulfate erosion. This kind of structural layer support method is referred to as full-enclosed.

[0075] It should be understood that in the full-enclosed mode, the concrete structure of the bottom region can be lined first, and then the concrete structure of the arch region can be made by using the secondary lining method. In the connection area between the energy dissipation layer 2 in the arch region concrete structure and the energy dissipation layer 2 in the bottom region concrete structure, a grouting waterproof ring can be added to ensure the sealing property and prevent liquid from seeping out, so as to achieve full-closed water isolation and emergency drainage.

[0076] In the example embodiment, the flexible concrete layer 1 is mixed with fibers; the fibers are polypropylene fibers and / or steel fibers.

[0077] Specifically, mixing fibers in the flexible concrete layer 1 can effectively improve the ductility of the concrete, ensure that the flexible concrete layer 1 has a certain ductility, and meet the anti-cracking requirement.

[0078] The fibers can be polypropylene fibers and / or steel fibers; the polypropylene fibers can significantly improve the impermeability of the concrete to prevent water penetration; and the steel fibers can significantly improve the compression resistance, bending resistance and tensile fatigue resistance of the concrete, and further improve the service life of the flexible concrete layer 1.

[0079] In the example embodiment, the rigid concrete layer 3 is provided with profile steel arranged along the circumference of the tunnel; the profile steel has multiple profiles and is arranged at intervals in the extension direction of the tunnel.

[0080] Specifically, the profile steel can be an I-beam, which is arranged around the tunnel to improve the structural strength of the rigid concrete layer 3.

[0081] It should be understood that the profile steel arranged along the circumference of the tunnel is divided into multiple sections, and the sections are connected by bolts, which facilitates transportation of the sections and assembly in the tunnel, and the construction is more convenient.

[0082] It should be noted that in the extension direction of the tunnel, the multiple profile steels are arranged at intervals, and the smaller the interval of the profile steels, the higher the structural strength of the rigid concrete layer 3.

[0083] In the example embodiment, the profile steel is wrapped with an epoxy resin coating; the dry film thickness of the epoxy resin coating is ≥300 μm.

[0084] Specifically, the epoxy resin coating can effectively isolate the profile steel from the external environment, prevent the profile steel from being eroded by liquid, oxygen and other substances, and effectively improve the service life of the profile steel.

[0085] The dry film thickness of the epoxy resin coating is ≥300 μm, which can further improve the corrosion resistance of the epoxy resin coating, and prolong the service life of the rigid concrete layer 3 by more than 50 years compared with traditional concrete.

[0086] In the example embodiment, the rigid concrete layer 3 is mixed with slag powder or silica fume, which can effectively improve the durability of the rigid concrete.

[0087] In the example embodiment, the tunnel structure parameter range can include the invert rise-span ratio range, the flexible concrete layer thickness range, the flexible concrete layer fiber mixing amount range, the drainage board layer thickness range, the foam buffer layer thickness range, the waterproof board layer thickness range, the rigid concrete layer thickness range, and the profile steel content rate range.

[0088] Based on the tunnel-based catastrophe risk, the parameter scheme is specifically formulated as follows: Low-risk parameter scheme: 1 / 10≤inverted arch rise-span ratio≤1 / 8 (for example, 1 / 9), applicable to the working condition of sulfate concentration <1000 mg / L and good surrounding rock integrity, to ensure the anti-deformation capacity of the inverted arch under normal load.

[0089] Flexible concrete layer 1: C30 high ductility fiber concrete, 20 cm≤thickness≤25 cm, 0.8%≤fiber content≤1.0% (such as polypropylene fiber), to meet the anti-cracking requirements in a slightly eroded environment.

[0090] Energy dissipation layer 2: outer layer 3 cm thick drainage board layer + middle layer 2 cm thick polyethylene foam board buffer layer + inner layer 1.5 mm thick high-density polyethylene waterproof board layer, in the extension direction of the tunnel, adjacent drainage branch pipes 6 are spaced 5 m apart, with a permeability coefficient ≤1×10 - ³ cm / s, to achieve limited drainage while isolating the sulfate solution.

[0091] Rigid concrete layer 3: secondary lining using C35 concrete, 45 cm≤thickness≤50 cm, with I16 I-shaped steel embedded, in the extension direction of the tunnel, the spacing between adjacent steel sections is 1.2 m, with a steel content of 1.5%≤steel content≤2.0%, to meet the basic bearing requirements.

[0092] Medium-risk parameter scheme: 1 / 8≤inverted arch rise-span ratio≤1 / 6 (for example, 1 / 7), applicable to the working condition of 1000 mg / L≤sulfate concentration≤8000 mg / L and joint development in surrounding rock, to enhance the inverted arch's resistance to osmotic pressure.

[0093] Flexible concrete layer 1: C30 high ductility concrete, 25 cm≤thickness≤30 cm, 1.0%≤fiber content≤1.2% (such as steel fiber and polypropylene fiber hybrid), to improve the anti-erosion and ductility performance.

[0094] Energy dissipation layer 2: outer layer 5 cm thick drainage board layer + middle layer 5 cm thick polyurethane foam board buffer layer + inner layer 1.5 mm thick high-density polyethylene waterproof board layer, in the extension direction of the tunnel, adjacent drainage branch pipes 6 are spaced 3 m apart, with a permeability coefficient ≤1×10 -4 cm / s, to achieve "water isolation as the main function and drainage as the auxiliary function".

[0095] Rigid concrete layer 3: secondary lining using C40 concrete, 50 cm≤thickness≤55 cm, with I20a I-shaped steel embedded, in the extension direction of the tunnel, the spacing between adjacent steel sections is 1.0 m, with a steel content of 2.0%≤steel content≤2.5%, and 5%-8% (including 5% and 8% boundary values) of silica fume is added to improve the impermeability.

[0096] High-risk parameter scheme: 1 / 6≤invert span ratio≤1 / 5 (e.g. take 1 / 5.5), applicable to the working conditions of sulfate concentration > 8000 mg / L, broken surrounding rock and high water pressure, improve the structural stiffness by large span ratio.

[0097] Flexible concrete layer 1: C35 high ductility concrete, 30 cm≤thickness≤35 cm, 1.2%≤fiber content≤1.5% (mainly steel fiber), combined with shotcrete process to ensure the crack resistance and erosion resistance of flexible concrete layer 1.

[0098] Energy dissipation layer 2: outer 5 cm thick drainage plate layer + middle 10 cm thick foam concrete buffer layer + inner 1.5 mm thick high-density polyethylene waterproof plate layer, in the extension direction of the tunnel, the spacing between adjacent drainage branch pipes 6 is 2 m, the permeability coefficient is ≤1×10 -5 cm / s, realizing full sealing and emergency drainage.

[0099] Rigid concrete layer 3: secondary lining adopts C45 high-performance concrete, 55 cm≤thickness≤60 cm, with I22b I-shaped steel inside, in the extension direction of the tunnel, the spacing between adjacent steel sections is 0.8 m, 2.5%≤steel content of steel sections≤3.0%, coated with an epoxy resin coating, and 10%-15% (including 10% and 15% boundary values) of slag powder and sulfate-resistant admixtures are added to the concrete to improve the durability of rigid concrete layer 3.

[0100] Among them, in the case of low risk and medium risk, the structure layer adopts a half package scheme, as shown in Figure 3 , in the case of high risk, the structure layer adopts a full package scheme, as shown in ​ .

[0101] It should be noted that the invert span ratio needs to be determined by considering factors such as the stress state of the tunnel surrounding rock and the influence of sulfate erosion, to ensure that the invert can effectively bear the load and improve the overall stability of the tunnel structure.

[0102] In the example embodiment, the tunnel safety index can include a tunnel structure stiffness reflection index and a tunnel structure durability reflection index, and the tunnel safety index range can include a tunnel structure stiffness index range and a tunnel structure durability index range; step S600 can specifically include the following steps: S610, compare the tunnel structure stiffness reflection index with the tunnel structure stiffness index range; S620, compare the tunnel structure durability reflection index with the tunnel structure durability index range; S630, if the tunnel structure stiffness reflection index is in the tunnel structure stiffness index range and the tunnel structure durability reflection index is in the tunnel structure durability index range, determine the tunnel structure parameters; S640, if the tunnel structure stiffness reflection index is out of the tunnel structure stiffness index range, or the tunnel structure durability reflection index is out of the tunnel structure durability index range, adjust the tunnel structure parameters in the tunnel structure parameter range, so that the tunnel structure stiffness reflection index is in the tunnel structure stiffness index range and the tunnel structure durability reflection index is in the tunnel structure durability index range.

[0103] Specifically, it should be understood that the tunnel structure parameters have three parameter schemes of low risk, medium risk and high risk, and accordingly, the tunnel safety index range has three range schemes corresponding to the three schemes of the tunnel structure parameters.

[0104] When the tunnel structure stiffness reflection index is in the tunnel structure stiffness index range and the tunnel structure durability reflection index is in the tunnel structure durability index range, it can be determined that the tunnel structure parameters meet the engineering requirements, so that the tunnel structure parameter value can be determined.

[0105] When the tunnel structure stiffness reflection index is out of the tunnel structure stiffness index range, or the tunnel structure durability reflection index is out of the tunnel structure durability index range, the tunnel structure parameters need to be adjusted until the tunnel structure stiffness reflection index is in the tunnel structure stiffness index range and the tunnel structure durability reflection index is in the tunnel structure durability index range.

[0106] Among them, 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 under 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.

[0107] In an exemplary embodiment, the tunnel structure stiffness reflection index can include arch crown settlement, side wall displacement, and structure stress concentration coefficient, and the tunnel structure stiffness index range can include arch crown settlement range, side wall displacement range, and structure stress concentration coefficient range; wherein only when the arch crown settlement, side wall displacement, and structure stress concentration coefficient are all in the corresponding range, the tunnel structure stiffness reflection index is in the tunnel structure stiffness index range.

[0108] It should be noted that the tunnel structure stiffness reflection index can be determined by calculating the deformation and stress distribution of the tunnel structure.

[0109] Specifically, the rigidity reflection index calculation can be performed by establishing a tunnel structure model through finite element software (such as ANSYS software), and calculating the vault subsidence, side wall displacement, and stress concentration coefficient under different schemes.

[0110] For example, the high-risk scheme can require that the vault subsidence be less than or equal to 0.3 mm, the side wall displacement be less than or equal to 0.5 mm, and the stress concentration coefficient be less than or equal to 1.8. The requirements for the rigidity reflection index of the specific scheme can be formulated according to the actual situation.

[0111] In an example embodiment, the tunnel structure durability reflection index can include a concrete sulfate attack resistance life, a steel bar corrosion critical time, and a structure crack propagation rate, and the tunnel structure durability index range can include a concrete sulfate attack resistance life range, a steel bar corrosion critical time range, and a structure crack propagation rate range. Only when the concrete sulfate attack resistance life, the steel bar corrosion critical time, and the structure crack propagation rate are all within the corresponding ranges, the tunnel structure durability index is within the tunnel structure durability index range.

[0112] The tunnel structure durability reflection index can be determined by calculating parameters such as the sulfate attack resistance of the concrete and the corrosion rate of the steel bar.

[0113] Specifically, the durability reflection index calculation can use the Nernst equation combined with accelerated corrosion tests to calculate the concrete sulfate attack resistance life, the steel bar corrosion critical time, and the structure crack propagation rate.

[0114] For example, under three different risk tunnel structure parameter schemes, the concrete sulfate attack resistance life can be required to be greater than or equal to 100 years, the steel bar corrosion critical time can be required to be greater than or equal to 80 years, and the structure crack propagation rate can be required to be less than or equal to 0.02 mm / year. Here, the concrete includes the flexible concrete layer 1 and the rigid concrete layer 3.

[0115] For example, if part of the parameter values in the rigidity index of the high-risk scheme exceed 10% of the specification limit or part of the parameter values in the durability index are lower than 20% of the design standard, the parameters can be adjusted (such as increasing the inverted arch rise-span ratio or increasing the steel ratio), and the calculation can be performed again until the requirements are met.

[0116] In the above scheme, through multi-scale verification of finite element analysis and accelerated corrosion tests, the long-term reliability of the design parameter scheme is ensured, and the technical gap in the multi-index coordinated verification of tunnel structures in a complex dissolution and erosion environment is filled.

[0117] The above is only a preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the present application.

Claims

1. A method of designing anti-erosion tunnel parameters, characterized by, The method comprises: acquiring tunnel environment information and a tunnel safety index range; determining a tunnel disaster risk based on the tunnel environment information; determining a tunnel structure parameter range based on the tunnel disaster risk; determining a tunnel structure parameter based on the tunnel structure parameter range; determining a tunnel safety index based on the tunnel structure parameter; determining whether to adjust the tunnel structure parameter based on a comparison result of the tunnel safety index and the tunnel safety index range.

2. The method of designing an erosion-resistant tunnel parameter of claim 1, wherein, The tunnel environment information comprises a sulfate concentration, a surrounding rock permeability coefficient, and a surrounding rock stress intensity ratio; The determination of the tunnel disaster risk based on the tunnel environment information comprises: acquiring a sulfate concentration threshold, a surrounding rock permeability coefficient threshold, and a surrounding rock stress intensity ratio threshold; determining a sulfate concentration grade based on a comparison result of the sulfate concentration and the sulfate concentration threshold; determining a surrounding rock permeability coefficient grade based on a comparison result of the surrounding rock permeability coefficient and the surrounding rock permeability coefficient threshold; determining a surrounding rock stress intensity ratio grade based on a comparison result of the surrounding rock stress intensity ratio and the surrounding rock stress intensity ratio threshold; determining the tunnel disaster risk based on the sulfate concentration grade, the surrounding rock permeability coefficient grade, and the surrounding rock stress intensity ratio grade; The sulfate concentration grade, the surrounding rock permeability coefficient grade, and the surrounding rock stress intensity ratio grade are all divided into three levels according to the degree of harm, with the third level being the highest.

3. The method of designing an erosion-resistant tunnel parameter of claim 2, wherein, The surrounding rock stress intensity ratio is determined based on the following formula: In the formula, represents the stress intensity ratio of the surrounding rock; represents the maximum principal stress borne by the rock mass or rock; represents the uniaxial compressive strength of the rock.

4. The method of designing an erosion-resistant tunnel parameter of claim 2, wherein, The determination of the tunnel disaster risk based on the sulfate concentration grade, the surrounding rock permeability coefficient grade, and the surrounding rock stress intensity ratio grade comprises: determining a highest harm grade based on the sulfate concentration grade, the surrounding rock permeability coefficient grade, and the surrounding rock stress intensity ratio grade, wherein the highest harm grade is the grade with the highest degree of harm among the sulfate concentration grade, the surrounding rock permeability coefficient grade, and the surrounding rock stress intensity ratio grade; if the highest harm grade is the first level, the tunnel disaster risk is low; if the highest harm grade is the second level, and there is only one tunnel environment information in the second level, the tunnel disaster risk is medium; if the highest harm grade is the third level or there are at least two tunnel environment information in the second level, the tunnel disaster risk is high.

5. The method of designing an erosion-resistant tunnel parameter of claim 1, wherein, The tunnel safety index comprises a tunnel structure stiffness reflection index and a tunnel structure durability reflection index, and the tunnel safety index range comprises a tunnel structure stiffness index range and a tunnel structure durability index range; the determination or adjustment of the tunnel structure parameter based on the comparison result of the tunnel safety index and the tunnel safety index range comprises: comparing the tunnel structure stiffness reflection index with the tunnel structure stiffness index range; comparing the tunnel structure durability reflection index with the tunnel structure durability index range; if the tunnel structure stiffness reflection index is within the tunnel structure stiffness index range, and the tunnel structure durability reflection index is within the tunnel structure durability index range, determining the tunnel structure parameter; If the tunnel structure stiffness reflection index is out of the tunnel structure stiffness index range or the tunnel structure durability reflection index is out of the tunnel structure durability index range, the tunnel structure parameters are adjusted in the tunnel structure parameter range so that the tunnel structure stiffness reflection index is in the tunnel structure stiffness index range and the tunnel structure durability reflection index is in the tunnel structure durability index range.

6. The method of designing an erosion-resistant tunnel parameter of claim 5, wherein, The tunnel structure stiffness reflection index includes vault subsidence, side wall displacement, and structure stress concentration coefficient, and the tunnel structure stiffness index range includes vault subsidence range, side wall displacement range, and structure stress concentration coefficient range. Only when the vault subsidence, the side wall displacement, and the structure stress concentration coefficient are in the corresponding ranges, the tunnel structure stiffness reflection index is in the tunnel structure stiffness index range.

7. The method of designing an erosion-resistant tunnel parameter of claim 5, wherein, The tunnel structure durability reflection index includes concrete sulfate attack resistance life, steel corrosion critical time, and structure crack propagation rate, and the tunnel structure durability index range includes concrete sulfate attack resistance life range, steel corrosion critical time range, and structure crack propagation rate range. Only when the concrete sulfate attack resistance life, the steel corrosion critical time, and the structure crack propagation rate are in the corresponding ranges, the tunnel structure durability index is in the tunnel structure durability index range.

8. The method of designing an erosion-resistant tunnel parameter of claim 1, wherein, The tunnel includes a flexible concrete layer (1), an energy dissipation layer (2), and a rigid concrete layer (3) arranged in sequence from outside to inside; the energy dissipation layer (2) includes: a drainage board layer connected with the flexible concrete layer (1); a foam buffer layer arranged on the inner side of the drainage board layer; a waterproof board layer arranged on the inner side of the foam buffer layer and connected with the rigid concrete layer (3).

9. The method of designing an erosion-resistant tunnel parameter of claim 8, wherein, The flexible concrete layer (1) is mixed with fibers, and the rigid concrete layer (3) is provided with profile steel arranged along the circumferential direction of the tunnel, and the profile steel has multiple and is arranged at intervals in the extension direction of the tunnel.

10. The method of designing an erosion-resistant tunnel parameter of claim 9, wherein, The tunnel structure parameter range includes invert span ratio range, flexible concrete layer thickness range, flexible concrete layer fiber mixing amount range, drainage board layer thickness range, foam buffer layer thickness range, waterproof board layer thickness range, rigid concrete layer thickness range, and profile steel content rate range.

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