A tunnel drainage structure and design method based on maintenance cycle

Abstract

The present invention relates to the technical field of tunnel drainage design, and specifically to a tunnel drainage structure and design method based on a maintenance cycle, comprising: obtaining tunnel groundwater environmental parameters; calculating the crystallization deposition rate of groundwater in a tunnel longitudinal drainage pipe; calculating the crystallization deposition amount of the tunnel longitudinal drainage pipe within the maintenance cycle according to the crystallization deposition rate; comparing the crystallization deposition amount of the tunnel longitudinal drainage pipe within the maintenance cycle with the crystallization deposition standard, obtaining the tunnel drainage pipe parameter relationship, and designing the tunnel drainage pipe based on the parameter relationship; the beneficial effect of the present invention is that the method aims to construct a tunnel drainage system design method from the life cycle and maintainability dimensions of the drainage system, thereby enhancing the controllability of crystallization blockage of the tunnel drainage pipe.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel drainage design, and in particular to a tunnel drainage structure and design method based on a maintenance cycle. Background Art

[0002] In the safety control of the whole life cycle of the tunnel, tunnel water leakage is a kind of disease with a wide range and high frequency, which has a great impact on the long-term safety and durability of the tunnel. Among them, the blockage and crystallization of the tunnel drainage system is an important factor that induces the increase of water pressure behind the tunnel lining and the aggravation of water leakage. At the same time, the blockage of the tunnel drainage will cause a large amount of water to accumulate in the tunnel, which seriously threatens the stability of the lining structure and load. At present, the problem of drainage pipe blockage is mostly solved from the direction of pipeline cleaning. Chemical or physical methods are used to remove crystals in the pipeline based on the maintenance cycle. However, during the maintenance cycle, how to make the crystals in the pipeline meet the use requirements of the tunnel drainage structure and realize the maintenance cycle control, there is currently no relevant solution.

[0003] Therefore, developing a tunnel drainage structure and design method based on a maintenance cycle not only has urgent research value, but also has good economic benefits and industrial application potential, which is the driving force and basis for the completion of the present invention. Summary of the invention

[0004] In order to overcome the above-mentioned defects of the prior art, the inventors conducted in-depth research and completed the present invention after paying a lot of creative work.

[0005] Specifically, the technical problem to be solved by the present invention is: to provide a tunnel drainage structure and design method based on the maintenance cycle, by identifying the amount of crystallization of the tunnel drainage pipe and based on the upper limit of crystallization blockage in drainage pipe operation, to determine the design parameters of the tunnel drainage system.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A tunnel waterproofing and drainage design method based on maintenance cycle, comprising:

[0008] Obtain tunnel groundwater environmental parameters;

[0009] Calculate the crystallization sedimentation rate of groundwater in the tunnel longitudinal drainage pipe;

[0010] Calculate the crystal deposition amount of the tunnel longitudinal drainage pipe during the maintenance period according to the crystal deposition rate;

[0011] The crystal deposition amount of the tunnel longitudinal drainage pipe during the maintenance period is compared with the crystal deposition standard to obtain the parameter relationship between the tunnel longitudinal drainage pipe and the annular drainage pipe, and the tunnel drainage pipe is designed based on the parameter relationship;

[0012] The tunnel groundwater environmental parameters obtained include groundwater composition, ambient temperature, groundwater static water head elevation in the tunnel site, and HCO3 in groundwater. - , Ca 2+ (bicarbonate, calcium ion) activity.

[0013] In the present invention, as an improvement, the calculation of the crystallization deposition rate of groundwater in the tunnel drainage pipe includes:

[0014] Calculate the water seepage of surrounding rock in a unit interval of a tunnel with waterproof structure under design conditions, and calculate the flow rate of tunnel drainage pipe in unit time based on the water seepage of surrounding rock in a unit interval;

[0015] Calculate the water flow cross section in the pipe based on the flow rate of the tunnel drainage pipe per unit time;

[0016] The crystallization deposition rate of groundwater in the tunnel longitudinal drainage pipe is calculated based on the water flow section in the pipe, groundwater environmental parameters and groundwater crystallization material coefficient.

[0017] In the present invention, as an improvement, the water seepage of the surrounding rock of the tunnel in a unit interval with a waterproof structure under design conditions is calculated as follows:

[0018] (1) Construct design conditions that meet the groundwater environment;

[0019] (2) Taking the area between two adjacent annular drainage pipes as the unit interval, the functional relationship between the surrounding rock seepage and the influencing factors in the unit interval is obtained;

[0020] (3) Construct the water pressure boundary conditions of the unit interval tunnel;

[0021] (4) Calculate the total water seepage of the surrounding rock of the tunnel in a unit interval with a waterproof structure based on boundary conditions;

[0022] The tunnel water pressure boundary conditions within the unit interval are as follows: the inner and outer boundaries of the initial support of the tunnel are both equal head boundaries, and the water pressure inside the initial support changes linearly along the longitudinal direction.

[0023] In the present invention, as an improvement, the design conditions that meet the groundwater environment include:

[0024] 1) The groundwater in the surrounding rock of the tunnel site is under hydrostatic pressure;

[0025] 2) The groundwater seepage state is steady-state seepage, satisfying Darcy's law;

[0026] 3) Groundwater infiltrates through the three-layer structure of surrounding rock, initial support and geotextile in sequence, and is discharged to the longitudinal drainage pipe through the annular drainage pipe. The water pressure in the annular drainage pipe is constant at 0 kPa.

[0027] In the present invention, as an improvement, the functional relationship between the water seepage of surrounding rock in a unit interval and the influencing factors is as follows:

[0028] Q=f(h,r1,r2,k r ,k z ,k l ,D,t)

[0029] Among them, r1 is the tunnel radius, r2 is the initial support outer radius, k r is the permeability coefficient of the tunnel surrounding rock, k l is the initial support permeability coefficient, k z is the geotextile permeability coefficient, h is the vertical distance between the tunnel center and the groundwater level, D is the spacing between the annular drainage pipes, and t is the tunnel seepage time;

[0030] Based on the water pressure boundary condition, the water seepage of the tunnel surrounding rock in a unit interval with waterproof structure is:

[0031]

[0032] Where: surrounding rock permeability coefficient k r , initial support permeability coefficient k l , Geotextile Permeability Coefficient k z .

[0033] In the present invention, as an improvement, the flow rate of the tunnel drainage pipe per unit time is:

[0034]

[0035] Among them, L is the horizontal drainage pipe spacing, and D is the annular drainage pipe spacing;

[0036] The water flow cross section in the pipe is calculated as follows:

[0037]

[0038] Among them, S is the surface area of ​​the water pipe; Q0 is the flow rate of the longitudinal drainage pipe per unit time; v is the flow velocity; r p is the pipe radius: h p is the height of water flow in the longitudinal pipe; L is the horizontal drainage pipe spacing.

[0039] In the present invention, as an improvement, the crystallization deposition rate of groundwater in the tunnel drainage pipe is:

[0040] R=K(f(θ),S,A1,A2,T)

[0041] In the formula, A1 and A2 are Ca 2+ activity, T is the temperature.

[0042] In the present invention, as an improvement, the crystal deposition amount of the tunnel drainage pipe during the maintenance period is calculated according to the crystal deposition rate using the following formula:

[0043] m(t)=M r ·R·c·t

[0044] Among them, M r is the relative molecular mass of the crystal, c is the dimensionless coefficient, and R is the crystal deposition rate in the tunnel drainage pipe.

[0045] In the present invention, as an improvement, the crystal deposition standard is the maximum crystal deposition amount allowed for the operation of the tunnel drainage pipe during the maintenance period, which is defined according to the tunnel drainage pipe parameters, wherein the crystal deposition standard per unit length of the drainage pipe is as follows:

[0046]

[0047] Where, ρ is the crystal density of calcium carbonate;

[0048] Tunnel drainage pipe dredging cycle T s Internal crystallization amount m(T s )satisfy:

[0049]

[0050] Based on the relationship between the crystal deposition amount of tunnel drainage pipes and the deposition standard during the maintenance period, the parameter relationship between the tunnel transverse drainage pipe spacing, the annular drainage pipe spacing and the longitudinal drainage pipe radius is obtained by composite calculation.

[0051] A tunnel drainage structure based on a maintenance cycle, comprising a longitudinal drainage pipe and an annular drainage pipe arranged in the tunnel structure, wherein the annular drainage pipes are arranged at equal intervals along the depth direction of the tunnel, the spacing between two adjacent annular drainage pipes is D, and both ends of the annular drainage pipe are connected to the longitudinal drainage pipes on both sides thereof;

[0052] The tunnel structure is arranged in the surrounding rock, including an outer initial support and an inner geotextile, and the annular drainage pipe is arranged inside the geotextile.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) This method aims to construct a tunnel drainage system design method from the dimensions of drainage system life cycle and maintainability, thereby enhancing the controllability of crystallization blockage in tunnel drainage pipes.

[0055] (2) The present invention determines the tunnel drainage volume and drainage crystallization generation by predicting the groundwater drainage volume around the tunnel and identifying the surrounding environment; and then determines the maximum crystallization upper limit of the drainage pipe to ensure the safe flow of the drainage system based on the drainage pipe flushing cycle, thereby determining the design parameters of the tunnel drainage system to ensure smooth groundwater drainage during operation.

[0056] (3) This application constructs the relationship between the crystallization of the drainage pipe during the maintenance period and the design parameters through calculation, adjusts the tunnel drainage design on the premise of meeting the tunnel drainage pipe crystallization standards, avoids the blockage of the drainage pipe during the maintenance period due to crystallization, and provides a basis for the design of the maintenance period. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0058] Figure 1 A schematic diagram of the design method of the present invention;

[0059] Figure 2 It is a schematic diagram of the linear change of water pressure in the longitudinal direction of the initial support of the present invention;

[0060] Figure 3 This is a schematic diagram of the drainage pipe arrangement in the tunnel of the present invention;

[0061] Figure 4 It is a schematic diagram of various parameters in the tunnel of the present invention;

[0062] Figure 5 It is a schematic diagram of the cross section of water flow in the pipeline of the present invention. DETAILED DESCRIPTION

[0063] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0064] A tunnel drainage structure based on a maintenance cycle, comprising a transverse drainage pipe, a longitudinal drainage pipe and an annular drainage pipe arranged in the tunnel structure, wherein the annular drainage pipes are arranged at equal intervals along the depth direction of the tunnel, and the spacing between two adjacent annular drainage pipes is D;

[0065] The tunnel structure is set in the surrounding rock, including the outer primary support and the inner geotextile. The annular drainage pipe is set on the inner side of the geotextile. The rock seepage water outside the surrounding rock tunnel structure penetrates into the primary support and the geotextile in sequence.

[0066] Tunnel drainage design method based on maintenance cycle, such as Figure 1 As shown, including:

[0067] (1) Investigate the tunnel groundwater environment and obtain the tunnel groundwater environmental parameters, including groundwater composition, ambient temperature, static water head elevation of the tunnel site, and groundwater Ca 2+ The above environmental parameters affect the crystallization characteristics of groundwater.

[0068] (2) constructing design conditions that meet the groundwater environment, and calculating the water seepage of the surrounding rock of a tunnel with a waterproof structure within a unit interval based on the design conditions, wherein the design conditions include:

[0069] The groundwater in the tunnel surrounding rock is under hydrostatic pressure and remains stable, with a head height of h;

[0070] The groundwater seepage state is steady-state seepage, satisfying Darcy's law;

[0071] Groundwater infiltrates through the three-layer structure of surrounding rock, initial support and geotextile in sequence, and is discharged to the longitudinal drainage pipe through the annular drainage pipe. The water pressure in the annular drainage pipe is constant at 0kPa, and the distance between two adjacent annular drainage pipes is D;

[0072] The inner and outer boundaries of the initial support of the tunnel are both equal water head boundaries, among which the total water head of the outer boundary is h r1 ; The water pressure in the initial support is p(z) which changes linearly along the longitudinal direction, such as Figure 2 shown.

[0073] like Figure 3 As shown in the figure, the area between two adjacent annular drainage pipes is taken as the unit interval. The surrounding rock seepage in the unit interval flows from the annular drainage pipe into the longitudinal drainage pipe in the interval section and is deposited in the longitudinal drainage pipe. The function of the tunnel surrounding rock seepage in the unit interval and the influencing factors is as follows:

[0074] Q=f(h,,r1,r2,k r ,k z ,k l ,D,t)

[0075] Among them, r1 is the tunnel radius, r2 is the initial support outer radius, k r is the permeability coefficient of the tunnel surrounding rock, k l is the initial support permeability coefficient, k z is the geotextile permeability coefficient, h is the vertical distance between the tunnel center and the groundwater level, D is the spacing between the annular drainage pipes, and t is the tunnel seepage time.

[0076] After considering the water pressure boundary conditions, Figure 4As shown in the figure, the calculation formula for the tunnel surrounding rock water seepage in a unit interval is as follows:

[0077]

[0078] Where: surrounding rock permeability coefficient k r , initial support permeability coefficient k l , Geotextile Permeability Coefficient k z ;

[0079] The constant α is calculated as follows:

[0080]

[0081] (3) Calculate the tunnel drainage pipe flow rate Q0 per unit time based on the surrounding rock seepage Q:

[0082]

[0083] Wherein, L is the horizontal drainage pipe spacing, and D is the annular drainage pipe spacing.

[0084] (4) Calculate the water flow cross section in the pipe based on the flow rate of the tunnel drainage pipe per unit time;

[0085] The cross section of the water flow in the pipe is Figure 5 As shown, the specific calculation formula is as follows:

[0086]

[0087] Among them, S is the surface area of ​​the water pipe; Q0 is the flow rate of the longitudinal drainage pipe per unit time; v is the flow velocity; r p is the pipe radius; h p is the height of water flow in the longitudinal pipe; L is the horizontal drainage pipe spacing.

[0088] (5) The crystallization and deposition rate of groundwater in the tunnel drainage pipe is related to the water flow cross section in the pipe, the groundwater environmental parameters, and the contact angle function between water and the pipe surface. The pipe material determines the contact angle θ between groundwater and the inner surface of the pipe. The groundwater crystallization material coefficient is f(θ). The groundwater deposition rate R is:

[0089] R=K(f(θ),S,A1,A2,T)

[0090] In the formula, A1 and A2 are Ca 2+ activity, T is the temperature.

[0091] The groundwater crystal material coefficient f(θ) is:

[0092] f(θ)=4.08×10 7 ·θ -3.64

[0093] Then, the groundwater sedimentation velocity input coefficient and velocity constant are calculated as follows:

[0094] R=f(θ)·S·[K1-K2·A1·A2·K s 10 pH 10 -12 ]

[0095] K1 is the rate constant, mol / (s·cm 2 ); K2 is the rate constant, cm 4 / (s·mol).

[0096] K1=(0.07623T-0.201)×10 -11

[0097] K2=106.7T-466.67

[0098]

[0099] (6) The crystal deposition amount of the tunnel drainage pipe during the maintenance period is calculated based on the crystal deposition rate using the following formula:

[0100] m(t)=M r ·R·c·t

[0101] Among them, M r is the relative molecular mass of the crystal, c is the dimensionless coefficient, c = 8.64 × 10 4 , R is the crystal deposition rate in the tunnel drainage pipe.

[0102] According to the tunnel drainage design standard, the crystal deposition standard in the tunnel drainage pipe is: the crystal section height in the pipe is less than 1 / 2 of the drainage pipe radius. Therefore, the crystal quality per unit length of the drainage pipe is as follows:

[0103]

[0104] Where, ρ is the crystal density of calcium carbonate;

[0105] Tunnel drainage pipe dredging cycle T s Internal crystallization amount m(T s )satisfy:

[0106]

[0107] (7) Based on the relationship between the crystal deposition amount of tunnel drainage pipes during the maintenance period and the deposition standard, the parameter relationship between the tunnel transverse drainage pipe spacing, the annular drainage pipe spacing and the longitudinal drainage pipe radius is obtained through composite calculation;

[0108] From the above calculation, we can know that the height h of water flow in the longitudinal drainage pipe is p Not greater than 2 / 3 of the pipe radius, thus the maximum parameter of the longitudinal drainage pipe radius is obtained.

[0109] Based on the crystallization amount m(T s ) and the standard sedimentation formula, substitute the formulas in the previous steps into the calculation to obtain the parameters of the tunnel transverse drainage pipe spacing and the annular drainage pipe spacing, and obtain the tunnel drainage pipe parameter relationship.

[0110] Embodiment 1:

[0111] During the engineering survey and design stage of a tunnel, the groundwater environment of the tunnel was investigated and the following results were obtained:

[0112] 1) The annual ambient temperature T of the rock mass at the depth of the tunnel is 10°C and the pH value is 9;

[0113] 2) The chemical composition of groundwater is mainly HCO 3- 、Na + , K + , Ca 2+ ,Mg 2+ etc., among which Ca 2+ The activities were 3.4mmol / L and 2.06mmol / L respectively;

[0114] 3) Investigate and estimate the long-term static water head elevation of groundwater in the tunnel site area, h, to be 15m;

[0115] 4) The permeability coefficient of the tunnel surrounding rock is 8×10 -5 m / s; there is a risk of groundwater crystallization in the tunnel.

[0116] The tunnel is designed to be initially supported by C25 shotcrete lining, with a permeability coefficient of about 4×10 -5 m / s, the inner diameter of the initial support lining (tunnel radius) is 12m, and the outer diameter is 12.4m; geotextile is laid between the waterproof board and the initial support, and its permeability coefficient is 6×10 -5 m / s, the tunnel longitudinal drainage pipe uses a HDPE pipe with a diameter of 11 cm, the contact angle θ is 88.8°, the slope of the longitudinal drainage pipe is consistent with the designed slope of 2% of the route, the water flow rate in the water pipe is 0.91m / s, and the water flow height in the longitudinal pipe is 2 / 3 of the pipe radius; after the tunnel is completed and put into operation, the drainage system is cleaned once every 3 years.

[0117] (1) Calculation of water seepage in surrounding rock of tunnel with waterproof structure

[0118] The tunnel radius r1, initial support outer diameter r2, k r Tunnel surrounding rock permeability coefficient k r, initial support permeability coefficient k l , k z Geotextile permeability coefficient k z , the vertical distance h between the tunnel center and the groundwater level is substituted into:

[0119]

[0120] in,

[0121] It turns out that:

[0122]

[0123] (2) Calculation of water flow cross section in pipes

[0124] The tunnel longitudinal drainage pipe adopts HDPE pipe with a radius of 0.055m. The contact angle θ of this type of pipe is 88.8°. The slope of the longitudinal drainage pipe is consistent with the designed slope of the route of 2%. The water flow velocity in the water pipe is 0.91m / s. The water flow height h in the longitudinal pipe is 0.055m. p The maximum value is 2 / 3 of the pipe radius; then:

[0125]

[0126] Among them, Q0 is the flow rate of the longitudinal drainage pipe within the range of L per unit time at t=1:

[0127]

[0128] We can get:

[0129]

[0130] (3) Calculation of groundwater sedimentation rate

[0131] The contact angle θ of the HDPE pipe is 88.8°, and the groundwater crystallization material coefficient f(θ) can be obtained:

[0132] f(θ)=4.08×10 8 ·θ -3.64 =4.08×10 7 88.8 -3.64 =32.9

[0133] And since A1 and A2 are 3.4mmol / L and 2.06mmol / L respectively, and the temperature T is 10℃, we can get:

[0134] K1=(0.07623T-0.201)×10 -11 =5.613×10 -12

[0135] K2=106.7T-466.67=600.33

[0136]

[0137] Then, the groundwater precipitation rate is calculated as follows:

[0138] R=f(θ)·S·[K1-K2·A1·A2·K s 10 pH 10 -12 ]=4.3*10 -9 S

[0139] (4) Quality of crystals in groundwater drainage pipes

[0140] The relative molecular mass of the crystal is 100 g / mol; c is the dimensionless coefficient, c = 8.64 × 10 4 , the crystal quality of the drainage pipe dredging cycle in operation for 3 years:

[0141] m(t)=M r R c t = 100 * 8.64 × 10 4 *3*365*4.3*10 -9 St

[0142] m(t)=40.68S

[0143] (5) Allowable value of crystals in groundwater drainage pipes M

[0144] The depth of the crystallization section of the tunnel longitudinal drainage pipe shall not exceed 1 / 2 of the radius of the longitudinal drainage pipe, which is obtained from the crystallization mass per unit length:

[0145]

[0146] The crystal quality of tunnel drainage pipes should meet the following relationship during the dredging cycle:

[0147] m(T s ) <M

[0148] Right now:

[0149]

[0150] (6) Determine the relationship between the tunnel annular drainage pipe spacing D and the transverse drainage pipe spacing L

[0151] According to the tunnel drainage design standard, the design parameters of the tunnel annular drainage pipe spacing D and the transverse drainage pipe spacing L that meet the requirements of the above formula are shown in the table:

[0152] Serial number D / m L / m 1 1 4.15 2 2 8.74 3 3 14.23 4 4 21.06 5 5 29.63 6 6 40.29 7 10 108.58

[0153] Based on tunnel parameters, drainage pipe drainage reliability and construction convenience, the tunnel annular drainage pipe spacing is designed to be 5m, and the transverse drainage pipe spacing L is less than 29.63m. Based on tunnel construction standards, the transverse drainage pipe spacing is designed to be 20m. Substitute:

[0154]

[0155] Calculated by the above formula, it is concluded that the selected tunnel drainage pipe parameters meet the tunnel drainage crystallization design requirements.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A tunnel drainage design method based on maintenance cycle, characterized in that: include: Obtain tunnel groundwater environmental parameters; Calculate the crystallization sedimentation rate of groundwater in the tunnel longitudinal drainage pipe; Calculate the crystal deposition amount of the tunnel longitudinal drainage pipe during the maintenance period according to the crystal deposition rate; The crystal deposition amount of the tunnel longitudinal drainage pipe during the maintenance period is compared with the crystal deposition standard to obtain the parameter relationship between the tunnel longitudinal drainage pipe and the annular drainage pipe, and the tunnel drainage pipe is designed based on the parameter relationship; The tunnel groundwater environmental parameters obtained include groundwater composition, ambient temperature, groundwater static water head elevation in the tunnel site, and HCO3 in groundwater. - , Ca 2+ (bicarbonate, calcium ion) activity; Calculation of groundwater crystallization deposition rate in tunnel drainage pipes includes: Calculate the water seepage of surrounding rock in a unit interval of a tunnel with waterproof structure under design conditions, and calculate the flow rate of tunnel drainage pipe in unit time based on the water seepage of surrounding rock in a unit interval; Calculate the water flow cross section in the pipe based on the flow rate of the tunnel drainage pipe per unit time; The crystallization deposition rate of groundwater in the tunnel longitudinal drainage pipe is calculated based on the water flow section in the pipe, groundwater environmental parameters and groundwater crystallization material coefficient.

2. The tunnel waterproofing and drainage design method based on maintenance cycle according to claim 1 is characterized in that: The water seepage of surrounding rock in a unit section of a tunnel with waterproof structure under design conditions is calculated as follows: (1) Construct design conditions that meet the groundwater environment; (2) Taking the area between two adjacent annular drainage pipes as the unit interval, the functional relationship between the surrounding rock seepage and the influencing factors in the unit interval is obtained; (3) Construct the water pressure boundary conditions of the unit interval tunnel; (4) Calculate the total water seepage of the surrounding rock of the tunnel in a unit interval with a waterproof structure based on boundary conditions; The tunnel water pressure boundary conditions within the unit interval are as follows: the inner and outer boundaries of the initial support of the tunnel are both equal head boundaries, and the water pressure inside the initial support changes linearly along the longitudinal direction.

3. The tunnel waterproofing and drainage design method based on maintenance cycle according to claim 2 is characterized in that: Design conditions for building a groundwater environment include: 1) The groundwater in the surrounding rock of the tunnel site is under hydrostatic pressure; 2) The groundwater seepage state is steady-state seepage, satisfying Darcy's law; 3) Groundwater infiltrates through the three-layer structure of surrounding rock, initial support and geotextile in sequence, and is discharged to the longitudinal drainage pipe through the annular drainage pipe. The water pressure in the annular drainage pipe is constant at 0 kPa.

4. The tunnel waterproofing and drainage design method based on maintenance cycle according to claim 1 is characterized in that: The functional relationship between the surrounding rock seepage and influencing factors in a unit interval is as follows: Q=f(h,r1,r2,k r ,k z ,k l ,D,t) Among them, r1 is the radius of the tunnel, r2 is the outer radius of the initial support, h is the vertical distance from the center of the tunnel to the groundwater level, D is the spacing of the annular drainage pipes, and t is the tunnel seepage time; Based on the water pressure boundary condition, the water seepage of the tunnel surrounding rock in a unit interval with waterproof structure is: Where: surrounding rock permeability coefficient k r , initial support permeability coefficient k l , Geotextile Permeability Coefficient k z , α is a constant.

5. The tunnel waterproofing and drainage design method based on maintenance cycle according to claim 1 is characterized in that: The flow rate of the tunnel drainage pipe per unit time is: Among them, r1 is the tunnel radius, r2 is the initial support outer radius, k r is the permeability coefficient of the tunnel surrounding rock, k l is the initial support permeability coefficient, k z is the geotextile permeability coefficient, h is the vertical distance from the tunnel center to the groundwater level, L is the spacing between the lateral drainage pipes, D is the spacing between the annular drainage pipes, and t is the tunnel seepage duration; The water flow cross section in the pipe is calculated as follows: Among them, S is the surface area of ​​the water pipe; Q0 is the flow rate of the longitudinal drainage pipe per unit time; v is the flow velocity; r p is the pipe radius: h p It is the height of water flow in the longitudinal pipe.

6. The tunnel waterproofing and drainage design method based on maintenance cycle according to claim 1 is characterized in that: The crystallization deposition rate of groundwater in the tunnel drainage pipe is: R=K(f(θ),S,A1,A2,T) In the formula, A1 and A2 are Ca 2+ activity, T is the temperature, S is the surface area in the water pipe, and f(θ) is the groundwater crystal material coefficient.

7. The tunnel waterproofing and drainage design method based on maintenance cycle according to claim 1 is characterized in that: The following formula is used to calculate the crystal deposition amount of the tunnel drainage pipe during the maintenance period based on the crystal deposition rate: m(t)=M r ·R·c·t Among them, M r is the relative molecular mass of the crystal, c is the dimensionless coefficient, R is the crystal deposition rate in the tunnel drainage pipe, and t is the tunnel seepage time.

8. The tunnel waterproofing and drainage design method based on maintenance cycle according to claim 1 is characterized by: The crystal deposition standard is the maximum crystal deposition amount allowed for the operation of the tunnel drainage pipe during the maintenance period, which is defined according to the tunnel drainage pipe parameters. The crystal deposition standard per unit length of drainage pipe is as follows: Where ρ is the crystal density of calcium carbonate, r p is the pipe radius; Tunnel drainage pipe dredging cycle T s Internal crystallization amount m(T s )satisfy: Based on the relationship between the crystal deposition amount of tunnel drainage pipes and the deposition standard during the maintenance period, the parameter relationship between the tunnel transverse drainage pipe spacing, the annular drainage pipe spacing and the longitudinal drainage pipe radius is obtained by composite calculation.

9. A tunnel waterproofing and drainage structure using the design method of claim 1, characterized in that: It includes longitudinal drainage pipes and annular drainage pipes arranged in the tunnel structure, wherein the annular drainage pipes are arranged at equal intervals along the depth direction of the tunnel, the spacing between two adjacent annular drainage pipes is D, and both ends of the annular drainage pipes are connected to the longitudinal drainage pipes on both sides thereof; The tunnel structure is arranged in the surrounding rock, including an outer initial support and an inner geotextile, and the annular drainage pipe is arranged inside the geotextile.

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