Combined lining water conveyance tunnel external water internal seepage control method and system

Abstract

The application discloses a kind of combined lining water conveyance tunnel's outer water internal infiltration control method and system, including disclose a kind of combined lining water conveyance tunnel outer water internal infiltration control method based on the ratio (d / E) of composite drain board thickness d and elastic modulus E.The method is by establishing the stress numerical calculation model of combined lining structure, obtains the opening amount of outer lining segment joint under different d / E scheme;Further establish the seepage field numerical calculation model, calculate the internal infiltration amount of tunnel outer water, and verify that it is less than the drainage capacity of composite drain board;Finally, using curve fitting method, determine the d / E value range of composite drain board that meets the control standard of outer water internal infiltration amount.The application solves the problem that parameter determination method is single and lacks system verification in the prior art, can effectively control the internal infiltration amount of water conveyance tunnel, ensure that the influence of tunnel operation on groundwater environment is within controllable range, can be applied to combined lining high-pressure water conveyance tunnel engineering under complex hydrogeological conditions in urban area.

Description

Technical Field

[0001] This invention relates to the field of seepage control technology for hydraulic structures, specifically to a method and system for controlling external water seepage in a combined-lined water conveyance tunnel, particularly a method and system for controlling external water seepage in a combined-lined water conveyance tunnel based on the ratio (d / E) of the composite drainage board thickness d to the elastic modulus E. Background Technology

[0002] Numerous water conveyance tunnels traverse urban built-up areas, regions with complex hydrogeological conditions, high groundwater pressure, and sensitive environments, placing stringent demands on the tunnel structures' seepage prevention performance, deformation control capabilities, and durability. Traditional single-layer segment lining structures have limited inherent rigidity and insufficient seepage resistance, making them unsuitable for the high-pressure, complex geological conditions of urban water conveyance tunnels. They cannot simultaneously meet the multiple requirements of structural safety operation, seepage prevention and water control, and protection of surrounding groundwater, thus exhibiting significant limitations in application.

[0003] To overcome the technical shortcomings of single-layer segment lining, existing technologies have proposed a composite lining structure. This structure mainly consists of an outer segment lining, an intermediate self-compacting concrete filling layer, and an inner steel lining, and is currently the mainstream structural form for high-pressure water conveyance tunnels. The steel lining can block the exchange of water between the inside and outside of the tunnel, preventing groundwater contamination of the conveyed water. A composite drainage board cushion layer is installed between the segment lining and the self-compacting concrete layer, achieving flexible separation between the inner and outer structures, optimizing the stress state of the steel lining, improving its internal water pressure bearing capacity, and simultaneously draining seepage water from the structure. The intermediate self-compacting concrete filling can solidify the overall structure, significantly improving the steel lining's resistance to external pressure and effectively adapting to high-pressure water conveyance operating conditions.

[0004] The aforementioned composite lining structure still has inherent technical defects. During tunnel operation with water filling, the high internal water pressure will drive the steel lining to undergo radial outward expansion deformation. This deformation load is transferred layer by layer to the external tunnel lining segments through the self-compacting concrete layer and the composite drainage board, causing the joints of the tunnel lining segments to open and shift. Because the steel lining has completely waterproof properties, it can prevent internal water from seeping outward. However, groundwater around the tunnel will seep into the composite drainage board structure area along the open joints of the tunnel segments under the action of osmotic pressure difference. If the infiltrated groundwater cannot be discharged in a timely and effective manner, it will accumulate inside the structure, leading to problems such as structural seepage erosion, deterioration of structural performance, and disturbance of regional groundwater, directly affecting the long-term operational stability of the tunnel.

[0005] Composite drainage boards are functional components in modular linings that enable coordinated structural deformation and orderly seepage control. Their structural parameters determine key mechanical indicators (d / E) and ultimate drainage capacity. The d / E index directly controls the opening of the lining joints and is a sensitive parameter affecting the infiltration rate of external water into the tunnel. For urban water conveyance tunnels, excessive infiltration not only disturbs the original groundwater seepage field and causes environmental problems, but when the infiltration rate exceeds the drainage limit of the composite drainage board, it causes water accumulation inside the structure, continuously eroding the lining interface, deteriorating the overall mechanical properties of the structure, and significantly reducing the durability of the modular lining.

[0006] Currently, the determination of the d / E parameters of composite drainage boards in combined lined water conveyance tunnels generally relies on traditional empirical formulas or simplified mechanical calculation methods, and a systematic and precise parameter design system has not yet been formed. Existing technologies have obvious technical defects, as follows: First, the parameter calculation models have poor adaptability and low calculation accuracy. Existing empirical formulas and simplified calculation methods are based on idealized, static, and homogeneous stress assumptions, and do not consider the characteristics of actual engineering conditions such as high-pressure dynamic water conveyance loads, multi-layer lining coupled stress, and complex strata constraints. As a result, the calculated d / E parameters have a low degree of matching with the actual working conditions, and the accuracy of parameter selection is insufficient.

[0007] Second, there is a lack of a sound numerical verification mechanism. Existing technologies can only perform simple calculations of a single parameter and have not established a multi-field coupled numerical calculation model. Therefore, it is impossible to quantitatively compare and verify the structural deformation response, segment joint opening, and external water seepage control effect for different d / E parameter schemes. Parameter selection lacks reliable numerical theoretical support.

[0008] Third, the technology system is fragmented and lacks a closed-loop design logic. Existing technologies isolate structural stress analysis, seepage field calculation, and drainage capacity performance verification, failing to build an integrated design chain adapted to engineering realities. This makes it impossible to achieve coordinated matching of d / E parameters, structural deformation characteristics, and seepage drainage performance, thus hindering optimal parameter design.

[0009] Fourth, the technical solutions lack universality. Existing parameter determination methods are mostly designed for specific engineering conditions and do not systematically consider the influencing factors of multiple variables such as hydrogeological conditions, water conveyance pressure level, and tunnel structural dimensions, making them unsuitable for different types of urban high-pressure water conveyance tunnel projects.

[0010] In summary, existing technologies lack a theoretically sound, quantifiable, and adaptable systematic scheme for determining the d / E parameters of composite drainage boards. This makes it difficult to accurately control the infiltration of external water into combined-lined water conveyance tunnels, and hinders the balance between tunnel structural stability and regional groundwater environment safety. Therefore, to address the aforementioned technical deficiencies in existing technologies, a novel and systematic scheme for optimizing composite drainage board parameters and assessing infiltration of external water is urgently needed. Summary of the Invention

[0011] In order to overcome the above-mentioned defects in the prior art, the present invention provides a method and system for controlling external water seepage in a combined-lined water conveyance tunnel, particularly a method and system for controlling external water seepage in a combined-lined water conveyance tunnel based on the ratio of the composite drainage board thickness d to the elastic modulus E (d / E).

[0012] The technical solution adopted by this invention to solve its technical problem is: A method for controlling external water seepage in a combined-lined water conveyance tunnel includes the following steps: A numerical calculation model of the stress of the composite lining structure was established, and numerical calculation of internal water pressure loading under different composite drainage board d / E schemes was carried out, where d is the thickness of the composite drainage board and E is the elastic modulus of the composite drainage board. Extract the opening amount of the outer lining segment joint in the combined lining under each d / E scheme; A numerical calculation model of the seepage field of a combined-lined water conveyance tunnel was established, and seepage calculations of the water conveyance tunnel were performed under various d / E schemes. Extract the external water infiltration flow rate Q of the combined-lined water conveyance tunnel under each d / E scheme, ensuring that the tunnel infiltration flow rate is less than the drainage capacity of the composite drainage board; and Using curve fitting, based on the external water infiltration flow rate Q corresponding to different d / E schemes, the range of d / E values ​​for composite drainage boards that can meet the external water infiltration control standards for combined lined water conveyance tunnels is determined.

[0013] Furthermore, the steps for establishing a numerical calculation model of the stress on the composite lining structure include: Three-dimensional solid elements were used to simulate the pea gravel grouting layer, segment lining, self-compacting concrete, and composite drainage board. Shell elements are used to simulate steel pipes; Embedded rod units are used to simulate the bolts connecting the pipe segments; Surface-to-surface contact elements were used to simulate the interfaces between the tunnel lining and the gravel grouting layer, between the tunnel lining and the self-compacting concrete and composite drainage board, between the steel pipe and the self-compacting concrete, and between adjacent tunnel segments; and Grounding springs are used to characterize the constraint of the surrounding rock on the outward deformation of the lining structure.

[0014] Furthermore, the steps for extracting the opening amount of the outer lining segment joints in the combined lining under each d / E scheme include: Extract the joint opening of all nodes on the subordinate surface of each segment joint longitudinal joint face-to-face contact unit; and Calculate the average opening amount of each node, and use it as the opening amount of the longitudinal joint.

[0015] Furthermore, the steps for establishing a numerical calculation model of the seepage field in a combined-lined water conveyance tunnel include: Set the left, right and bottom boundaries of the surrounding rock to a preset multiple of the tunnel diameter, and take the top boundary to the ground surface; Pore-pressure coupled plane strain element was used to simulate the surrounding rock, gravel grouting layer, segment lining and self-compacting concrete; Zero-thickness cohesive elements are embedded at each joint of the tunnel lining to simulate the flow capacity of the joint; and Cohesive units are set at the interface between the pipe lining and the self-compacting concrete, wherein within the area where the composite drainage board is laid, the hydraulic opening of the cohesive unit is set to the width of the drainage gap of the composite drainage board.

[0016] Furthermore, the steps for extracting the external water infiltration flow rate Q of the combined-lined water conveyance tunnel under each d / E scheme include: The seepage flow rate of all pore pressure nodes of the cohesive unit within the range of the composite drainage board is extracted and used as the external water infiltration rate Q of the combined lining water conveyance tunnel.

[0017] Furthermore, the step of ensuring that the tunnel seepage flow is less than the drainage capacity of the composite drainage board includes: Calculate the water flow rate Q0 per unit width of the convex shell drainage board; and Verify Q <Q0。

[0018] Furthermore, the steps for calculating the water flow rate Q0 per unit width of the convex shell-type drainage board include: The equivalent pipe diameter D0 of the drainage channel per unit width of the convex shell drainage board is calculated based on the structural parameters of the convex shell drainage board, where D0 is calculated using the following formula: (1) Where L is the spacing between the convex shells of the convex shell drainage board, h is the height of the convex shell of the convex shell drainage board, B is the thickness of the convex shell drainage board, ε is the maximum allowable compressive deformation rate of the convex shell drainage board, b1 is the top diameter of the frustum-shaped convex shell drainage board, b2 is the bottom diameter of the frustum-shaped convex shell drainage board; and Based on hydraulic principles, the daily water flow rate Q0 of the convex shell drainage board is calculated according to the equivalent pipe diameter D0, where Q0 is calculated using the following formula: (2) Where J is the hydraulic gradient, A is the cross-sectional area of ​​the pipe, R is the hydraulic radius, and C is the Chezy coefficient.

[0019] Furthermore, the steps for determining the range of d / E values ​​for the composite drainage board using curve fitting include: Curve fitting was performed on the external water infiltration rate Q and the d / E value corresponding to different d / E schemes to obtain the fitted curve expression; and Based on the external water infiltration control standard [Q] for combined lined water conveyance tunnels and the fitted curve expression, the range of values ​​for d / E is determined by inequalities.

[0020] Furthermore, the expression for the fitted curve is as follows: (3) Where A is the value of the external water infiltration Q, x is the value of d / E, and a, b, c, B, and C are constants obtained from the fitting; the inequality for determining the range of d / E is: (4) The present invention also discloses an external water seepage control system for a combined-lined water conveyance tunnel, which is a computer program. When the computer program is executed by a processor, it implements the external water seepage control method for the combined-lined water conveyance tunnel described above.

[0021] The beneficial effects of this invention are: 1. Constructing a multi-field coupled integrated analysis system with a complete closed-loop technical system. This invention integrates structural stress simulation, seepage field calculation, and drainage capacity verification to form a complete technical chain of "parameter matching - structural deformation - seepage control - drainage verification," which solves the defects of existing technologies where each analysis link is isolated and the system is fragmented, and realizes integrated and collaborative analysis of the stress and seepage characteristics of tunnel structures.

[0022] 2. Achieves precise quantitative determination of parameters, significantly improving scientific rigor. This invention abandons the crude approach of traditional empirical formulas and simplified calculations. Through multi-condition numerical simulation combined with curve fitting, it establishes a quantitative correlation between the d / E parameter and the infiltration rate of external water. Based on seepage control standards, it precisely defines the reasonable range of d / E values, overcoming the problems of strong subjectivity, low accuracy, and poor adaptability to operating conditions of empirical methods, thus greatly improving the accuracy and scientific rigor of parameter selection.

[0023] 3. Strong engineering applicability. This invention constructs a refined numerical model based on actual engineering conditions, fully considering the complex characteristics such as coupled stress of multi-layer lining, joint seepage, and surrounding rock constraints. The calculation results closely match the actual operating conditions, providing reliable and practical quantitative technical basis for the selection of composite drainage board parameters and the prevention and control of external water seepage in tunnels.

[0024] 4. Excellent applicability. This invention breaks through the limitations of traditional technologies that are only applicable to a single engineering condition. The numerical model can be adapted to different hydrogeological conditions, water conveyance pressures, and tunnel structural parameters, and can be widely applied to the seepage control optimization design of composite-lined high-pressure water conveyance tunnels under various complex working conditions, with a wide range of applications.

[0025] 5. Balancing structural durability and groundwater environment safety. This invention optimizes the d / E parameter to control the infiltration of external water into the tunnel within the limits of drainage capacity and specifications, effectively avoiding structural water accumulation and erosion, mechanical property deterioration, and ensuring lining stability. At the same time, it reduces the disturbance of the tunnel operation to the regional groundwater seepage field, meeting the construction requirements for engineering safety. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a schematic diagram of the combined lining structure in an embodiment of the present invention; Figure 2 This is a schematic diagram of a three-dimensional finite element cracking calculation model for a combined lining tunnel in an embodiment of the present invention; Figure 3 This is a schematic diagram of the calculation model for external water seepage in a combined-lined water conveyance tunnel according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the detailed structure of the composite drainage board in an embodiment of the present invention; Figure 5 This is a schematic diagram of the composite drainage board structure dimensions in an embodiment of the present invention; Figure 6 This is a schematic diagram showing the variation of the opening amount of each joint of the outer lining segment of the combined lining in an embodiment of the present invention with d / E. Figure 7 This is a schematic diagram of the fitting curve of the seepage flow rate per unit pipe length and d / E in an embodiment of the present invention; Figure 8 This is a flowchart of a method for controlling the seepage of external water in a combined-lined water conveyance tunnel according to an embodiment of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It is understood that the specific embodiments described herein are only for explaining this application and not for limiting it. Furthermore, it should be noted that, for ease of description, only the parts related to this application are shown in the accompanying drawings, not all structures. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0028] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. The embodiments described herein may be combined with other embodiments.

[0030] Example 1: Method for controlling external water seepage in combined lined water conveyance tunnels This embodiment provides a method for controlling the infiltration of external water into a combined-lined water conveyance tunnel. This method, through systematic numerical calculations and parameter optimization, determines the key parameter d / E (the ratio of thickness d to elastic modulus E) of the composite drainage board, thereby effectively controlling the amount of external water infiltration into the water conveyance tunnel. For example... Figure 8 As shown, this method includes the following steps: Step S101: Establish a numerical calculation model of the stress of the composite lining structure and perform numerical calculation of internal water pressure loading under different composite drainage board d / E schemes.

[0031] This step aims to simulate the structural response of the composite lining under different d / E parameters.

[0032] Structural modeling: such as Figure 1 As shown, the combined lining structure in this embodiment includes an outer lining of tubular segments, an inner lining of steel pipes, and self-compacting concrete filling the space between the two, along with a laid composite drainage board. Specifically: The outer lining segment is assembled from one capping block (central angle 15°), two adjacent blocks (central angle 64.5°), and three standard blocks (central angle 72°), with an inner diameter of 5.8m and a thickness of 30cm.

[0033] The outer layer of the segment lining is a 15cm thick gravel backfill grout layer.

[0034] The inner diameter of the steel lining pipe is 5.2m, and the calculated wall thickness is 16mm.

[0035] A 30cm thick layer of C30 self-compacting concrete was backfilled between the steel pipe and the lining segments.

[0036] A composite drainage board with a thickness of d=15mm is laid within a 240° range on the upper part of the inner wall of the pipe segment lining.

[0037] Finite element model establishment: such as Figure 2 As shown, a three-dimensional finite element model for crack calculation is established by taking a single ring segment along the tunnel axis. The element type and material constitutive settings of the model are as follows: Gravel grouting layer, segment lining, self-compacting concrete and composite drainage board: all were simulated using three-dimensional solid elements (C3D8R), and their material parameters are shown in Table 1.

[0038] Table 1

[0039] Parameters for the plastic damage model of self-compacting concrete: ψ (shear dilatation angle) = 30°, (Flow potential offset) = 0.1, (Invariant stress ratio) = 0.67, σb0 / σc0 (ratio of biaxial compressive strength to uniaxial compressive strength) = 1.16, (Coefficient of viscosity) = 5 × 10 -4 . The self-compacting concrete model uses a concrete plastic damage model with the following parameters: shear dilatation angle ψ = 30°, and flow potential offset. =0.1, invariant stress ratio =0.67, the ratio of biaxial to uniaxial compressive ultimate strength σb0 / σc0=1.16, viscosity coefficient =5×10 -4 All other materials were modeled using a linear elasticity model.

[0040] Steel pipe and reinforcing ring: Simulated using three-dimensional shell elements (S4R), with Q345R material.

[0041] M30 bolts connecting the segments: simulated using embedded rod elements (T3D2), where the rod elements are completely embedded in the segment solid elements and do not slip.

[0042] Contact interfaces: Surface-to-surface contact elements are used to simulate the following interfaces: between the tunnel lining and the gravel grouting layer, between the tunnel lining and the self-compacting concrete and composite drainage board, between the steel pipe and the self-compacting concrete, and between adjacent tunnel segments. The composite drainage board and the self-compacting concrete are connected using shared nodes.

[0043] Boundary conditions: A grounding spring is used to characterize the constraint of the surrounding rock on the outward deformation of the lining structure. The spring stiffness is determined based on the elastic resistance coefficient of the surrounding rock (2866 MPa / m in this embodiment).

[0044] Load and Calculation Scheme: The load only considers the design internal water pressure P=1.355 MPa, which is uniformly applied to the inner surface of the steel pipe. By changing the comprehensive elastic modulus E of the composite drainage board, a series of different d / E schemes are obtained (d is fixed at 15mm), and numerical calculations of internal water pressure loading are performed.

[0045] Step S102: Extract the opening amount of the outer lining segment joint in the combined lining under each d / E scheme.

[0046] This step aims to obtain key deformation indicators that reflect the sealing performance of the lining.

[0047] After calculation, the joint opening (COPEN) of all nodes on the subordinate surface of the face-to-face contact unit at the longitudinal joint of each segment is extracted in post-processing. The arithmetic mean of these node openings is calculated as the final opening of the longitudinal joint. Thus, the opening of each joint of the outer lining segment in the composite lining can be obtained under all d / E schemes. The trend of the joint opening with the d / E value is as follows: Figure 6 As shown.

[0048] Step S103: Establish a numerical calculation model of the seepage field of the combined lined water conveyance tunnel and perform seepage calculations for the water conveyance tunnel under each d / E scheme.

[0049] This step aims to simulate the process of groundwater seeping into the tunnel through the open joints.

[0050] Model generalization and establishment: such as Figure 3 As shown, a numerical calculation model of the plane strain seepage field is established. The rock strata are regarded as a homogeneous isotropic medium. To reduce the boundary effect, the left, right and bottom boundaries of the model are taken to be more than 20 times the tunnel diameter (20D), and the top boundary is taken to the ground surface.

[0051] Unit and material settings: Surrounding rock, gravel grouting layer, segment lining, and self-compacting concrete: all were simulated using a four-node pore pressure coupled plane strain element (CPE4P). Their permeability coefficients were: surrounding rock 2×10⁻⁶ -6 m / s, gravel layer 1×10 -7 m / s, segment lining 1×10 -10 m / s, self-compacting concrete 1×10 -9 m / s.

[0052] Segment joints: Zero-thickness cohesive elements (COH2D4P) are embedded at each segment joint to simulate its flow capacity. The hydraulic opening is given by the joint opening amount calculated in the previous step.

[0053] Composite drainage board: Zero-thickness cohesive units (COH2D4P) are embedded within a 360° range at the interface between the pipe lining and the self-compacting concrete. Within a 240° range of the composite drainage board installation, the hydraulic opening of this cohesive unit is set to the width of the drainage joints within the composite drainage board itself (determined based on its structural dimensions, e.g., ...). Figure 5 As shown in the figure, to simulate its drainage channel; the hydraulic opening is set to 0 mm for the remaining 120° range.

[0054] Boundary condition settings: The left and right sides of the model are set as fixed pore pressure boundaries based on the actual groundwater level.

[0055] The tunnel top (surface) and the inner surface of the self-compacting concrete are designed as impermeable boundaries.

[0056] Within a 240° range of the simulated composite drainage board, the pore pressure of the cohesive unit is set to zero (free outflow boundary).

[0057] Fixed displacement constraints are applied to all nodes of the model.

[0058] Calculation execution: The joint opening amount corresponding to each d / E scheme obtained in step S102 is assigned to the corresponding joint element in the seepage model, and the steady-state seepage field is calculated in sequence.

[0059] Step S104: Extract the external water infiltration flow rate Q of the combined lined water conveyance tunnel under each d / E scheme, and ensure that the tunnel infiltration flow rate is less than the drainage capacity of the composite drainage board.

[0060] This step includes two key aspects: extracting seepage flow and verifying drainage capacity.

[0061] Extracting the seepage flow rate Q: After calculation, extract the seepage flow rate of all cohesive unit pore pressure nodes within the range of the composite drainage board (i.e., the 240° range), and sum them as the external water seepage rate Q per unit pipe length of the combined lining water conveyance tunnel under this d / E scheme. In this embodiment, the Q values ​​corresponding to different d / E values ​​are shown in Table 2.

[0062] Table 2

[0063] Verify drainage capacity: To ensure that the infiltrated groundwater can be discharged in a timely manner, it is necessary to verify that the seepage flow rate Q is less than the drainage flux Q0 of the composite drainage board itself.

[0064] Calculate the drainage board flux Q0: a. Calculate the equivalent pipe diameter D0: The composite drainage board is a frustum-shaped convex shell, and its structure is as follows: Figure 4 As shown, (a) represents the drainage channel structure, and (b) represents the cross-sectional structure of the convex shell type drainage board. The structural dimensions are as follows: Figure 5 As shown, the specific parameters are: convex shell spacing L=25mm, convex shell height h=10mm, plate thickness B=1.5mm, top surface diameter b1=bottom surface diameter b2=12mm, and maximum compression deformation rate ε=0.1. Calculate the equivalent drainage pipe diameter D0 of the drainage board per unit width (1 linear meter) according to formula (1).

[0065] The equivalent pipe diameter per unit width (per meter longitudinal length of the tunnel) of the frustum-shaped convex shell drainage board drainage channel is: (1) In the formula: D0 is the equivalent pipe diameter of the drainage channel of the convex shell drainage board per unit width (longitudinal extension meter of the tunnel); L is the convex shell spacing of the convex shell drainage board; h is the convex shell height of the convex shell drainage board; B is the thickness of the convex shell drainage board; ε is the maximum allowable compressive deformation rate of the convex shell drainage board under a pressure of 120 kPa, which is taken as 0.1; b1 is the top diameter of the frustum-shaped convex shell drainage board; b2 is the bottom diameter of the frustum-shaped convex shell drainage board.

[0066] b. Calculate the water flow rate Q0: According to the hydraulic principle, calculate the daily water flow rate of the drainage board using formula (2).

[0067] (2) In the formula: Q0 is the water flow rate per unit width (per meter longitudinally of the tunnel) of the convex shell drainage board; J is the hydraulic gradient, ranging from 0.1 to 1.0; A is the cross-sectional area of ​​the pipe (m2); R is the hydraulic radius, R = cross-sectional area of ​​the pipe / inner wall perimeter (m); C is the Chezy coefficient, C = R1 / 6 / n (m0.5 / s); n is the roughness coefficient, ranging from 0.011 to 0.014 depending on the smoothness of the pipe wall.

[0068] Calculations show that the drainage flux Q0 of the convex shell-type drainage board used in this embodiment is 542 m³. 3 / d ~ 2181 m 3 Between / d.

[0069] Proficiency testing: Compare the Q values ​​in Table 2 (maximum is 26.0 m). 3 The condition Q < Q0 is clearly satisfied, which proves that the composite drainage board has sufficient capacity to discharge the infiltrated water.

[0070] Step S105: Use curve fitting method to determine the range of d / E values ​​for composite drainage boards that can meet the standards for controlling the amount of water seepage inside combined lined water conveyance tunnels.

[0071] This step uses mathematical methods to determine the parameter thresholds that meet engineering control standards.

[0072] Curve fitting: Using the d / E values ​​and corresponding seepage flow rates Q in Table 2 as data points, a nonlinear least squares method was used for curve fitting. The fitted curve is shown below. Figure 7 The curve shown is expressed by formula (3): (3) Where A represents the value of seepage flow Q, x represents the value of d / E, and a, b, c, B, and C are fitting constants. In this embodiment, the fitting results are: a = -0.14, b = 0.234, c = 3.225, B = 9421076, C = 44.40.

[0073] Determine the parameter range: Based on the external water infiltration control standard [Q] = 1.5m for water conveyance tunnels traversing urban environments. 3 / m / d, substituting the control standard into the fitted curve, we obtain inequality (4): (4) Substituting the fitting constants and solving this inequality, we obtain the range of values ​​for d / E: d / E ≥ x1 mm3 / N, where x1 = 10.5.

[0074] Design Application: In engineering design, simply ensure that the ratio of the thickness d of the selected composite drainage board to its comprehensive elastic modulus E is greater than 10.5 mm. 3 / N ensures that the external water seepage per unit length of the combined-lined water conveyance tunnel does not exceed 1.5 m during operation. 3 / m / d control standard.

[0075] Example 2: External Water Infiltration Control System for Combined Lined Water Conveyance Tunnels This embodiment provides an external water infiltration control system for a combined lined water conveyance tunnel, which is a computer program product used to automatically implement the control method described in Embodiment 1.

[0076] System Architecture: This system can be deployed on a server or high-performance computing workstation and includes the following modules: Preprocessing module: used to input engineering parameters (such as material parameters in Table 1, etc.). Figure 1 (Structural dimensions, internal water pressure, surrounding rock resistance coefficient, etc.) automatically generate finite element models and seepage field model meshes as described in steps S101 and S103.

[0077] Solver interface module: Calls the solver kernel of finite element software (such as ABAQUS) or integrates a self-developed numerical calculation engine to perform internal water pressure loading calculation and seepage field calculation.

[0078] Post-processing and extraction module: Automatically extracts key data such as segment joint opening and tunnel seepage flow Q from the calculation result file.

[0079] Analysis and optimization module: Built-in formulas (1) and (2) are used to calculate the drainage board flux Q0 and automatically verify Q < Q0; Built-in curve fitting algorithm can automatically fit formula (3) and solve inequality (4) based on the calculation results of multiple input d / E schemes, and finally output the d / E value range that meets the control standard.

[0080] User Interface Module: Provides a graphical interface for engineers to easily input parameters, monitor the calculation process, and view and export calculation results and charts (such as...). Figure 6 , Figure 7 ).

[0081] Workflow: Users input basic engineering parameters and several preset d / E values ​​through the interface. The system automatically completes the entire process from modeling, calculation, extraction, verification to parameter optimization, and finally outputs a report recommending the range of d / E values ​​for composite drainage boards.

[0082] Storage medium: The computer program can be stored in a computer-readable storage medium, such as ROM, RAM, magnetic disk, optical disk, cloud storage, etc. When the computer program in the storage medium is executed by a processor (such as the CPU of a computer), it can implement all or part of the method steps.

[0083] The above description is merely an embodiment of this application and does not limit the scope of this application. Any equivalent structural or procedural changes made based on the description and drawings of this application, or direct or indirect applications in other related technical fields, are similarly included within the protection scope of this application.

Claims

1. A method for controlling external water seepage in a combined-lined water conveyance tunnel, characterized in that, Includes the following steps: A numerical calculation model of the stress of the composite lining structure was established, and numerical calculation of internal water pressure loading under different composite drainage board d / E schemes was carried out, where d is the thickness of the composite drainage board and E is the elastic modulus of the composite drainage board. Extract the opening amount of the outer lining segment joint in the combined lining under each d / E scheme; A numerical calculation model of the seepage field of a combined-lined water conveyance tunnel was established, and seepage calculations of the water conveyance tunnel were performed under various d / E schemes. Extract the external water infiltration flow rate Q of the combined-lined water conveyance tunnel under each d / E scheme, ensuring that the tunnel infiltration flow rate is less than the drainage capacity of the composite drainage board; and Curve fitting was performed on the external water infiltration rate Q and the d / E value corresponding to different d / E schemes to obtain the fitted curve expression; and based on the external water infiltration rate control standard [Q] of the combined lined water conveyance tunnel and the fitted curve expression, an inequality was constructed to determine the range of d / E values, where the external water infiltration rate control standard [Q] = 1.5 m 3 / m / d.

2. The method for controlling external water seepage in a combined-lined water conveyance tunnel according to claim 1, characterized in that, The steps for establishing a numerical calculation model of the stress on a composite lining structure include: Three-dimensional solid elements were used to simulate the pea gravel grouting layer, segment lining, self-compacting concrete, and composite drainage board. Shell elements are used to simulate steel pipes; Embedded rod units are used to simulate the bolts connecting the pipe segments; Surface-to-surface contact elements were used to simulate the interfaces between the tunnel lining and the gravel grouting layer, between the tunnel lining and the self-compacting concrete and composite drainage board, between the steel pipe and the self-compacting concrete, and between adjacent tunnel segments; and Grounding springs are used to characterize the constraint of the surrounding rock on the outward deformation of the lining structure.

3. The method for controlling external water seepage in a combined-lined water conveyance tunnel according to claim 1, characterized in that, The steps for extracting the opening of the outer lining segment joints in the combined lining under each d / E scheme include: Extract the joint opening of all nodes on the subordinate surface of each segment joint longitudinal joint face-to-face contact unit; and calculate the average value of the opening of each node as the opening of the longitudinal joint.

4. The method for controlling external water seepage in a combined-lined water conveyance tunnel according to claim 1, characterized in that, The steps for establishing a numerical model of the seepage field in a combined-lined water conveyance tunnel include: Set the left, right and bottom boundaries of the surrounding rock to a preset multiple of the tunnel diameter, and take the top boundary to the ground surface; Pore-pressure coupled plane strain element was used to simulate the surrounding rock, gravel grouting layer, segment lining and self-compacting concrete; Zero-thickness cohesive units are embedded at each joint of the tunnel lining to simulate the flow capacity of the joint; and cohesive units are set at the interface between the tunnel lining and the self-compacting concrete, wherein within the area where the composite drainage board is laid, the hydraulic opening of the cohesive unit is set to the drainage gap width of the composite drainage board.

5. The method for controlling external water seepage in a combined-lined water conveyance tunnel according to claim 1, characterized in that, The steps for extracting the external water infiltration flow rate Q of the combined lining water conveyance tunnel under each d / E scheme include: extracting the infiltration flow rate of all pore pressure nodes of the cohesive unit within the range of the composite drainage board, as the external water infiltration flow rate Q of the combined lining water conveyance tunnel.

6. The method for controlling external water seepage in a combined-lined water conveyance tunnel according to claim 1, characterized in that, The steps to ensure that the tunnel seepage flow is less than the drainage capacity of the composite drainage board include: calculating the water flow rate Q0 per unit width of the convex shell drainage board; and verifying Q. <Q0。 7. The method for controlling external water seepage in a combined-lined water conveyance tunnel according to claim 6, characterized in that, The steps for calculating the water flow rate Q0 per unit width of a convex shell drainage board include: The equivalent pipe diameter D0 of the drainage channel per unit width of the convex shell drainage board is calculated based on the structural parameters of the convex shell drainage board, where D0 is calculated using the following formula: （1） Where L is the spacing between the convex shells of the convex shell drainage board, h is the height of the convex shell of the convex shell drainage board, B is the thickness of the convex shell drainage board, ε is the maximum allowable compressive deformation rate of the convex shell drainage board, b1 is the top diameter of the frustum-shaped convex shell drainage board, b2 is the bottom diameter of the frustum-shaped convex shell drainage board; and Based on hydraulic principles, the daily water flow rate Q0 of the convex shell drainage board is calculated according to the equivalent pipe diameter D0, where Q0 is calculated using the following formula: （2） Where J is the hydraulic gradient, A is the cross-sectional area of ​​the pipe, R is the hydraulic radius, and C is the Chezy coefficient.

8. The method for controlling external water seepage in a combined-lined water conveyance tunnel according to claim 1, characterized in that, The expression for the fitted curve is as follows: （3） Where A is the value of the external water infiltration Q, x is the value of d / E, and a, b, c, B, and C are constants obtained from the fitting; the inequality for determining the range of d / E is: （4） 。 9. A computer program product, characterized in that, The computer program product includes a computer program stored in a computer-readable storage medium, which, when executed by a processor, implements the combined-lined water conveyance tunnel external water seepage control method as described in any one of claims 1-8.

Images