A hydraulic tunnel lining structure based on ductility short segment and a design method thereof

Abstract

The application discloses a hydraulic tunnel lining structure based on ductility short split segments and a design method thereof. The lining structure comprises annular concrete lining segments and ductility short split lining segments. The concrete lining segments and the ductility short split lining segments are arranged alternately along the tunnel axial direction. Flexible narrow gaps are arranged between adjacent concrete lining segments and ductility short split lining segments. Flexible fillers are filled in the flexible narrow gaps. Two annular two-cloth-one-film structures and one annular water stop structure are arranged in the flexible narrow gaps along the lining thickness direction and are circumferentially wrapped by the flexible fillers. The water stop structure is located between the two annular two-cloth-one-film structures. The two ends of the water stop structure and the two-cloth-one-film structures are anchored to the concrete lining segments and the ductility short split lining segments respectively. The design method is used for determining the width of the flexible narrow gaps and the length of the concrete lining segments and the ductility short split lining segments. The application effectively suppresses lining damage concentration and shear strain development, and realizes displacement coordination and high-pressure anti-seepage.

Description

Technical Field

[0001] This invention belongs to the field of water conservancy and hydropower engineering technology, specifically relating to a hydraulic tunnel lining structure based on ductile short segments, and also to a design method for a hydraulic tunnel lining structure based on ductile short segments, applicable to the seismic design of high-pressure hydraulic tunnels crossing active fault zones. Background Technology

[0002] Hydraulic tunnels, as key control structures in water conservancy and hydropower projects, play an irreplaceable role in inter-basin water resource allocation and hydropower energy development. However, the complex geological structure and dense distribution of active faults in western my country mean that the construction of hydraulic tunnels inevitably faces the challenge of traversing active faults. The displacement of active faults induces intense stress redistribution and large-scale plastic deformation in the surrounding rock, directly threatening the load-bearing capacity and long-term service performance of the tunnel lining structure. Therefore, conducting fault-resistant design for tunnels crossing faults is of significant engineering importance.

[0003] To address the issue of fault-resistant tunneling through active faults, existing technologies mainly employ adaptive measures such as articulated design, over-excavation to reserve deformation space, or the installation of isolation and energy dissipation layers. Examples include the literature: "Liu Xuezeng, Guo Biao, Li Xuefeng, et al. Model test study on the influence of deformation joints on fault-resistant tunnels [J]. Chinese Journal of Rock Mechanics and Engineering, 2015, 34(S2)." and "Cui Zhen, Zhang Yanjie, Zhou Guangxin, et al. Adaptive structural response analysis of fault-resistant tunnels crossing active faults [J]. Journal of Yangtze River Scientific Research Institute, 2022, 39(12)." Among these, articulated design is widely recognized in the engineering community due to its ability to effectively coordinate structural deformation and disperse concentrated stress. Traditional articulated anti-fault dislocation schemes typically shorten the lining segment length and appropriately increase the width of the flexible joint between segments, utilizing the elastic deformation of the joint filling material or the reserved geometric space to absorb fault displacement, as seen in the literature "Li Xuefeng, Dai Zhiping, Gu Xueying, et al. Influence of deformation joint spacing on tunnel internal forces under active fault displacement [J]. Tunnel Construction, 2014, 34(3)", "Zhao Kun, Chen Weizhong, Zhao Wusheng, et al. Study on design parameters of tunnel lining articulation under reverse fault displacement [J]. Chinese Journal of Rock Mechanics and Engineering, 2018, 37(S1)", and "Zhang Jiawei, Cui Zhen, Zhang Xiangyu, et al. Experimental study on anti-fault articulation design of tunnels across active faults under high ground stress [J]. Rock and Soil Mechanics, 2024, 45(11)".

[0004] However, for hydraulic tunnels subjected to high internal water pressure, the aforementioned traditional articulated joint design has significant technical bottlenecks: excessively wide physical joints severely weaken the overall seepage prevention continuity of the lining structure. Under the coupled effect of fault displacement deformation and high internal water pressure, wide joints easily become weak channels for high-pressure water seepage, which not only exacerbates the loss and aging of joint filling materials but may also lead to disasters such as softening of surrounding rock and even overall structural instability. Existing technologies focus on improving the structure's resistance to fault deformation but lack a comprehensive consideration of deformation coordination performance and seepage prevention performance. The traditional approach of "exchanging deformation for wide joints" is difficult to directly apply to high-pressure hydraulic tunnels.

[0005] Therefore, there is an urgent need to propose a new type of anti-fault lining structure and a corresponding optimization design method. At the structural level, while retaining the advantages of hinged design in deformation coordination, the width of physical joints should be effectively reduced. At the methodological level, a scientific parameter optimization design process needs to be established to clarify the matching rules and primary and secondary influence weights of key variables such as the length of conventional concrete segments, the length of ductile short segments, and the width of flexible joints. Ultimately, through the synergistic innovation of the physical structure and the optimization method, the dual goals of deformation coordination and high-pressure seepage prevention can be achieved to meet the needs of safe construction and long-term operation of high-pressure hydraulic tunnels under complex geological conditions. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned problems in the existing technology by providing a hydraulic tunnel lining structure based on ductile short segments and its design method. This solves the problems that traditional wide-joint designs are prone to causing high-pressure water seepage, softening of surrounding rock, and lining instability under the dual effects of fault displacement and high internal water pressure. At the same time, it provides a scientific and quantifiable parameter optimization design process to ultimately achieve the dual goals of deformation coordination and high-pressure seepage prevention.

[0007] The above-mentioned objectives of the present invention are achieved through the following technical means: A hydraulic tunnel lining structure based on ductile short segments includes annular concrete lining segments and annular ductile short segment lining segments. The concrete lining segments and ductile short segment lining segments are alternately arranged along the tunnel axis. Annular flexible narrow joints are provided between adjacent concrete lining segments and ductile short segment lining segments. The flexible narrow joints are filled with annular flexible filler. Two annular two-layer fabric-one-membrane and one annular water-stop structure are arranged in the flexible narrow joints along the lining thickness direction and are wrapped circumferentially by the flexible filler. The water-stop structure is located between the two layers of two-layer fabric-one-membrane. The two ends of the water-stop structure and the two-layer fabric-one-membrane are anchored to the concrete lining segments and ductile short segment lining segments, respectively.

[0008] The concrete lining segments are cast using concrete with a strength grade of not less than C30, and the ductile short lining segments are cast integrally using high-ductility concrete, which is a high-ductility fiber-reinforced cement-based composite material.

[0009] The mechanical parameters of the high-ductility concrete at a curing age of 28 days are as follows: compressive strength greater than or equal to 25 MPa and less than or equal to 40 MPa, elastic modulus less than or equal to 20 GPa, ultimate tensile strain greater than or equal to 1%, and crack width less than or equal to 100 μm when the ultimate bearing capacity is reached.

[0010] The water-stopping structure is a W-shaped copper water-stopping strip.

[0011] The flexible packing material is GB flexible packing material.

[0012] A design method for hydraulic tunnel lining structures based on ductile short segments, applicable to the aforementioned hydraulic tunnel lining structures based on ductile short segments, is characterized by comprising the following steps: Step 1: Obtain the basic design parameters and site survey parameters of the target tunnel project; Step 2: Determine the key geometric parameters for structural optimization design and select structural response data as the evaluation index for anti-fracture performance; Step 3: Determine the corresponding horizontal values ​​of the key geometric parameters and establish an orthogonal test scheme. Based on the basic design parameters and site survey parameters, construct a three-dimensional refined numerical model. Adjust the key geometric parameters in the three-dimensional refined numerical model according to the orthogonal test scheme and perform simulation calculations to obtain the structural response data of each group of orthogonal working conditions. Step 4: Perform orthogonal range analysis and multi-factor sensitivity analysis on the structural response data under each group of orthogonal working conditions to obtain the target level combination of key geometric parameters of the three-dimensional refined numerical model.

[0013] The basic design parameters include the tunnel excavation inner diameter, lining thickness, maximum horizontal displacement for protection, and maximum internal water pressure for design. The site investigation parameters include the type of fault the target tunnel crosses, fault orientation, surrounding rock physical and mechanical parameters, and initial geostress field characteristics.

[0014] The key geometric parameters include geometric parameter A, geometric parameter B, and geometric parameter C. Geometric parameter A is the length of the concrete lining segment, geometric parameter B is the length of the ductile short sub-lining segment, and geometric parameter C is the width of the flexible narrow joint. The structural response data used as evaluation indicators for resistance to fracture include the peak value of the volumetric damage index Y1, the peak value of the maximum shear strain Y2, and the peak value of the x-axis compressive deformation Y3.

[0015] The acquisition of structural response data under each group of orthogonal working conditions is based on the following steps: Determine the level values ​​corresponding to geometric parameters A, B, and C, using L9(3) 4Orthogonal arrays were used to formulate orthogonal test schemes. Based on the basic design parameters and site survey parameters of the target tunnel project, a three-dimensional refined numerical model was established using finite element software. Geometric parameters A, B, and C in the three-dimensional refined numerical model were adjusted according to the orthogonal test scheme. Simulation calculations were performed according to the preset load step sequence to obtain the structural response data of each group of orthogonal working conditions. Among them, L9(3 4 The first three columns of the orthogonal array correspond to geometric parameters A, B, and C, respectively, while the fourth column is a blank column used for error estimation.

[0016] The target level combination of key geometric parameters for obtaining the three-dimensional refined numerical model is based on the following steps: Orthogonal range analysis and multi-factor sensitivity analysis were performed on the structural response data under each group of orthogonal working conditions to obtain the sum, mean, range, and order of influence of factors for each key geometric parameter under different structural response data. A correspondence was established between the structural response data and the level values ​​of the key geometric parameters. For each structural response data, the target level combination of the key geometric parameters corresponding to that data was obtained according to the principle of minimizing the mean. The target level of the same key geometric parameter in each target level combination was extracted and a consistency judgment was performed: if the target level of a certain key geometric parameter is consistent across all structural response data, then that target level is determined as the comprehensive selected level for that key geometric parameter. If the target levels of a certain key geometric parameter are inconsistent under different structural response data, a certain target level of the key geometric parameter under different structural response data is selected as the comparison benchmark. Each target level of the key geometric parameter is compared with the comparison benchmark. The increase in each structural response data during the comparison process is recorded as the deterioration of the structural response data at the corresponding target level. The sum of the deterioration of each structural response data at the target level is taken as the total deterioration of the target level. The target level with the smallest total deterioration is selected as the comprehensive selected level of the key geometric parameter. Finally, the comprehensive selected levels of each key geometric parameter are combined to obtain the target level combination of the key geometric parameters of the three-dimensional refined numerical model.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention establishes a flexible narrow joint between concrete lining segments and ductile short sub-lining segments, fills the joint with flexible filler, and simultaneously incorporates two annular layers of fabric and membrane, along with a water-stopping structure, along the thickness direction within the flexible filler, forming a "skeleton-filler" composite waterproofing and deformation coordination system. This system utilizes the flexible narrow joint and ductile segments to release relative rotation and axial compression deformation between adjacent segments, preventing the lining structure from cracking due to stress concentration. Furthermore, through the primary water-stopping function of the water-stopping structure, the auxiliary seepage prevention function of the fabric and membrane, and the deformation buffering and lateral restraint function of the flexible filler, it maintains good sealing performance even under repeated joint deformation conditions. This effectively solves the technical problems of easy leakage in traditional deformation joints and easy failure of waterstops, significantly improving the durability and operational safety of tunnel lining structures. 2. A design method is provided to complement the hydraulic tunnel lining structure based on ductile short segments, reducing the trial-and-error cost of traditional empirical design parameter selection. Attached Figure Description

[0018] Figure 1 This is a longitudinal sectional view of the lining structure of the present invention; Figure 2 This is a cross-sectional view of the lining structure of the present invention; Figure 3 This is a schematic diagram of the flexible narrow joint (transverse construction joint) structure of the lining structure of the present invention; Figure 4 A comparison of uniaxial tensile stress-strain curves between high-ductility concrete and C30 concrete; Figure 5 A flowchart illustrating the design method for hydraulic tunnel lining structures based on ductile short segments; Figure 6 This is a schematic diagram of a three-dimensional refined numerical model, where the arrows indicate the direction of displacement. Figure 7 The figures are stress-strain curves of high ductility concrete, where (a) is the stress-strain curve of high ductility concrete under compression, and (b) is the stress-strain curve of high ductility concrete under tension. Figure 8 The following are trend graphs showing the variation of various structural response data with the horizontal values ​​of key geometric parameters (length of concrete lining segment, length of ductile short sub-lining segment, and width of flexible narrow joint). Among them, (a) is the trend graph of structural response data Y1 with the horizontal values ​​of key geometric parameters, (b) is the trend graph of structural response data Y2 with the horizontal values ​​of key geometric parameters, and (c) is the trend graph of structural response data Y3 with the horizontal values ​​of key geometric parameters. Figure 9A comparative curve of the transverse (x-direction) compressive deformation of the tunnel cross section under fault displacement for different lining schemes; Figure 10 The distribution curves of the cross-sectional volumetric damage index (DVR) along the tunnel axis for different lining schemes are shown. Figure 11 A bar chart showing the maximum shear strain of the lining under fault displacement for different lining schemes; In the figure: 1-concrete lining segment, 2-ductile short sub-lining segment, 3-flexible narrow joint, 4-two layers of fabric and one membrane, 5-water-stopping structure, 6-flexible filler, 7-upper plate, 8-lower plate, 9-affected zone, 10-core. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present invention, the structural features and supporting optimization design methods of the present invention will be further described in detail below with reference to embodiments. It should be understood that the embodiments described herein are for illustration and explanation only and are not intended to limit the scope of protection of the present invention.

[0020] Example 1:

[0021] like Figure 1 As shown, a hydraulic tunnel lining structure based on ductile short segments includes concrete lining segments 1 and ductile short segment lining segments 2 arranged alternately along the tunnel axis, with a flexible narrow joint 3 provided between adjacent concrete lining segments 1 and ductile short segment lining segments 2. Figure 2 As shown, both the concrete lining segment 1 and the ductile short sub-lining segment 2 are annular, therefore the flexible narrow joint 3 is also annular. Figure 3 As shown, the flexible narrow joint 3 is filled with annular flexible filler 6. Two annular layers of geotextile and geomembrane 4 and an annular water-stopping structure 5 are arranged along the lining thickness direction in the flexible narrow joint 3 and are circumferentially wrapped by the flexible filler 6. The water-stopping structure 5 is located between the two layers of geotextile and geomembrane 4. The ends of the water-stopping structure 5 and the two layers of geotextile and geomembrane 4 are anchored to the concrete lining segment 1 and the ductile short sub-lining segment 2, respectively. The two layers of geotextile and geomembrane 4 form two waterproof layers, which, together with the water-stopping structure, constitute a multiple waterproof barrier, which can significantly improve the waterproof performance of the flexible narrow joint 3. It should be noted that the geotextile and geomembrane 4 is a seepage-proof material made of two layers of non-woven geotextile sandwiching a layer of geomembrane through hot pressing.

[0022] In some embodiments, the flexible filler 6 is made of GB flexible filler (butyl rubber sealant).

[0023] The concrete lining segment 1 is formed by pouring concrete with a strength grade of not less than C30.

[0024] The ductile short lining segment 2 is integrally cast using high-ductility concrete. The high-ductility concrete is a high-ductility fiber-reinforced cement-based composite material. The raw materials of the high-ductility concrete include 42.5 grade silicate cement, fly ash, artificial sand, polymer fibers, water-reducing agent and water. The polymer fibers are selected from polyvinyl alcohol fibers (PVA fibers).

[0025] The preferred mechanical parameters of high-ductility concrete at a standard curing age of 28 days are: compressive strength between 25 MPa and 40 MPa, ensuring that the ductile short lining segment 2 meets the basic requirements for lining bearing capacity and forms a reasonable strength matching relationship; elastic modulus not exceeding 20 GPa, significantly lower than C30 concrete, the lower elastic modulus is conducive to inducing relative rotation and axial deformation between concrete lining segment 1 and ductile short lining segment 2, which is concentrated and released at the flexible narrow joint 3, fully utilizing the deformation coordination ability of the flexible narrow joint 3, and avoiding structural cracking caused by deformation accumulation in concrete lining segment 1; ultimate tensile strain exceeding 1%, ensuring that the ductile short lining segment 2 does not undergo brittle fracture; and crack width not exceeding 100 μm when reaching ultimate bearing capacity, the fine cracks can significantly improve the impermeability of the ductile short lining segment 2. Figure 4 As shown, Figure 4 This is a comparison of uniaxial tensile stress-strain curves between high-ductility concrete and C30 concrete (strain values ​​magnified 10 times), both meeting the above-mentioned performance requirements. The comparison shows that the ultimate tensile strain of the high-ductility concrete is significantly greater than that of C30 concrete.

[0026] In some embodiments, the water-stopping structure 5 is a W-shaped copper water-stopping strip.

[0027] In some embodiments, the ductile short sub-lining segment 2 preferentially absorbs and bears the tensile and shear deformation of the lining structure through its own ductility, while the flexible narrow slot 3 mainly releases the relative rotation and axial compression deformation between the concrete lining segment 1 and the ductile short sub-lining segment 2.

[0028] The lining structure of this invention does not employ the traditional method of widening joints, but instead uses flexible narrow joints 3 and ductile short sub-lining segments 2 to replace wide joints. Specifically, by using flexible narrow joints 3 and ductile short sub-lining segments 2, these segments can generate a coordinated deformation capacity similar to that of wide joints under fault displacement, thereby effectively absorbing displacement. The physical joint width of this invention is significantly reduced, retaining the advantages of coordinated deformation in hinged designs while also meeting the overall structural requirements for high-pressure seepage prevention.

[0029] Example 2:

[0030] To achieve the optimal parameter configuration of the hydraulic tunnel lining structure based on ductile short segments as described in Example 1 under specific geological and hydrological conditions, this invention provides a set of standardized engineering optimization design methods.

[0031] like Figure 5 As shown, a design method for a hydraulic tunnel lining structure based on ductile short segments is applicable to the hydraulic tunnel lining structure based on ductile short segments described in Example 1, and includes the following steps: Step 1: Obtain the basic design parameters and site survey parameters of the target tunnel project.

[0032] Taking a high-pressure water conveyance tunnel across a fault in a high-intensity seismic zone in western China as an example, the basic design parameters of the target tunnel project are obtained: the tunnel excavation inner diameter is 11.6m, the lining thickness is 1.5m, the maximum horizontal displacement is designed to be δ=30cm, and the maximum internal water pressure is designed to withstand is 2MPa. The site investigation parameters include: the type of fault crossed by the target tunnel, the fault attitude, the physical and mechanical parameters of the surrounding rock, and the characteristics of the initial geostress field. In this embodiment, the fault type crossed by the target tunnel is an active fault with strike-slip displacement, the fault attitude is a fault dip angle of 80°, the physical and mechanical parameters of the surrounding rock are shown in Table 1, and the characteristics of the initial geostress field are shown in Table 2. The above basic design parameters and site investigation parameters are used to determine the geometric boundaries, initial geostress field, and load application boundary conditions of the subsequent three-dimensional refined numerical model.

[0033] Table 1 shows the values ​​of the physical and mechanical parameters of the surrounding rock.

[0034] Table 2 shows the characteristic values ​​of the initial geostress field.

[0035] Step 2: Select three geometric parameters as key geometric parameters for structural optimization design, and select three structural response data as evaluation indicators for anti-fracture performance.

[0036] Based on the structural deformation mechanism and engineering feasibility, the following three geometric parameters were selected as key geometric parameters for structural optimization design: the length of the concrete lining segment, denoted as geometric parameter A, with a horizontal value of 6-10m; the length of the ductile short sub-lining segment, denoted as geometric parameter B, with a horizontal value of 1-3m; and the width of the flexible narrow joint, denoted as geometric parameter C, with a horizontal value of 2-6cm. Simultaneously, three structural response data points for the hydraulic tunnel lining structure were selected as evaluation indicators for its resistance to faulting. These structural response data included: the peak value of the Damage Volume Ratio (DVR) Y1, used to characterize the overall damage degree of the lining section (dimensionless); the peak value of the maximum shear strain Y2, used to characterize the shear deformation response of the lining under faulting action; and the peak value of the x-direction (perpendicular to the axial direction) compressive deformation Y3, used to characterize the lining's lateral compressive deformation and overall deformation coordination ability. The smaller the values ​​of these three evaluation indicators, the better the resistance to faulting of the lining structure.

[0037] Step 3: Determine the corresponding horizontal values ​​of the key geometric parameters (geometric parameter A, geometric parameter B, and geometric parameter C) and establish an orthogonal test scheme. Based on the basic design parameters and site survey parameters, construct a three-dimensional refined numerical model. Adjust the key geometric parameters in the three-dimensional refined numerical model according to the orthogonal test scheme and perform simulation calculations to obtain the structural response data of each group of orthogonal working conditions.

[0038] The horizontal values ​​corresponding to geometric parameters A, B, and C are determined as shown in Table 3. Table 3 is a table of horizontal values ​​for key geometric parameters. The first level A1, the second level A2, and the third level A3 of geometric parameter A (length of concrete lining segment) are 6m, 8m, and 10m, respectively. The first level B1, the second level B2, and the third level B3 of geometric parameter B (length of ductile short lining segment) are 1m, 2m, and 3m, respectively. The first level C1, the second level C2, and the third level C3 of geometric parameter C (width of flexible narrow joint) are 2cm, 4cm, and 6cm, respectively.

[0039] Table 3 shows the level values ​​for the key composite parameters.

[0040] Using L9(3) 4 Orthogonal arrays are used to formulate orthogonal experimental schemes, where L9(3 4 The first three columns of the orthogonal array correspond to geometric parameters A, B, and C, respectively, while the fourth column is a blank column used for error estimation.

[0041] Based on the basic design parameters and site survey parameters of the target tunnel project, a refined three-dimensional numerical model incorporating the interaction between surrounding rock, fault, and lining was established using the finite element software FLAC3D. Figure 6 As shown, Figure 6 This is a schematic diagram of a refined three-dimensional numerical model. In the attached diagram, label 7 represents the hanging wall (fixed side), label 8 represents the footwall (faulted side), label 9 represents the influence zone, and label 10 represents the core. The arrows indicate the direction of faulting. The geometric dimensions of the lining structure in the refined three-dimensional numerical model are determined based on the tunnel excavation inner diameter of 11.6m and the lining thickness of 1.5m. Parameters for the surrounding rock materials in the refined three-dimensional numerical model are assigned based on the physical and mechanical parameters of the surrounding rock. The spatial location and attitude of the fault zone in the refined three-dimensional numerical model are determined based on the fault dip angle of 80°.

[0042] The simulation calculations were performed according to the following load sequence: first, the initial geostress field was applied and solved to equilibrium; then, the tunnel excavation was simulated and support was applied; subsequently, internal water pressure was applied to the inner surface of the lining in stages until the maximum internal water pressure of 2 MPa was reached; finally, the horizontal displacement of the fault was applied along the strike-slip direction until the maximum horizontal displacement δ=30cm was reached.

[0043] The lining material adopts a concrete constitutive model, such as Figure 7 (a) and Figure 7 As shown in (b), Figure 7 (a) is a stress-strain curve of high-ductility concrete under compression. Figure 7 (b) shows the stress-strain relationship curve of high-ductility concrete under tensile conditions. After the calculation of each group of orthogonal working conditions is completed, the finite element software extracts the structural response data (Y1, Y2, Y3) of each group of orthogonal working conditions to provide support for subsequent optimization analysis.

[0044] It should be noted that each orthogonal working condition group refers to L9(3 4 Nine test conditions are formed by different factors and their level combinations in the orthogonal array. The factors include the length of the concrete lining segment, the length of the ductile short sub-lining segment, and the width of the flexible narrow joint. Each orthogonal condition corresponds to a combination of the above three factors at different levels, and is used to carry out comparative analysis of the anti-fault performance of the lining structure.

[0045] Step 4: Perform orthogonal range analysis and multi-factor sensitivity analysis on the structural response data of each group of orthogonal working conditions obtained in Step 3 to determine the optimal combination of key geometric parameters of the three-dimensional refined numerical model.

[0046] Orthogonal range analysis and multi-factor sensitivity analysis were performed on the structural response data under each group of orthogonal working conditions to obtain the sum of the indices K of each key geometric parameter under different structural response data. jm Mean and range R of the indicators jThe factors influencing the order of importance and the optimal combination of levels for single indicators are analyzed, and based on this, trend graphs are plotted showing the changes in the response data of each structure with the level values ​​of key geometric parameters, such as... Figure 8 (a) Figure 8 (b) and Figure 8 As shown in (c), Figure 8 (a) is a trend graph showing the variation of structural response data Y1 with the values ​​of key geometric parameters. Figure 8 (b) is a trend graph showing the variation of structural response data Y2 with the values ​​of key geometric parameters. Figure 8 (c) is a trend graph showing the variation of structural response data Y3 with the levels of key geometric parameters. Figure 8 (a) Figure 8 (b) and Figure 8 (c) Analysis shows that the range of geometric parameter B, namely the length of the ductile short lining segment, is greater than that of geometric parameters A and C under structural response data Y1, Y2 and Y3. This indicates that the length of the ductile short lining segment is the dominant geometric parameter affecting the anti-fracture performance of the lining structure. The influence of geometric parameters A and C on different evaluation indicators differs in degree, but their overall influence is lower than that of geometric parameter B.

[0047] Based on the principle of single-index optimization, the target level combination of key geometric parameters corresponding to each structural response data is determined. First, a comparison is made for structural response data Y1, Y2, and Y3 respectively. For structural response data Y1 and Y2, since the mean values ​​of the indices corresponding to geometric parameters A, B, and C at levels 1, 2, and 3 respectively are relatively small, the target level combination of the key geometric parameters for both structural response data Y1 and Y2 is A1B3C1. For structural response data Y3, since the mean values ​​of the indices corresponding to geometric parameters A, B, and C at levels 1, 2, and 3 respectively are relatively small, the target level combination of the key geometric parameters for structural response data Y3 is A2B3C1.

[0048] To ensure consistency of the target levels for the same key geometric parameter across different structural response data: In all structural response data, the target level for geometric parameter B is level 3, and the target level for geometric parameter C is level 1. Therefore, level 3 for geometric parameter B and level 1 for geometric parameter C are determined as their respective comprehensive selected levels. Structural response data Y1 and Y2 correspond to target level 1 for geometric parameter A, while structural response data Y3 corresponds to target level 2 for geometric parameter A, creating a conflict. Therefore, additional comparative analysis of level 1 and level 2 for geometric parameter A is required: level 1 for geometric parameter A is selected as... Compared to the baseline, when the geometric parameter A changes from the first level to the second level (the length of the concrete lining segment increases from 6m to 8m), the structural response data Y3 (peak value of cross-sectional compressive deformation in the x-direction) only decreases by 0.33%. Since there is no increase, the deterioration of the second level of the structural response data Y3 is 0. However, the structural response data Y1 (peak value of damage volume index) increases by 27%, so the deterioration of the second level of the structural response data Y1 is 27. The structural response data Y2 (peak value of maximum shear strain) increases by 24%, so the deterioration of the second level of the structural response data Y2 is 24. The total deterioration of the second level is 24 + 27 = 51. Since the deterioration of geometric parameter A relative to its own structural response data at the first level is 0, the total deterioration of geometric parameter A at the first level is 0. Since the total deterioration of geometric parameter A at the first level is less than that at the second level, the first level is determined as the comprehensive selected level. The target level combination of the key geometric parameters of the three-dimensional refined numerical model is A1B3C1, that is, the length of the concrete lining segment is 6m, the length of the ductile short sub-lining segment is 3m, and the width of the flexible narrow joint is 2cm.

[0049] To verify the anti-fault performance of the lining structure obtained by the design method of this invention, the target level combination A1B3C1 of the key geometric parameters of the three-dimensional refined numerical model determined in step 4 was substituted into the three-dimensional refined numerical model. Under the same boundary conditions and load sequence, quantitative comparisons were made with the "no-fortification scheme" and the "traditional 6m conventional segment + 5cm wide joint scheme". The "no-fortification scheme" refers to the absence of ductile short lining segments and flexible narrow joints, with only concrete lining segments, i.e., the values ​​of B and C are both 0. The "traditional 6m conventional segment + 5cm wide joint scheme" refers to the absence of ductile short lining segments, with the concrete lining segment value being 6m and the spacing between concrete lining segments being 5cm, i.e., A=6m, B=0, C=5cm.

[0050] Under the coupled effect of 30cm displacement and 2MPa internal water pressure, the comparative results show that, Figure 9As shown, the peak value of the compressive deformation Y3 in the x-direction is reduced by approximately 58.1% compared to the unprotected scheme, and by approximately 44.5% compared to the traditional wide-slot scheme; as Figure 10 As shown, the peak volumetric damage index Y1 of the present invention is reduced by approximately 58.7% compared to the unprotected scheme and by approximately 45.1% compared to the traditional wide-slit scheme; as Figure 11 As shown, the maximum shear strain peak value Y2 of the present invention is reduced by about 76% compared with the unprotected scheme and by about 47.8% compared with the traditional wide-slit scheme.

[0051] The above comparison results fully verify the safety, economy, and engineering feasibility of the target level combination of key geometric parameters of the three-dimensional refined numerical model determined by the design method of this invention under the coupled action of complex geology and high internal water pressure.

[0052] The above embodiments are merely preferred embodiments of the present invention. Those skilled in the art can make equivalent substitutions or adaptive modifications to the specific arrangement of the lining segments, the mix proportion parameters of the high-ductility concrete, the values ​​of the geometric dimensions of each component, and the lining safety evaluation indicators and verification standards without departing from the principles and spirit of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

[0053] It should be noted that the specific embodiments described in this invention are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains can make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A hydraulic tunnel lining structure based on ductile short segments, comprising annular concrete lining segments (1), characterized in that, It also includes annular ductile short sub-lining segments (2), with concrete lining segments (1) and ductile short sub-lining segments (2) alternately arranged along the tunnel axis. Annular flexible narrow joints (3) are provided between adjacent concrete lining segments (1) and ductile short sub-lining segments (2). The flexible narrow joints (3) are filled with annular flexible fillers (6). Two annular two-layer cloth and one-layer membrane (4) and annular water-stopping structure (5) are arranged in the flexible narrow joints (3) along the lining thickness direction and are wrapped around the flexible fillers (6). The water-stopping structure (5) is located between the two layers of two-layer cloth and one-layer membrane (4). The two ends of the water-stopping structure (5) and the two-layer cloth and one-layer membrane (4) are anchored to the concrete lining segment (1) and the ductile short sub-lining segment (2), respectively.

2. The hydraulic tunnel lining structure based on ductile short segments according to claim 1, characterized in that, The concrete lining segment (1) is made of concrete with a strength grade of not less than C30, and the ductile short sub-lining segment (2) is made of high ductile concrete.

3. The hydraulic tunnel lining structure based on ductile short segments according to claim 2, characterized in that, The mechanical parameters of the high-ductility concrete at a curing age of 28 days are as follows: compressive strength greater than or equal to 25 MPa and less than or equal to 40 MPa, elastic modulus less than or equal to 20 GPa, ultimate tensile strain greater than or equal to 1%, and crack width less than or equal to 100 μm when the ultimate bearing capacity is reached.

4. The hydraulic tunnel lining structure based on ductile short segments according to claim 1, characterized in that, The water-stopping structure (5) is a W-type copper water-stopping strip.

5. A hydraulic tunnel lining structure based on ductile short segments according to claim 1, characterized in that, The flexible packing (6) is a GB flexible packing.

6. A design method for a hydraulic tunnel lining structure based on ductile short segments, applicable to the hydraulic tunnel lining structure based on ductile short segments as described in claim 1, characterized in that, Includes the following steps: Step 1: Obtain the basic design parameters and site survey parameters of the target tunnel project; Step 2: Determine the key geometric parameters for structural optimization design and select structural response data as the evaluation index for anti-fracture performance; Step 3: Determine the corresponding horizontal values ​​of the key geometric parameters and establish an orthogonal test scheme. Based on the basic design parameters and site survey parameters, construct a three-dimensional refined numerical model. Adjust the key geometric parameters in the three-dimensional refined numerical model according to the orthogonal test scheme and perform simulation calculations to obtain the structural response data of each group of orthogonal working conditions. Step 4: Perform orthogonal range analysis and multi-factor sensitivity analysis on the structural response data under each group of orthogonal working conditions to obtain the target level combination of key geometric parameters of the three-dimensional refined numerical model.

7. The design method for a hydraulic tunnel lining structure based on ductile short segments according to claim 6, characterized in that, The basic design parameters include the tunnel excavation inner diameter, lining thickness, maximum horizontal displacement for protection, and maximum internal water pressure for design. The site investigation parameters include the type of fault the target tunnel crosses, fault orientation, surrounding rock physical and mechanical parameters, and initial geostress field characteristics.

8. The design method for a hydraulic tunnel lining structure based on ductile short segments according to claim 6, characterized in that, The key geometric parameters include geometric parameter A, geometric parameter B, and geometric parameter C. Geometric parameter A is the length of the concrete lining segment, geometric parameter B is the length of the ductile short sub-lining segment, and geometric parameter C is the width of the flexible narrow joint. The structural response data used as evaluation indicators for resistance to fracture include the peak value of the volumetric damage index Y1, the peak value of the maximum shear strain Y2, and the peak value of the x-axis compressive deformation Y3.

9. The design method for a hydraulic tunnel lining structure based on ductile short segments according to claim 8, characterized in that, The acquisition of structural response data under each group of orthogonal working conditions is based on the following steps: Determine the level values ​​corresponding to geometric parameters A, B, and C, using L9(3) 4 Orthogonal arrays were used to formulate orthogonal test schemes. Based on the basic design parameters and site survey parameters of the target tunnel project, a three-dimensional refined numerical model was established using finite element software. Geometric parameters A, B, and C in the three-dimensional refined numerical model were adjusted according to the orthogonal test scheme. Simulation calculations were performed according to the preset load step sequence to obtain the structural response data of each group of orthogonal working conditions. Among them, L9(3 4 The first three columns of the orthogonal array correspond to geometric parameters A, B, and C, respectively, while the fourth column is a blank column used for error estimation.

10. The design method for a hydraulic tunnel lining structure based on ductile short segments according to claim 8, characterized in that, The target level combination of key geometric parameters for obtaining the three-dimensional refined numerical model is based on the following steps: Orthogonal range analysis and multi-factor sensitivity analysis were performed on the structural response data under each group of orthogonal working conditions to obtain the sum of indices, mean values, ranges, and order of influence of factors for each key geometric parameter under different structural response data. A correspondence was also established between the structural response data and the level values ​​of the key geometric parameters. For each structural response data, the target level combination of the key geometric parameters corresponding to that data was obtained according to the principle of minimizing the mean value. The target level of the same key geometric parameter in each target level combination was extracted, and consistency judgment was performed: if the target level of a certain key geometric parameter is consistent across all structural response data, then that target level is determined as the comprehensive selected level for that key geometric parameter. If the target level of a certain key geometric parameter is inconsistent under different structural response data, a certain target level of the key geometric parameter under different structural response data is selected as the comparison benchmark. Each target level of the key geometric parameter is compared with the comparison benchmark. The increase of each structural response data during the comparison process is recorded as the deterioration of the structural response data at the corresponding target level. The sum of the deterioration of each structural response data at the target level is taken as the total deterioration of the target level. The target level with the smallest total deterioration is selected as the comprehensive selected level of the key geometric parameter. Finally, the comprehensive selected levels of each key geometric parameter are combined to obtain the target level combination of the key geometric parameters of the three-dimensional refined numerical model.

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