A method, system and terminal for determining a combined lining of a high-pressure water conveyance tunnel

Abstract

The application relates to the technical field of hydraulic structure structure design, and particularly discloses a method and system for determining a combined lining of a high-pressure water conveying tunnel and a terminal, wherein, in the process of establishing a numerical calculation model of the combined lining, a composite drainage plate is equivalent to a uniform isotropic solid medium with a thickness of d, and a comprehensive elastic modulus E is adopted to represent the mechanical properties of the composite drainage plate; the structural stress of the composite drainage plate and the bearing ratio of the water pressure in the steel pipe are constrained by a steel pipe allowable stress control threshold, a pipe piece anti-cracking allowable stress control threshold and a steel pipe bearing ratio control threshold; and finally, the d / E value range of the composite drainage plate is determined. In this way, scientific and definite basis is provided for the value selection of the composite drainage d / E in the combined lining, the value selection problem at the present stage is solved, and the subjectivity of artificial selection is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic structure design, and more specifically, to a method and system for determining a combined lining of a high-pressure water conveying tunnel, and a terminal. BACKGROUND

[0002] With the continuous progress of water diversion engineering technology, water conveying tunnels are developing towards large HD values (the product of the internal water head H and the tunnel internal diameter D). Long-distance water conveying tunnels are facing increasingly complex environmental challenges.

[0003] Generally speaking, water conveying tunnels passing through core urban areas are not allowed to exchange water between the inside and outside of the tunnel to prevent pollution of the water supply. Single-pipe lining cannot meet the needs of high-pressure water conveying tunnels passing through urban areas.

[0004] To this end, researchers have proposed introducing a steel pipe inside the pipe lining to prevent water exchange between the inside and outside of the tunnel. In order to maximize the material properties of the steel pipe, a certain range of composite drainage board soft cushion is laid on the inner wall of the pipe lining to separate the inner and outer linings and increase the internal water pressure bearing ratio of the steel pipe. In order to enhance the stability of the steel pipe against external pressure, self-compacting concrete is filled between the steel pipe lining and the pipe lining to form a combined lining structure of the high-pressure water conveying tunnel.

[0005] Currently, for the combined lining structure of the high-pressure water conveying tunnel, researchers have proposed the design concept that the inner lining steel pipe and the outer lining pipe piece bear the internal water pressure and the external water and soil pressure, respectively, and this is achieved by laying a certain range of composite drainage board on the inner wall of the pipe lining.

[0006] However, when designing the composite drainage board, the elastic modulus of the cushion of the existing prestressed composite lining structure in the tunnel engineering is simply analogized. However, there are essential differences in the bearing mechanism and design concept between the prestressed composite lining of such tunnel engineering and the combined lining.

[0007] Directly analogizing may result in the selection of the composite drainage board not being suitable for the actual application scenario, such as being unable to meet the actual demand for long-term and large-scale drainage, leaving a huge safety hazard for the project.

[0008] There is still no scientific and explicit design method for the composite drainage board of the combined lining. Based on this, a scientific and explicit method for determining the combined lining of the high-pressure water conveying tunnel is provided to determine the structure of the composite drainage board in the combined lining, avoiding the subjectivity of human selection, and having important significance for the design of the combined lining structure of the high-pressure water conveying tunnel passing through urban areas and prohibiting water exchange between the inside and outside of the tunnel. SUMMARY

[0009] The technical problem to be solved by the present application is to provide a method, system and terminal for determining a combined lining of a high-pressure water conveying tunnel.

[0010] The technical problem to be solved by the present application is solved by the following technical solutions:

[0011] In a first aspect, the present application provides a method for determining a combined lining of a high-pressure water conveying tunnel, comprising:

[0012] A numerical calculation model of the combined lining is established, wherein the composite drainage plate of the combined lining is equivalent to a uniform isotropic solid medium with a thickness d, and a comprehensive elastic modulus E is used to represent the mechanical properties of the composite drainage plate;

[0013] According to the numerical calculation model, the maximum steel pipe hoop stress and the maximum segment lining hoop stress of the composite drainage plate are extracted when different d / E are taken;

[0014] According to the numerical calculation model, the average value of the internal water pressure bearing ratio of the steel pipe is calculated when the composite drainage plate takes different d / E;

[0015] The maximum steel pipe hoop stress, the maximum segment lining hoop stress and the average value of the internal water pressure bearing ratio of the steel pipe are respectively associated with the d / E value of the composite drainage plate, and a constraint expression is obtained based on the allowable stress control threshold of the steel pipe, the allowable stress control threshold of the segment and the bearing ratio control threshold of the steel pipe;

[0016] The constraint expression is solved to obtain the d / E value range of the composite drainage plate to guide the structure design of the combined lining of the high-pressure water conveying tunnel.

[0017] Further, the numerical calculation model of the combined lining is established, wherein the composite drainage plate of the combined lining is equivalent to a uniform isotropic solid medium with a thickness d, and a comprehensive elastic modulus E is used to represent the mechanical properties of the composite drainage plate, comprising:

[0018] The comprehensive elastic modulus E of the composite drainage plate is determined using the following formula:

[0019]

[0020] Wherein, d is the thickness of the composite drainage plate, S is the bottom area of the composite drainage plate, F is the concentrated force for extruding the composite drainage plate, and Δu represents the compression amount of the composite drainage plate under the action of the concentrated force.

[0021] Further, according to the numerical calculation model, the average value of the internal water pressure bearing ratio of the steel pipe is calculated when the composite drainage plate takes different d / E, including:

[0022] The laying range of the composite drainage plate is determined, and the cross section of a steel pipe is selected every predetermined interval in the laying range to calculate the steel pipe bearing ratio, and a plurality of steel pipe cross section bearing ratios are obtained;

[0023] The average value of the plurality of steel pipe cross section bearing ratios is taken as the average value of the internal water pressure bearing ratio of the steel pipe under the current d / E value.

[0024] Further, the laying range of the composite drainage plate is determined, and the cross section of a steel pipe is selected every predetermined interval in the laying range to calculate the steel pipe bearing ratio, and a plurality of steel pipe cross section bearing ratios are obtained, including:

[0025] The cross section of a steel pipe is selected every 1° in the laying range to calculate the steel pipe bearing ratio, and a plurality of steel pipe cross section bearing ratios are obtained.

[0026] Further, the cross section of a steel pipe is selected every 1° in the laying range to calculate the steel pipe bearing ratio, and a plurality of steel pipe cross section bearing ratios are obtained, including:

[0027] The cross section of a steel pipe is selected every 1° in the laying range to calculate the steel pipe bearing ratio according to the following formula:

[0028]

[0029] Wherein, n is the angle value of the laying range of the composite drainage plate, N i is the axial force calculation value of the i-th cross section of the steel pipe under the design internal water pressure P, η i is the steel pipe cross section bearing ratio of the i-th cross section of the steel pipe under the design internal water pressure P, R is the inner radius of the combined lining, and b is the width of the single ring segment.

[0030] Further, the maximum value of the steel pipe hoop stress, the maximum value of the segment lining hoop stress, and the average value of the internal water pressure bearing ratio of the steel pipe are respectively associated with the d / E value corresponding to the composite drainage plate, and the constraint expression is obtained based on the allowable stress control threshold of the steel pipe, the allowable stress control threshold of the segment, and the bearing ratio control threshold of the steel pipe, including:

[0031] The maximum value of the steel pipe hoop stress under different d / E value schemes of the composite drainage plate is taken, and the maximum value of the steel pipe hoop stress and the corresponding d / E value are associated with the following formula by using curve fitting:

[0032]

[0033] Wherein, A is the numerical value of the maximum hoop stress of the steel pipe, x is the numerical value of d / E, a, b, c, B, C are constants, B and C are negative values, a, b, and c are positive values, and e is a natural constant.

[0034] Further, the maximum hoop stress of the steel pipe, the maximum hoop stress of the pipe lining, and the average value of the internal water pressure bearing ratio of the steel pipe are respectively associated with the d / E value of the composite drainage plate, and constraint expressions are obtained based on the allowable stress control threshold of the steel pipe, the anti-cracking allowable stress control threshold of the pipe lining, and the bearing ratio control threshold of the steel pipe, including:

[0035] The maximum hoop stress of the pipe lining under different d / E value schemes of the composite drainage plate is taken, and the maximum hoop stress of the pipe lining and the corresponding d / E value are associated with each other by curve fitting according to the following formula:

[0036]

[0037] Wherein, D is the numerical value of the maximum hoop stress of the pipe lining, x is the numerical value of d / E, g, f, and F are constants, and are all positive values, and e is a natural constant.

[0038] Further, the maximum hoop stress of the steel pipe, the maximum hoop stress of the pipe lining, and the average value of the internal water pressure bearing ratio of the steel pipe are respectively associated with the d / E value of the composite drainage plate, and constraint expressions are obtained based on the allowable stress control threshold of the steel pipe, the anti-cracking allowable stress control threshold of the pipe lining, and the bearing ratio control threshold of the steel pipe, including:

[0039] The average value of the internal water pressure bearing ratio of the steel pipe under different d / E value schemes of the composite drainage plate is taken, and the average value of the internal water pressure bearing ratio of the steel pipe and the corresponding d / E value are associated with each other by curve fitting according to the following formula:

[0040]

[0041] Wherein, Y is 100 times the average value of the internal water pressure bearing ratio of the steel pipe, x is the numerical value of d / E, m, n, y, M, and N are constants, M and N are negative values, m, n, and y are positive values, and e is a natural constant.

[0042] In a second aspect, the application further provides a determination system of the combined lining of the high-pressure water conveying tunnel, which operates according to the above method.

[0043] In a third aspect, the application further provides a terminal, which comprises a processor coupled with a memory and reading and executing instructions stored in the memory; when the processor executes the instructions, the processor is used to execute the determination method of the combined lining of the high-pressure water conveying tunnel.

[0044] In summary, the present application includes at least one of the following beneficial technical effects:

[0045] In the numerical calculation model of the combined lining, the composite drainage plate is equivalent to a uniform isotropic solid medium with a thickness of d, and the comprehensive elastic modulus E is used to represent the mechanical properties of the composite drainage plate, thereby grasping the most essential mechanical characteristics of the composite drainage plate, realizing the computability of the complex structure, and providing a premise for analyzing the mechanical behavior of the composite drainage plate.

[0046] According to the numerical calculation model, the maximum circumferential stress of the steel pipe and the maximum circumferential stress of the pipe lining are extracted when the composite drainage plate takes different d / E, and the average value of the internal water pressure bearing ratio of the steel pipe is calculated, so as to accurately capture the core parameters that can reflect the safety state of the structure.

[0047] The maximum circumferential stress of the steel pipe, the maximum circumferential stress of the pipe lining, and the average value of the internal water pressure bearing ratio of the steel pipe are respectively associated with the d / E value of the composite drainage plate, and the constraint expression is obtained based on the allowable stress control threshold of the steel pipe, the allowable stress control threshold of the pipe lining, and the bearing ratio control threshold of the steel pipe. Thus, the integration of multi-objective constraints is realized by mathematical method.

[0048] The value range of the d / E of the composite drainage plate is determined, which provides a scientific and clear basis for the value of the d / E of the composite drainage plate in the combined lining, solves the problem of relying on experience for value selection at the present stage, and avoids the subjectivity of human selection.

[0049] Based on the d / E of the composite drainage plate, the internal water pressure bearing ratio of the steel pipe lining can be adjusted and controlled, which can make the steel pipe lining bear as much internal water pressure as possible on the basis of ensuring the safety of the lining structure, so as to fully exert the bearing performance of the steel pipe material, and at the same time avoid the cracking of the outer lining pipe. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 It is a flowchart of the determination method of the combined lining of the high-pressure water conveying tunnel.

[0051] Figure 2 It is a schematic diagram of the combined lining structure.

[0052] Figure 3 It is a schematic diagram of the equivalent calculation of the comprehensive elastic modulus of the composite drainage plate.

[0053] Figure 4 It is a schematic diagram of the numerical calculation model of the combined lining.

[0054] Figure 5 It is a specific structure diagram of the composite drainage plate in the embodiment of the present application.

[0055] Figure 6A correlation diagram of the maximum hoop stress of the steel pipe and the d / E value of the composite drainage plate in the embodiment of the present application;

[0056] Figure 7 A correlation diagram of the maximum hoop stress of the pipe lining and the d / E value of the composite drainage plate in the embodiment of the present application;

[0057] Figure 8 A correlation diagram of the average internal water pressure bearing ratio of the steel pipe and the d / E value of the composite drainage plate in the embodiment of the present application. DETAILED DESCRIPTION

[0058] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the present application will be further described below in combination with specific drawings.

[0059] Embodiment 1

[0060] As shown in the drawings, Figure 1 The present application discloses a determination method of a combined lining of a high-pressure water conveying tunnel, which first establishes a numerical calculation model of the combined lining to realize the computability of the complex structure and provide a premise for accurately analyzing the mechanical behavior in the combined lining structure.

[0061] In the numerical calculation model, the composite drainage plate of the combined lining is equivalent to a uniform isotropic solid medium with a thickness of d, and the comprehensive elastic modulus E is used to represent the mechanical properties of the composite drainage plate. In this way, the most essential mechanical characteristics of the composite drainage plate are grasped, and the engineering design problem is converted into a constraint and optimization problem of key parameters.

[0062] Subsequently, according to the numerical calculation model, the maximum hoop stress of the steel pipe and the maximum hoop stress of the pipe lining of the composite drainage plate are extracted when the d / E value is different, and the average internal water pressure bearing ratio of the steel pipe is calculated to accurately capture the core parameters that can reflect the safety state of the structure.

[0063] Then, the maximum hoop stress of the steel pipe, the maximum hoop stress of the pipe lining, and the average internal water pressure bearing ratio of the steel pipe are respectively associated with the d / E value of the composite drainage plate, and constraint expressions are obtained based on the allowable stress control threshold of the steel pipe, the allowable stress control threshold of the pipe lining, and the bearing ratio control threshold of the steel pipe. In this way, the multiple objective constraints are integrated by converting them into constraint expressions through mathematical methods.

[0064] Finally, the constraint expressions are solved to obtain the d / E value range of the composite drainage plate to guide the structural design of the combined lining of the high-pressure water conveying tunnel.

[0065] Specifically, the structure of the combined lining of the water conveying tunnel is as shown in the drawings, Figure 2As shown, due to the complex geometry of the composite drainage board, it is difficult to accurately simulate it in the overall finite element model.

[0066] In the overall structural analysis of the lining of high-pressure water conveyance tunnels, the core objective is to study the macroscopic mechanical response of the lining system, such as stress distribution, deformation, and overall stability. In this type of mechanical analysis, the core function of the composite drainage board is to transmit compressive stress and undergo compressive deformation.

[0067] Therefore, in the technical solution of this application, the composite drainage board is equivalent to a uniform isotropic solid medium with a thickness of d, and the comprehensive elastic modulus E is used to characterize the mechanical properties of the composite drainage board.

[0068] like Figure 3 As shown, the composite drainage board is compressed by two rigid plates, and the compression amount Δu (mm) under the action of a concentrated force F (N) is obtained. Then, the comprehensive elastic modulus E (MPa) of the composite drainage board is:

[0069]

[0070] Where d is the thickness of the composite drainage board (mm); S is the bottom area of ​​the composite drainage board (mm²). 2 ).

[0071] After obtaining the comprehensive elastic modulus E of the composite drainage board, the d / E (mm) of the composite drainage board can be obtained. 3 The value of / N) can be obtained by changing the value of d or E to achieve different d / E values.

[0072] It is worth mentioning that the composite drainage board d / E in the technical solution of this application can characterize the compressive deformation capacity of the composite drainage board per unit area under unit pressure, that is, it can characterize the force transmission capacity of the composite drainage board to a certain extent.

[0073] The inner radius of the composite lining structure is R (m), and the width of a single ring segment b (m) is taken in the tunnel axis for analysis. Then, based on the specific structural dimensions of the composite lining, a three-dimensional finite element cracking calculation model is established.

[0074] like Figure 4 As shown, in this calculation model, the pea gravel, pipe segments, self-compacting concrete, and composite drainage board are all simulated using three-dimensional solid elements (C3D8R); the steel pipes and stiffening rings (reinforcing rings) are simulated using three-dimensional shell elements (S4R); and the bolts are simulated using embedded rod elements (T3D2), with the rod elements completely embedded in the pipe segment elements without slippage.

[0075] In addition, the face-to-face contact unit is used to simulate the interfaces between the pipe segment and the pea gravel, between the pipe segment and the self-compacting concrete and the composite drainage plate, between the steel pipe and the self-compacting concrete, and between the pipe segments. The interface between the composite drainage plate and the self-compacting concrete shares a node.

[0076] Under the action of internal water pressure, the constraint of surrounding rock on the outward deformation of the lining structure is characterized by a ground spring. Except that the self-compacting concrete constitutive model uses a concrete plastic damage model, the constitutive models of the remaining materials all use linear elastic models. The load only considers the action of internal water pressure and is applied to the inner surface of the steel pipe. According to the established numerical calculation model, the internal water pressure P (MPa) loading numerical calculation of the composite drainage plate with different d / E values is carried out.

[0077] Then, the maximum stress of the lining structure is extracted, and the steel pipe bearing ratio is calculated.

[0078] Specifically, the maximum circumferential stress of the steel pipe σ slmax (MPa) and the maximum circumferential stress of the pipe segment lining σ cmax (MPa) in the lining structure under the action of the design internal water pressure (internal water pressure) P of the composite drainage plate with different d / E values are extracted. slmax It is worth mentioning that the maximum circumferential stress of the steel pipe σ cmax and the maximum circumferential stress of the pipe segment lining σ i can be directly extracted from the numerical calculation model.

[0079] Under each d / E value scheme, the bearing ratio of each section of the steel pipe within the laying range of the composite drainage plate is calculated using the following formula:

[0080]

[0081] Wherein, n is the angle value of the laying range of the composite drainage plate, that is, every 1° within the laying range of the composite drainage plate, a section is selected for steel pipe bearing ratio calculation; N i is the calculated value of the axial force (MN) of the i-th section of the steel pipe under the action of the design internal water pressure P; η i is the bearing ratio of the i-th section of the steel pipe under the action of the design internal water pressure P; R is the inner radius of the combined lining structure. And the average value of the bearing ratio of the steel pipe under each d / E value scheme is calculated using the following formula:

[0082]

[0083] Wherein, n is the angle value of the laying range of the composite drainage plate.

[0084] The allowable stress control threshold of the steel pipe, the allowable stress control threshold of the pipe segment, and the bearing ratio control threshold of the steel pipe are determined.

[0085] In one example, according to the Design Specification for Steel Penstock of Hydraulic and Hydro-Power Projects and the steel grade of the steel pipe, a steel pipe allowable stress control threshold [σ sl ] is determined; according to the Design Specification for Concrete Structures of Hydraulic Engineering and the concrete strength grade of the segment lining, a segment anti-cracking allowable stress control threshold [σ c ] is determined; and according to the design concept of realizing that the steel pipe lining bears most of the internal water pressure in the combined lining design, a steel pipe load ratio control threshold [η] is determined.

[0086] In this way, the maximum circumferential stress of the steel pipe, the maximum circumferential stress of the segment lining, and the average value of the internal water pressure load ratio of the steel pipe are respectively associated with the d / E value of the composite drainage plate.

[0087] Specifically, the maximum circumferential stress of the steel pipe σ slmax under different d / E value schemes of the composite drainage plate is taken, and the corresponding data points of the maximum circumferential stress of the steel pipe σ slmax and d / E are associated with the following formula by curve fitting:

[0088]

[0089] Wherein, A is the numerical value of the maximum circumferential stress of the steel pipe σ slmax ; x is the numerical value of d / E; a, b, c, B, C are constants, B and C are negative values, a, b and c are positive values, and e is the natural constant.

[0090] Here, the composite drainage plate plays a role of reducing the transmission of internal water pressure from the steel pipe to the external segment lining by its own compression deformation in the combined lining structure. The stress release of the composite drainage plate is significant when it is initially slightly compressed, and since the stress tends to be saturated, the composite exponential function can accurately capture this phenomenon. The function form is an ideal mathematical model for describing a physical process in which the response value first increases rapidly and then gradually saturates with the increase of the parameter.

[0091] The maximum circumferential stress of the segment lining σ cmax under different d / E value schemes of the composite drainage plate is taken, and the corresponding data points of the maximum circumferential stress of the segment lining σ cmax and d / E are associated with the following formula by curve fitting:

[0092]

[0093] Wherein, D is the numerical value of the maximum circumferential stress of the segment lining σ cmax ; x is the numerical value of d / E; g, f, and F are constants, and all are positive values.

[0094] Similarly, the pipe segment lining is the main structure to bear the external water and soil pressure, and the part of the internal water pressure transferred through the steel pipe and the cushion (composite drainage plate) is its additional load. The part of the internal water pressure stress transferred to the pipe segment lining will be nonlinearly reduced with the increase of d / E of the composite drainage plate. The function form effectively describes the negative correlation between the pipe segment stress and the increase of d / E of the composite drainage plate.

[0095] The average value of the internal water pressure bearing ratio of the steel pipe under different d / E value schemes of the composite drainage plate , and the data points corresponding to d / E are associated and expressed by the following formula through curve fitting:

[0096]

[0097] wherein Y is 100 ; x is the numerical value of d / E; m, n, y, M, and N are constants, M and N are negative values, and m, n, and y are positive values.

[0098] The internal water pressure bearing ratio directly measures the proportion of the steel pipe bearing the internal water pressure, and the formula can accurately depict the physical phenomenon of "bearing ratio growth saturation". Similar to the stress of the steel pipe, this improvement also has a "marginal effect". When the d / E value of the composite drainage plate reaches a certain value, it becomes more and more difficult for the steel pipe to improve the bearing ratio, that is, most of the internal water pressure is borne by the steel pipe.

[0099] Combined with the allowable stress control index of the steel pipe [σ sl ], the allowable stress control index of the pipe segment [σ c ], and the bearing ratio control index of the steel pipe [η], the maximum value of the circumferential stress of the steel pipe, the maximum value of the circumferential stress of the pipe segment lining, and the average value of the internal water pressure bearing ratio of the steel pipe are constrained, which can be expressed by the formula:

[0100]

[0101] Through solving, the first value range of d / E d / E≤x1(mm 3 / N) can be obtained from the above first formula; the second value range of d / E d / E≥x2(mm 3 / N) can be obtained from the above second formula; and the third value range of d / E d / E≥x3(mm 3 / N) can be obtained from the above third formula.

[0102] The intersection of the three value ranges is the d / E value range of the composite drainage plate that can meet the stress and steel pipe bearing ratio requirements of the combined lining structure. Finally, the reasonable d / E value range of the composite drainage plate is obtained as follows: (mm 3 / N).

[0103] Steel pipe allowable stress control index [σ sl ] constraint ensures the safety of the steel pipe, the pipe crack allowable stress control index [σ c ] constraint ensures that the concrete does not crack in the actual scene, and the steel pipe bearing ratio control index [η] constraint is a mathematical expression of the design concept to play the advantage of water resistance of the steel pipe.

[0104] By establishing the constraint expression, the three design goals are unified into a mathematical framework, scientifically quantifying "what mechanical properties (d / E value) the composite drainage plate should have on the premise of meeting all safety and use requirements", and fundamentally avoiding the risks brought by one-sided and subjective decisions relying on individual engineer's experience.

[0105] In this way, by curve fitting to establish a mathematical correlation between stress and bearing ratio and d / E, and based on multiple control thresholds to build a constraint expression, and finally by intersection to determine the reasonable range of d / E, the parameter optimization under multi-objective constraint is realized, ensuring the comprehensive performance of the structure in strength, crack resistance and functionality, and having strong engineering applicability and promotional value.

[0106] Example 2:

[0107] The calculation conditions are as follows:

[0108] In the combined lining of this embodiment, the outer lining segment lining is composed of one capping block (central angle of 15°), two adjacent blocks (central angle of 64.5°) and three standard blocks (central angle of 72°), the segment lining has an inner diameter of 5.8 m, a segment thickness of 30 cm, and an external pea gravel backfill grouting layer thickness of 15 cm; the inner lining steel pipe has an inner diameter of 5.2 m, a steel pipe wall calculation thickness of 16 mm, and a 30 cm thick C30 self-compacting concrete backfill between the inner lining steel pipe and the outer lining segment; the composite drainage plate is laid on the inner wall of the segment lining in a range of 240°, and the thickness d of the composite drainage plate is 15 mm, and the specific structural dimensions are shown in Figure 5 .

[0109] The inner water pressure borne by the tunnel design is P = 1.355 MPa, and the structure contained in the combined lining and the material parameters involved are shown in the following table, and the elastic resistance coefficient of the surrounding rock of the calculation section is 2866 MPa / m.

[0110]

[0111] Among them, the self-compacting concrete plastic damage model parameters are: ψ (shear dilatancy angle) = 30°, ϵ (flow potential offset) = 0.1, ĸ (invariant stress ratio) = 0.67, σ b0 / σ c0 (the ratio of biaxial ultimate compressive strength to uniaxial compressive ultimate strength) = 1.16, (viscosity coefficient) = 5 x 10 -4 .

[0112] Firstly, the calculation model is established, and numerical calculation is carried out.

[0113] The established three-dimensional finite element calculation model of the combined lining is shown in Figure 4 The thickness d of the composite drainage plate is 15 mm, and by changing the comprehensive elastic modulus E of the composite drainage plate, the numerical calculation results of the stress of the combined lining structure under different d / E values of the composite drainage plate are obtained.

[0114] Then, the stress of the lining structure is extracted, and the bearing ratio of the steel pipe is calculated.

[0115] According to the numerical calculation results of the stress of the lining structure in the above steps, the maximum hoop stress of the steel pipe and the pipe lining under different d / E values of the composite drainage plate is extracted; the axial force of the steel pipe cross section within the laying range of the composite drainage plate is extracted every 1°.

[0116] Based on this, the bearing ratio of the steel pipe at 240 cross sections within the laying range of the composite drainage plate (the laying range of the drainage plate is 240°, and one cross section is taken every 1°) is calculated, and then the average value of the steel pipe bearing ratio of the composite drainage plate under this d / E value scheme is further obtained, and the average value of the steel pipe bearing ratio of the composite drainage plate under different d / E values is obtained.

[0117] In this example, the maximum hoop stress of the steel pipe and the pipe lining, and the average value of the steel pipe bearing ratio of the composite drainage plate under different d / E value schemes are shown in the following table:

[0118]

[0119] Then, according to the "SLT281-2020 Design Code for Pressure Steel Pipes of Water Conservancy and Hydropower Engineering" and the steel grade Q345R of the steel pipe, the allowable stress control index [σ sl ] of the steel pipe is determined to be 190 MPa; according to the "NBT11011-2022 Design Code for Hydraulic Concrete Structures" and the concrete strength grade C55 of the pipe lining, the crack resistance allowable stress control index [σ c ] of the pipe lining is determined to be 1.51 MPa; and according to the design concept that the steel pipe lining bears most of the internal water pressure in the combined lining design, the steel pipe bearing ratio control index [η] is determined to be 70%.

[0120] Finally, the reasonable d / E value range of the composite drainage plate is determined.

[0121] The maximum hoop stress σ slmax of the steel pipe under different d / E value schemes of the composite drainage plate is taken, and the maximum hoop stress σ slmaxand d / E corresponding data points as shown in Figure 6 According to the allowable stress of the steel pipe [σ sl ]=190MPa, and combined with the relevant formula:

[0122]

[0123] After solving, the first range of d / E d / E≤x1(mm 3 / N) can be obtained, x1=45.1.

[0124] The maximum value of the ring stress of the pipe lining σ cmax , the maximum value of the ring stress of the pipe lining σ cmax and d / E corresponding data points as shown in Figure 7 According to the allowable stress of the steel pipe [σ c ]=1.51MPa, and combined with the relevant formula:

[0125]

[0126] After solving, the second range of d / E d / E≥x2(mm 3 / N) can be obtained, x2=6.5.

[0127] The average value of the internal water pressure bearing ratio of the steel pipe when taking different d / E value schemes of the composite drainage plate , the average value of the internal water pressure bearing ratio of the steel pipe when taking different d / E value schemes of the composite drainage plate Figure 8 According to the bearing ratio control index of the steel pipe [η]=70%, and combined with the relevant formula:

[0128]

[0129] After solving, the third range of d / E d / E≥x3(mm 3 / N) can be obtained, x3=12.4.

[0130] Taking the intersection of the three value ranges, the d / E value range of the composite drainage plate that can meet the stress and bearing ratio requirements of the combined lining structure is finally obtained as mm 3 / N.

[0131] The application also discloses a determination system of the combined lining of the high-pressure water conveying tunnel, which operates according to the determination method of the combined lining of the high-pressure water conveying tunnel.

[0132] The application further discloses a terminal, which comprises a processor coupled with a memory and reading and executing instructions stored in the memory; when the processor executes the instructions, the processor is used to execute the determination method of the combined lining of the high-pressure water conveying tunnel.

[0133] The memory can be an internal storage unit of the terminal in some embodiments, such as a hard disk or a memory of the terminal.

[0134] The memory can also be an external storage device of the terminal in other embodiments, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc.

[0135] Further, the memory can include both an internal storage unit and an external storage device of the terminal.

[0136] The memory is used to store application software and various data installed on the terminal, such as program codes installed on the terminal, etc.

[0137] The memory can also be used to temporarily store data that has been output or will be output. In an embodiment, the memory stores instructions that can be executed by the processor to perform the method for determining the combined lining of a high-pressure water conveyance tunnel.

[0138] The processor can be a central processing unit (CPU), a microprocessor or other data processing chip in some embodiments, used to run instructions stored in the memory or process data, such as to perform the method for determining the combined lining of a high-pressure water conveyance tunnel, etc.

[0139] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above embodiments, and various changes and improvements can be made without departing from the spirit and scope of the present application. These changes and improvements all fall within the scope of the present application. The scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for determining the composite lining of a high-pressure water conveyance tunnel, characterized in that, include: A numerical calculation model for the composite lining is established, wherein the composite drainage board of the composite lining is equivalent to a uniform isotropic solid medium with a thickness of d, and the comprehensive elastic modulus E is used to characterize the mechanical properties of the composite drainage board. Based on the numerical calculation model, the maximum circumferential stress of the steel pipe and the maximum circumferential stress of the pipe lining are extracted when the composite drainage board takes different d / E values. Based on the numerical calculation model, the average value of the internal water pressure bearing ratio of the steel pipe when the composite drainage board takes different d / E values ​​is calculated. The maximum circumferential stress of the steel pipe, the maximum circumferential stress of the lining segment, and the average internal water pressure bearing ratio of the steel pipe are respectively correlated with the d / E value corresponding to the composite drainage board. Constraint expressions are obtained based on the allowable stress control threshold of the steel pipe, the allowable stress control threshold of the lining segment, and the bearing ratio control threshold of the steel pipe. Solving the constraint expression yields the range of d / E values ​​for the composite drainage board, which guides the structural design of the combined lining of high-pressure water conveyance tunnels. The numerical calculation model for the composite lining is a three-dimensional finite element cracking calculation model. In the three-dimensional finite element cracking calculation model: Under the action of internal water pressure, the constraint of the surrounding rock on the outward deformation of the lining structure is characterized by grounding springs; except for the self-compacting concrete constitutive model which adopts the concrete plastic damage model, the constitutive models of the other materials are all adopted by linear elastic models; the load only considers the effect of internal water pressure and is applied to the inner surface of the steel pipe.

2. The method for determining the composite lining of a high-pressure water conveyance tunnel according to claim 1, characterized in that, A numerical calculation model for the composite lining is established, wherein the composite drainage board of the composite lining is equivalent to a homogeneous isotropic solid medium of thickness d, and the comprehensive elastic modulus E is used to characterize the mechanical properties of the composite drainage board, including: The overall elastic modulus E of the composite drainage board is determined using the following formula: Wherein, d is the thickness of the composite drainage board, S is the bottom area of ​​the composite drainage board, F is the concentrated force that compresses the composite drainage board, and Δu represents the amount of compression of the composite drainage board under the action of the concentrated force.

3. The method for determining the composite lining of a high-pressure water conveyance tunnel according to claim 1, characterized in that, Based on the numerical calculation model, the average internal water pressure bearing ratio of the steel pipe for different d / E values ​​of the composite drainage board is calculated, including: The laying range of the composite drainage board is determined. Within the laying range, the cross section of the steel pipe is selected at predetermined intervals to calculate the bearing ratio of the steel pipe, thereby obtaining multiple bearing ratios of the steel pipe cross sections. The average value of the bearing capacity ratio of the multiple steel pipe sections is taken as the average value of the internal water pressure bearing capacity ratio of the steel pipe under the current d / E value.

4. The method for determining the composite lining of a high-pressure water conveyance tunnel according to claim 3, characterized in that, The laying range of the composite drainage board is determined. Within the laying range, the cross-section of the steel pipe is selected at predetermined intervals to calculate the bearing ratio of the steel pipe, resulting in multiple bearing ratios of the steel pipe cross-sections, including: Within the laying range, the cross-section of the steel pipe is selected at 1° intervals to calculate the bearing ratio of the steel pipe, thereby obtaining the bearing ratio of the multiple steel pipe cross-sections.

5. The method for determining the composite lining of a high-pressure water conveyance tunnel according to claim 4, characterized in that, Within the laying range, the load-bearing ratio of the steel pipe is calculated by selecting a cross-section of the steel pipe at 1° intervals, resulting in the load-bearing ratios of the plurality of steel pipe cross-sections, including: Within the laying range, a cross-section of the steel pipe is selected at 1° intervals, and the load-bearing ratio of the steel pipe is calculated using the following formula: Where n is the angle value of the composite drainage board laying range, N i To calculate the axial force at the i-th section of the steel pipe under the action of internal water pressure P, η i The bearing capacity ratio of the steel pipe section at the i-th section under the action of internal water pressure P is given by R, where R is the inner radius of the composite lining and b is the width of the single-ring segment.

6. The method for determining the composite lining of a high-pressure water conveyance tunnel according to claim 1, characterized in that, The maximum circumferential stress of the steel pipe, the maximum circumferential stress of the lining segments, and the average internal water pressure bearing ratio of the steel pipe are respectively correlated with the d / E value corresponding to the composite drainage board. Based on the allowable stress control threshold of the steel pipe, the allowable stress control threshold for crack resistance of the lining segments, and the bearing ratio control threshold of the steel pipe, constraint expressions are obtained, including: The maximum circumferential stress of the steel pipe under different d / E values ​​of the composite drainage board is taken, and the maximum circumferential stress of the steel pipe and the corresponding d / E value are expressed by curve fitting using the following formula: Where A is the maximum value of the circumferential stress of the steel pipe, x is the value of d / E, a, b, c, B, and C are constants, B and C are negative values, a, b, and c are positive values, and e is a natural constant.

7. The method for determining the composite lining of a high-pressure water conveyance tunnel according to claim 1, characterized in that, The maximum circumferential stress of the steel pipe, the maximum circumferential stress of the lining segments, and the average internal water pressure bearing ratio of the steel pipe are respectively correlated with the d / E value corresponding to the composite drainage board. Based on the allowable stress control threshold of the steel pipe, the allowable stress control threshold for crack resistance of the lining segments, and the bearing ratio control threshold of the steel pipe, constraint expressions are obtained, including: The maximum circumferential stress of the pipe lining under different d / E values ​​of the composite drainage board is taken, and the maximum circumferential stress of the pipe lining and the corresponding d / E value are expressed by curve fitting using the following formula: Where D is the maximum value of the circumferential stress of the segment lining, x is the value of d / E, g, f, and F are constants, all of which are positive, and e is a natural constant.

8. The method for determining the composite lining of a high-pressure water conveyance tunnel according to claim 1, characterized in that, The maximum circumferential stress of the steel pipe, the maximum circumferential stress of the lining segments, and the average internal water pressure bearing ratio of the steel pipe are respectively correlated with the d / E value corresponding to the composite drainage board. Based on the allowable stress control threshold of the steel pipe, the allowable stress control threshold for crack resistance of the lining segments, and the bearing ratio control threshold of the steel pipe, constraint expressions are obtained, including: The average internal water pressure bearing ratio of the steel pipe under different d / E values ​​of the composite drainage board is taken, and the average internal water pressure bearing ratio of the steel pipe and the corresponding d / E value are expressed by curve fitting using the following formula: Where Y is 100 times the average value of the internal water pressure bearing ratio of the steel pipe, x is the value of d / E, m, n, y, M, and N are constants, M and N are negative values, m, n, and y are positive values, and e is a natural constant.

9. A system for determining the composite lining of a high-pressure water conveyance tunnel, characterized in that, Operate as described in any one of claims 1-8 above.

10. A terminal, characterized in that, include: A processor for coupling with memory and for reading and executing instructions stored in said memory; When the processor is running, it executes the instructions, causing the processor to perform the method for determining the combined lining of a high-pressure water conveyance tunnel as described in any one of claims 1-8.

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