A segmented rigidity collaborative design method for an underwater suspended tunnel

Abstract

The application discloses a segmented rigidity coordination design method for an underwater suspended tunnel and relates to the technical field of civil engineering. The method disclosed by the application fills the technical blank of the rigidity design of the underwater suspended tunnel structure, promotes the development of the underwater suspended tunnel, provides a more controllable and more universal design method, and solves the problem that the joint structure of the suspended tunnel is not researched and designed by anyone at the present stage. The joint rigidity design is a brand-new design concept. The anchor cable rigidity design method in the application adopts an innovative segmented method, decouples the coupling effect between multiple pipe sections, and achieves good effect after design, and generates a better structure response and a moderated displacement curve compared with the existing pre-tightening force optimization design. In addition, the method can also be used for cable adjustment of a cable-stayed bridge, also adopts a segmented method, and finally, according to the stress and displacement requirements of each section, the vertical rigidity of each cable is designed to obtain the total rigidity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of civil engineering, in particular to a segmented stiffness collaborative design method for an underwater suspended tunnel. BACKGROUND

[0002] The underwater suspended tunnel (SFT) is a competitive structure for crossing deep straits, complex seabed geological conditions, and complex navigation conditions. It has strong concealment, high stability, and stable stress, but it is highly dependent on hydrogeological conditions. Deep straits or too bumpy geological conditions will greatly affect the construction difficulty. For an overwater sea-crossing bridge, it has mature construction technology, safe driving, and high ornamental value, but it is highly sensitive to the operating environment. In high sea waves, complex navigation requirements, and high wind load, it will have a greater impact on the safety of the structure.

[0003] After the concept of the underwater suspended tunnel was proposed, there were gradually some idealized designs, research on external load types, research on pipe section forms and wave load, and research on various detailed structures. After years of exploration, the research on external structures has become mature, and scholars have gradually shifted their research direction from the outside to the inside, from research to design. They have studied the stress characteristics of the inner wall of the underwater suspended tunnel, the dynamic response of the tunnel structure in the event of an accident, the design of the underwater breakwater of the underwater suspended tunnel, the working state of the joint structure of the suspended tunnel, the seismic performance of the underwater suspended tunnel including the mechanical properties of the joint, and the influence of the stiffness change of the joint structure on the dynamic response of the tunnel pipe under wave action.

[0004] From the existing research results, it can be seen that the pipe stiffness, joint stiffness, and anchor stiffness of the underwater suspended tunnel have a great influence on its dynamic response and safety and comfort of traffic. Studies have shown that under appropriate anchor pre-tensioning conditions (i.e., different initial stiffness of anchor configuration conditions), uniform internal forces can be generated to achieve full utilization of materials and obtain a more moderate structure displacement curve. Under appropriate joint stiffness, higher comfort and higher economy can be achieved.

[0005] Therefore, a reasonable pipe stiffness, anchor stiffness, and joint stiffness design method is the key to the safety and comfort of the underwater suspended tunnel. However, there is currently no research on the configuration of joint structure stiffness, anchor stiffness, and pipe stiffness.

[0006] Therefore, a new solution is needed to solve the above problems. SUMMARY

[0007] The purpose of the present application is to provide a segmented stiffness collaborative design method for an underwater suspended tunnel, which can design the pipe body, anchor cable and joint stiffness that meet the driving requirements, and is a direct design method to solve the technical problems proposed in the background art.

[0008] To achieve the above-mentioned purpose, the present application provides the following technical solution: a segmented stiffness collaborative design method for an underwater suspended tunnel, at least comprising the following steps:

[0009] S1: preliminarily determining the anchor cable arrangement position and arrangement spacing according to the underwater suspended tunnel site terrain data;

[0010] S2: determining the pipe section clearance, and determining multiple standards under the traffic requirements, such as the maximum vertical and horizontal displacement of the pipe section, the maximum horizontal and vertical deformation of the joint, the maximum angle of the joint, etc., according to the underwater suspended tunnel traffic design requirements;

[0011] S3: obtaining the minimum bending stiffness of the pipe body or the minimum elastic modulus under the constant inertia moment according to the maximum deflection of the single pipe section and the beam deflection formula, segmenting the tunnel pipe section, disconnecting the pipe section from the middle of the two groups of anchor cables or dividing a group of anchor cables into two groups of anchor cables with half the area, assuming that the pipe section except the revetment section is not affected by the adjacent pipe section, and at the same time, the force balance with the connected anchor cable can be formed;

[0012] S4: according to the pipe section and load obtained from S3, the load borne by the single pipe section is f i (x), and the load and the stiffness of the anchor cable are calculated under the force balance;

[0013] S5: according to the design traffic requirements, the maximum deflection of the pipe section and the maximum deformation of the full span are known, the beam deflection curve under the uniform load is taken as the reference, that is, a quadratic parabola, a quadratic parabola is taken as the full span deformation control curve, the opening of the taken quadratic parabola is downward, the two ends of the underwater suspended tunnel are taken as the two ends of the curve, the coordinates are (0, 0) and (L, 0), and the vertex is the midpoint of the tunnel, the coordinates are (L / 2, Δ max );

[0014] S6: according to the displacement design amount of each anchor cable position point minus the deflection of the single pipe section, the displacement amount of the anchor cable is obtained, and then the vertical total stiffness of the anchor cable is obtained through the stiffness formula (K=F / Δ), and the cross-sectional area of the anchor cable at each position under the fixed material is calculated through the formula, and the stiffness design of the anchor cable is completed;

[0015] S7: after the stiffness design of the anchor cable is completed, the end bending moment of the pipe section under the load is obtained based on the displacement method basic formula according to the single pipe section simplified model, and the joint bending stiffness (KJ = M / θ);

[0016] S8: Joint axial stiffness calculation, the main component of joint axial stiffness is GINA water stop, the stiffness of which is determined by the water pressure of the underwater suspended tunnel;

[0017] S9: Shear stiffness calculation of joint structure, the ratio of total force on single pipe segment to shear displacement limit value of joint structure;

[0018] S10: The torque caused by horizontal displacement of the joint is calculated from the force and displacement relationship at the joint position, and the torsional stiffness of the joint structure is obtained according to the maximum torsional deformation limit value of the joint.

[0019] Further, the maximum deflection of the single pipe segment in S3 and the beam deflection formula refer to the following formula 1:

[0020] δ tube = 5ql 4 / 384EI V (1)

[0021] Where: δ tube represents the deflection of the pipe body under uniform load q; l represents the length of the pipe body; E represents the elastic modulus of the pipe body; I v represents the vertical moment of inertia of the pipe body.

[0022] Further, the calculation of the load on the anchor cable and the stiffness of the anchor cable in S4 is shown in the following formula 2 and formula 3:

[0023]

[0024] K c,i = f i (p) / Δ i = f i (p) / (g i (x)-δ tube )(3)

[0025] Where: f i,side (x) represents the total vertical load allocated to the anchor cable group i of the side span segment after tunnel segmentation; f i,mid (x) represents the total vertical load allocated to the anchor cable group i of the midspan segment after tunnel segmentation; C side represents the correction parameter of the total vertical load allocated to the anchor cable i of the side span segment; s represents the length of the pipe segment after tunnel segmentation; p(x) represents the load function of the tunnel, which is equal to q when the load is uniform load; x represents the horizontal coordinate, with one end of the tunnel as the starting point and the other end as the terminal point; f i (p) represents the total vertical load on the anchor cable group i under the load function p; Δ iThe maximum deflection of a single pipe section that satisfies the design requirement deformation function g(x) under the load function p of the pipe section used.

[0026] Further, the formula for calculating the cross-sectional area of the anchor cable at each position under the fixed material is as follows:

[0027] k c,i = E c A c = {K c,i l c / 2sin 2 α, K c,i l c / 2cos 2 α} Max (4)

[0028] wherein k c,i represents the tensile stiffness of a single anchor cable in the anchor cable group i; E c represents the elastic modulus of the anchor cable; A c represents the cross-sectional area of the anchor cable; l c represents the length of the anchor cable; and α represents the inclination angle of the anchor cable.

[0029] Further, the algorithm used in S7 is as follows:

[0030] θ H,V = q H,V l 3 / 12(2+K JH,JV l / EI H,V )EI H,V (5)

[0031]

[0032] wherein θ H,V represents the deformation at the joint position in the horizontal or vertical direction of the pipe section under the horizontal or vertical load q H,V ; K JH,JV represents the horizontal or vertical stiffness of the joint; EI H,V represents the horizontal or vertical bending stiffness of the pipe section; θ Max represents the maximum rotation angle limit of the end of the pipe section; and θ Cable,1 represents the rotation deformation equivalent to Δ H1,V1 caused by the deformation of the anchor cable in the side span section.

[0033] Further, the joint axial stiffness in S8 is calculated as follows:

[0034] K u = 2πR GINA k u (8)

[0035] wherein: K u represents the axial stiffness of the joint; R GINA represents the radius of the GINA waterstop; k u represents the axial stiffness of the GINA waterstop per unit length.

[0036] Further, the shear stiffness of the joint structure in S9 is calculated as follows in formula 9:

[0037] K q = ql / Delta q,design (9)

[0038] wherein: K q represents the tangential stiffness of the joint; Delta q,design represents the maximum tangential deformation limit of the joint.

[0039] Further, the torque of the joint caused by the horizontal displacement is calculated in S10 as follows in formula 10:

[0040] F θ = K J,Shear r(tan alpha sin beta-cos beta) Delta h,Design (10)

[0041] wherein: F θ represents the torque generated when the joint is horizontally displaced; K J,Shear represents the shear stiffness of the joint; r represents the radius of the joint; alpha represents the installation angle of the anchor cable; beta represents the inclination angle of the anchor cable; Delta h,Design represents the maximum horizontal displacement limit of the joint.

[0042] Further, the process of calculating the torsional stiffness of the joint structure in S10 is as follows in formula 11:

[0043] K θ = K J,Shear r(tan alpha sin beta-cos beta) Delta h,Design / Delta θ,Design (11)

[0044] wherein: K θ represents the torsional stiffness of the joint; Delta θ,Design represents the maximum torsional limit of the joint.

[0045] Compared with the prior art, the beneficial effects of the present application are:

[0046] 1. The method disclosed in the present application fills the technical gap in the design of the stiffness of the underwater suspended tunnel structure, promotes the development of the underwater suspended tunnel, and provides a more controllable and more universal design method.

[0047] 2、The joint stiffness design in the application is a brand-new design concept, which solves the problem that the joint structure of the suspended tunnel is not designed by anyone at present.

[0048] 3、The anchor cable stiffness design method in the application adopts an innovative segmentation method, decouples the coupling effect between multiple pipe sections, and achieves good results after design, producing better structure response and mitigated displacement curve compared with the existing pre-tightening force optimization design.

[0049] Moreover, the method can also be used for cable adjustment of a cable-stayed bridge, also using the segmentation method, and finally designing the vertical stiffness of each cable according to the force and displacement requirements of each section to obtain the total stiffness.

[0050] 4、The pipe body stiffness design method in the application provides help and suggestions for stiffness performance of pipe body material selection and reinforcement design. DETAILED DESCRIPTION

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0052] Figure 1 The technical roadmap of the application;

[0053] Figure 2 The segmentation method used in the application is illustrated;

[0054] Figure 3 The displacement and bending moment response difference diagram when the design method in the application and the existing method are used under static load;

[0055] Figure 4 The displacement and bending moment response difference diagram when the design method in the application and the existing method are used under dynamic load;

[0056] Figure 5 The preliminary design diagram when the application is applied to a strait;

[0057] Figure 6 The wave force borne by the underwater suspended tunnel using the design method of the application in a certain strait;

[0058] Figure 7 The anchor cable stiffness designed according to static and dynamic load respectively after the design method of the application is used in a certain strait;

[0059] Figure 8The displacement and bending moment response diagram of the underwater suspended tunnel of the application under static load after using the design method of the application for a certain strait;

[0060] Figure 9 The displacement response diagram of the underwater suspended tunnel of the application under dynamic load after using the design method of the application for a certain strait;

[0061] Figure 10 The bending moment response diagram of the underwater suspended tunnel of the application under dynamic load after using the design method of the application for a certain strait. DETAILED DESCRIPTION

[0062] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, rather than all the embodiments of the application.

[0063] Embodiment one:

[0064] The embodiment discloses a segmented stiffness collaborative design method for an underwater suspended tunnel. It should be noted that the method can be divided into a segmented simplification method of a model and a stiffness detailed design method of a pipe body, an anchor cable and a joint.

[0065] Please refer to Figure 1 A segmented stiffness collaborative design method for an underwater suspended tunnel, at least including the following steps:

[0066] S1: preliminarily determining anchor cable arrangement positions and arrangement intervals according to underwater suspended tunnel site area topographic data;

[0067] S2: determining a pipe section clearance and determining multiple standards under traffic requirements, such as maximum vertical and horizontal displacements of a pipe, maximum horizontal and vertical deformations of a joint and maximum rotation angle of a joint, according to underwater suspended tunnel traffic design requirements;

[0068] S3: obtaining minimum bending stiffness or minimum elastic modulus under a constant moment of inertia of a pipe body according to a maximum deflection formula of a single pipe and a beam deflection formula, segmenting the tunnel pipe, disconnecting the pipe from the middle of two groups of anchor cables or dividing a group of anchor cables into two groups of anchor cables with halved areas, assuming that the pipe segments except for a revetment segment are not affected by adjacent pipe segments and can form force balance with connected anchor cables;

[0069] The maximum deflection formula of a single pipe and the beam deflection formula are shown in the following formula 1:

[0070] δ tube = 5ql 4 / 384EI V (1)

[0071] wherein: δ tubeDeflection of the tube under uniform load q; l represents the length of the tube; E represents the elastic modulus of the tube; I represents the vertical moment of inertia of the tube v represents the vertical moment of inertia of the tube.

[0072] S4: According to the individual pipe sections and loads obtained from S3, the load borne by a single pipe section is f i (x), under force balance, the load borne by the anchor cable and the stiffness of the anchor cable are calculated, please refer to Figure 2 ;

[0073] The load borne by the anchor cable and the stiffness of the anchor cable are calculated as shown in the following formula 2 and formula 3:

[0074]

[0075] K c,i = f i (p) / Δ i = f i (p) / (g i (x)-δ tube )(3)

[0076] wherein: f i,side (x) represents the total vertical load allocated to the anchor cable group i of the side span section after the tunnel is segmented; f i,mid (x) represents the total vertical load allocated to the anchor cable group i of the midspan section after the tunnel is segmented; C side represents the correction parameter of the total vertical load allocated to the anchor cable i of the side span section; s represents the length of the pipe section of the segmented tunnel; p(x) represents the load function borne by the tunnel, which is equivalent to q when the load is uniform load; x represents the transverse coordinate, with one end of the tunnel as the starting point and the other end as the terminal point; f i (p) represents the total vertical load borne by the anchor cable group i under the load function p; Δ i represents the maximum deflection of a single pipe section that meets the design requirement deformation function g(x) of the pipe section under the load function p.

[0077] S5: According to the design traffic requirements, the maximum deflection of the pipe section and the maximum deformation of the full span, the deflection curve of the beam body under the uniform load is taken as a reference, that is, a quadratic parabola, and a quadratic parabola is taken as the full span deformation control curve. The opening of the taken quadratic parabola is downward, and the two ends of the underwater suspended tunnel are taken as the two ends of the curve, the coordinates of which are (0, 0) and (L, 0), and the vertex is the midpoint of the tunnel, the coordinates of which are (L / 2, Δ max );

[0078] S6: According to the displacement design amount of each anchor cable position point minus the deflection of a single pipe section, the anchor cable displacement amount is obtained, and then the vertical total stiffness of the anchor cable is obtained through the stiffness formula (K=F / Δ). The cross-sectional area of the anchor cable at each position under the fixed material is calculated through the formula, and the anchor cable stiffness design is completed.

[0079] The formula for calculating the cross-sectional area of the anchor cable at each position under the fixed material is as follows:

[0080] k c,i = E c A c = {K c,i l c / 2sin 2 α,K c,i l c / 2cos 2 α} Max (4)

[0081] wherein: k c,i represents the tensile stiffness of a single anchor cable in anchor cable group i; E c represents the elastic modulus of the anchor cable; A c represents the cross-sectional area of the anchor cable; l c represents the length of the anchor cable; and a represents the inclination angle of the anchor cable.

[0082] S7: After the anchor cable stiffness design is completed, the end bending moment of the pipe section under load can be obtained based on the displacement method basic formula according to the single pipe section simplified model, and the joint maximum angle obtained in S2 is the pipe end angle limit, and the joint bending stiffness (K J = M / θ) is obtained.

[0083] The algorithm used is shown in the following formulas 5-7:

[0084] θ H,V = q H,V l 3 / 12(2+K JH,JV l / EI H,V )EI H,V (5)

[0085]

[0086] wherein: θ H,V represents the deformation of the joint position in the horizontal or vertical direction under the horizontal or vertical load q H,V ; K JH,JV represents the horizontal or vertical stiffness of the joint; EI H,V represents the horizontal or vertical bending stiffness of the pipe section; θ Max represents the maximum angle limit of the pipe end; and θ Cable,1 represents the angle deformation caused by the deformation of the side span segment by the anchor cable, which is equivalent to Δ H1,V1 .

[0087] S8: Joint axial stiffness calculation, the main component of the joint axial stiffness is GINA water stop, and the stiffness of the water stop is determined by the water pressure used in the underwater suspended tunnel;

[0088] The joint axial stiffness is calculated as follows in equation 8:

[0089] K u = 2πR GINA k u (8)

[0090] Wherein: K u represents the joint axial stiffness; R GINA represents the radius of the GINA water stop; k u represents the axial stiffness per unit length of the GINA water stop.

[0091] S9: The shear stiffness of the joint structure is calculated as the ratio of the total force on the single pipe section to the shear displacement limit of the joint structure;

[0092] The shear stiffness of the joint structure is calculated as follows in equation 9:

[0093] K q = ql / Δ q,design (9)

[0094] Wherein: K q represents the joint shear stiffness; Δ q,design represents the maximum shear deformation limit of the joint.

[0095] S10: The torque on the joint due to horizontal displacement is calculated from the force-displacement relationship at the joint location, and the torsional stiffness of the joint structure is then obtained based on the maximum torsional deformation limit of the joint.

[0096] The torque on the joint due to horizontal displacement is calculated as follows in equation 10:

[0097] F θ = K J,Shear r(tanαsinβ-cosβ)Δ h,Design (10)

[0098] Wherein: F θ represents the torque generated when the joint is horizontally displaced; K J,Shear represents the joint shear stiffness; r represents the joint radius; α represents the anchor installation angle; β represents the anchor inclination angle; Δ h,Design represents the maximum horizontal displacement limit of the joint.

[0099] The process of obtaining the torsional stiffness of the joint structure is as follows in equation 11:

[0100] K θ = K J,Shear r(tanαsinβ-cosβ)Δ h,Design / Δ θ,Design (11)

[0101] wherein: K θ represents the joint torsional stiffness; Δ θ,Design represents the maximum torsional limit of the joint.

[0102] Example Two:

[0103] In this example, the anchor cable design method in the method is taken as the main variable, and the design method of the pipe body and the joint is not used temporarily in order to reduce the influence of other variables on the example. Under static and dynamic loads, the displacement and bending moment response of the underwater suspended tunnel is studied, and it is proved that the method has good controllability and universality. Specifically as follows:

[0104] The total length of the suspended tunnel in this example is 1000m, the single pipe section is 100m long, the pipe body adopts high-strength waterproof concrete, the tunnel cross section is circular, the inner diameter is 6.5m, the outer diameter is 7.5m, the material density is determined to be 3066kg / m3 by the floating weight ratio of 1.3, and the Young's modulus and Poisson's ratio of the pipe wall material are determined to be 34.5GPa and 0.2 respectively; the anchor cable of the suspended tunnel is hinged under the anchor spindle, and the installation angle and the inclination angle are both 60°; the anchor cable is a high-strength steel rope with a length of 180m and a diameter of 0.347m, and the material density, Young's modulus and Poisson's ratio are 8000kg / m3, 195GPa and 0.3 respectively, and the anchor cable is uniformly distributed along the tunnel axis with an interval of 100m and a total of 9 groups. In the design environment, the suspended tunnel is subjected to periodic wave load, the wave height is 7m, the period is 12.69s, and the wave force is calculated by potential flow theory.

[0105] The suspended tunnel structure with or without the structure of the application is analyzed for static and dynamic response, including the following steps:

[0106] Step one: select 10 tunnel pipe sections with a length of 100m, the material density, Young's modulus and Poisson's ratio are 3066kg / m3, 34.5GPa and 0.2 respectively, the pipe sections are connected through joints with the same stiffness as the pipe body, and the two ends of the tunnel are hinged to the ground and constrained in torsion.

[0107] Step two: select anchor cables with a length of 180m and a diameter of 0.347m, the material density, Young's modulus and Poisson's ratio are 8000kg / m3, 195GPa and 0.3 respectively. The anchor cables are uniformly distributed along the tunnel axis with an interval of 100m, a total of 9 groups, and the left and right ends of the anchor cable at the upper end of each group are connected to the outer surface of the tunnel pipe section by MPC beam constraint, and the lower end of the anchor cable is hinged to the ground.

[0108] Step three: adjust the pretightening force value of each part of the anchor cable by the anchor cable pretightening force adjustment method to obtain the best displacement and bending moment response results;

[0109] Step four: repeat steps one, two, and three, but in step three, use the segmented design method described in the invention to directly determine the vertical stiffness required at each anchor position, thereby obtaining the diameter of each anchor.

[0110] Step five: apply static loads (self-weight and buoyancy) and dynamic loads (static load plus wave force) to the two models, respectively, and compare the dynamic response results of the suspended tunnel structure with and without the structure of the invention.

[0111] As shown in Figure 3 , the dynamic response of the suspended tunnel under static load before and after using the design method of the invention is compared. It can be seen that the suspended tunnel structure using the invention has a greater positive impact on vertical displacement and vertical bending moment response, with smaller displacement and more uniform bending moment under the same conditions.

[0112] As shown in Figure 4 , the displacement response of the suspended tunnel under periodic wave load before and after using the design method of the invention is compared. It can be seen that under the action of periodic wave load, the displacement of the suspended tunnel structure with the invention is smaller, and the displacement curve is more moderate.

[0113] Example three:

[0114] In this example, the actual terrain of a proposed project in the Mediterranean region is used as the application scenario, and the design method is used in detail. Finally, it is compared with multiple constraint conditions to prove that the method of the invention has good controllability and universality. Specifically as follows:

[0115] First, through its topographic map, the anchor cable distribution and pipe segment immersion depth are preset, as shown in Figure 5 , where l C1 is the vertical height of the mid-span anchor cable (mid-span anchor cable length l1 = 235 m); l C0 is the vertical height of the side-span anchor cable (side-span anchor cable length l0 = 142 m); S1 is the length of the mid-span pipe segment (S1 = 100 m); S0 is the length of the side-span pipe segment (S0 = 150 m). According to existing research, the immersion depth is 40 m, the float-to-weight ratio is 1.3, the structure length is 2900 m, and the specific parameters are as shown in Table 1.

[0116] Table 1

[0117]

[0118] The maximum wave height in this area is about 3 m, and the period is 12.69 s, so the wave load, gravity, and buoyancy under this sea condition are used as the load for research, and the wave force on the structure is calculated by potential flow theory method (as shown in Figure 6), because the horizontal and vertical wave forces are similar in magnitude, and the vertical direction has the action of residual buoyancy (one order of magnitude greater than the two), the design criterion is mainly the deformation limit of the vertical direction pipe segment, which can meet the horizontal displacement requirements.

[0119] Assuming that the tunnel traffic requirements are driving speed 200km / H, according to the current design standards, the standard for safe driving is shown in Table 3. According to the limit of pipe body deformation, the vertical stiffness required by each anchor point is determined, such as Figure 7 , and the required anchor section area is determined according to the length and angle of each anchor point. The joint shear, axial and torsional stiffness and the bending stiffness determined by the internal force optimization method in this paper are shown in Table 2.

[0120] Table 2

[0121]

[0122] As shown in Figure 8 , Figure 9 , Figure 10 and Table 3, under static and periodic load, the displacement and bending moment response of the structure meet the expectations and meet the use requirements.

[0123] Table 3

[0124]

[0125] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

Claims

1. A method for segmental stiffness collaborative design of an underwater suspended tunnel, characterized in that: At least comprising the following steps: S1: According to the underwater suspended tunnel tunnel site terrain data, the anchor cable layout position and layout spacing are preliminarily determined; S2: According to the underwater suspended tunnel traffic design requirements, the pipe section clearance is determined, and a plurality of standards under the traffic requirements are determined, including the maximum vertical and horizontal displacement of the pipe section, the maximum horizontal and vertical deformation of the joint, and the maximum rotation angle of the joint; S3: According to the maximum deflection of the single pipe section and the beam deflection formula, the minimum bending stiffness of the pipe body or the minimum elastic modulus under the constant inertia moment is obtained, the tunnel pipe section is segmented, the pipe section is disconnected from the middle of the two groups of anchor cables or one group of anchor cables is divided into two groups of anchor cables with half the area, and it is assumed that the pipe section except the revetment section is not affected by the adjacent pipe section, and at the same time, the force balance can be formed with the connected anchor cable; S4: each pipe segment and load obtained from S3 segment, single pipe segment load is f i (x), under the force balance, the load and the anchor stiffness of the anchor cable are calculated; S5: According to the design traffic requirements, the maximum deflection of the pipe section and the maximum deformation of the whole span are known. The beam deflection curve under uniform load is a quadratic parabola, which is taken as a reference. A quadratic parabola is taken as the whole span deformation control curve. The opening of the quadratic parabola is downward, and the two ends of the underwater suspended tunnel are taken as the two ends of the curve, the coordinates (0, 0) and (L, 0), and the vertex is the midpoint of the tunnel, the coordinates (L / 2, max ); S6: According to the displacement design amount of each anchor cable position point minus the single pipe section deflection, the anchor cable displacement amount is obtained, and then the total vertical stiffness of the anchor cable is obtained through the stiffness formula K=F / ∆, and the cross-sectional area of the anchor cable at each position under the fixed material is obtained through formula calculation, and the anchor cable stiffness design is completed; S7: After the completion of the anchor cable stiffness design, the bending moment of the pipe end under load can be obtained based on the displacement method basic formula according to the single pipe section simplified model, and the joint bending stiffness K is obtained by combining the maximum joint rotation angle obtained in S2, i.e. the pipe end rotation angle limit value. J =M / θ; The algorithm used in S7 refers to the following formula 5-7: （5）； （6）； （7）； where: θ H,V represents the horizontal or vertical load q H,V represents the deformation at the joint location; K JH,JV represents the horizontal or vertical stiffness of the joint; EI H,V represents the horizontal or vertical bending stiffness of the pipe section; θ Max represents the maximum rotation limit of the pipe section end; θ Cable,1 represents the rotation deformation of the side span section caused by the deformation of the anchor cable, which is equivalent to H1,V1 ; S8: Joint axial stiffness calculation, the main component of the joint axial stiffness is GINA water stop, and the stiffness of the water stop is determined by the water pressure used by the underwater suspended tunnel; S9: Shear stiffness calculation of joint structure, which is the ratio of the total force on the single pipe section to the shear displacement limit value of the joint structure; S10: With the anchor cable as the medium, the torque of the joint caused by the horizontal displacement is calculated from the force and displacement relationship at the joint position, so that the torsional stiffness of the joint structure is obtained according to the maximum torsional deformation limit value of the joint.

2. The method for segmental stiffness collaborative design of an underwater suspended tunnel according to claim 1, characterized in that: The single pipe section maximum deflection and beam deflection formula in S3 refers to the following formula 1: （1）； wherein: δ tube represents the deflection of the pipe body under the uniform load q; l represents the length of the pipe body; E represents the elastic modulus of the pipe body; I v represents the vertical moment of inertia of the pipe body.

3. The method for segmental stiffness collaborative design of an underwater suspended tunnel according to claim 2, characterized in that: The joint axial stiffness calculation in S8 is as follows: K u = 2πR GINA k u (8); where: K u represents the joint axial stiffness; R GINA represents the radius of the GINA waterstop; k u represents the axial stiffness per unit length of the GINA waterstop.

4. The method for segmental stiffness collaborative design of an underwater suspended tunnel according to claim 3, characterized in that: The shear stiffness calculation of the joint structure in S9 is as follows: ； where: K q represents the joint tangential stiffness; q,design represents the joint maximum tangential deformation limit.

5. The method for segmental stiffness collaborative design of an underwater suspended tunnel according to claim 4, characterized in that: The torque of the joint caused by the horizontal displacement in S10 is calculated as follows: （10）； where: F θ represents the torque generated when the joint is displaced horizontally; K J,Shear represents the joint shear stiffness; r represents the joint radius; a represents the anchor installation angle; b represents the anchor inclination angle; h,Design represents the maximum horizontal displacement limit of the joint.

6. The method for segmental stiffness collaborative design of an underwater suspended tunnel according to claim 5, characterized in that: The process of obtaining the torsional stiffness of the joint structure in S10 is as follows: （11）； where: K θ represents the joint torsional stiffness; θ,Design represents the maximum joint torsional limit.

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