WO2022165983A1 - 一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法 - Google Patents

一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法 Download PDF

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WO2022165983A1
WO2022165983A1 PCT/CN2021/086371 CN2021086371W WO2022165983A1 WO 2022165983 A1 WO2022165983 A1 WO 2022165983A1 CN 2021086371 W CN2021086371 W CN 2021086371W WO 2022165983 A1 WO2022165983 A1 WO 2022165983A1
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tower
longitudinal
spring stiffness
longitudinal spring
main
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PCT/CN2021/086371
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English (en)
French (fr)
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肖海珠
张建强
高宗余
别业山
李松林
唐超
戴慧敏
黄赟
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中铁大桥勘测设计院集团有限公司
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Priority to EP21923992.8A priority Critical patent/EP4099207A4/en
Publication of WO2022165983A1 publication Critical patent/WO2022165983A1/zh

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/17—Mechanical parametric or variational design
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/13—Architectural design, e.g. computer-aided architectural design [CAAD] related to design of buildings, bridges, landscapes, production plants or roads
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2111/00—Details relating to CAD techniques
    • G06F2111/04—Constraint-based CAD
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/16—Cables, cable trees or wire harnesses
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces

Definitions

  • the invention relates to the technical field of bridge engineering, in particular to a method for determining the longitudinal restraint rigidity of a tower beam of a three-tower cable-stayed bridge and optimizing the foundation.
  • the three-tower cable-stayed bridge can be arranged with two navigation holes to meet the navigation needs, and its economy has an absolute advantage compared with the two-tower cable-stayed bridge covering the same navigation area. Therefore, it is extremely competitive in the selection of bridge schemes.
  • the middle tower is different from the side tower, and lacks the restraining effect of the anchor cables at the side span ends.
  • the mid-span displacement is large, the structural rigidity is weak, the tower bottom bending moment of the middle tower also increases significantly, and the structural design difficulty increases, especially for the three-tower cable-stayed bridge with weak foundation, the excessively large tower bottom bending moment will increase The scale of the base will greatly increase the project cost.
  • the scheme of increasing the longitudinal restraint between the tower and the beam is adopted to reduce the equivalent force arm of the bridge tower to transmit the horizontal force, improve the structural rigidity and reduce the longitudinal bending moment of the tower root.
  • This scheme can effectively change the structural restraint system by adjusting the structure. Structural force transmission law.
  • this scheme when this scheme is adopted, how to determine the longitudinal restraint stiffness value between the pylons of the three-tower cable-stayed bridge? How to minimize the size of the structural base? How to make the longitudinal force of the side and middle tower of the three-tower cable-stayed bridge basically the same, so as to make the structure size of the bridge tower uniform and maintain the consistency and rhythm of the structural landscape?
  • the embodiment of the present invention provides a method for determining the longitudinal restraint stiffness of the tower beam of a three-tower cable-stayed bridge and optimizing the foundation.
  • the foundation scale of the tower bottom of the middle tower is optimized and the middle tower is optimized to the greatest extent.
  • the base scale of the tower base is optimized.
  • the present embodiment provides a method for determining the longitudinal restraint stiffness of a three-tower cable-stayed bridge tower and girder and an optimization foundation, characterized in that the method includes: establishing a basic model with the longitudinal free expansion and contraction of the main girder at the side tower as the first boundary condition; Taking the longitudinal spring constraint of the main beam at the side tower as the second boundary condition, the initial value of the longitudinal spring stiffness under the second boundary condition is obtained in the basic model; The functional relationship between the longitudinal bending moment and the longitudinal spring stiffness is determined under the additional working conditions; based on the functional relationship between the longitudinal bending moment and the longitudinal spring stiffness, the relationship between the reaction force at the bottom of the side tower pile foundation and the longitudinal spring stiffness is determined.
  • the initial value of the longitudinal spring stiffness under the second boundary condition is obtained in the basic model by taking the longitudinal spring constraint of the main beam at the side tower as the second boundary condition, including: applying at the mid-span of the main beam;
  • the unit horizontal force is denoted as P;
  • the initial value of the longitudinal spring stiffness is denoted as k 0 ;
  • the determining the functional relationship between the longitudinal bending moment and the longitudinal spring stiffness under the main force condition and the main additional condition based on the initial value of the longitudinal spring stiffness, respectively includes: initializing the longitudinal spring stiffness The different multiples of the value are the parameters that are substituted into the basic model to obtain the calculation results corresponding to different multiples; the corresponding longitudinal bending moments obtained by fitting the calculation results under the main working condition and the main additional working condition are Functional relationship between longitudinal spring stiffness.
  • the determining the functional relationship between the longitudinal bending moment and the longitudinal spring stiffness under the main force condition and the main additional condition, respectively, based on the initial value of the longitudinal spring stiffness includes determining: the edge under the main force condition; The functional relationship between the longitudinal bending moment of the tower bottom and the longitudinal spring stiffness; the functional relationship between the longitudinal bending moment and the longitudinal spring stiffness of the tower bottom of the middle tower under the main load condition; the longitudinal bending moment of the side tower under the main additional condition The functional relationship between the bending moment and the longitudinal spring stiffness; the functional relationship between the longitudinal bending moment and the longitudinal spring stiffness of the mid-tower bottom under the main additional condition.
  • determining the functional relationship between the side tower pile foundation pile bottom reaction force and the longitudinal spring stiffness based on the functional relationship between the longitudinal bending moment and the longitudinal spring stiffness includes determining: The functional relationship between the reaction force at the base of the tower pile foundation and the longitudinal spring stiffness; the functional relationship between the reaction force at the base of the side tower pile foundation and the longitudinal spring stiffness under the main additional condition.
  • determining the optimal value of longitudinal spring stiffness based on the functional relationship between the side tower pile foundation pile bottom reaction force and longitudinal spring stiffness includes: determining the optimal value of longitudinal spring stiffness according to a first formula ;
  • the first formula is: Among them, k is the longitudinal spring stiffness, N 1, the main force (0) is the functional relationship between the side tower pile foundation pile bottom reaction force and the longitudinal spring stiffness under the main force condition N 1, the main force (k) when k is 0
  • N 1 the function relationship between the reaction force of the side tower pile foundation and the longitudinal spring stiffness under the main + additional working condition
  • m1 is the improvement coefficient of the main working condition
  • m2 is The increase factor for the main additional condition.
  • update the section parameters of the basic model before substituting the optimal value of longitudinal spring stiffness into the basic model, update the section parameters of the basic model; the updating of the section parameters includes: substituting the optimal value of longitudinal spring stiffness into the longitudinal Calculate the internal force value of the longitudinal bending moment from the functional relationship between the bending moment and the longitudinal spring stiffness; adjust the longitudinal dimension of the side tower and the middle tower according to the internal force value of the longitudinal bending moment; input the adjusted longitudinal dimension of the section into the basic model for updating .
  • the adjusting the longitudinal dimension of the cross-section of the side tower and the middle tower according to the value of the longitudinal bending moment internal force includes: adjusting the longitudinal dimensions of the cross-section of the side tower and the middle tower to be the same size.
  • after the optimization of the base scale of the tower bottom it includes: updating the base model based on the optimized base scale; calculating the updated base model based on the optimal value of the longitudinal spring stiffness and the updated base model. If the updated value of the pile bottom reaction force of the middle tower pile foundation is less than the initial value of the pile bottom reaction force of the middle tower pile foundation corresponding to the basic model under the first boundary condition, continue to optimize the middle tower pile foundation.
  • the base scale of the tower base includes: updating the base model based on the optimized base scale; calculating the updated base model based on the optimal value of the longitudinal spring stiffness and the updated base model. If the updated value of the pile bottom reaction force of the middle tower pile foundation is less than the initial value of the pile bottom reaction force of the middle tower pile foundation corresponding to the basic model under the first
  • the optimization of the base size of the tower bottom includes: reducing the number of pile foundations; reducing the size of the cap.
  • the embodiment of the present invention provides a method for determining the longitudinal restraint stiffness of the tower beam of a three-tower cable-stayed bridge and optimizing the foundation, wherein by providing a clear-purpose, easy-to-operate, The method of determining the optimal value of longitudinal spring stiffness of the three-tower cable-stayed bridge tower has obvious effect, and the foundation scale is optimized by the optimal value of longitudinal spring stiffness.
  • the optimal solution of the longitudinal restraint stiffness value between the tower beams of the three-tower cable-stayed bridge can be obtained, and the foundation scale of the main tower can be optimized to the greatest extent.
  • Fig. 1 is a kind of schematic flow chart of the method for determining the longitudinal restraint stiffness of the tower beam and the optimization foundation of the three-tower cable-stayed bridge provided by the embodiment of the present invention
  • FIG. 2 is a schematic structural diagram of a three-tower cable-stayed bridge tower provided by an embodiment of the present invention
  • FIG. 3 is a schematic structural diagram of a three-tower cable-stayed bridge tower under a second boundary condition provided by an embodiment of the present invention
  • Fig. 4 is the functional relationship between the longitudinal bending moment of the side tower tower bottom and the longitudinal spring stiffness provided by the embodiment of the present invention
  • Fig. 5 is the functional relationship between the longitudinal bending moment of the bottom of the middle tower and the longitudinal spring stiffness provided by the embodiment of the present invention
  • FIG. 6 is a schematic diagram of determining an optimal value of longitudinal spring stiffness based on a first formula according to an embodiment of the present invention
  • FIG. 7 is a schematic diagram of calculating the reaction force value at the bottom of the tower pile foundation based on the optimal value of the longitudinal spring stiffness according to the embodiment of the present invention.
  • an embodiment of the present invention provides a method for determining the longitudinal restraint stiffness of the tower beam and optimizing the foundation of a three-tower cable-stayed bridge, by calculating the optimal value of the longitudinal spring stiffness to optimize the foundation scale of the middle tower tower bottom And realize the maximum optimization of the base scale of the tower bottom.
  • the steps include:
  • S20 take the longitudinal spring constraint of the main beam at the side tower as the second boundary condition and obtain the initial value of the longitudinal spring stiffness under the second boundary condition in the basic model;
  • S40 determine the functional relationship between the side tower pile foundation pile bottom reaction force and the longitudinal spring stiffness based on the functional relationship between the longitudinal bending moment and the longitudinal spring stiffness;
  • S50 determine the optimal value of longitudinal spring stiffness based on the functional relationship between the side tower pile foundation pile bottom reaction force and the longitudinal spring stiffness;
  • the pylon foundations of the three-tower cable-stayed bridge towers are all pile group foundations at weak foundations, the stress mode of the pile foundations is the form of friction piles, and the pile foundation types of the side towers and the middle towers are the same diameter piles. Base.
  • step S10 the establishment of the basic model in step S10 is based on the premise that the main beam is longitudinally fixed at the middle tower.
  • Step S10 also includes performing finite element analysis on the established basic model, and determining the basic scale and size of the structure corresponding to the basic model, including: the longitudinal dimension of the cross-section of the side tower and the middle tower, and the size of the bearing platform of the side tower and the middle tower and the number of pile foundations.
  • the longitudinal dimension of the main tower of the side tower is smaller than the longitudinal dimension of the middle tower in the design; under the same geological conditions, the scale of the pile foundation at the bottom of the side tower is smaller than that of the middle tower, that is, the pile at the bottom of the side tower is smaller.
  • the number of foundations is smaller than the number of pile foundations at the bottom of the middle tower, and the structural dimension of the base of the side tower is also smaller than that of the base of the middle tower.
  • step S20 in order to calculate the longitudinal constraint stiffness at the side tower, the first boundary condition in step S10 is adjusted from longitudinal free expansion and contraction to longitudinal spring constraint.
  • the initial value of longitudinal spring stiffness can be calculated based on the basic model and the set spring constraints.
  • the specific steps of determining the initial value of the longitudinal spring stiffness include:
  • the main force condition and the main additional condition respectively correspond to the cases in which the longitudinal bending moment of the tower bottom is caused under different load conditions.
  • the main force condition refers to the case where the live load causes the longitudinal bending moment of the tower bottom
  • the main additional condition refers to the case where the main force condition and the additional force condition act at the same time
  • the additional force condition refers to the additional force Conditions that give rise to longitudinal bending moments at the tower base, and the additional forces include wind loads, temperature loads, and braking forces.
  • step S30 and step S40 can be obtained by numerical method fitting in the basic model based on the initial value of longitudinal spring stiffness and different working conditions.
  • the functional relationship between the side tower pile foundation pile bottom reaction force and the longitudinal spring stiffness described in step S50 is a functional relationship under the main force condition and the main additional condition.
  • the optimal value of longitudinal spring stiffness can be determined based on the graphical data analysis of the functional relationship under two different working conditions.
  • the initial value of the pile bottom reaction force of the middle tower pile foundation corresponding to the basic model under the first boundary condition described in step S70 is obtained by substituting the boundary condition that the longitudinal restraint stiffness between the tower beams at the side tower is 0 into the basic model.
  • the reaction force at the bottom of the middle tower pile foundation calculated in the model.
  • the precondition for optimizing the base scale of the middle tower is that the reaction force value of the middle tower pile foundation is less than the initial reaction force value of the middle tower pile foundation corresponding to the basic model under the first boundary condition.
  • the optimal value of the longitudinal spring stiffness of the three-tower cable-stayed bridge tower is determined.
  • the method has a clear purpose, easy operation and obvious effect. Optimizing the foundation scale through the optimal value of longitudinal spring stiffness can effectively reduce the scale of the middle tower pile foundation and reduce the engineering cost.
  • step S30 includes:
  • the parameter in step S301, can be expressed as N k 0 , where N is an integer greater than zero, and k 0 is the initial value of the longitudinal spring stiffness.
  • the parameters may preferably be ⁇ k 0 , 2k 0 , 3k 0 , 10k 0 ⁇ .
  • the functional relationships described in steps S30 and S40 include:
  • the longitudinal bending moment M 1 at the bottom of the side tower under the main force condition, the main force (k), the longitudinal bending moment M 2 at the bottom of the middle tower under the main force condition and the main additional condition, the main force (k) and M 2 is the decreasing function of the longitudinal spring stiffness k
  • the longitudinal bending moment of the side tower tower bottom under the main additional condition M 1 is the longitudinal spring stiffness k increasing function.
  • the functional relationship between the side tower pile foundation pile bottom reaction force and the longitudinal spring stiffness described in step S50 includes:
  • N 1 main + additional (k).
  • the reaction force at the base of the side tower pile under the main force condition is N 1
  • the main force (k) is the decreasing function of the longitudinal spring stiffness k
  • main + append (k) is an increasing function of longitudinal spring stiffness k.
  • step S50 includes: determining the optimal value of the longitudinal spring stiffness according to the first formula
  • the first formula is: Among them, k is the longitudinal spring stiffness, N 1, the main force (0) is the functional relationship between the side tower pile foundation pile bottom reaction force and the longitudinal spring stiffness under the main force condition N 1, the main force (k) when k is 0
  • N 1 the function relationship between the reaction force of the side tower pile foundation and the longitudinal spring stiffness under the main + additional working condition
  • m1 is the improvement coefficient of the main working condition
  • m2 is The increase factor for the main additional condition.
  • k' in Fig. 5 is the optimal value of longitudinal spring stiffness.
  • the improvement coefficient m1 1 for the main working condition
  • the improvement coefficient m2 1.2 for the main additional working condition.
  • the basic model before substituting the optimal value of longitudinal spring stiffness into the basic model in step S60, the basic model is updated with section parameters; wherein the section parameter update includes the steps:
  • S60a-1 Substitute the optimal value of the longitudinal spring stiffness into the functional relationship between the longitudinal bending moment and the longitudinal spring stiffness to calculate the internal force value of the longitudinal bending moment;
  • S60a-2 Adjust the longitudinal dimension of the side tower and the middle tower according to the internal force value of the longitudinal bending moment
  • S60a-3 Input the adjusted longitudinal dimension of the section into the basic model for updating.
  • the cross-sectional longitudinal dimensions of the side tower and the middle tower can be adjusted to the same size.
  • the side and middle towers have the same tower shape, the same lateral force, and the same lateral dimensions of the side and middle tower sections.
  • the appearance and dimensions of side tower 3 and middle tower 2 can be unified, and the consistency and rhythm of the structure and landscape are the strongest.
  • the basic model is further optimized by updating the section parameters of the basic model, so that subsequent calculations can be performed based on the optimized basic model, which improves the accuracy of optimization.
  • step S70 after optimizing the basic scale of the bottom of the middle tower in step S70, it also includes the steps:
  • S70b-2 Calculate the updated reaction force value at the bottom of the middle tower pile foundation based on the optimal value of the longitudinal spring stiffness and the updated basic model;
  • the foundation scale of the bottom of the middle tower can be reduced to the same as that of the bottom of the side tower when the foundation scale is optimized.
  • optimizing the foundation size of the mid-tower bottom includes reducing the number of pile foundations and reducing the size of the cap.
  • the three-tower cable-stayed bridge tower shown in FIG. 2 is a bridge on a weak foundation, and the foundation 6 of the side tower 3 and the middle tower 2 is a cap 7 and a pile foundation 8 plan. Due to the stress characteristics of the three-tower cable-stayed bridge structure, the longitudinal dimension of the middle tower 2 is too large.
  • the longitudinal dimension from the top to the bottom of the middle tower 2 is 8m ⁇ 13m; 10m; the foundation 6 of the middle tower 2, that is, the cap 7 and the pile foundation 8, is obviously larger than the foundation 6 of the side tower 1.
  • the size of the cap 7 of the side tower 3 is 71 ⁇ 36m; the pile foundation 8 is 52 pile foundations with a diameter of 2.5m.
  • the size of the bearing platform 7 of the middle tower 2 is 74 ⁇ 39m; the pile foundation 8 is 60 pile foundations with a diameter of 2.5m.
  • the main girder 1 is set at the middle tower 2 with a longitudinal fixed constraint 4, and the side tower 3 is longitudinally free to expand and contract as The basic model of the boundary conditions is established, and the finite element analysis is carried out to determine the basic scale and size of the structure.
  • the main beam in the basic model is 1
  • the optimal value of longitudinal spring stiffness k' is substituted into the corresponding functional relationship, and the longitudinal bending moment of the side tower tower bottom M 1, the main force (37500) and M 1, the main + annex (37500) and the longitudinal bending moment of the middle tower tower bottom are obtained.
  • the side tower 3 can be preferably The longitudinal dimension of the section of the middle tower 2 is adjusted to the same size, that is, the longitudinal dimension from the top of the tower to the bottom of the tower is unified to 8m ⁇ 11.5m; after that, the basic model is updated according to the adjusted section of the side tower 3 and the middle tower 2, and the tower beam
  • the engineering geological conditions at the bottom of the side tower 3 and the bottom of the middle tower 2 are the same, so when the foundation scale is optimized, the scale of the pile foundation 8 at the bottom of the middle tower 2 can be reduced to the same scale as that of the pile foundation 8 at the bottom of the side tower 3, that is, the piles
  • the number remains the same, and 52 piles with a diameter of 2.5 are used.
  • the size of the bearing platform is also the same, both are 71 ⁇ 36m.
  • the middle tower 2 can be The longitudinal bending moment of the tower bottom is reduced by 21% and the foundation scale is reduced by 17%. It can be seen that the solution of the present invention can optimally reduce the longitudinal bending moment of the tower root and reduce the design difficulty and scale of the bridge tower and the bridge tower foundation 6 .
  • This embodiment provides a method for determining the longitudinal restraint stiffness of the tower and beam of a three-tower cable-stayed bridge and optimizing the base scale with a clear purpose, easy operation and obvious effect, and obtains the optimal solution of the longitudinal spring stiffness value.
  • the scale of the base 6 of the middle tower 2 is optimized to the greatest extent.
  • the external dimensions of side tower 3 and middle tower 2 are unified, and the consistency and rhythm of the structure and landscape are the strongest.
  • the terms “installed”, “connected” and “connected” should be understood in a broad sense, for example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, It can also be an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or an internal connection between two components.
  • installed should be understood in a broad sense, for example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, It can also be an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or an internal connection between two components.

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Abstract

一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，包括以主梁（1）在边塔（3）处纵向自由伸缩为第一边界条件建立基本模型；以主梁（1）在边塔（3）处纵向弹簧约束（5）为第二边界条件在基本模型中获取第二边界条件下的纵向弹簧刚度初始值；基于纵向弹簧刚度初始值分别在主力工况和主加附工况下确定纵向弯矩与纵向弹簧刚度之间的函数关系以及边塔（3）桩基桩底反力与纵向弹簧刚度之间的函数关系；进而确定纵向弹簧刚度最优值并对中塔（2）塔底的基础规模进行优化。该方法目的明确、易于操作、效果明显。通过纵向弹簧刚度最优值对基础规模进行优化，可有效减少中塔桩基规模，降低工程造价。

Description

一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法 技术领域
本发明涉及桥梁工程技术领域，特别涉及一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法。
背景技术
目前，由于三塔斜拉桥可布置两个通航孔以满足通航需求，而其经济性相比覆盖同等通航区域的两塔斜拉桥，具有绝对的优势。因此在桥梁方案比选中具有极强的竞争力。作为一种三塔斜拉桥结构，中塔有别于边塔，缺少边跨端锚索的约束作用，中塔的偏位比同跨径的两塔斜拉桥主塔大，进而主梁跨中位移大，结构刚度弱，中塔的塔底弯矩也大幅增加，结构设计难度增大，特别是针对软弱地基的三塔斜拉桥而言，过大的塔底弯矩会加大基础规模，进而会大幅增加工程造价。
为提高三塔斜拉桥结构的刚度，在相关技术中，有一些采用增加稳定索方案以限制中塔侧向偏位，如香港汀九大桥，但该方案破坏了斜拉桥简洁明快的景观效果；另有采用增加中塔结构尺寸及纵向刚度来“硬抗”荷载作用，如二七长江大桥，但该方案增加了中塔的塔底弯矩，在软弱地基情况下结构基础规模会大幅增加；另有采用增加塔、梁间纵向约束的方案，降低桥塔传递水平力的等效力臂，提高结构刚度并降低塔根纵向弯矩，该方案通过调整结构的约束体系，可有效地改变结构传力规律。但采用该方案时，如何确定三塔斜拉桥塔梁间的纵向约束刚度值？如何最大程度地降低结构基础规模？如何使三塔斜拉桥边、中塔纵向受力基本一致，以使桥塔结构尺寸统一从而保持结构景观一致性、韵律感？这些问题尚待研究。
研究发现，通过试算方式确定三塔斜拉桥塔梁间的纵向约束刚度值存在如下问题：试算时费时费力，工效因人而异，确定的刚度值不 一定是最优解，主塔基础规模还存在较大优化的空间，以及边、中塔结构尺寸还需进一步优化统一。
发明内容
本发明实施例提供一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，通过计算出纵向弹簧刚度最优值对中塔塔底的基础规模进行优化并实现最大程度优化中塔塔底的基础规模。
本实施例提供了一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，其特征在于，其包括：以主梁在边塔处纵向自由伸缩为第一边界条件建立基本模型；以主梁在边塔处纵向弹簧约束为第二边界条件，在所述基本模型中获取第二边界条件下的纵向弹簧刚度初始值；基于所述纵向弹簧刚度初始值分别在主力工况和主加附工况下确定纵向弯矩与纵向弹簧刚度之间的函数关系；基于所述纵向弯矩与纵向弹簧刚度之间的函数关系确定边塔桩基桩底反力与纵向弹簧刚度之间的函数关系；基于所述边塔桩基桩底反力与纵向弹簧刚度之间的函数关系确定纵向弹簧刚度最优值；将所述纵向弹簧刚度最优值代入基本模型计算中塔桩基桩底反力值；若所述中塔桩基反力值小于第一边界条件下基本模型对应的初始中塔桩基桩底反力值，则优化中塔塔底的基础规模。
一些实施例中，所述以主梁在边塔处纵向弹簧约束为第二边界条件在所述基本模型中获取第二边界条件下的纵向弹簧刚度初始值，包括：在主梁跨中处施加单位水平力，记为P；所述纵向弹簧刚度初始值记为k 0；根据公式k 0＝P/(10*δ)计算所述k 0，其中，δ为主梁在中塔纵向固定约束处的位移。
一些实施例中，所述基于所述纵向弹簧刚度初始值分别在主力工况和主加附工况下确定纵向弯矩与纵向弹簧刚度之间的函数关系，包括：以所述纵向弹簧刚度初始值的不同倍数值为参数代入所述基本模型求得对应不同倍数值的计算结果；分别在主力工况和主加附工况下 对所述计算结果进行拟合得到的对应的纵向弯矩与纵向弹簧刚度之间的函数关系。
一些实施例中，所述基于所述纵向弹簧刚度初始值分别在主力工况和主加附工况下确定纵向弯矩与纵向弹簧刚度之间的函数关系，包括确定：主力工况下的边塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系；主力工况下的中塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系；主加附工况下的边塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系；主加附工况下的中塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系。
一些实施例中，所述基于所述纵向弯矩与纵向弹簧刚度之间的函数关系确定边塔桩基桩底反力与纵向弹簧刚度之间的函数关系，包括确定：主力工况下的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系；主加附工况下的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系。
一些实施例中，所述基于所述边塔桩基桩底反力与纵向弹簧刚度之间的函数关系确定纵向弹簧刚度最优值，包括：根据第一公式确定所述纵向弹簧刚度最优值；
所述第一公式为：
Figure PCTCN2021086371-appb-000001
其中，k为纵向弹簧刚度，N 1,主力(0)为主力工况下的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系N 1,主力(k)在k为0时的取值，N 1,主+附(k)为主加附工况下的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系，m1为主力工况的提高系数，m2为主加附工况的提高系数。
一些实施例中，在将所述纵向弹簧刚度最优值代入基本模型之前，对所述基本模型进行截面参数更新；所述截面参数更新包括：将所述纵向弹簧刚度最优值代入所述纵向弯矩与纵向弹簧刚度之间的函数关系中计算纵向弯矩内力值；根据所述纵向弯矩内力值调整边塔和中塔的截面纵向尺寸；将调整后的截面纵向尺寸输入基本模型进行更新。
一些实施例中，所述根据所述纵向弯矩内力值调整边塔和中塔的截面纵向尺寸，包括：将边塔和中塔的截面纵向尺寸调整为相同尺寸。一些实施例中，在所述优化中塔塔底的基础规模之后，包括：基于优化后的基础规模对基本模型进行更新；基于所述纵向弹簧刚度最优值和更新后的基本模型计算更新后的中塔桩基桩底反力值；若更新后的中塔桩基桩底反力值小于第一边界条件下基本模型对应的初始中塔桩基桩底反力值，则继续优化中塔塔底的基础规模。
一些实施例中，所述优化中塔塔底的基础规模包括：减少桩基的数量；缩减承台尺寸。
本发明提供的技术方案带来的有益效果包括：本发明实施例提供了一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，其中通过提供了一种目的明确、易于操作、效果明显的确定三塔斜拉桥塔纵向弹簧刚度最优值的方法，并通过纵向弹簧刚度最优值对基础规模进行优化。采用本发明可获得三塔斜拉桥塔梁间纵向约束刚度值的最优解，并最大程度优化主塔的基础规模。同时还能使边、中塔外观尺寸统一，保持结构景观一致性并增强结构的韵律感。解决了现有技术中采用试算方式计算纵向约束刚度值时存在费时费力的问题，以及由于所计算出的纵向约束刚度值不能保证是最优解，从而导致主塔基础规模还存在较大优化空间的问题。
附图说明
为了更清楚地说明本发明实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本发明实施例提供的一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法流程示意图；
图2为本发明实施例提供的一种三塔斜拉桥塔的结构示意图；
图3为本发明实施例提供的在第二边界条件下的三塔斜拉桥塔的结构示意图；
图4为本发明实施例提供的边塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系；
图5为本发明实施例提供的中塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系；
图6为本发明实施例提供的基于第一公式确定纵向弹簧刚度最优值的示意图；
图7为本发明实施例提供的基于纵向弹簧刚度最优值计算中塔桩基桩底反力值的示意图。
附图标记：1、主梁；2、中塔；3、边塔；4、纵向固定约束；5、纵向弹簧约束；6、基础；7、承台；8、桩基。
具体实施方式
为使本发明实施例的目的、技术方案和优点更加清楚，下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例是本发明的一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动的前提下所获得的所有其他实施例，都属于本发明保护的范围。
如图1所示，本发明实施例提供了一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，通过计算出纵向弹簧刚度最优值对中塔塔底的基础规模进行优化并实现最大程度优化中塔塔底的基础规模。具体的，包括步骤：
S10:以主梁在边塔处纵向自由伸缩为第一边界条件建立基本模型；
S20:以主梁在边塔处纵向弹簧约束为第二边界条件在所述基本模型中获取第二边界条件下的纵向弹簧刚度初始值；
S30:基于所述纵向弹簧刚度初始值分别在主力工况和主加附工况下确定纵向弯矩与纵向弹簧刚度之间的函数关系；
S40:基于所述纵向弯矩与纵向弹簧刚度之间的函数关系确定边塔桩基桩底反力与纵向弹簧刚度之间的函数关系；
S50:基于所述边塔桩基桩底反力与纵向弹簧刚度之间的函数关系确定纵向弹簧刚度最优值；
S60:将所述纵向弹簧刚度最优值代入基本模型计算中塔桩基桩底反力值；
S70:若所述中塔桩基反力值小于第一边界条件下基本模型对应的初始中塔桩基桩底反力值，则优化中塔塔底的基础规模。
需要说明的是，所述三塔斜拉桥塔的桥塔基础都为软弱地基处的群桩基础，桩基受力模式为摩擦桩形式，且边塔、中塔桩基类型为相同直径桩基础。
需要说明的是，在步骤S10中建立基本模型，是以主梁在中塔处纵向固定为前提。边塔处纵向自由伸缩可以理解为此时边塔处塔梁间的纵向约束刚度为0，即以k表示纵向约束刚度(或后文中提到的纵向弹簧刚度)，则此时k＝0。
步骤S10还包括对所建立的基本模型进行有限元分析，确定所述基本模型所对应结构的基本规模和尺寸，包括：边塔和中塔的截面纵向尺寸、边塔和中塔的承台尺寸以及桩基础数量。
需要说明的是，在第一边界条件下的基本模型中，由于主梁在中塔处纵向固定、在边塔处纵向自由活动，此时边塔塔底的纵向弯矩远小于中塔塔底的纵向弯矩，因此设计时边塔的主塔纵向尺寸小于中塔纵向尺寸；相同地质情况下，边塔塔底的桩基础规模要小于中塔塔底的桩基础规模，即边塔塔底的桩基数量小于中塔塔底的桩基数量，边塔塔底承台结构尺寸也小于中塔塔底承台结构尺寸。
可以理解的是，步骤S20为了对边塔处的纵向约束刚度进行计算， 将步骤S10中的第一边界条件由纵向自由伸缩调整为纵向弹簧约束。其中纵向弹簧刚度初始值可基于基本模型以及设定的弹簧约束条件计算得到。
可优选地，确定纵向弹簧刚度初始值的具体步骤包括：
S201：在主梁跨中处施加单位水平力，记为P；
S202：所述纵向弹簧刚度初始值记为k 0；
S203：根据公式k 0＝P/(10*δ)计算所述k 0，其中，δ为主梁在中塔纵向固定约束处的位移。
需要说明的是，步骤S30中主力工况和主加附工况分别对应不同荷载条件下引起塔底纵向弯矩的情况。一般情况下，主力工况是指活载引起塔底纵向弯矩的情况，主加附工况是指主力工况与附加力工况同时作用的情况，其中附加力工况是指有附加力引起塔底纵向弯矩的情况，而所述附加力包括风荷载、温度荷载以及制动力。
可以理解的是，步骤S30与步骤S40中所述的函数关系，是在基本模型中基于纵向弹簧刚度初始值以及不同的工况条件下可以通过数值方法拟合而得到的。
可以理解的是，步骤S50中所述的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系是在主力工况下和主加附工况下的函数关系。基于两种不同工况下的函数关系的图形数据分析可以确定出纵向弹簧刚度最优值。
可以理解的是，步骤S70中所述的第一边界条件下基本模型对应的初始中塔桩基桩底反力值是通过将边塔处塔梁间的纵向约束刚度为0的边界条件代入基本模型中所计算得到的中塔桩基桩底反力值。对中塔塔底的基础规模进行优化的前提条件是中塔桩基反力值小于第一边界条件下基本模型对应的初始中塔桩基桩底反力值。
本实施例中通过建立基本模型，并调整第一边界条件为第二边界条件，以此确定三塔斜拉桥塔纵向弹簧刚度最优值，该方法目的明确、 易于操作、效果明显。通过纵向弹簧刚度最优值对基础规模进行优化，可有效减少中塔桩基规模，降低工程造价。
在一些实施例中，步骤S30包括：
S301：以所述纵向弹簧刚度初始值的不同倍数值为参数代入所述基本模型求得对应不同倍数值的计算结果；
S302：分别在主力工况和主加附工况下对所述计算结果进行拟合得到的对应的纵向弯矩与纵向弹簧刚度之间的函数关系。
需要说明的是，在步骤S301中，参数可以表示为N k 0，其中N为大于零的整数，k 0为纵向弹簧刚度初始值。参数可以优选为{k 0,2k 0,3k 0,10k 0}。
如图4、5所示，在一些实施例中，在步骤S30和S40中所述的函数关系包括：
主力工况下的边塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系，记为M 1,主力(k)；
主力工况下的中塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系，记为M 2,主力(k)；
主加附工况下的边塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系，记为M 1,主+附(k)；
主加附工况下的边塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系，记为M 2,主+附(k)；
其中k为纵向弹簧刚度。
如图4、5所示，主力工况下的边塔塔底纵向弯矩M 1,主力(k)、主力工况和主加附工况下的中塔塔底纵向弯矩M 2,主力(k)和M 2,主+附(k)为纵向弹簧刚度k的减函数，主加附工况下的边塔塔底纵向弯矩M 1,主+附(k)为纵向弹簧刚度k的增函数。
如图6所示，在一些实施例中，步骤S50所述的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系包括：
主力工况下的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系，记为N 1,主力(k)，
主加附工况下的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系，记为N 1,主+附(k)。
如图6所示，主力工况下的边塔桩基桩底反力N 1,主力(k)为纵向弹簧刚度k的减函数，主加附工况下的边塔桩基桩底反力N 1,主+附(k)为纵向弹簧刚度k的增函数。
如图6所示，在一些实施例中，步骤S50包括：根据第一公式确定所述纵向弹簧刚度最优值，
第一公式为：
Figure PCTCN2021086371-appb-000002
其中，k为纵向弹簧刚度，N 1,主力(0)为主力工况下的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系N 1,主力(k)在k为0时的取值，N 1,主+附(k)为主加附工况下的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系，m1为主力工况的提高系数，m2为主加附工况的提高系数。图5中的k’即为纵向弹簧刚度最优值。可优选地，主力工况的提高系数m1＝1，主加附工况的提高系数m2＝1.2。
在一些实施例中，在步骤S60中将纵向弹簧刚度最优值代入基本模型之前，对基本模型进行截面参数更新；其中截面参数更新包括步骤：
S60a-1：将所述纵向弹簧刚度最优值代入所述纵向弯矩与纵向弹簧刚度之间的函数关系中计算纵向弯矩内力值；
S60a-2：根据所述纵向弯矩内力值调整边塔和中塔的截面纵向尺寸；
S60a-3：将调整后的截面纵向尺寸输入基本模型进行更新。
可优选地，在步骤S60a-2中，可将边塔和中塔的截面纵向尺寸调整为相同尺寸。具体的，将纵向弹簧刚度最优值 k’代入对应函数关系式中，求得的主加附工况下边、中塔塔底纵向弯矩基本相同，即 M 1,主+附(k’)≈M 2,主+附(k’)，其特征在于，边、中塔纵向截面尺寸主要由主加附工况下塔底纵向弯矩M i,附加力确定；i＝1，表示边塔；i＝2，表示中塔。边、中塔塔形一致，横向受力情况相同，边、中塔截面的横向尺寸相同。可实现将边塔3、中塔2外观尺寸进行统一，结构景观一致性和韵律感最强。本实施例中通过对基本模型进行截面参数更新实现了对基本模型的进一步优化，从而使后续计算可基于优化后的基本模型进行，提高了优化的精度。
在一些实施例中，在步骤S70中优化中塔塔底的基础规模之后，还包括步骤：
S70b-1：基于优化后的基础规模对基本模型进行更新；
S70b-2：基于所述纵向弹簧刚度最优值和更新后的基本模型计算更新后的中塔桩基桩底反力值；
S70b-3：若更新后的中塔桩基桩底反力值小于第一边界条件下基本模型对应的初始中塔桩基桩底反力值，则继续优化中塔塔底的基础规模。
可以理解的是，当中塔桩基桩底反力值小于第一边界条件下基本模型对应的初始中塔桩基桩底反力值时，不仅对中塔塔底的基础规模进行优化，同时还根据优化后的基础规模调整基本模型，进一步对基本模型进行优化，从而使每一次计算得到的中塔桩基桩底反力值都是基于更新后的基本模型，进一步提高了整体优化精度。如此多次循环更新和优化后，可以使基础规模的优化达到最大程度。
若边塔底和中塔底工程地质情况相同，则优化基础规模时中塔塔底的基础规模可缩减至和边塔塔底的基础规模相同。
在一些实施例中，优化中塔塔底的基础规模包括：减少桩基数以及缩减承台尺寸。
在一个具体的实施例中，如图2所示的三塔斜拉桥塔，该桥为软弱地基上的桥梁，边塔3和中塔2的基础6采用的是承台7加桩基8 的方案。由于三塔斜拉桥结构受力特点的原因，中塔2结构纵向尺寸偏大，中塔2塔顶至塔底纵向尺寸为8m～13m；边塔3塔顶至塔底纵向尺寸为8m～10m；中塔2的基础6，即承台7和桩基8，要明显比边塔1的基础6规模大。边塔3的承台7尺寸为71×36m；桩基8为52根直径2.5m的桩基。中塔2的承台7尺寸为74×39m；桩基8为60根直径2.5m的桩基。
对如图1所示的三塔斜拉桥塔进行基础规模的优化，首先如图2所示，以主梁1在中塔2处设置纵向固定约束4、在边塔3处纵向自由伸缩为边界条件建立基本模型，进行有限元分析，确定结构的基本规模和尺寸，此时相当于边塔3处塔梁间纵向约束刚度k＝0；然后如图3所示，将基本模型中主梁1在边塔3处的纵向约束条件由纵向自由(k＝0)调整为纵向弹簧约束5(k＞0)；在基本模型中，在主梁1跨中处施加单位水平力P＝10000kN，求得主梁在中塔纵向固定约束处的位移δ＝0.0454m，则纵向弹簧约束5的刚度初值拟定为k 0＝P/(10*δ)＝22026kN/m；在计算模型中，边塔处的纵向弹簧刚度取不同值分别代入计算，k＝{22026,44052,66078,220264}；然后将计算结果值采用数值方法进行拟合，分别拟合出主力工况和主加附工况下，边塔3塔底纵向弯矩与纵向弹簧刚度k的函数关系，记为M 1,主力(k)和M 1,主+附(k)，如图4所示；以及中塔2塔底纵向弯矩与纵向弹簧刚度k的函数关系，记为M 2,主力(k)和M 2,主+附(k)，如图5所示；进而由相应的边塔3塔底纵向弯矩M 1,主力(k)和M 1,主+附(k)，求得边塔3处桩基础8的桩底反力与纵向弹簧刚度k的函数关系N 1,主力(k)和N 1,主+附(k)；定义主力工况的提高系数m1＝1和主加附工况的提高系数m2＝1.2，根据
函数关系式
Figure PCTCN2021086371-appb-000003
和
Figure PCTCN2021086371-appb-000004
进行图形数据分析，如图6所示，求得纵向弹簧刚度最优值k’＝37500,k’满足
Figure PCTCN2021086371-appb-000005
进一步将纵向弹簧刚度最优值k’代入对应函数关系式中，求得边 塔塔底纵向弯矩M 1,主力(37500)和M 1,主+附(37500)及中塔塔底纵向弯矩M 2,主力(37500)和M 2,主+附(37500)，根据求得的纵向弯矩内力值调整对应的边塔3和中塔2的截面纵向尺寸，可优选地将边塔3和中塔2的截面纵向尺寸调整为相同尺寸，即塔顶至塔底的纵向尺寸统一为8m～11.5m；之后按照调整后的边塔3、中塔2截面更新基本模型，并将塔梁处的纵向边界条件设定为边塔3处纵向弹簧刚度为k’＝37500，中塔2处主梁1设置纵向固定约束4，经有限元分析计算得到的优化后的中塔塔底纵向弯矩，记为M’ 2,主力(37500)和M’ 2,主+附(37500)，进一步求得中塔处桩基桩底反力，记为N’ 2,主力(37500)和N’ 2,主+附(37500)；此时计算所得的桩底反力N’ 2,主力(37500)和N’ 2,主+附(37500)小于原基本模型中设计的桩底反力N 2,主力(0)和N 2,主+附(0)，如图7所示；因此，可对桩基础规模进行优化，包括减少桩基数量和承台尺寸。再根据优化后的基础规模更新基本模型，并再次将塔梁处的纵向边界条件设定为边塔3处纵向弹簧刚度为k’＝37500，中塔2处主梁1设置纵向固定约束4，通过有限元分析计算新的中塔处桩基桩底反力，若仍然小于原基本模型中设计的桩底反力N 2,主力(0)和N 2,主+附(0)则继续进行基础规模，直到新计算出的中塔处桩基桩底反力等于原基本模型中设计的桩底反力N 2,主力(0)和N 2,主+附(0)停止优化。如此反复可良性循环求得最小的承台尺寸及最少的桩基数量。
本实施例中边塔3底和中塔2底工程地质情况相同，则优化基础规模时中塔2塔底桩基础8规模可缩减至和边塔3塔底桩基础8的规模相同，即桩数保持一致，皆采用52根直径2.5的桩基。且承台尺寸也相同，皆为71×36m。根据有限元模型计算结果数据的对比，采用本发明确定的三塔斜拉桥塔梁间纵向约束刚度及优化基础规模的方法，在不增加边塔3基础规模的前提下，可使中塔2塔底纵向弯矩降低21％、基础规模减少17％，可见采用本发明方案能最优化地降 低塔根纵向弯矩及减少桥塔和桥塔基础6的设计难度和规模。
本实施例提供了一种目的明确、易于操作、效果明显的确定三塔斜拉桥塔梁纵向约束刚度及优化基础规模的方法，获得了纵向弹簧刚度值的最优解，在控制边塔3基础6规模最小的基础上，最大程度优化了中塔2的基础6规模。另外边塔3、中塔2外观尺寸进行统一，结构景观一致性和韵律感最强。
在本发明的描述中，需要说明的是，术语“上”、“下”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本发明中的具体含义。
需要说明的是，在本发明中，诸如“第一”和“第二”等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的过程、方法、物品或者设备中还存在另外的相同要素。
以上所述仅是本发明的具体实施方式，使本领域技术人员能够理 解或实现本发明。对这些实施例的多种修改对本领域的技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本发明的精神或范围的情况下，在其它实施例中实现。因此，本发明将不会被限制于本文所示的这些实施例，而是要符合与本文所申请的原理和新颖特点相一致的最宽的范围。

Claims (10)

  1. 一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，其特征在于，其包括：
    以主梁在边塔处纵向自由伸缩为第一边界条件建立基本模型；
    以主梁在边塔处纵向弹簧约束为第二边界条件在所述基本模型中获取第二边界条件下的纵向弹簧刚度初始值；
    基于所述纵向弹簧刚度初始值分别在主力工况和主加附工况下确定纵向弯矩与纵向弹簧刚度之间的函数关系；
    基于所述纵向弯矩与纵向弹簧刚度之间的函数关系确定边塔桩基桩底反力与纵向弹簧刚度之间的函数关系；
    基于所述边塔桩基桩底反力与纵向弹簧刚度之间的函数关系确定纵向弹簧刚度最优值；
    将所述纵向弹簧刚度最优值代入基本模型计算中塔桩基桩底反力值；
    若所述中塔桩基反力值小于第一边界条件下基本模型对应的初始中塔桩基桩底反力值，则优化中塔塔底的基础规模。
  2. 如权利要求1所述的一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，其特征在于，所述以主梁在边塔处纵向弹簧约束为第二边界条件在所述基本模型中获取第二边界条件下的纵向弹簧刚度初始值，包括：
    在主梁跨中处施加单位水平力，记为P；
    所述纵向弹簧刚度初始值记为k 0；
    根据公式k 0＝P/(10*δ)计算所述k 0，其中，δ为主梁在中塔纵向固定约束处的位移。
  3. 如权利要求1所述的一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，其特征在于，所述基于所述纵向弹簧刚度初始值分别在主力工况和主加附工况下确定纵向弯矩与纵向弹簧刚度之间的函数关系，包括：
    以所述纵向弹簧刚度初始值的不同倍数值为参数代入所述基本模型求得对应不同倍数值的计算结果；
    分别在主力工况和主加附工况下对所述计算结果进行拟合得到的对应的纵向弯矩与纵向弹簧刚度之间的函数关系。
  4. 如权利要求1所述的一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，其特征在于，所述基于所述纵向弹簧刚度初始值分别在主力工况和主加附工况下确定纵向弯矩与纵向弹簧刚度之间的函数关系，包括确定：
    主力工况下的边塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系；
    主力工况下的中塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系；
    主加附工况下的边塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系；
    主加附工况下的中塔塔底纵向弯矩与纵向弹簧刚度之间的函数关系。
  5. 如权利要求1所述的一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，其特征在于，所述基于所述纵向弯矩与纵向弹簧刚度之间的函数关系确定边塔桩基桩底反力与纵向弹簧刚度之间的函数关系，包括确定：
    主力工况下的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系；
    主加附工况下的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系。
  6. 如权利要求5所述的一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，其特征在于，所述基于所述边塔桩基桩底反力与纵向弹簧刚度之间的函数关系确定纵向弹簧刚度最优值，包括：
    根据第一公式确定所述纵向弹簧刚度最优值；
    所述第一公式为：
    Figure PCTCN2021086371-appb-100001
    其中，k为纵向弹簧刚度，N 1,主力(0)为主力工况下的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系N 1,主力(k)在k为0时的取值，N 1,主+附(k)为主加附工况下的边塔桩基桩底反力与纵向弹簧刚度之间的函数关系，m1为主力工况的提高系数，m2为主加附工况的提高系数。
  7. 如权利要求1所述的一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，其特征在于，在将所述纵向弹簧刚度最优值代入基本模型之前，对所述基本模型进行截面参数更新；
    所述截面参数更新包括：
    将所述纵向弹簧刚度最优值代入所述纵向弯矩与纵向弹簧刚度之间的函数关系中计算纵向弯矩内力值；
    根据所述纵向弯矩内力值调整边塔和中塔的截面纵向尺寸；
    将调整后的截面纵向尺寸输入基本模型进行更新。
  8. 如权利要求7所述的一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，其特征在于，
    所述根据所述纵向弯矩内力值调整边塔和中塔的截面纵向尺寸，包括：
    将边塔和中塔的截面纵向尺寸调整为相同尺寸。
  9. 如权利要求1所述的一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，其特征在于，在所述优化中塔塔底的基础规模之后，包括：
    基于优化后的基础规模对基本模型进行更新；
    基于所述纵向弹簧刚度最优值和更新后的基本模型计算更新后的中塔桩基桩底反力值；
    若更新后的中塔桩基桩底反力值小于第一边界条件下基本模型对应的初始中塔桩基桩底反力值，则继续优化中塔塔底的基础规模。
  10. 如权利要求1所述的一种确定三塔斜拉桥塔梁纵向约束刚度及优化基础的方法，其特征在于，所述优化中塔塔底的基础规模包括：
    减少桩基的数量；
    缩减承台尺寸。
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