Method and system for evaluating the bearing capacity of the lower part of scour-damaged bridges under multiple loads

Abstract

The present invention discloses a method and system for assessing the bearing capacity of the substructure of a scour-damaged bridge under multiple loads. The method comprises: constructing a pier-cap-pile-soil system model; introducing vehicle load, flood load, additional bending moment at the pier top, bridge scour depth, and pier submergence depth as working conditions into the system model to obtain a mechanical model; calculating the total potential energy function of the system, establishing a horizontal displacement curve function of the system containing undetermined parameters, and setting the system's boundary conditions; constructing a linear algebraic equation for the undetermined parameters based on the principle of stationary potential energy; solving the undetermined parameters to obtain pier top displacement; calculating the pier top drift rate, which is used to assess the substructure bearing capacity of the bridge; and constructing a substructure bearing capacity assessment model with inputs of working condition parameters affecting the substructure bearing capacity of the bridge and outputs including pier top displacement and pier top drift rate. The present invention enables rapid and accurate assessment of the substructure bearing capacity of a bridge under the combined action of flood and vehicle loads.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge bearing capacity assessment, and in particular to a method and system for assessing the bearing capacity of the lower portion of a scour-damaged bridge subjected to multiple loads. Background Art

[0002] The bearing capacity of a bridge is a key indicator for measuring its safety. Under the concurrent conditions of scour damage, flooding can significantly reduce the bearing capacity of the bridge structure. As the main load-bearing component of a bridge, small and medium-span bridges across rivers and streams are extremely vulnerable to danger when subjected to multiple loads such as flood scour. In the worst case, the bridge may lose soil support and weaken the bearing capacity of the foundation, or even collapse. This combined effect of multiple loads creates a more complex and difficult-to-assess load environment for the bridge substructure, making assessment and protection work extremely challenging. Domestic and foreign scholars have conducted research on the bearing capacity of pile foundations under multiple loads.

[0003] For example, the paper "Analysis of Scour Stability of Bridge Pier Foundations under Anisotropic Soils," published in Sichuan Architecture, proposes a foundation model based on a transversely isotropic constitutive relationship, taking into account the transversely isotropic and anisotropic properties of the bridge foundation rock. This paper systematically analyzes the settlement and stability of bridge pier foundations under varying degrees of scour. Using the least-squares curve fitting method, a relationship between the horizontal displacement of the pier top and the scour percentage was established, and criteria for determining the ultimate scour percentage were proposed.

[0004] For example, the paper "Finite Element Analysis of the Effects of Scour on Bridge Pier Stability" (Liang Kai et al.) published in Rock and Soil Mechanics systematically calculates and analyzes the compressive stresses and pier top displacements in pier foundations under varying degrees of scour, based on the actual engineering context of the Zishui Bridge on the Hunan-Guizhou Railway. The paper proposes simulating the hollowing process at the base of the foundation by varying the base support method. The paper analyzes the ultimate hollowing area when the maximum base compressive stress equals the allowable compressive stress, and compares the critical scour conditions that result in severe foundation deformation and stress when considering the maximum lateral, longitudinal, and vertical displacements of the pier top.

[0005] For example, in the paper "Bearing Capacity Analysis of VT Combined Loaded Piles in Gibson Foundation" published in the journal "Engineering Mechanics", the soil around the pile is regarded as a Gibson foundation in which the shear modulus varies linearly with depth. The displacement incompatibility of the pile-soil contact surface is considered, and the analytical solutions of the internal forces and displacements of the pile body at different stress stages are derived. A stress analysis method for VT combined loaded piles based on the shear displacement method and load transfer function is proposed, which takes into account vertical forces and torques.

[0006] For example, in the paper "Analysis of the stress and deformation of a single pile under axial transverse load based on the energy method" published in the journal "Hydrogeology and Engineering Geology", an energy equation for the pile and the soil around the pile was established, and through the coordination of pile-soil deformation and the principle of minimum potential energy, the differential equation governing the deformation of a single pile under axial transverse load was derived, and the analytical solution was obtained using the power series method.

[0007] For example, in the paper "Theoretical Analysis of the Bearing Characteristics of Pile Groups Under Inclined Loads," published in the journal Rock and Soil Mechanics, differential equations for the deflection of the free and embedded sections of the pile shaft were established. Incorporating the P-Δ effect, the shear displacement method was used to analyze the pile-soil relationship under vertical load. An iterative method was used to calculate the load-displacement curve and the bending moment distribution of the pile shaft. A bearing capacity analysis method based on the combination of the Py curve method for pile groups and the shear displacement method was proposed.

[0008] Scour damage can significantly impact the bearing capacity of bridges. Scour can alter the soil constraints surrounding piles, affecting the stiffness of the bridge structure and creating a more complex and difficult-to-assess load environment. Several researchers have conducted research on the bearing capacity of scour-damaged bridges under multiple loads, including numerical simulations and theoretical derivations.

[0009] For example, the paper "Experimental Study and Numerical Simulation of the Horizontal Bearing Characteristics of Single Pile Under Scour" published in the Journal of Hydraulic Engineering systematically studied the changes in the horizontal bearing capacity of single piles under different scour depths through a combination of indoor model tests and FLAC3D numerical simulations. The numerical simulation, modified by the experiments, further analyzed the effects of factors such as scour angle, pile top fixing method, and scour range on the horizontal bearing capacity of pile foundations.

[0010] For example, in the paper "Three-dimensional Differential Simulation and Calculation Analysis of the Influence of Soil Scour on Bridge Pile Foundations" published in the journal "Journal of Shandong University of Science and Technology (Natural Science Edition)", a three-dimensional finite difference mechanical model was established to analyze the influence of changes in pile foundation boundary conditions on pile stress and displacement under scouring, and the vertical and horizontal displacements and stresses of the pile foundation under the combined action of normal loads, ship collision loads and scouring were analyzed.

[0011] For example, the Chinese patent with publication number CN119397827A, entitled "A method for simulating flood scour damage for shallow-buried foundation bridges", realizes multi-field coupling simulation of flood, soil, heavy vehicle load and bridge structure by extracting scour depth, flow field and scour pit morphology, and proposes a bridge structure damage simulation method that integrates riverbed scour characteristic analysis, point cloud reverse engineering, fluid-solid coupling and multi-physics field finite element analysis.

[0012] For example, Chinese patent publication number CN113704859A, titled "A Method for Analyzing Concrete Bridge Flood Vulnerability Considering Pier Failure Modes," calculates the shear capacity of piers based on bridge structural parameters and reinforcement information. A numerical analysis model is then established to identify the flow forces and velocities at the piers' maximum load-bearing capacity. Monte Carlo simulations are then used to fit a bridge flood vulnerability curve.

[0013] In summary, research on the bearing capacity of bridge foundations covers aspects such as scour conditions, different soil parameters, and foundation forms. Existing studies have employed numerical simulation methods, theoretical derivation, and a combination of the two, revealing the impact of scour depth, soil properties, foundation stiffness, and other factors on bearing capacity changes. Furthermore, theoretical derivation provides a foundation for determining the ultimate limit state and failure mode of bearing capacity. However, existing studies have primarily focused on single-form loads, and the accuracy of their bearing capacity analysis and the efficiency of their bearing capacity assessment need to be improved. No studies of bridge foundation bearing capacity have simultaneously considered scour damage, actual vehicle loads, and extreme hydrological conditions. Therefore, there is an urgent need to develop methods and systems for assessing the bearing capacity of scour-damaged bridge substructures under multiple loads. Summary of the Invention

[0014] In view of the above problems, the present invention provides a method and system for evaluating the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads.

[0015] The technical solutions adopted by the present invention to solve the technical problems are as follows:

[0016] In a first aspect, the present invention provides a method for assessing the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads, comprising:

[0017] Construct a pier-cap-pile-soil system model for the substructure;

[0018] The vehicle load, flood load, additional bending moment on the pier top, bridge scour depth, and pier submergence depth are introduced as action conditions into the pier-cap-pile-soil system model to obtain a mechanical model of the pier-cap-pile-soil system.

[0019] Calculating the total potential energy function of the pier-cap-pile-soil system, establishing a horizontal displacement curve function of the pier-cap-pile-soil system, and setting boundary conditions of the pier-cap-pile-soil system, wherein the established horizontal displacement curve function includes undetermined parameters;

[0020] Based on the principle of stationary value of potential energy, a linear algebraic equation of the unknown parameters is constructed; the unknown parameters are solved to obtain the pier top displacement;

[0021] Calculating the pier top drift rate, which is used to assess the bearing capacity of the lower part of the bridge;

[0022] A substructure bearing capacity assessment model is constructed, wherein the input of the substructure bearing capacity assessment model is the working condition parameters that affect the bearing capacity of the substructure of the bridge, and the output includes the pier top displacement and the pier top drift rate.

[0023] In a preferred embodiment, the vehicle load is the vertical concentrated force acting on the pier top and the horizontal braking force acting on the pier top, and the flood load is the transverse bridge component and the longitudinal bridge component of the flood dynamic water pressure, and the flood dynamic water pressure is the flood dynamic water pressure in the form of a uniformly distributed load;

[0024] The transverse component of the flood dynamic pressure is expressed as:

[0025]

[0026] The longitudinal bridge component of the flood dynamic pressure is expressed as:

[0027]

[0028] in, It represents the time-averaged resistance per unit length of flood load in the transverse direction of the bridge. It represents the time-averaged resistance per unit length of flood load in the longitudinal direction of the bridge. represents the resistance coefficient per unit length, represents the water density, Indicates the area per unit length of the bridge perpendicular to the water flow direction, It represents the average flow velocity of the cross section. It indicates the incident angle of flood water relative to the transverse direction of the bridge pier.

[0029] In a preferred embodiment, the total potential energy function includes the bending strain energy of the pier-cap-pile-soil system , Strain energy of sliding bearing at top of pier , pile-soil spring strain energy , axial force work , the work done by the pier-cap-pile-soil system's own gravity , horizontal braking force and additional bending moment work at pier top , work done by dynamic water pressure .

[0030] In a preferred embodiment, the axial force work includes the vertical concentrated force work acting on the pier top in the vehicle load, the axial force equivalent to the superstructure acting on the pier top, and the axial force equivalent to the gravity of the cap acting on the pile top;

[0031] The horizontal braking force and the additional bending moment on the pier top do the work Expressed as:

[0032]

[0033] in, It represents the horizontal braking force acting on the pier top in the vehicle load. represents the displacement of the pier top, represents the additional bending moment at the pier top, Indicates the pier top angle;

[0034] The hydrodynamic pressure does work Expressed as:

[0035]

[0036] in, The time-averaged resistance component of the flood load acting on the length of the bridge pier is expressed as the longitudinal component of the bridge. The time-averaged resistance component of the flood load acting on the pile length is expressed as the longitudinal component of the bridge. represents the horizontal displacement curve function value, Indicates the height of the initial scour line from the pile top, represents the equivalent single pile length, Indicates the height of the water level from the pier top. Indicates the total height of the pier-cap-pile-soil system, Indicates the bridge scour depth.

[0037] In a preferred embodiment, the horizontal displacement curve function of the pier-cap-pile-soil system is established as:

[0038]

[0039] in, represents the horizontal displacement curve function value, as well as represents the undetermined parameters of the horizontal displacement curve function; Indicates the trial function number, a total of A test function, represents the axial coordinate of the pier-cap-pile-soil system, Indicates the total height of the pier-cap-pile-soil system.

[0040] In a preferred embodiment, the constraint conditions of the pier-cap-pile-soil system are that the pile bottom is hinged, the pier top is free, and the pier top bears the horizontal braking force of the vehicle load and the additional bending moment of the pier top; the boundary conditions include force boundary conditions and displacement boundary conditions, and the force boundary conditions are:

[0041]

[0042] in, represents the bending stiffness of the pier, represents the second-order derivative of the pier top displacement, represents the additional bending moment at the pier top, represents the third-order derivative of the pier top displacement, Indicates the horizontal braking force of the vehicle load on the pier top, represents the sliding bearing stiffness of the pier top bearing, represents the displacement of the pier top;

[0043] The displacement boundary condition is:

[0044]

[0045] in, represents the displacement of the pile bottom, represents the second-order derivative of pile bottom displacement.

[0046] In a preferred embodiment, the linear algebraic equation for the undetermined parameters is constructed based on the principle of stationary potential energy, which includes: taking the first-order variation of the total potential energy function to zero, and obtaining the partial differential equations of the undetermined parameters to obtain the linear algebraic equation ,in represents the stiffness matrix, represents the unknown parameter matrix, represents the equivalent load matrix.

[0047] In a preferred embodiment, when training the substructure bearing capacity assessment model, Latin hypercube sampling is performed on the operating parameters affecting the bearing capacity of the bridge substructure, and the substructure bearing capacity assessment model adopts an XGBoost machine learning regression model; when constructing the substructure bearing capacity assessment model, a nonlinear mapping relationship between the input operating parameters affecting the bearing capacity of the bridge substructure and the pier top displacement is established:

[0048]

[0049] in, represents a nonlinear function, Indicates the bridge scour depth, Indicates the depth of flooding, The axial force at the top of the pier, Indicates flood flow speed, Indicates the flood water incident angle, represents the additional bending moment at the pier top, Indicates the horizontal braking force of the vehicle load on the pier top.

[0050] In a preferred embodiment, the vehicle load is the vertical concentrated force acting on the pier top and the horizontal braking force acting on the pier top, and the horizontal braking force acting on the pier top is calculated as 10% of the total gravity of the vehicle uniformly distributed load within the loading length range.

[0051] In a second aspect, the present invention provides a system for assessing the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads, comprising:

[0052] The first model construction module is used to construct a pier-cap-pile-soil system model of the substructure, and is used to introduce vehicle load, flood load, additional bending moment at the pier top, bridge scour depth, and flood inundation depth as action conditions into the pier-cap-pile-soil system model to obtain a pier-cap-pile-soil system mechanical model;

[0053] a first calculation module, configured to calculate a total potential energy function of the pier-cap-pile-soil system, establish a horizontal displacement curve function of the pier-cap-pile-soil system, and set boundary conditions of the pier-cap-pile-soil system, wherein the established horizontal displacement curve function includes undetermined parameters;

[0054] The second calculation module is used to construct a linear algebraic equation of the undetermined parameters based on the principle of stationary value of potential energy; and is used to solve the undetermined parameters to obtain the pier top displacement;

[0055] A third calculation module is used to calculate the pier top drift rate, which is used to assess the bearing capacity of the lower part of the bridge;

[0056] The second model building module is used to build a substructure bearing capacity assessment model. The input of the substructure bearing capacity assessment model is the working condition parameters that affect the bearing capacity of the bridge substructure, and the output includes pier top displacement and pier top drift rate.

[0057] The present invention breaks through the limitations of traditional methods that only consider one or two loads. Based on bridge scour damage, the present invention introduces vehicle-flood effects, designs a specific processing method based on multiple loads according to all considered loads, establishes the total potential energy function of the structure under the combined action of loads, and solves the horizontal displacement curve function to determine the pier top displacement, so that the present invention can more accurately simulate the actual stress conditions of scour-damaged bridges and more accurately determine the bridge's bearing capacity. On this basis, a model of operating parameters and pier top displacement that affect the bearing capacity of the lower part of the bridge is designed and established, realizing a rapid assessment of the bearing capacity of the lower part of the scour-damaged bridge under the combined action of multiple loads. The drift rate, a normalized indicator, is introduced to intuitively reflect the relative deformation degree of the bridge pier under flood scour damage. The method and system for assessing the bearing capacity of the lower part of a scour-damaged bridge under the action of multiple loads of the present invention realizes a rapid and accurate assessment of the bearing capacity of the lower part of the bridge. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 A flow chart of the method for evaluating the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads provided by the present invention;

[0059] Figure 2 Schematic diagram of the pier-cap-pile-soil system model of the substructure;

[0060] Figure 3 This is a simplified mechanical model diagram of the pier-cap-pile-soil system under multiple combined loads;

[0061] Figure 4 Schematic diagram of the prediction effect of the XGBOOST model;

[0062] Figure 5 The framework diagram of the system for assessing the bearing capacity of the lower part of a scour-damaged bridge under multiple loads.

[0063] Figure 6 A schematic diagram of an electronic device. DETAILED DESCRIPTION

[0064] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0065] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0066] It should be noted that the technical solutions between the various embodiments can be combined with each other, and reference can be made to the specific descriptions of other embodiments. For example, the specific implementation process of the system can refer to the specific embodiments of the method. However, it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0067] Accurately determining the bearing capacity of a bridge is crucial for driving safety. Current methods for determining and assessing bearing capacity primarily rely on a single load, lacking in-depth consideration of the ultimate bearing capacity and failure modes of foundations under vehicle loads, flood loads, scour evolution, and their coupled effects. This leaves much to be desired in terms of reliability and processing efficiency. Consequently, effectively assessing the structural performance and driving safety of bridges subjected to scour damage, flooding, and vehicle loads has become a key issue. To address this, the present invention provides a method for assessing the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads.

[0068] See also Figure 1 , which is a flow chart of a method for assessing the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads, the method includes:

[0069] Construct a pier-cap-pile-soil system model for the substructure;

[0070] Applying vehicle load, flood load, additional bending moment on the pier top, bridge scour depth, and flood inundation depth to the pier-cap-pile-soil system model to obtain a mechanical model of the pier-cap-pile-soil system;

[0071] Calculating the total potential energy function of the pier-cap-pile-soil system, establishing a horizontal displacement curve function of the pier-cap-pile-soil system, and setting boundary conditions of the pier-cap-pile-soil system, wherein the established horizontal displacement curve function includes undetermined parameters;

[0072] Constructing a linear algebraic equation for the unknown parameters based on the principle of stationary value of potential energy; solving the unknown parameters to obtain the pier top displacement;

[0073] Calculating the pier top drift rate, which is used to assess the bearing capacity of the lower part of the bridge;

[0074] A substructure bearing capacity assessment model is constructed, wherein the input of the substructure bearing capacity assessment model is the working condition parameters affecting the bearing capacity of the substructure of the bridge, and the output is the pier top displacement and the pier top drift rate.

[0075] In the following examples, the evaluation method and its effects are described in detail.

[0076] Step S101: Construct a pier-cap-pile-soil system model of the substructure.

[0077] The data that needs to be obtained include the parameters of the bridge substructure. Here, in order to build the pier-cap-pile-soil system model, the data obtained include: pier height , equivalent single pile length , equivalent pile diameter , moment of inertia of pier , Equivalent single pile moment of inertia , elastic modulus of pier , pile elastic modulus , Bridge pier self-weight uniformly distributed load , Equivalent single pile self-weight uniformly distributed load , the axial force equivalent to the gravity of the bridge superstructure acting on the pier top , the axial force equivalent to the gravity of the cap acting on the pile top 、Soil The pier-cap-pile-soil system can be referred to as the system.

[0078] like Figure 2 As shown in the pier-cap-pile-soil system model, the geometric parameters and material parameters of the actual bridge pier are obtained; the equivalent single pile is equivalent to the pile group, and the equivalent single pile diameter is obtained by: equivalent to the static stiffness equivalence principle of the actual bridge pile group; the equivalent axial force of the cap gravity is obtained ; Obtain the equivalent axial force of the superstructure gravity . Figure 2 middle 、 are the stiffness of the bridge pier and the equivalent single pile respectively. The m value of the soil body under the pile-soil interaction is the commonly used m value in the Winkler foundation model. Law( Represents the foundation soil proportional coefficient) to simulate the pile-soil interaction. Based on the elastic foundation beam theory and Winkler hypothesis, the soil reaction force on the pile side is proportional to the lateral displacement of the pile body at that location. The pile body is divided into pile body units, corresponding to Soil layers, there are pile body unit nodes, Indicates the total number of pile body sub-unit nodes. In this paper, the definition Figure 2 The vertical direction, i.e. the axial direction of the system, is the x-axis direction, and the horizontal direction of the bridge is the y-axis direction. All represent the coordinates of the pile body subunit nodes, Indicates the The coordinates of the pile body unit nodes, Indicates the The node coordinates of the pile body unit and the soil resistance per unit length in each pile body unit are simplified Winkler foundation model The equivalent spring stiffness is:

[0079]

[0080] in, Indicates the number, , Indicates the The equivalent stiffness per unit length in a soil spring is understood to be that the pile-soil spring can be simulated by setting up a soil spring unit. Indicates the The foundation depth in pile subunits, Indicates the The proportional coefficient of the horizontal resistance coefficient of the soil foundation at each pile unit is: It represents the calculated width of the pile foundation, which is related to the pile diameter and pile cross-sectional shape.

[0081] Step S102: Obtain action parameters, and establish a simplified mechanical model of the pier-cap-pile-soil system under the combined action of multiple loads based on the obtained action parameters, also known as the mechanical model of the pier-cap-pile-soil system, which can be found in Figure 3 , Figure 3 O represents the coordinate origin.

[0082] The action parameters include vehicle load, flood load, additional bending moment on pier top, bridge scour depth Flood inundation depth , furthermore, it also includes the height of the initial scour line from the pile top , these action parameters are applied to the pier-cap-pile-soil system model to complete the establishment of a simplified mechanical model.

[0083] The vehicle load is considered as the vertical concentrated force acting on the pier top according to the specification and simplification principle. The horizontal braking force acting on the pier top is calculated based on 10% of the total gravity of the vehicle's uniformly distributed load within the loading length range.

[0084] The action of flood not only aggravates the scouring damage and weakens the soil restraint, thereby changing the boundary conditions, but also acts on the lower structure in the form of flood loads. The flood force can be divided into dynamic water pressure and hydrostatic pressure. Considering that the dynamic characteristics of floods have a greater impact on the lower bearing capacity, while the hydrostatic pressure has a smaller impact, the flood load is considered to be the flood dynamic water pressure, that is, the flood load is the flood dynamic water pressure. Notably, this embodiment takes into account that the flood force in actual working conditions does not act vertically on the bridge piers, and introduces the flood water flow incidence angle to improve the accuracy of the results. The flood load is the transverse bridge component of the flood dynamic water pressure The longitudinal component of the flood dynamic pressure The flood dynamic pressure is a uniformly distributed load. The flood load is applied to the pier-cap-pile-soil system model by applying the transverse and longitudinal components of the flood dynamic pressure to the pier-cap-pile-soil system model. The transverse component of the flood dynamic pressure is expressed as:

[0085]

[0086] The longitudinal bridge component of flood dynamic pressure is expressed as:

[0087]

[0088] in, is the time-averaged resistance per unit length of flood load in the transverse direction of the bridge, is the time-averaged resistance per unit length of flood load in the longitudinal direction of the bridge, is the resistance coefficient per unit length, is the water density, is the unit length area of ​​the bridge perpendicular to the water flow direction, is the average flow velocity of the cross section, It is the incident angle of flood water relative to the transverse direction of the bridge pier.

[0089] Step S103: Calculate the total potential energy function of the pier-cap-pile-soil system , set the horizontal displacement curve function of the system and set the boundary conditions of the system.

[0090] The total potential energy function includes the bending strain energy of the pier-cap-pile-soil system , Strain energy of sliding bearing at top of pier , pile-soil spring strain energy , axial force work , the system's own gravity does work , horizontal braking force and additional bending moment work on pier top , work done by dynamic water pressure Here, the total potential energy function The expression is:

[0091]

[0092] The bending strain energy of the pier-cap-pile-soil system Expressed as:

[0093]

[0094] in, Represents the second-order derivative of the horizontal displacement curve function; Indicates the bending stiffness of the pier; represents the flexural stiffness of the equivalent single pile; , which represents the total height of the pier-cap-pile-soil system.

[0095] The strain energy of the sliding bearing at the top of the pier Expressed as:

[0096]

[0097] in, is the sliding bearing stiffness of the pier top bearing, which is a fixed value. is the displacement of the pier top.

[0098] The pile-soil spring strain energy Expressed as:

[0099]

[0100] in, is the node spacing, For the above mentioned The equivalent stiffness per unit length of the soil spring is obtained from the Winkler foundation model in step S101. The equivalent spring stiffness calculation formula is obtained. Specifically, ,in, It is expressed as the actual pile-soil height after scour damage.

[0101] The axial force does work It includes the vertical concentrated force work acting on the pier top in vehicle load, the axial force of the superstructure acting equivalently on the pier top, and the axial force of the pedestal gravity acting equivalently on the pile top.

[0102]

[0103] in, is the equivalent total load acting on the superstructure, , is the vertical concentrated force of vehicle load.

[0104] The system's own gravity (system body force) does work Expressed as:

[0105]

[0106] in, is the first-order derivative of the horizontal displacement curve function, is the height coordinate in the system, that is, the vertical coordinate value at different heights in the system, that is, the distance from the bottom of the pile in the vertical direction.

[0107] The horizontal braking force and the additional bending moment on the pier top do the work Expressed as:

[0108]

[0109] in, is the horizontal braking force acting on the pier top in the vehicle load, is the additional bending moment at the pier top due to the displacement of the pier-cap-pile-soil system and the vertical load, is the displacement of the pier top, It is the corner of the pier top.

[0110] The hydrodynamic pressure does work Expressed as:

[0111]

[0112] in, is the time-averaged resistance of the flood load acting on the length of the bridge pier, is the longitudinal component of the bridge-direction dynamic water pressure acting on the bridge pier, is the time-averaged resistance component of the flood load acting on the pile length along the longitudinal direction of the bridge, according to calculate, is the horizontal displacement of the pier-cap-pile-soil system, is the height of the initial scour line from the pile top, is the equivalent single pile length, is the height from the water level to the pier top, is the total height of the substructure, i.e. the total height of the pier-cap-pile-soil system. is the bridge scour depth.

[0113] The horizontal displacement curve function of the pier-cap-pile-soil system is set as:

[0114]

[0115] in, represents the horizontal displacement curve function value, that is, the horizontal displacement of the pier-cap-pile-soil system. as well as are all unknown parameters of the horizontal displacement curve function of the system, and are the coefficients of the trial function; is the test function number, set A test function, is the axial coordinate of the pier-cap-pile-soil system.

[0116] The boundary conditions include force boundary conditions and displacement boundary conditions.

[0117] For the pier-cap-pile-soil system, the force boundary conditions are:

[0118]

[0119] in, is the second-order derivative of the pier top displacement, is the third-order derivative of the pier top displacement.

[0120] Assuming that the constraints of the pier-cap-pile-soil system are that the pile bottom is hinged, the pier top is free, and the pier top bears the horizontal braking force of the vehicle load and the additional bending moment at the pier top, the displacement boundary condition for the pier-cap-pile-soil system is:

[0121]

[0122] in, is the pile bottom displacement, is the second-order derivative of pile bottom displacement.

[0123] It can be understood that, in this embodiment, the established horizontal displacement curve function satisfies the constraint condition.

[0124] Step S104: According to the total potential energy calculated in step S103, the horizontal displacement curve function is substituted into the total potential energy function, and then the linear algebraic equations of all the undetermined parameters in the horizontal displacement curve function are constructed based on the principle of stationary value of potential energy. The linear algebraic equations of the undetermined parameters and the boundary conditions are used to solve the linear algebraic equations, that is, to solve the undetermined parameters. After the undetermined parameters are solved, they are substituted into the horizontal displacement curve function to obtain the expression of the pier top displacement.

[0125] Specifically, after the total potential energy of the pier-cap-pile-soil system is calculated in step S103, the horizontal displacement curve function constructed in step S103 is substituted into the total potential energy function. According to the stationary value principle of potential energy, the first-order variation of the total potential energy is taken to be zero, and a set of equations for the undetermined parameters is obtained:

[0126]

[0127] Right now

[0128] After organizing these equations about the unknown parameters, they can be written in the form of linear algebraic equations, namely:

[0129]

[0130] in is the stiffness matrix, matrix; is the unknown parameter matrix, matrix, is the equivalent load matrix, matrix.

[0131] Here, the is a symmetric matrix, and its specific expression is as follows:

[0132]

[0133] Among them, the element in row 1 and column 1 The expression is:

[0134]

[0135] The first row element or the first column element satisfies , whose expression is:

[0136]

[0137] Non-diagonal items in non-first row (non-first column) , whose expression is:

[0138]

[0139] Non-first row main diagonal elements The expression is:

[0140]

[0141] in, The value range of is [1, ], and it is an integer.

[0142] described Expressed as:

[0143]

[0144] described It can be expressed as:

[0145]

[0146]

[0147]

[0148] in, and All are equivalent load items. , represents the actual pile-soil height after scour damage, is the resistance coefficient per unit length of the pier, is the resistance coefficient per unit length of the pile, is the flow area per unit length of the pier perpendicular to the water flow direction, are the flow area per unit length of the pile perpendicular to the water flow direction, is the average flow velocity of the water in the pier section, is the average flow velocity of water in the pile section.

[0149] Solve the matrix to get the unknown parameters as well as , we get the horizontal displacement curve function expression, where the pier top displacement can be expressed as (the pier top is ):

[0150]

[0151] Step S105: Calculate the pier top drift rate, which is used to assess the bearing capacity of the lower part of the bridge.

[0152] The pier top drift rate is determined by the ratio of the pier top displacement to the total height of the pier-cap-pile-soil system. The pier top drift rate provides a clear understanding of the bridge's substructure bearing capacity.

[0153] Drift rate of load-bearing capacity assessment index It can be expressed as:

[0154]

[0155] The obtained pier top displacement can, to a certain extent, reflect the stress and deformation state of the substructure when a scour-damaged bridge is subjected to the combined action of multiple loads. However, due to the differences in different bridge structures and sizes, it is difficult to comprehensively evaluate its bearing capacity using only the pier top displacement value as a criterion. Therefore, this embodiment introduces a normalized indicator called drift rate. By ratioing the pier top displacement with the pier height, the influence of different pier heights on the evaluation results is eliminated, thereby establishing a more universal substructure bearing capacity assessment method. The drift rate can intuitively reflect the relative deformation degree of the pier under flood scour damage. When it exceeds a specific critical value, it indicates that the pier is close to the limit state of horizontal bearing capacity, indicating that the bridge structure is at a high risk of failure.

[0156] In this embodiment, an exemplary reference standard is set. When , the corresponding bridge structure is severely damaged and collapsed; When , the bridge structure is moderately damaged. When , the corresponding bridge structure is slightly damaged. When , the corresponding bridge structure is not damaged.

[0157] Step S106: Construct a substructure bearing capacity assessment model.

[0158] A model for assessing the bearing capacity of the substructure under the combined action of multiple loads was constructed. Specifically, using LHS bulk sampling and machine learning methods, a regression model was constructed that correlated the operating parameters that affect the bearing capacity of the bridge substructure (called action parameters or operating parameters) with the substructure bearing capacity.

[0159] Based on the evaluation model, the bearing capacity of the bridge substructure can be evaluated efficiently. In this embodiment, a regression model of key action parameters and pier top displacement is constructed. In this step, the Latin Hypercube (LHS) sampling method is first used according to existing specifications to sample the key parameters affecting the bearing capacity under the combined action of multiple loads. The key working condition parameters affecting the bearing capacity of the bridge substructure include flood inundation depth. , axial force at pier top , flood flow speed , flood water incident angle , additional bending moment at pier top , horizontal braking force of vehicle load on pier top , bridge scour depth , generating a large number of sample points to efficiently cover a variety of operating conditions. Each sample point represents a combination of operating parameters of the bridge substructure under the combined action of multiple loads and different scour damage scenarios. The parameters illustrated here were determined based on sensitivity analysis in this embodiment.

[0160] The above steps S101 to S104 are programmed using MATLAB to achieve batch and rapid calculation of pier top displacements under different bridge working conditions.

[0161] On this basis, using the aforementioned large-scale sample data, we employed the integrated machine learning regression algorithm XGBoost (eXtreme GradientBoosting, an optimized distributed gradient boosting library) to train an XGBoost regression model with multiple inputs (multiple operating parameters that affect the bridge's lower load-bearing capacity) and a single output (the pier top displacement). Using the XGBoost regression model, we set hyperparameters and then performed a fit on the training set, establishing a nonlinear mapping relationship between the input operating parameters and the pier top displacement:

[0162]

[0163] in, The depth of flooding, is the axial force at the pier top, is the flood flow velocity, is the flood water incident angle, Additional bending moment for pier top, is the horizontal braking force of the vehicle load on the pier top, is the bridge scour depth, represents a nonlinear function.

[0164] Using the test set data, calculate the root mean square error (RMSE) and determination coefficient ( ), to test the prediction accuracy of the trained model, the root mean square error (RMSE) of this regression model is 0.0395, and the determination coefficient ( ) is 0.9917. Figure 4 As shown, it can be seen that the data (blue dots represent the scatter distribution of the actual and predicted values ​​of the pier top displacement) closely fit the diagonal line (the red dotted line represents the ideal fitting relationship), indicating that the model's predicted values ​​of the pier top displacement are in good agreement with the actual values ​​of the pier top displacement, demonstrating that this method successfully and quickly achieves accurate assessment of the bearing capacity of the lower part of the scour-damaged bridge under the combined action of multiple loads.

[0165] In one embodiment, the evaluation method can be understood as: constructing the substructure bearing capacity evaluation model is to construct a model framework, and based on the framework, the calculation process of steps S101 to S105 is performed.

[0166] The output of the evaluation model includes a pier top drift rate. The evaluation model can calculate the pier top drift rate according to the pier top displacement and output the pier top drift rate.

[0167] Furthermore, in one embodiment, the output of the assessment model may also include a bridge substructure load-bearing assessment result presented in text form, and the bridge substructure load-bearing assessment result presented in text form is determined based on the pier top drift rate.

[0168] As an example and not a limitation, the evaluation model includes a classification unit, which directly classifies the bridge substructure load-bearing evaluation results in text form according to the numerical value of the pier top drift rate. The evaluation model output includes the bridge substructure load-bearing evaluation results in text form. As an example, When the bridge structure is classified as severely damaged and collapsed, the output is similar to the text expressing this meaning, "The bridge structure is severely damaged and collapsed". When the bridge structure is classified as moderately damaged, When the bridge structure is classified as slightly damaged, When , the bridge structure is classified as non-damaged.

[0169] It should be understood that the method further includes the step of evaluating the bearing capacity of the lower portion of the bridge using the lower structure bearing capacity assessment model.

[0170] This embodiment provides a rapid assessment method for the bearing capacity of the substructure of scour-damaged bridges under the combined action of multiple loads. This method overcomes the limitations of traditional methods that only consider one or two loads. Based on bridge scour damage, this embodiment introduces vehicle-flood coupling and, based on all considered loads, designs a specific method for handling the combined action of multiple loads (including flood and vehicle). This method establishes a total potential energy function for the structure under the combined action of these loads and solves the horizontal displacement curve function to determine the pier top displacement. This allows this embodiment to more accurately simulate the actual stress conditions of scour-damaged bridges and more precisely determine their bearing capacity. Furthermore, this embodiment employs a machine learning-based driving method to establish a model of operating parameters and pier top displacement that influence the bearing capacity of the bridge substructure. The assessment model outputs include pier top displacement and pier top drift rate, enabling rapid assessment of the bearing capacity of scour-damaged bridges under the combined action of multiple loads. The pier top drift rate, a normalized indicator, is introduced to intuitively reflect the relative deformation of the piers under flood scour damage.

[0171] Specifically, this embodiment first establishes a pier-cap-pile-soil system for the substructure after scour damage. It innovatively incorporates flood loads and vehicle loads (including vertical concentrated forces and horizontal braking forces) into the substructure analysis system, i.e., the combined flood-vehicle effect. Combining the damage characteristics of scour depth, the horizontal and vertical forces of vehicle floods, flood velocity and depth, and the key parameters of the pier top bending moment, a mechanical model of the pier-cap-pile-soil system is established. By establishing a potential energy function for the system and applying the principle of potential energy stationary value, the pier top displacement and drift rate are calculated to assess the bearing capacity. This invention uses machine learning regression to predict pier top displacement values, taking into account factors such as scour depth, with excellent results and high accuracy. This method provides efficient quantitative characterization of the substructure's bearing capacity, providing systematic and reliable theoretical and technical support for practical bridge disaster prevention design and risk assessment.

[0172] See also Figure 5 The present invention provides a system for assessing the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads, comprising:

[0173] The first model construction module is used to construct a pier-cap-pile-soil system model of the substructure, and is used to apply vehicle load, flood load, additional bending moment at the pier top, bridge scour depth, and flood inundation depth to the pier-cap-pile-soil system model to obtain a mechanical model of the pier-cap-pile-soil system;

[0174] a first calculation module for calculating a total potential energy function of the pier-cap-pile-soil system, setting a horizontal displacement curve function of the pier-cap-pile-soil system, and setting boundary conditions of the pier-cap-pile-soil system, wherein the horizontal displacement curve function includes undetermined parameters;

[0175] The second calculation module is used to construct a linear algebraic equation of the undetermined parameters based on the principle of stationary value of potential energy, solve the undetermined parameters, and obtain the pier top displacement;

[0176] A third calculation module is used to calculate the pier top drift rate, which is used to assess the bearing capacity of the lower part of the bridge;

[0177] The second model building module is used to build a substructure bearing capacity assessment model, the input of which is the working condition parameters that affect the bearing capacity of the bridge substructure, and the output includes the pier top displacement and the pier top drift rate.

[0178] In this embodiment, the second calculation module is used to construct the linear algebraic equation of the undetermined parameters based on the potential energy stationary value principle, specifically for finding the first-order variation of the total potential energy function to be zero, and obtaining the linear algebraic equation .

[0179] In this embodiment, the second model construction module is specifically used to perform Latin hypercube sampling on the operating parameters affecting the lower bearing capacity of the bridge when training the lower structure bearing capacity assessment model, and the lower structure bearing capacity assessment model adopts the XGBoost machine learning regression model; it is used to establish a nonlinear mapping relationship between the input operating parameters affecting the lower bearing capacity of the bridge and the pier top displacement when constructing the lower structure bearing capacity assessment model.

[0180] In this embodiment, an evaluation module is also included, which is used to evaluate the bearing capacity of the lower part of the bridge according to the lower structure bearing capacity evaluation model.

[0181] The assessment system provided in this embodiment incorporates vehicle-flood coupling based on bridge scour damage. Furthermore, a specific multi-load processing module is designed based on all considered loads. This module establishes a total potential energy function for the structure under combined loads and solves the horizontal displacement curve function to determine pier top displacement. This allows this embodiment to more accurately simulate the actual stress conditions of scour-damaged bridges and more precisely determine the bridge's bearing capacity. Furthermore, this embodiment employs a machine learning-based driving method to establish a model of operating parameters and pier top displacements that affect the bridge's lower bearing capacity, enabling rapid assessment of the lower bearing capacity of scour-damaged bridges under the combined effects of multiple loads. This embodiment also incorporates a normalized metric, the pier top drift rate, to intuitively reflect the relative degree of deformation of the piers under flood scour damage.

[0182] See also Figure 6 The present invention also provides an electronic device, comprising: a memory; one or more processors; one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs include instructions for executing any one of the methods for assessing the bearing capacity of the lower part of a scour-damaged bridge under the action of multiple loads.

[0183] The present invention also provides a computer program product, including a computer program or instructions, which, when executed by a processor, implements the method for assessing the bearing capacity of the lower part of a scour-damaged bridge under multiple loads as described in any of the above embodiments.

[0184] The processor may be a central processing unit (CPU), or other general-purpose processors, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0185] The memory may include various types of storage units, such as system memory, read-only memory (ROM), and permanent storage devices. In addition, the memory may include any combination of computer-readable storage media, such as semiconductor memory chips, magnetic disks, and optical disks.

[0186] The memory stores executable codes, which, when processed by the processor, can enable the processor to execute part or all of the above-mentioned methods.

[0187] Those skilled in the art to which the present invention belongs can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0188] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above. For the sake of simplicity, they are not provided in detail. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for assessing the bearing capacity of the lower part of a scour-damaged bridge under multiple loads, characterized in that: include: Construct a pier-cap-pile-soil system model for the substructure; The vehicle load, flood load, additional bending moment on the pier top, bridge scour depth, and pier submergence depth are introduced as action conditions into the pier-cap-pile-soil system model to obtain a mechanical model of the pier-cap-pile-soil system. Calculating the total potential energy function of the pier-cap-pile-soil system, establishing a horizontal displacement curve function of the pier-cap-pile-soil system, and setting boundary conditions of the pier-cap-pile-soil system, wherein the established horizontal displacement curve function includes undetermined parameters; Based on the principle of stationary value of potential energy, a linear algebraic equation of the unknown parameters is constructed; the unknown parameters are solved to obtain the pier top displacement; Calculating the pier top drift rate, which is used to assess the bearing capacity of the lower part of the bridge; A substructure bearing capacity assessment model is constructed, wherein the input of the substructure bearing capacity assessment model is the working condition parameters that affect the bearing capacity of the substructure of the bridge, and the output includes the pier top displacement and the pier top drift rate.

2. The method for assessing the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads as claimed in claim 1, wherein: The vehicle load is the vertical concentrated force acting on the pier top and the horizontal braking force acting on the pier top. The flood load is the transverse component of the flood dynamic pressure and the longitudinal component of the flood dynamic pressure. The flood dynamic pressure is the flood dynamic pressure in the form of a uniformly distributed load. The transverse component of the flood dynamic pressure is expressed as: The longitudinal bridge component of the flood dynamic pressure is expressed as: ;in, It represents the time-averaged resistance per unit length of flood load in the transverse direction of the bridge. It represents the time-averaged resistance per unit length of flood load in the longitudinal direction of the bridge. represents the resistance coefficient per unit length, is the water density, Indicates the area per unit length of the bridge perpendicular to the water flow direction, It represents the average flow velocity of the cross section. It indicates the incident angle of flood water relative to the transverse direction of the bridge pier.

3. The method for assessing the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads as claimed in claim 1, wherein: The total potential energy function includes the bending strain energy of the pier-cap-pile-soil system , Strain energy of sliding bearing at top of pier , pile-soil spring strain energy , axial force work , the work done by the pier-cap-pile-soil system's own gravity , horizontal braking force and additional bending moment work at pier top , work done by dynamic water pressure .

4. The method for assessing the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads as claimed in claim 3, wherein: The axial force work includes the vertical concentrated force work acting on the pier top in the vehicle load, the axial force equivalent to the superstructure acting on the pier top, and the axial force equivalent to the gravity of the cap acting on the pile top; The horizontal braking force and the additional bending moment on the pier top do the work Expressed as: ;in, It represents the horizontal braking force acting on the pier top in the vehicle load. represents the displacement of the pier top, represents the additional bending moment at the pier top, Indicates the pier top angle; The hydrodynamic pressure does work Expressed as: ;in, The time-averaged resistance component of the flood load acting on the length of the bridge pier is expressed as the longitudinal component of the bridge. The time-averaged resistance component of the flood load acting on the pile length is expressed as the longitudinal component of the bridge. represents the horizontal displacement curve function value, Indicates the height of the initial scour line from the pile top, represents the equivalent single pile length, Indicates the height of the water level from the pier top. Indicates the total height of the pier-cap-pile-soil system, Indicates the bridge scour depth.

5. The method for assessing the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads as claimed in claim 1, wherein: The horizontal displacement curve function of the pier-cap-pile-soil system is established as follows: ;in, represents the horizontal displacement curve function value, as well as represents the undetermined parameters of the horizontal displacement curve function; Indicates the trial function number, a total of A test function, represents the axial coordinate of the pier-cap-pile-soil system, Indicates the total height of the pier-cap-pile-soil system.

6. The method for assessing the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads as claimed in claim 1, wherein: The constraint conditions of the pier-cap-pile-soil system are that the pile bottom is hinged, the pier top is free, and the pier top bears the horizontal braking force of the vehicle load and the additional bending moment of the pier top; the boundary conditions include force boundary conditions and displacement boundary conditions, and the force boundary conditions are: ;in, represents the bending stiffness of the pier, represents the second-order derivative of the pier top displacement, represents the additional bending moment at the pier top, represents the third-order derivative of the pier top displacement, Indicates the horizontal braking force of the vehicle load on the pier top, represents the sliding bearing stiffness of the pier top bearing, represents the displacement of the pier top; The displacement boundary condition is: ;in, represents the displacement of the pile bottom, represents the second-order derivative of pile bottom displacement.

7. The method for assessing the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads as claimed in claim 1, wherein: The linear algebraic equation for the undetermined parameters is constructed based on the principle of stationary potential energy. The linear algebraic equation is obtained by taking the first-order variation of the total potential energy function to zero, obtaining the partial differential equations of the undetermined parameters, and obtaining the linear algebraic equation ,in represents the stiffness matrix, represents the unknown parameter matrix, represents the equivalent load matrix.

8. The method for assessing the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads as claimed in claim 1, wherein: When training the substructure bearing capacity assessment model, Latin hypercube sampling is performed on the working condition parameters that affect the bearing capacity of the bridge substructure. The substructure bearing capacity assessment model adopts the XGBoost machine learning regression model. When constructing the substructure bearing capacity assessment model, a nonlinear mapping relationship between the input working condition parameters that affect the bearing capacity of the bridge substructure and the pier top displacement is established: ； in, represents a nonlinear function, Indicates the bridge scour depth, Indicates the depth of flooding, The axial force at the top of the pier, Indicates flood flow speed, Indicates the flood water incident angle, represents the additional bending moment at the pier top, Indicates the horizontal braking force of the vehicle load on the pier top.

9. The method for assessing the bearing capacity of the lower portion of a scour-damaged bridge under multiple loads as claimed in claim 1, wherein: The vehicle load is the vertical concentrated force acting on the pier top and the horizontal braking force acting on the pier top. The horizontal braking force acting on the pier top is calculated as 10% of the total gravity of the vehicle uniformly distributed load within the loading length range.

10. The system for assessing the bearing capacity of the lower part of a scour-damaged bridge under multiple loads is characterized by: include: The first model construction module is used to construct a pier-cap-pile-soil system model of the substructure, and is used to introduce vehicle load, flood load, additional bending moment at the pier top, bridge scour depth, and flood inundation depth as action conditions into the pier-cap-pile-soil system model to obtain a pier-cap-pile-soil system mechanical model; a first calculation module, configured to calculate a total potential energy function of the pier-cap-pile-soil system, establish a horizontal displacement curve function of the pier-cap-pile-soil system, and set boundary conditions of the pier-cap-pile-soil system, wherein the established horizontal displacement curve function includes undetermined parameters; A second calculation module is used to construct a linear algebraic equation of the undetermined parameters based on the principle of stationary value of potential energy; Used to solve the unknown parameters and obtain the pier top displacement; A third calculation module is used to calculate the pier top drift rate, which is used to assess the bearing capacity of the lower part of the bridge; The second model building module is used to build a substructure bearing capacity assessment model. The input of the substructure bearing capacity assessment model is the working condition parameters that affect the bearing capacity of the bridge substructure, and the output includes pier top displacement and pier top drift rate.

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