Water-sand composite abrasion-based mountain bridge pier durability evaluation method and system

Abstract

The application discloses a mountain bridge pier durability evaluation method and system based on water-sand composite abrasion, and belongs to the technical field of bridge structure safety evaluation. A composite abrasive model considering tangential cutting and normal impact is established, the composite abrasive model is discretely solved by a smoothed particle hydrodynamics solver, and an initial mountain bridge pier abrasion rate calculation model is constructed. Orthogonal test simulation is carried out based on Box-Behnken design method and central composite design method, curve estimation theory and multivariate nonlinear regression theory are combined, the influences of river depth, pier diameter, water-sand mixed particle flow velocity before impact, sand content, silt particle roundness coefficient and concrete compressive strength on the abrasion rate are considered, and a high-precision bridge pier water-sand abrasion rate calculation model is constructed. Based on the high-precision bridge pier water-sand abrasion rate calculation model and hydrological working condition data at the bridge site, the annual abrasion depth of the bridge pier is calculated, and whether the durability performance of the bridge pier can meet the service requirements is evaluated based on the concrete protective layer thickness and the annual abrasion depth of the bridge pier.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bridge structure safety, and more particularly relates to a mountain bridge pier durability evaluation method and system based on water-sand composite abrasion. BACKGROUND

[0002] At present, the simulation research on concrete abrasion has made certain progress, but the abrasive particle models used are mostly constructed for typical plastic or brittle materials such as metals and ceramics. The physical and mechanical properties of these materials are significantly different from those of concrete, and their abrasion mechanism is difficult to be directly applied to concrete. Concrete is a typical multi-phase composite quasi-brittle material composed of cement, sand aggregate, water and other multi-phase materials. Its internal structure is complex, and the mechanical properties show inhomogeneity and anisotropy. Under the action of tangential cutting and normal impact of sand and gravel in water flow, concrete will produce complex composite damage. This composite damage mechanism is essentially different from the abrasion mechanism of materials such as metals and ceramics. Therefore, the existing abrasive particle models cannot accurately simulate the damage evolution process of concrete under the action of water-sand abrasion.

[0003] At present, the calculation model for the water-sand abrasion of bridge piers is still in a blank state. The lack of a calculation model that can accurately describe the damage accumulation, strength degradation and durability decay of concrete under the action of water-sand abrasion results in the inability to scientifically and accurately evaluate the durability of bridge piers in actual service environment. At the same time, the evaluation method for the durability of bridge piers under the action of water-sand abrasion has not been established, and there is a lack of effective technical means in engineering practice to predict and evaluate the service life of bridge piers under long-term abrasion, making it difficult to take targeted protective measures in advance, which brings potential risks to the safe operation of mountain river-crossing bridges. SUMMARY

[0004] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a method and system for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion. First, a composite abrasive model (concrete abrasion model) considering the composite action of tangential cutting and normal impact is constructed, and a smooth particle element solver is used to discretize the composite abrasive model to obtain the abrasion rate of the pier boundary particles. Subsequently, through the Box-Behnken design method and the central composite design method, combined with multivariate nonlinear regression analysis, the influence of multiple factors such as river water depth, pier pile diameter, velocity of water-sand mixed particles before impact, sand content, roundness coefficient of sediment particles, and concrete compressive strength on the abrasion rate is systematically identified and quantified, and a high-precision abrasion rate prediction model is established. Finally, combined with the hydrological working condition data of the bridge site, the annual abrasion depth of the bridge pier is calculated, and based on the thickness of the concrete protective layer and the annual abrasion depth of the bridge pier, it is evaluated whether the durability of the bridge pier meets the service requirements. The method of the present invention covers the entire process from abrasion mechanism modeling to engineering durability evaluation, filling the technical gap in concrete water-sand abrasion modeling and bridge pier durability evaluation, and can provide a scientific basis for the design and protection of bridges in mountainous areas.

[0005] To achieve the above objectives, one aspect of the present invention provides a method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion, comprising the following steps:

[0006] S1. Calculate the abrasive rate of particles at the impacted bridge pier boundary based on the momentum theorem, establish a composite abrasive particle model that takes into account tangential cutting and normal impact, discretize the composite abrasive particle model using a smoothed particle element solver, and construct an initial calculation model for the abrasive rate of bridge piers in mountainous areas.

[0007] S2. Determine multiple factors affecting the water-sand erosion of bridge piers. Based on the Box-Behnken design method, perform a multi-factor three-level orthogonal test simulation on the initial calculation model for the erosion rate of mountainous bridge piers. Based on the curve estimation theory, construct a preliminary calculation model for the water-sand erosion rate of mountainous bridge piers based on the composite abrasive model. Verify whether the precise solution of the model meets the requirements. If so, use the preliminary calculation model for the water-sand erosion rate of mountainous bridge piers based on the composite abrasive model as the final calculation model for the water-sand erosion rate of bridge piers, and execute step S4. Otherwise, execute the next step.

[0008] S3. Identify the main control parameters that have the most significant impact on the abrasion rate. Based on the central composite design method, conduct a three-factor, five-level orthogonal test simulation on the initial calculation model for the abrasion rate of mountainous bridge piers. Based on the multivariate nonlinear regression theory, construct a final calculation model for the water-sand abrasion rate of mountainous bridge piers based on the composite abrasive model.

[0009] S4. Based on the final water-sand erosion rate calculation model for mountain bridge piers based on the composite abrasive model and the hydrological operating conditions data at the bridge site, the annual erosion depth of the bridge piers is calculated, and based on the thickness of the concrete cover and the annual erosion depth of the bridge piers, whether the durability of the bridge piers can meet the service requirements is evaluated.

[0010] Furthermore, step S1 includes:

[0011] S11: Considering the tangential cutting and normal impact effects, the tangential and normal rebound velocities of water-sand mixture particles after impacting the bridge pier are calculated based on the momentum theorem;

[0012] S12: Calculate the abrasive rate of the particles at the boundary of the impacted bridge pier based on the tangential and normal rebound velocities of the water-sand mixture particles after impacting the bridge pier, and obtain a composite abrasive model that considers both tangential cutting and normal impact.

[0013] S13: Discretize the composite abrasive particle model considering tangential cutting and normal impact in a smooth particle element solver, perform weighted summation using kernel function values, and calculate the total abrasion rate of the pier boundary particles within the solution time.

[0014] Furthermore, in step S12, the composite abrasive model considering the tangential cutting and normal impact is expressed by formula (7):

[0015] (7)

[0016] in, is the abrasion rate of particles at the impacted pier boundary, 、 are the abrasive mass caused by the tangential cutting and normal impact of water-sand mixed particles on the pier boundary particles, is the concrete abrasion area, is the duration of abrasion;

[0017] The abrasive mass caused by the tangential cutting and normal impact of the water-sand mixture particles on the pier boundary particles is calculated by equations (8) and (9):

[0018] (8)

[0019] (9)

[0020] in, is the mass of sediment particles during the abrasion process, 、 are the hardness of sediment particles and the hardness of concrete, and are the tangential and normal rebound velocities of water-sand mixture particles, respectively; and are the tangential and normal velocities of the water-sand mixture particles before impact, respectively; is the compressive strength of concrete, 、 are cutting coefficient and deformation coefficient respectively; is the roundness coefficient of sediment particles; Calculated by formula (10):

[0021] (10)

[0022] in, is the critical wear coefficient.

[0023] Furthermore, the initial calculation model for the abrasion rate of bridge piers in mountainous areas is expressed by formula (12):

[0024] (12)

[0025] in, The boundary particles of the pier Total abrasion rate; For each pier boundary particle Each water-sand mixture particle within the kernel function radius The rate of abrasion caused; is the kernel function value of the pier boundary particles; Represents water-sand mixed particles volume;

[0026] Each pier boundary particle Each water-sand mixture particle within the kernel function radius The abrasion rate caused Calculated by formula (13):

[0027] (13)

[0028] in, 、 Water-sand mixed particles The particles at the bridge pier boundary The abrasive quality of tangential cutting and normal impact; The boundary particles of the pier Water-sand mixed particles The area abraded; is the duration of abrasion.

[0029] Furthermore, step S2 includes:

[0030] S21: Determine the factors affecting water-sand erosion of bridge piers through literature research, engineering experience, or field investigations; the factors affecting water-sand erosion of bridge piers include river depth, pier pile diameter, velocity of water-sand mixture particles before impact, sand content, sediment particle roundness coefficient, and concrete compressive strength;

[0031] S22: Use the Box-Behnken design method to set three levels of low, medium, and high for each influencing factor. Use statistical software to automatically generate a Box-Behnken orthogonal simulation test plan, and specify the specific values ​​of each influencing factor under each experimental condition in the test plan;

[0032] S23: Conducting tests or numerical simulations for each test scheme, and calculating and obtaining abrasion rate data under different combinations of influencing factors using the initial mountain bridge pier abrasion rate calculation model;

[0033] S24: Using the multivariate nonlinear regression method, the erosion rate data under different combinations of influencing factors were fitted to establish a preliminary mathematical model between the erosion rate and the influencing factors, i.e., a preliminary water-sand erosion rate calculation model for mountain bridge piers based on a composite abrasive particle model;

[0034] The preliminary calculation model of the water-sand erosion rate of mountain bridge piers based on the composite abrasive model in step S24 is expressed by formula (14):

[0035] (14)

[0036] in, is the abrasion rate of particles at the impacted pier boundary; For the depth of the river, is the diameter of the pier pile, is the velocity of water-sand mixture particles before impact, is the sand content, is the roundness coefficient of sediment particles, is the compressive strength of concrete; are the coefficients of each item, ; is a constant term, which is the model benchmark value and represents the basic abrasion rate when all influencing factors are zero; are the linear coefficients, representing the river depth , Pier pile diameter , velocity of water-sand mixture before particle collision , sand content , sediment particle roundness coefficient , concrete compressive strength The degree of linear effect on the abrasion rate; are interaction coefficients, representing the river depth and the diameter of the pier pile , velocity of water-sand mixture before particle collision , sand content , sediment particle roundness coefficient , concrete compressive strength , pier pile diameter Flow velocity before collision with water-sand mixture particles , sediment particle roundness coefficient , concrete compressive strength , velocity of water-sand mixture before particle collision and sand content , sediment particle roundness coefficient , concrete compressive strength , sand content and sediment particle roundness coefficient , concrete compressive strength , and the sediment particle roundness coefficient and concrete compressive strength The effect of interaction between them on the abrasion rate; is the quadratic coefficient, which indicates the nonlinear (quadratic) effect of each influencing factor and reflects the nonlinear change trend of the influencing factors on the abrasion rate. , Pier pile diameter , velocity of water-sand mixture before particle collision , sand content , sediment particle roundness coefficient , concrete compressive strength Nonlinear variation trend of abrasion rate.

[0037] Furthermore, step S3 includes:

[0038] Performing a sensitivity analysis or variance analysis on the preliminary water-sand erosion rate calculation model for mountain bridge piers based on the composite abrasive particle model, identifying at least three factors that most significantly affect the erosion rate as primary control parameters; the primary control parameters include the velocity of the water-sand mixture before impact, the diameter of the pier pile, and the compressive strength of the concrete;

[0039] The central composite design method is used to set 5 levels for each main control parameter, automatically generate the test plan, and clarify the specific values ​​of each main control parameter under each test condition;

[0040] Conducting tests or numerical simulations on each test plan using the initial mountain bridge pier abrasion rate calculation model to obtain abrasion rate data under different combinations of main control parameters;

[0041] The multivariate nonlinear regression method was used to fit the abrasion rate data under different combinations of main control parameters, and the final mathematical model between the abrasion rate and the main control parameters was established, that is, the final water-sand abrasion rate calculation model for mountainous bridge piers based on the composite abrasive model.

[0042] Furthermore, the final calculation model of water-sand erosion rate of mountain bridge piers based on the composite abrasive model is expressed by formula (15):

[0043] (15)

[0044] in, is the abrasion rate of particles at the impacted pier boundary; is the velocity of water-sand mixture particles before impact; is the compressive strength of concrete; is the diameter of the pier pile; is a constant term, which represents the basic abrasion rate when all main control parameters are zero; are the linear coefficients, representing the velocity of the water-sand mixture before the collision of particles , concrete compressive strength , Pier pile diameter The degree of linear effect on the abrasion rate; are the interaction coefficients, representing the velocity of water-sand mixture particles before impact. Compressive strength of concrete , velocity of water-sand mixture before particle collision Pier diameter , concrete compressive strength Pier diameter The effect of interaction between them on the abrasion rate; are quadratic coefficients, representing the velocity of water-sand mixture before collision , concrete compressive strength , Pier pile diameter Quadratic nonlinear effect on the wear rate.

[0045] Furthermore, the hydrological operating condition data at the bridge site in step S4 include the river depth under the hydrological operating condition, the diameter of the bridge pier pile, the velocity of the water-sand mixture before collision, the sand content, the roundness coefficient of the sediment particles, and the compressive strength of the concrete;

[0046] The annual erosion depth of the bridge pier in step S4 is calculated by formula (16):

[0047] (16)

[0048] in, is the annual erosion depth, Indicates the hydrological conditions, Indicates the The abrasion rate under different hydrological conditions, Indicates the The accumulated erosion time of various hydrological conditions is: is the density of concrete.

[0049] Furthermore, the durability performance evaluation in step S4 is calculated according to formula (17):

[0050] (17)

[0051] in, is the concrete cover erosion time, Indicates the thickness of the concrete cover; Indicates the design service time;

[0052] If the concrete cover wear time is greater than the design service time, it means that the durability of the pier can meet the design requirements within the design service time;

[0053] If the abrasion time of the concrete cover is less than or equal to the design service time, it means that the durability of the pier does not meet the design requirements within the design service time and additional protective measures need to be taken.

[0054] A second aspect of the present invention provides a system for evaluating the durability of bridge piers in mountainous areas based on water-sand combined erosion, which is used to implement the aforementioned method for evaluating the durability of bridge piers in mountainous areas based on water-sand combined erosion, comprising:

[0055] The first main module provides a user input interface for inputting pier structural parameters, material parameters, and hydrological operating parameters. Pier structural parameters include pier pile diameter and shape; material parameters include concrete compressive strength, density, and protective layer thickness; and hydrological operating parameters include river depth, velocity before water-sand mixture impact, sand content, sediment particle size, and sediment particle roundness coefficient.

[0056] The second main module is used to calculate the abrasion rate of particles at the impacted bridge pier boundary based on the momentum theorem, establish a composite abrasive particle model that takes into account tangential cutting and normal impact, and discretize the composite abrasive particle model using a smoothed particle element solver to construct an initial calculation model for the abrasion rate of mountainous bridge piers.

[0057] The third main module determines multiple influence factors of the water-sand erosion of the bridge pier column, performs a 3-level orthogonal test simulation on the initial mountain bridge pier erosion rate calculation model based on a Box-Behnken design method, constructs a preliminary mountain bridge pier water-sand erosion rate calculation model based on a composite abrasive particle model based on a curve estimation theory, and verifies whether the model accurate solution meets the requirements, if yes, the preliminary mountain bridge pier water-sand erosion rate calculation model based on the composite abrasive particle model is taken as a final bridge pier water-sand erosion rate calculation model and the fifth main module is executed, otherwise, the next step is executed;

[0058] The fourth main module is used for identifying the most significant main control parameter affecting the erosion rate, performing a 3-factor 5-level orthogonal test simulation on the initial mountain bridge pier erosion rate calculation model based on a central composite design method, and constructing a final mountain bridge pier water-sand erosion rate calculation model based on a composite abrasive particle model based on a multivariate nonlinear regression theory;

[0059] The fifth main module is used for calculating the annual erosion depth of the bridge pier based on the final mountain bridge pier water-sand erosion rate calculation model based on the composite abrasive particle model and the hydrological working condition data at the bridge site.

[0060] The sixth main module is used for evaluating whether the durability performance of the bridge pier meets the service requirements according to the concrete protective layer thickness and the annual erosion depth of the bridge pier concrete.

[0061] Overall, compared with the prior art, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0062] (1) The durability evaluation method and system of mountain bridge piers based on water-sand composite abrasion of the present invention aims at the problem that in the prior art, abrasion simulation research mostly adopts abrasive models constructed for single homogeneous materials such as metals and ceramics, which cannot accurately describe the damage evolution process of multi-phase composite quasi-brittle materials such as concrete under water-sand abrasion. For the first time, a composite abrasive model considering the composite action of tangential cutting and normal impact is proposed, and the abrasion action of mountain highway bridge foundation is numerically simulated by using smooth particle element solver (SPH), and the abrasion rate data of bridge piers under water-sand abrasion are obtained, thereby improving the calculation efficiency and stability. The present invention takes into account the river depth, bridge pier diameter, flow rate, sand content, particle roundness, concrete strength, etc. Multiple influencing factors were taken into consideration, and the abrasion effect of mountain highway bridge foundations was simulated by the Box-Behnken design method and the central composite design method. According to the simulation test results, a water-sand abrasion rate calculation model for mountain piers was constructed by curve estimation theory and multivariate nonlinear regression theory, which can more realistically simulate the abrasion behavior of concrete under complex water flow conditions and significantly improve the simulation accuracy. Compared with the simplified model in the prior art that only considers a single or a small number of factors, the present invention can better reflect the complex working conditions in actual engineering, improve the engineering applicability and prediction accuracy of the model, and thus can more accurately evaluate the service durability of mountain bridge foundations under water-sand abrasion, thereby providing a reference for the design and defense of mountain bridge piers.

[0063] (2) The present invention's method and system for evaluating the durability of mountain bridge piers based on water-sand composite abrasion not only proposes a method for calculating the abrasion rate, but also further combines the hydrological data at the bridge site to quantitatively calculate the annual abrasion depth of the bridge piers, and evaluates the durability of the bridge piers based on the thickness of the concrete cover and the annual abrasion depth of the bridge piers. This complete technical chain of "abrasion mechanism - abrasion prediction - durability evaluation" is still a blank in the existing technology and has important engineering application value. The present invention can accurately predict the abrasion depth and durability degradation trend of bridge piers during their service life, thus providing a scientific basis for the optimization design of bridge pier structures, material selection, and the formulation of protective measures, effectively extending the service life of bridges and reducing maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 This is a flow chart of a method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion according to an embodiment of the present invention;

[0065] Figure 2 This is a schematic diagram of a flow chart for calculating the total abrasion rate of pier boundary particles in a method for evaluating the durability of mountain piers based on water-sand composite abrasion according to an embodiment of the present invention. In the figure, the fluid particles are water-sand mixed particles; the structural boundary particles are pier boundary particles.

[0066] Figure 3This is an overall logic diagram of a method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion according to an embodiment of the present invention;

[0067] Figure 4 This is a schematic structural diagram of a system for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion according to an embodiment of the present invention;

[0068] Figure 5 The figure is a schematic structural diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0069] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0070] like Figure 1-Figure 3 As shown, one aspect of the present invention provides a method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion, comprising the following steps:

[0071] S1. Calculate the abrasive rate of particles at the impacted bridge pier boundary based on the momentum theorem, establish a composite abrasive particle model that takes into account tangential cutting and normal impact, discretize the composite abrasive particle model using a smoothed particle element solver, and construct an initial calculation model for the abrasive rate of bridge piers in mountainous areas.

[0072] S2. Determine multiple factors affecting the water-sand erosion of bridge piers. Based on the Box-Behnken design method, perform a multi-factor three-level orthogonal test simulation on the initial calculation model for the erosion rate of mountainous bridge piers. Based on the curve estimation theory, construct a preliminary calculation model for the water-sand erosion rate of mountainous bridge piers based on the composite abrasive model. Verify whether the precise solution of the model meets the requirements. If so, use the preliminary calculation model for the water-sand erosion rate of mountainous bridge piers based on the composite abrasive model as the final calculation model for the water-sand erosion rate of bridge piers, and execute step S4. Otherwise, execute the next step.

[0073] S3. Identify the main control parameters that have the most significant impact on the abrasion rate. Based on the central composite design method, conduct a three-factor, five-level orthogonal test simulation on the initial calculation model for the abrasion rate of mountainous bridge piers. Based on the multivariate nonlinear regression theory, construct a final calculation model for the water-sand abrasion rate of mountainous bridge piers based on the composite abrasive model.

[0074] S4. Based on the final water-sand erosion rate calculation model for mountain bridge piers based on the composite abrasive model and the hydrological operating conditions data at the bridge site, the annual erosion depth of the bridge piers is calculated, and based on the thickness of the concrete cover and the annual erosion depth of the bridge piers, whether the durability of the bridge piers can meet the service requirements is evaluated.

[0075] Furthermore, step S1 includes:

[0076] S11: Considering the tangential cutting and normal impact effects, the tangential and normal rebound velocities of water-sand mixture particles after impacting the bridge pier are calculated based on the momentum theorem;

[0077] S12: Calculate the abrasive rate of the particles at the boundary of the impacted bridge pier based on the tangential and normal rebound velocities of the water-sand mixture particles after impacting the bridge pier, and obtain a composite abrasive model that considers both tangential cutting and normal impact.

[0078] S13: discretizing the composite abrasive particle model considering tangential cutting and normal impact in a smooth particle element solver, performing weighted summation using kernel function values, and calculating the total abrasion rate of the pier boundary particles within the solution time;

[0079] Furthermore, step S11 includes:

[0080] Collect physical parameters of the pier surface, including the pier friction coefficient;

[0081] Calculate the velocity components of the water-sand mixture particles in the tangential and normal directions before impact based on the flow velocity and impact angle before impact;

[0082] The tangential and normal rebound coefficients of the water-sand mixture particles are calculated based on the impact angle of the water-sand mixture particles and the friction coefficient of the bridge pier;

[0083] Calculating the tangential and normal rebound velocities of the water-sand mixture particles after they impact the bridge pier based on the tangential and normal velocity components of the water-sand mixture particles before impact and the tangential and normal rebound coefficients of the water-sand mixture particles;

[0084] The tangential and normal rebound velocities of the water-sand mixture particles after impacting the bridge pier are calculated by equations (1) and (2), respectively:

[0085] (1)

[0086] (2)

[0087] in, and are the tangential and normal rebound velocities of water-sand mixture particles, respectively; and are the tangential and normal velocities of the water-sand mixture particles before impact, respectively; and is the tangential and normal coefficient of restitution of the water-sand mixed particle; the tangential and normal velocity of the water-sand mixed particle before impact and calculated by formula (3) and formula (4):

[0088] (3)

[0089] (4)

[0090] wherein, is the impact angle, is the flow velocity of the water-sand mixed particle before impact;

[0091] the tangential and normal coefficient of restitution of the water-sand mixed particle and calculated by formula (5) and formula (6):

[0092] (5)

[0093] (6)

[0094] wherein, is the impact angle, is a constant, is the friction coefficient of the pier;

[0095] Further, the step S12 comprises:

[0096] According to the tangential and normal rebound velocity of the water-sand mixed particle after impacting the pier, the tangential cutting and normal impact abrasion mass of the single water-sand mixed particle to the boundary particle of the pier is calculated;

[0097] According to the tangential cutting and normal impact abrasion mass of the single water-sand mixed particle to the boundary particle of the pier, the abrasion area of the pier concrete and the abrasion duration, the abrasion rate of the boundary particle of the pier impacted is calculated, and a composite abrasive particle model considering the tangential cutting and normal impact is constructed.

[0098] Further, in the step S12, the composite abrasive particle model considering the tangential cutting and normal impact is represented by formula (7):

[0099] (7)

[0100] wherein, is the abrasion rate of the boundary particle of the pier impacted, , are the tangential cutting and normal impact abrasion mass of the water-sand mixed particle to the boundary particle of the pier respectively, is the concrete abrasion area, is the abrasion duration; the abrasion rate of the impacted pier boundary particles is calculated by formula (7);

[0101] The abrasive mass caused by the tangential cutting and normal impact of the water-sand mixture particles on the pier boundary particles is calculated by equations (8) and (9):

[0102] (8)

[0103] (9)

[0104] in, is the mass of sediment particles during the abrasion process, 、 are the hardness of sediment particles and the hardness of concrete, is the compressive strength of concrete, 、 are cutting coefficient and deformation coefficient respectively; is the roundness coefficient of sediment particles; Calculated by formula (10):

[0105] (10)

[0106] in, is the critical wear coefficient;

[0107] Sediment particle roundness coefficient Calculated by formula (11):

[0108] (11)

[0109] in, is the circumference of the vertical projection of the sand grain, is the circumference of the largest inscribed circle in the vertical projection of the sand grain;

[0110] Furthermore, in step S13, the composite abrasive particle model considering tangential cutting and normal impact is discretized in a smooth particle element solver, and a weighted sum is performed using kernel function values ​​to calculate the total abrasion rate of the pier boundary particles within the solution time; including:

[0111] Define the distribution and kernel function of the particles at the pier boundary;

[0112] The continuous composite abrasive particle model considering tangential cutting and normal impact is discretized by a smoothed particle element solver (SPH) and converted into a motion equation of a water-sand mixed particle system;

[0113] In each time step, the position, velocity, pressure and other information of the water-sand mixture particles are updated to simulate their motion state;

[0114] Check whether the water-sand mixture particles collide with the pier boundary particles; if no collision occurs, no processing is performed; if collision occurs, proceed to the next processing step;

[0115] When the water-sand mixture particles collide with the pier boundary particles, the rebound velocity and kinetic energy of each water-sand mixture particle are calculated. The abrasive rate caused by each water-sand mixture particle on the pier boundary particles is calculated using a composite abrasive particle model that considers tangential cutting and normal impact.

[0116] For each pier boundary particle, all water-sand mixture particles that collided and rebounded within the support radius of its kernel function were traversed, and the velocity, kinetic energy, and collision angle information of all water-sand mixture particles that collided and rebounded were extracted. Combined with the composite abrasive model considering tangential cutting and normal impact, the kernel function was used for weighted summation to obtain the total abrasion rate caused by all water-sand mixture particles on the pier boundary particles.

[0117] The total abrasion rate of the particles at the pier boundary is calculated by formula (12):

[0118] (12)

[0119] in, The boundary particles of the pier Total abrasion rate; For each pier boundary particle Each water-sand mixture particle within the kernel function radius The rate of abrasion caused; is the kernel function value of the pier boundary particles; Represents water-sand mixed particles volume;

[0120] Each pier boundary particle Each water-sand mixture particle within the kernel function radius The abrasion rate caused Calculated by formula (13):

[0121] (13)

[0122] in, 、 Water-sand mixed particles The particles at the bridge pier boundary The abrasive quality of tangential cutting and normal impact; The boundary particles of the pier Water-sand mixed particles The eroded area; The erosion duration;

[0123] The initial mountain bridge pier erosion rate calculation model is represented by formula (12).

[0124] Further, the Box-Behnken Design (BBD) is a commonly used response surface design method (RSM) for constructing a mathematical model between factors and responses, and is particularly suitable for multi-factor and multi-level experimental design. Step S2 comprises:

[0125] S21: determining the factors affecting the water-sand erosion of the bridge pier column through literature research, engineering experience or field investigation; the factors affecting the water-sand erosion of the bridge pier column include river depth, bridge pier column diameter, flow velocity before water-sand mixed particle impact, sand content, silt particle roundness coefficient, and concrete compressive strength;

[0126] S22: setting three levels of low, medium and high for each factor using the Box-Behnken Design method, and using statistical software (such as Design-Expert, Minitab, SPSS, R language, etc.) to automatically generate a Box-Behnken orthogonal simulation test scheme, and specifying the specific values of each factor under each test condition in the test scheme;

[0127] S23: testing or numerically simulating each test scheme, and calculating and obtaining the erosion rate data under different factor combinations through the initial mountain bridge pier erosion rate calculation model;

[0128] S24: fitting the erosion rate data under different factor combinations through a multivariate nonlinear regression method, and establishing a preliminary mathematical model between the erosion rate and the factors, i.e., a preliminary mountain bridge pier water-sand erosion rate calculation model based on the composite abrasive particle model;

[0129] Further, the water-sand erosion of the bridge pier column is related to multiple factors, and in the specific embodiments of the present application, the factors affecting the water-sand erosion of the bridge pier column in step S21 include river depth, bridge pier column diameter, flow velocity before water-sand mixed particle impact, sand content, silt particle roundness coefficient, and concrete compressive strength;

[0130] The preliminary mountain bridge pier water-sand erosion rate calculation model based on the composite abrasive particle model in step S24 is represented by formula (14):

[0131] (14)

[0132] in, is the abrasion rate of particles at the impacted pier boundary; For the depth of the river, is the diameter of the pier pile, is the velocity of water-sand mixture particles before impact, is the sand content, is the roundness coefficient of sediment particles, is the compressive strength of concrete; are the coefficients of each item, ; is a constant term, which is the model benchmark value and represents the basic abrasion rate when all influencing factors are zero; are the linear coefficients, representing the river depth , Pier pile diameter , velocity of water-sand mixture before particle collision , sand content , sediment particle roundness coefficient , concrete compressive strength The degree of linear effect on the abrasion rate; are interaction coefficients, representing the river depth and the diameter of the pier pile , velocity of water-sand mixture before particle collision , sand content , sediment particle roundness coefficient , concrete compressive strength , pier pile diameter Flow velocity before collision with water-sand mixture particles , sediment particle roundness coefficient , concrete compressive strength , velocity of water-sand mixture before particle collision and sand content , sediment particle roundness coefficient , concrete compressive strength , sand content and sediment particle roundness coefficient , concrete compressive strength , and the sediment particle roundness coefficient and concrete compressive strength The effect of interaction between them on the abrasion rate; is the quadratic coefficient, which indicates the nonlinear (quadratic) effect of each influencing factor and reflects the nonlinear change trend of the influencing factors on the abrasion rate. , Pier pile diameter , velocity of water-sand mixture before particle collision , sand content , sediment particle roundness coefficient , concrete compressive strength Nonlinear variation trend of abrasion rate.

[0133] In a specific embodiment of the present invention, step S22 is based on the Box-Behnken design method, and a 6-factor 3-level orthogonal experimental design is performed. The factors and levels of the experiment are listed in Table 1; the orthogonal simulation test scheme is listed in Table 2;

[0134] Table 1: 6-factor 3-level orthogonal experimental design

[0135]

[0136] Table 2: Orthogonal simulation test plan

[0137]

[0138] The water-sand erosion rate of bridge piers calculated according to the preliminary water-sand erosion rate calculation model for mountain bridge piers based on the composite abrasive model is as follows:

[0139] .

[0140] Furthermore, the central composite design is a multi-level experimental design method that constructs a quadratic polynomial regression model by reasonably selecting experimental points to analyze the impact of factors on the response variable and their interactions. Step S3 includes:

[0141] A sensitivity analysis or variance analysis is performed on the preliminary water-sand erosion rate calculation model for mountain bridge piers based on the composite abrasive particle model to identify at least three factors that most significantly affect the erosion rate as primary control parameters. In a specific embodiment of the present invention, the primary control parameters for the erosion rate include the velocity of the water-sand mixture before impact, the diameter of the bridge pier pile, and the compressive strength of the concrete.

[0142] A central composite design (CCD) method was used to set five levels (-α, -1, 0, +1, +α) for each control parameter, where α is the axial point to improve the model fitting accuracy. The test plan was automatically generated to clarify the specific values ​​of each control parameter under each test condition.

[0143] Conducting tests or numerical simulations on each test plan using the initial mountain bridge pier abrasion rate calculation model to obtain abrasion rate data under different combinations of main control parameters;

[0144] Using multiple nonlinear regression methods (such as response surface methodology, stepwise regression, and neural network regression), we fitted the abrasion rate data under different combinations of the main control parameters and established a final mathematical model between the abrasion rate and the main control parameters. This was the final water-sand abrasion rate calculation model for mountain bridge piers based on the composite abrasive particle model.

[0145] The final calculation model of water-sand erosion rate of mountain bridge piers based on the composite abrasive model is expressed by formula (15):

[0146] (15)

[0147] in, is the abrasion rate of particles at the impacted pier boundary; is the velocity of water-sand mixture particles before impact; is the compressive strength of concrete; is the diameter of the pier pile; is a constant term, which represents the basic abrasion rate when all main control parameters are zero; are the linear coefficients, representing the velocity of the water-sand mixture before the collision of particles , concrete compressive strength , Pier pile diameter The degree of linear effect on the abrasion rate; are the interaction coefficients, representing the velocity of water-sand mixture particles before impact. Compressive strength of concrete , velocity of water-sand mixture before particle collision Pier diameter , concrete compressive strength Pier diameter The effect of interaction between them on the abrasion rate; are quadratic coefficients, representing the velocity of water-sand mixture before particle collision , concrete compressive strength , Pier pile diameter Quadratic nonlinear effect on the wear rate.

[0148] In a specific embodiment of the present invention, the final water-sand abrasion rate of the mountain bridge pier calculated according to formula (15) is:

[0149] .

[0150] Furthermore, the hydrological operating condition data at the bridge site in step S4 include the river depth under the hydrological operating condition, the diameter of the bridge pier pile, the velocity of the water-sand mixture before collision, the sand content, the roundness coefficient of the sediment particles, and the compressive strength of the concrete;

[0151] The annual erosion depth of the pier in step S4 is calculated by formula (16):

[0152] (16)

[0153] wherein, is the annual erosion depth, represents a hydrological working condition, represents the erosion rate under the th hydrological working condition, represents the cumulative erosion time under the th hydrological working condition, is the density of concrete;

[0154] The durability evaluation is calculated according to formula (17):

[0155] (17)

[0156] wherein, is the erosion time of the concrete protective layer, represents the thickness of the concrete protective layer, represents the design service time; if the erosion time of the concrete protective layer is greater than the design service time, it indicates that the durability of the pier can meet the design requirements within the design service time;

[0157] If the erosion time of the concrete protective layer is less than or equal to the design service time, it means that the durability of the pier does not meet the design requirements within the design service time, and additional protective measures need to be taken.

[0158] Step S4 comprises:

[0159] determining the parameters of the th hydrological working condition, including the river water depth under the th hydrological working condition, the pier pier diameter, the flow velocity before water-sand mixed particle impact, the sand content, the silt particle roundness coefficient, and the concrete compressive strength;

[0160] substituting the parameters of the th hydrological working condition into the final mountainous bridge pier water-sand erosion rate calculation model formula (15) based on the composite abrasive particle model to calculate the erosion rate under the th hydrological working condition;

[0161] calculating the annual erosion depth of the pier concrete according to the erosion rate under the th hydrological working condition, the cumulative erosion time under the th hydrological working condition, and the density of concrete;

[0162] The durability of the bridge pier is evaluated according to the concrete protective layer thickness and the annual erosion depth of the bridge pier concrete.

[0163] As shown in Figure 4 The second aspect of the present application provides a mountain bridge pier durability evaluation system based on water-sand composite erosion, comprising:

[0164] The first main module provides a user input interface for inputting bridge pier structure parameters, material parameters and hydrological working condition parameters; the bridge pier structure parameters include bridge pier pier diameter and shape; the material parameters include concrete compressive strength, density and protective layer thickness; the hydrological working condition parameters include river water depth, pre-impact water-sand mixed particle flow velocity, sand content, sand particle size and sand particle roundness coefficient;

[0165] The second main module is used for calculating the erosion rate of the impacted bridge pier boundary particles based on the momentum theorem, establishing a composite abrasive particle model considering tangential cutting and normal impact action, discretely solving the composite abrasive particle model through a smooth particle element solver, and constructing an initial mountain bridge pier erosion rate calculation model;

[0166] The third main module determines multiple influence factors of the water-sand erosion of the bridge pier, performs a 3-level orthogonal test simulation on the initial mountain bridge pier erosion rate calculation model based on the Box-Behnken design method, constructs a preliminary mountain bridge pier water-sand erosion rate calculation model based on the composite abrasive particle model based on the curve estimation theory, and verifies whether the model accurate solution meets the requirements; if yes, the preliminary mountain bridge pier water-sand erosion rate calculation model based on the composite abrasive particle model is taken as the final bridge pier water-sand erosion rate calculation model and the fifth main module is executed; otherwise, the next step is performed.

[0167] The fourth main module is used for identifying the main control parameters that most significantly affect the erosion rate, performing a 3-factor 5-level orthogonal test simulation on the initial mountain bridge pier erosion rate calculation model based on the central composite design method, and constructing a final mountain bridge pier water-sand erosion rate calculation model based on the composite abrasive particle model based on the multivariate nonlinear regression theory.

[0168] The fifth main module is used for calculating the annual erosion depth of the bridge pier based on the final mountain bridge pier water-sand erosion rate calculation model based on the composite abrasive particle model and the hydrological working condition data at the bridge site.

[0169] The sixth main module is used for evaluating whether the durability of the bridge pier meets the service requirements according to the concrete protective layer thickness and the annual erosion depth of the bridge pier concrete.

[0170] The initial mountain bridge pier erosion rate calculation model is represented by formula (12):

[0171] (12)

[0172] in, The boundary particles of the pier Total abrasion rate; For each pier boundary particle Each water-sand mixture particle within the kernel function radius The rate of abrasion caused; is the kernel function value of the pier boundary particles;

[0173] The final calculation model of water-sand erosion rate of mountain bridge piers based on the composite abrasive model is expressed by formula (15):

[0174] (15)

[0175] in, is the abrasion rate of particles at the impacted pier boundary; is the velocity of water-sand mixture particles before impact; is the compressive strength of concrete; is the diameter of the pier pile; is a constant term, which represents the basic abrasion rate when all main control parameters are zero; are the linear coefficients, representing the velocity of the water-sand mixture before the collision of particles , concrete compressive strength , Pier pile diameter The degree of linear effect on the abrasion rate; are the interaction coefficients, representing the velocity of water-sand mixture particles before impact. Compressive strength of concrete , velocity of water-sand mixture before particle collision Pier diameter , concrete compressive strength Pier diameter The effect of interaction between them on the abrasion rate; are quadratic coefficients, representing the velocity of water-sand mixture before particle collision , concrete compressive strength , Pier pile diameter Quadratic nonlinear effect on the wear rate.

[0176] The annual abrasion depth of the bridge pier is calculated by formula (16):

[0177] (16)

[0178] in, is the annual erosion depth, Indicates the hydrological conditions, Indicates the The abrasion rate under different hydrological conditions, Indicates the The accumulated erosion time of various hydrological conditions is: is the density of concrete;

[0179] The durability evaluation is calculated according to formula (17):

[0180] (17)

[0181] in, is the concrete cover erosion time, Indicates the thickness of the concrete cover; Indicates the design service time;

[0182] If the concrete cover wear time is greater than the design service time, it means that the durability of the pier can meet the design requirements within the design service time;

[0183] If the abrasion time of the concrete cover is less than or equal to the design service time, it means that the durability of the pier does not meet the design requirements within the design service time and additional protective measures need to be taken.

[0184] It should be noted that the durability assessment system for mountain bridge piers based on water-sand combined abrasion provided in this embodiment can be a computer program (including program code) running in a computer device. For example, the durability assessment system for mountain bridge piers based on water-sand combined abrasion is an application software; the durability assessment system for mountain bridge piers based on water-sand combined abrasion can be used to execute the corresponding steps in the above-mentioned method provided in the embodiment of this application.

[0185] In some feasible implementations, the durability assessment system for mountain bridge piers based on water-sand composite abrasion provided by this embodiment can be implemented by a combination of software and hardware. As an example, the durability assessment system for mountain bridge piers based on water-sand composite abrasion provided by this embodiment can be a processor in the form of a hardware decoding processor, which is programmed to execute the durability assessment method for mountain bridge piers based on water-sand composite abrasion provided by this embodiment. For example, the processor in the form of a hardware decoding processor can adopt one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), or other electronic components.

[0186] In some feasible implementations, the mountain bridge pier durability assessment system based on water-sand composite abrasion provided in this embodiment can be implemented in a software manner, which can be software in the form of programs and plug-ins, and include a series of modules to implement the mountain bridge pier durability assessment method based on water-sand composite abrasion provided in the embodiment of the present invention.

[0187] A third aspect of the present invention further provides an electronic device, Figure 5 Schematic diagram of the structure of the electronic device of this embodiment. Figure 5 As shown, the electronic device 1000 in this embodiment may include: a processor 1001, a network interface 1004 and a memory 1005. In addition, the above-mentioned electronic device 1000 may also include: a user interface 1003, and at least one communication bus 1002. The communication bus 1002 is used to realize the connection and communication between these components. The user interface 1003 may include a display screen (Display), a keyboard (Keyboard), and the user interface 1003 may optionally include a standard wired interface and a wireless interface. The network interface 1004 may optionally include a standard wired interface and a wireless interface (such as a WI-FI interface). The memory 1005 may be a high-speed RAM memory, or a non-volatile memory (non-volatile memory), such as at least one disk memory. The memory 1005 may optionally also be at least one storage device located away from the aforementioned processor 1001. As Figure 5As shown, the memory 1005 as a computer-readable storage medium may include an operating system, a network communication module, a user interface module, and a device control application.

[0188] like Figure 5 In the electronic device 1000 shown, the network interface 1004 can provide network communication functions; the user interface 1003 is mainly used to provide an input interface for the user; and the processor 1001 can be used to call the device control application stored in the memory 1005 to implement each step of the above-mentioned mountain bridge pier durability assessment method based on water-sand composite abrasion.

[0189] It should be understood that in some feasible embodiments, the processor 1001 may be a central processing unit (CPU). The processor may also be another general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, etc. The general-purpose processor may be a microprocessor or any conventional processor. The memory may include a read-only memory and a random access memory, and provides instructions and data to the processor. A portion of the memory may also include a non-volatile random access memory. For example, the memory may also store device type information.

[0190] In a specific implementation, the electronic device 1000 can execute the above-mentioned functions through its built-in functional modules. Figure 1 For the implementation methods provided in each step, please refer to the implementation methods provided in the above steps, which will not be repeated here.

[0191] The present invention also provides a computer-readable storage medium that stores a computer program and is executed by a processor to implement Figure 1 For the methods provided in each step, please refer to the implementation methods provided in the above steps, which will not be repeated here.

[0192] Any reference to memory, storage, database, or other media used in the various embodiments provided herein may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM).

[0193] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion, characterized in that: The steps include: S1. Calculate the abrasive rate of particles at the impacted bridge pier boundary based on the momentum theorem, establish a composite abrasive particle model that takes into account tangential cutting and normal impact, discretize the composite abrasive particle model using a smoothed particle element solver, and construct an initial calculation model for the abrasive rate of bridge piers in mountainous areas. S2. Determine multiple factors affecting the water-sand erosion of bridge piers. Based on the Box-Behnken design method, perform a multi-factor three-level orthogonal test simulation on the initial calculation model for the erosion rate of mountainous bridge piers. Based on the curve estimation theory, construct a preliminary calculation model for the water-sand erosion rate of mountainous bridge piers based on the composite abrasive model. Verify whether the precise solution of the model meets the requirements. If so, use the preliminary calculation model for the water-sand erosion rate of mountainous bridge piers based on the composite abrasive model as the final calculation model for the water-sand erosion rate of bridge piers, and execute step S4. Otherwise, execute the next step. S3. Identify the main control parameters that have the most significant impact on the abrasion rate. Based on the central composite design method, conduct a three-factor, five-level orthogonal test simulation on the initial calculation model for the abrasion rate of mountainous bridge piers. Based on the multivariate nonlinear regression theory, construct a final calculation model for the water-sand abrasion rate of mountainous bridge piers based on the composite abrasive model. S4. Based on the final water-sand erosion rate calculation model for mountain bridge piers based on the composite abrasive model and the hydrological operating conditions data at the bridge site, the annual erosion depth of the bridge piers is calculated, and based on the thickness of the concrete cover and the annual erosion depth of the bridge piers, whether the durability of the bridge piers can meet the service requirements is evaluated.

2. The method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion according to claim 1, characterized in that: Step S1 includes: S11: Considering the tangential cutting and normal impact effects, the tangential and normal rebound velocities of water-sand mixture particles after impacting the bridge pier are calculated based on the momentum theorem; S12: Calculate the abrasive rate of the particles at the boundary of the impacted bridge pier based on the tangential and normal rebound velocities of the water-sand mixture particles after impacting the bridge pier, and obtain a composite abrasive model that considers both tangential cutting and normal impact. S13: Discretize the composite abrasive particle model considering tangential cutting and normal impact in a smooth particle element solver, perform weighted summation using kernel function values, and calculate the total abrasion rate of the pier boundary particles within the solution time.

3. The method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion according to claim 2, characterized in that: In step S12, the composite abrasive model considering tangential cutting and normal impact is expressed by formula (7): （7） in, is the abrasion rate of the impacted pier boundary particles, 、 are the abrasive mass caused by the tangential cutting and normal impact of water-sand mixed particles on the pier boundary particles, is the concrete abrasion area, is the duration of abrasion; The abrasive mass caused by the tangential cutting and normal impact of the water-sand mixture particles on the pier boundary particles is calculated by equations (8) and (9): （8） （9） in, is the mass of sediment particles during the abrasion process, 、 are the hardness of sediment particles and the hardness of concrete, and are the tangential and normal rebound velocities of water-sand mixture particles, respectively; and are the tangential and normal velocities of the water-sand mixture particles before impact, respectively; is the compressive strength of concrete, 、 are cutting coefficient and deformation coefficient respectively; is the roundness coefficient of sediment particles; Calculated by formula (10): （10） in, is the critical wear coefficient.

4. A method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion according to any one of claims 1 to 3, characterized in that: The initial calculation model of the abrasion rate of mountainous bridge piers is expressed by formula (12): （12） in, The boundary particles of the pier Total abrasion rate; For each pier boundary particle Each water-sand mixture particle within the kernel function radius The rate of abrasion caused; is the kernel function value of the pier boundary particles; Represents water-sand mixed particles volume; Each pier boundary particle Each water-sand mixture particle within the kernel function radius The abrasion rate caused Calculated by formula (13): （13） in, 、 Water-sand mixed particles The particles at the bridge pier boundary The abrasive quality of tangential cutting and normal impact; The boundary particles of the pier Water-sand mixed particles The area abraded; is the duration of abrasion.

5. A method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion according to any one of claims 1 to 3, characterized in that: Step S2 includes: S21: Determine the factors affecting water-sand erosion of bridge piers through literature research, engineering experience, or field investigations; the factors affecting water-sand erosion of bridge piers include river depth, pier pile diameter, velocity of water-sand mixture particles before impact, sand content, sediment particle roundness coefficient, and concrete compressive strength; S22: Use the Box-Behnken design method to set three levels of low, medium, and high for each influencing factor. Use statistical software to automatically generate a Box-Behnken orthogonal simulation test plan, and specify the specific values ​​of each influencing factor under each experimental condition in the test plan; S23: Conducting tests or numerical simulations for each test scheme, and calculating and obtaining abrasion rate data under different combinations of influencing factors using the initial mountain bridge pier abrasion rate calculation model; S24: Using the multivariate nonlinear regression method, the erosion rate data under different combinations of influencing factors were fitted to establish a preliminary mathematical model between the erosion rate and the influencing factors, i.e., a preliminary water-sand erosion rate calculation model for mountain bridge piers based on a composite abrasive particle model; The preliminary calculation model of the water-sand erosion rate of mountain bridge piers based on the composite abrasive model in step S24 is expressed by formula (14): （14） in, is the abrasion rate of particles at the impacted pier boundary; For the depth of the river, is the diameter of the pier pile, is the velocity of water-sand mixture particles before impact, is the sand content, is the roundness coefficient of sediment particles, is the compressive strength of concrete; are the coefficients of each item, ; is a constant term, which is the model benchmark value and represents the basic abrasion rate when all influencing factors are zero; are the linear coefficients, representing the river depth , Pier pile diameter , velocity of water-sand mixture before particle collision , sand content , sediment particle roundness coefficient , concrete compressive strength The degree of linear effect on the abrasion rate; are interaction coefficients, representing the river depth and the diameter of the pier pile , velocity of water-sand mixture before particle collision , sand content , sediment particle roundness coefficient , concrete compressive strength , pier pile diameter Flow velocity before collision with water-sand mixture particles , sediment particle roundness coefficient , concrete compressive strength , velocity of water-sand mixture before particle collision and sand content , sediment particle roundness coefficient , concrete compressive strength , sand content and sediment particle roundness coefficient , concrete compressive strength , and the sediment particle roundness coefficient and concrete compressive strength The effect of interaction between them on the abrasion rate; is the quadratic coefficient, which indicates the nonlinear effect of each influencing factor and reflects the nonlinear change trend of the influencing factors on the abrasion rate. , Pier pile diameter , velocity of water-sand mixture before particle collision , sand content , sediment particle roundness coefficient , concrete compressive strength Nonlinear variation trend of abrasion rate.

6. A method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion according to any one of claims 1 to 3, characterized in that: Step S3 includes: Performing a sensitivity analysis or variance analysis on the preliminary water-sand erosion rate calculation model for mountain bridge piers based on the composite abrasive particle model, identifying at least three factors that most significantly affect the erosion rate as primary control parameters; the primary control parameters include the velocity of the water-sand mixture before impact, the diameter of the pier pile, and the compressive strength of the concrete; The central composite design method is used to set 5 levels for each main control parameter, automatically generate the test plan, and clarify the specific values ​​of each main control parameter under each test condition; Conducting tests or numerical simulations on each test plan using the initial mountain bridge pier abrasion rate calculation model to obtain abrasion rate data under different combinations of main control parameters; The multivariate nonlinear regression method was used to fit the abrasion rate data under different combinations of main control parameters, and the final mathematical model between the abrasion rate and the main control parameters was established, that is, the final water-sand abrasion rate calculation model for mountainous bridge piers based on the composite abrasive model.

7. The method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion according to claim 6, characterized in that: The final calculation model of water-sand erosion rate of mountain bridge piers based on the composite abrasive model is expressed by formula (15): （15） in, is the abrasion rate of particles at the impacted pier boundary; is the velocity of water-sand mixture particles before impact; is the compressive strength of concrete; is the diameter of the pier pile; is a constant term, which represents the basic abrasion rate when all main control parameters are zero; are the linear coefficients, representing the velocity of the water-sand mixture before the collision of particles , concrete compressive strength , Pier pile diameter The degree of linear effect on the abrasion rate; are the interaction coefficients, representing the velocity of water-sand mixture particles before impact. Compressive strength of concrete , velocity of water-sand mixture before particle collision Pier diameter , concrete compressive strength Pier diameter The effect of interaction between them on the abrasion rate; are quadratic coefficients, representing the velocity of water-sand mixture before particle collision , concrete compressive strength , Pier pile diameter Quadratic nonlinear effect on the wear rate.

8. A method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion according to any one of claims 1 to 3, characterized in that: The hydrological operating condition data at the bridge site in step S4 include the river depth under the hydrological operating condition, the diameter of the bridge pier pile, the velocity of the water-sand mixture before the collision, the sand content, the roundness coefficient of the sediment particles, and the compressive strength of the concrete; The annual erosion depth of the bridge pier in step S4 is calculated by formula (16): （16） in, is the annual erosion depth, Indicates the hydrological conditions, Indicates the The abrasion rate under different hydrological conditions, Indicates the The accumulated erosion time of various hydrological conditions is: is the density of concrete.

9. The method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion according to claim 8, characterized in that: The durability performance evaluation in step S4 is calculated according to formula (17): （17） in, is the concrete cover erosion time, represents the thickness of the concrete cover, Indicates the design service time; if the concrete cover abrasion time is greater than the design service time, it means that the durability of the pier can meet the design requirements within the design service time; If the abrasion time of the concrete cover is less than or equal to the design service time, it means that the durability of the pier does not meet the design requirements within the design service time and additional protective measures need to be taken.

10. A durability assessment system for bridge piers in mountainous areas based on water-sand composite abrasion, characterized by: The method for evaluating the durability of bridge piers in mountainous areas based on water-sand composite abrasion according to any one of claims 1 to 9 comprises: The first main module provides a user input interface for inputting pier structural parameters, material parameters, and hydrological operating parameters. Pier structural parameters include pier pile diameter and shape; material parameters include concrete compressive strength, density, and protective layer thickness; and hydrological operating parameters include river depth, velocity before water-sand mixture impact, sand content, sediment particle size, and sediment particle roundness coefficient. The second main module is used to calculate the abrasion rate of particles at the impacted bridge pier boundary based on the momentum theorem, establish a composite abrasive particle model that takes into account tangential cutting and normal impact, and discretize the composite abrasive particle model using a smoothed particle element solver to construct an initial calculation model for the abrasion rate of mountainous bridge piers. The third main module determines the multiple influencing factors of water-sand erosion of bridge piers, conducts a multi-factor 3-level orthogonal test simulation on the initial mountain pier erosion rate calculation model based on the Box-Behnken design method, constructs a preliminary mountain pier water-sand erosion rate calculation model based on the composite abrasive model based on the curve estimation theory, and verifies whether the model's precise solution meets the requirements. If so, the preliminary mountain pier water-sand erosion rate calculation model based on the composite abrasive model is used as the final pier water-sand erosion rate calculation model and executes the fifth main module; otherwise, executes the next step; The fourth main module is used to identify the main control parameters that have the most significant impact on the abrasion rate. Based on the central composite design method, a three-factor, five-level orthogonal test simulation is performed on the initial calculation model for the abrasion rate of mountainous bridge piers. Based on the multivariate nonlinear regression theory, a final calculation model for the water-sand abrasion rate of mountainous bridge piers based on the composite abrasive model is constructed. A fifth main module is used to calculate the annual erosion depth of the bridge piers based on the final water-sand erosion rate calculation model for mountainous bridge piers based on the composite abrasive model and the hydrological condition data at the bridge site; The sixth main module is used to evaluate whether the durability of the bridge pier can meet the service requirements based on the thickness of the concrete cover and the annual abrasion depth of the bridge pier concrete.

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