Method for selecting and predicting performance of estuary beach protection engineering structure

Abstract

The application discloses a kind of estuary beach protection engineering structure selection and performance prediction method, comprising: obtaining the basic data and design requirement of target estuary engineering section;Utilize the basic data to build estuary hydrodynamic-sediment coupling model;Physical pre-screening is carried out based on the basic data to determine the applicable engineering type;Combined with design requirements, the initial beach protection scheme is determined by multi-objective decision-making;Performance prediction data of the initial scheme under the preset working condition is obtained using the coupling model;Based on performance prediction data, the stability of the beach is evaluated to determine the final beach protection scheme.The present application introduces type pre-screening and long-term evolution optimization prediction, realizes the overall stability evaluation of the beach protection engineering, can improve the accuracy of sediment process simulation and reduce the long-term prediction calculation cost, and is suitable for estuary beach protection engineering.

Description

Technical Field

[0001] This invention relates to the field of waterway regulation and estuary protection technology, specifically to a method for selecting and predicting the performance of estuary protection engineering structures. Background Technology

[0002] As a confluence of runoff and ocean dynamics, estuaries are driven by runoff propulsion, tidal cycles, and wind and wave disturbances, resulting in complex water and sediment transport patterns. The selection of estuarine protection structures and performance prediction can be used to regulate the trajectory of water and sediment in estuaries, stabilize estuarine surface morphology, and ensure navigation channel dimensions.

[0003] Currently, the selection and prediction of estuary protection projects can be achieved using a two-dimensional planar hydrodynamic model combined with general sediment transport equations. In practical applications, this method often treats sediment transport as a steady-state equilibrium process, and the evaluation system tends to focus on single-point indicators such as the depth of local scour pits.

[0004] In the process of estuary management, the relevant technical system still needs to be improved in order to select structural schemes based on the complex and ever-changing dynamic environment and to quantitatively assess their long-term stability over a scale of several decades. Summary of the Invention

[0005] Purpose of the invention: In view of the above problems, the present invention discloses a method for selecting and predicting the performance of riverbank protection structures.

[0006] Technical solution: On the one hand, a method for selecting and predicting the performance of estuary protection structures, including:

[0007] Obtain basic data and design requirements for the target area;

[0008] Using basic data, a coupled hydrodynamic-sediment model of the estuary is constructed;

[0009] Pre-screening is performed based on basic data to determine applicable project types;

[0010] Based on the design requirements, a multi-objective decision-making process was conducted to determine the initial beach protection scheme;

[0011] The performance prediction data of the initially selected beach protection scheme under preset working conditions were obtained using a coupled model.

[0012] Based on performance prediction data, the stability of the beach surface is evaluated to determine the final beach protection scheme.

[0013] Beneficial effects: This invention introduces selection pre-screening and long-term evolution optimization prediction, realizing the overall stability evaluation of the beach surface of the beach protection project. It can improve the simulation accuracy of sediment process and reduce the long-term prediction calculation cost, and is applicable to estuary beach protection projects. Attached Figure Description

[0014] Figure 1 This is a flowchart illustrating a method for selecting and predicting the performance of a riverbank protection structure, as described in this application.

[0015] Figure 2 This is a flowchart illustrating a process for pre-screening based on basic data to determine the applicable project type, as described in this application.

[0016] Figure 3 This is a flowchart illustrating a process for determining a preliminary beach protection scheme through multi-objective decision-making, as described in this application.

[0017] Figure 4 This is a schematic diagram of a process for evaluating beach stability based on performance prediction data, as described in this application.

[0018] Figure 5 This is a schematic diagram of a process in the sediment transport correction module of this application, which corrects the sediment movement process based on the tidal period consolidation effect.

[0019] Figure 6 This is a schematic diagram illustrating the process of acquiring surrounding water and sediment environment evolution data under a long-term topographic evolution condition as described in this application. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first," "second," etc., in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a predetermined order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in sequences other than those illustrated or described herein. Furthermore, the terms "including" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] To address the aforementioned issues, the applicant conducted in-depth searches and analyses, and discovered:

[0023] In estuarine environments where strong tidal currents and high sediment content coexist, the periodic initiation and sedimentation patterns of sediment particles are significantly disturbed, resulting in low accuracy of traditional models in simulating the evolution of river channel scouring and deposition.

[0024] Meanwhile, predictions of long-term terrain evolution often face the dual problems of excessively high computational costs and nonlinear feedback distortion, resulting in significant subjectivity and lag in the engineering selection process.

[0025] On the one hand, existing technologies do not specifically incorporate the synergistic coupling effect of runoff, wind, waves and tides, and only consider the influence of water flow or tides. They do not accurately characterize the water and sediment movement law driven by the synergistic effect of runoff, tides and wind waves in the estuary area, resulting in a large deviation between hydrodynamic simulation and actual working conditions in the estuary.

[0026] On the other hand, without taking into account the characteristics of the estuary's sediment, which is mainly composed of fine sand and silt, the use of general sediment transport models and erosion resistance design standards makes it impossible to characterize the dynamic process of sediment suspension-transportation-deposition in the estuary. Furthermore, it fails to take into account common sense in engineering construction and does not adequately consider the adaptability of construction technology and the feasibility of foundation protection.

[0027] Furthermore, existing methods lack clear criteria for differentiated selection of common estuarine protection projects, making it difficult to adapt to the protection needs of different estuarine sections, such as high sediment content sections and strong tidal current sections. This results in poor adaptability of selection schemes, low accuracy of performance prediction, repeated iterations of engineering design, and increased engineering construction costs and risks.

[0028] In view of this, combined with Figure 1-6 This application is illustrated by the following embodiments.

[0029] The basic data in the following text includes topographic data, hydrological data, meteorological data, bottom physical parameter data, beach protection and navigation channel design parameter data, and beach surface historical evolution data of the target project section;

[0030] In some scenarios, historical synchronous observation data may also be included.

[0031] On the one hand, topographic data includes underwater topographic data and beach topographic data within the target area.

[0032] After acquiring terrain data, the discrete terrain sampling points can be processed using the Kriging interpolation method to obtain a continuous terrain field with a preset spatial resolution.

[0033] For example, spatial interpolation of the sampling point data is used to provide bottom boundary conditions for hydrodynamic simulation;

[0034] Optionally, the horizontal grid resolution used for interpolation is 2m×2m; this can be adjusted according to project requirements in practical applications.

[0035] Other values ​​are also not the only ones; they can all be set and adjusted by technical personnel, and will not be explained in detail below.

[0036] Based on this, an unstructured computational grid is generated according to the layout requirements of the beach protection project;

[0037] The local dimensions of the mesh are non-uniformly divided, that is:

[0038] In the proposed area for the beach protection project and the core area of ​​the waterway, the grid size will be increased; in some cases, the increased range can be set to 5-10m.

[0039] In open waters at the edge of the beach and away from the impact of engineering projects, the grid size can be set to 20-50m.

[0040] Furthermore, hydrological data, including runoff data and tidal data;

[0041] The runoff data specifically includes the multi-year average runoff, the proportion of flood and dry season flow distribution, flow velocity, and flow direction. In this step, the focus is on collecting extreme flow data during the flood and dry seasons to assess the stability of the bank protection structure under extreme hydraulic conditions.

[0042] Tidal data includes tidal level process sequences, tidal current velocity vectors for spring, mid, and neap tides, and tidal range distribution characteristics;

[0043] Furthermore, meteorological data, mainly involving wind and wave parameters, specifically including normal wind direction, strong wind direction, significant wave height, spectral peak period and wave direction, with a focus on acquiring extreme wave observation data during typhoons.

[0044] Substrate physical parameters, referred to as substrate parameters, can be obtained by conducting laboratory tests on substrate samples collected in the field. These parameters may include median particle size d50, characteristic particle size d90, clay content, dry density, permeability coefficient, critical erosion velocity, substrate bearing capacity, and consolidation characteristics. For example, clay content can be used to calculate the cohesion correction term in subsequent sediment transport models.

[0045] Design parameters for beach protection and navigation channels include navigation channel grade, design water depth, design service life, layout scope of beach protection works, and construction budget; these can also be referred to as design requirements.

[0046] Historical evolution data of the beach surface can specifically be topographic monitoring sequences of the target area over the past few years, used for model calibration and analysis of long-term evolution patterns.

[0047] Furthermore, performance prediction data includes structural mechanical response indicators and surrounding water and sediment environment evolution data under design conditions, extreme conditions, long-term topographic evolution conditions, and construction-specific conditions.

[0048] The estuary hydrodynamic-sediment coupling model includes:

[0049] (1). A two-dimensional planar hydrodynamic module based on the finite element method is used to simulate the flow field of a weakly density stratified estuary;

[0050] That is, the finite element method can be used to solve shallow water equations, and can handle unstructured computational domains including waterways, riverbank structures and mudflats.

[0051] (2). Estuary sediment transport correction module, which is used to correct the sediment transport process based on the tidal period consolidation effect, flocculation-wave turbulence competition mechanism and three-source combined bed shear stress, to obtain the corrected unit width sediment transport rate;

[0052] That is, a predetermined mechanism operator for the estuary can be introduced on the basis of the traditional non-equilibrium sediment transport model.

[0053] (3). Wind and wave module, used to simulate the propagation of wind and waves and their energy exchange with the hydrodynamic field;

[0054] That is, by exchanging real-time data with the hydrodynamic module, wave radiation stress is used as a source term input into the hydrodynamic control equation.

[0055] (4). Beach evolution simulation module, used to update the terrain based on the changes in the corrected unit width sediment transport rate, and obtain updated beach terrain data;

[0056] That is, the terrain elevation of each grid node is updated in real time by using the gradient change of the sediment transport rate per unit width and the discretized Exner equation.

[0057] Among them, the beach stability evaluation is to determine the long-term protective performance of the project by quantifying the overall balance of sediment on the beach surface within the protection area of ​​the beach protection project.

[0058] The combined bed shear stress of the three sources is the total shear stress obtained by vector combination after calculating the shear stress components of the three power sources of runoff, tidal current and wave.

[0059] Runoff velocity vector, turbulent dissipation rate, and bed shear stress during the resting period can be output by a two-dimensional planar hydrodynamic module.

[0060] The settling velocity of a single particle and the baseline critical erosion shear stress can be determined from the physical parameters of the substrate.

[0061] The maximum orbital velocity near the bottom of the wave and the wave turbulence dissipation rate can be output by the wind and wave module;

[0062] Near-bottom sediment concentration can be calculated using a coupled model;

[0063] Net sediment transport flux, also known as residual sediment transport flux;

[0064] Dimensionless stability index, also known simply as stability index.

[0065] As an example, a method for selecting and predicting the performance of estuary protection structures is provided, which includes the following steps:

[0066] Step 101: Obtain basic data and design requirements for the target area;

[0067] In this article, the target area specifically refers to the weakly density stratified estuarine region where runoff, wind waves, and tides interact.

[0068] The basic data obtained specifically includes topography, hydrology, meteorology, sediment parameters, and historical evolution records.

[0069] Substrate parameters can be obtained by testing fine sand and silt samples collected at the engineering site.

[0070] Design requirements include, for example, the expected goals of the beach protection project, the waterway grade, the design life, and the project budget constraints.

[0071] For example, a combination of on-site surveys and historical monitoring can be used to obtain the topographic evolution patterns of the target project section over the past few years, providing a data benchmark for subsequent model verification.

[0072] Step 102: Using the basic data, construct the estuary hydrodynamic-sediment coupling model;

[0073] Accordingly, the coupled model is built on a two-dimensional planar hydrodynamic framework to simulate water and sediment movement in estuaries under complex dynamic environments.

[0074] When building the model, terrain data is mapped to an unstructured computational grid, and sub-modules such as sediment transport, wind and wave propagation, and beach evolution are set up.

[0075] For example, the hydrodynamic module uses the finite element method to discretize the computational domain in order to handle the complex boundary conditions around the revetment structure.

[0076] Based on this, the constructed model can reflect the effects of runoff, tidal cycles, and wave disturbances on the initiation, suspension, and transport of sediment on the bed surface.

[0077] Step 103: Perform pre-screening based on basic data to determine the applicable project types;

[0078] Accordingly, intensity characteristics of tidal currents, runoff, and waves are extracted from the basic data, and the dominant dynamic factors of the target area are determined using dimensionless calculation methods.

[0079] For example, for beaches with strong wave action and weak tidal currents, the preliminary screening results may point to protective structures, such as breakwaters or submerged breakwaters.

[0080] That is, before making multi-objective decisions, engineering solutions that are incompatible with the dynamic environment should be eliminated.

[0081] In this step, the pre-screening is a process of conducting a preliminary assessment of the suitability of the revetment structure type based on the estuary dynamic characteristics.

[0082] Step 104: Within the scope of applicable engineering types, and in conjunction with design requirements, determine the preliminary beach protection scheme through multi-objective decision-making;

[0083] Among them, multi-objective decision-making refers to quantitatively scoring each candidate scheme by comprehensively considering hydrodynamic adaptation effect, mechanical safety performance, construction feasibility, economic indicators and ecological and environmental impact within the scope of applicable engineering types.

[0084] The evaluation indicators of different dimensions are standardized and weighted, and the relative closeness of each scheme to the ideal solution is calculated. The scheme with the highest comprehensive score is selected as the initial beach protection scheme.

[0085] Step 105: Use the coupled model to obtain the performance prediction data of the initially selected beach protection scheme under the preset working conditions;

[0086] For example, the geometric dimensions, layout location, and material properties of the initially selected beach protection scheme are imported into the coupled model as fixed boundaries.

[0087] The forecasting process covers a variety of preset operating conditions, including normal operating conditions, extreme weather conditions, long-term evolution conditions, and operating conditions during construction.

[0088] For example, the span of long-term evolutionary conditions can be set to 10-50 years.

[0089] Furthermore, the performance prediction data specifically includes the flow velocity distribution around the beach protection structure, the scalar field of scour and sedimentation thickness, the local scour depth, and the stress distribution of the structure.

[0090] Step 106: Conduct a beach stability evaluation based on performance prediction data to determine the final beach protection scheme.

[0091] That is, the sediment flux at each boundary of the beach control body is calculated using performance prediction data, and the scheme is graded and evaluated based on the net change in beach volume over an annual scale.

[0092] If the evaluation results show that the beach surface is in a state of erosion, the structural parameters of the initially selected beach protection scheme need to be iteratively optimized until the stability index reaches the requirements of dynamic equilibrium or siltation, so as to determine the final beach protection scheme.

[0093] This achieves a closed-loop design process from mechanism simulation to engineering effect evaluation.

[0094] Alternatively, step 104 can also be performed in the following manner:

[0095] A set of candidate solutions is determined based on the applicable engineering type, and a five-dimensional evaluation index system covering hydrodynamic adaptability, mechanical stability, economic rationality, ecological compatibility and construction feasibility is constructed for each candidate solution.

[0096] The evaluation indicators were made dimensionless, and the weights of each indicator were determined using the analytic hierarchy process.

[0097] Calculate the relative closeness of each candidate scheme to the ideal target corresponding to the design requirements, and determine the candidate scheme with the highest relative closeness as the preliminary beach protection scheme.

[0098] Alternatively, step 106 can also be performed in the following manner:

[0099] Define a beach surface control zone within the protected area of ​​the beach protection project;

[0100] Based on the sediment transport results in the performance prediction data, the net sediment transport flux of each open boundary of the control body within a preset time period is calculated to obtain the net change in beach volume.

[0101] The stability index is obtained by calculating the ratio of the net change in beach surface volume to the reference volume; where the reference volume is the total volume of the initial beach surface within the control area that is higher than the preset design reference level.

[0102] The stability of the beach surface is classified according to the numerical range of the stability index. When the classification result is erosion type, the structural parameters of the initially selected beach protection scheme are iteratively optimized until the stability index reaches the dynamic equilibrium type or siltation type level, and the final beach protection scheme is obtained.

[0103] When the classification result is either dynamic equilibrium type or siltation type, the preliminary beach protection scheme will be determined as the final beach protection scheme.

[0104] As a possible implementation, synchronization preprocessing is performed after acquiring the basic data.

[0105] Accordingly, time-series alignment was performed on runoff, tide, and wave data to remove outliers that deviated from physical logic, and trend analysis was used to supplement missing observation periods.

[0106] Furthermore, the process of generating the computational grid also includes steps for identifying and removing construction obstacle data.

[0107] Correspondingly, isolated reefs or shallow water construction obstacles in the area are identified through terrain scanning data, and boundary extraction or smoothing is performed on such areas during the grid generation stage, thereby making the numerical simulation more stable and providing geomorphic boundaries for construction adaptability assessment.

[0108] On the other hand, the optional implementation process for describing the sediment transport correction mechanism in estuaries is as follows:

[0109] Step 201, in the estuary sediment transport correction module, the sediment transport process is corrected based on the tidal period consolidation effect, including:

[0110] The effective consolidation time is determined based on the cumulative duration during which the bed surface shear stress is lower than the preset critical siltation shear stress during the resting flow period.

[0111] The consolidation enhancement factor was calculated using the effective consolidation time, and the clay content correction factor was calculated based on the clay content of the substrate in the basic data.

[0112] The reference critical erosion shear stress is multiplied by the consolidation enhancement factor and the clay content correction factor to obtain the modified critical erosion shear stress that varies dynamically with the tidal phase.

[0113] Due to the tidal movement in the estuary area, the sediment on the riverbed undergoes settling and compaction during the resting period. This step establishes a dynamic erosion criterion, which reflects the periodic changes in the seabed's resistance to erosion.

[0114] For example, τ _ce (t)=τ _ce_0 ×(1+η×(1-exp(-t _con (t) / T _con )))×(1+λ×(c _clay / (1-c _clay )) m1 );

[0115] Where, τ _ce (t) represents the modified critical erosion shear stress that varies dynamically with the tidal phase;

[0116] τ _ce_0 That is, the reference critical erosion shear stress, expressed by the formula τ _ce_0 =θ _cr ×(ρ _s -ρ _w θ is obtained by calculating )×g×d50. _cr That is, critical Shield _s Number; ρ _s That is, the density of sediment, ρ _w That is, the density of the water, g is the acceleration due to gravity, and d50 is the median particle size of the sediment.

[0117] η is the maximum consolidation enhancement factor;

[0118] t _con (t) is the effective consolidation time, defined as the time during which the bed shear stress remains below the critical silting shear stress within the current half-tidal cycle.

[0119] T _con That is, the characteristic consolidation timescale;

[0120] λ is the cohesive strengthening coefficient;

[0121] c _clay That is, the content of substrate clay particles;

[0122] m1, or empirical index, can be determined by technicians based on relevant experimental data.

[0123] The above improves the accuracy of siltation and erosion simulation.

[0124] Step 202, in the estuary sediment transport correction module, the sediment transport process is corrected based on the flocculation-wave turbulence competition mechanism, including:

[0125] The effective turbulent shear rate is calculated by combining the contributions of the combined flow turbulence dissipation rate and the wave turbulence dissipation rate.

[0126] The flocculation enhancement factor was calculated using near-bottom sand content and effective turbulent shear rate, and the sedimentation inhibition factor was calculated based on the relative relationship between near-bottom sand content and preset gel concentration.

[0127] The effective settling velocity is obtained by multiplying the settling velocity of a single particle by the flocculation enhancement factor and the settling inhibition factor, respectively.

[0128] Fine sand and silt in estuaries can flocculate or break up under the influence of saline-fresh water mixing and wind and wave disturbance; therefore, an effective turbulent shear rate is introduced to characterize the dual influence of water flow and waves on the floc structure.

[0129] That is, ω _s_eff =ω _s_0 ×((d _f / d _0 ) n_f-1 )×(1-C / C _gel ) n_h ;

[0130] In the formula, ω _s_eff That is, the effective settlement velocity, ω _s_0 That is, the settling velocity of a single particle, d _f That is, the floc particle size under dynamic equilibrium state, d _0 That is, the original particle size, n _f That is, the fractal dimension of the flocs, whose value varies depending on the density of the flocs; C represents the near-bottom sand content. _gelThat is, the gel concentration of the sediment, n _h That is, the resistance to settlement index.

[0131] floc particle size d _f The calculation formula is as follows, influenced by the effective turbulent shear rate:

[0132] In some scenarios, d _f =d _0 ×(k _A ×C / (k _A ×C+k _B ×((eps _c +α _w ×eps _w ) / ν) 0.5 )) 1 / (3-n_f) ;

[0133] In the formula, k _A With k _B That is, the empirical coefficient, eps _c That is, the turbulent dissipation rate of water flow, eps _w That is, the wave turbulence dissipation rate, α _w That is, the wave-flow turbulence interaction coefficient, and ν is the fluid kinematic viscosity.

[0134] This correction mechanism solves the problem of excessively rapid sediment settling under high sediment content conditions or the problem of slowed settling caused by floc breakage in windy and wave environments.

[0135] Step 203, in the estuary sediment transport correction module, calculate the combined bed shear stress from the three sources, including:

[0136] Explicitly separate the runoff velocity vector from the tidal flow velocity vector in the flow field;

[0137] The runoff velocity vector and the tidal flow velocity vector are superimposed to calculate the flow shear stress;

[0138] Wave shear stress is calculated by combining the maximum orbital velocity of the wave near the bottom, and the water flow shear stress and wave shear stress are combined to obtain the three-source combined bed shear stress.

[0139] In estuarine sections with strong runoff, hydrodynamics are jointly governed by seaward runoff and reciprocating tidal currents.

[0140] Therefore, by explicitly separating the runoff component, the accuracy of shear stress calculation under the three-source coupling background can be improved.

[0141] For example, τ _b_max =((τ _m +τ _w ×cos(Φ)) 2 +(τ _w ×sin(Φ)) 2) 0.5 ;

[0142] τ _c =ρ _w ×g / (C _z ) 2 ×|u _r +u _t | 2 ;

[0143] Above, τ _b_max For the three-source combined bed surface shear stress, τ _m τ is the average shear stress of the wave flow. _w This refers to wave shear stress. The calculation of flow shear stress depends on the synthesis of the runoff vector and the tidal current vector; C _z Let |u be the alignment coefficient. _r +u _t | represents the magnitude of the runoff velocity vector and the tidal flow velocity vector; Φ represents the angle between the wave direction and the combined flow direction.

[0144] In some scenarios, τ _m Based on τ _c The result after wave-current nonlinear enhancement.

[0145] It should be understood that this algorithm is used to capture the high shear stress environment experienced by bed sediments when runoff flooding and spring tides overlap.

[0146] In the above text, explicit separation can be achieved in some embodiments by extracting the tidal flow component through harmonic analysis of the tidal process and subtracting the tidal flow component from the total flow velocity to obtain the runoff component.

[0147] Alternatively, the average velocity during the resting period can be defined as the runoff component.

[0148] For areas with drastic topographic changes, the beach evolution simulation module also incorporates a bed slope correction term.

[0149] Accordingly, the additional sediment transport on the slope caused by gravity is introduced to correct the sediment transport rate vector per unit width.

[0150] For example, when the local slope between grid cells exceeds the angle of repose of the sediment, a local slump algorithm is automatically triggered to adjust the elevation of surrounding nodes to achieve stability of the bed morphology and avoid numerical calculation divergence at the edge of the revetment structure. This is suitable for simulating scour pits at the head of submerged dikes or groynes.

[0151] In the above scheme, the tidal period consolidation enhancement, flocculation-wave turbulence competition correction and three-source shear stress vector superposition calculation are introduced into the estuary sediment transport correction module. This captures the dynamic response characteristics of estuary fine sand under dynamic field and can be used to improve the accuracy of scour and deposition prediction under estuary conditions.

[0152] On the other hand, the structure pre-screening logic based on dynamic parameters is further described as follows:

[0153] Step 301: Before multi-objective decision-making, a mechanism pre-screening step is added, using the tidal current, runoff and wave characteristic values ​​extracted from hydrological and meteorological data to calculate dimensionless dynamic characteristic parameters.

[0154] Among them, mechanism pre-screening, also known as pre-screening, is a preliminary screening of the structural types of beach protection projects based on the dynamic characteristics of the target area before multi-objective scoring is carried out.

[0155] This is used to eliminate engineering solutions that are incompatible with the intended dynamic environment, thereby reducing subsequent resource consumption.

[0156] Dimensionless dynamic characteristic parameters can refer to quantitative indicators that can characterize the relative intensity between tidal currents, runoff, and waves.

[0157] This process can eliminate the interference of differences in absolute flow velocity or wave height between different estuaries on the selection logic, thereby improving the universality of the screening method.

[0158] Step 302: Perform pre-screening based on basic data to determine applicable project types, including:

[0159] The ratio of maximum tidal current velocity to average runoff velocity is calculated based on hydrological data to obtain the tidal current-runoff dominance ratio.

[0160] The wave-current energy ratio is obtained by calculating the ratio of the maximum near-bottom orbital velocity to the confluence velocity based on hydrological and meteorological data.

[0161] That is, R _tf =u _t_max / U _r ;

[0162] Pi _wc =u _b_w / (U _r +u _t_max );

[0163] In the above text, R _tf For the tidal flow-runoff dominance ratio, u _t_max U represents the maximum depth-average tidal current velocity during the spring tide period in the hydrological data. _r The cross-sectional average runoff velocity is given under multi-year average runoff conditions.

[0164] Pi _wc The wave-current energy ratio, u _b_w The maximum near-bottom orbital velocity of waves under normal wind and wave conditions; (U _r +u _t_maxThis reflects the background of the offsetting or enhancing effect of the combined hydrodynamic forces on the wave action;

[0165] The tidal-runoff dominance ratio is used to quantify the relative contributions of tidal and runoff dynamics to sediment transport in estuaries.

[0166] The wave-current energy ratio is used to quantify the dominant roles of wind and wave action and water flow action in the beach erosion process.

[0167] The confluence velocity is the sum of the average runoff velocity and the maximum tidal flow velocity.

[0168] Step 303: Based on the range of values ​​for the tidal current-runoff dominance ratio and the wave-current energy ratio, the beach protection project is matched as one of the following: a flow-guiding structure, a protective structure, or a combination of flow-guiding and protective structures, to obtain the applicable project type.

[0169] In this embodiment, the estuarine dynamic zone is divided into four categories based on the combination of two characteristic parameters, and corresponding revetment structures are matched accordingly.

[0170] The first type, when R _tf >1.5 and Pi _wc When the value is less than 0.3, it is determined to be a region of strong tidal current and weak wave.

[0171] The sediment transport in this area is mainly longitudinal, dominated by tidal currents. It is necessary to guide the tidal currents back into the channel to reduce the scouring of the beach. Therefore, the appropriate engineering type is a flow-guiding structure, specifically including groynes or longitudinal dikes.

[0172] The second type, when R _tf >1.5 and Pi _wc When the value is ≥0.3, it is identified as a region of strong tidal current and strong waves;

[0173] This area not only faces the longitudinal scouring of strong tidal currents, but also the sand-lifting effect of wind and waves. It is necessary to take into account both the functions of diversion and wave dissipation. Therefore, the suitable engineering type is a combined structure, specifically including the combined arrangement of groynes and submerged dikes.

[0174] The third type, when R _tf ≤1.5 and Pi _wc When the value is ≥0.3, it is determined to be a region of weak tidal current and strong wave.

[0175] Wave breaking caused by wind and waves in this area is the dominant factor in beach retreat. It is necessary to directly shield the wave energy. Therefore, the appropriate engineering type is a protective structure, specifically including beach breakwaters or submerged breakwaters.

[0176] The fourth type, when R _tf ≤1.5 and Pi _wc When the value is less than 0.3, it is identified as a region of weak tidal current and weak wave.

[0177] The region has relatively weak dynamics, with runoff-driven sediment replenishment and localized slight tidal range-induced transport being the main influencing factors. It is necessary to guide the water flow and provide basic protection, therefore the appropriate engineering type is a longitudinal dam or a revetment.

[0178] In some cases, for mountain stream estuaries with extremely high runoff variability, the calculation of the tidal current-runoff dominance ratio can also take into account the impact of large flow during the flood season.

[0179] Accordingly, the flood season average runoff velocity is introduced as a reference to calculate the flood season tidal current-runoff dominance ratio.

[0180] If the ratio of the flood season advantage to the multi-year average exceeds the threshold range, then a combined diversion and protection structure with higher mechanical stability should be prioritized in the selection process to adapt to the drastic seasonal fluctuations in dynamics.

[0181] Furthermore, when calculating the wave-current energy ratio, if the engineering area involves a high sand-containing section, the maximum orbital velocity of the wave near the bottom is corrected for fluid density.

[0182] Accordingly, by obtaining the measured near-bottom sediment content and updating the fluid kinematic viscosity parameters, the attenuation law of wave energy in the near-bottom region is recalculated, so that the pre-screening logic remains accurate when the sediment content changes the fluid dynamics characteristics.

[0183] In terms of selection decision-making, the dimensionless parameter pre-screening logic of tidal flow-runoff dominance ratio and wave-current energy ratio is used to achieve the matching of structural type and mechanism in the early stage of design, avoiding subjective blindness in selection and shortening the design iteration cycle.

[0184] In a further embodiment, the process of index quantification and weight allocation for a multi-objective decision-making system is explained.

[0185] Step 401 involves multi-objective decision-making, which involves comprehensively evaluating the pre-screened candidate solutions based on a pre-constructed five-dimensional evaluation index system.

[0186] The five-dimensional evaluation index system includes:

[0187] Hydrodynamic adaptability index; used to quantify the effect of beach protection projects on the regulation of estuarine flow field and wave energy. It is obtained by weighted summation of three sub-indicators: flow velocity return rate, wind and wave reduction rate, and beach scour and siltation control rate. Each sub-indicator is quantified based on the ratio of the actual value obtained from numerical simulation to the design target value.

[0188] Mechanical stability index; used to quantify the structural safety performance of beach protection projects under complex hydrodynamic and bottom conditions, it is composed of three sub-indices weighted together: overturning safety factor, sliding safety factor, and the ratio of the scour depth of the structural foundation to the burial depth of the foundation.

[0189] Economic rationality indicators; assess the full life-cycle cost of the project, including construction costs and subsequent maintenance costs;

[0190] Ecological compatibility indicators are determined by assessing the impact of the project on estuarine wetlands and aquatic habitats, specifically by calculating the habitat suitability index and the rate of change of flow velocity gradient.

[0191] Construction feasibility indicators; quantifying the difficulty of implementing the plan, including the adaptability of construction technology, the adaptability of construction water level windows, and the degree of navigation interference, using expert scoring to obtain quantitative values.

[0192] Step 402: Use the range standardization method to perform dimensionless processing on the original values ​​of all sub-indicators. The specific formula is as follows:

[0193] x' _ij =(x _ij -x _j_min ) / (x _j_max -x _j_min );

[0194] Above, x' _ij x represents the standardized value of the j-th metric in the i-th candidate solution. _ij This represents the original value of the indicator, x. _j_min Let x represent the minimum value of the j-th index among all candidate solutions. _j_max This represents the maximum value of the j-th index among all candidate solutions.

[0195] Step 403: Use the analytic hierarchy process (AHP) to determine the weights of each indicator.

[0196] Furthermore, pairwise comparison judgment matrices are constructed and assigned values ​​using the 1 to 9 scale method to calculate the weight allocation of each dimension index.

[0197] In one embodiment, the weight allocation is set as follows:

[0198] Mechanical stability weight: 0.3;

[0199] Hydrodynamic adaptability weight: 0.3;

[0200] Construction feasibility weight: 0.15;

[0201] Economic rationality weight: 0.15;

[0202] Ecosystem compatibility weight: 0.1.

[0203] Furthermore, a consistency check is performed on the judgment matrix, requiring a consistency ratio CR < 0.1. The calculation formula can be expressed as:

[0204] CR=(λ_max -n) / ((n-1)×RI);

[0205] Above, λ _max represents the largest eigenvalue of the judgment matrix, n represents the number of indicators, and RI represents the preset average random consistency index.

[0206] Based on this, the Euclidean distance between each candidate scheme and the positive and negative ideal solutions is calculated using the approximation ideal solution ranking method, and the relative closeness of each scheme is determined. The scheme with the highest relative closeness and that meets the minimum performance thresholds is selected as the initial beach protection scheme.

[0207] In some schemes, for engineering projects located in ecologically sensitive sections of river estuaries, dynamic weight adjustment rules can also be implemented. While meeting the safety constraints of each weight, the weight of the ecological compatibility indicator is increased. Alternatively, the weight of the economic rationality indicator can be reduced proportionally to adapt to the design requirements prioritizing ecology.

[0208] In the feasibility assessment, if the project involves construction during periods of strong tidal currents, a continuity weighting factor for the construction water level window is introduced into the expert scoring criteria. The cumulative duration for which the tidal current velocity within the construction water level window is below the equipment safety limit can be calculated to quantify the construction safety score, ensuring that the selected preliminary beach protection scheme is feasible under actual operating conditions.

[0209] In this embodiment, a dual-verification system for local scour depth is introduced to address the scour prediction distortion that may occur in numerical simulations when dealing with partial boundaries of revetment projects, such as groynes and submerged dike toes, due to limitations in turbulence model selection or mesh accuracy. Specifically:

[0210] Step 501, the process of obtaining the structural mechanical response index under the design conditions, can also be described as:

[0211] Based on hydrological data, meteorological data, and seabed physical parameter data, the tidal correction coefficient, wave correction coefficient, and seabed correction coefficient are calculated respectively. Based on the structural parameters of the initially selected beach protection scheme, the benchmark scour depth under the equivalent steady flow condition is calculated.

[0212] By using tidal correction coefficients, wave correction coefficients, and bottom sediment correction coefficients to correct the baseline scour depth, a semi-empirical predicted scour depth value is obtained.

[0213] Extract the numerical simulation scour depth output by the coupled model at the corresponding location on the structure;

[0214] And / or, establish a semi-empirical prediction formula for local scour depth as an independent verification method for numerical simulation, and compare and verify it with the numerical simulation results.

[0215] The above semi-empirical prediction formula specifically considers the combined effects of tidal currents, wind and wave disturbances, and the characteristics of silt / fine sand sediments in the estuary area. Its calculation expression is as follows:

[0216] d _s =d _s_0 ×K _T ×K _W ×K _sed ;

[0217] In the formula, d _s This is the predicted value for local scour depth; d _s_0 K represents the reference scour depth under equivalent steady-flow conditions. _T K is the tidal correction factor, used to characterize the enhancing effect of tidal current reciprocating motion on scouring; _sed K is a sediment correction factor used to correct for the influence of the content of fine sand, silt, and clay particles in the estuary on the local scour depth. _W This is a wave correction factor used to quantify the amplifying effect of waves on the initiation and transport of bottom sediment particles;

[0218] The benchmark scour depth can be determined differently based on the requirements of the current general technical standards for hydrological engineering and the corresponding calculation methods.

[0219] For example, for a groyne structure, d _s_0 The local scour calculation method for the head of a spur dike in a unidirectional flow non-cohesive soil riverbed can be used; for submerged dikes or revetment structures, d _s_0 The scour at the toe of the dike can be determined using a calculation method.

[0220] Furthermore, K _T =1+a _T ×(u _t_max / U _r ) b_T ×(1-exp(1-K _C / K _C_ref) );

[0221] K _C =u _t_max ×T _t / B _str ;

[0222] K _W =1+a _W ×(u _b_w / u _ce ) b_W ;

[0223] K _sed =(d _50_ref / d _50 ) c _s ×(1+ξ×(c_clay ) 0.5 );

[0224] Above, a _T With b _T The preset empirical coefficients can be calibrated through model experiments or regression testing using historical measured data. _t_max U represents the average tidal current velocity at maximum depth during spring tides. _r T is the multi-year average runoff velocity. _t For the tidal cycle, B _str K represents the characteristic width of the beach protection project. _C_ref For reference, it is usually taken as 10, a _W With b _W u is an empirical coefficient. _b_w The maximum orbital velocity near the bottom of the wave, u _ce d is the critical erosion friction velocity of the substrate. _50_ref For reference particle size, d _50 c is the median particle size of the substrate. _s ξ is the particle size correction index, ξ is the clay particle correction coefficient, and c _clay K represents the clay content in the substrate. _C It is a dimensionless parameter used to characterize the relative displacement of the tidal current through the structure within one tidal cycle.

[0225] After completing the above calculations, the obtained d _s The values ​​are compared with the numerical simulation scour depth output by the coupled model at the corresponding locations. This dual-verification system can identify abnormal deviations in the numerical simulation.

[0226] For example, in a submerged dike project at a high sediment content river estuary, if the deviation between the dike toe scour depth obtained by numerical simulation and the result calculated by the semi-empirical prediction formula is less than the preset verification threshold, then the numerical simulation result is deemed reliable.

[0227] Step 502: When the deviation between the semi-empirical formula prediction and the numerical simulation result exceeds a preset threshold, the model parameter verification is triggered.

[0228] In some cases, the preset threshold can be set to 20%;

[0229] When the comparison deviation exceeds the threshold, it is determined that the current numerical simulation parameters or physical submodules fail to accurately reflect the water and sediment movement characteristics of the target area.

[0230] At this point, the verification process is automatically triggered to perform a secondary calibration of the core parameters in the coupled model.

[0231] The objects to be reviewed include the critical erosion shear stress correction factor, the settling velocity correction parameter, and the bed surface roughness in the sediment transport module.

[0232] By adjusting the parameters, the numerical simulation results can be made to be consistent with the semi-empirical predictions, thereby ensuring that the accuracy of the scour prediction meets the engineering design requirements.

[0233] In other embodiments, the numerical simulation scour depth is further obtained using a calibrated coupling model;

[0234] When the deviation between the two does not exceed the preset threshold, the numerical simulation scour depth is determined as one of the structural mechanical response indicators under the design conditions.

[0235] For beach protection projects using new materials or special irregular structures, d _s_0 The calculation method can also be combined with the correction operator from model experiments. Accordingly, initial scour data of the new structure under a stable flow field are obtained through laboratory flume experiments, and the coefficients of the existing benchmark formula are fine-tuned accordingly, thereby ensuring the effectiveness of the dual-verification system in unconventional engineering scenarios.

[0236] Furthermore, when performing deviation comparisons, a spatial distribution consistency criterion can be introduced. In addition to comparing the maximum scour depth point, the morphological characteristics of the scour pits are also compared, including the major axis length and slope of the scour pits. If the depth deviation is within the threshold but the morphological difference is large, model mesh refinement or turbulence model parameter adjustment is also triggered to improve the spatial fidelity of the performance prediction data.

[0237] Implementing the above mechanism will help to achieve quantitative prediction of the local safety performance of estuary protection projects.

[0238] In one possible implementation, the workload reduction optimization process in long-term terrain evolution prediction can be achieved using the following method:

[0239] Step 601: Obtain data on the evolution of the surrounding water and sediment environment under long-term topographic evolution conditions, including:

[0240] Runoff, tidal and wave hydrodynamic elements are discretized into finite levels to construct multiple working condition combinations;

[0241] The probability of joint occurrence of each working condition combination is calculated based on historical synchronous observation data;

[0242] Short-term numerical simulations were performed on each combination of working conditions using a coupled model to obtain the spatial average sediment transport rate. The combined occurrence probability was multiplied by the spatial average sediment transport rate to obtain the sediment transport contribution weight of each combination of working conditions.

[0243] The working condition combinations are included into the representative working condition set one by one in descending order of sediment transport contribution weight, until the cumulative contribution reaches the preset threshold, and the representative working condition set is used to simulate long-term terrain evolution.

[0244] Correspondingly, for the long-term performance prediction of estuary protection projects, the computational cost of direct simulation over the entire time period is relatively high. Therefore, a representative condition reduction method was established to reduce the computational load while ensuring prediction accuracy.

[0245] For example, the process of discretizing into finite levels includes:

[0246] Runoff is discretized into four levels based on flow guarantee rate: low flow in dry season, normal flow in dry season, general flow in flood season, and high flow in flood season.

[0247] Tides are divided into three levels according to the magnitude of the tidal range: neap tide, mesopetition, and spring tide.

[0248] Waves are discretized into four levels based on their significant wave height: calm waves, normal waves, large waves, and typhoon waves; thus, a total of 48 working condition combinations are constructed.

[0249] Furthermore, the sediment transport contribution weight, used to quantify the contribution of each combination of working conditions to topographic evolution on a long-term scale, can be calculated as follows:

[0250] w _m =(P _m ×q _s_m ) / ∑ _i (P _i ×q _s_i );

[0251] Among them, w _m P represents the weight of the sediment transport contribution of the m-th working condition combination. _m q represents the joint occurrence probability of the m-th operating condition combination in historical synchronous observation data. _s_m ∑ represents the spatially average sediment transport rate scalar obtained from a short-term numerical simulation of the m-th working condition combination within a tidal cycle. _i This represents the summation of all operating condition combinations.

[0252] After obtaining the weights of each working condition combination, they are sorted from largest to smallest weight value. The working condition combinations are then sequentially added to a representative working condition set until the cumulative contribution of all working conditions in the set reaches a preset threshold. The preset threshold is set so that the representative working condition set can cover most of the terrain evolution dynamics.

[0253] Step 602, before simulating long-term terrain evolution using a representative set of working conditions, also includes:

[0254] The weights of each representative working condition in the representative working condition set are optimized and adjusted by the constrained least squares method so that the weighted net sand transport vector after the weight adjustment approaches the benchmark value of the full working condition combination.

[0255] The total predicted duration in the design requirements is allocated to each representative working condition according to the optimized weight, and the working condition sequence is arranged in the order of the natural season cycle.

[0256] After each working condition simulation is completed, the current bed surface topography is retained as the initial boundary condition for the next working condition to transmit feedback on topographic evolution.

[0257] The baseline value for the full range of operating conditions can be calculated based on the short-term numerical simulation results of all operating conditions.

[0258] In this step, mathematical optimization techniques are used to fine-tune the weights of the selected working conditions to eliminate residual errors caused by the reduction of the representative working condition set. Accordingly, the optimization process of the constrained least squares method can be expressed as the following formula:

[0259] min||∑ _m (α _m ×q _vec_m )-q _vec_base || 2 ;

[0260] In satisfying ∑ _m (α _m )=1 and α _m Find the optimal adjustment weight α under the constraint that α ≥ 0. _m .

[0261] Where, q _vec_m Let q be the net sediment transport vector for the m-th representative working condition. _vec_base Let |||| be the weighted average net sediment transport vector baseline value for the full range of operating conditions, |||| denotes the norm, and min denotes the function for finding the minimum value.

[0262] After obtaining the optimized weights, the total prediction time of the target is proportionally allocated to each representative working condition. During the simulation, a preset morphological acceleration factor is applied to each representative working condition to improve computational efficiency.

[0263] For example, if the morphological acceleration factor is set to S, then simulating the hydrodynamic process of one tidal cycle will generate S tidal cycles of topographic change.

[0264] Furthermore, the representative working conditions are sequentially arranged according to the natural seasonal cycle (e.g., dry season, flood season, typhoon season). After the simulation calculation of each representative working condition is completed, the bed elevation data of the current calculation unit is automatically saved and loaded as the initial terrain boundary for the next representative working condition simulation. This reproduces the feedback effect of terrain changes on the local hydrodynamic field.

[0265] Optionally, for extreme events occurring at a predetermined frequency, such as catastrophic floods, these events can be directly included as mandatory conditions in the representative condition set when constructing the combination of working conditions, without participating in the weighted ranking based on joint probabilities. This allows the long-term evolution prediction data to include the impact of extreme scour or large-scale siltation on the long-term safety of beach protection projects.

[0266] When performing weighted optimization, spatial partitioning constraints can also be introduced. That is, based on the different topographical sensitivity of the beach and the waterway, the net sediment transport vector deviation of different sub-regions is calculated separately, and a regional weight term is added to the objective function.

[0267] In the above text, in order to meet the needs of long-term prediction, a working condition reduction technique based on the weight of sediment transport contribution was adopted. While maintaining the high accuracy of the net sediment transport vector, the calculation time of long-term topographic evolution simulation was reduced, and the computing power problem of long-term evolution prediction was solved.

[0268] In one possible implementation, this application further includes:

[0269] Step 701: Obtain the structural mechanical response indices under each working condition, including:

[0270] The time history of surface hydrodynamic pressure of the beach protection project calculated by the coupled model is used as the load input.

[0271] Using the geometric parameters and seabed physical parameters of the initially selected beach protection scheme, an integrated structure-foundation model was constructed; a constitutive model based on seabed characteristics was used to calculate the stress distribution and strain of the initially selected beach protection scheme under load input.

[0272] Based on the calculated stress distribution and strain, the overturning safety factor and sliding safety factor of the initially selected beach protection scheme are determined.

[0273] Load mapping from the hydrodynamic module to the structural analysis module was achieved.

[0274] The specific operating conditions include design operating conditions, extreme flood or typhoon operating conditions, and construction period operating conditions. For the construction period operating conditions, the tidal flow velocity field within the construction water level window is simulated to determine whether the flow velocity at the construction platform is lower than the equipment safety limit.

[0275] Dynamic water pressure data, including dynamic pressure caused by water flow velocity and wave force caused by wave undulation.

[0276] During execution, the hydrodynamic pressure data of each calculation node on the surface of the beach protection structure in the time series are extracted from the coupled model;

[0277] A structure-foundation integrated model was constructed using the finite element method. During the modeling process, the structural shape of the submerged dike, groynes, or revetment was determined based on the geometric parameters of the initially selected beach protection scheme, and the geometric domain of the underlying foundation soil was established in conjunction with the bottom physical parameter data.

[0278] For example, the integrated model adopts a constitutive model based on substrate properties, which can be the Mohr-Coulomb constitutive model.

[0279] Parameters such as the internal friction angle, cohesion, and elastic modulus of the substrate are set to simulate the deformation characteristics of the soil under structural loads.

[0280] Under the action of load input, numerical iterative solution is performed to obtain the stress field and strain field inside the structure and the contact surface of the base;

[0281] Based on the obtained stress distribution, determine whether the structure has local stress concentration or material yielding.

[0282] The ratio of stabilizing resistance to instability driving force is calculated to determine the stability index of the structure. The calculation expression is as follows:

[0283] K _over =M _res / M _over ;

[0284] K _slide =(N×tan(φ _s )+c×A) / F _h ;

[0285] In the formula, K _over M represents the overturning safety factor. _res M represents the stabilizing moment acting on the beach protection structure. _over K represents the overturning moment caused by hydrodynamic loads. _slide Represents the anti-slip safety factor, N represents the total vertical pressure acting on the base, and φ _s The internal friction angle of the substrate is represented by , c represents the cohesion of the substrate, A represents the contact area of ​​the substrate, and F represents the internal friction angle of the substrate. _h It represents horizontal sliding force.

[0286] Optionally, for groynes using pile or caisson foundations, the integrated structure-foundation model also includes a detailed description of pile-soil interaction. Nonlinear spring elements can be used to simulate soil pressure along the pile sides, and the spring stiffness coefficients can be updated based on the physical parameters of the subgrade at different depths.

[0287] Furthermore, a seepage pressure compensation operator can be optionally introduced when calculating stress distribution. Correspondingly, the real-time water level data output by the coupled model is used to calculate the head difference between the inner and outer sides of the structure, and this difference is converted into seepage force applied to the internal elements of the integrated model. Based on this, the risk of overall stability degradation due to changes in seepage force within the revetment body under conditions of low water levels or sudden water level drops can be assessed.

[0288] In this embodiment, the above-described prediction process can be used to ensure that the final beach protection plan has a safety reserve.

[0289] In one possible implementation, the beach stability evaluation and sensitivity analysis optimization process specifically includes:

[0290] Optionally, the instantaneous normal sediment flux at each boundary point is obtained by performing a dot product between the single-width sediment transport rate vector at any point on the open boundary of the control volume and the unit normal vector pointing into the control volume.

[0291] The time integral of the dot product of the instantaneous normal sediment transport flux within the tidal cycle of the corresponding working condition is performed to obtain the tidal cycle residual sediment transport flux of each open boundary segment.

[0292] By combining the optimized weights of each representative working condition in the representative working condition set, the residual sediment transport flux is extended to the annual scale and weighted and summed to obtain the net change in beach volume at the annual scale.

[0293] Accordingly, the beach control volume is a spatially closed calculation area defined within the protection scope of the beach protection project; its boundary consists of the open boundary on the outer sea side, the shore side boundary, the lateral open boundaries on both sides, and the surface of the beach protection structure.

[0294] The surface of the revetment structure is considered an impermeable boundary with zero sediment flux.

[0295] For each representative working condition, the instantaneous sand transport data of all discrete nodes on each open boundary segment are extracted, and the net transport volume perpendicular to the boundary and pointing into the control body is calculated.

[0296] After calculating the dot product between the unit width sediment transport rate vector and the unit normal vector pointing into the control body, the dot product result is integrated over time within the tidal period of the corresponding working condition, and then spatially integrated along the length of the boundary segment to obtain the tidal residual sediment transport flux of each open boundary segment. The flux calculation expressions for each boundary segment are as follows:

[0297] F _res_m_γ =∫L _γ ∫0 T_t_m (q _s (x,y,t)×n _in_γ )dtdL;

[0298] In the formula, F_res_m_γ For the m-th representative working condition, the residual sediment transport flux during the tidal period of the boundary segment γ, ∫0 T_t_m This indicates the tidal period T under the corresponding operating condition. _t_m definite integral operations within, ∫ L_γ The corresponding spatial integral along the boundary segment γ, q _s (x,y,t) corresponds to the single-width sediment transport rate vector, n _in_γ The corresponding unit normal vector pointing inside the control body, L _γ The length of the boundary segment γ corresponds to d, and the differential operator corresponds to d.

[0299] Furthermore, after obtaining the throughput data for all representative operating conditions, the data is expanded into an annual-scale indicator using optimized weights, namely:

[0300] ΔV _Annual =T _year ×∑ _m=1 M (α _m ×∑ _γ∈Γ_open (F _res_m_γ / T _t_m ));

[0301] Where, ΔV _Annual The corresponding annual net change in beach surface volume, T _year Corresponding to the total number of seconds in a year, α _m The optimization weight corresponding to the m-th representative working condition, Γ _open The set of all open boundary segments corresponds to M, which represents the total number of working conditions.

[0302] Optionally, the stability index is obtained by calculating the ratio of the net change in beach volume to the reference volume;

[0303] The stability of the beach surface is classified into different levels based on the numerical range of the stability index. When the classification result is erosion type, the structural parameters of the initially selected beach protection scheme are iteratively optimized based on this (the obtained beach surface stability level) until the stability index reaches the dynamic equilibrium type or siltation type level.

[0304] The stability index measures the degree of drastic change in the beach elevation within the control area relative to its initial state. Its calculation expression is as follows:

[0305] Φ _b =ΔV _Annual / V _ref ;

[0306] Above, Φ _b That is, the dimensionless stability index, V _ref That is, to control the total volume of the body so that the initial beach surface is higher than the preset design reference surface.

[0307] For example, beach stability is divided into four levels based on the value of the stability index.

[0308] When Φ _b When the value is greater than 0.005, it is judged as a siltation type, indicating that the plan is conservative;

[0309] When Φ _b When the value is between -0.005 and 0.005, it is determined to be a dynamic equilibrium type, indicating that the scheme design is reasonable;

[0310] When Φ _b When the value is between -0.02 and -0.005, it is considered to be a mild corrosion type, and subsequent maintenance plans need to be strengthened.

[0311] When Φ _b When the value is less than -0.02, it is determined to be a severely corrosive type, and the scheme parameter optimization process must be triggered.

[0312] Based on this, before iteratively optimizing the structural parameters of the initially selected beach protection scheme, the following steps are also included:

[0313] Calculate the contribution ratio of the annualized net output corresponding to each open boundary to the annual net change in beach volume.

[0314] Based on the boundary location where the contribution ratio exceeds a preset threshold, the dominant direction of sediment loss is identified, and the priority direction for structural parameter optimization is determined accordingly.

[0315] The annualized net output is obtained by expanding the residual sediment transport flux on an annual scale.

[0316] Accordingly, boundary diagnosis can be performed to locate the main pathways of sediment loss.

[0317] For example, if calculations show that the annualized net output of the outer sea boundary exceeds a preset ratio, it is determined that the dominant direction of sediment loss is towards the sea, indicating that the current beach protection engineering scheme is insufficient in its function of wave dissipation or interception of sediment transport to the sea.

[0318] Accordingly, the optimization priority was determined to be strengthening the offshore interception structure, such as increasing the height of the submerged breakwater or extending the length of the beach protection dike. This diagnostic process provided a basis for subsequent parameter adjustments and reduced blind attempts.

[0319] In some embodiments, the structural parameters of the initially selected beach protection scheme are iteratively optimized, namely:

[0320] A perturbation within a preset range is applied to the selected structural parameters, and the rate of change of the stability index under the action of the perturbation is calculated by numerical difference to obtain the normalized sensitivity of each structural parameter.

[0321] The priority of parameter adjustment is determined according to the magnitude of the normalized sensitivity, and the structural parameters with the largest positive sensitivity are adjusted first to obtain the optimized structural parameter values.

[0322] Among them, normalized sensitivity is used to quantify the weight of the contribution of different structural design parameters to beach stability.

[0323] For example, the parameters can be fine-tuned and the model rerun to calculate the response strength of the stability index, as shown in the following expression:

[0324] S _ξ =((Φ _b_new -Φ _b_old ) / Φ _b_base ) / (Δξ / ξ _0 );

[0325] In the formula, S _ξ The normalized sensitivity of the structural parameter ξ can also represent the relative rate of change of the stability index when the parameter increases by 1%, Φ _b_new With Φ _b_old These are the stability indices before and after parameter fine-tuning, respectively, where Δξ is the parameter perturbation, and ξ... _0 Φ is the baseline value for the parameter. _b_base This is the stability index of the baseline scheme.

[0326] Based on the calculation results, all parameters to be optimized are automatically sorted by sensitivity.

[0327] Optionally, prioritize increasing parameters with positive and largest absolute values ​​of sensitivity, such as by increasing the length of the dike toe protection to improve beach stability.

[0328] For sections with complex and varied terrain, V _ref The calculation can be performed using a layered reference plane.

[0329] Accordingly, different design reference elevations are set for the channel area and the beach area respectively, so that the calculated stability index can reflect the protection effect of the beach protection project on different functional zones.

[0330] Furthermore, when conducting sensitivity analysis, a multi-parameter orthogonal experimental scheme can also be introduced.

[0331] Correspondingly, two or more related parameters, such as the spacing between groynes and the length of the dam, are fine-tuned simultaneously to analyze the synergistic effect between the parameters and their influence on the stability index.

[0332] The dimensionless stability index criterion based on the definition of the beach control volume elevates the engineering evaluation from a local performance indicator to a regional overall equilibrium criterion, which can reflect the degree of guarantee of the project for beach stability throughout the entire design life, making the scheme feasible and highly safe.

[0333] On the other hand, a specific application of the method of the present invention is provided in a scenario corresponding to the engineering scheme for the protection of riverbanks with high sediment content.

[0334] In this embodiment, the bottom sediment of the target estuary section is mainly composed of fine sand and silt, characterized by high sediment content, easy siltation, and easy suspension due to tidal disturbance.

[0335] Accordingly, underwater topographic data, beach topographic data, multi-year average runoff data, tidal process sequences, and wave observation data during typhoon seasons are acquired at a preset scale for this section.

[0336] The measured data of sediment physical parameters, such as median particle size d50, clay content, and dry density, were obtained.

[0337] The specific indicators required for the design include the flow velocity return rate, the wind and wave reduction rate of the embankment, the annual siltation control thickness of the navigation channel, and the beach retreat rate.

[0338] The obtained construction constraints clearly define the construction water level window as the mid-tide to low-tide level, and reserve a temporary navigation channel of predetermined width.

[0339] Furthermore, a two-dimensional planar hydrodynamic model is established based on planar two-dimensional hydrodynamic finite element analysis software, such as TELEMAC-2D software.

[0340] The model incorporates a critical erosion shear stress correction module related to tidal period consolidation, an effective settling velocity correction module based on the competition between flocculation and wave turbulence, and a three-source combined bed surface shear stress correction module.

[0341] Calibration was performed using measured data from several years prior to the project's construction, and the calculation errors for flow velocity, water level, and sediment content were all less than the error threshold.

[0342] Furthermore, feature values ​​are extracted from the acquired hydrological and meteorological data to calculate the tidal current-runoff dominance ratio and wave-current energy ratio.

[0343] Based on the preset dynamic characteristic parameter judgment logic, this section belongs to the weak tidal current and strong wave area, and the wave action is the dominant factor causing the beach surface to be eroded and retreated.

[0344] Accordingly, the applicable engineering type is determined to be a combination of protective structures consisting of shoal and submerged dikes.

[0345] Furthermore, a five-dimensional index scoring is performed on the candidate solutions within the applicable engineering type range.

[0346] Taking into account hydrodynamic adaptability, mechanical stability, construction feasibility, economic rationality, and ecological compatibility, the scheme with the higher comprehensive score was selected as the preliminary beach protection scheme.

[0347] The specific parameters in the plan can include the length, height, and slope of the low-submersion dike and the beach protection dike, respectively.

[0348] Construction techniques can also be selected in advance; for example, riprap can be combined with sump protection.

[0349] Furthermore, the geometric parameters of the initially selected scheme are imported into the coupled model to simulate the design conditions, extreme flood conditions, and construction period conditions, respectively.

[0350] The simulation results can be extracted, including flow velocity return rate, seawall wave reduction rate, annual siltation thickness of the navigation channel, and beach retreat rate.

[0351] Analysis shows that the overturning safety factors of both the submerged dike and the beach protection dike meet the safety design requirements.

[0352] Furthermore, a control volume for the beach surface, encompassing the protected area of ​​the beach protection project, is defined. The annual net change in beach surface volume is calculated using long-term topographic evolution data; a dimensionless stability index is then calculated.

[0353] In some scenarios, it is assumed that the calculated Φ _b The value is 0.003, indicating that the beach surface is in a dynamic equilibrium state.

[0354] Since all predicted indicators met the design requirements, the preliminary beach protection scheme was selected as the final beach protection scheme and implemented. This scheme not only has a short construction period and low cost, but also maintains good beach stability after many years of operation.

[0355] The above are just examples and not the only limitations. During implementation, the plan can be adjusted according to the specific conditions of the river section.

[0356] Other options may also collect data on construction conditions such as construction water level windows, navigation requirements, compatibility of construction equipment, and local building material reserves.

[0357] After being organized, it can be used to clarify construction constraints and provide boundary basis for engineering design.

[0358] The order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments.

[0359] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0360] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method for selecting and predicting the performance of estuary protection structures, characterized in that, include: Obtain basic data and design requirements for the target area; Using basic data, a coupled hydrodynamic-sediment model of the estuary is constructed; Pre-screening is performed based on basic data to determine applicable project types; Based on the design requirements, a multi-objective decision-making process was conducted to determine the initial beach protection scheme; The performance prediction data of the initially selected beach protection scheme under preset working conditions were obtained using a coupled model. Based on performance prediction data, evaluate the stability of the beach surface and determine the final beach protection scheme; The estuary hydrodynamic-sediment coupling model includes: a two-dimensional planar hydrodynamic module based on the finite element method, used to simulate the estuary flow field; an estuary sediment transport correction module, used to correct the sediment transport process based on the tidal period consolidation effect, the flocculation-wave turbulence competition mechanism, and the three-source combined bed shear stress; a wind and wave module, used to simulate wind and wave propagation and its energy exchange with the hydrodynamic field; and a beach evolution simulation module, used to update the terrain based on changes in the unit width sediment transport rate. The process involves pre-screening based on fundamental data to determine the applicable project types. This includes: calculating the ratio of the maximum tidal current velocity to the average runoff velocity based on hydrological data to obtain the tidal-runoff dominance ratio; calculating the ratio of the maximum near-bottom wave trajectory velocity to the confluence velocity based on hydrological and meteorological data to obtain the wave-current energy ratio; and matching the beach protection project to a flow-guiding structure, a protective structure, or a combination of flow-guiding and protective structures based on the range of values ​​for the tidal-runoff dominance ratio and the wave-current energy ratio to determine the applicable project types. The process of determining the initial beach protection scheme through multi-objective decision-making includes: constructing a five-dimensional evaluation index system covering hydrodynamic adaptability, mechanical stability, economic rationality, ecological compatibility, and construction feasibility; dimensionless processing of the evaluation indexes and determination of the weight of each index using the analytic hierarchy process; calculating the relative closeness of each candidate scheme to the ideal objective, and determining the candidate scheme with the highest relative closeness as the initial beach protection scheme.

2. The method according to claim 1, characterized in that, Performance prediction data includes structural mechanical response indicators and surrounding water and sediment environment evolution data under design conditions, extreme conditions, long-term topographic evolution conditions, and construction-specific conditions.

3. The method according to claim 1, characterized in that, Beach stability evaluation based on performance prediction data includes: Define a beach surface control zone within the protected area of ​​the beach protection project; Calculate the net sediment transport flux at each open boundary of the control volume within a preset time period to obtain the net change in beach volume. The stability index is obtained by calculating the ratio of the net change in beach volume to the reference volume. The stability of the beach surface is classified into different levels based on the numerical range of the stability index, and the structural parameters of the initially selected beach protection scheme are iteratively optimized accordingly.

4. The method according to claim 1, characterized in that, In the estuary sediment transport correction module, the sediment transport process is corrected based on the tidal period consolidation effect, including: The effective consolidation time is determined based on the cumulative duration during which the bed surface shear stress is lower than the critical silting shear stress during the resting period. The consolidation enhancement factor is calculated using the effective consolidation time, and the clay content correction factor is calculated based on the clay content of the substrate. The reference critical erosion shear stress is multiplied by the consolidation enhancement factor and the clay content correction factor to obtain the modified critical erosion shear stress that varies dynamically with the tidal phase.

5. The method according to claim 2, characterized in that, Acquisition of data on the evolution of the surrounding water and sediment environment under long-term topographic evolution conditions, including: Runoff, tidal and wave hydrodynamic elements are discretized into finite levels to construct several combinations of working conditions; The probability of joint occurrence of each working condition combination is calculated based on historical synchronous observation data; Short-term numerical simulations were performed on each combination of working conditions to obtain the spatial average sediment transport rate. The combined occurrence probability was multiplied by the spatial average sediment transport rate to obtain the sediment transport contribution weight of each combination of working conditions. The working condition combinations are included into the representative working condition set one by one in descending order of sediment transport contribution weight, until the cumulative contribution reaches the preset threshold. The representative working condition set is then used to simulate long-term terrain evolution.

6. The method according to claim 5, characterized in that, Before using a representative set of working cases to simulate long-term terrain evolution, the following is also included: The weights of each representative working condition in the representative working condition set are optimized and adjusted by the constrained least squares method so that the weighted net sand transport vector after the weight adjustment approaches the benchmark value of the full working condition combination. The total predicted duration is allocated to each representative working condition according to the optimized weight, and the working condition sequence is arranged in the natural seasonal cycle order. After each working condition simulation is completed, the current bed surface topography is retained as the initial boundary condition for the next working condition, and the topography evolution feedback is passed on.

7. The method according to claim 1, characterized in that, The acquisition of structural mechanical response indices under preset working conditions includes: The time history of surface hydrodynamic pressure of the beach protection project calculated by the coupled model is used as the load input. Using the geometric parameters and seabed physical parameters of the initially selected beach protection scheme, an integrated structure-foundation model was constructed. A constitutive model based on the characteristics of the bottom sediment was used to calculate the stress distribution and strain of the initially selected beach protection scheme under load input. Based on the calculated stress distribution and strain, the overturning safety factor and sliding safety factor of the initially selected beach protection scheme are determined.

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