Bridge foundation integrated protection structure and design method thereof

Abstract

This invention discloses an integrated bridge-embankment foundation protection structure and its design method in the field of water conservancy technology. It includes a bridge spanning a river and an embankment placed on the riverbank. The bridge has embankment piers within the embankment's front and rear protection zones. Isolation piles are installed at the embankment piers on both sides of the embankment. A protection zone is set outside the embankment, extending from the embankment toe to the vicinity of the embankment piers. The protection zone includes a cushion layer laid on the riverbed and connected to the embankment, with a thickness of 0.3m-0.5m. Gabion cages are laid on the cushion layer, with a thickness of not less than 1.0m. The width of the protection zone is determined comprehensively based on the scour depth at the embankment toe, the scour depth of the embankment piers, and the embankment grade. This invention proposes an integrated anti-scour measure for the scour of the embankment piers and the embankment foundation, and a "semi-enclosed" vibration isolation structure between the embankment piers and the embankment, thereby eliminating local hydraulic scour of the embankment piers and reducing the impact of bridge vibration on embankment safety, ensuring the stability and safety of the embankment and bridge structures.

Description

Technical Field

[0001] This invention relates to the field of water conservancy technology, specifically to an integrated protective structure for bridge and embankment foundations and its design method. Background Technology

[0002] When rivers flow through cities, it is often necessary to construct dikes or revetments along both banks to ensure flood control (or tide prevention). These dikes serve as a barrier against floods and tides, directly impacting the lives and property of people living along the riverbanks; therefore, ensuring the safety of dikes is of paramount importance. To guarantee the safety of dikes, water resources departments have established the management and protection scope of dike projects based on laws, regulations, and standards such as the Water Law, Flood Control Law, River Management Regulations, the "Design Code for Dike Engineering" (GB50286-2013), and the "Design Code for Dike Engineering Management" (SL / T 171-2020). The management scope of a dike project generally includes the dike body cross-section and the protective area. The width of the protective area on the backwater side of the dike is 30-20m for Class I dikes and 20-10m for Class II and III dikes. The protective area on the water-facing side of the dike generally extends 30-50m outward from the toe of the revetment slope. The protection range on the backwater side of the dike is determined according to the dike level, ranging from 300-50m. The protection range on the water-facing side is specifically demarcated by the dike management department based on river management needs and the actual project conditions. For large rivers, due to their high dike level, the dike body cross-section is often large, and the management and protection areas are also relatively large. With urban development and riverside development, it is inevitable that dike-related structures, such as bridges crossing the river, will be built. To avoid the adverse impact of cross-river bridges on the safety of dikes, theoretically, bridge spans should be as large as possible, and bridge piers should not be placed near the dike body or toe to prevent affecting the structural stability and safety of the dike body, as well as to prevent bridge piers from altering the water flow pattern and causing local erosion of the dike body and toe, thus threatening the safety of the dike. However, excessively large bridge spans are obviously uneconomical and would also greatly increase the difficulty of bridge design and construction. Therefore, when building cross-river bridges on large rivers, it is unavoidable that bridge piers will fall within the management or protection area of ​​the dike.

[0003] How to properly coordinate and handle the adverse effects of bridge piers located on the embankment within the embankment management area on the safety of the embankment is a major technical challenge. Currently, common solutions and their problems or defects are as follows: (1) Solution 1 is to increase the bridge span as much as possible, allowing the piers to be placed on the back slope of the embankment, while keeping the bridge piers on the water-facing side of the embankment as far away from the embankment management and protection area as possible, so as to avoid the bridge piers causing local water flow disturbance and local scouring of the embankment toe; this solution is usually applicable to situations where the embankment level is low, the embankment management area is small, and increasing the bridge span is economically feasible and technically feasible; (2) Solution 2 is to reconstruct the embankment project within the bridge's influence area, such as reconstructing the original earthen embankment into a reinforced concrete embankment, strengthening the embankment structure, and reducing the embankment cross section; this solution involves And the reconstruction of dikes involves complicated approval and construction procedures, high investment costs, and significant flood safety hazards during the flood season. It is generally not adopted easily. (3) Option 3 adopts remedial measures, using riprap, gabion stone cages, and concrete-filled geotextiles to protect the dike slopes and toes within the bridge's influence range. This option is currently more commonly used, but the protection of dike slopes and toes is mostly based on experience. There is often insufficient understanding of how bridge piers near the dike can alter the water flow structure in front of the dike, cause turbulent flow, and lead to local scouring. After a period of operation, the protective measures are often damaged or even fail due to local hydraulic scouring of the bridge piers near the dike.

[0004] Based on this, the present invention designs an integrated protective structure for bridge embankment foundations and its design method to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide an integrated protective structure for bridge embankment foundations and its design method, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an integrated bridge-embankment foundation protection structure, comprising a bridge spanning a river and an embankment placed on the riverbank. The bridge spanning the river has embankment piers installed on both sides of the embankment within its protection zone. Isolation piles are installed at the embankment piers on both sides of the embankment. A protection zone is set on the outer side of the embankment (water-facing side). The protection zone extends from the embankment toe to the embankment piers on both sides of the embankment, flowing with the water flow. The protection zone includes a cushion layer laid on the riverbed and connected to the embankment, with a thickness of 0.3m-0.5m. The protection zone also includes gabion cages laid on the cushion layer, with a thickness of not less than 1.0m. The protection zone is determined comprehensively based on the local scour depth at the embankment toe, the scour depth of the embankment piers, and the embankment grade.

[0007] Preferably, when the height difference between the protected areas is greater than or equal to 4m, a platform is set up for every 2-3m height difference; the platforms are connected with a slope of 1:1.5.

[0008] Preferably, the isolation piles are semi-enclosed structures, and high-pressure jet grouting piles or precast pipe piles are arranged at 180° on the side of the bridge pier adjacent to the embankment.

[0009] A preferred design method for an integrated protective structure for bridge embankment foundations includes the following steps:

[0010] Step 1: Based on the river topography, hydrology, and design data of cross-river bridges and embankments, establish a two-dimensional hydrodynamic mathematical model of the river, including cross-river bridges and embankments, and verify and calibrate the hydrodynamic mathematical model using measured hydrological data.

[0011] The second step involves using a validated hydrodynamic mathematical model to perform numerical simulations of tidal dynamics. For safety reasons, the model calculations do not consider tidal overflow. The higher-level tidal defense standard selected for both dike engineering and cross-river bridge engineering is used in the tidal calculations.

[0012] Step 3: Based on the numerical simulation results of tidal dynamics in Step 2, analyze and extract the hydrological and hydraulic parameters near the bridge piers on the embankment.

[0013] Step 4: Calculate the scour depth at the toe of the dike using the scour formulas (Equations 1 to 3) from the "Code for Design of Dike Engineering" (GB50286-2013). The required hydrological and hydraulic parameters are obtained using the hydrodynamic mathematical model from step three, including sediment bulk density. and median particle size Determined based on particle size analysis of on-site sediment samples.

[0014] (Equation 1)

[0015] (Equation 2)

[0016] (Equation 3)

[0017] In the formula: The depth of scour at the toe of the dike, in meters (m). The water depth in front of the dike is in meters (m). The near-shore vertical average velocity is given in m / s. is the initial velocity of sediment flow, m / s; n is related to the shape of the embankment slope in the plane, and is taken as n=1 / 4~1 / 6; Take the maximum flow velocity in front of the dike, in m / s; The median particle size of riverbed sediment, in meters; , The bulk density of silt and water, respectively, is expressed in kN / m³. The coefficient of non-uniformity of water flow is determined by the angle between the direction of water flow and the bank slope. Refer to Table 1 of the "Design Code for Dike Engineering" (GB50286-2013) to determine the answer.

[0018] Table 1. Coefficient of Non-uniformity of Water Flow Velocity

[0019]

[0020] Step 5: Calculate the scour depth of the bridge pier foundation using the formula for calculating the scour depth of the bridge pier near the embankment. From a safety perspective, the scour depth of bridge piers near the embankment... Considering the typical scour depth of bridge piers near the embankment. and local scour depth The adverse effects of the superposition, namely = + h n and h b The scour formulas (Formulas 4 to 17) for bridge piers near the embankment in the "Specifications for Hydrological Survey and Design of Highway Engineering" (JTG C30-2015) were used for calculation. The river characteristic parameters required for the calculation were determined based on the actual situation of the river where the project is located through surveying and mapping. The shape parameters of the bridge piers near the embankment were determined based on the bridge design data. The hydrological and hydraulic parameters were obtained based on the bridge design data and the third step of the hydrodynamic numerical model.

[0021] (1) Typical scour depth of bridge piers near embankments calculate

[0022] (Equation 4)

[0023] (Equation 5)

[0024] (Equation 6)

[0025] In the formula:

[0026] —The maximum water depth (m) under the bridge after typical scouring;

[0027] —Design flow rate (m³ / s);

[0028] —The design flow rate (m³ / s) passing through the riverbed under the bridge is taken as Qp when the riverbed can be expanded to cover the entire bridge;

[0029] —Design flow rate (m³ / s) of the river channel under natural conditions;

[0030] —Design flow rate of the riverbed under the bridge under natural conditions (m³ / s);

[0031] —Width of the river channel in its natural state (m);

[0032] — Width of the river channel (m) within the bridge length range; when the river channel can be widened to the full length of the bridge, the total length of the bridge span shall be used.

[0033] —Channel width (m) under the bed-forming flow rate; for complex riverbeds, the channel width at the flat beach water level can be taken.

[0034] λ — At the design water level, Within the width range, the ratio of the total water-blocking area of ​​the bridge piers adjacent to the embankment to the water-passing area;

[0035] μ——Lateral compressibility coefficient of water flow near bridge piers;

[0036] —Maximum water depth in the riverbed;

[0037] —Unit width flow concentration coefficient, changes in the piedmont area, wandering, and wide-shoal river sections When >1.8, The value can be 1.8;

[0038] —The average water depth of the channel under the bed-forming flow rate (m). For complex riverbeds, the average water depth of the channel at the flat beach water level can be taken.

[0039] Lateral compressibility coefficient μ of water flow near bridge piers

[0040] Table 2

[0041]

[0042] Note: 1. The coefficient μ refers to the reduction factor of the water passage area on the side of the pier due to the stagnation zone formed by the vortex.

[0043] 2. When the net span of a single span L0 > 45m, it can be calculated using μ = 1 - 0.375Vs / L0. For bridge spans with unequal spans, the average value of μ for each span can be used. When the net span of a single span L0 > 200m, μ≈1 is taken.

[0044] Revised official

[0045] (Equation 7)

[0046] In the formula:

[0047] —The net width of the bridge openings in the riverbed (m) is the net width of the bridge openings when the riverbed under the bridge can be expanded to the full bridge.

[0048] —Average water depth in the riverbed under the bridge (m);

[0049] —Average particle size of riverbed sediment (mm);

[0050] —A coefficient related to sediment content during the flood season;

[0051] You can choose according to Table 3.

[0052] Coefficients related to sediment content during the flood season value

[0053] Table 3

[0054]

[0055] Note: Sand content The average monthly maximum sediment concentration during the flood season in previous years was used.

[0056] The scour depth of bridge piers near the embankment is generally calculated according to (Equation 8).

[0057] = - (Equation 8)

[0058] In the formula:

[0059] — Typical scour depth (m) of bridge piers near embankments;

[0060] —The maximum water depth (m) under the bridge after typical scouring;

[0061] —Water depth under the bridge before scouring (m);

[0062] (2) Local scour depth calculate

[0063] When the bottom surface of the pier cap is lower than the general scour curve, it should be calculated as the superstructure; when the bottom surface of the pier cap is higher than the water surface, it should be calculated as a frame pier; the relative height of the pier cap bottom surface... At that time, scour depth Calculate according to (Equation 9):

[0064] (Equation 9)

[0065] (Equation 10)

[0066] (Equation 11)

[0067] (Equation 12)

[0068] (Equation 13)

[0069] (Equation 14)

[0070] (Equation 15)

[0071] When using simplified calculations for general scouring:

[0072] (Equation 16)

[0073] When using modified calculations for general scouring:

[0074] (Equation 17)

[0075] In the formula:

[0076] —Local scour depth (m);

[0077] —The relative height of the bottom surface of the pier cap shall be calculated in accordance with Appendix C of the "Specifications for Hydrological Survey and Design of Highway Engineering" (JTG C30-2015);

[0078] —The shape coefficient of a single pile is determined according to the numbering of piers 1, 2, 3, and 5 (if most are cylindrical). (can be omitted)

[0079] —Pile group coefficient;

[0080] —Reduction factor for submerged columns;

[0081] φ——Pile diameter (m);

[0082] —The calculated width of the bridge piers near the embankment shall be determined in accordance with Appendix C of the "Specifications for Hydrological Survey and Design of Highway Engineering" (JTG C30-2015);

[0083] —Pier type coefficient;

[0084] —The reduction coefficient of the pier cap is selected according to Appendix C of the "Specifications for Hydrological Survey and Design of Highway Engineering" (JTG C30-2015);

[0085] —Influence coefficient of riverbed particles;

[0086] —The general scouring velocity of the flow before the pier is 0.1 to 6 m / s;

[0087] —Initial flow velocity of sediment in the riverbed (m / s);

[0088] —Initial flow velocity of sediment in front of the pier (m / s);

[0089] --index;

[0090] —Average particle size of riverbed sediment (mm);

[0091] —The maximum water depth (m) under the bridge after typical scouring;

[0092] —The width of the pile group distributed perpendicular to the direction of water flow;

[0093] —The number of rows of piles;

[0094] —Average flow velocity in the river channel (m / s);

[0095] —Average water depth of the river channel (m).

[0096] Step 6: Determine the safe distance B, taking into account a certain safety margin and the maximum impact area of ​​bridge and embankment scour; and The maximum value of h is taken as the most unfavorable scour depth. The stable slope ratio i of the scour pit is determined based on the riverbed composition and engineering experience. The maximum local scour impact range after the bridge piers are installed near the levee is L = h / i. Considering a certain safety margin ΔB, the safe distance to avoid the impact of bridge pier scour on the levee can be determined as B from the levee toe to the outside of the levee, B = L + ΔB. ΔB is determined according to the levee engineering level. For Class 1 levees, ΔB is 20m; for Class 2 and 3 levees, ΔB is 10m; for Class 4 and 5 levees, ΔB is 5m. The stable slope ratio i of the scour pit is determined based on the riverbed composition and engineering experience. For example, for a pebble riverbed, the stable slope ratio i of the scour pit can be 1 / 2; for a sandy riverbed, the stable slope ratio i of the scour pit can be 1 / 3.

[0097] Step 7: Determine whether the scouring of the bridge piers and the toe of the dike affects the safety of each other's foundations and whether integrated protection is required. The specific determination method is as follows: (1) When B≥B0 (the maximum influence range B of the scouring of the bridge piers and the toe of the dike is greater than or equal to the distance B0 between the bridge piers and the toe of the dike), the scouring caused by the two may have an adverse effect on the safety of each other, and integrated protection of the bridge and dike foundations is required; (2) When B<B0 (the maximum influence range B of the scouring of the bridge piers and the toe of the dike is less than the distance B0 between the bridge piers and the toe of the dike), it is considered that the scouring caused by the two does not affect the safety of each other, and integrated protection of the bridge and dike foundations is not required.

[0098] Step 8: Determine the protection range, i.e., determine the protection width B. W Heshun River protection length B L ; Protective width B W The protection length B extends along the bridge centerline from the toe of the flood control dike into the river to the bridge pier adjacent to the dike, as shown in Formula 18; the protection length along the river is B. L Determined according to the dike grade, for a Class 1 dike project, B L Taking a 300m range upstream and downstream of the bridge, for a Class 2 levee, B L For other levels of levees, within a 150m range upstream and downstream of the bridge, B L Take a 50m range upstream and downstream of the bridge;

[0099] B W =B0+b+B (Equation 18)

[0100] B = (h / i + △B) (Equation 19)

[0101] h=max( , (Equation 20)

[0102] In the formula: B W B0 is the width of the protected area, in meters; B0 is the distance between the bridge pier adjacent to the dike and the toe of the dike, in meters; b is the width of the bridge pier adjacent to the dike, in meters; B is the safe distance considering a certain safety margin and the maximum impact area of ​​bridge and dike scour, in meters; h is the unfavorable scour depth, in meters. and These are the scour depths at the toe of the dike and the scour depths at the bridge piers adjacent to the dike, respectively, in meters (m).

[0103] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention addresses the problem that the piers of cross-river bridges located on the water-facing side of the embankment, which may cause scour at the embankment toe and vibration of the embankment body, and have an adverse effect on the overall anti-sliding stability of the embankment. The present invention proposes an integrated anti-scour measure for the scour of the piers and the foundation of the embankment, and sets up a "semi-enclosed" (or "semi-enclosed") vibration isolation structure between the piers and the embankment, thereby eliminating local hydraulic scour of the piers and reducing the impact of bridge vibration on the safety of the embankment, and ensuring the stability and safety of the embankment and bridge structures.

[0104] This invention presents a scientific approach to integrated bridge-embankment foundation protection, proposing a design method that places the cross-river bridge and embankment project within the same hydrodynamic model for coupled analysis. This method realistically simulates the impact of adjacent bridge piers on water flow patterns and their scouring effect on the embankment toe, breaking away from the limitations of traditional separate approaches and achieving integrated safety design in the boundary area. In practical operation, this method simultaneously calculates the scouring depth of the embankment toe and adjacent bridge piers based on the "Elevation Engineering Design Code" and the "Highway Engineering Hydrological Survey and Design Code," combined with hydrological parameters provided by a refined model. The method uses the most unfavorable superposition value to ensure the scientific validity and safety of the calculation. By introducing the concepts of "most unfavorable scouring depth" and "stable slope," this method can scientifically calculate the quantitative impact range of the adjacent bridge pier construction on the embankment toe and sets a safety margin, transforming the judgment of "whether the adjacent bridge pier affects the embankment" from qualitative to quantitative. Furthermore, through clear judgment criteria and protection range calculation formulas, the complex fluid-structure interaction problem is simplified into intuitive engineering parameters, significantly improving the standardization and operability of the design. Ultimately, by accurately calculating and determining the protection range, we can avoid the waste caused by over-protection and set differentiated safety margins for different dike levels, thus achieving a balance between engineering safety and economy.

[0105] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0106] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0107] Figure 1 This is a schematic diagram of the integrated protection structure for bridge and embankment foundations of the present invention;

[0108] Figure 2 This is a cross-sectional schematic diagram of the integrated protective structure for bridge and embankment foundations of the present invention;

[0109] Figure 3 The diagram shows the vibration isolation effect (dike deformation cloud map) of different vibration isolation schemes for bridge piers near the dike based on ANSYS software according to the present invention.

[0110] Figure 4 This is a diagram showing the effect of different isolation depths (dike deformation cloud map) based on ANSYS software according to the present invention.

[0111] In the attached diagram, the components represented by each number are as follows:

[0112] 1-Cross-river bridge, 2-Bridge pier near the embankment, 3-Elevation, 4-Protective zone, 5-Isolation pile Detailed Implementation

[0113] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0114] Please see Figure 1-4 This invention provides a technical solution for an integrated protective structure for bridge embankment foundations and its design method:

[0115] Step 1: Establish a two-dimensional hydrodynamic mathematical model of the river where the bridge is located.

[0116] Collect river topography, hydrology, and design data of cross-river bridges and embankments to establish a two-dimensional hydrodynamic mathematical model of the river that includes cross-river bridges and embankments.

[0117] The hydrodynamic mathematical model was developed using Mike21 software. It is based on the Navier-Stokes equations, which assume incompressibility and uniform distribution of Reynolds values, and is subject to the Boussinesq assumption and the assumption of hydrostatic pressure.

[0118] The two-dimensional non-steady shallow water equations are as follows:

[0119] (Equation 21)

[0120] (Equation 22)

[0121] (Equation 23)

[0122] In the formula: For time; Coordinates are in the Cartesian coordinate system; Water level; The depth of still water; Total water depth; They are respectively Velocity component in the direction; , These are the average flow velocities based on water depth in the x and y directions, respectively; Pa is the local atmospheric pressure. This refers to the density of water under standard temperature and pressure. , They are along Shear stress in the direction; , They are along Undercut stress in the direction; It is the Coriolis force coefficient. , This is the Earth's rotational angular velocity. The latitude is the local latitude. ρ is the acceleration due to gravity; ρ is the density of water. , , These are the radiation stress components; , This is a horizontal viscous stress term. For source and sink items, For the source of the water flow in Flow velocity in the direction.

[0123] The hydrodynamic model ranges from the upstream main stream control hydrological station section (or downstream of the dam) to the downstream river mouth hydrological station or tide gauge station section.

[0124] The hydrodynamic model adopts an unstructured triangular mesh. The mesh size is determined comprehensively based on the accuracy of the modeling topographic map, the degree of topographic relief, and the size of important river-crossing structures. The mesh size should be comparable to the interval of elevation measurement points in the modeling topographic map. The local mesh should be densified in areas with drastic topographic relief and important river-crossing structures.

[0125] The roughness of the hydrodynamic model can be determined based on experience, taking into account factors such as river type, riverbed morphology, riverbed composition, and distribution of river-related structures, and then finalized through model verification and adjustment.

[0126] The upper boundary of the hydrodynamic model is set at the starting section of the main stream and tributary, and the upper boundary adopts the flow rate. The lower boundary of the model is set at the section where the hydrological (level) station or tide level station is located downstream of the confluence section of the waterway, and the lower boundary adopts the water (tide) level.

[0127] The hydrodynamic mathematical model needs to be validated using measured hydrological data. Validation mainly includes the flow rate and diversion ratio of each channel, water (tidal) level, flow velocity, and flow direction. This is primarily achieved by adjusting the grid file, model roughness, and initial water level field boundaries to ensure that the differences between calculated and measured values ​​at each hydrological station meet the error requirements. The error between the model's calculated and measured values ​​should meet the relevant requirements of the "Technical Specification for Simulation Tests of Water Transport Engineering" (JTS-T 231-2021).

[0128] Step 2: Using a validated hydrodynamic mathematical model, perform numerical simulation calculations of tidal dynamics. For safety reasons, the model calculations do not consider tidal overflow. The calculation standard is selected as the higher of the tidal defense standards for the levee project and the cross-river bridge project. In this embodiment, the bridge's design flood control standard is a 300-year return period, and the levee project's design flood control standard is a 50-year return period; therefore, the flood standard used in the hydrodynamic numerical simulation calculations is a 300-year return period.

[0129] Step 3: Based on the numerical simulation results of tidal dynamics in Step 2, analyze and extract the hydrological and hydraulic parameters near the bridge piers on the embankment.

[0130] Step 4: Calculate the scour depth at the toe of the dike using the scour formulas (Equations 1 to 3) from the "Code for Design of Dike Engineering" (GB50286-2013). The required hydrological and hydraulic parameters are obtained using the hydrodynamic mathematical model from step three, including sediment bulk density. and median particle size Determined based on particle size analysis of on-site sediment samples.

[0131] Example: Design of water depth before flood subsidence. The maximum flow velocity in front of the dike is 11.18m. The velocity is 2.57 m / s; based on geological surveys and sediment data, the median particle size of the riverbed sediment is... The density of sediment and water is 0.00032m. They are 2650 KN / m³ and 1000 KN / m³, respectively; The coefficient of non-uniformity of water flow is determined by the angle between the direction of water flow and the bank slope. Refer to Table 1 of the "Code for Design of Dikes" (GB50286-2013) and select 1. Calculate the average near-shore vertical velocity. The initial velocity of the sediment flow is 2.57 m / s. The value is 0.507 m / s; considering the unfavorable scouring angle, n is taken as 1 / 4, and the maximum scouring depth at the toe of the dike is calculated to be 5.59 m.

[0132] Step 5: Calculate the scour depth h2 of the bridge pier foundation using the formula for calculating scour depth. The scour depth h2 of the bridge pier foundation considers a typical scour depth. and local scour depth h b The adverse effects of the superposition, namely = + h n and h b The scour formulas (Formulas 4 to 17) for bridge piers near the embankment in the "Specifications for Hydrological Survey and Design of Highway Engineering" (JTG C30-2015) were used for calculation. The river characteristic parameters required for the calculation were determined based on the actual situation of the river where the project is located through surveying and mapping. The shape parameters of the bridge piers near the embankment were determined based on the bridge design data. The hydrological and hydraulic parameters were obtained based on the bridge design data and the third step of the hydrodynamic numerical model.

[0133] The embodiment uses the modified formula (Equation 7) to calculate the general scour depth h of the bridge piers adjacent to the embankment. n Based on the numerical simulation results and bridge survey and design data, using equations (4 to 17), we can obtain: Q under the design flood. p Q2 is 33792 m³ / s, A is 24469 m³ / s. d B is 1.1. cj It is 762m, h cm It is 16.40m, h cq The value is 12.35m, μ is 0.98, and E is 0.46. It is 0.00032m, h p It is 16.52m, h n The depth is 4.17m. Furthermore, based on the numerical model calculation results and bridge survey and design data, the local scour depth of the bridge piers adjacent to the embankment is calculated using equations (4 to 17). We can obtain: =1, It is 2.72. The value is 0.99, and the diameter (φ) is 1.5m. It is 2.15. It is 0.05. It is 2.9m. It is 2.29. It is 0.55 m / s. It is 0.22 m / s. It is 2.47 m / s. It is 0.74. The depth is 9.05m. Therefore, the scour depth of the bridge pier near the embankment in the embodiment is [value missing]. = + =4.17+9.05=13.22m.

[0134] Step 6: Determine the safety distance B, taking into account a certain safety margin and the maximum impact area of ​​bridge and embankment scour. (Take...) and The maximum value of h is taken as the most unfavorable scour depth. The stable slope ratio i of the scour pit is determined based on the riverbed composition and engineering experience (e.g., for a pebble riverbed, the stable slope ratio i can be 1 / 2; for a sandy riverbed, the stable slope ratio i can be 1 / 3). Then, the maximum local scour impact range after the bridge piers are installed on the embankment is L = h / i. Considering a certain safety margin ΔB, the safe distance to avoid the impact of bridge pier scour on the embankment can be determined as B from the embankment toe to the outside of the embankment, B = L + ΔB. ΔB is determined according to the embankment engineering level. For Class 1 embankments, ΔB is 20m; for Class 2 and 3 embankments, ΔB is 10m; and for Class 4 and 5 embankments, ΔB is 5m.

[0135] This embodiment uses a sandy riverbed, with a stable slope i for scour craters taken as 1 / 3, and the most unfavorable scour in front of the dike is h=max( , =13.22m, the levee level is 2, △B is 10m, therefore, considering the safety margin and the safety distance B of the maximum impact area of ​​bridge and levee scour, B=49.66m.

[0136] Step 7: Determine whether the scouring of the bridge piers and the toe of the dike affects the safety of each other's foundations and whether integrated protection is required. The specific determination method is as follows: (1) When B≥B0 (the maximum influence range B of the scouring of the bridge piers and the toe of the dike is greater than or equal to the distance B0 between the bridge piers and the toe of the dike), the scouring caused by the two may have an adverse effect on the safety of each other, and integrated protection of the bridge and dike foundations is required; (2) When B<B0 (the maximum influence range B of the scouring of the bridge piers and the toe of the dike is less than the distance B0 between the bridge piers and the toe of the dike), it is considered that the scouring caused by the two does not affect the safety of each other, and integrated protection of the bridge and dike foundations is not required.

[0137] In the embodiment, the distance B0 between the bridge pier and the toe of the embankment is 40.72m, and B is 49.66m. Since B > B0, integrated protection against scour of the bridge and embankment foundation is required.

[0138] Step 8: Determine the protection range, i.e., determine the protection width B. W Heshun River protection length B L Planar protection width B W The length of the protective barrier along the bridge centerline, extending from the toe of the flood control dike into the river to the outer edge of the bridge pier (B), is given by equation 18. The length B along the river is... L Determined according to the dike grade, for a Class 1 dike project, B L Taking a 300m range upstream and downstream of the bridge, for a Class 2 levee, B L For other levels of levees, within a 150m range upstream and downstream of the bridge, B L Take a 50m range upstream and downstream of the bridge, such as Figure 1 .

[0139] B W =B0+b+B (Equation 18)

[0140] B = (h / i + △B) (Equation 19)

[0141] h=max( , (Equation 20)

[0142] In the embodiment, the width b of the bridge pier adjacent to the embankment is 3.2m, therefore, the protection width B W =B0+b+B=40.72+3.2+49.66=93.58m. The levee involved is of level 2. Therefore, the protection length BL along the river is taken as 150m above the bridge and 150m below the bridge.

[0143] Step 9: Determine the cross-sectional type of the integrated bridge-embankment foundation protection structure. This integrated bridge-embankment foundation protection structure is a riverbed protection measure adopted to eliminate the mutual influence of scouring between the adjacent bridge piers and the embankment toe. On the protection zone 4, starting from the water-facing toe protection platform of the embankment, it extends to point B outside the adjacent bridge pier 2, then slopes at a 1:1.5 to connect with the natural riverbed. The main method used is to protect the riverbed within the protection area determined in Step 8, using riprap or gabion cages. A 0.3m thick cushion layer is installed at the bottom of the riprap or gabion cages. The thickness of the riprap or gabion cages should not be less than 1.0m. If the riverbed in the protection zone is steep (outside the embankment toe platform and adjacent bridge piers), further measures will be taken. If the elevation difference is greater than or equal to 3m, a platform can be set up for every 3m elevation difference, and the platforms can be connected with a 1:1.5 slope to reduce the amount of engineering work in the protection zone; if the riverbed in the protection zone is relatively flat (outside the embankment toe platform and the bridge piers adjacent to the embankment). If the elevation difference is less than 4m, a uniform top elevation can be used for the protected area. See the protective cross-section type below. Figure 2 .

[0144] Step 10: Install isolation pile 5, which is the vibration isolation structure for pier 2 of the adjacent embankment. High-pressure jet grouting piles or precast pipe piles are used to install vibration isolation measures between pier 2 and the embankment. Conventional vibration isolation structures for piers involve arranging isolation piles 360° around the pier. While this method effectively eliminates or reduces the impact of pier vibration on the embankment, it is often labor-intensive, time-consuming, costly, and uneconomical. This invention proposes a "semi-enclosed" vibration isolation structure for pier vibration optimization based on the Ansys three-dimensional structural finite element numerical model. Its technical feature is that, based on the analysis and demonstration results of the Ansys three-dimensional structural finite element numerical model, high-pressure jet grouting piles or precast pipe piles are arranged 180° around the embankment side of the pier, forming a "semi-enclosed" structure. This achieves the beneficial effects of saving on vibration isolation measures, shortening the cycle, and reducing project investment without substantially changing the vibration isolation effect. Vibration isolation effects of different pier isolation ranges (embankment deformation cloud map) are shown below. Figure 3 Vibration isolation effect at different isolation depths (dike deformation cloud map) as follows Figure 4 .

[0145] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0146] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A design method of a bridge foundation integrated protection structure, characterized by: Includes the following steps: Step 1: Based on the river topography, hydrology, and design data of cross-river bridges and embankments, establish a two-dimensional hydrodynamic mathematical model of the river that includes cross-river bridges and embankments, and verify and calibrate the two-dimensional hydrodynamic mathematical model of the river using measured hydrological data; Step 2: Using a verified two-dimensional hydrodynamic mathematical model of the river, numerical simulation calculations of tidal dynamics are performed. For safety reasons, the model calculations do not consider tidal overflow. The tidal standard used in the calculation is the higher tidal defense standard between the dike project and the cross-river bridge project. Step 3: Based on the numerical simulation results of tidal dynamics in Step 2, analyze and extract the hydrological and hydraulic parameters near the bridge piers on the embankment; Step 4: Calculate the scour depth of the levee toe by using the scour formula ; Fifth step: calculate the scour depth of the bridge pier by using the scour depth calculation formula of the bridge pier ; consider the scour depth of the bridge pier from the perspective of engineering safety ; and consider the adverse superposition of the general scour depth and the local scour depth of the bridge pier, that is = + ; the required river channel characteristic parameters are determined according to the actual situation of the river channel where the project is located through surveying and mapping means, the bridge pier body size parameters are determined according to the bridge design data, and the hydrology and hydraulics parameters are calculated and obtained according to the bridge design data and the results of the tidal water dynamic numerical simulation calculation in the second step; Step 6: Determine the safety distance B considering a certain safety margin and the maximum impact area of bridge and embankment scour; take the maximum value of B in the following formulae as the most unfavorable scour depth and h The stable slope of the scour pit i According to the bed material composition of the river and engineering experience, the maximum impact range L of local scour after the embankment bridge pier is arranged h / i ; considering a certain safety margin ΔB, the safety distance B considering a certain safety margin and the maximum impact area of bridge and embankment scour can be determined, B = L + ΔB, ΔB is determined according to the grade of the embankment project, for a first-grade embankment, ΔB is taken as 20 m, for a second-grade and third-grade embankment, ΔB is taken as 10 m, and for a fourth-grade and fifth-grade embankment, ΔB is taken as 5 m;​ Step 7: Determine whether the scouring of the bridge piers and the toe of the dike has any impact on the safety of each other's foundations and whether integrated protection is required; the specific determination method is as follows: (1) When the maximum impact range of the scouring of the bridge piers and the toe of the dike is greater than or equal to the distance B0 between the bridge piers and the toe of the dike, the scouring caused by the two may have an adverse impact on the safety of each other, and integrated protection of the bridge and dike foundations is required; (2) When the maximum impact range of the scouring of the bridge piers and the toe of the dike is less than the distance B0 between the bridge piers and the toe of the dike, it is considered that the scouring caused by the two does not affect the safety of each other, and integrated protection of the bridge and dike foundations is not required. Step 8: Determine the protection range, i.e. determine the protection width B W and the protection length B along the river L ; the protection width B W is along the bridge center line, from the embankment toe to the outside of the bridge pier, see formula 18; the protection length B along the river L According to the embankment grade, for a first-class embankment project, B L Take the range of 300m upstream and downstream of the bridge, for a second-class embankment, B L Take the range of 150m upstream and downstream of the bridge, for other grades of embankment, B L Take the range of 50m upstream and downstream of the bridge; B W =B0+b+B (Equation 18); B = ( h / i + ΔB) (Equation 19); h =max( , (Equation 20); In the formula: B W B0 is the distance between the bridge pier and the embankment toe, in meters. b represents the width of the bridge pier adjacent to the embankment, in meters (m). B is the safety distance considering certain safety margin and the maximum influence area of bridge and embankment scour, unit: m; h is the adverse scour depth, unit: m; and are the embankment toe scour depth and the pier scour depth, respectively, unit: m.

2. The design method for an integrated protective structure for bridge embankment foundations according to claim 1, characterized in that: The scouring formula in the fourth step is formula 1 to formula 3, and the hydrology and hydraulics parameters required for calculation are obtained by using the calculation results of the tidal hydrodynamic numerical simulation in the second step, the bulk density of the sediment and the median particle size Determined according to the field sediment sampling and particle size test; (Formula 1); (Formula 2); (Formula 3); wherein: is the scour depth of the dike toe, m; is the water depth in front of the dike, m; is the average flow velocity of the nearshore vertical line, m / s; is the incipient velocity of the sediment, m / s; n is related to the shape of the dike protection bank slope in the plane, taken n = 1 / 4 ~ 1 / 6; is the maximum flow velocity in front of the dike, m / s; is the median particle size of the riverbed sediment, m; , are the bulk densities of the sediment and water, respectively, KN / m³; is the flow non-uniformity coefficient.

3. The design method for an integrated protective structure for bridge embankment foundations according to claim 1, characterized in that: in the fifth step h n and h b According to the calculation of the spur dike pier scouring formula 4~17, (1) General scour depth at bridge piers Calculation (Formula 4); (Formula 5); (Formula 6); In the formula: —The maximum water depth (m) under the bridge after typical scouring; —Design flow rate (m³ / s); —The design flow rate (m³ / s) passing through the riverbed under the bridge is taken as Qp when the riverbed can be expanded to cover the entire bridge; —Design flow rate (m³ / s) of the river channel under natural conditions; —Design flow rate of the riverbed under the bridge under natural conditions (m³ / s); —Width of the river channel in its natural state (m); — Width of the river channel (m) within the bridge length range; when the river channel can be widened to the full length of the bridge, the total length of the bridge span shall be used. —Channel width (m) under the bed-forming flow rate, which is the channel width at the flat beach water level for a complex riverbed; λ — At the design water level, Within the width range, the ratio of the total water-blocking area of ​​the bridge piers adjacent to the embankment to the water-passing area; μ——Lateral compressibility coefficient of water flow near bridge piers; —Maximum water depth in the riverbed; —Unit width flow concentration coefficient, changes in the piedmont area, wandering, and wide-shoal river sections When >1.8, The value is 1.8; —The average water depth of the channel under the bed-forming flow rate (m), which is the average water depth of the channel when the flat beach water level is taken for a complex riverbed; Revised official (Equation 7); In the formula: —The net width of the bridge openings in the riverbed (m) is the net width of the bridge openings when the riverbed under the bridge can be expanded to the full bridge. —Average water depth in the riverbed under the bridge (m); —Average particle size of riverbed sediment (mm); —A coefficient related to sediment content during the flood season; The scour depth of bridge piers near embankments is generally calculated according to Formula 8; = - (Equation 8); In the formula: — Typical scour depth (m) of bridge piers near embankments; —The maximum water depth (m) under the bridge after typical scouring; —Water depth under the bridge before scouring (m); (2) Local scour depth calculate When the bottom surface of the pier cap is lower than the general scour curve, it should be calculated as the superstructure; when the bottom surface of the pier cap is higher than the water surface, it should be calculated as a frame pier; the relative height of the pier cap bottom surface... At that time, local scour depth Calculate according to formula 9: (Equation 9); (Equation 10); (Equation 11); (Equation 12); (Equation 13); (Equation 14); (Equation 15); When using simplified calculations for general scouring: (Equation 16); When using modified calculations for general scouring: (Equation 17); In the formula: —Local scour depth (m); —Relative height of the bottom surface of the foundation; —The shape coefficient of a single pile is determined according to the numbering of piers 1, 2, 3, and 5; —Pile group coefficient; —Reduction factor for submerged columns; φ —Pile diameter (m); —Calculated width of bridge piers near the embankment; —Pier type coefficient; —Pier cap reduction coefficient; —Influence coefficient of riverbed particles; —The general scouring velocity of the flow before the pier is 0.1 to 6 m / s; —Initial flow velocity of sediment in the riverbed (m / s); —Initial flow velocity of sediment in front of the pier (m / s); --index; —Average particle size of riverbed sediment (mm); —The maximum water depth (m) under the bridge after typical scouring; —The width of the pile group distributed perpendicular to the direction of water flow; —The number of rows of piles; —Average flow velocity in the river channel (m / s); —Average water depth of the river channel (m).

4. The design method for an integrated protective structure for bridge embankment foundations according to claim 1, characterized in that: In the sixth step, the erosion stabilization slope ratio i The scour stability slope is determined based on the riverbed composition and engineering experience, for pebble riverbeds. i Take 1 / 2; for sandy riverbeds, the stable slope of the scour gully is... i Take 1 / 3.

5. The integrated bridge and embankment foundation protection structure in the design method of an integrated bridge and embankment foundation protection structure according to any one of claims 1-4, characterized in that: The system includes a bridge across the river (1) and a dike (3) placed on the riverbank. The bridge across the river (1) has piers (2) on both sides of the dike within the protection range. Isolation piles (5) are installed at the piers (2) on both sides of the dike (3). A protection zone (4) is set outside the dike (3). The protection zone (4) is located outside the dike (3) and extends from the dike toe to the piers (2) on both sides of the dike. The protection zone (4) includes a cushion layer laid on the riverbed and connected to the dike (3). The cushion layer is 0.3m-0.5m thick. The protection zone (4) also includes gabion cages laid on the cushion layer. The gabion cages are at least 1.0m thick. The protection zone is determined comprehensively based on the local scour depth of the dike toe, the scour depth of the piers, and the dike grade.

6. The integrated bridge embankment foundation protection structure according to claim 5, characterized in that: When the height difference between the protected areas is greater than or equal to 4m, a platform shall be set up for every 2-3m height difference; the platforms shall be connected with a slope of 1:1.

5.

7. The integrated protection structure for bridge embankment foundations according to claim 5, characterized in that: The isolation pile (5) is a semi-enclosed structure. High-pressure jet grouting piles or precast pipe piles are used to arrange the isolation piles at 180° on the embankment side of the bridge pier (2) adjacent to the embankment.

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