Bank collapse prediction method and system considering rapid water recession rate of river channel

Abstract

The invention discloses a bank collapse prediction method and system considering the rapid water recession rate of a riverway, and belongs to the technical field of river power, and the method comprises the steps: obtaining the basic data of the riverway and a river bank, specifically including the soil parameter value of the riverway, the topographic data of the riverway, the hydrological data and the geometric dimension of the section of the river bank; a stability calculation module in the river bank stability model is improved, specifically, seepage force J at the water recession rate is introduced when the river bank stability Fs is calculated, basic data of a river channel and a river bank are input into the improved river bank stability model, the river bank stability is predicted, when the river bank stability Fs is larger than or equal to 1, the river bank is stable, and if not, bank collapse occurs. The method considers the influence of the seepage force on the stability of the river bank at the rapid water recession rate of the river, and can accurately predict the stability of the river bank.

Description

Technical Field

[0001] The present invention belongs to the technical field of river dynamics, and specifically relates to a bank collapse prediction method and system considering the rapid river water recession rate. Background Art

[0002] The phenomenon of riverbank collapse is widely distributed in major rivers around the world and is a natural disaster with great harm. Taking the middle and lower reaches of the Yangtze River as an example, the middle and lower reaches of the Yangtze River have an important strategic position in the economic and social development of our country. In the past more than 70 years, the cumulative length of riverbank collapse in the middle and lower reaches is about 1800 km (accounting for 45% of the total riverbank length), and the average annual riverbank collapse is about 25 km. Especially during the water recession period, an excessive river water recession rate is not conducive to the stability of the riverbank. When the river water level drops rapidly, the water inside the riverbank slope cannot be drained in time, resulting in a relatively high level of pore water pressure inside, while the external water level drops rapidly. In this case, the pressure difference between the inside and outside of the riverbank soil increases, forming an outward seepage force. However, due to the numerous influencing factors of bank collapse failure, the existing bank collapse research has not considered the influence of seepage force on riverbank stability under the rapid river water recession rate, so there is no mature calculation and prediction method in this regard.

[0003] To solve this problem, the present invention proposes a bank collapse prediction method considering the rapid river water recession rate, which can provide technical support for the comprehensive management and protection of rivers. Summary of the Invention

[0004] Aiming at the deficiencies in the prior art, the present invention provides a bank collapse prediction method and system considering the rapid river water recession rate, which considers the influence of seepage force on riverbank stability under the rapid river water recession rate and can accurately predict the stability of the riverbank.

[0005] The present invention provides the following technical solutions:

[0006] In the first aspect, a bank collapse prediction method considering the rapid river water recession rate is provided, including:

[0007] Obtain the basic data of the river and the riverbank, specifically including: the soil parameter values of the river, the river terrain data, the hydrological data, and the geometric dimensions of the riverbank cross-section;

[0008] Improve the stability calculation module in the riverbank stability model. Specifically, when calculating the riverbank stability F s introduce the seepage force J under the water recession rate. The riverbank stability F s is:

[0009]

[0010] where c′ is the effective cohesion of the soil, L is the length of the collapse failure surface in the soil, W is the weight of the soil, P is the hydrostatic pressure exerted on the soil by the external water flow, μa is the pore water pressure of the soil mass, β is the angle of the collapse surface, and is the effective internal friction angle of the soil mass;

[0011] Input the basic data of the river channel and the river bank into the improved river bank stability model to predict the river bank stability. When the river bank stability F s ≥1, the river bank is stable; otherwise, bank collapse occurs.

[0012] Optionally, the soil parameters include cohesion, internal friction angle, saturated unit weight and natural unit weight of the soil mass; the hydrological data includes scouring coefficient, hydraulic radius and hydraulic gradient of the water body; the river channel topographic data includes river channel water depth and height of the phreatic line of the river channel; the geometric dimensions of the river bank section include: river bank height, river bank width, slope of the slip surface, cross-sectional shape and radius of curvature.

[0013] Optionally, when calculating the river bank stability F s , the influence of the seepage force J under the falling water rate on the river bank is represented by the reaction force of the pore water weight contained in the height between the phreatic line of the river bank soil mass and the river channel water level plus the buoyancy force on the soil mass, specifically as follows:

[0014]

[0015] where γ w is the unit weight of water, h2 is the height between the phreatic line and the river bank water level, and h4 is the scouring height at the toe of the slope.

[0016] Optionally, the calculation formula of the river bank stability F a is specified by using the pore water pressure μ of the soil mass, the soil weight W, the hydrostatic pressure P exerted on the soil mass by the external water flow, and the seepage force J, and the calculation formula of the specified river bank stability F s is obtained: s

[0017]

[0018] where γ is the natural unit weight of the soil mass, γ′ is the buoyant unit weight of the soil mass, h1 is the height above the phreatic line, and h3 is the height below the river bank water level.

[0019] Optionally, the length L of the collapse failure surface in the soil mass is obtained according to the geometric relationship between the river bank height and the crack depth at the top of the river bank;

[0020]

[0021] where h t is the crack depth at the top of the river bank.

[0022] ​Optionally, the improved riverbank stability model further includes a water flow scouring module. The water flow scouring module calculates the lateral scouring width of the riverbank according to the riverbank scouring time, and imports the new terrain after scouring into the riverbank stability module for calculating the riverbank stability.

[0023] The water flow scouring module calculates the lateral scouring width E of the riverbank according to the riverbank scouring time, specifically as follows:

[0024] E = k·(τ0 - τ c ) α ·Δt

[0025] where k is the scouring coefficient; α is the scouring index, generally taken as 1.0; τ0 is the water flow shear stress, and τ c is the incipient shear stress of the riverbank soil mass; Δt is the set scouring time.

[0026] Optionally, the riverbank stability model is the BSTEM model, the Osman riverbank stability model or the Darby model.

[0027] In a second aspect, a bank collapse prediction system considering the rapid water recession rate of the river channel is provided, including:

[0028] A data collection module for obtaining the basic data of the river channel and the riverbank, specifically including: the soil parameter values of the river channel, the river channel terrain data, the hydrological data, and the geometric dimensions of the riverbank cross-section;

[0029] A model construction module for improving the stability calculation module in the riverbank stability model. Specifically, when calculating the riverbank stability F s the seepage force J under the water recession rate is introduced. The riverbank stability F s is:

[0030]

[0031] where c′ is the effective cohesion of the soil mass, L is the length of the collapse failure surface in the soil mass, W is the weight of the soil mass, P is the hydrostatic pressure applied to the soil mass by the external water flow, μ a is the pore water pressure of the soil mass, β is the angle of the collapse surface, and is the effective internal friction angle of the soil mass;

[0032] A bank collapse prediction module for inputting the basic data of the river channel and the riverbank into the improved riverbank stability model to predict the riverbank stability. When the riverbank stability F s ≥1, the riverbank is stable; otherwise, a bank collapse occurs.

[0033] In a third aspect, a computer device is provided, including a processor and a memory; wherein, when the processor executes the computer program stored in the memory, the steps of the bank collapse prediction method considering the rapid water recession rate of the river channel according to any one of the first aspect are implemented.

[0034] In a fourth aspect, a computer-readable storage medium is provided for storing a computer program; when the computer program is executed by a processor, the steps of the bank collapse prediction method considering the rapid water recession rate of the river channel according to any one of the first aspect are implemented.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] The present invention considers the influence of seepage force on the stability of riverbanks under the rapid water recession rate of the river channel, introduces the seepage force under the water recession rate when calculating the stability of riverbanks, and the seepage force is represented by the reaction force of the pore water weight contained in the height between the phreatic line of the riverbank soil and the river water level plus the buoyancy force on the soil, clarifying the reason for the increased probability of bank collapse during the water recession period. The bank collapse prediction method considering the rapid water recession rate of the river channel of the present invention has higher prediction accuracy compared with the conventional method and can provide strong technical support for the comprehensive management and protection of river channels. Description of the Drawings

[0037] Figure 1 is a flowchart of the steps of a bank collapse prediction method considering the rapid water recession rate of the river channel according to the present invention;

[0038] Figure 2 is a schematic diagram of the generalization of the riverbank morphology given by the present invention. Detailed Embodiments

[0039] The present invention will be further described below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be used to limit the protection scope of the present invention. It should be noted that the term "including" and any deformation thereof in the specification and claims of the present invention and the above drawings are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0040] Embodiment 1

[0041] As Figure 1 and Figure 2 shown, a bank collapse prediction method considering the rapid water recession rate of the river channel is provided, including the following steps:

[0042] S1: Obtain the basic data of the river channel and the river bank, specifically including: the soil parameter values of the river channel, the river channel terrain data, the hydrological data, and the geometric dimensions of the river bank cross-section.

[0043] Specifically, the soil parameter values include cohesion, internal friction angle, saturated unit weight and natural unit weight of the soil; the hydrological data includes the scour coefficient, hydraulic radius and hydraulic gradient of the water body; the river channel terrain data includes the river channel water depth and the height of the river channel phreatic line; the geometric dimensions of the river bank cross-section include: river bank height, river bank width, sliding surface slope, cross-section shape and radius of curvature.

[0044] The soil parameter values and the geometric dimensions of the river bank cross-section are obtained according to the measured river bank terrain data.

[0045] S2: Improve the stability calculation module in the river bank stability model. Specifically, when calculating the river bank stability F s introduce the seepage force J under the recession rate.

[0046] The river bank stability model is the BSTEM model, the Osman river bank stability model or the Darby model, and specific references can be made to the prior art.

[0047] The river bank stability model generally includes a water flow scour module and a stability calculation module.

[0048] S21: The water flow scour module calculates the lateral scour width of the river bank according to the river bank scour time, and imports the new terrain after scour into the stability calculation module for calculating the river bank stability.

[0049] The scour of the water flow on the toe of the river bank causes the deformation of the river bank slope, resulting in the occurrence of river bank collapse. The lateral scour of the water flow uses the residual shear stress method to calculate the deformation of the river bank under the condition of river channel water flow scour. The lateral scour of the water flow is mainly determined by the water flow scour intensity and the soil erosion resistance. The water flow scour module calculates the lateral scour width E of the river bank, specifically as follows:

[0050] E = k·(τ0 - τ c ) ɑ ·Δt

[0051] where k is the scour coefficient (m 3 / (N·s)); α is the scour index, which is related to the characteristics of the soil itself, and is generally taken as 1.0; τ0 is the water flow shear stress (N / m 2 ), τ c is the incipient shear stress of the river bank soil (N / m 2 ); Δt is the set scour time (s).

[0052] τ0 = γ ω RS

[0053] where γω For the severe water body (9.8 kN / m 3 ); R is the hydraulic radius (m), representing the ratio of the sub-region area to the wetted perimeter; S is the hydraulic gradient, which can be obtained based on the measured terrain.

[0054] The incipient shear stress τ of the riverbank soil c is generally obtained through soil erosion tests or calculated according to the particle size using empirical formulas.

[0055] S22: The stability calculation module calculates the riverbank stability F s .

[0056] Specifically, based on the mechanical model diagram of the riverbank force analysis under the rapid drawdown rate and the river dynamics theory, on the basis of the conventional bank collapse calculation method, according to the Terzaghi effective stress principle, the stability calculation module calculates the riverbank stability F s The formula for is:

[0057]

[0058] Among them, c′ is the effective cohesion of the soil (kN / m 2 ), L is the length of the collapse failure surface in the soil (m), W is the weight of the soil (kN / m), P is the hydrostatic pressure applied to the soil by the external water flow (kN / m), μ a is the pore water pressure of the soil (kN / m 2 ), β is the collapse surface angle (°), is the effective internal friction angle of the soil (°).

[0059] When calculating the riverbank stability F s , the influence of the seepage force J under the drawdown rate on the riverbank is represented by the reaction force of the pore water weight contained in the height between the phreatic line of the riverbank soil and the river water level plus the buoyancy force on the soil;

[0060]

[0061] Using the soil pore water pressure μ a , the soil weight W, the hydrostatic pressure P applied to the soil by the external water flow, and the seepage force J to specify the calculation formula for the riverbank stability F s , and obtain the specific calculation formula for the riverbank stability F s The calculation formula:

[0062]

[0063] Among them, γ is the natural unit weight of the soil (kN / m 3), the natural unit weight of the soil mass can be obtained by measuring the undisturbed soil using the core cutter method. γ′ is the buoyant unit weight of the soil mass, which is obtained by subtracting the unit weight of water (γ w = 9.8 kN / m 3 ) from the saturated unit weight, i.e., γ′ = γ sat - γ w . h1 is the height above the phreatic line (m), which can be obtained by the observation instruments buried in the field or calculated by the seepage equation. h2 is the height between the phreatic line and the riverbank water level (m), and the riverbank water level can be obtained according to the measured water level collected. h3 is the height below the riverbank water level (m), which can be obtained according to the measured riverbank cross-section topography collected. h4 is the scouring height at the toe of the slope (m), which can be obtained according to the measured riverbank topography collected or calculated by the riverbed erosion and deposition deformation equation.

[0064] The length L of the collapse failure surface in the soil mass is obtained according to the geometric relationship between the riverbank height and the crack depth at the top of the riverbank;

[0065]

[0066]

[0067] where h t is the crack depth at the top of the riverbank.

[0068] That is, for the improved riverbank stability model, first calculate the riverbank scouring deformation within a certain time Δt, then use the riverbank lateral scouring width E as the initial calculation condition for the riverbank cross-section shape, and finally calculate the riverbank stability F at a certain moment according to the riverbank stability calculation formula F s considering the seepage force under the condition of rapid river water recession rate in the river channel. s .

[0069] For example, when the riverbank stability model is the BSTEM model, the improved BSTEM model includes the TEM (Toe Erosion Model) module and the BSM (Bank Stability Module) module. The TEM module calculates the riverbank scouring deformation, and the BSM module calculates the riverbank stability according to the riverbank stability calculation formula F s considering the seepage force under the condition of rapid river water recession rate in the river channel of this application.

[0070] S3: Input the basic data of the river channel and the riverbank into the improved riverbank stability model to predict the riverbank stability. When the riverbank stability F s ≥1, the riverbank is stable; otherwise, bank caving occurs.

[0071] If the riverbank is stable, bank caving will not occur. When F sWhen =1, the riverbank stability is in a critical state and needs to be closely monitored. If necessary, update Δt and continuously predict the situation of the riverbank. Of course, when F s <1, the riverbank is unstable, and at this time, the riverbank collapses. Update the new form after the collapse and enter the stability F calculation of the next time period according to actual needs. s Calculation.

[0072] Embodiment 2

[0073] A specific example of a bank collapse prediction method considering the rapid recession rate of the river channel is given, including:

[0074] (1) Collected relevant basic data such as river channel topography data, hydrological data (flow rate, water level, etc.), and physical and mechanical parameters of the riverbank soil under the rapid recession rate of the river channel.

[0075] (2) Calculate the lateral erosion pattern of the riverbank within a certain time Δt based on the measured riverbank topography data.

[0076] (3) Determine the relevant dimensions of the riverbank cross-section and the values of soil mechanics parameters based on the eroded riverbank cross-section shape: c' is 3.7 kN / m 2 ; is 25°; γ w is 9.8 kN / m 3 ; γ is 17 kN / m 3 ; γ sat is 20 kN / m 3 ; γ′ is 10.2 kN / m 3 ; h1 is 0.5 m; h2 is 3 m; h3 is 1 m; h4 is 0.5 m; β is 60°; L is 4.1 m.

[0077] (4) Based on the riverbank stability F formula considering the action of seepage force, calculate the riverbank stability coefficient considering the action of seepage as: s The formula is:

[0078]

[0079] (5) After calculation, F s <1, at this time, the riverbank is in an unstable state, that is, a bank collapse occurs in the river channel at this time.

[0080] Using the conventional calculation method (i.e., not considering the action of seepage force), the riverbank stability F s is 1.50, and at this time, no bank collapse will occur in the river channel; when considering the influence of seepage force additionally under the condition of river channel recession, the riverbank stability F obtained by using the calculation method of the present invention sIt is 0.94. At this time, bank collapse occurs in the river channel. Combining with the collected actual riverbank terrain data, the value of the riverbank stability obtained by prediction using the present application is consistent with the actual situation, thus clarifying the reason for the increased probability of bank collapse during the recession period. Therefore, the present invention has better prediction accuracy compared with the conventional method.

[0081] Embodiment 3

[0082] A bank collapse prediction system considering the rapid recession rate of the river channel includes:

[0083] A data collection module for obtaining the basic data of the river channel and the riverbank, specifically including: the soil parameter values of the river channel, the river channel terrain data, the hydrological data, and the geometric dimensions of the riverbank cross-section;

[0084] A model construction module for improving the stability calculation module in the riverbank stability model. Specifically, when calculating the riverbank stability F s the seepage force J under the recession rate is introduced. The riverbank stability F s is:

[0085]

[0086] where c′ is the effective cohesion of the soil, L is the length of the collapse failure surface in the soil, W is the weight of the soil, P is the hydrostatic pressure applied to the soil by the external water flow, μ a is the pore water pressure of the soil, β is the angle of the collapse surface, is the effective internal friction angle of the soil;

[0087] A bank collapse prediction module for inputting the basic data of the river channel and the riverbank into the improved riverbank stability model to predict the riverbank stability. When the riverbank stability F s ≥1, the riverbank is stable; otherwise, bank collapse occurs.

[0088] For a more specific process of the above method, reference can be made to the corresponding content disclosed in the foregoing embodiments, and details will not be elaborated herein.

[0089] Embodiment 4

[0090] The present invention provides a computer device including a processor and a memory; wherein, when the processor executes the computer program stored in the memory, the steps of the above bank collapse prediction method considering the rapid recession rate of the river channel are implemented.

[0091] For a more specific process of the above method, reference can be made to the corresponding content disclosed in the foregoing embodiments, and details will not be elaborated herein.

[0092] Embodiment 5

[0093] In another embodiment, the present invention provides a computer-readable storage medium for storing a computer program; when the computer program is executed by a processor, the steps of the above-mentioned bank collapse prediction method considering the rapid water recession rate of the river channel are implemented.

[0094] For a more specific process of the above method, reference may be made to the corresponding content disclosed in the foregoing embodiments, and details will not be repeated herein.

[0095] In this specification, the various embodiments are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts between the embodiments, reference may be made to each other. For the systems, devices, and storage media disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and reference may be made to the description of the method part for related parts.

[0096] Those skilled in the art can clearly understand that the technology in the embodiments of the present invention can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution in the embodiments of the present invention, in essence, or the part that contributes to the prior art can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of the present invention.

[0097] The above is only the preferred embodiment of the present invention. The protection scope of the present invention is not limited to the above embodiments. Any technical solution falling within the idea of the present invention belongs to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, several improvements and refinements made without departing from the principle of the present invention should be regarded as within the protection scope of the present invention.

Claims

1. A bank collapse prediction method considering the rapid water recession rate of a river channel, characterized in that, Including: Obtaining the basic data of the river channel and the river bank, specifically including: the soil parameter values of the river channel, the river channel topographic data, the hydrological data, and the geometric dimensions of the river bank cross-section; Improve the stability calculation module in the riverbank stability model. Specifically, when calculating the riverbank stability F s introduce the seepage force J under the recession rate. The riverbank stability F s is as follows: Among them, c ′ is the effective cohesion of the soil mass, L is the length of the collapse failure surface in the soil mass, W is the weight of the soil mass, P is the hydrostatic pressure exerted on the soil mass by the external water flow, μ a is the pore water pressure of the soil mass, β is the angle of the collapse surface, is the effective internal friction angle of the soil mass; Input the basic data of the river channel and the river bank into the improved river bank stability model to predict the river bank stability. When the river bank stability F s ≥ 1, the river bank is stable; otherwise, bank collapse occurs.

2. The bank collapse prediction method considering the rapid water recession rate of the river channel according to claim 1, wherein The soil parameter values include cohesion, internal friction angle, saturated unit weight and natural unit weight of the soil; the hydrological data includes scour coefficient, hydraulic radius and hydraulic gradient of the water body; the river channel topographic data includes river channel water depth and river channel phreatic line height; the geometric dimensions of the river bank cross-section include: river bank height, river bank width, sliding surface slope, cross-sectional shape and radius of curvature.

3. The bank collapse prediction method considering the rapid water recession rate of the river channel according to claim 1, characterized in that When calculating the bank stability F s When calculating the influence of the seepage force J under the recession rate on the river bank, it is expressed by the reaction force of the pore water weight contained in the height between the phreatic line of the river bank soil and the river water level plus the buoyancy force on the soil. Specifically, it is as follows: where γ w is the unit weight of water, h2 is the height between the phreatic line and the river bank water level, and h4 is the scour height at the toe of the slope.

4. The bank collapse prediction method considering the rapid water recession rate of the river channel according to claim 3, characterized in that Utilize the pore water pressure μ of the soil mass a , the weight W of the soil mass, the hydrostatic pressure P exerted on the soil mass by external water flow, and the seepage force J to specify the calculation formula for the riverbank stability F s , and obtain the calculation formula for the specified riverbank stability F s : Among them, γ is the natural unit weight of the soil mass, γ ′ is the buoyant unit weight of the soil mass, h1 is the height above the phreatic line, and h3 is the height below the river bank water level.

5. The bank collapse prediction method considering the rapid water recession rate of the river channel according to claim 4, wherein The length L of the collapse failure surface in the soil is obtained according to the geometric relationship between the river bank height and the crack depth at the top of the river bank; Among them, h t is the crack depth at the top of the riverbank.

6. The bank collapse prediction method considering the rapid water recession rate of the river channel according to claim 1, characterized in that The improved river bank stability model further includes a water flow scour module, which calculates the lateral scour width of the river bank according to the river bank scour time, and imports the new topography after scour into the stability calculation module for calculating the river bank stability; The water flow scour module calculates the lateral scour width E of the river bank according to the river bank scour time, specifically as follows: E = k·(τ0 - τ c ) α ·Δt where k is the scouring coefficient; α is the scouring exponent, generally taken as 1.0; τ0 is the water flow shear stress, and τ c is the incipient shear stress of the riverbank soil; Δt is the set scouring time.

7. The bank collapse prediction method considering the rapid water recession rate of the river channel according to claim 1, wherein The river bank stability model is the BSTEM model, the Osman river bank stability model or the Darby model.

8. A bank collapse prediction system considering the rapid water recession rate of a river channel, characterized in that, Including: A data collection module for obtaining the basic data of the river channel and the river bank, specifically including: the soil parameter values of the river channel, the river channel topographic data, the hydrological data, and the geometric dimensions of the river bank cross-section; The model construction module is used to improve the stability calculation module in the riverbank stability model. Specifically, when calculating the riverbank stability F s the seepage force J under the recession rate is introduced, and the riverbank stability F s is as follows: Among them, c ′ is the effective cohesive force of the soil mass, L is the length of the collapse failure surface in the soil mass, W is the weight of the soil mass, P is the hydrostatic pressure applied to the soil mass by the external water flow, μ a is the pore water pressure of the soil mass, β is the angle of the collapse surface, is the effective internal friction angle of the soil mass; The bank collapse prediction module is used to input the basic data of the river channel and the river bank into the improved river bank stability model to predict the river bank stability. When the river bank stability F s ≥1, the river bank is stable; otherwise, bank collapse occurs.

9. A computer device, characterized in that, Including a processor and a memory; wherein, when the processor executes the computer program stored in the memory, the steps of the bank collapse prediction method considering the rapid drawdown rate of the river channel according to any one of claims 1-7 are implemented.

10. A computer-readable storage medium, characterized in that, For storing a computer program; when the computer program is executed by the processor, the steps of the bank collapse prediction method considering the rapid drawdown rate of the river channel according to any one of claims 1-7 are implemented.

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