A method and system for simulating the movement dynamics of a debris flow

Abstract

The present application relates to a kind of debris flow movement dynamics simulation method and system, wherein the method comprises: determining debris flow movement dynamics control equation according to the flow rate of debris flow fluid;Debris flow movement dynamics control equation includes continuity equation and momentum equation;Debris flow fluid density is obtained according to debris flow movement dynamics control equation;The amount of suspended sediment of suspended sediment and the single-width sediment transport rate of bed surface layer sediment are determined according to the density of debris flow fluid;The thickness of moving load layer is determined using the thickness calculation formula of moving load layer;The shape of the bottom of debris flow gully is calculated using the amount of suspended sediment of suspended sediment, the single-width sediment transport rate of bed surface layer sediment and the thickness of moving load layer thereof.The present application obtains the amount of suspended sediment of suspended sediment, the single-width sediment transport rate of bed surface layer sediment and the thickness of moving load layer thereof based on debris flow movement dynamics control equation, and based on this, the shape of the bottom of debris flow gully can be more accurately calculated, which provides a basis for the design of foundation depth of prevention and control engineering.

Description

Technical Field

[0001] This invention relates to the field of natural disaster early warning technology, and in particular to a method and system for simulating the dynamics of debris flow. Background Technology

[0002] Large-scale debris flows in steep mountain slopes are inevitable during extreme rainfall. The evolution of debris flow channels is extremely complex, especially in the narrow, steep sections of the upper and middle reaches of the basin. After heavy rainfall, the watershed rapidly converges into the steep river channel, resulting in a turbulent or fluctuating flow field with significant momentum, energy, and diffusion capacity. The water body influences the flow field through impact, scouring, and stirring. In the lower reaches of the basin, which are generally gentle depositional areas, if a "fire hose" effect exists in the upper and middle reaches of the channel, the enormous inertial impact force of the water body causes the loose solid material in that section to disintegrate and eventually be engulfed in the fluid, forming debris flow slurry. Simultaneously, it rapidly and deeply cuts deep channels in the alluvial fan deposits, forming narrow and straight channels with significantly increased longitudinal slopes and drastic changes in fluid flow, greatly increasing the destructive power of the debris flow.

[0003] Debris flows in steep mountain slopes differ significantly from traditional debris flows in their formation mechanisms, destructive modes, and even management concepts. While recent theoretical studies have addressed the erosion energy conditions of debris flows on gully soil in steep mountain slopes, they lack analysis of mechanical mechanisms. This makes it difficult to quantitatively describe the development of erosion processes, such as changes in erosion rate, or to predict physical processes like erosion depth or scour evolution mechanisms. Therefore, relying solely on such studies to guide the management of debris flow gullies is far from sufficient. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a method and system for simulating the dynamics of debris flow.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A method for simulating the dynamics of debris flow includes:

[0007] The dynamic control equations for debris flow motion are determined based on the flow velocity of the debris flow; the dynamic control equations for debris flow motion include a continuity equation and a momentum equation.

[0008] The density of the debris flow fluid is obtained based on the dynamic control equation of the debris flow motion.

[0009] The amount of suspended sediment and the unit width transport rate of sediment on the surface of the bed are determined based on the density of the sediment fluid.

[0010] The thickness of the bedload layer was determined using the formula for calculating bedload layer thickness.

[0011] The shape of the bottom of the debris flow gully bed is calculated using the amount of suspended sediment, the unit width transport rate of sediment on the bed surface, and the thickness of the bedload layer.

[0012] Preferably, the continuity equation is:

[0013]

[0014] Among them, V F R represents the volume fraction of the fluid flow, t represents time, ρ is the fluid density, and R is the fluid density. DIF For the turbulent diffusion term, R sOR Let A be the mass source term, where u, v, and w are the velocity components in the x, y, and z coordinate directions, respectively. x A y A z Let R and ξ represent the projected areas of the fluid in the x, y, and z directions, respectively, and let R and ξ be coefficients related to the choice of the coordinate system.

[0015] Preferably, the momentum equation is:

[0016]

[0017]

[0018]

[0019] In the formula: G x G y G z f is the acceleration due to gravity in the fluid. x f y f z b is viscous acceleration; x b y b z The energy loss of the fluid passing through the pores of the source body; A is the cross-sectional area of ​​the fluid; u w u s These are the velocity components of water and solid particles in the x-direction, respectively; v w and v s δ represents the velocity components of water and solid particles in the y-direction, respectively; δ represents the thickness of the bedload layer.

[0020] Preferably, the formula for calculating the amount of suspended sediment is:

[0021]

[0022] Among them, u lift This is used to calculate the amount of sediment that transforms from bottom sediment to suspended sediment; α is the entrainment coefficient; n sd* represents the outward normal direction of the sand bed surface; d* represents the dimensionless particle size of the sediment particles; θ represents the Shield number of the bed surface; θ cr d is the critical Shields number; g is the acceleration due to gravity; d s ρ is the diameter of the sediment particles; s This refers to the density of the sediment.

[0023] Preferably, the unit width sediment transport rate of the surface sediment layer is:

[0024]

[0025] Where, q b Φ represents the unit width transport rate of sediment on the bed surface, Φ represents the bedload transport intensity, and d represents the sediment particle size.

[0026] Preferably, the formula for calculating the thickness of the bedrock is:

[0027]

[0028] Where δ represents the thickness of the bedrock, θ i Let represent the Shield number of the i-th bed surface unit.

[0029] The present invention also provides a debris flow motion dynamics simulation system, comprising:

[0030] A debris flow motion dynamic control equation construction module is used to determine the debris flow motion dynamic control equation based on the flow velocity of the debris flow; the debris flow motion dynamic control equation includes a continuity equation and a momentum equation.

[0031] The debris flow density calculation module is used to obtain the debris flow density based on the debris flow dynamic control equation.

[0032] The mudstone fluid density analysis module is used to determine the amount of suspended sediment and the unit width transport rate of sediment on the surface of the bed based on the mudstone fluid density.

[0033] The bedrock thickness calculation module is used to determine the bedrock thickness using the bedrock thickness calculation formula;

[0034] The shape calculation module at the bottom of the gully bed is used to calculate the shape of the bottom of the debris flow gully bed using the amount of suspended sediment, the unit width transport rate of sediment on the surface of the bed, and the thickness of the bedload layer.

[0035] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps in the above-described debris flow motion dynamics simulation method.

[0036] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0037] The beneficial effects of the debris flow motion dynamic simulation method and system provided by the present invention are as follows: Compared with the prior art, the present invention obtains the amount of suspended sediment, the unit width transport rate of sediment on the surface of the bed, and the thickness of the bedload layer based on the debris flow motion dynamic control equation, and based on this, it can more accurately calculate the shape of the bottom of the debris flow gully, providing a basis for the design of the foundation burial depth of the prevention and control project. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in 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.

[0039] Figure 1 A flowchart of a debris flow motion dynamics simulation method provided in an embodiment of the present invention. Detailed Implementation

[0040] 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.

[0041] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Please see Figure 1 A method for simulating the dynamics of debris flow, comprising:

[0043] Step 1: Determine the dynamic control equations for debris flow based on the flow velocity of the debris flow; the dynamic control equations for debris flow include the continuity equation and the momentum equation.

[0044] The continuity equation in this embodiment of the invention is:

[0045]

[0046] Among them, V F R represents the volume fraction of the fluid flow, t represents time, ρ is the fluid density, and R is the fluid density. DIF For the turbulent diffusion term, R sOR Let A be the mass source term, where u, v, and w are the velocity components in the x, y, and z coordinate directions, respectively. x Ay A z Let R and ξ represent the projected areas of the fluid in the x, y, and z directions, respectively, and let R and ξ be coefficients related to the choice of the coordinate system.

[0047] The momentum equation in this embodiment of the invention is:

[0048]

[0049]

[0050]

[0051] In the formula: G x G y G z f is the acceleration due to gravity in the fluid. x f y f z b is viscous acceleration; x b y b z The energy loss of the fluid passing through the pores of the source body; A is the cross-sectional area of ​​the fluid; u w u s These are the velocity components of water and solid particles in the x-direction, respectively; v w and v s δ represents the velocity components of water and solid particles in the y-direction, respectively; δ represents the thickness of the bedload layer.

[0052] Step 2: Obtain the debris flow density based on the aforementioned debris flow dynamic control equation;

[0053] Step 3: Determine the amount of suspended sediment and the unit width transport rate of the surface sediment based on the density of the sediment fluid.

[0054] In the initial stage of debris flow erosion, sediment exists in water in two states: suspended sediment and bedload. Since the hydrodynamics around individual sediment particles and the boundary layer at the interface are difficult to calculate, an empirical model is used. Furthermore, the formula for calculating the suspended sediment volume in this embodiment of the invention is as follows:

[0055]

[0056] Among them, u lift This is used to calculate the amount of sediment that transforms from bottom sediment to suspended sediment; α is the entrainment coefficient; n s d* represents the outward normal direction of the sand bed surface; d* represents the dimensionless particle size of the sediment particles; θ represents the Shield number of the bed surface; θ cr d is the critical Shields number; g is the acceleration due to gravity; d s ρ is the diameter of the sediment particles; s This refers to the density of the sediment.

[0057] The rolling or jumping of sediment particles on the surface of the trench bed is a fundamental form of material transport. The VanRijn unit width sediment transport rate is used to calculate the unit width sediment transport rate of the surface layer. Specifically, the unit width sediment transport rate of the surface layer in this embodiment is:

[0058]

[0059] Where, q b Φ represents the unit width transport rate of sediment on the bed surface, Φ represents the bedload transport intensity, and d represents the sediment particle size.

[0060] Step 4: Determine the thickness of the bedload layer using the formula for calculating bedload layer thickness; the formula for calculating bedload layer thickness is:

[0061]

[0062] Where δ represents the thickness of the bedrock, θ i Let represent the Shield number of the i-th bed surface unit.

[0063] Step 5: Calculate the shape of the bottom of the debris flow gully bed using the amount of suspended sediment, the unit width transport rate of the surface sediment, and the thickness of the bedload layer.

[0064] In practical applications, this invention, based on FAVOR technology, uses the solid volume fraction within each grid to determine the surface of the solids. This allows for the definition of independent, complex geometries within a structured grid, fully utilizing simple rectangular grids to represent arbitrarily complex geometric shapes. In the fluid region, the sediment concentration in each grid is calculated using model formulas; when the sediment concentration exceeds the maximum concentration, sedimentation occurs. The sediment transport model employs FAVOR technology, accurately describing the shape of the gully bed bottom by using the area and volume fraction parameters of sediment deposited in each grid within the sediment region calculated throughout the scouring process.

[0065] The present invention also provides a debris flow motion dynamics simulation system, comprising:

[0066] A debris flow motion dynamic control equation construction module is used to determine the debris flow motion dynamic control equation based on the flow velocity of the debris flow; the debris flow motion dynamic control equation includes a continuity equation and a momentum equation.

[0067] The debris flow density calculation module is used to obtain the debris flow density based on the debris flow dynamic control equation.

[0068] The mudstone fluid density analysis module is used to determine the amount of suspended sediment and the unit width transport rate of sediment on the surface of the bed based on the mudstone fluid density.

[0069] The bedrock thickness calculation module is used to determine the bedrock thickness using the bedrock thickness calculation formula;

[0070] The shape calculation module at the bottom of the gully bed is used to calculate the shape of the bottom of the debris flow gully bed using the amount of suspended sediment, the unit width transport rate of sediment on the surface of the bed, and the thickness of the bedload layer.

[0071] This invention obtains the amount of suspended sediment, the unit width transport rate of sediment on the surface of the bed, and the thickness of the bedload layer based on the dynamic control equation of debris flow movement. Based on this, the shape of the bottom of the debris flow gully can be calculated more accurately, providing a basis for the design of the foundation burial depth of the prevention and control project.

[0072] The present invention also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it implements the steps in the above-described debris flow motion dynamics simulation method. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided by the present invention are the same as the beneficial effects of the debris flow motion dynamics simulation method described in the above-described technical solution, and will not be repeated here.

[0073] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0074] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for simulating the dynamics of debris flow, characterized in that, include: The dynamic control equations for debris flow motion are determined based on the flow velocity of the debris flow; the dynamic control equations for debris flow motion include the continuity equation and the momentum equation. The density of the debris flow fluid is obtained based on the dynamic control equation of the debris flow motion. The amount of suspended sediment and the unit width transport rate of sediment on the surface of the bed are determined based on the density of the sediment fluid. The thickness of the bedload layer was determined using the formula for calculating bedload layer thickness. The shape of the bottom of the debris flow gully bed is calculated using the amount of suspended sediment, the unit width transport rate of sediment on the bed surface, and the thickness of the bedload layer. The continuity equation is: Among them, V F R represents the volume fraction of the fluid flow, t represents time, ρ is the fluid density, and R is the fluid density. DIF For the turbulent diffusion term, R sOR Let A be the mass source term, where u, v, and w are the velocity components in the x, y, and z coordinate directions, respectively. x A y A z Let R and Z represent the projected areas of the fluid in the x, y, and z directions, respectively. These are coefficients related to the choice of coordinate system; The momentum equation is: In the formula: G x G y G z f is the acceleration due to gravity in the fluid. x f y f z b is viscous acceleration; x b y b z The energy loss of the fluid passing through the pores of the source body; A is the cross-sectional area of ​​the fluid; u w , These are the velocity components of water and solid particles in the x-direction, respectively. and , respectively, represent the velocity components of water and solid particles in the y-direction; δ represents the thickness of the bedload layer; The formula for calculating the amount of suspended sediment is as follows: in, This is used to calculate the amount of sediment that transforms from bottom sediment to suspended sediment; α is the entrainment coefficient; n s d* represents the outward normal direction of the sand bed surface; d* represents the dimensionless particle size of the sediment particles; θ represents the Shield number of the bed surface; θ cr The critical Shields number; d is the acceleration due to gravity; s The diameter of the sediment particles; The density of the sediment; The unit width sediment transport rate of the surface sediment in the bed is: in, This represents the sediment transport rate per unit width of the surface sediment layer. The value represents the bedload transport intensity, and d represents the sediment particle size. The formula for calculating the thickness of the transported mass layer is as follows: in, Indicates the thickness of the bedrock. .

2. A debris flow motion dynamics simulation system, characterized in that, For implementing the debris flow dynamics simulation method as described in claim 1, the debris flow dynamics simulation system comprises: A debris flow motion dynamic control equation construction module is used to determine the debris flow motion dynamic control equation based on the flow velocity of the debris flow; the debris flow motion dynamic control equation includes a continuity equation and a momentum equation. The debris flow density calculation module is used to obtain the debris flow density based on the debris flow dynamic control equation. The mudstone fluid density analysis module is used to determine the amount of suspended sediment and the unit width transport rate of sediment on the surface of the bed based on the mudstone fluid density. The bedrock thickness calculation module is used to determine the bedrock thickness using the bedrock thickness calculation formula; The shape calculation module at the bottom of the gully bed is used to calculate the shape of the bottom of the debris flow gully bed using the amount of suspended sediment, the unit width transport rate of sediment on the surface of the bed, and the thickness of the bedload layer.

3. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps in the debris flow motion dynamics simulation method as described in claim 1.

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