Numerical simulation method for flood routing disaster chain of river blocking by debris flow and dam burst by barricade

Abstract

The invention discloses a debris flow river-dam burst flood routing disaster chain numerical simulation method, which comprises the following steps of: acquiring data required by the numerical simulation method based on a continuous medium fluid mechanics model of a three-phase medium of coupling water, coarse particles and fine particles; according to the method, a continuous medium mechanics theory is combined, three-phase media of water, coarse particles and fine particles are coupled through a continuous medium fluid mechanics model, and numerical simulation of a debris flow river-dam burst flood routing disaster chain is realized by adopting a finite difference method. The application considers the sediment transport effect of the main river flow when the debris flow converges into the main river and the influence of the sediment transport process of the main river channel on the dam burst process and the burst flood evolution process, and can simulate whether the debris flow blocks the river, how the dam burst after the river is blocked and the burst flood evolution process at the same time; the complete coupling process of the physical process of the debris flow river-dam burst flood routing disaster chain is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of mountain disaster simulation, and in particular relates to a numerical simulation method for the disaster chain of debris flow blocking a river and a dam burst flood evolution. Background Art

[0002] Debris flow blocking the river to form dams, dam breaches and flood evolution is a typical mountain disaster chain, posing a huge threat to human life, property safety and the ecological environment. Accurately simulating the evolution of debris flow blocking the river to form dams, dam breaches and floods is of great significance for early warning, disaster prevention and mitigation, and risk management. In related technologies, the assessment methods for debris flow blocking the river are mainly divided into two categories: statistical empirical models based on disaster history data and models based on physical mechanisms. Compared with statistical empirical models based on disaster history data, models based on physical mechanisms can better describe the development process of debris flow blocking the river to form dams, dam breaches and flood evolution.

[0003] In recent years, with the in-depth study of the dynamic mechanism of debris flow, people have gradually realized that the relative ratio of debris flow and main river flow has an important influence on the process of debris flow blocking the river. The existing model based on physical mechanism - numerical simulation of debris flow blocking the river first simulates the debris flow, and then uses the dam break model to further simulate it. It does not realize the complete coupling process of the physical process, nor does it consider the influence of the sediment transport of the main river flow and the main river channel on the burst of the dam and the evolution of the burst flood when the debris flow merges into the main river, resulting in a large deviation between the simulation results and the actual situation. Summary of the invention

[0004] The purpose of the present invention is to provide a numerical simulation method for the disaster chain of debris flow blocking a river-dam burst flood evolution, so as to solve the problem that there is a large deviation between the current numerical simulation results of debris flow blocking a river and the actual situation.

[0005] The embodiment of the present application is implemented as follows: a numerical simulation method for the disaster chain of debris flow blocking a river and a dam breach flood comprises: based on a continuous medium fluid mechanics model of coupled water, coarse particles and fine particles three-phase medium, obtaining data required for the numerical simulation method, the data comprising at least one of terrain data, debris flow volume, debris flow starting position, debris flow particle grading, channel soil grading, main river flow, and main river channel roughness coefficient.

[0006] In some embodiments, the governing equation of the continuum fluid mechanics model is: ; ; ; In the formula, Depth of debris flow or flood, unit: ; , for debris flow or flood along the Single-width flow in a direction, unit: ; , for debris flow or flood along the Single-width flow in a direction, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; is the density of debris flow or flood burst, unit: ; is the volume concentration of water in a debris flow or flood, unit: dimensionless; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; is the density of particulate matter in debris flow or flood, unit: ; is the density of clean water, unit: ; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional bed resistance, unit: ; The elevation of the terrain required for numerical simulation, unit: ; , is the acceleration due to gravity, unit: ; is the total erosion rate of debris flow or flood, unit: ; The total deposition rate of particulate matter in debris flow or flood burst, unit: ; is time, unit: .

[0007] In some embodiments, the transport equations for water, fine particles, and coarse particles during debris flow or flood outburst are: ; ; ; In the formula, Depth of debris flow or flood, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; is the volume concentration of water in a debris flow or flood, unit: dimensionless; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; is the erosion rate in debris flow or flood, in units: ; It is the volume percentage of water in the channel during the erosion of the channel by debris flow or flood, unit: dimensionless; It is the volume percentage of fine particles in channel materials during debris flow or flood erosion, unit: dimensionless; It is the volume percentage of coarse particles in the channel material during debris flow or flood erosion, unit: dimensionless; is the deposition rate of fine particles in debris flow or flood, unit: ; is the deposition rate of coarse particles in debris flow or flood, in units: ; is the diffusion coefficient of fine particles in debris flow or flood, unit: ; is time, unit: .

[0008] In some embodiments, the evolution equation of the terrain is: ; In the formula, is the trench bed porosity, unit: dimensionless; is the elevation of the terrain, in units: ; is the total deposition rate of debris flow or flood outburst, in units: ; is the total erosion rate of debris flow or flood, unit: ; is the sediment transport rate per unit width along the x direction, unit: ; is the sediment transport rate per unit width along the y direction, unit: ; is time, unit: .

[0009] Furthermore, the diffusion coefficient of fine particles in the fine particle transport equation is The calculation formula is as follows: ; In the formula, is the diffusion coefficient of fine particles in debris flow or flood, unit: ; κ = 0.4 represents the von Karman constant, unit: dimensionless; is the friction velocity of the bed surface of debris flow or flood, unit: ; The total resistance of the bottom of debris flow or flood, unit: ; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional bed resistance, unit: ; is the density of debris flow or flood burst, unit: ; h is the depth of debris flow or flood, unit: .

[0010] Furthermore, in the governing equation, the debris flow or flood erosion rate The calculation method is: ; In the formula, is the total erosion rate of gully bed sediment by outburst floods, unit: ; is the total debris flow erosion rate, unit: ; Γ is the transition factor from outburst flood to debris flow, unit: dimensionless, representing the critical volume concentration of total sediment material that distinguishes outburst flood from debris flow, and the calculation formula is: ; Where α is the attenuation exponent, unit: dimensionless, value is 13.8; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; It is the critical total particulate matter concentration that separates outburst floods from debris flows. Unit: dimensionless, with a value of 0.18.

[0011] Furthermore, The total erosion rate of debris flow The calculation equation is: ; In the formula, The total resistance of the bottom of debris flow or flood, unit: ; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Directional flow velocity, unit: ; is the density of debris flow or flood burst, unit: ; Depth of debris flow or flood burst calculated, unit: ; It is the pore water pressure coefficient in the ditch bed material when debris flow erodes the ditch, unit: dimensionless; is the channel slope, unit: °; It is the friction angle of the granular material in the channel when the debris flow erodes the channel, unit: °; It is the cohesion of the granular material in the channel when the debris flow erodes the channel, unit: ; is the acceleration due to gravity, unit: .

[0012] Understandably, is the channel slope, unit: °, calculated from the terrain.

[0013] Furthermore, The total erosion rate of flood on gully bed sediment is The calculation method is ; In the formula, is the total erosion rate of ditch bed sediment by outburst flood, unit: ; is the total resistance of the flood bed, unit: ; For flood breach Directional bed resistance, unit: ; For flood breach Directional bed resistance, unit: ; It is the erosion resistance of the gully bed material during the outburst flood erosion process, unit: ; is the empirical coefficient of outburst flood erosion, unit: .

[0014] Understandably, for and The maximum value of two numbers.

[0015] It can be understood that since the mud and sand particles are fully mixed and have strong integrity during the movement of debris flows, the sedimentation of the mud and sand particles can be ignored, and only the sedimentation of fine and coarse sediment particles during the movement of the flood burst is considered.

[0016] Furthermore, the transport equations for fine and coarse particles are and The calculation method is: ; ; In the formula, is the deposition rate of fine particles in the outburst flood movement, unit: ; is the deposition rate of coarse particles in the outburst flood movement, unit: ; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; It is an empirical parameter, with a value of 2.0-5.0, unit: dimensionless; Γ is the transition factor from flood outburst to debris flow, unit: dimensionless; is the sedimentation rate of fine particles in the burst flood movement, unit: , the calculation formula is: ; In the formula, is the kinematic viscosity of clean water, unit: ; It is the representative particle size of fine particles in the process of flood burst, unit: ; The density of fine particles in debris flow or flood, unit: ; is the density of clean water, unit: ; is the acceleration due to gravity, unit: ; is the sedimentation rate of coarse particles in the outburst flood movement, unit: , the calculation formula is: ; In the formula, is the kinematic viscosity of clean water, unit: ; It is the representative particle size of coarse particles in the process of flood burst, unit: ; The density of coarse particles in debris flow or flood burst, unit: ; is the density of clean water, unit: ; is the acceleration due to gravity, unit: .

[0017] Further, Sediment transport rate of coarse particles per width along the x direction and the sediment transport rate of coarse particles per width along the y direction The calculation methods are: ; ; In the formula, Debris flow or flood Single-width flow in a direction, unit: ; Debris flow or flood Single-width flow in a direction, unit: ; is the sediment transport rate of coarse particles per width, unit: , the calculation formula is: ; In the formula, is the Froude number of the fluid, unit: dimensionless; Depth of debris flow or flood, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; is the dimensionless bed shear stress, i.e., Shields number; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional bed resistance, unit: ; The density of coarse particles in debris flow or flood, unit: ; is the density of clean water, unit: ; It is the representative particle size of coarse particles in the process of flood burst, unit: ; is the acceleration due to gravity, unit: ; is the critical Shields number, unit: dimensionless, calculated as ; In the formula, is the empirical coefficient, unit: dimensionless; is the channel slope, unit: °; It is the friction angle between the granular materials in the channel when the channel is eroded by burst flood, unit: °.

[0018] Further, and Medium debris flow or flood along the Directional bottom resistance and debris flow or flood along the Directional bottom resistance The calculation formula is: ; ; In the formula, is the density of debris flow or flood burst, unit: ; is the volume concentration of water in a debris flow or flood, unit: dimensionless; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; is the density of particulate matter in debris flow or flood, unit: ; is the density of clean water, unit: ; Roughness coefficient of the outburst flood during its movement, unit: ; Depth of debris flow or flood, unit: ; , for debris flow or flood along the Single-width flow in a direction, unit: ; , for debris flow or flood along the Single-width flow in a direction, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; Γ is the transition factor from flood outburst to debris flow, unit: dimensionless; and The liquid slurry of debris flow or flood burst is Direction and Directional bed resistance, unit: ; and The coarse particles of debris flow or flood are Direction and Directional bed resistance, unit: ; is the acceleration due to gravity, unit: .

[0019] Furthermore, the liquid slurry of debris flow or flood bursting Directional bottom resistance and Directional bottom resistance The calculation formulas are: ; ; In the formula, Depth of debris flow or flood, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; is the dynamic viscosity of clean water, unit: Pa·s; Represents the volume concentration of fine particles in liquid mud, unit: dimensionless; It is the maximum allowable volume concentration of fine-grained sediment in liquid mud, unit: dimensionless, calculated as: ; In the formula, and Represents the fine-grained sediment i The diameter and mass percentage of each particle size class, unit: dimensionless; S v0 is the critical volume concentration at which the fluid changes from a Newtonian fluid to a Bingham fluid. Unit: dimensionless. The calculation formula is: ; k 0 is a correction factor, unit: dimensionless, expression: .

[0020] Understandably, It is the maximum allowable volume concentration of fine-grained sediment in liquid mud. Unit: dimensionless. This parameter is usually related to the specific surface area of ​​the particles.

[0021] Furthermore, the coarse particles of debris flow or flood are carried along Directional bottom resistance and Directional bottom resistance The calculation formulas are: ; ; In the formula, The coarse particles in debris flow or flood are The resistance to motion in the direction, in units: ; The coarse particles in debris flow or flood are The resistance to motion in the direction, in units: ; is the density of debris flow or flood burst, unit: ; It is the density of liquid slurry composed of fine particles and water, unit: ; is the volume concentration of water in a debris flow or flood, unit: dimensionless; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; is the density of particulate matter in debris flow or flood, unit: ; is the density of clean water, unit: ; Debris flow or flood Single-width flow in a direction, unit: ; Debris flow or flood Single-width flow in a direction, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; Depth of debris flow or flood, unit: ; The bottom edge of a debris flow or flood Slope of direction, unit:°; The bottom edge of the debris flow Slope of direction, unit:°; is the friction angle between coarse particles and the bottom bed in debris flow, unit: °; is the turbulence coefficient of coarse particles in debris flow, unit: ; , is the acceleration due to gravity, unit: .

[0022] Understandably, and All are calculated from the terrain.

[0023] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: This application combines the theory of continuous medium mechanics, couples the three-phase media of water, coarse particles and fine particles through the continuous medium fluid mechanics model, and uses the finite difference method to realize the numerical simulation of the evolution of the disaster chain of debris flow blocking the river-dam burst flood. This application takes into account the sediment transport effect of the main river flow when the debris flow merges into the main river and the influence of the sediment transport process of the main river on the burst process of the dam and the evolution process of the burst flood. It can simultaneously simulate whether the debris flow blocks the river, how the dam bursts after blocking the river, and the evolution process of the burst flood, realizing the complete coupling process of the physical process of the evolution of the disaster chain of debris flow blocking the river-dam burst flood. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The particle gradation curve of the debris flow of the present invention; Figure 2 This is a numerical simulation diagram of the evolution of debris flow movement - river blocking - dam breach - outburst flood. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] The technical solution of this application is as follows: An embodiment of the present application provides a numerical simulation method for the disaster chain of debris flow blocking a river and a dam breach flood evolution, including: based on a continuous medium fluid mechanics model of coupled water, coarse particles and fine particles three-phase media, obtaining data required for the numerical simulation method, the data including at least one of terrain data, debris flow volume, debris flow starting position, debris flow particle grading, channel soil grading, main river flow, and main river channel roughness coefficient.

[0027] This application combines the theory of continuous medium mechanics, couples the three-phase media of water, coarse particles and fine particles through the continuous medium fluid mechanics model, and uses the finite difference method to realize the numerical simulation of the evolution of the disaster chain of debris flow blocking the river-dam burst flood. This application takes into account the sediment transport effect of the main river flow when the debris flow merges into the main river and the influence of the sediment transport process of the main river on the burst process of the dam and the evolution process of the burst flood. It can simultaneously simulate whether the debris flow blocks the river, how the dam bursts after blocking the river, and the evolution process of the burst flood, realizing the complete coupling process of the physical process of the evolution of the disaster chain of debris flow blocking the river-dam burst flood.

[0028] The numerical simulation method of the debris flow blocking the river-dam burst flood evolution disaster chain in this application first selects a section upstream of the main river to set a main river flow , the volume concentration of coarse sediment transported by the main river , the volume concentration of fine sediment transported by the main river , the volume fraction of the main river water body , and satisfies ; Further set the initial starting position, volume and initial fine particle volume concentration of debris flow , initial coarse particle volume concentration and initial water content in debris fluid ; Then the numerical simulation method of the disaster chain of debris flow blocking the river-dam burst flood evolution is used to simulate the movement of the main river flow; when the main river flow moves to a certain section downstream, the debris flow movement in the debris flow channel is calculated based on the numerical simulation method of the disaster chain of debris flow blocking the river-dam burst flood evolution; when the debris flow merges into the main river, the concentration of coarse and fine particles in the debris flow changes due to the influence of the main river flow, thereby changing the movement resistance and movement state of the debris flow. Finally, based on the numerical simulation method of the disaster chain of debris flow blocking the river-dam burst flood evolution, it is automatically calculated whether the debris flow will block the river and how the burst flood will move after blocking the river.

[0029] In some embodiments, the governing equation of the continuum fluid mechanics model is: ; ; ; In the formula, Depth of debris flow or flood, unit: ; , for debris flow or flood along the Single-width flow in a direction, unit: ; , for debris flow or flood along the Single-width flow in a direction, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; is the density of debris flow or flood burst, unit: ; is the volume concentration of water in a debris flow or flood, unit: dimensionless; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; is the density of particulate matter in debris flow or flood, unit: ; is the density of clean water, unit: ; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional bed resistance, unit: ; The elevation of the terrain required for numerical simulation, unit: ; , is the acceleration due to gravity, unit: ; is the total erosion rate of debris flow or flood, unit: ; The total deposition rate of particulate matter in debris flow or flood burst, unit: ; is time, unit: .

[0030] In some embodiments, the transport equations for water, fine particles, and coarse particles during debris flow or flood outburst are: ; ; ; In the formula, Depth of debris flow or flood, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; is the volume concentration of water in a debris flow or flood, unit: dimensionless; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; is the erosion rate in debris flow or flood, in units: ; It is the volume percentage of water in the channel during the erosion of the channel by debris flow or flood, unit: dimensionless; It is the volume percentage of fine particles in channel materials during debris flow or flood erosion, unit: dimensionless; It is the volume percentage of coarse particles in the channel material during debris flow or flood erosion, unit: dimensionless; is the deposition rate of fine particles in debris flow or flood, unit: ; is the deposition rate of coarse particles in debris flow or flood, in units: ; is the diffusion coefficient of fine particles in debris flow or flood, unit: ; is time, unit: .

[0031] In some embodiments, the evolution equation of the terrain is: ; In the formula, is the trench bed porosity, unit: dimensionless; is the elevation of the terrain, in units: ; is the total deposition rate of debris flow or flood outburst, in units: ; is the total erosion rate of debris flow or flood, unit: ; is the sediment transport rate per unit width along the x direction, unit: ; is the sediment transport rate per unit width along the y direction, unit: ; is time, unit: .

[0032] Furthermore, the diffusion coefficient of fine particles in the fine particle transport equation is The calculation formula is as follows: ; In the formula, is the diffusion coefficient of fine particles in debris flow or flood, unit: ; κ = 0.4 represents the von Karman constant, unit: dimensionless; is the friction velocity of the bed surface of debris flow or flood, unit: ; The total resistance of the bottom of debris flow or flood, unit: ; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional bed resistance, unit: ; is the density of debris flow or flood burst, unit: ; h is the depth of debris flow or flood, unit: .

[0033] Furthermore, in the governing equation, the debris flow or flood erosion rate The calculation method is: ; In the formula, is the total erosion rate of gully bed sediment by outburst floods, unit: ; is the total debris flow erosion rate, unit: ; Γ is the transition factor from outburst flood to debris flow, unit: dimensionless, representing the critical volume concentration of total sediment material that distinguishes outburst flood from debris flow, and the calculation formula is: ; Where α is the attenuation exponent, unit: dimensionless, value is 13.8; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; It is the critical total particulate matter concentration that separates outburst floods from debris flows. Unit: dimensionless, with a value of 0.18.

[0034] Furthermore, The total erosion rate of debris flow The calculation equation is: ; In the formula, The total resistance of the bottom of debris flow or flood, unit: ; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Directional flow velocity, unit: ; is the density of debris flow or flood burst, unit: ; Depth of debris flow or flood burst calculated, unit: ; It is the pore water pressure coefficient in the ditch bed material when debris flow erodes the ditch, unit: dimensionless; is the channel slope, unit: °; It is the friction angle of the granular material in the channel when the debris flow erodes the channel, unit: °; It is the cohesion of the granular material in the channel when the debris flow erodes the channel, unit: ; is the acceleration due to gravity, unit: .

[0035] Understandably, is the channel slope, unit: °, calculated from the terrain.

[0036] Furthermore, The total erosion rate of flood on gully bed sediment is The calculation method is ; In the formula, is the total erosion rate of gully bed sediment by outburst flood, unit: ; is the total resistance of the flood bed, unit: ; For flood breach Directional bed resistance, unit: ; For flood breach Directional bed resistance, unit: ; It is the erosion resistance of the gully bed material during the outburst flood erosion process, unit: ; is the empirical coefficient of outburst flood erosion, unit: .

[0037] Understandably, for and The maximum value of two numbers.

[0038] It can be understood that since the mud and sand particles are fully mixed and have strong integrity during the movement of debris flows, the sedimentation of the mud and sand particles can be ignored, and only the sedimentation of fine and coarse sediment particles during the movement of the flood burst is considered.

[0039] Furthermore, the transport equations for fine and coarse particles are and The calculation method is: ; ; In the formula, is the deposition rate of fine particles in the outburst flood movement, unit: ; is the deposition rate of coarse particles in the outburst flood movement, unit: ; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; It is an empirical parameter, with a value of 2.0-5.0, unit: dimensionless; Γ is the transition factor from flood outburst to debris flow, unit: dimensionless; is the sedimentation rate of fine particles in the outburst flood movement, unit: , the calculation formula is: ; In the formula, is the kinematic viscosity of clean water, unit: ; It is the representative particle size of fine particles in the process of flood burst, unit: ; The density of fine particles in debris flow or flood, unit: ; is the density of clean water, unit: ; is the acceleration due to gravity, unit: ; is the sedimentation rate of coarse particles in the outburst flood movement, unit: , the calculation formula is: ; In the formula, is the kinematic viscosity of clean water, unit: ; It is the representative particle size of coarse particles in the process of flood burst, unit: ; The density of coarse particles in debris flow or flood burst, unit: ; is the density of clean water, unit: ; is the acceleration due to gravity, unit: .

[0040] Further, Sediment transport rate of coarse particles per width along the x direction and the sediment transport rate of coarse particles per width along the y direction The calculation methods are: ; ; In the formula, Debris flow or flood Single-width flow in a direction, unit: ; Debris flow or flood Single-width flow in a direction, unit: ; is the sediment transport rate of coarse particles per width, unit: , the calculation formula is: ; In the formula, is the Froude number of the fluid, unit: dimensionless; Depth of debris flow or flood, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; is the dimensionless bed shear stress, i.e., Shields number; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional bed resistance, unit: ; The density of coarse particles in debris flow or flood burst, unit: ; is the density of clean water, unit: ; It is the representative particle size of coarse particles in the process of flood burst, unit: ; is the acceleration due to gravity, unit: ; is the critical Shields number, unit: dimensionless, calculated as ; In the formula, is the empirical coefficient, unit: dimensionless; is the channel slope, unit: °; It is the friction angle between the granular materials in the channel when the channel is eroded by burst flood, unit: °.

[0041] Further, and Medium debris flow or flood along the Directional bottom resistance and debris flow or flood along the Directional bottom resistance The calculation formula is: ; ; In the formula, is the density of debris flow or flood burst, unit: ; is the volume concentration of water in a debris flow or flood, unit: dimensionless; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; is the density of particulate matter in debris flow or flood, unit: ; is the density of clean water, unit: ; Roughness coefficient of the outburst flood during its movement, unit: ; Depth of debris flow or flood, unit: ; , for debris flow or flood along the Single-width flow in a direction, unit: ; , for debris flow or flood along the Single-width flow in a direction, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; Γ is the transition factor from flood outburst to debris flow, unit: dimensionless; and The liquid slurry of debris flow or flood burst is Direction and Directional bed resistance, unit: ; and The coarse particles of debris flow or flood are Direction and Directional bed resistance, unit: ; is the acceleration due to gravity, unit: .

[0042] Furthermore, the liquid slurry of debris flow or flood bursting Directional bottom resistance and Directional bottom resistance The calculation formulas are: ; ; In the formula, Depth of debris flow or flood, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; is the dynamic viscosity of clean water, unit: Pa·s; Represents the volume concentration of fine particles in liquid mud, unit: dimensionless; It is the maximum allowable volume concentration of fine-grained sediment in liquid mud, unit: dimensionless, calculated as: ; In the formula, and Represents the fine-grained sediment i The diameter and mass percentage of each particle size class, unit: dimensionless; S v0 is the critical volume concentration at which the fluid changes from a Newtonian fluid to a Bingham fluid. Unit: dimensionless. The calculation formula is: ; k 0 is a correction factor, unit: dimensionless, expression: .

[0043] Understandably, It is the maximum allowable volume concentration of fine-grained sediment in liquid mud. Unit: dimensionless. This parameter is usually related to the specific surface area of ​​the particles.

[0044] Furthermore, the coarse particles of debris flow or flood are carried along Directional bottom resistance and Directional bottom resistance The calculation formulas are: ; ; In the formula, The coarse particles in debris flow or flood are The resistance to motion in the direction, in units: ; The coarse particles in debris flow or flood are The resistance to motion in the direction, in units: ; is the density of debris flow or flood burst, unit: ; It is the density of liquid slurry composed of fine particles and water, unit: ; is the volume concentration of water in a debris flow or flood, unit: dimensionless; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; is the density of particulate matter in debris flow or flood, unit: ; is the density of clean water, unit: ; Debris flow or flood Single-width flow in a direction, unit: ; Debris flow or flood Single-width flow in a direction, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; Depth of debris flow or flood, unit: ; The edge of the bottom of a debris flow or flood Slope of direction, unit:°; The bottom edge of the debris flow Slope of direction, unit:°; is the friction angle between coarse particles and the bottom bed in debris flow, unit: °; is the turbulence coefficient of coarse particles in debris flow, unit: ; , is the acceleration due to gravity, unit: .

[0045] Understandably, and All are calculated from the terrain.

[0046] Experimental example A simulation check is carried out using a ditch in Sichuan as an example. The constant flow of the main river downstream of the ditch is 150 m 3 / s (average flow), volume concentration of coarse sediment in the main river upstream of the river =0.01 (unit: dimensionless), the volume concentration of fine particles in the main river =0.03 (unit: dimensionless), the volume fraction of the main river water body is 0.96 (unit: dimensionless), and the riverbed roughness coefficient is 0.035 The total volume of debris flow in this ditch is 98,300 m 3 , the initial fine particle volume concentration in debris fluid is 0.25 (unit: dimensionless), initial coarse particle volume concentration is 0.35 (unit: dimensionless), the initial water content in the debris fluid =0.40 (unit: dimensionless). The volume percentage of water in the channel during the erosion of the channel by debris flow or flood is 0.35 (unit: dimensionless), the volume percentage of coarse particles in the channel material is 0.38 (unit: dimensionless), the volume percentage of fine particles in the channel material is 0.27 (unit: dimensionless), the porosity of the trench bed The value is 0.35 (unit: dimensionless). During the outburst flood movement, the empirical parameters of particle sedimentation , with a value of 3.0 (unit: dimensionless). The density of particulate matter in a debris flow or flood burst , the density of clean water The friction angle between coarse particles and the bottom of debris flow is 28°, and the turbulence coefficient of coarse particles in debris flow is 25.5 . Representative particle size of coarse particles during flood outburst movement The value is 0.01 , The representative particle size of fine particles during flood outburst movement is 0.0005 The friction angle between channel particles when calculating the sediment transport rate of coarse particles per width in flood outburst The erosion resistance of gully bed materials during outburst flood erosion For 30 , The empirical coefficient of flood erosion is 0.00059 (unit: ). The particle grading curve of debris flow is as follows Figure 1 According to the 1:10000 topographic map of the ditch, a digital elevation model (DEM) of the debris flow ditch basin was established. The above parameters were input into the numerical model to obtain the process of debris flow movement, river blocking, and flood outburst evolution as shown in the figure. Figure 2 The results show that under the above parameter conditions, the debris flow can block the downstream main river, and the maximum height of the debris flow dam is 9.84 m. As the upstream main river continues to flow, the water level of the barrier lake rises, and its backwater length is about 362 m. The total storage capacity of the barrier lake is about 18.43×10 4 m 3 The debris flow dam then collapsed rapidly, with a peak flow of 952.2 m 3 / s.

[0047] Figure 2 (a) is the simulation of debris flow movement; (b) is the simulation of debris flow blocking the river; (c) is the simulation of debris flow dam breach process; (d) is the simulation of debris flow dam breach flood evolution.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A numerical simulation method for the disaster chain of debris flow blocking the river and dam burst flood evolution, characterized by: include: Based on a continuous medium fluid mechanics model of coupled water, coarse particles and fine particles three-phase medium, data required for the numerical simulation method are obtained, and the data include at least one of terrain data, debris flow volume, debris flow starting position, debris flow particle grading, channel soil grading, main river flow, and main river roughness coefficient.

2. The numerical simulation method for the disaster chain of debris flow blocking the river and dam breach flood evolution according to claim 1 is characterized in that: The governing equation of the continuum fluid mechanics model is: ； ； ； In the formula, Depth of debris flow or flood, unit: ; , for debris flow or flood along the Single-width flow in a direction, unit: ; , for debris flow or flood along the Single-width flow in a direction, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; is the density of debris flow or flood burst, unit: ; is the volume concentration of water in a debris flow or flood, unit: dimensionless; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; is the density of particulate matter in debris flow or flood, unit: ; is the density of clean water, unit: ; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional bed resistance, unit: ; The elevation of the terrain required for numerical simulation, unit: ; , is the acceleration due to gravity, unit: ; is the total erosion rate of debris flow or flood, unit: ; The total deposition rate of particulate matter in debris flow or flood burst, unit: ; is time, unit: .

3. The numerical simulation method for the disaster chain of debris flow blocking the river and dam breach flood evolution according to claim 1 is characterized in that: The transport equations of water, fine particles and coarse particles during debris flow or flood outburst are: ； ； ； In the formula, Depth of debris flow or flood, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; is the volume concentration of water in a debris flow or flood, unit: dimensionless; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; is the erosion rate in debris flow or flood, in units: ; It is the volume percentage of water in the channel during the erosion of the channel by debris flow or flood, unit: dimensionless; It is the volume percentage of fine particles in channel materials during debris flow or flood erosion, unit: dimensionless; It is the volume percentage of coarse particles in the channel material during debris flow or flood erosion, unit: dimensionless; is the deposition rate of fine particles in debris flow or flood, unit: ; is the deposition rate of coarse particles in debris flow or flood, in units: ; is the diffusion coefficient of fine particles in debris flow or flood, unit: ; is time, unit: .

4. The numerical simulation method for the disaster chain of debris flow blocking the river and dam breach flood evolution according to claim 1 is characterized in that: The evolution equation of the terrain is: ； In the formula, is the trench bed porosity, unit: dimensionless; is the elevation of the terrain, in units: ; is the total deposition rate of debris flow or flood outburst, in units: ; is the total erosion rate of debris flow or flood, unit: ; is the sediment transport rate per unit width along the x direction, unit: ; is the sediment transport rate per unit width along the y direction, unit: ; is time, unit: .

5. The numerical simulation method for the disaster chain of debris flow blocking the river and dam breach flood evolution according to claim 3 is characterized in that: Diffusion coefficient of fine particles in the transport equation of fine particles The calculation formula is as follows: ； In the formula, is the diffusion coefficient of fine particles in debris flow or flood, unit: ; κ = 0.4 represents the von Karman constant, unit: dimensionless; is the friction velocity of the bed surface of debris flow or flood, unit: ; The total resistance of the bottom of debris flow or flood, unit: ; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional bed resistance, unit: ; is the density of debris flow or flood burst, unit: ; h is the depth of debris flow or flood, unit: .

6. The numerical simulation method for the disaster chain of debris flow blocking the river and dam breach flood evolution according to claim 2 is characterized in that: In the governing equation, the erosion rate of debris flow or flood is The calculation method is: ； In the formula, is the total erosion rate of gully bed sediment by outburst floods, unit: ; is the total debris flow erosion rate, unit: ; Γ is the transition factor from outburst flood to debris flow, unit: dimensionless, representing the critical volume concentration of total sediment material that distinguishes outburst flood from debris flow, and the calculation formula is: ； Where α is the attenuation exponent, unit: dimensionless, value is 13.8; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; It is the critical total particulate matter concentration that separates outburst floods from debris flows. Unit: dimensionless, with a value of 0.

18.

7. The numerical simulation method for the disaster chain of debris flow blocking the river and dam breach flood according to claim 6 is characterized in that: Total debris flow erosion rate The calculation equation is: ； In the formula, The total resistance of the bottom of debris flow or flood, unit: ; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Directional flow velocity, unit: ; is the density of debris flow or flood burst, unit: ; Depth of debris flow or flood burst calculated, unit: ; It is the pore water pressure coefficient in the ditch bed material when debris flow erodes the ditch, unit: dimensionless; is the channel slope, unit: °; It is the friction angle of the granular material in the channel when the debris flow erodes the channel, unit: °; It is the cohesion of the granular material in the channel when the debris flow erodes the channel, unit: ; is the acceleration due to gravity, unit: ; and / or Total erosion rate of gully bed sediment by outburst flood The calculation method is ； In the formula, is the total erosion rate of ditch bed sediment by outburst flood, unit: ; is the total resistance of the flood bed, unit: ; For flood breach Directional bed resistance, unit: ; For flood breach Directional bed resistance, unit: ; It is the erosion resistance of the gully bed material during the outburst flood erosion process, unit: ; is the empirical coefficient of flood erosion, unit: .

8. The numerical simulation method for the disaster chain of debris flow blocking the river and dam breach flood according to claim 3 is characterized in that: The transport equations for fine and coarse particles and The calculation method is: ； ； In the formula, is the deposition rate of fine particles in the outburst flood movement, unit: ; is the deposition rate of coarse particles in the outburst flood movement, unit: ; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; It is an empirical parameter, with a value of 2.0-5.0, unit: dimensionless; Γ is the transition factor from flood outburst to debris flow, unit: dimensionless; is the sedimentation rate of fine particles in the outburst flood movement, unit: , the calculation formula is: ； In the formula, is the kinematic viscosity of clean water, unit: ; It is the representative particle size of fine particles in the process of flood burst, unit: ; The density of fine particles in debris flow or flood, unit: ; is the density of clean water, unit: ; is the acceleration due to gravity, unit: ; is the sedimentation rate of coarse particles in the outburst flood movement, unit: , the calculation formula is: ； In the formula, is the kinematic viscosity of clean water, unit: ; It is the representative particle size of coarse particles in the process of flood burst, unit: ; The density of coarse particles in debris flow or flood burst, unit: ; is the density of clean water, unit: ; is the acceleration due to gravity, unit: .

9. The numerical simulation method for the disaster chain of debris flow blocking the river and dam breach flood according to claim 4 is characterized in that: Sediment transport rate of coarse particles per width along the x direction and the sediment transport rate of coarse particles per width along the y direction The calculation methods are: ； ； In the formula, Debris flow or flood Single-width flow in a direction, unit: ; Debris flow or flood Single-width flow in a direction, unit: ; is the sediment transport rate of coarse particles per width, unit: , the calculation formula is: ； In the formula, is the Froude number of the fluid, unit: dimensionless; Depth of debris flow or flood, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; is the dimensionless bed shear stress, i.e., Shields number; Debris flow or flood Directional bed resistance, unit: ; Debris flow or flood Directional bed resistance, unit: ; The density of coarse particles in debris flow or flood burst, unit: ; is the density of clean water, unit: ; It is the representative particle size of coarse particles in the process of flood burst, unit: ; is the acceleration due to gravity, unit: ; is the critical Shields number, unit: dimensionless, calculated as ； In the formula, is the empirical coefficient, unit: dimensionless; is the channel slope, unit: °; It is the friction angle between the granular materials in the channel when the channel is eroded by burst flood, unit: °.

10. The numerical simulation method for the disaster chain of debris flow blocking the river and dam breach flood evolution according to claim 2 is characterized in that: and Medium debris flow or flood along the Directional bottom resistance and debris flow or flood along the Directional bottom resistance The calculation formula is: ； ； In the formula, is the density of debris flow or flood burst, unit: ; is the volume concentration of water in a debris flow or flood, unit: dimensionless; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; is the density of particulate matter in debris flow or flood, unit: ; is the density of clean water, unit: ; Roughness coefficient of the outburst flood during its movement, unit: ; Depth of debris flow or flood, unit: ; , for debris flow or flood along the Single-width flow in a direction, unit: ; , for debris flow or flood along the Single-width flow in a direction, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; Γ is the transition factor from flood outburst to debris flow, unit: dimensionless; and The liquid slurry of debris flow or flood burst is Direction and Directional bed resistance, unit: ; and The coarse particles of debris flow or flood are Direction and Directional bed resistance, unit: ; is the acceleration due to gravity, unit: ; Debris flow or flood liquid slurry along Directional bottom resistance and Directional bottom resistance The calculation formulas are: ； ； In the formula, Depth of debris flow or flood, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; is the dynamic viscosity of clean water, unit: Pa·s; Represents the volume concentration of fine particles in liquid mud, unit: dimensionless; It is the maximum allowable volume concentration of fine-grained sediment in liquid mud, unit: dimensionless, calculated as: ； In the formula, and Represents the fine-grained sediment i The diameter and mass percentage of each particle size grade, unit: dimensionless; S v0 is the critical volume concentration at which the fluid changes from a Newtonian fluid to a Bingham fluid. Unit: dimensionless. The calculation formula is: ； k 0 is a correction factor, unit: dimensionless, expression: ； Debris flow or flood coarse particles along the Directional bottom resistance and Directional bottom resistance The calculation formulas are: ； ； In the formula, The coarse particles in debris flow or flood are The resistance to motion in the direction, in units: ; The coarse particles in debris flow or flood are The resistance to motion in the direction, in units: ; is the density of debris flow or flood burst, unit: ; It is the density of liquid slurry composed of fine particles and water, unit: ; is the volume concentration of water in a debris flow or flood, unit: dimensionless; is the volume concentration of coarse particles in debris flow or flood, unit: dimensionless; is the volume concentration of fine particles in debris flow or flood, unit: dimensionless; is the density of particulate matter in debris flow or flood, unit: ; is the density of clean water, unit: ; Debris flow or flood Single-width flow in a direction, unit: ; Debris flow or flood Single-width flow in a direction, unit: ; Debris flow or flood Directional flow velocity, unit: ; Debris flow or flood Flow velocity in direction, unit: ; Depth of debris flow or flood, unit: ; The edge of the bottom of a debris flow or flood Slope of direction, unit:°; The bottom edge of the debris flow Slope of direction, unit:°; is the friction angle between coarse particles and the bottom bed in debris flow, unit: °; is the turbulence coefficient of coarse particles in debris flow, unit: ; , is the acceleration due to gravity, unit: .

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