Method and system for simulating dam damage process under debris flow impact

Abstract

The invention belongs to the technical field of geological disaster simulation, and relates to a method and a system for simulating a dam damage process under debris flow impact. The method comprises the following steps: constructing a debris flow depth average two-phase flow model; discretizing the debris flow depth average two-phase flow model by adopting a second-order finite volume method; describing an impact event by adopting a Poisson counting process to obtain time distribution of impact on the giant stone; calculating the impact load containing the elastoplastic deformation stage to obtain the strength distribution of the impact giant stone; and calculating an accumulated damage index according to the time distribution and the strength distribution of the impact event, and updating the geometric parameters of the blocking dam. According to the method, the depth average two-phase model, the impact giant stone randomness probability model and the impact load model are integrated to describe conditions of debris flow propagation and the interception dam in the flowing process, the debris flow propagation process and dam body damage change caused by giant stone impact can be quantitatively described, and the accuracy of a simulation result is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of geological disaster simulation, and in particular, relates to a method and system for simulating the damage process of a retaining dam under the impact of debris flow. Background Art

[0002] Barrier dams are widely used as a key engineering measure to mitigate the risk of debris flows. Debris flows are fast-moving gravity-driven mixtures of water, sediment and rocks, posing a major threat to downstream infrastructure and communities. However, barrier dams are often subjected to extreme dynamic loads generated by debris flows, especially the impact of large rocks entrained in debris flows, resulting in severe structural damage.

[0003] Traditional models (such as the vertical jet model and momentum jump model) are mainly aimed at fine-grained debris flows, and do not fully reflect the high kinetic energy impact characteristics of boulders in rock-rich debris flows. The kinetic energy of boulders is dominant, and their impact stress easily exceeds the local bearing limit of the dam body. However, the existing formula does not quantify the impact of the randomness of boulder size, number and impact sequence on the load, resulting in significant deviations in load estimation. Most existing studies are based on the simulation of single impact events, using finite element analysis or Euler-Lagrangian methods to only evaluate the instantaneous stress distribution and failure mode, without considering the cumulative damage (such as material fatigue and microcrack extension) under repeated debris flow impacts. In actual scenarios, the dam body needs to withstand multiple impacts, and progressive damage will accelerate structural degradation, but there is a lack of relevant long-term performance research.

[0004] Traditional techniques separate structural response from debris flow dynamics, without coupling the interaction between heterogeneous fluid properties (such as the mixed movement of mud and boulders) and dynamic damage to the dam body, which makes it impossible to accurately assess the continued impact of dam body damage after boulder impact on the debris flow regulation capacity (such as flow velocity reduction and sediment interception). Existing risk assessments assume that the dam body structure is intact and ignore the functional attenuation caused by actual damage. This static assumption overestimates the effectiveness of the dam body and may mislead downstream disaster management decisions.

[0005] Although current numerical techniques can simulate single impact events, they lack dynamic modeling of material damage evolution (such as crack merging and stress redistribution) under multiple impacts, making it difficult to quantify the attenuation law of the bearing capacity of the dam during long-term service. Debris flows are heterogeneous, and a more comprehensive study combining structural engineering and fluid dynamics is needed to accurately evaluate the long-term durability of the retaining dam. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a method and system for simulating the damage process of a retaining dam under the impact of debris flow.

[0007] In a first aspect, the present invention provides a method for simulating the damage process of a retaining dam under the impact of debris flow, comprising: Considering the interaction between the solid phase and the fluid phase, a depth-averaged two-phase flow model of debris flow is constructed according to the flow field parameters; the depth-averaged two-phase flow model of debris flow includes the mass conservation equations of the solid phase and the fluid phase, the momentum conservation equation of the fluid phase and the momentum conservation equation of the solid phase; The second-order finite volume method is used to discretize the depth-averaged two-phase flow model of debris flow, and the HLLC Riemann solver is used to update the flow field parameters. The impact events are described by Poisson counting process, and the random probability model of impact boulders is constructed to obtain the time distribution of impact boulders. According to the speed of the impact boulder, the impact load including the elastic-plastic deformation stage is calculated using the Hertz contact theory, and the strength distribution of the impact boulder is obtained; According to the time distribution and intensity distribution of impact events, the cumulative damage index is calculated based on the ratio of plastic zone diameter to residual thickness, and the geometric parameters of the retaining dam are updated.

[0008] In a second aspect, the present invention provides a system for simulating the damage process of a retaining dam under the impact of debris flow, including a model building unit, a parameter updating unit, a time distribution processing unit, an intensity distribution processing unit, and a damage calculation and parameter updating unit; A model building unit is used to consider the interaction between the solid phase and the fluid phase and to build a depth-averaged two-phase flow model of debris flow according to flow field parameters; the depth-averaged two-phase flow model of debris flow includes the mass conservation equations of the solid phase and the fluid phase, the momentum conservation equation of the fluid phase and the momentum conservation equation of the solid phase; A parameter updating unit is used to discretize the depth-averaged two-phase flow model of debris flow using a second-order finite volume method and to update the flow field parameters using an HLLC Riemann solver; A time distribution processing unit is used to describe the impact event using a Poisson counting process, construct a random probability model of the impact boulder, and obtain the time distribution of the impact boulder; A strength distribution processing unit is used to calculate the impact load including the elastic-plastic deformation stage according to the speed of the impact boulder using the Hertz contact theory to obtain the strength distribution of the impact boulder; The damage calculation and parameter updating unit is used to calculate the cumulative damage index based on the time distribution and intensity distribution of the impact event and the ratio of the plastic zone diameter to the residual thickness, and to update the geometric parameters of the retaining dam until the retaining dam fails.

[0009] Based on the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, assuming that the direction of debris flow along the slope is Axis, the debris flow moves perpendicular to the slope axis, For time, is the volume fraction of the fluid phase, is the volume fraction of the solid phase, For the flow to be deep, For fluid phase Directional flow rate, For solid phase Directional flow rate, is the liquid phase flow rate, is the gravitational acceleration The direction of the component, is the gravitational acceleration The direction of the component, is the riverbed elevation, is the fluid phase velocity vector, is the acceleration due to gravity, The relative resistance is The direction component, The relative resistance is The direction of the component, For solid phase Directional flow rate, is Euler's constant, is the base friction angle of the solid phase, is the solid phase velocity vector, is the Manning friction coefficient of the fluid phase, To describe the stress state when the material unit is deformed Earth pressure coefficient in the direction, To describe the stress state when the material unit is deformed The earth pressure coefficient in the direction is: The mass conservation equation for the solid phase is: ; The fluid phase mass conservation equation is: ; Fluid phase The momentum conservation equation in the direction is: ; Fluid phase The momentum conservation equation in the direction is: ; Solid phase The momentum conservation equation in the direction is: ; Solid phase The momentum conservation equation in the direction is: .

[0011] Further, suppose is the resistance correction factor describing the effect of particle concentration, is the drag coefficient, is the density of the fluid phase, is the volume fraction of the solid phase, is the particle diameter, is the particle viscosity, is the fluid viscosity, and the resistance to the change of phase volume fraction is ,but: .

[0012] Furthermore, according to the time distribution and intensity distribution of impact events, the Poisson counting process is used to describe the impact events, and the random probability model of impact boulders is constructed to obtain the time distribution of impact boulders, including: For time, Indicates events that occurred, The boulder impact probability correction factor that represents the influence of the surrounding particle density. is the average rate of events occurring per unit time, Indicates that at a given time interval The number of discrete boulder impact events within The probability representing the number of discrete boulder impact events is obtained from the Poisson distribution: ; set up For the The waiting time before the impact boulder event occurs, and the cumulative distribution function is , the event time follows the gamma distribution, and the cumulative distribution function is expressed as: ; Assume the radius of the boulder is , and is the empirical parameter of radius distribution, and the extreme value distribution function is , is the probability function of the boulder radius, which follows an extreme value distribution: .

[0013] Furthermore, the Hertz contact theory is used to calculate the impact load in the elastic-plastic deformation stage according to the speed of the impact boulder, and the strength distribution of the impact boulder is obtained, including: is the impact pressure of debris flow mud on the retaining dam, is the static component that is linearly and uniformly distributed along the flow depth, is the dynamic component that is linearly and uniformly distributed along the flow depth, is the acceleration due to gravity, For the mud flows deep, is the mud flow rate, is the density of the two-phase mud, then the impact pressure of the debris flow mud on the retaining dam is expressed as: .

[0014] Furthermore, the speed of impacting the boulder is determined according to the viscosity of the mud; assuming that the speed of impacting the boulder is , the boulder radius is The mud viscosity is , is a coefficient related to mud properties. When the fluid viscosity is greater than the set threshold, , when the fluid viscosity is less than or equal to the set threshold, .

[0015] Furthermore, the impact pressure of debris flow mud on the dam body includes static water pressure and dynamic water pressure; is the contact stiffness, is the boulder radius, For time, is the equivalent elastic modulus, , is the contact displacement between the impact boulder and the dam body, and the boulder impact load is , calculate the boulder impact load based on Hertz contact theory: .

[0016] Furthermore, the cumulative damage index is calculated based on the ratio of the plastic zone diameter to the residual thickness, including: is the diameter length of the plastic zone, For the The depth of the permanent indentation caused by the impact is the residual thickness of the impact section of the dam body. , For the The residual thickness of the secondary impact section, is the cumulative damage index, and the cumulative damage index of the first impact is , is the diameter length of the plastic zone, is the remaining thickness of the first impact section, , for The cumulative damage degree of the secondary impact barrier dam is: ; .

[0017] Furthermore, the geometric parameters of the retaining dam are updated until the cumulative damage degree of the retaining dam reaches a set threshold or the number of impacts reaches a set reference value.

[0018] The beneficial effects of the present invention are as follows: the present invention proposes a new numerical method to evaluate the damage evolution of an intercepting dam under the impact of a boulder-rich debris flow. The method integrates a depth-averaged two-phase model, an impact boulder randomness probability model, and an impact load model to describe the conditions of debris flow propagation and the intercepting dam during the flow process. By applying the finite volume method, the dynamics of debris flow propagation and dam damage can be captured while ensuring computational efficiency. The present invention can quantitatively describe the debris flow propagation process and the changes in dam damage caused by boulder impact, thereby improving the accuracy of the simulation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a method for simulating the damage process of a retaining dam under the impact of debris flow provided in Example 1 of the present invention; Figure 2 This is a schematic diagram of a system for simulating the damage process of a retaining dam under the impact of debris flow provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0021] Example 1 As an example, Figure 1 As shown, in order to solve the above technical problems, this embodiment provides a method for simulating the damage process of a retaining dam under the impact of debris flow, including: Considering the interaction between the solid phase and the fluid phase, a depth-averaged two-phase flow model of debris flow is constructed according to the flow field parameters; the depth-averaged two-phase flow model of debris flow includes the mass conservation equations of the solid phase and the fluid phase, the momentum conservation equation of the fluid phase and the momentum conservation equation of the solid phase; The second-order finite volume method is used to discretize the depth-averaged two-phase flow model of debris flow, and the HLLC Riemann solver is used to update the flow field parameters. The impact events are described by Poisson counting process, and the random probability model of impact boulders is constructed to obtain the time distribution of impact boulders. According to the speed of the impact boulder, the impact load including the elastic-plastic deformation stage is calculated using the Hertz contact theory, and the strength distribution of the impact boulder is obtained; According to the time distribution and intensity distribution of impact events, the cumulative damage index is calculated based on the ratio of plastic zone diameter to residual thickness, and the geometric parameters of the retaining dam are updated.

[0022] In order to describe the damage evolution of a retaining dam under the impact of a boulder-rich debris flow, it is necessary to accurately describe the damage evolution of a retaining dam under the impact of a boulder-rich debris flow, describe the dynamics of the debris flow, determine the characteristics of the impact boulders, and estimate the damage to the dam under the impact load. The present invention proposes a debris flow depth-averaged two-phase flow model for describing fluid dynamics, an impact boulder randomness probability model for determining the random characteristics of boulders, and an impact load model for describing dam damage.

[0023] Optionally, assume that the direction of debris flow movement along the slope is Axis, the debris flow moves perpendicular to the slope axis, For time, is the volume fraction of the fluid phase, is the volume fraction of the solid phase, For the flow to be deep, For fluid phase Directional flow rate, For solid phase Directional flow rate, is the liquid phase flow rate, is the gravitational acceleration The direction of the component, is the gravitational acceleration The direction of the component, is the riverbed elevation, is the fluid phase velocity vector, is the acceleration due to gravity, The relative resistance is The direction of the component, The relative resistance is The direction of the component, For solid phase Directional flow rate, is Euler's constant, is the base friction angle of the solid phase, is the solid phase velocity vector, is the Manning friction coefficient of the fluid phase, To describe the stress state when the material unit is deformed Earth pressure coefficient in the direction, To describe the stress state when the material unit is deformed The earth pressure coefficient in the direction is: The mass conservation equation for the solid phase is: ; The fluid phase mass conservation equation is: ; Fluid phase The momentum conservation equation in the direction is: ; Fluid phase The momentum conservation equation in the direction is: ; Solid phase The momentum conservation equation in the direction is: ; Solid phase The momentum conservation equation in the direction is: .

[0024] Debris flow is a typical solid-liquid two-phase flow, and the depth-averaged two-phase flow model of debris flow can effectively capture the typical characteristics. The right side of the momentum conservation equation represents the influence of gravity, fluid pressure gradient, riverbed topography, resistance and friction loss on the debris flow, and the terms on the right side of the solid phase momentum conservation equation represent the influence of gravity, solid phase stress, riverbed topography, resistance and friction loss on the debris flow.

[0025] Optional, set is the resistance correction factor describing the effect of particle concentration, is the drag coefficient, is the density of the fluid phase, is the volume fraction of the solid phase, is the particle diameter, is the particle viscosity, is the fluid viscosity, and the resistance to the change of phase volume fraction is ,but: .

[0026] Debris flows are characterized by the rapid mixing movement of water and heterogeneous particles, occasionally interspersed with boulders of different sizes. During the movement of debris flows, coarse and fine particles interact with each other to form a fluid structure different from that of traditional Newtonian fluids, which can be described by a two-phase model with variable viscosity. However, large boulders do not participate in the fluid structure, but form a lattice structure that supports, superimposes, and inlays with the mud. Debris flows with different viscosity coefficients usually present different movement patterns, among which viscous debris flows show more obvious surge characteristics. Consider a debris flow event in the time domain, and regard the mud surge sequence and boulder appearance as discrete events. The time of mud surge sequence and boulder appearance is random. The discrete impact event of boulders can be described by a Poisson counting process, in which the time of event occurrence is a random variable. The number of discrete boulder impact events in a given time interval is obtained by Poisson distribution.

[0027] The application of Poisson distribution is based on the following assumptions: the number of discrete boulder impact events is zero at the initial moment; there is no overlap between events; the probability of an event occurring in any time increment is asymptotically proportional to the time increment, which means that the process has stationary increments; and the occurrence of events in different time increments is independent. Therefore, the Poisson counting process is a Markov process with discrete states in continuous time.

[0028] Optionally, based on the time distribution and intensity distribution of the impact event, the Poisson counting process is used to describe the impact event, and a random probability model of the impact boulder is constructed to obtain the time distribution of the impact boulder, including: For time, Indicates events that occurred, The boulder impact probability correction factor that represents the influence of the surrounding particle density. is the average rate of events occurring per unit time, Indicates that at a given time interval The number of discrete boulder impact events within The probability representing the number of discrete boulder impact events is obtained from the Poisson distribution: ; set up For the The waiting time before the impact boulder event occurs, and the cumulative distribution function is , the event time follows the gamma distribution, and the cumulative distribution function is expressed as: ; Assume the radius of the boulder is , and is the empirical parameter of radius distribution, and the extreme value distribution function is , is the probability function of the boulder radius, which follows an extreme value distribution: . Hydrodynamic numerical models have difficulty simulating the occurrence, movement and interaction of boulders in mud. Therefore, the present invention uses a combination of impact loads to characterize the combined effects of mud and impact boulders on the barrier. Experimental evidence shows that the impact pressure of debris flow mud on the rigid barrier is proportional to the hydrostatic pressure on the structure, with a proportionality factor ranging from 2.5 to 11.

[0029] Optionally, the impact load including the elastic-plastic deformation stage is calculated using the Hertz contact theory according to the speed of the impact boulder to obtain the strength distribution of the impact boulder, including: is the impact pressure of debris flow mud on the retaining dam, is the static component that is linearly and uniformly distributed along the flow depth, is the dynamic component that is linearly and uniformly distributed along the flow depth, is the acceleration due to gravity, For the mud flows deep, is the mud flow rate, is the density of the two-phase mud, then the impact pressure of the debris flow mud on the retaining dam is expressed as: .

[0030] Optionally, the speed of impacting the boulder is determined according to the viscosity of the mud; let the speed of impacting the boulder be , the boulder radius is The mud viscosity is , is a coefficient related to mud properties. When the fluid viscosity is greater than the set threshold, , when the fluid viscosity is less than or equal to the set threshold, .

[0031] Optionally, the impact pressure of debris flow mud on the dam body includes static water pressure and dynamic water pressure; is the contact stiffness, is the boulder radius, For time, is the equivalent elastic modulus, , is the contact displacement between the impact boulder and the dam body, and the boulder impact load is , calculate the boulder impact load based on Hertz contact theory: .

[0032] Optionally, the cumulative damage index is calculated based on the ratio of the plastic zone diameter to the residual thickness, including: is the diameter length of the plastic zone, For the The depth of the permanent indentation caused by the impact is the residual thickness of the impact section of the dam body. , For the The residual thickness of the secondary impact section, is the cumulative damage index, and the cumulative damage index of the first impact is , is the diameter length of the plastic zone, is the remaining thickness of the first impact section, , for The cumulative damage degree of the secondary impact barrier dam is: ; .

[0033] Optionally, the geometric parameters of the retaining dam are updated until the cumulative damage degree of the retaining dam reaches a set threshold or the number of impacts reaches a set reference value.

[0034] The effectiveness of the proposed method is verified by comparing the numerical results with the results of debris flow channel test and debris flow impact bridge pier test. The simulation results show that the propagation process of debris flow and the change of dam damage caused by boulder impact can be quantitatively described.

[0035] This paper proposes a new numerical method to evaluate the damage evolution of intercepting dams under the impact of boulder-rich debris flows. This method integrates the depth-averaged two-phase model, the random probability model of impact boulders, and the impact load model to describe the conditions of debris flow propagation and intercepting dams during the flow process. By applying the finite volume method, the dynamics of debris flow propagation and dam damage can be captured while ensuring computational efficiency. The verification results show that this method can quantitatively describe the debris flow propagation process and the changes in dam damage caused by boulder impact, and improve the accuracy of the simulation results.

[0036] Example 2 Based on the same principle as the method shown in Example 1 of the present invention, as shown in the attached Figure 2 As shown, an embodiment of the present invention also provides a system for simulating the damage process of a retaining dam under the impact of debris flow, including a model building unit, a parameter updating unit, a time distribution processing unit, an intensity distribution processing unit, and a damage calculation and parameter updating unit; A model building unit is used to consider the interaction between the solid phase and the fluid phase and to build a depth-averaged two-phase flow model of debris flow according to flow field parameters; the depth-averaged two-phase flow model of debris flow includes the mass conservation equations of the solid phase and the fluid phase, the momentum conservation equation of the fluid phase and the momentum conservation equation of the solid phase; A parameter updating unit is used to discretize the depth-averaged two-phase flow model of debris flow using a second-order finite volume method and to update the flow field parameters using an HLLC Riemann solver; A time distribution processing unit is used to describe the impact event using a Poisson counting process, construct a random probability model of the impact boulder, and obtain the time distribution of the impact boulder; A strength distribution processing unit is used to calculate the impact load including the elastic-plastic deformation stage according to the speed of the impact boulder using the Hertz contact theory to obtain the strength distribution of the impact boulder; The damage calculation and parameter updating unit is used to calculate the cumulative damage index based on the time distribution and intensity distribution of the impact event and the ratio of the plastic zone diameter to the residual thickness, and to update the geometric parameters of the retaining dam until the retaining dam fails.

[0037] Optionally, assume that the direction of debris flow movement along the slope is Axis, the debris flow moves perpendicular to the slope axis, For time, is the volume fraction of the fluid phase, is the volume fraction of the solid phase, For the flow to be deep, For fluid phase Directional flow rate, For solid phase Directional flow rate, is the liquid phase flow rate, is the gravitational acceleration The direction of the component, is the gravitational acceleration The direction of the component, is the riverbed elevation, is the fluid phase velocity vector, is the acceleration due to gravity, The relative resistance is The direction of the component, The relative resistance is The direction of the component, For solid phase Directional flow rate, is Euler's constant, is the base friction angle of the solid phase, is the solid phase velocity vector, is the Manning friction coefficient of the fluid phase, To describe the stress state when the material unit is deformed Earth pressure coefficient in the direction, To describe the stress state when the material unit is deformed The earth pressure coefficient in the direction is: The mass conservation equation for the solid phase is: ; The fluid phase mass conservation equation is: ; Fluid phase The momentum conservation equation in the direction is: ; Fluid phase The momentum conservation equation in the direction is: ; Solid phase The momentum conservation equation in the direction is: ; Solid phase The momentum conservation equation in the direction is: .

[0038] Optional, set is the resistance correction factor describing the effect of particle concentration, is the drag coefficient, is the density of the fluid phase, is the volume fraction of the solid phase, is the particle diameter, is the particle viscosity, is the fluid viscosity, and the resistance to the change of phase volume fraction is ,but: .

[0039] Optionally, based on the time distribution and intensity distribution of the impact event, the Poisson counting process is used to describe the impact event, and a random probability model of the impact boulder is constructed to obtain the time distribution of the impact boulder, including: For time, Indicates events that occurred, The boulder impact probability correction factor that represents the influence of the surrounding particle density. is the average rate of events occurring per unit time, Indicates that at a given time interval The number of discrete boulder impact events within The probability representing the number of discrete boulder impact events is obtained from the Poisson distribution: ; set up For the The waiting time before the impact boulder event occurs, and the cumulative distribution function is , the event time follows the gamma distribution, and the cumulative distribution function is expressed as: ; Assume the radius of the boulder is , and is the empirical parameter of radius distribution, and the extreme value distribution function is , is the probability function of the boulder radius, which follows an extreme value distribution: . Optionally, the impact load including the elastic-plastic deformation stage is calculated using the Hertz contact theory according to the speed of the impact boulder to obtain the strength distribution of the impact boulder, including: is the impact pressure of debris flow mud on the retaining dam, is the static component that is linearly and uniformly distributed along the flow depth, is the dynamic component that is linearly and uniformly distributed along the flow depth, is the acceleration due to gravity, For the mud flows deep, is the mud flow rate, is the density of the two-phase mud, then the impact pressure of the debris flow mud on the retaining dam is expressed as: .

[0040] Optionally, the speed of impacting the boulder is determined according to the viscosity of the mud; let the speed of impacting the boulder be , the boulder radius is The mud viscosity is , is a coefficient related to mud properties. When the fluid viscosity is greater than the set threshold, , when the fluid viscosity is less than or equal to the set threshold, .

[0041] Optionally, the impact pressure of debris flow mud on the dam body includes static water pressure and dynamic water pressure; is the contact stiffness, is the boulder radius, For time, is the equivalent elastic modulus, , is the contact displacement between the impact boulder and the dam body, and the boulder impact load is , calculate the boulder impact load based on Hertz contact theory: .

[0042] Optionally, the cumulative damage index is calculated based on the ratio of the plastic zone diameter to the residual thickness, including: is the diameter length of the plastic zone, For the The depth of the permanent indentation caused by the impact is the residual thickness of the impact section of the dam body. , For the The residual thickness of the secondary impact section, is the cumulative damage index, and the cumulative damage index of the first impact is , is the diameter length of the plastic zone, is the remaining thickness of the first impact section, , for The cumulative damage degree of the secondary impact barrier dam is: ; .

[0043] Optionally, the geometric parameters of the retaining dam are updated until the cumulative damage degree of the retaining dam reaches a set threshold or the number of impacts reaches a set reference value.

[0044] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for simulating the damage process of a retaining dam under the impact of debris flow, characterized in that: include: Considering the interaction between solid and fluid phases, a depth-averaged two-phase flow model of debris flow is constructed based on flow field parameters. The depth-averaged two-phase flow model of debris flow includes the mass conservation equations of the solid phase and the fluid phase, the momentum conservation equation of the fluid phase and the momentum conservation equation of the solid phase; The second-order finite volume method is used to discretize the depth-averaged two-phase flow model of debris flow, and the HLLC Riemann solver is used to update the flow field parameters. The impact events are described by Poisson counting process, and the random probability model of impact boulders is constructed to obtain the time distribution of impact boulders. According to the speed of the impact boulder, the impact load including the elastic-plastic deformation stage is calculated using the Hertz contact theory, and the strength distribution of the impact boulder is obtained; According to the time distribution and intensity distribution of impact events, the cumulative damage index is calculated based on the ratio of plastic zone length to residual thickness, and the geometric parameters of the retaining dam are updated.

2. The method for simulating the damage process of a retaining dam under the impact of debris flow according to claim 1 is characterized in that: Assume that the direction of debris flow along the slope is Axis, the debris flow moves perpendicular to the slope axis, For time, is the volume fraction of the fluid phase, is the volume fraction of the solid phase, For the flow to be deep, For fluid phase Directional flow rate, For the solid phase Directional flow rate, is the liquid phase flow rate, is the gravitational acceleration The direction of the component, is the gravitational acceleration The direction of the component, is the riverbed elevation, is the fluid phase velocity vector, is the acceleration due to gravity, The relative resistance is The direction of the component, The relative resistance is The direction of the component, For the solid phase Directional flow rate, is Euler's constant, is the base friction angle of the solid phase, is the solid phase velocity vector, is the Manning friction coefficient of the fluid phase, To describe the stress state when the material unit is deformed Earth pressure coefficient in the direction, To describe the stress state when the material unit is deformed The earth pressure coefficient in the direction is: The mass conservation equation for the solid phase is: ； The fluid phase mass conservation equation is: ； Fluid phase The momentum conservation equation in the direction is: ； Fluid phase The momentum conservation equation in the direction is: ； Solid phase The momentum conservation equation in the direction is: ； Solid phase The momentum conservation equation in the direction is: 。 3. The method for simulating the damage process of a retaining dam under the impact of debris flow according to claim 1 is characterized in that: set up is the resistance correction factor describing the effect of particle concentration, is the drag coefficient, is the density of the fluid phase, is the volume fraction of the solid phase, is the particle diameter, is the particle viscosity, is the fluid viscosity, and the resistance to the change of phase volume fraction is ,but: 。 4. The method for simulating the damage process of a retaining dam under the impact of debris flow according to claim 1 is characterized in that: According to the time distribution and intensity distribution of impact events, the Poisson counting process is used to describe the impact events, and the random probability model of impact boulders is constructed to obtain the time distribution of impact boulders, including: For time, Indicates events that occurred, The boulder impact probability correction factor that represents the influence of the surrounding particle density. is the average rate of events occurring per unit time, Indicates that at a given time interval The number of discrete boulder impact events within The probability representing the number of discrete boulder impact events is obtained from the Poisson distribution: ； set up For the The waiting time before the impact boulder event occurs, and the cumulative distribution function is , the event time follows the gamma distribution, and the cumulative distribution function is expressed as: ； Assume the radius of the boulder is , and is the empirical parameter of radius distribution, and the extreme value distribution function is , is the probability function of the boulder radius, which follows an extreme value distribution: 。 5. The method for simulating the damage process of a retaining dam under the impact of debris flow according to claim 1 is characterized in that: According to the speed of the impact boulder, the Hertz contact theory is used to calculate the impact load including the elastic-plastic deformation stage, and the strength distribution of the impact boulder is obtained, including: is the impact pressure of debris flow mud on the retaining dam, is the static component that is linearly and uniformly distributed along the flow depth, is the dynamic component that is linearly and uniformly distributed along the flow depth, is the acceleration due to gravity, For the mud flows deep, is the mud flow rate, is the density of the two-phase mud, then the impact pressure of the debris flow mud on the retaining dam is expressed as: 。 6. The method for simulating the damage process of a retaining dam under the impact of debris flow according to claim 5 is characterized in that: The speed of impacting the boulder is determined according to the viscosity of the mud; let the speed of impacting the boulder be , the boulder radius is The mud viscosity is , is a coefficient related to mud properties. When the fluid viscosity is greater than the set threshold, , when the fluid viscosity is less than or equal to the set threshold, .

7. The method for simulating the damage process of a retaining dam under the impact of debris flow according to claim 1 is characterized in that: The impact pressure of debris flow mud on the dam body includes static water pressure and dynamic water pressure. is the contact stiffness, is the boulder radius, For time, is the equivalent elastic modulus, , is the contact displacement between the impact boulder and the dam body, and the boulder impact load is , calculate the boulder impact load based on Hertz contact theory: 。 8. The method for simulating the damage process of a retaining dam under the impact of debris flow according to claim 1 is characterized in that: The cumulative damage index is calculated based on the ratio of plastic zone diameter to residual thickness, including: is the diameter length of the plastic zone, For the The depth of the permanent indentation caused by the impact is the residual thickness of the impact section of the dam body. , For the The residual thickness of the secondary impact section, is the cumulative damage index, and the cumulative damage index of the first impact is , is the diameter length of the plastic zone, is the remaining thickness of the first impact section, , for The cumulative damage degree of the secondary impact barrier dam is: ； 。 9. The method for simulating the damage process of a retaining dam under the impact of debris flow according to claim 1, characterized in that: The geometric parameters of the retaining dam are updated until the cumulative damage degree of the retaining dam reaches the set threshold or the number of impacts reaches the set reference value.

10. The simulation system of the damage process of the retaining dam under the impact of debris flow is characterized by: It includes a model building unit, a parameter updating unit, a time distribution processing unit, an intensity distribution processing unit, and a damage calculation and parameter updating unit; A model building unit is used to consider the interaction between the solid phase and the fluid phase and to build a depth-averaged two-phase flow model of debris flow according to flow field parameters; the depth-averaged two-phase flow model of debris flow includes the mass conservation equations of the solid phase and the fluid phase, the momentum conservation equation of the fluid phase and the momentum conservation equation of the solid phase; A parameter updating unit is used to discretize the depth-averaged two-phase flow model of debris flow using a second-order finite volume method and to update the flow field parameters using an HLLC Riemann solver; A time distribution processing unit is used to describe the impact event using a Poisson counting process, construct a random probability model of the impact boulder, and obtain the time distribution of the impact boulder; A strength distribution processing unit is used to calculate the impact load including the elastic-plastic deformation stage according to the speed of the impact boulder using the Hertz contact theory to obtain the strength distribution of the impact boulder; The damage calculation and parameter updating unit is used to calculate the cumulative damage index based on the time distribution and intensity distribution of the impact event and the ratio of the plastic zone diameter to the residual thickness, and to update the geometric parameters of the retaining dam until the retaining dam fails.

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