Simulation method and system for avalanche-impact blast coupling motion

Abstract

The invention belongs to the technical field of avalanche disaster prevention and reduction, and discloses a simulation method and system for avalanche-impact blast coupling motion. The method comprises the following steps: dividing grids based on DEM; establishing and solving an avalanche subject motion model; establishing an impact blast depth average control model; respectively establishing mass, momentum and turbulence energy conservation equations of the impact blast, wherein mass evolution distinguishes formation and propagation stages and introduces corresponding mass source items; and mass, momentum and energy transfer and coupling solution between the avalanche and the blast are realized through a coupling mechanism. The system comprises corresponding function modules. According to the method, quantitative simulation of the dynamic coupling process of the avalanche-blast composite disaster is achieved, the physical mechanism is clear, the calculation efficiency is high, and the method is suitable for engineering risk assessment and protection design under complex terrains.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of avalanche disaster prevention and mitigation, in particular to a simulation method and system for avalanche-impact airwave coupled motion. BACKGROUND

[0002] Avalanche is one of the common and extremely destructive natural disasters in alpine mountainous areas. Its rapid movement process not only causes direct impact on personnel safety, traffic engineering and infrastructure, but also induces strong impact airwaves during the movement process, significantly expanding the disaster influence range and disaster intensity. Especially in canyon terrain, narrow gullies and near major engineering facilities, the impact airwaves induced by avalanches often exhibit characteristics such as fast propagation speed, long action distance, and high instantaneous pressure, posing a serious threat to bridges, power transmission lines, factories and protective structures.

[0003] Currently, domestic risk assessment and numerical simulation research on avalanche disasters mainly focuses on the avalanche main body movement process itself, usually treating avalanches as a single continuous medium or equivalent sliding body, and focusing on analyzing its flow path, accumulation range and impact force characteristics. In such methods, the impact airwaves induced by avalanches are often simplified and evaluated through a wind force rating table, or even ignored, making it difficult to reflect the real disaster-causing mechanism of avalanche-airwave combined disasters.

[0004] On the other hand, the existing domestic avalanche simulation and evaluation methods mostly use empirical models or static approximation methods, lacking systematic characterization of the formation mechanism, propagation process and dynamic coupling effect between the impact airwaves and the avalanche main body. Especially in the airwave generation stage, the process of the avalanche main body transferring mass, momentum and energy to the airwaves has not yet formed a unified and calculable physical description; in the airwave propagation stage, key processes such as entrainment and wrapping between airwaves and surrounding air, turbulence enhancement and energy dissipation also lack effective numerical simulation means. This technical status leads to difficulties in accurately predicting the speed distribution, pressure characteristics and action range of impact airwaves, limiting the reliability of related engineering protection design and risk assessment.

[0005] From the perspective of engineering application, with the continuous expansion of transportation, power and water conservancy engineering in alpine mountainous areas, avalanche-impact airwave combined disasters pose higher requirements on engineering safety. However, there is still a lack of a numerical simulation method that can simultaneously characterize the movement process of the avalanche main body and the formation and propagation evolution of the impact airwaves induced by it in a unified calculation framework. Therefore, it is necessary to propose a simulation method for avalanche-impact airwave motion that takes into account the calculation efficiency while systematically describing the mass, momentum and energy transfer mechanism between the avalanche main body and the impact airwaves, revealing the formation, propagation and attenuation process of the impact airwaves, to make up for the shortcomings of existing technologies in the field of avalanche-airwave combined disaster simulation. SUMMARY

[0006] In order to overcome the defects of the prior art, the present application provides an avalanche-impact air wave coupling motion simulation method and system with clear physical mechanism and high calculation efficiency.

[0007] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions: In the first aspect, the present application provides an avalanche-impact air wave coupling motion simulation method, comprising the following steps: Grid division is performed on the research area based on a digital elevation model, and each grid unit is used to store state parameters; A motion model of the avalanche body is established and solved to obtain the flow depth, velocity and mass distribution of the avalanche body; A depth-averaged control model of the impact air wave is established, which is regarded as a continuous medium that interacts with the avalanche body but independently evolves; A mass conservation equation of the impact air wave is established, and the mass evolution process of the impact air wave is divided into a formation stage and a propagation stage, and the mass input of the avalanche body and the interaction with the surrounding air are described by introducing a mass source term, respectively; A momentum conservation equation of the impact air wave is established, which is used to simulate the propagation process of the impact air wave under the joint driving of its own physical properties and gravity environment, avalanche momentum input and resistance; A turbulent energy conservation equation of the impact air wave is established, which is used to depict the evolution of turbulent energy in the propagation process of the impact air wave; Through the coupling mechanism between the avalanche body and the impact air wave, mass, momentum and energy transfer between the two are realized, and the motion model of the avalanche body and the control model of the impact air wave are coupled and solved to obtain the spatio-temporal evolution results of the impact air wave motion.

[0008] Preferably, the motion model of the avalanche body is a depth-averaged dynamics model.

[0009] Preferably, the impact air wave can propagate independently after being formed away from the avalanche body.

[0010] Preferably, the specific composition of the mass conservation equation, the specific composition term of the momentum conservation equation, the specific composition term of the turbulent energy conservation equation, and the discrete solving by the finite volume method are adopted.

[0011] In the second aspect, the present application provides an avalanche-impact air wave coupling motion simulation system for realizing the above-mentioned method, comprising a data input and grid division module, an avalanche body motion simulation module, an impact air wave motion simulation module, a coupling solving module and a result output module.

[0012] Preferably, the impact air wave motion simulation module comprises a staged mass conservation calculation unit, a momentum conservation calculation unit and a turbulent energy conservation calculation unit. Preferably, the coupling solving module adopts the finite volume method.

[0013] Compared with the prior art, the present application has the following beneficial effects: 1. By regarding the avalanche body and impact air wave as independent evolving continuous media under a unified computing framework and establishing a coupling mechanism, the dynamic simulation of the whole process of the avalanche-air wave compound disaster is realized, the error caused by simplifying the impact air wave as a static additional load is avoided, the simulation result is more reasonable in physics, and therefore the disaster-causing intensity and range of the compound disaster can be more accurately evaluated.

[0014] 2. By explicitly dividing the mass evolution process of the impact air wave into the formation stage and the propagation stage, and respectively introducing the mass source term input by the avalanche body and the mass source term interacting with the environment air, the different physical mechanisms of the impact air wave from generation to propagation and enhancement are clearly depicted, and the simulation accuracy is significantly improved.

[0015] 3. By the established momentum conservation equation, the gravitational term driven by the physical property difference (such as density difference) of the air wave and air, the momentum source term input by the avalanche, and the motion resistance term are comprehensively considered, so that the whole process of the acceleration, diffusion and deceleration dissipation of the impact air wave under the constraint of topography can be effectively simulated.

[0016] 4. By the established turbulent energy conservation equation, the energy input, generation and dissipation are systematically considered, the evolution characteristics of the intensity of the impact air wave in the propagation process can be depicted, and key parameters for evaluating its destructive power are provided.

[0017] 5. Based on the depth average theory and the finite volume method, while ensuring the accuracy of the description of physical processes, the calculation efficiency is high, and it is suitable for engineering application and risk evaluation under large-scale and complex topography conditions. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings: Figure 1 The simulation method calculation process schematic diagram provided for the embodiments of the present application.

[0019] Figure 2 The avalanche final accumulation simulation diagram provided for the embodiments of the present application.

[0020] Figure 3 The impact air wave maximum speed simulation diagram provided for the embodiments of the present application.

[0021] Figure 4The impact air wave maximum pressure simulation diagram provided for the embodiment of the present application.

[0022] Figure 5 The impact air wave final height simulation diagram provided for the embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0024] The present application provides a simulation method of avalanche-impact air wave coupling motion, comprising the following steps: Step one, grid division is performed on a research region based on a digital elevation model, and each grid unit is used to store state parameters; Step two, a motion model of an avalanche body is established and solved to obtain the flow depth, velocity and mass distribution of the avalanche body; Step three, a depth average control model of impact air wave is established, which is regarded as a continuous medium interacting with the avalanche body but independently evolving; Step four, a mass conservation equation of the impact air wave is established, and the mass evolution process of the impact air wave is divided into a formation stage and a propagation stage, and the mass input of the avalanche body and the interaction with the surrounding air are described by introducing a mass source term, respectively; Step five, a momentum conservation equation of the impact air wave is established, which is used to simulate the propagation process of the impact air wave under the joint driving of its own physical properties and gravity environment, avalanche momentum input and resistance; Step six, a turbulent energy conservation equation of the impact air wave is established, which is used to depict the evolution of turbulent energy in the propagation process of the impact air wave; Step seven, mass, momentum and energy transfer between the avalanche body and the impact air wave are realized through the coupling mechanism between the avalanche body and the impact air wave, and the motion model of the avalanche body and the control model of the impact air wave are coupled and solved to obtain the spatio-temporal evolution results of the impact air wave motion.

[0025] In step two, the motion model of the avalanche body is a depth average dynamics model, and its control equation includes mass conservation, momentum conservation and energy conservation equations.

[0026] In step three, the impact air wave can propagate independently after being formed.

[0027] In step four, the mass conservation equation includes: a formation phase equation, the right side of the equation of which contains a mass source term representing the avalanche mass transfer to the impact airwave; a propagation phase equation, the right side of the equation of which contains a mass source term representing the avalanche mass transfer and a mass source term representing the entrainment of ambient air.

[0028] In step five, the momentum conservation equation contains a gravity term driven by the difference between the airwave density and the air density, a source term representing the avalanche momentum input, and a motion resistance term on the right side of the equation.

[0029] In step six, the turbulent energy conservation equation contains a source term representing the avalanche turbulent energy input, a term representing the turbulent energy generated by the internal shear of the airwave, a term representing the turbulent energy generated by the interaction with the air, and a term representing the turbulent energy dissipation on the right side of the equation.

[0030] In step seven, the finite volume method is used to discretize the space-time of the avalanche body motion model and the impact airwave control equation set, and the evolution results are obtained by step-by-step coupling solution.

[0031] The present application also provides a simulation system for the coupled motion of avalanche-impact airwave, which is used to realize the simulation method, and the system comprises: a data input and grid division module for importing a digital elevation model and performing calculation grid division; an avalanche body motion simulation module for establishing and solving the motion model of the avalanche body; an impact airwave motion simulation module for establishing and solving the depth-averaged control model of the impact airwave; a coupling solution module for realizing the mass, momentum and energy transfer coupling between the avalanche body and the impact airwave, and solving the coupling system composed of the avalanche body motion model and the impact airwave control model; a result output module for outputting the space-time evolution results of the impact airwave velocity, pressure, density and propagation range.

[0032] Further, the impact airwave motion simulation module comprises: a phase-by-phase mass conservation calculation unit for processing the mass evolution of the formation phase and the propagation phase, respectively; a momentum conservation calculation unit for calculating the motion of the impact airwave under various forces; a turbulent energy conservation calculation unit for calculating the intensity change of the impact airwave during propagation.

[0033] The coupling solution module adopts the finite volume method for numerical discretization and solution.

[0034] The technical solutions of the present application will be described clearly and completely in combination with the drawings and embodiments.

[0035] Embodiment 1 As shown in the accompanying drawings, the present embodiment discloses a simulation method of depth-averaged avalanche-impact blast coupling motion, comprising the following steps: Figure 1 Step 1, meshing and data preparation. Based on the digital elevation model (DEM), the study area is discretized into regular calculation grids, and each grid is taken as an independent calculation unit. This step provides a spatial carrier and terrain constraint for all subsequent calculations, which is beneficial to realize fine simulation under complex terrain conditions. Step 2, simulation of avalanche body motion. A depth-averaged dynamics model of the avalanche body is established (an appropriate form known in the art can be used), the mass, momentum and energy conservation equations are solved, and the flow depth, velocity and mass distribution of the avalanche in the motion process are obtained. In the present embodiment, the starting volume of the avalanche is set to 5.5×10 4 m 3 . The result of this step is an important input source for impact blast simulation, providing accurate source data for subsequent coupling. An example of the final accumulation distribution of the avalanche obtained by simulation is shown in

[0036] Figure 2 Step 3, establishment of impact blast control model. The blast induced by the avalanche is regarded as an independent continuous medium, and a depth-averaged control model is established. The impact blast can propagate freely after formation, which makes it possible to more truly reflect the disaster characteristics that the action range of the blast may be far beyond the avalanche accumulation body.

[0037] Step 4, establishment and solution of impact blast mass conservation equation. The mass evolution is divided into formation and propagation stages, which can accurately reflect the differences in dominant physical mechanisms at different stages and is beneficial to improve the physical authenticity of the simulation.

[0038] In the formation stage, the mass is derived from the avalanche body, and the equation is:

[0039] ; In the equation, is the height of the impact blast in the formation stage; is the velocity of the impact blast; is the time; (·) is the divergence operator; is the mass source transmitted from the avalanche body to the impact blast, which is related to the vertical dispersion motion of the avalanche body. This equation describes the generation mechanism of the blast.

[0040] In the propagation stage, the mass sources include avalanche input and air entrainment, and the equation is: ; In the equation, represents the velocity of the impact blast;​​ The height of the air blast during the propagation phase; Density of ice chips; The initial density of the impact blast wave; air density; It can be expressed as This is due to the entrainment effect on the surrounding air, in which... and The air entrainment coefficient. To impact the turbulent energy of the airflow, This represents the air blast density. In this embodiment, the parameter can take the value of... , , Introducing air suction technology It can depict the key process by which air waves increase in mass and expand in volume as they entrain ambient air during propagation.

[0041] Step 5: Establishing and solving the momentum conservation equation for the impact wave. The momentum equation is used to simulate the propagation dynamics of the impact wave and can quantitatively describe its acceleration and deceleration behavior. The equation is as follows: ; In the formula, To withstand the internal stress of the impact blast wave; It is the acceleration due to gravity; The drag force is related to air density, height, velocity, and turbulence intensity, and can be expressed as: ,in, and This is a correction factor, which is the drag coefficient. The function, in this embodiment Take 4. The impact wave under the influence of gravity Initial momentum transferred to the main body of the avalanche Accelerated motion under the action of resistance The deceleration and dissipation are caused by the action.

[0042] Step 6: Establishing and solving the turbulent energy conservation equation for the impact wave. The turbulent energy equation is used to characterize the evolution of the wave intensity, reflecting the mixing and dissipation processes within the wave, and is an important basis for assessing its destructive power. The equation is as follows: ; In the formula, The turbulent capacity transferred to the main body of the avalanche. Turbulent energy generated by interlayer shear of air waves. Turbulent energy generated by interaction with the surrounding air, Controlling the dissipation of turbulent energy.

[0043] Step 7, coupling solution and result output. The models of steps 2 to 6 are integrated through an interface coupling mechanism, and the finite volume method is used for time and space discretization and numerical solution. The coupling solution framework realizes the dynamic interaction of mass, momentum and energy between the avalanche body and the impact air wave, which is the core of the simulation of the compound disaster. The full-field time and space evolution results of the impact air wave movement can be finally obtained. The simulation results of the maximum speed, maximum pressure and final height distribution of the impact air wave in the embodiment are shown in Figs. 8, 9 and 10, respectively. Figure 3 、 Figure 4 、 Figure 5

[0044] Embodiment 2 Correspondingly, the embodiment of the present application also provides a simulation system, which comprises modules corresponding to the above method steps, and is used for automatically executing the above simulation process, and will not be described here.

[0045] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited to this. Any changes or replacements within the technical range disclosed by the present application can be easily thought of by those skilled in the art, and should be covered within the protection scope of the present application.​

Claims

1. A simulation method for avalanche-impact wave coupled motion, characterized in that, Includes the following steps: The study area is divided into grids based on the digital elevation model, and each grid cell is used to store state parameters. Establish and solve the motion model of the avalanche body to obtain the flow depth, velocity and mass distribution of the avalanche body; A depth-averaged control model for the impact wave is established, treating it as a continuous medium that interacts with the avalanche body but evolves independently. A mass conservation equation for the impact wave is established, and the mass evolution process of the impact wave is divided into the formation stage and the propagation stage. The mass input of the avalanche body and its interaction with the surrounding air are described by introducing a mass source term. A momentum conservation equation for the impact wave was established to simulate its propagation process under the combined influence of its own physical properties and the gravitational environment, avalanche momentum input, and drag. A turbulent energy conservation equation for impact waves is established to characterize the evolution of turbulent energy during their propagation. By utilizing the coupling mechanism between the avalanche body and the impact wave, the transfer of mass, momentum, and energy between the two is realized. The motion model of the avalanche body and the control model of the impact wave are coupled and solved to obtain the spatiotemporal evolution results of the impact wave motion.

2. The simulation method for avalanche-impact wave coupled motion according to claim 1, characterized in that, The motion model of the avalanche body is a depth-averaged dynamic model, and its governing equations include mass conservation, momentum conservation, and energy conservation equations.

3. The simulation method for avalanche-impact wave coupled motion according to claim 1, characterized in that, The shock wave, once formed, can detach from the avalanche body and propagate independently.

4. The simulation method for avalanche-impact wave coupled motion according to claim 1, characterized in that, The mass conservation equation includes: The formation stage equation contains a mass source term on the right side of the equation, which represents the mass transfer of the avalanche body to the impact blast wave. The propagation stage equation contains, on its right side, a mass source term representing the mass transferred by the avalanche body and a mass source term representing the entrainment of surrounding air.

5. The simulation method for avalanche-impact wave coupled motion according to claim 4, characterized in that, The momentum conservation equation contains a gravity term driven by the difference between air density and air density, a source term representing the momentum input of the avalanche, and a motion resistance term on the right side.

6. The simulation method for avalanche-impact wave coupled motion according to claim 1 or 4, characterized in that, In the turbulent energy conservation equation, the right side of the equation includes a source term representing the turbulent energy input of the avalanche body, a term representing the turbulent energy generated by internal shearing of the air wave, a term representing the turbulent energy generated by interaction with air, and a term representing the dissipation of turbulent energy.

7. The simulation method for avalanche-impact wave coupled motion according to claim 1, characterized in that, The finite volume method was used to discretize the motion model of the avalanche body and the control equations of the impact wave in time and space, and the evolution results were obtained by solving them through stepwise coupling.

8. A simulation system for avalanche-impact wave coupled motion, used to implement the simulation method for avalanche-impact wave coupled motion as described in any one of claims 1 to 7, characterized in that, The system includes: The data input and grid generation module is used to import digital elevation models and perform computational grid generation. The avalanche motion simulation module is used to establish and solve the motion model of the avalanche body. The shock wave motion simulation module is used to establish and solve the depth-averaged control model of the shock wave. The coupled solution module is used to realize the mass, momentum and energy transfer coupling between the avalanche body and the impact wave, and to solve the coupled system composed of the avalanche body motion model and the impact wave control model. The results output module is used to output the spatiotemporal evolution results of the shock wave velocity, pressure, density, and propagation range.

9. The simulation system for avalanche-impact wave coupled motion according to claim 8, characterized in that, The shock wave motion simulation module includes: A phased mass conservation calculation unit is used to handle the mass evolution of the formation and propagation phases respectively. The momentum conservation calculation unit is used to calculate the motion of impact waves under various forces. The turbulent energy conservation calculation unit is used to calculate the intensity changes during the propagation of impact waves.

10. The simulation system for avalanche-impact wave coupled motion according to claim 8, characterized in that, The coupled solution module uses the finite volume method for numerical discretization and solution.

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