A meshless simulation method, device and medium for calculating soil landslide surge

Abstract

This invention belongs to the field of geological disaster simulation technology for dikes, specifically involving a meshless simulation method, device, and medium for calculating landslide surge waves. This invention solves the problem of inaccurate inversion of local water pressure and soil contour development processes at the coupling interface. It can effectively characterize the two-phase coupling effect between the landslide body and water body, reasonably simulate the pressure distribution at the coupling interface, eliminate non-physical high-pressure gaps, accurately predict the large deformation movement process of the soil and the surge wave propagation process, and accurately invert the local water impact and turbulence flow state, providing visualized analysis materials. The meshless simulation device for calculating landslide surge waves provided by this invention can accurately simulate various working conditions such as fast and slow landslide surge waves, and can be applied to relevant research and analysis in typical sections and regions, providing guidance for clarifying the evolution law of landslide surge waves and the prevention and control of surge wave disasters. This invention can accurately simulate the entire process of landslide surge waves.

Description

Technical fields:

[0001] This invention belongs to the field of geological disaster simulation technology for dikes, specifically relating to a meshless simulation method, device and medium for calculating landslide surge waves. Background technology:

[0002] In levee construction and geological disaster early warning analysis, secondary disasters caused by landslides and surges are crucial research topics. The process of landslides caused by the instability and failure of water-adjacent soil slopes, and the subsequent surges induced by the landslide entering the water, involves complex fluid-structure interaction. Elucidating this mechanism is of great significance for effectively reversing the evolution of landslide surges and establishing geological disaster early warning systems.

[0003] In existing numerical simulation studies, the large deformation characteristics of soil and water bodies, as well as the different governing equations between them, present certain technical challenges in conducting related multiphase coupling calculations. Existing coupling algorithms are unreliable in retrieving local water pressure and soil contour development processes, resulting in significant errors in the obtained surge amplitude and soil contour development trajectory. Therefore, existing numerical simulation methods cannot accurately simulate the entire process of landslide surges. Summary of the Invention:

[0004] This invention is proposed to address the above-mentioned shortcomings, and aims to provide a meshless simulation method, device, and medium for calculating landslide surge waves, which can solve the technical problem that existing numerical simulation methods cannot accurately simulate the entire process of landslide surge waves.

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

[0006] This invention designs a meshless simulation method for calculating landslide surge waves, comprising the following steps:

[0007] Step 1: Accurately model the engineering area under study to determine the landslide and water body shape characteristics of the site;

[0008] Step 2: Discretize the computational domain and perform secondary corrections on irregular soil and water boundary particles to determine the relevant material property parameters required for the calculation.

[0009] Step 3: Calculate the stress in the unstable soil area of ​​the landslide. Under the premise of ensuring the accuracy of the landslide simulation, select an appropriate discrete element contact model and discrete element scale, and use the discrete element method to calculate the acceleration of each area of ​​the landslide body.

[0010] Step 4: The simulation calculation of water body and surge adopts the smooth particle dynamics method. The river water body region is discretized into a series of fluid particles, and the calculation is performed by the Navier-Stokes equation in integral form to ensure that the size of fluid particles is close to that of discrete elements.

[0011] Step 5: Calculate the normal coupling force between the soil and water. The calculation process follows the optimized fully analytical algorithm, and the normal coupling acceleration is calculated based on the following formula:

[0012]

[0013] In the formula: Du i / D t Represents coupling acceleration, i represents discrete particle i, j represents discrete particle j, u i This represents the calculation of the velocity of particle i, where t is time and p is the velocity of particle i. i and p j The fluid pressures of particles i and j are respectively (refer to formula (3) for calculating soil particle pressure during the coupled calculation process), ρ i Let be the density of particle i, and W be the kernel function. W is the displacement partial differential form of the kernel function. ij V represents the kernel function value at the relative positions of particles i and j. j Let μ be the volume of particle j. i and μ j The viscosity coefficients of particles i and j are respectively, r ij Let be the distance between particles i and j, h be the smooth length, and g be the gravitational acceleration, with a value of -9.81 m / s². 2 γ = 7, c0 is the artificial speed of sound, ρ 0χ For the reference density of phase χ, F coupling For coupling force, m i Let Γ be the mass of particle i, and let Γ be the set of particles that are coupled with particle i. The calculation process of the tangential coupling force between soil and water bodies refers to the discrete format of the non-analytical empirical formula.

[0014] Step 6: Calculate the resultant acceleration of each particle in the discrete computational domain, update the velocity and position within a single time step, and store the target time data. Repeat steps 1 to 3 until the computation time requirement is met.

[0015] Step 7: Read the exported data, perform visualization processing, and conduct subsequent image analysis to meet the calculation requirements.

[0016] Preferably, the meshless simulation method for calculating landslide surge provided by the present invention may also have the following features: in step 2, the discretization of the landslide and water body can be achieved by using existing preprocessing tools to generate a series of coordinate nodes that are close to each other and evenly distributed, so as to characterize the actual contours of the landslide and water body and provide initial conditions for subsequent calculations.

[0017] Preferably, the meshless simulation method for calculating landslide surge waves provided by the present invention may also have the following feature: Step 3 specifically includes the following sub-steps:

[0018] Step 3.1: Set the series of discrete nodes located within the soil region as Discrete Element Method (DEM) particles with a radius of 0.5 times the distance between discrete nodes. Obtain the macroscopic soil deformation process by calculating the cumulative microscopic displacement of the particles under stress.

[0019] Step 3.2, the formula for calculating the contact force between discrete particle elements is shown below:

[0020] F n =k n δ n n+F ndamp (4)

[0021] F t =max|(F t ) T-Δt +k t δ t +F tdamp ,μ||F n || (5) In the formula: F n For normal contact force, F t For tangential contact force, δ n δ is the normal overlap between particles, n is the direction of the line connecting the centers of the two particles, and δ is the normal overlap between particles. t δ represents the tangential overlap between particles. t F represents the relative displacement between contact positions within a single time step. ndamp With F tdamp These represent the normal and tangential damping forces, respectively. t ) T-Δt The tangential contact force at the particle contact surface at the end of the previous time step is given by k, μ is the coefficient of kinetic friction between the particles, and the smaller of the two coefficients is taken. n With k t These are the normal and tangential stiffnesses of the contact interface, respectively, and the Hertz-Mindlin contact model is used for their calculation.

[0022]

[0023] In the formula: G*=0.5(G i +G j ), R*=2R i R j / (R i +R j ), v * =0.5(v) i+v j ), where i and j represent particle i and particle j respectively; G is the shear modulus, G i and G j Let i and j represent the shear modulus of particles i and j, respectively, and R be the particle radius. i and R j Let i and j represent the particle radii, respectively, and v be Poisson's ratio. i and v j Let s represent the Poisson's ratios of particles i and j, respectively. overlap This represents the contact overlap distance between particle i and particle j;

[0024] Step 3.3: The resultant force on a single particle in contact is calculated using the following formula:

[0025]

[0026] In the formula: F n total，i F is the net normal force acting on a single particle in contact. t total,i F is the net tangential force acting on a single particle in contact. n，ij F is the normal contact force between particle i and particle j. t，ij Let N be the tangential contact force between particle i and particle j, and let N represent the set of particles in contact with particle i.

[0027] Preferably, the meshless simulation method for calculating landslide surge waves provided by the present invention may also have the following feature: Step 4 specifically includes the following sub-steps:

[0028] Step 4.1: The water body discretization method selected is the Smoothed Particle Hydrodynamics (SPH) method. A series of discrete nodes located in the water body region are set as SPH particles with a radius equal to the distance between discrete nodes. The macroscopic water body evolution process is obtained by calculating the cumulative microscopic displacement of the particles under force.

[0029] Step 4.2, the force calculation for fluid particles refers to the following formula:

[0030]

[0031] Where: Dρ i / D t Du is the density gradient of particle i. i / D t Let ρ be the coupling acceleration of particle i. i and ρ j The densities of particles i and j are given by denoted as i and j, respectively, where t is time and u is the density of particles i and j. j and u iThese are the velocity vectors of particles j and i, respectively. W is the displacement partial differential form of the kernel function. ij The kernel function values ​​represent the relative positions of particles i and j, m. j Let p be the mass of particle j. i and p j Let be the fluid pressures of particles i and j, respectively, and c0 be the artificial speed of sound. To ensure the assumption of weak compressibility of the fluid, the density gradient of SPH particles must be less than 1%. Therefore, the value of c0 must be no less than 10 times the maximum velocity of the flow field. i and r j These are the displacement vectors of particles i and j, respectively, and ρ0 is the reference density (the density of water is taken as 1000 kg / m³ at 20℃ and one standard atmosphere). 3 ), u ij Let be the velocity vector difference between particles i and j, δ be the density diffusion term, μ be the viscosity coefficient, γ = 7, and g be the gravitational acceleration, taken as -9.81 m / s². 2 W is the kernel function. ij =W(r) i -r j ,h), in the format:

[0032]

[0033] In the formula: q=||r i -r j || / h,α dim It is a parameter related to the calculation dimension; in the two-dimensional case, it is taken as 7 / (4πh). 2 Under three-dimensional working conditions, take 21 / (16πh) 3 The smooth length h is usually taken as 1.5 to 2 times the initial particle spacing in two-dimensional cases and as 1.5 times the particle spacing in three-dimensional cases to ensure the accuracy of the calculation.

[0034] Step 4.3, the internal forces acting on a single-fluid particle are calculated using the following formula:

[0035]

[0036] In the formula: u i This is the calculated velocity vector of a single particle.

[0037] Preferably, the meshless simulation method for calculating landslide surge waves provided by the present invention may also have the following feature: Step 5 specifically includes the following sub-steps:

[0038] Step 5.1: Perform solid and liquid phase particle retrieval at the coupling interface, modify the properties of solid phase particles within the influence domain of fluid particles, and assign them the characteristics of fluid SPH particles of the same density.

[0039] Step 5.2: Calculate the coupling force between soil and water. The normal and tangential forces between particles are calculated according to different analytical formats. The calculation of the normal force refers to the fully analytical format algorithm. For specific calculation, see formulas (1) to (3).

[0040] Step 5.3: The formula for calculating tangential force is a non-analytical empirical format. The specific calculation formula is as follows:

[0041]

[0042] In the formula: i and k represent fluid particle i and soil particle k, respectively. The tangential force acting on particle k V is the tangential force acting on particle i. i and V j Let m be the volume of particles i and j, respectively. i Let p be the mass of fluid particle i. i Let represent the fluid particle pressure, W be the kernel function, εk be the local porosity of particle k, and uk be the average velocity of particle k. W represents the average velocity of the fluid particles surrounding particle k after interpolation, where Ω and Ω' both represent the set of particles interacting with the target particle. ik and W jk Let i and k represent the kernel function values ​​at the relative positions of particles i, k and j, k, respectively, and η be the interphase momentum transfer coefficient, which is related to the local average porosity and relative velocity.

[0043]

[0044] Where: μ f The viscosity coefficient of the fluid (at 20℃ and one standard atmosphere, water is taken as 1.0 × 10⁻⁶) -3 Pa·s), R k Where ρ is the particle radius of the DEM. f For fluid density (under standard operating conditions, water is taken as 1.0 × 10⁻⁶),... 3 kg / m 3 ), C d The drag coefficient is shown below; further calculation details are as follows:

[0045]

[0046] Where: ε k Let ε be the local porosity of particle k. i Let W be the local porosity of particle i. ik V represents the kernel function value at the relative positions of particles i and k. k Let m be the volume of particle k. i R is the mass of fluid particle i. k Re represents the particle radius of the DEM.k Let be the Reynolds number of the flow field near the particle.

[0047] Preferably, the meshless simulation method for calculating landslide surge waves provided by the present invention may also have the following feature: Step 6 specifically includes the following sub-steps:

[0048] Step 6.1: Update the prediction step and correction step within a single time step:

[0049]

[0050] In the formula: Let be the velocity vector of particle i after the (n+1 / 2)th step. Let be the velocity vector of particle i after step (n), and Δt be the time step. Let i be the acceleration vector of particle i after step (n). Let be the angular velocity vector of particle i after the (n+1 / 2)th step. Let be the angular velocity vector of particle i after step (n). Let be the angular acceleration vector of particle i after step (n). Let be the turning angle of particle i after the (n+1 / 2)th step. Let i be the turning angle of particle i after step (n). Let i be the density of particle i after the (n+1 / 2)th step. Let be the density of particle i after step (n). Let be the density gradient of particle i after step (n). Let r be the displacement vector of particle i after the (n+1 / 2)th step. i n Let be the displacement vector of particle i after step (n). Let i be the velocity vector of particle i after step (n). The fluid pressure after step (n+1 / 2) is... The density after the (n+1 / 2)th step is f, which is the proportionality coefficient. The calculation format is based on formula (12).

[0051] Formula (23) is a simplified expression of the state equation. After the prediction step, parameters such as velocity u, angular velocity ω, angular displacement θ, density ρ, linear displacement r, and fluid pressure p can be obtained for the (n+1 / 2)th step. These parameters are used to calculate the continuity equation and momentum equation of SPH and DEM to obtain the acceleration a for the (n+1 / 2)th step. i n+1 / 2 Density gradient (Dρ / Dt) i n+1 / 2 These parameters are used to prepare for the next step of correction.

[0052] Step 6.2, Correction Step:

[0053]

[0054] In the formula: Let be the velocity vector of particle i after the (n+1 / 2)th step. Let be the velocity vector of particle i after step (n), and Δt be the time step. Let be the acceleration vector of particle i after the (n+1 / 2)th step. Let be the angular velocity vector of particle i after the (n+1 / 2)th step. Let be the angular velocity vector of particle i after step (n). Let be the angular acceleration vector of particle i after the (n+1 / 2)th step. Let be the turning angle of particle i after the (n+1 / 2)th step. Let i be the turning angle of particle i after step (n). Let i be the density of particle i after the (n+1 / 2)th step. Let be the density of particle i after step (n). Let be the density gradient of particle i after the (n+1 / 2)th step. Let r be the displacement vector of particle i after the (n+1 / 2)th step. i 2 Let be the displacement vector of particle i after step (n);

[0055] Step 6.3, Parameter Update:

[0056]

[0057] p n+1 =f(ρ n+1 (27) In the formula: Let be the velocity vector of particle i after step (n+1). Let be the velocity vector of particle i after the (n+1 / 2)th step. Let i be the velocity vector of particle i after step (n). Let be the angular velocity vector of particle i after the (n+1)th step. Let be the angular velocity vector of particle i after the (n+1 / 2)th step. Let be the angular velocity vector of particle i after step (n). Let be the turning angle of particle i after the (n+1)th step. Let be the turning angle of particle i after the (n+1 / 2)th step. Let i be the turning angle of particle i after step (n). Let be the density of particle i after step (n+1). Let i be the density of particle i after the (n+1 / 2)th step. Let r be the density of particle i after step (n). i n+1 Let be the displacement vector of particle i after the (n+1)th step. Let r be the displacement vector of particle i after the (n+1 / 2)th step. i n p is the displacement vector of particle i after step (n); n+1 ρ is the fluid pressure after step (n+1). n+1 The density after step (n+1) is f, which is the proportionality coefficient. The calculation format is based on formula (12).

[0058] In the DEM-SPH framework, the time steps of the two modules are kept consistent and determined according to the following formula (28):

[0059]

[0060] In the formula: Δt is the duration of a single step, Δt DEM Δt represents the single-step duration of DEM particles. SPH The single-step duration of SPH particles, in m i Let i be the mass of the discrete element i, and k be the mass of the particle. ni h is the maximum contact stiffness of discrete element i. i Where is the smooth length of the SPH particle, v is the kinematic viscosity of the fluid, and a i Here, c0 is the particle acceleration, and u is the artificial speed of sound. max This represents the maximum flow velocity in the flow field.

[0061] Preferably, the meshless simulation method for calculating landslide surge waves provided by the present invention may also have the following characteristics: in step 6, the calculations of the soil and water frames in the overall simulation method are independent of each other, and the coupling force calculated in step 5 is added as an additional term to the two frames at each time step. Overall, the proposed coupling model is a semi-analytical model, the buoyancy calculation is directly solved using a multiphase flow model, while the drag force calculation is based on a non-analytical empirical formula.

[0062] Preferably, the meshless simulation method for calculating landslide surge waves provided by the present invention may also have the following features: in step 7, the processing of the exported data can be achieved with the help of existing open source post-processing software, and subsequent analysis and research can be carried out in specific local, planar, three-dimensional, animation and other forms to visualize the model update.

[0063] This invention also designs a meshless simulation device for calculating landslide surge waves, which can automatically implement the above-mentioned <method>, including:

[0064] The modeling module accurately models the engineering area under study and determines the landslide and water body shape characteristics of the site.

[0065] The preprocessing module discretizes the computational domain, performs secondary corrections on irregular soil and water boundary particles, and determines the relevant material property parameters required for the calculation.

[0066] The soil landslide simulation module calculates the stress in the unstable soil area of ​​the landslide. Under the premise of ensuring the accuracy of the landslide simulation, a suitable discrete element contact model and discrete element scale are selected, and the discrete element method is used to calculate the acceleration of each area of ​​the landslide body.

[0067] The surge simulation module uses the smooth particle dynamics method to simulate and calculate water bodies and surges. The river water body region is discretized into a series of fluid particles, and the calculation is performed using the Navier-Stokes equations in integral form to ensure that the size of the fluid particles is close to that of the discrete elements.

[0068] The landslide surge coupling calculation module calculates the normal coupling force between soil and water. The calculation process follows an optimized fully analytical algorithm, and the normal coupling acceleration is calculated based on the following formula:

[0069]

[0070] In the formula: Du i / D t The coupling acceleration represents particle i, where i represents discrete particle i, j represents discrete particle j, and u i This represents the calculation of the velocity of particle i, where t is time and p is the velocity of particle i. i and p j The fluid pressures ρ for particles i and j are respectively. i Let be the density of particle i, and W be the kernel function. W is the displacement partial differential form of the kernel function. ij V represents the kernel function value at the relative positions of particles i and j. j Let μ be the volume of particle j. i and μ j The viscosity coefficients of particles i and j are respectively, r ij Let be the distance between particles i and j, h be the smooth length, and g be the gravitational acceleration, with a value of -9.81 m / s². 2 γ = 7, c0 is the artificial speed of sound, ρ 0χ For the reference density of phase χ, F coupling For coupling force, m i Let Γ be the mass of particle i, and let Γ be the set of particles that are coupled with particle i.

[0071] The time step update module calculates the resultant acceleration of each particle in the discrete computation domain, performs velocity and position updates within a single time step, stores target time data, and repeats steps 1 to 3 until the computation time requirement is met.

[0072] The post-processing module reads the exported data, performs visualization processing, and conducts subsequent image analysis to meet computational requirements.

[0073] The control module is communicatively connected to the modeling module, the preprocessing module, the landslide simulation module, the surge simulation module, the landslide-surge coupling calculation module, the time step update module, and the postprocessing module, and controls their operation.

[0074] Preferably, the meshless simulation device for calculating landslide surge provided by the present invention may also have the following features: generalized modeling of actual engineering projects, dividing key research areas, generating numerical models in STL or DXF format, importing them into preprocessing software, performing mesh generation, generating node coordinates and importing them into subsequent calculation modules.

[0075] The beneficial effects of this invention are:

[0076] This invention provides a meshless simulation method, device, and medium for calculating landslide surge waves. It solves the problems of inaccurate inversion of local water pressure and soil contour development processes at the coupling interface. It effectively characterizes the two-phase coupling effect between the landslide body and water body, and accurately simulates the induced propagation process of landslide surge waves. It can reasonably simulate the pressure distribution at the coupling interface, eliminate non-physical high-pressure gaps, accurately predict the large deformation movement process of the soil and the surge wave propagation process, and accurately invert the local water impact and turbulence flow state, providing visualized analysis materials. The meshless simulation device for calculating landslide surge waves provided by this invention can accurately simulate various working conditions such as fast and slow landslide surge waves, and can be applied to relevant research and analysis in typical sections and regions, providing guidance for clarifying the evolution law of landslide surge waves and the prevention and control of surge wave disasters. Therefore, this invention can accurately simulate the entire process of landslide surge waves. Attached image description:

[0077] Figure 1 This is a flowchart of the meshless simulation method of the present invention.

[0078] Figure 2 This is a schematic diagram of the landslide, water body, and terrain involved in the embodiments of the present invention.

[0079] Figure 3 This is a schematic diagram of the particle retrieval method according to an embodiment of the present invention.

[0080] Figure 4 This is a flowchart illustrating the particle contact retrieval process according to an embodiment of the present invention.

[0081] Figure 5 The diagram shows the simulated outlines of the water body and landslide body involved in the embodiments of the present invention.

[0082] Figure 6 This is a graph showing the change in surge height at the wave height meter in working condition 1 of this embodiment of the invention.

[0083] Figure 7 This is a graph showing the change in surge height at the wave height meter in working condition 2 of this embodiment of the invention. Detailed implementation method:

[0084] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and not for limiting the present invention. Furthermore, it should be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, not all of them.

[0085] The Discrete Element Method (DEM) and the Smoothed Particle Hydrodynamics (SPH) methods are suitable for studying the mechanical properties of soil and water due to their meshless properties. The DEM-SPH coupling framework is also gradually being applied to the field of landslide surge simulation.

[0086] This invention relates to a meshless simulation method, apparatus, and medium for calculating landslide surge waves in soil. Based on a solid-liquid coupling algorithm between soil and water, it can effectively characterize the two-phase coupling effect between the landslide body and water body, and accurately simulate the induced propagation process of landslide surge waves. This invention solves the technical problem that existing numerical simulation methods cannot accurately simulate the entire process of landslide surge waves.

[0087] The following detailed description, in conjunction with the accompanying drawings, provides a specific implementation scheme for a meshless simulation method, apparatus, and medium for calculating landslide surge waves, which is part of this invention.

[0088] <Example>

[0089] like Figure 1 As shown, the meshless simulation method, device and medium for calculating landslide surge waves used in this embodiment includes the following implementation steps (step I corresponds to step 1 in the "Invention Content" section, steps II to III correspond to step 2 in the "Invention Content" section, steps IV to VI correspond to steps 3 to 5 in the "Invention Content" section, steps VIII to IX correspond to steps 6 to 7 in the "Invention Content" section, and the content already described in detail in the "Invention Content" section will not be repeated).

[0090] Step I: Determine the research scale as three dimensions and define the research area, such as... Figure 2 As shown, the region was numerically modeled using the common modeling software SolidWorks;

[0091] Step II: Select an appropriate size to mesh the numerical model, ensuring uniform distribution of mesh nodes within the region. After successful meshing, export the mesh node coordinates, assign a value of 1 to the node retrieval attribute within the landslide body, and assign a value of 2 to the node coordinate retrieval attribute within the water body. Then, assign different particle material parameters according to the landslide body parameters and water body parameters to complete the preprocessing stage. The particle parameter assignments are shown in Table 1.

[0092] Table 1. Calculation parameters for three-dimensional soil landslide surge.

[0093]

[0094]

[0095] Step III involves pairing and searching particles with different attributes. For particles with an attribute value of 1, it is determined whether there are any particles with the same attribute in contact. For particles with an attribute value of 2, it is determined whether any particles exist within the influence domain of their smooth kernel function. Both types of particle searches utilize a linked list retrieval method, storing all paired particle pairs across the entire computational domain. A schematic diagram of the linked list retrieval method's principle and flowchart is shown below. Figure 3 , Figure 4 As shown, a background grid is set within the computational domain, and the grids containing each particle are numbered. Grids with an attribute value of 1 have a size equal to the diameter of the DEM particles, while those with an attribute value of 2 have a size equal to the kernel function radius. After processing using this method, under 3D conditions, it is only necessary to search for the presence of potentially interacting particles in the 26 grids near the target grid, and then further search for whether particles in the vicinity actually interact with the target element.

[0096] Step IV: Filter the particle pairs whose attribute values ​​are all 1, and calculate the internal forces of the soil particles. The calculation process is based on formulas (4) to (9). Iterate and update the resultant internal forces of the DEM particles.

[0097] Step V: For particle pairs with filter attributes of 2, perform internal force calculations in the water. The calculation process is based on formulas (10) to (14), and the resultant internal force of the SPH particles is updated by iterating through the formulas.

[0098] Step VI: Filter the particle pairs with attribute values ​​of 1 and 2 respectively, perform coupling calculation between soil and water, refer to formula (15) to formula (22) for the calculation process, store the calculated coupling force in the form of additional force, and calculate the resultant force of particles in the overall calculation domain.

[0099] Step VII involves updating the motion parameters such as acceleration, velocity, and displacement of the overall computational domain. During the above calculation process, the time step parameters of soil landslide, water surge, and coupled calculation modules are updated simultaneously, and their integration formats are all prediction-correction methods.

[0100] Step VIII: During the calculation process, according to the output time intervals and target parameters required for subsequent analysis, export a series of .dat format files until the calculation is completed.

[0101] Step IX: Import the data into post-processing software for visualization processing, such as... Figures 5 to 7 It can be seen that the accuracy of the proposed method and device can be verified by analyzing the flow regime, landslide trajectory, and wave height along the path. Among these, Figure 5 The diagram shows the simulation results of the flow regime and landslide contour in the embodiments of the present invention. Figure 6 , Figure 7 The diagram shows the changes in surge height at three wave height meters in two sets of implementation conditions involved in this embodiment of the invention.

[0102] It should be understood that the specific order or hierarchy of steps in the process disclosed in this invention is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the specific order or hierarchy described.

[0103] In summary, this invention proposes a meshless simulation method, device, and medium for calculating landslide surges in soil, which can accurately simulate the fluid-structure interaction between soil and water. It precisely simulates the pressure distribution at the coupling interface, solving the problem of inaccurate inversion of local water pressure and soil contour development at the coupling interface. It can reasonably simulate the pressure distribution at the coupling interface, eliminate non-physical high-pressure gaps, and accurately predict the large deformation motion of soil and the propagation process of surges. It can also accurately invert the local water impact and turbulence flow patterns. Furthermore, the initial parameters selected in this invention can be obtained through field surveys and laboratory experiments, resulting in low computational costs. This invention can provide a reliable numerical calculation method for landslide surge hazard assessment and levee design.

[0104] The present invention also provides a meshless simulation device for calculating soil landslide surge waves, which can automatically implement the above-mentioned method of the present invention. The device includes a modeling module, a preprocessing module, a soil landslide simulation module, a surge wave simulation module, a landslide surge wave coupled calculation module, a time step update module, a postprocessing module, and a control module.

[0105] The modeling module performs the steps described in step I above to accurately model the engineering area under study, determine the landslide and water body shape characteristics of the site, and determine the relevant material property parameters required for calculation.

[0106] The preprocessing module performs the steps II to III described above, discretizes the computational domain, and performs secondary corrections on irregular soil and water boundary particles.

[0107] The soil landslide simulation module performs the steps described in step IV above, calculates the forces in the unstable soil area of ​​the landslide, and selects an appropriate discrete element contact model and discrete element scale while ensuring the accuracy of the landslide simulation. The discrete element method is then used to calculate the acceleration of each area of ​​the landslide body.

[0108] The surge simulation module performs the steps described in step V above. The simulation calculation of water body and surge adopts the smooth particle dynamics method. The river water body region is discretized into a series of fluid particles, and the calculation is performed through the Navier-Stokes equations in integral form to ensure that the size of fluid particles is close to that of discrete elements.

[0109] The landslide surge coupling calculation module executes the steps described in step VI above to calculate the normal coupling force between the soil and water bodies. The calculation process is carried out with reference to the optimized fully analytical format algorithm.

[0110] The time step update module executes the steps VII to VIII described above, calculates the resultant acceleration of each particle in the discrete computational domain, updates the velocity and position within a single time step, stores the target time data, and repeats the module update process until the computation time requirement is met.

[0111] The post-processing module executes the steps described in step IX above, reads the exported data, performs visualization processing, and conducts subsequent image analysis to meet computational requirements.

[0112] The control module is communicatively connected to the modeling module, the preprocessing module, the landslide simulation module, the surge simulation module, the landslide-surge coupling calculation module, the time step update module, and the postprocessing module, and controls their operation.

[0113] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps in the above-described method for calculating soil landslide surge waves.

[0114] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-readable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The present invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, produce implementations of the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 The computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0115] The above embodiments are merely illustrative examples of the technical solutions of the present invention. The meshless simulation method, apparatus, and medium for calculating landslide surges involved in this invention are not limited to the contents described in the above embodiments, but are defined by the scope of the claims. Any modifications, additions, or equivalent substitutions made by those skilled in the art based on these embodiments are within the scope of protection claimed by the claims of this invention.

Claims

1. A meshless simulation method for calculating landslide surge waves, characterized in that: Includes the following steps, Step 1: Model the engineering area under study to determine the characteristics of soil landslides and water body shapes at the site; Step 2: Discretize the computational domain, correct irregular soil landslides and water boundary particles, and determine the relevant material property parameters required for the calculation. Step 3: Calculate the forces in the unstable soil area of ​​the landslide, select an appropriate discrete element contact model and discrete element scale, and use the discrete element method to calculate the contact forces between discrete elements of particles to obtain the acceleration of each area of ​​the landslide. Step 4: The smoothed particle dynamics method is used to simulate and calculate the entire process of water body and surge. The river water body region is discretized into a series of fluid particles to ensure that the size of the fluid particles is close to that of the discrete element. Step 5: Calculate the coupling acceleration and coupling force between the soil and water bodies based on the following formulas. In the formula: Du i / D t The coupling acceleration represents particle i, where i represents discrete particle i, j represents discrete particle j, and u i This represents the calculation of the velocity of particle i, where t is time and p is the velocity of particle i. i and p j The fluid pressures ρ for particles i and j are respectively. i Let be the density of particle i, and W be the kernel function. W is the displacement partial differential form of the kernel function. ij V represents the kernel function value at the relative positions of particles i and j. j Let μ be the volume of the particle. i and μ j The viscosity coefficients of particles i and j are respectively, r ij Let be the distance between particles i and , h be the smooth length, and g be the gravitational acceleration, with a value of -9.81 m / s². 2 γ = 7, c0 is the artificial speed of sound, ρ 0χ For the reference density of phase χ, F coupling For coupling force, m i Let Γ be the mass of particle i, and let Γ be the set of particles that are coupled with particle i. Step 6: Calculate the resultant acceleration of each particle in the discrete computational domain, update the velocity and position within a single time step, and store the target time data. Repeat the above steps until the computation time requirement is met. Step 7: Read the exported data, perform visualization processing, and conduct subsequent image analysis to meet the calculation requirements.

2. The meshless simulation method for calculating landslide surge waves according to claim 1, characterized in that: Step 3 specifically includes the following sub-steps: Step 3.1: Set the series of discrete nodes located within the soil region as Discrete Element Method (DEM) particles with a radius of 0.5 times the distance between discrete nodes. Obtain the macroscopic soil deformation process by calculating the cumulative microscopic displacement of the particles under stress. Step 3.2, the formula for calculating the contact force between discrete particle elements is shown below: F n =k n d n n+F ndamp (4) F t =max[(F t ) T-Δt +k t δ t +F tdamp ,μ||F n ||] (5) In the formula: F n For normal contact force, F t For tangential contact force, δ n δ is the normal overlap between particles, n is the direction of the line connecting the centers of the two particles, and δ is the normal overlap between particles. t δ represents the tangential overlap between particles. t F represents the relative displacement between contact positions within a single time step. ndamp With F tdamp These represent the normal and tangential damping forces, respectively. t ) t-Δt The tangential contact force at the particle contact surface at the end of the previous time step is given by k, μ is the coefficient of kinetic friction between the particles, and the smaller of the two coefficients is taken. n With k t These are the normal and tangential stiffnesses of the contact interface, respectively, and the Hertz-Mindlin contact model is used for their calculation. In the formula: G*=0.5(G i +G j ), R*=2R i R j / (R i +R j ), v * =0.5(v) i +v j ), where i and j represent particle i and particle j respectively; G is the shear modulus, G i and G j Let i and j represent the shear modulus of particles i and j, respectively, and R be the particle radius. i and R j Let i and j represent the particle radii, respectively, and v be Poisson's ratio. i and v j Let s represent the Poisson's ratios of particles i and j, respectively. overlap This represents the contact overlap distance between particle i and particle j; Step 3.3: The resultant force on a single particle in contact is calculated using the following formula: In the formula: F n total，i F is the net normal force acting on a single particle in contact. t total，i F is the net tangential force acting on a single particle in contact. n，ij Let F be the normal contact force between particle i and particle ? t，ij Let N be the tangential contact force between particle i and particle j, and let N represent the set of particles in contact with particle i.

3. The meshless simulation method for calculating landslide surge waves according to claim 1, characterized in that: Step 4 specifically includes the following sub-steps: Step 4.1: The water body discretization method selected is the Smoothed Particle Hydrodynamics (SPH) method. A series of discrete nodes located in the water body region are set as SPH particles with a radius equal to the distance between discrete nodes. The macroscopic water body evolution process is obtained by calculating the cumulative microscopic displacement of the particles under force. Step 4.2, the force calculation for fluid particles refers to the following formula: Where: Dρ i / D t Du is the density gradient of particle i. i / D t Let ρ be the coupling acceleration of particle i. i and ρ j The densities of particles i and j are given by denoted as i and j, respectively, where t is time and u is the density of particles i and j. j and u i These are the velocity vectors of particles j and i, respectively. W is the displacement partial differential form of the kernel function. ij The kernel function values ​​represent the relative positions of particles i and j, m. j Let p be the mass of particle j. i and p j Let be the fluid pressures of particles i and j, respectively, and c0 be the artificial speed of sound. Since the density gradient of SPH particles must be less than 1%, the value of c0 must be no less than 10 times the maximum velocity of the flow field. i and r j These are the displacement vectors of particles i and j, respectively, and ρ0 is the reference density (the density of water is taken as 1000 kg / m³ at 20℃ and one standard atmosphere). 3 ), u ij Let be the velocity vector difference between particles i and j, δ be the density diffusion term, μ be the viscosity coefficient, γ = 7, and g be the gravitational acceleration, taken as -9.81 m / s². 2 W is the kernel function. ij =W(r) i -r j ,h), in the format: In the formula: q=||r i -r j || / h,α dim It is a parameter related to the calculation dimension; in the two-dimensional case, it is taken as 7 / (4πh). 2 Under three-dimensional working conditions, take 21 / (16πh) 3 The smooth length h is usually taken as 1.5 to 2 times the initial particle spacing in two-dimensional cases and as 1.5 times the particle spacing in three-dimensional cases to ensure the accuracy of the calculation. Step 4.3, the internal forces acting on a single-fluid particle are calculated using the following formula: In the formula: u i This is the calculated velocity vector of a single particle.

4. The meshless simulation method for calculating landslide surge waves according to claim 1, characterized in that: Step 5 specifically includes the following sub-steps: Step 5.1: Perform solid and liquid phase particle retrieval at the coupling interface, modify the properties of solid phase particles within the influence domain of fluid particles, and assign them the characteristics of fluid SPH particles of the same density. Step 5.2: Calculate the coupling force between soil and water. The normal and tangential forces between particles are calculated according to different analytical formats. The calculation of the normal force refers to the fully analytical format algorithm. For specific calculation, see formulas (1) to (3). Step 5.3: The formula for calculating tangential force is a non-analytical empirical format. The specific calculation formula is as follows: In the formula: i and k represent fluid particle i and soil particle k, respectively. F is the tangential force acting on particle k. i d V is the tangential force acting on particle i. i and V j Let m be the volume of particles i and j, respectively. i Let p be the mass of fluid particle i. i Let W be the fluid particle pressure, W be the kernel function, and ε be the fluid particle pressure. k Let u be the local porosity of particle k. k Let k be the average velocity of particle k. W represents the average velocity of the fluid particles surrounding particle k after interpolation, where Ω and Ω' both represent the set of particles interacting with the target particle. ik and W jk Let i and k represent the kernel function values ​​at the relative positions of particles i, k and j, k, respectively, and η be the interphase momentum transfer coefficient, which is related to the local average porosity and relative velocity. Where: μ f The viscosity coefficient of the fluid (at 20℃ and one standard atmosphere, water is taken as 1.0 × 10⁻⁶) -3 Pa·s), R k Where ρ is the particle radius of the DEM. f For fluid density (under standard operating conditions, water is taken as 1.0 × 10⁻⁶),... 3 kg / m 3 ), C d The drag coefficient is shown below; further calculation details are as follows: Where: ε k Let ε be the local porosity of particle k. i Let W be the local porosity of particle i. ik V represents the kernel function value at the relative positions of particles i and k. k Let m be the volume of particle k. i R is the mass of fluid particle i. k Re represents the particle radius of the DEM. k Let be the Reynolds number of the flow field near the particle.

5. The meshless simulation method for calculating landslide surge waves according to claim 1, characterized in that: Step 6 specifically includes the following sub-steps: Step 6.1: Update the prediction step and correction step within a single time step: In the formula: Let be the velocity vector of particle i after the (n+1 / 2)th step. Let Δt be the velocity vector of particle i after step (n), and Δt be the time step. Let i be the acceleration vector of particle i after step (n). Let be the angular velocity vector of particle i after the (n+1 / 2)th step. Let be the angular velocity vector of particle i after step (n). Let be the angular acceleration vector of particle i after step (n). Let be the turning angle of particle i after the (n+1 / 2)th step. Let i be the turning angle of particle i after step (n). Let i be the density of particle i after the (n+1 / 2)th step. Let be the density of particle i after step (n). Let be the density gradient of particle i after step (n). Let r be the displacement vector of particle i after the (n+1 / 2)th step. in Let be the displacement vector of particle i after step (n). Let i be the velocity vector of particle i after step (n). The fluid pressure after step (n+1 / 2) is... Let f be the density after the (n+1 / 2)th step, and f be the scaling factor. Formula (23) is a simplified expression of the state equation. After the prediction step, parameters such as velocity u, angular velocity ω, angular displacement θ, density ρ, linear displacement r, and fluid pressure p can be obtained for the (n+1 / 2)th step. These parameters are used to calculate the continuity equation and momentum equation of SPH and DEM to obtain the acceleration a for the (n+1 / 2)th step. i n+1 / 2 Density gradient (Dρ / Dt) i n+1 / 2 These parameters are used to prepare for the next step of correction. Step 6.2, Correction Step: In the formula: Let be the velocity vector of particle i after the (n+1 / 2)th step. Let Δt be the velocity vector of particle i after step (n), and Δt be the time step. Let be the acceleration vector of particle i after the (n+1 / 2)th step. Let be the angular velocity vector of particle i after the (n+1 / 2)th step. Let be the angular velocity vector of particle i after step (n). Let be the angular acceleration vector of particle i after the (n+1 / 2)th step. Let be the turning angle of particle i after the (n+1 / 2)th step. Let i be the turning angle of particle i after step (n). Let i be the density of particle i after the (n+1 / 2)th step. Let be the density of particle i after step (n). Let be the density gradient of particle i after the (n+1 / 2)th step. Let r be the displacement vector of particle i after the (n+1 / 2)th step. i n Let be the displacement vector of particle i after step (n); Step 6.3, Parameter Update: p n+1 =f(ρ n+1 ) (27) In the formula: Let be the velocity vector of particle i after step (n+1). Let be the velocity vector of particle i after the (n+1 / 2)th step. Let i be the velocity vector of particle i after step (n). Let be the angular velocity vector of particle i after the (n+1)th step. Let be the angular velocity vector of particle i after the (n+1 / 2)th step. Let be the angular velocity vector of particle i after step (n). Let be the turning angle of particle i after the (n+1)th step. Let be the turning angle of particle i after the (n+1 / 2)th step. Let i be the turning angle of particle i after step (n). Let be the density of particle i after step (n+1). Let i be the density of particle i after the (n+1 / 2)th step. Let r be the density of particle i after step (n). i n+1 Let be the displacement vector of particle i after the (n+1)th step. For a particle; the displacement vector after the (n+1 / 2)th step. p is the displacement vector of particle i after step (n); n+1 ρ is the fluid pressure after step (n+1). n+1 Let f be the density after step (n+1), and f be the scaling factor. In the DEM-SPH framework, the time steps of the two modules are kept consistent and determined according to the following formula (28): In the formula: Δt is the duration of a single step, Δt DEM Δt represents the single-step duration of DEM particles. SPH The single-step duration of SPH particles, in m i Let i be the mass of the discrete element i, and k be the mass of the particle. ni h is the maximum contact stiffness of discrete element i. i Where is the smooth length of the SPH particle, v is the kinematic viscosity of the fluid, and a i Here, c0 is the particle acceleration, and u is the artificial speed of sound. max The maximum flow velocity in the flow field is denoted as .

6. A meshless simulation device for calculating landslide surge waves, characterized in that: Includes the following modules, The modeling module is used to model the engineering area under study and determine the soil landslide and water body shape characteristics of the site. The preprocessing module is used to discretize the computational domain, correct irregular soil landslides and water boundary particles, and determine the relevant material property parameters required for the calculation. The soil landslide simulation module is used to calculate the stress in the unstable soil area of ​​a landslide. By selecting an appropriate discrete element contact model and discrete element scale, the discrete element method is used to calculate the contact force between discrete elements of particles and obtain the acceleration of each region of the landslide. The surge simulation module is used to simulate and calculate the entire process of water body and surge using the smooth particle dynamics method. The river water body region is discretized into a series of fluid particles to ensure that the size of the fluid particles is close to that of the discrete element. The landslide surge coupling calculation module is used to calculate the coupling acceleration and coupling force between soil and water based on the following formulas. In the formula: Du i / D t The coupling acceleration represents particle i, where i represents discrete particle i, j represents discrete particle j, and u i This represents the calculation of the velocity of particle i, where t is time and p is the velocity of particle i. i and p j The fluid pressures ρ for particles i and j are respectively. i Let be the density of particle i, and W be the kernel function. W is the displacement partial differential form of the kernel function. ij V represents the kernel function value at the relative positions of particles i and j. j Let μ be the volume of the particle. i and μ j The viscosity coefficients of particles i and j are respectively, r ij Let be the distance between particles i and , h be the smooth length, and g be the gravitational acceleration, with a value of -9.81 m / s². 2 γ = 7, c0 is the artificial speed of sound, ρ 0χ For the reference density of phase χ, F coupling For coupling force, m i Let Γ be the mass of particle i, and let Γ be the set of particles that are coupled with particle i. The time step update module is used to calculate the resultant acceleration of each particle in the discrete computation domain, update the velocity and position within a single time step, and store the target time data until the computation time requirement is met. The post-processing module is used to read the exported data, perform visualization processing, and conduct subsequent image analysis to meet computational requirements.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the steps in any one of the meshless simulation methods for calculating soil landslide surges as described in any one of claims 1 to 5.

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