Meshless simulation method and device for calculating soil landslide surge and medium

Abstract

The invention belongs to the technical field of dike geological disaster simulation, particularly relates to a meshless simulation method and a meshless simulation device for calculating soil landslide surge and a medium, solves the problem of inaccurate inversion of local water pressure of a coupling interface and a soil contour development process, can effectively represent a biphase coupling effect between a landslide body and a water body, and improves the calculation accuracy of the soil landslide surge. According to the method, the pressure distribution of a coupling interface can be reasonably simulated, non-physical high-pressure gaps can be eliminated, the large-deformation movement process and the surge propagation process of a soil body can be accurately predicted, the local water body impact turnup flow state can also be accurately inverted, and a visual analysis material is provided. The meshless simulation device for calculating the soil body landslide surge can accurately simulate various working conditions such as high-speed and low-speed soil body landslide surge, is applied to related research and analysis in typical sections and areas, and provides guidance for clarifying the evolution law of the soil body landslide surge and preventing and controlling surge disasters. The device can accurately simulate the whole process of soil landslide surge.

Description

Technical Field:

[0001] The present invention belongs to the technical field of levee geological disaster simulation, and particularly relates to a meshless simulation method, device and medium for calculating landslide-induced waves of soil masses. Background Art:

[0002] In the construction of levees and the early warning analysis of geological disasters, the secondary disaster of landslide-induced waves is a very important research content. The process of the instability and failure of the soil slope adjacent to water resulting in landslides and the landslide body entering the water and inducing waves involves complex fluid-solid coupling effects. Exploring this mechanism is of great significance for effectively inverse-analyzing the evolution process of landslide-induced waves and establishing a geological disaster early warning system.

[0003] In existing numerical simulation studies, restricted by the large deformation characteristics of soil masses and water bodies and the different governing equations between the two, there are certain technical difficulties in carrying out relevant multiphase coupling calculations. The existing coupling algorithms are unreliable for inverse-analyzing the local water pressure and the development process of the soil profile. There are large errors in the wave amplitude of the induced wave evolution and the development trajectory of the soil profile obtained. Therefore, the existing numerical simulation methods cannot accurately simulate the whole process of landslide-induced waves of soil masses. Summary of the Invention:

[0004] The present invention is proposed to solve the above deficiencies, and aims to provide a meshless simulation method, device and medium for calculating landslide-induced waves of soil masses, which can solve the technical problem that the existing numerical simulation methods cannot accurately simulate the whole process of landslide-induced waves of soil masses.

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

[0006] The present invention designs a meshless simulation method for calculating landslide-induced waves of soil masses, including 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 calculation area, and perform secondary correction on the particles at the irregular soil mass and water body boundaries to determine the relevant material property parameters required for the calculation;

[0009] Step 3: Calculate the forces acting on the landslide-instability soil mass area. On the premise of ensuring the landslide simulation accuracy, select a suitable discrete element contact model and discrete element scale, and use the discrete element method for calculation to obtain the accelerations of each area of the landslide body;

[0010] Step 4: The simulation calculation of the water body and the induced waves adopts the smoothed particle hydrodynamics method. The river water body area is discretized into a series of fluid particles, and the calculation is carried out through the integral form of the Navier-Stokes equation, ensuring that the fluid particle size is close to that of the discrete element;

[0011] Step 5: Calculate the normal coupling force between the soil and water bodies. The calculation process is carried out with reference to the optimized full analytical format algorithm, and the normal coupling acceleration is calculated based on the following formula:

[0012]

[0013] In the formula: Du i / D t represents the coupling acceleration, i represents the discrete particle i, j represents the discrete particle j, u i represents the velocity of the calculation particle i, t is the time, p i and p j are the fluid pressures of particles i and j respectively (the calculation of the soil particle pressure in the coupling calculation process refers to formula (3)), ρ i is the density of particle i, W is the kernel function, is the displacement partial differential form of the kernel function, W ij represents the value of the kernel function at the relative position of particles i and j, V j is the volume of particle j, μ i and μ j are the viscosity coefficients of particles i and j respectively, r ij is the distance between particles i and j, h is the smoothing length, g is the gravitational acceleration, with a value of -9.81 m / s 2 , γ = 7, c 0 is the artificial sound speed, ρ 0χ is the reference density of phase χ, F coupling is the coupling force, m i is the mass of particle i, Γ is the set of particles that have a coupling interaction with particle i; the calculation process of the tangential coupling force between the 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 data at the target time. Repeat steps 1 to 3 until the calculation duration requirement is met.

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

[0016] Preferably, a meshless simulation method for calculating soil landslide surges provided by the present invention may also have the following characteristics: In step 2, the discretization of the soil landslide and water body can be assisted by existing preprocessing tools, aiming to generate a series of coordinate nodes that are close in distance and evenly distributed to represent the actual contours of the soil landslide and water body, and provide initial conditions for subsequent calculations.

[0017] Preferably, a meshless simulation method for calculating soil landslide surge waves provided by the present invention may further have the following characteristics: In step 3, it specifically includes the following sub-steps:

[0018] Step 3.1: A series of discrete nodes located within the soil region are set as discrete element (Discrete Element Method, DEM) particles, with a radius of 0.5 times the distance between discrete nodes. By calculating the cumulative mesoscopic displacement of particle forces, the macroscopic soil deformation process is obtained;

[0019] The formula for the contact force between particle discrete elements is as follows:

[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 || (Equation 5) In the formula: F n is the normal contact force, F t is the tangential contact force, δ n is the normal overlap amount between particles, n is the direction of the line connecting the centers of the two particles, δ t is the tangential overlap amount between particles, δ t is the relative displacement between contact positions within a single time step, F ndamp and F tdamp respectively represent the normal and tangential damping forces, (F t ) T-Δt is the tangential contact force on the particle contact surface at the end of the previous time step, μ is the dynamic friction coefficient between particles, taking the smaller value of the two dynamic friction coefficients, k n and k t are the normal stiffness and tangential stiffness of the contact interface respectively, and the Hertz-Mindlin contact model is selected for its 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 represent the shear moduli of particle i and j respectively, R is the particle radius, R i and R j represent the particle radii of particle i and j respectively, v is the Poisson's ratio, v i and v j represent the Poisson's ratios of particle i and j respectively, s overlap represents the contact overlap distance between particle i and particle j;

[0024] Step 3.3. The calculation of the resultant contact force on a single particle refers to the following formula:

[0025]

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

[0027] Preferably, a meshless simulation method for calculating soil landslide surges provided by the present invention may further have the following characteristics: In step 4, it specifically includes the following sub-steps:

[0028] Step 4.1. The water body discretization method selects the Smoothed Particle Hydrodynamics (SPH) method. A series of discrete nodes located in the water body area are set as SPH particles, and the radius is the discrete node spacing. By calculating the cumulative mesoscopic displacement of particle forces, the macroscopic water body evolution process is obtained;

[0029] Step 4.2. The calculation of the fluid particle force refers to the following formula:

[0030]

[0031] In the formula: Dρ i / D t is the density gradient of particle i, Du i / D t is the coupling acceleration of particle i, ρ i and ρ j are the densities of particle i and j respectively, t is the time, u j and u i are the velocity vectors of particle j and i respectively, It is the displacement partial differential form of the kernel function, W ij represents the value of the kernel function at the relative positions of particles i and j, m j is the mass of particle j, p i and p j are the fluid pressures of particles i and j respectively, c 0 is the artificial sound speed. To ensure the weak compressibility assumption of the fluid, the density change gradient of SPH particles needs to be less than 1%. Therefore, c 0 should be no less than 10 times the maximum velocity of the flow field. r i and r j are the displacement vectors of particles i and j respectively, ρ 0 is the reference density (at 20°C and one standard atmosphere, the density of water is taken as 1000 kg / m 3 ), u ij is the velocity vector difference between particles i and j, δ is the density diffusion term, μ is the viscosity coefficient, γ = 7, g is the acceleration due to gravity, taken as -9.81 m / s 2 , W is the kernel function, W ij = W(r i - r j , h), and the format is:

[0032]

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

[0034] Step 4.3. The internal force on a single-fluid particle is calculated with reference to the following formula:

[0035]

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

[0037] Preferably, a meshless simulation method for calculating soil landslide surges provided by the present invention may further have the following characteristics: In step 5, it specifically includes the following sub-steps:

[0038] Step 5.1. Perform solid and liquid phase particle retrieval at the coupling interface, correct the attributes of solid particles within the influence domain of fluid particles, and endow them with the characteristics of SPH particles with the same density fluid;

[0039] Step 5.2: Calculate the coupling force between the 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 full analytical format algorithm, and the specific calculation can be seen in Formulas (1) to (3).

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

[0041]

[0042] In the formula: i and k respectively represent fluid particle i and soil particle k. is the tangential force received by particle k. is the tangential force received by particle i, V i and V j are the volumes of particles i and j respectively, m i is the mass of fluid particle i, p i is the pressure of the fluid particle, W is the kernel function, εk is the local porosity of particle k, uk is the average velocity of particle k. is the average velocity of the fluid particles around particle k after interpolation. Both Ω and Ω’ represent the set of particles acting on the target particle. W ik and W jk represent the values of the kernel function at the relative positions of particles i, k and j, k respectively. η is the interfacial momentum transfer coefficient, and this parameter is related to the local average porosity and relative velocity:

[0043]

[0044] In the formula: μ f is the fluid viscosity coefficient (at 20°C and one standard atmospheric pressure, for water it is 1.0×10 -3 Pa·s), R k is the radius of the DEM particle, ρ f is the fluid density (under standard conditions, for water it is 1.0×10 3 kg / m 3 ), C d is the drag coefficient. More calculation details are as follows:

[0045]

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

[0047] Preferably, a meshless simulation method for calculating soil landslide surge provided by the present invention may further have the following characteristics: In step 6, it 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: is the velocity vector of particle i after the (n + 1 / 2) step, is the velocity vector of particle i after the nth step, Δt is the time step, is the acceleration vector of particle i after the nth step, is the angular velocity vector of particle i after the (n + 1 / 2) step, is the angular velocity vector of particle i after the nth step, is the angular acceleration vector of particle i after the nth step, is the rotation angle of particle i after the (n + 1 / 2) step, is the rotation angle of particle i after the nth step, is the density of particle i after the (n + 1 / 2) step, is the density of particle i after the nth step, is the density change gradient of particle i after the nth step, is the displacement vector of particle i after the (n + 1 / 2) step, r i n is the displacement vector of particle i after the nth step, is the velocity vector of particle i after the nth step, is the fluid pressure after the (n + 1 / 2) step, is the density after the (n + 1 / 2) step, f is a proportionality coefficient, and the calculation format refers to formula (12);

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

[0052] Step 6.2, Correction Step:

[0053]

[0054] Where: is the velocity vector of particle i after the (n + 1 / 2)-th step, is the velocity vector of particle i after the n-th step, and Δt is the time step, is the acceleration vector of particle i after the (n + 1 / 2)-th step, is the angular velocity vector of particle i after the (n + 1 / 2)-th step, is the angular velocity vector of particle i after the n-th step, is the angular acceleration vector of particle i after the (n + 1 / 2)-th step, is the rotation angle of particle i after the (n + 1 / 2)-th step, is the rotation angle of particle i after the n-th step, is the density of particle i after the (n + 1 / 2)-th step, is the density of particle i after the n-th step, is the density change gradient of particle i after the (n + 1 / 2)-th step, is the displacement vector of particle i after the (n + 1 / 2)-th step, r i 2 is the displacement vector of particle i after the n-th step;

[0055] Step 6.3, Parameter Update:

[0056]

[0057] p n+1 = f(ρ n+1 ) In equation (27): is the velocity vector of particle i after the (n + 1)-th step, is the velocity vector of particle i after the (n + 1 / 2)-th step, is the velocity vector of particle i after the n-th step, is the angular velocity vector of particle i after the (n + 1)-th step, is the angular velocity vector of particle i after the (n + 1 / 2)-th step, is the angular velocity vector of particle i after the n-th step, is the rotation angle of particle i after the (n + 1)-th step, is the rotation angle of particle i after the (n + 1 / 2)-th step, is the rotation angle of particle i after the n-th step, is the density of particle i after the (n + 1)-th step, is the density of particle i after the (n + 1 / 2)-th step, is the density of particle i after the n-th step, r i n+1 is the displacement vector of particle i after the (n + 1)-th step, is the displacement vector of particle i after the (n + 1 / 2)-th step, r i n is the displacement vector of particle i after the n-th step; p n+1 is the fluid pressure after the (n + 1)-th step, ρ n+1 is the density after the (n + 1)-th step, f is a proportionality coefficient, and the calculation format refers to 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] where: Δt is the duration of a single step, Δt DEM is the duration of a single step of the DEM particles, Δt SPH is the duration of a single step of the SPH particles, m i is the mass of the granular discrete element i, k ni is the maximum contact stiffness of the discrete element i, h i is the smoothing length of the SPH particle, v is the kinematic viscosity coefficient of the fluid, a i is the particle acceleration, c 0 is the artificial sound speed, u max is the maximum flow velocity of the flow field.

[0061] Preferably, a meshless simulation method for calculating soil landslide surge provided by the present invention may further have the following characteristics: In step 6, the calculations of the soil and water frameworks 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 frameworks 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, and the drag force calculation is based on a non-analytical empirical formula.

[0062] Preferably, a meshless simulation method for calculating soil landslide surge provided by the present invention may further have the following characteristics: In step 7, the processing of the exported data can be realized by means of existing open-source post-processing software, and subsequent analysis and research are carried out in specific local, planar, three-dimensional, animation and other forms to visualize the model update.

[0063] The present invention also designs a meshless simulation device for calculating soil landslide surge, which can automatically implement the above <method>, including:

[0064] A modeling module that precisely models the engineering area under study to determine the landslide and water body shape characteristics of the site;

[0065] A preprocessing module that discretizes the calculation area, makes secondary corrections for irregular soil and water body boundary particles, and determines the relevant material property parameters required for the calculation;

[0066] A soil landslide simulation module that calculates the forces acting on the unstable soil area of the landslide. On the premise of ensuring the accuracy of the landslide simulation, it selects an appropriate discrete element contact model and discrete element scale, and uses the discrete element method for calculation to obtain the accelerations of each area of the landslide body;

[0067] A surging wave simulation module that uses the smoothed particle hydrodynamics method for the simulation calculation of water bodies and surging waves. The river channel water body area is discretized into a series of fluid particles and calculated through the integral form of the Navier-Stokes equation to ensure that the fluid particle size is close to that of the discrete element;

[0068] A landslide-surging wave coupling calculation module that calculates the normal coupling force between the soil and the water body. The calculation process is carried out with reference to the optimized full analytical format algorithm, and the normal coupling acceleration is calculated based on the following formula:

[0069]

[0070] Where: Du i / D t represents the coupling acceleration of particle i, i represents discrete particle i, j represents discrete particle j, u i represents the velocity of calculation particle i, t is time, p i and p j are the fluid pressures of particles i and j respectively, ρ i is the density of particle i, W is the kernel function, is the displacement partial differential form of the kernel function, W ij represents the value of the kernel function at the relative position of particles i and j, V j is the volume of particle j, μ i and μ j are the viscosity coefficients of particles i and j respectively, r ij is the distance between particles i and j, h is the smoothing length, g is the acceleration due to gravity, with a value of -9.81 m / s 2 , γ = 7, c 0 is the artificial sound speed, ρ 0χ is the reference density of phase χ, F coupling is the coupling force, m i is the mass of particle i, and Γ is the set of particles that couple with particle i;

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

[0072] The post-processing module reads the exported data, performs visualization processing, and conducts subsequent image analysis that meets the calculation requirements.

[0073] The control module is communicatively connected to the modeling module, the pre-processing module, the soil landslide simulation module, the surging wave simulation module, the landslide surging wave coupling calculation module, the time step update module, and the post-processing module, and controls their operations.

[0074] Preferably, a meshless simulation device for calculating soil landslide surging waves provided by the present invention may further have the following characteristics: generalize and model the actual project, divide the key research area, generate a numerical model in STL format or DXF format, import it into the pre-processing software, perform mesh division, and generate node coordinates to import into the subsequent calculation module.

[0075] Advantages of the present invention:

[0076] The meshless simulation method, device, and medium for calculating soil landslide surging waves provided by the present invention solve the problems of inaccurate inversion of the local water pressure at the coupling interface and the development process of the soil contour, can effectively characterize the two-phase coupling effect between the landslide body and the water body, and accurately simulate the induced propagation process of soil landslide surging 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 body and the surging wave propagation process, can also accurately invert the local water impact and overturning flow pattern, and provide visualization analysis materials. The meshless simulation device for calculating soil landslide surging waves provided by the present invention can accurately simulate various working conditions such as fast and slow soil landslide surging waves, and is applied to relevant research and analysis in typical cross-sections and regions, providing guidance for clarifying the evolution law of soil landslide surging waves and the prevention and control of surging wave disasters. Therefore, the present invention can accurately simulate the whole process of soil landslide surging waves. Description of the drawings:

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

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

[0079] Figure 3 It is a schematic diagram of a particle retrieval method involved in an embodiment of the present invention.

[0080] Figure 4 It is a flowchart of particle contact retrieval involved in an embodiment of the present invention.

[0081] Figure 5 This is the simulation result diagram of the water body and landslide body profiles involved in the embodiments of the present invention.

[0082] Figure 6 This is the result diagram of the surging wave height change at the wave gauge in working condition 1 involved in the embodiments of the present invention.

[0083] Figure 7 This is the result diagram of the surging wave height change at the wave gauge in working condition 2 involved in the embodiments of the present invention. Specific implementation manners:

[0084] To make the technical problems solved by the present invention, the technical solutions adopted and the achieved technical effects clearer, the technical solutions of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only the parts related to the present invention are shown in the drawings, rather than all of them.

[0085] Due to their meshless-dependent properties, the Discrete Element Method (DEM) and the Smoothed Particle Hydrodynamics (SPH) method are applicable to the study of the mechanical properties of soil and water bodies. The DEM-SPH coupling framework has also been gradually applied to the field of landslide-induced surging wave simulation.

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

[0087] The following will describe in detail the specific implementation schemes of a meshless simulation method, device, and medium for calculating landslide-induced surging waves in soil according to the present invention with reference to the accompanying drawings.

[0088] <Embodiment>

[0089] As Figure 1 shown, a meshless simulation method, device, and medium for calculating landslide-induced surging waves in soil adopted in this embodiment includes the following implementation steps (the following step I corresponds to step 1 in the "Summary of the Invention" part, steps II - III correspond to step 2 in the "Summary of the Invention" part, steps IV - VI correspond to steps 3 - 5 in the "Summary of the Invention" part, steps VIII - IX correspond to steps 6 - 7 in the "Summary of the Invention" part, and the content that has been described in detail in the "Summary of the Invention" part will not be repeated).

[0090] Step I: Determine that the research scale is three-dimensional and determine the research area, such as Figure 2 shown, and use the common modeling software SolidWorks to numerically model the area;

[0091] Step II: Select appropriate sizes to mesh the numerical model, ensure that the grid nodes are evenly distributed within the area, export the grid node coordinates after successful meshing, assign the retrieval attribute value of 1 to the nodes within the landslide body, assign the retrieval attribute value of 2 to the node coordinates within the water body, and 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 Values of calculation parameters for three-dimensional soil landslide surge

[0093]

[0094]

[0095] Step III: Pairwise retrieve particles with different attributes. For particles with an attribute assignment of 1, determine whether there are particles with the same attribute in contact. For particles with an attribute assignment of 2, determine whether there are particles within the influence domain of its smoothing kernel function. The linked list retrieval method is selected for both types of particle retrieval methods to store all paired particle pairs within the entire computational domain. The principle and process schematic diagram of the linked list retrieval method are as Figure 3 、 Figure 4 shown. Set a background grid within the computational domain and number the grids where each particle is located. The grid size for particles with an attribute assignment of 1 is the diameter of the DEM particles, and the grid size for particles with an attribute assignment of 2 is the radius of the kernel function. After processing with this method, under three-dimensional working conditions, only need to retrieve whether there are potentially acting particles in the 26 grids near the target grid, and then further retrieve whether there is an actual interaction between the particles within the nearby range and the target element.

[0096] Step IV: Filter out particle pairs with both attribute assignments of 1 and perform the calculation of the internal force of soil particles. The calculation process refers to Formulas (4) to (9), and traverse and update the resultant internal force of the DEM particles.

[0097] Step V: Filter out particle pairs with both attribute assignments of 2 and perform the calculation of the internal force within the water body. The calculation process refers to Formulas (10) to (14), and traverse and update the resultant internal force of the SPH particles.

[0098] Step VI: Filter out particle pairs with attribute assignments of 1 and 2 respectively and perform the coupling calculation between the soil body and the water body. The calculation process refers to Formulas (15) to (22), store the calculated coupling force in the form of an additional force, and calculate the resultant force of the particles within the entire computational domain.

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

[0100] Step VIII, according to the output time interval and target parameters required to satisfy subsequent calculations, during the calculation process, export a series of.dat format files until the calculation ends.

[0101] Step IX, import into the post-processing software for visualization processing, such as Figures 5 to 7 It can be seen that by analyzing the flow pattern, the landslide body trajectory, and the numerical values of the surge height along the way, the accuracy of the proposed method and device can be verified. Among them, Figure 5 This is the simulation result diagram of the flow pattern and the landslide body contour involved in the embodiment of the present invention. Figure 6 and Figure 7 This is the result diagram of the change in the surge height at three wave gauges in two sets of implementation conditions involved in the embodiment of the present invention.

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

[0103] In summary, the present invention proposes a meshless simulation method, device, and medium for calculating soil landslide surges that can accurately simulate the fluid-structure interaction between soil and water, accurately simulate the pressure distribution at the coupling interface, solve the problem of inaccurate inversion of the local water pressure and the soil contour development process at the coupling interface, can reasonably simulate the pressure distribution at the coupling interface, eliminate non-physical high-pressure gaps, can accurately predict the large deformation movement process of the soil and the surge propagation process, and can also accurately invert the local water impact and rolling flow pattern; and the initial parameters selected in the present invention can all be obtained through on-site surveys and laboratory experiments, and the calculation cost is relatively low, which can provide a reliable numerical calculation means for soil landslide surge disaster assessment and levee design.

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

[0105] The modeling module performs the content 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 the calculation.

[0106] The preprocessing module performs the content described in steps II to III above to discretize the calculation area and perform secondary correction on the particles at the irregular soil and water body boundaries.

[0107] The soil landslide simulation module performs the content described in step IV above to calculate the forces acting on the landslide-instability soil area. On 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 for calculation to obtain the accelerations of each area of the landslide body.

[0108] The surging wave simulation module performs the content described in step V above. The simulation calculation of the water body and surging waves uses the smoothed particle hydrodynamics method. The river water body area is discretized into a series of fluid particles and calculated through the integral form of the Navier-Stokes equation to ensure that the fluid particle size is close to that of the discrete element.

[0109] The landslide-surging wave coupling calculation module performs the content described in step VI above to calculate the normal coupling force between the soil and water bodies, and the calculation process is carried out with reference to the optimized full analytical format algorithm.

[0110] The time step update module performs the content described in steps VII to VIII above to calculate the combined acceleration of each particle in the discrete calculation domain, perform the velocity and position update within a single time step, store the data at the target time, and repeat the above module update process until the calculation duration requirement is met.

[0111] The post-processing module performs the content described in step IX above to read and export the data, perform visualization processing, and perform subsequent image analysis that meets the calculation requirements.

[0112] The control module is communicatively connected to the modeling module, the preprocessing module, the soil landslide simulation module, the surging wave simulation module, the landslide-surging wave coupling calculation module, the time step update module, and the post-processing module to control their operations.

[0113] The present invention also provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the steps in the above-mentioned meshless simulation method for calculating soil landslides and surging waves are implemented.

[0114] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in the flow Figure 1 one flow or multiple flows and / or blocks Figure 1 These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions specified in the flow Figure 1 one flow or multiple flows and / or blocks Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in the flow Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0115] The above embodiments are merely illustrative examples of the technical solutions of the present invention. A meshless simulation method, device, and medium for calculating soil landslide surge waves involved in the present invention are not limited to the content described in the above embodiments, but are subject to the scope defined by the claims. Any modifications, supplements, or equivalent replacements made by those skilled in the art of the present invention based on this embodiment are within the scope protected by the claims of the present invention.

Claims

1. A meshless simulation method for calculating soil landslide surge, characterized by: The following steps are included: Step 1: Model the project area under study and determine the soil landslide and water body shape characteristics of the site; Step 2: Discretize the calculation area, make corrections for irregular soil landslides and water boundary particles, and determine the relevant material characteristic parameters required for calculation; Step 3: Calculate the stress on the unstable soil area of ​​the landslide, select a suitable discrete element contact model and discrete element scale, use the discrete element method to calculate the contact force between the particle discrete elements, and obtain the acceleration of each area of ​​the landslide body; Step 4: Use the smooth particle dynamics method to simulate the whole process of water body and surge. The river water area is discretized into a series of fluid particles to ensure that the size of the fluid particles is close to the discrete element. Step 5: Calculate the coupling acceleration and coupling force between soil and water based on the following formula: Where: Du i / D t represents the coupled acceleration of particle i, i represents discrete particle i, j represents discrete particle j, u i represents the speed of particle i, t is the time, p i and p j are the fluid pressures of particles i and j, respectively, and ρ i is the density of particle i, W is the kernel function, is the displacement partial differential form of the kernel function, W ij represents the value of the kernel function at the relative position of particles i and j, V j is the volume of the particle, μ i and μ j are the viscosity coefficients of particles i and j, r ij is the distance between particles i and , h is the smooth length, g is the gravitational acceleration, and its value is -9.81m / s 2 , γ=7, c0 is the artificial sound speed, ρ 0χ is the reference density of phase χ, F coupling is the coupling force, m i is the mass of particle i, Γ is the set of particles that couple with particle i; Step 6: Calculate the total acceleration of each particle in the discrete calculation domain, update the velocity and position within a single time step, and store the target time data. Repeat the above steps until the calculation time requirement is met. Step 7: Read the exported data, perform visualization, and conduct subsequent image analysis that meets the computational requirements.

2. A meshless simulation method for calculating soil landslide surge according to claim 1, characterized in that: The step 3 specifically includes the following sub-steps: Step 3.1, a series of discrete nodes located in the soil area are set as discrete element method (DEM) particles, and the radius is 0.5 times the distance between discrete nodes. The macroscopic soil deformation process is obtained by calculating the cumulative microscopic displacement of the particles under force; Step 3.2: The formula for calculating the contact force between discrete particles is as follows: 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) Where: F n is the normal contact force, F t is the tangential contact force, δ n is the normal overlap between particles, n is the direction of the line connecting the centers of the two particles, δ t is the tangential overlap between particles, δ t is the relative displacement between contact positions in a single time step, F ndamp With F tdamp Denote the normal and tangential damping forces, respectively, (F t ) t-Δt is the tangential contact force on the particle contact surface at the end of the last time step, μ is the kinetic friction coefficient between particles, and the smaller value of the two kinetic friction coefficients is taken, k n With k t They are the normal stiffness and tangential stiffness of the contact interface, and the Hertz-Mindlin contact model is selected for calculation: Where: G*=0.5(G i +G j ), R*=2R i R j / (R i +R j ), v * =0.5(v i +v j ), i and j represent particle i and particle j respectively; G is the shear modulus, G i and G j denote the shear modulus of particles i and j, respectively, R is the particle radius, R i and R j denote the particle radius of particles i and j respectively, v is the Poisson’s ratio, v i and v j denote the Poisson's ratio of particles i and j, s overlap represents the contact and overlap distance between particles i and j; Step 3.3: Calculate the contact force on a single particle using the following formula: Where: F n total，i is the normal force acting on a single particle, F t total，i is the tangential force acting on a single particle, F n，ij is the normal contact force between particle i and particle , F t，ij is the tangential contact force between particles i and j, and N represents the set of particles in contact with particle i.

3. A meshless simulation method for calculating soil landslide surge according to claim 1, characterized in that: The step 4 specifically includes the following sub-steps: Step 4.1: The water discretization method is the smoothed particle hydrodynamics (SPH) method. The series of discrete nodes in the water area are set as SPH particles, and the radius is the discrete node spacing. The macroscopic water evolution process is obtained by calculating the cumulative microscopic displacement of the particle force. Step 4.2: Calculate the force on fluid particles by referring to the following formula: Where: Dρ i / D t is the density gradient of particle i, Du i / D t is the coupled acceleration of particle i, ρ i and ρ j are the densities of particles i and j, t is time, u j and u i are the velocity vectors of particles j and i, respectively, is the displacement partial differential form of the kernel function, W ij represents the kernel function value under the relative position of particles i and j, m j is the mass of particle j, p i and p j are the fluid pressures of particles i and j, respectively. c0 is the artificial sound velocity. The SPH particle density gradient must be less than 1%. Therefore, the c0 value must be no less than 10 times the maximum velocity of the flow field. r i and r j are the displacement vectors of particles i and j respectively, ρ0 is the reference density (at 20℃ and standard atmospheric pressure, the water density is 1000kg / m 3 ),u ij is the velocity vector difference between particles i and j, δ is the density diffusion term, μ is the viscosity coefficient, γ=7, and g is the gravitational acceleration, which is -9.81 m / s 2 , W is the kernel function, W ij =W(r i -r j ,h), the format is: Where: q = || r i -r j || / h, α dim It is a parameter related to the calculation dimension. In two-dimensional conditions, it is 7 / (4πh 2 ), and 21 / (16πh in three-dimensional conditions 3 ), the smoothing length h is usually 1.5 to 2 times the initial particle spacing in two-dimensional conditions and 1.5 times the particle spacing in three-dimensional conditions, which can ensure the accuracy of the calculation; Step 4.3: Calculate the internal force of a single fluid particle using the following formula: Where: u i is the calculated single particle velocity vector.

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

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

6. A gridless simulation device for calculating soil landslide surge, characterized in that: Includes the following modules, Modeling module, used to model the project area under study and determine the soil landslide and water shape characteristics of the site; The pre-processing module is used to discretize the calculation area, correct irregular soil landslides and water boundary particles, and determine the relevant material characteristic parameters required for calculation; The soil landslide simulation module is used to calculate the stress on the unstable soil area of ​​the landslide, select the appropriate discrete element contact model and discrete element scale, use the discrete element method to calculate the contact force between the particle discrete elements, and obtain the acceleration of each area of ​​the landslide body; The surge simulation module is used to simulate and calculate the whole process of water body and surge using the smooth particle dynamics method. The river water area is discretized into a series of fluid particles to ensure that the size of the fluid particles is close to 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: Where: Du i / D t represents the coupled acceleration of particle i, i represents discrete particle i, j represents discrete particle j, u i represents the speed of particle i, t is the time, p i and p j are the fluid pressures of particles i and j, respectively, and ρ i is the density of particle i, W is the kernel function, is the displacement partial differential form of the kernel function, W ij represents the value of the kernel function at the relative position of particles i and j, V j is the volume of the particle, μ i and μ j are the viscosity coefficients of particles i and j, r ij is the distance between particles i and , h is the smooth length, g is the gravitational acceleration, and its value is -9.81m / s 2 , γ=7, c0 is the artificial sound speed, ρ 0χ is the reference density of phase χ, F coupling is the coupling force, m i is the mass of particle i, Γ is the set of particles that couple with particle i; The time step update module is used to calculate the total acceleration of each particle in the discrete calculation domain, update the velocity and position within a single time step, and store the target time data until the calculation time requirement is met; The post-processing module is used to read the exported data, perform visualization, and conduct subsequent image analysis that meets the computational requirements.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a meshless simulation method for calculating soil landslide surge according to any one of claims 1 to 5 are implemented.

Images