A method and system for simulating slow landslide movement based on viscoplastic SPH model

Abstract

The invention provides a method and system for simulating the movement process of a slow landslide based on a viscoplastic SPH model. According to landslide source information, SPH particles containing solid and liquid phases are generated, and rheological parameter information of SPH particles in different regions is given according to geological survey data; then the following iterative calculations are performed: the non-viscous deformation shear force of each SPH particle at the current time step n is calculated; the viscous deformation shear force of each SPH particle at the current time step n is calculated; the time step iteration step length is updated according to the displayed calculation stability condition; the particle velocity of the n+1 time step is updated, and the position of the deformed particle is obtained; and the calculation is terminated when the calculation meets the convergence condition.

Description

Technical Field

[0001] The invention belongs to the technical field of geological disaster simulation, and in particular relates to a method and system for simulating the movement process of a slow landslide based on a viscoplastic SPH model. Background Art

[0002] At present, a series of meshless numerical calculation methods represented by smooth particle fluid dynamics and material point method have been widely used in the analysis of large deformation dynamic processes such as geological disasters. However, due to the CFL conditions of numerical solutions, the calculation time step of existing schemes is mostly limited to 0.1 seconds or even less. For slow landslides whose deformation and sliding process can last for months or even years, such a calculation time step will result in too much calculation and is not feasible in the analysis of actual engineering. Summary of the invention

[0003] In view of the defects and shortcomings of the prior art, the present invention proposes a simulation scheme for the slow landslide movement process based on the viscoplastic SPH model by introducing that the landslide is shallow, the dominant factor of the landslide deformation movement is characterized by the viscoplastic model, and the acceleration is approximately 0. This scheme can effectively relax the time step under the CFL condition restriction. Compared with the traditional scheme, under certain conditions, the time step of about 0.1s can be extended to about 0.4 hours. In this way, it is possible to effectively simulate slow landslides whose deformation lasts for months or even years, laying an important foundation for understanding the catastrophic mechanism of such disasters and formulating scientific and effective disaster reduction measures.

[0004] The technical problem to be solved by the present invention is that the numerical simulation method for display solution is unable to be applied in practice due to the limited (very small) calculation step size for long-duration disaster processes such as slow landslides, resulting in an overall large amount of calculation. A method and system for simulating the movement process of slow landslides based on the viscoplastic SPH model is proposed.

[0005] The present invention constructs a slow landslide movement process algorithm based on the viscoplastic SPH model, especially introduces the assumption that the acceleration is approximately 0 in the momentum equation, and constructs the parabolic control equation of the landslide movement velocity through the viscoplastic rheological model, which solves the problem that the traditional display solution method cannot effectively simulate the slow landslide with long-term deformation due to the limitation of time step, and is of great value for understanding the action mechanism of such landslides and taking effective control measures.

[0006] The technical solution specifically adopted by the present invention to solve the technical problem is:

[0007] A method for simulating slow landslide movement based on viscoplastic SPH model:

[0008] According to the landslide source information, SPH particles containing solid and liquid phases are generated, and rheological parameter information of SPH particles in different regions is given according to geological survey data;

[0009] Then perform the following iterative calculations:

[0010] Calculate the inviscid deformation shear force of each SPH particle at the current time step n;

[0011] Calculate the viscous deformation shear force of each SPH particle at the current time step n;

[0012] According to the displayed calculation stability conditions, the time step iteration step is updated;

[0013] Update the particle velocity at the n+1 time step and obtain the deformed particle position;

[0014] The calculation ends when the convergence condition is met.

[0015] Furthermore, the basic properties of the SPH particles include: flow coefficient f_gama, soil layer depth h, atmospheric pressure p_atm, rheological model parameter f_n and shear strength s_b; the rheological parameter information is obtained by radial basis function interpolation based on the positional relationship between the particle's spatial coordinate matrix x_coor(:,2) and the geological survey sampling points.

[0016] Furthermore, the non-viscous deformation shear force S_nv(:,2) of each SPH particle at the current time step n is calculated based on the general viscoplastic rheological model:

[0017] First, calculate the direction vector nv(:,2) of all current particle motions: traverse the velocity matrix v(:,2) of all particles, and traverse all particles according to the following formula to obtain the direction vector nv(:,2) of particle motion:

[0018]

[0019] Among them, the mod() function is used to calculate the modulus of the velocity vector;

[0020] Then, according to the soil shear strength s_b, the non-viscous deformation shear force S_nv(:,2) is calculated:

[0021]

[0022] in, ρ (:) is the density list of each particle, h (:) is the soil depth list of each particle, b (:) is the gravitational acceleration list, which is usually a fixed value. .

[0023] Furthermore, based on the general viscoplastic rheological model, the viscous deformation shear force S_v(:,2) of each SPH particle at the current time step n is calculated using one of the following forms:

[0024] Form 1:

[0025]

[0026] Form 2:

[0027]

[0028] Among them, the coefficient m is the inverse of the rheological model parameter f_n, and the coefficient B(:) is calculated according to the flow coefficient f_gama and the soil layer depth according to the following formula:

[0029] .

[0030] Furthermore, the stability condition is calculated according to the display, and the time step iteration step is updated. Specifically include:

[0031] Calculate the model diffusion coefficient D(:) for each SPH particle:

[0032]

[0033] Traverse all particles and calculate the distance between each particle pair , for particles i and j:

[0034]

[0035] Go through all particles and get the maximum iteration time step :

[0036] .

[0037] Furthermore, the updating of the particle velocity at the n+1 time step and obtaining the position of the particle after deformation is specifically as follows:

[0038] Update the particle speed at time step n+1 , specifically one of the following forms:

[0039] or

[0040]

[0041] in, P (:) is the pressure term of the momentum equation, grad () is the gradient operator;

[0042] According to the average velocity of the previous and next time steps, the particle coordinates of the n+1 time step are obtained. :

[0043] .

[0044] Furthermore, the convergence condition is determined by the maximum time and the minimum displacement change. When the calculation time step exceeds the maximum calculation time, or the displacement change of the previous and next time steps is less than the limit value, the convergence condition is triggered.

[0045] And, a slow landslide motion process simulation system based on viscoplastic SPH model, including:

[0046] The generation module is used to generate SPH particles containing solid and liquid phases according to the landslide source information, and to give rheological parameter information of SPH particles in different regions according to geological survey data;

[0047] And iterative calculation module, used to perform the following iterative calculations:

[0048] Calculate the inviscid deformation shear force of each SPH particle at the current time step n;

[0049] Calculate the viscous deformation shear force of each SPH particle at the current time step n;

[0050] According to the displayed calculation stability conditions, the time step iteration step is updated;

[0051] Update the particle velocity at the n+1 time step and obtain the deformed particle position;

[0052] The calculation ends when the convergence condition is met.

[0053] An electronic device comprises a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of the method for simulating the motion process of a slow landslide based on a viscoplastic SPH model are implemented as described above.

[0054] A non-transitory computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for simulating a slow landslide motion process based on a viscoplastic SPH model as described above.

[0055] Considering the current numerical simulation methods such as smooth particle fluid dynamics and material point method, in the process of solving long-lasting disaster processes such as slow landslides, the calculation step size is limited (very small), resulting in the problem that the overall calculation amount is too large to be practically applied. The present invention and its preferred solution solve the problem of too small time step size in traditional methods due to CFL conditions by assuming that the landslide is shallow, the dominant factor of the landslide deformation movement can be described by a viscoplastic model, and the acceleration is approximately 0. It can achieve effective simulation of slow landslides whose deformation lasts for months or even years, laying an important foundation for understanding the catastrophic mechanism of such disasters and formulating scientific and effective disaster reduction measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0057] Figure 1 The figure is a flow chart of a method according to an embodiment of the present invention.

[0058] Figure 2 This is a schematic diagram of the initial state of a landslide according to an embodiment of the present invention.

[0059] Figure 3 This is a schematic diagram of the state of a landslide after sliding for 60 days according to an embodiment of the present invention. DETAILED DESCRIPTION

[0060] In order to make the features and advantages of this patent more obvious and easy to understand, the following embodiments are specifically described in detail as follows:

[0061] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0062] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0063] The present invention aims at the problem that the current numerical simulation methods such as smooth particle fluid dynamics and material point method cannot be used in practice because the calculation step size is limited (very small) in the process of solving disaster processes such as slow landslides that last a long time, resulting in too large an overall calculation amount. A method for simulating the movement process of slow landslides based on the viscoplastic SPH model is proposed, and on this basis, a corresponding simulation system is constructed based on a computer system. By assuming that the landslide is shallow, the dominant factor of the landslide deformation movement can be described by the viscoplastic model, and the acceleration is approximately 0, the problem of the traditional method having too small a time step size under the CFL condition is solved. It can achieve effective simulation of slow landslides whose deformation lasts for months or even years, laying an important foundation for understanding the catastrophic mechanism of such disasters and formulating scientific and effective disaster reduction measures. The specific implementation flow chart is shown below. Figure 1 As shown. It mainly includes the following 6 steps:

[0064] Step 1: Generate SPH particles containing solid and liquid phases according to the landslide source information, and assign rheological parameter information of SPH particles in different regions according to geological survey data;

[0065] Step 2: Calculate the inviscid deformation shear force of each SPH particle at the current time step n;

[0066] Step 3: Calculate the viscous deformation shear force of each SPH particle at the current time step n;

[0067] Step 4: Update the time step iteration step size according to the displayed calculated stability conditions;

[0068] Step 5: Update the particle velocity at the n+1 time step and obtain the position of the deformed particle;

[0069] Step 6: Determine the calculation convergence condition. If it is satisfied, end the calculation. If not, return to step 2.

[0070] Select a specific slow landslide case (initial landslide volume see Figure 2 ), according to the method flow ( Figure 1 ) for a detailed introduction:

[0071] Step 1: Generate SPH particles containing solid and liquid phases according to the landslide source information, and assign rheological parameter information to SPH particles in different regions according to the geological survey data. Take the generation of 2000 landslide source particles as an example, and assign all particles information including flow coefficient f_gama, soil layer depth h, atmospheric pressure p_atm, rheological model parameter f_n, and shear strength s_b. The above data is used as the basic attributes of each SPH particle, and is obtained through radial basis function interpolation based on the spatial coordinate matrix x_coor (2000, 2) of the particle and the positional relationship between the geological survey sampling points.

[0072] Step 2: Calculate the inviscid deformation shear force S_nv(2,2000) of each SPH particle at the current time step n; including the following steps:

[0073] ① Calculate the direction vector nv(2000,2) of all current particle movements. Traverse the velocity matrix v(2000,2) of all particles, and traverse all particles according to the following formula to obtain the direction vector nv(2000,2) of particle movement:

[0074] (1)

[0075] Among them, the mod() function is used to calculate the modulus of the velocity vector.

[0076] ② According to the soil shear strength s_b, calculate the non-viscous deformation shear force S_nv (2000,2)

[0077] (2)

[0078] Among them, the soil shear strength s_b is taken as 28500Pa, the density ρ 1963kg / m 3 , the gravitational acceleration is taken as .

[0079] Step 3: Calculate the viscous deformation shear force S_v(2000,2) of each SPH particle at the current time step n. The calculation method is based on the general viscoplastic rheological model. According to different viscoplastic flow laws, the following two forms can be selected:

[0080] Form ①:

[0081] (3)

[0082] Form ②:

[0083] (4)

[0084] Among them, the coefficient m is the reciprocal of the rheological model parameter f_n, which is taken as 1 here. The coefficient B(:) is calculated according to the flow coefficient f_gama and the soil layer depth according to the following formula:

[0085] (5)

[0086] Here, according to the average soil depth, the calculation result is B=0.019m / h=5.28*10 -6 m / s.

[0087] Step 4: Calculate the stability condition based on the display and update the time step iteration step . It includes the following two steps:

[0088] ① Calculate the model diffusion coefficient D(:) of each SPH particle:

[0089] (6)

[0090] ② Go through all particles and calculate the distance between each particle pair , taking particles i and j as an example:

[0091] (7)

[0092] ③ Go through all particles and get the maximum iteration time step :

[0093] (8)

[0094] Step 5: Update the particle velocity at the n+1 time step and obtain the deformed particle position, which includes the following two steps:

[0095] ① Update the particle speed at the n+1 time step :

[0096] Corresponding to form 1 in step 3:

[0097]

[0098] Corresponding to form 2 in step 3:

[0099] (9)

[0100] in, P (:) is the pressure term of the momentum equation, grad () is the gradient operator.

[0101] ② According to the average velocity of the previous and next time steps, the particle coordinates of the n+1 time step are obtained :

[0102] (10).

[0103] Step 6: Determine the calculation convergence conditions. If they are met, end the calculation. If not, return to step 2. The convergence conditions are determined by the maximum time and the minimum displacement change. When the calculation time step exceeds the maximum calculation time, which is set to 100 days, that is, 8.64*10 6 seconds, or the displacement change of the previous and next time steps is less than the limit value, this embodiment is set to 0.005m, that is, 0.005m in 4 hours, which is 3.472*10 -7 m / s. If any of the above conditions is met, the convergence condition is triggered. The landslide state after calculation is completed can be found in Figure 3 .

[0104] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0105] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0106] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0107] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0108] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0109] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

[0110] This patent is not limited to the above-mentioned optimal implementation mode. Anyone can derive various other forms of a method and system for simulating the slow landslide movement process based on the viscoplastic SPH model under the inspiration of this patent. All equal changes and modifications made according to the scope of the patent application of the present invention should be covered by this patent.

Claims

1. A method for simulating the movement of slow landslides based on the viscoplastic SPH model, characterized by: According to the landslide source information, SPH particles containing solid and liquid phases are generated, and rheological parameter information of SPH particles in different regions is given according to geological survey data; Then perform the following iterative calculations: Calculate the inviscid deformation shear force of each SPH particle at the current time step n; Calculate the viscous deformation shear force of each SPH particle at the current time step n; Calculate the stability condition according to the display and update the time step iteration step ; Update the particle velocity at the n+1 time step and obtain the deformed particle position; When the calculation meets the convergence condition, the calculation ends; The basic properties of the SPH particles include: flow coefficient f_gama, soil layer depth h, atmospheric pressure p_atm, general viscoplastic rheological model parameters f_n and shear strength s_b; the rheological parameter information is obtained by radial basis function interpolation based on the spatial coordinate matrix x_coor (:, 2) of the particle and the positional relationship between the geological survey sampling points; Based on the general viscoplastic rheological model, the non-viscous deformation shear force S_nv(:,2) of each SPH particle at the current time step n is calculated: First, calculate the direction vector nv(:,2) of all current particle movements: traverse the velocity matrix v(:,2) of all particles, and traverse all particles according to the following formula to obtain the direction vector nv(:,2) of particle movement: ； Among them, the mod() function is used to calculate the modulus of the velocity vector; Then, according to the soil shear strength s_b, the non-viscous deformation shear force S_nv(:,2) is calculated: ； in, ρ (:) is the density list of each particle, h (:) is the soil depth list of each particle, b (:) is the gravitational acceleration list; The general viscoplastic rheological model uses one of the following forms to calculate the viscous deformation shear force S_v(:,2) of each SPH particle at the current time step n: Form 1: ； Form 2: ； Among them, the coefficient m is the reciprocal of the general viscoplastic rheological model parameter f_n, and the coefficient B(:) is the flow coefficient f_gama and the soil layer depth h(:) calculated according to the following formula: ； The stability condition is calculated according to the display, and the time step iteration step is updated Specifically include: Calculate the model diffusion coefficient D(:) for each SPH particle: ； Traverse all particles and calculate the distance between each particle pair , for particles i and j: ； Traverse all particles and get the time step iteration step : ； The updating of the particle velocity at the n+1 time step and obtaining the position of the particle after deformation is specifically as follows: Update the particle speed at the n+1 time step , specifically one of the following forms: or ； in, P (:) is the pressure term of the momentum equation, grad () is the gradient operator; According to the average velocity of the previous and next time steps, the particle coordinates of the n+1 time step are obtained: : 。 2. The method for simulating the slow landslide movement process based on the viscoplastic SPH model according to claim 1 is characterized in that: The convergence condition is determined by the maximum time and the minimum displacement change. When the calculation time step exceeds the maximum calculation time, or the displacement change of the previous and next time steps is less than the limit value, the convergence condition is triggered.

3. A slow landslide motion simulation system based on viscoplastic SPH model, characterized in that: The method for simulating the slow landslide movement process based on the viscoplastic SPH model as claimed in claim 1 comprises: The generation module is used to generate SPH particles containing solid and liquid phases according to the landslide source information, and to give rheological parameter information of SPH particles in different regions according to geological survey data; And iterative calculation module, used to perform the following iterative calculations: Calculate the inviscid deformation shear force of each SPH particle at the current time step n; Calculate the viscous deformation shear force of each SPH particle at the current time step n; Calculate the stability condition according to the display and update the time step iteration step ; Update the particle velocity at the n+1 time step and obtain the deformed particle position; The calculation ends when the convergence condition is met.

4. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the method for simulating the slow landslide movement process based on the viscoplastic SPH model as described in claim 1 or 2 are implemented.

5. A non-transitory 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 method for simulating the movement process of a slow landslide based on a viscoplastic SPH model as described in claim 1 or 2 are implemented.

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