CN113761775B - SPH simulation display method and system for whole disaster evolution process of submarine landslide - Google Patents
SPH simulation display method and system for whole disaster evolution process of submarine landslide Download PDFInfo
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Abstract
The invention discloses an SPH simulation display method and system for the whole disaster evolution process of a submarine landslide, comprising the following steps: dispersing the calculation areas of the submarine slope body and the seawater into particles with set quantity and different physical state attributes, and endowing the particles with corresponding physical and mechanical parameters; a slip-free boundary layer which is used for combining the repulsive particles and the virtual particles is arranged outside the boundary; applying the gravity and periodic wave action of the infinitely covered seawater to the seawater particles, converting Liu Po acting force and construction acting force applied to the slope body into stress boundary conditions of a slope body particle calculation area, applying the boundary particles consisting of repulsive particles and virtual particles, and simultaneously applying displacement boundary conditions; in each calculation time step, determining the catastrophe evolution stage of the submarine slope, selecting a system constitutive equation set corresponding to the catastrophe evolution stage, and performing calculation and solution in a single time step to finish the updating of the particle physical and mechanical information of a solution domain; and displaying the particle physical and mechanical information of the set time step.
Description
Technical Field
The invention relates to the technical field of disaster simulation of a submarine landslide, in particular to an SPH simulation display method and system for the whole process of disaster evolution of the submarine landslide.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
Smooth particle hydrodynamic (Smoothed Particle Hydrodynamics) is a grid-less method that describes the state of a system through a series of particles, which is an adaptive Lagrangian particle method that simulates fluid flow. Compared with the traditional grid-based numerical method, the SPH method has self-adaptability, so that the formula construction of the SPH is not influenced by the randomness of particle distribution, and the problem of great deformation can be handled naturally. The SPH method uses particles as a computational framework for field variable approximation. In the calculation process, the SPH approximation method does not need to provide connection information for particles by using a grid defined in advance, and even when no particle refining operation is performed, the SPH approximation method still works well, so that the difficulty in the traditional FEM and FDM solving process is well avoided. Besides no grid property and self-adaptive property, the SPH method has the characteristic that a Lagrange formula and a particle approximation method can be harmoniously combined. Compared with other gridless methods, the gridless nodes are only used as interpolation points, and particles in the SPH method simultaneously carry material properties and can move under the interaction of external force and internal force. SPH particles have the function of both approximation points and material composition, making SPH particles more flexible. SPH has been demonstrated to yield stable numerical results by solving many problems with significant deformation using arbitrarily distributed points. Although SPH is currently widely used in fields of astrophysics, fluid mechanics, classical mechanics, etc. However, there are few extensive calculations for marine engineering, particularly offshore and subsea slope engineering.
Due to the complexity of the ocean environment, the sea water is wirelessly covered, and when the submarine landslide disaster occurs, unless tsunami is accompanied, people can not find the submarine landslide disaster, and in many cases, the occurrence of the landslide disaster is difficult to detect. The common submarine landslide sliding process has long duration, long sliding distance, large carrying volume and strong destructiveness, and simultaneously can reform submarine topography, thereby causing great threat to the safety of submarine engineering sites and underwater structures. The disaster evolution process of the submarine landslide is mastered, so that the evaluation of the stability of the island slope of the hydraulic filling island is facilitated for the submarine artificial field, and the smoothness of submarine communication optical cables, petroleum engineering facilities and submarine channels is also facilitated.
The obvious difference from land landslide is that in the occurrence process of the submarine landslide, the landslide body interacts with seawater, the proportion of water to the material of the landslide body changes at any time, the physical mechanical property and the physical state of the landslide body also change, and the catastrophe evolution mechanism of the whole process of the submarine landslide is difficult to be effectively revealed only by adopting single calculation of the stability of the landslide body or analysis of a slippage carrying mechanism. In the prior art, no effective measures are described and displayed for the evolution characteristics of the slope body in the catastrophe process of the offshore seabed landslide.
Disclosure of Invention
In view of the above, the invention provides a SPH simulation display method and a system for the whole disaster evolution process of a submarine landslide, which are characterized in that SPH particles with different properties are respectively adopted for seawater and a slope material (a fluid phase and a solid phase) in the submarine landslide process, so that the fluid surface and a reconstructed fluid surface are easy to track, and the visual display of the mixed fluid details and results of the landslide and the seawater can be realized.
In order to achieve the above object, in some embodiments, the following technical solutions are adopted:
a SPH simulation display method for the whole disaster evolution process of a submarine landslide comprises the following steps:
dispersing the calculation areas of the submarine slope body and the seawater into particles with set quantity and different physical state attributes, and endowing the particles with corresponding physical and mechanical parameters; a slip-free boundary layer which is used for combining the repulsive particles and the virtual particles is arranged outside the boundary;
applying the gravity and periodic wave action of the infinitely covered seawater to the seawater particles, converting Liu Po acting force and construction acting force applied to the slope body into stress boundary conditions of a slope body particle calculation area, applying the boundary particles consisting of repulsive particles and virtual particles, and simultaneously applying displacement boundary conditions;
in each calculation time step, determining the catastrophe evolution stage of the submarine slope, selecting a system constitutive equation set corresponding to the catastrophe evolution stage, and performing calculation and solution in a single time step to finish the updating of the particle physical and mechanical information of a solution domain;
and displaying the particle physical and mechanical information of the set time step.
In other embodiments, the following technical solutions are adopted:
an SPH simulation display system of a subsea landslide catastrophically evolving process, comprising:
the ionization module is used for dispersing the calculation areas of the submarine slope body and the seawater into particles with set quantity and different physical state attributes, and endowing the particles with the physical state with corresponding physical and mechanical parameters; a slip-free boundary layer which is used for combining the repulsive particles and the virtual particles is arranged outside the boundary;
the acting force applying module is used for applying the gravity and periodic wave action of the infinitely covered seawater to the seawater particles, converting Liu Po acting force and construction acting force applied to the slope into stress boundary conditions of a slope particle calculation area, applying the stress boundary conditions to boundary particles consisting of repulsive particles and virtual particles, and simultaneously applying displacement boundary conditions;
the particle information updating module is used for determining the catastrophe evolution stage of the submarine slope in each calculation time step, selecting a system constitutive equation set corresponding to the catastrophe evolution stage, and carrying out calculation and solution in a single time step to finish the particle physical mechanics information updating of a solution domain;
and the catastrophe evolution whole process display module is used for displaying the particle physical and mechanical information of the set time step.
In other embodiments, the following technical solutions are adopted:
a terminal device comprising a processor and a computer-readable storage medium, the processor configured to implement instructions; the computer readable storage medium is for storing a plurality of instructions adapted to be loaded by a processor and to perform the SPH simulation demonstration method of the overall process of the disaster evolution of a subsea landslide described above.
In other embodiments, the following technical solutions are adopted:
a computer readable storage medium having stored therein a plurality of instructions adapted to be loaded by a processor of a terminal device and to perform the above-described SPH simulation demonstration method of the overall process of the catastrophic evolution of a subsea landslide.
Compared with the prior art, the invention has the beneficial effects that:
(1) According to one or more embodiments of the invention, the core ideas and computational advantages of smooth particle fluid dynamics are introduced into the field of ocean engineering, so that the sliding accumulation characteristics of changeable seabed landslide bodies and complex sea wave actions and surge forms can be captured, the effective simulation and visual display of the whole disaster evolution process of offshore seabed landslide can be realized, and the method has higher computational efficiency and accuracy.
(2) According to one or more embodiments of the invention, the motion characteristics of landslide body particles and seawater particles can be tracked in real time in the whole solving process, equivalent calculation in a numerical method among particles in different physical states is not needed, complex coupling information interaction operation in the process of adopting different solving methods in different landslide stages is avoided, high-efficiency solving of a problem domain is effectively ensured, and the sliding motion mode, a debris flow carrying mechanism and stacking characteristics of a slope body material of the slope body can be reproduced in real time.
(3) One or more embodiments of the invention are used for modeling the whole solving area, can simultaneously reproduce the sliding accumulation characteristics of the landslide body and the influence of the surge of the sea water in the landslide process, can accurately track the wave height and the action range of the sea wave, and can provide theoretical guidance for the safety protection of offshore ocean engineering.
Additional aspects of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
FIG. 1 is a flowchart of an SPH simulation display method of the whole catastrophe evolution process of a submarine landslide in an embodiment of the invention;
FIG. 2 is a schematic diagram of a particle approximation method in an embodiment of the invention.
Detailed Description
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
Embodiments of the invention and features of the embodiments may be combined with each other without conflict.
The submarine landslide disaster occurrence process has obvious staged characteristics, such as overall sliding, debris flow, turbidity flow and other movement stages. In the above process, with the problem of oversized deformation, the grid-based numerical method will not be applicable. As a representative of the gridless method, SPH method has been successfully applied to simulation of large deformation of solid materials and complex flow processes of mixed fluids. The sea water and the slope material (fluid phase and solid phase) in the submarine landslide process are respectively represented by SPH particles with different properties, the fluid particles and the solid particles are interacted in a discrete form based on the constitutive relation of each fluid particle and the solid particle, and the coupling effect of the fluid particles and the solid particles only needs to ensure that two conditions of no-slip boundary and consistent stress are met. Meanwhile, the SPH method can simulate fluid to obtain data results of each particle in a calculation domain, is easier to track the surface of the fluid and reconstruct the surface of the fluid, is convenient for analyzing the detail of the mixed fluid of the landslide body and the seawater and visualization of the results, and is an effective numerical simulation method for reproducing the movement process of the seabed landslide body.
Example 1
Based on the above description, in one or more embodiments, a SPH simulation display method of the whole process of disaster evolution of a submarine landslide is disclosed, firstly, a calculation area is discretized into a certain number of SPH particles with different physical state attributes without grid, and the particles are subjected to assignment of physical mechanical parameters such as initial density, mass, stress, position, speed, period, amplitude and the like, such as physical mechanical information quality and physical mechanical parameters; setting a slip-free boundary layer combining repulsive particles and virtual particles at the boundary, and compensating the influence of boundary effect on a core calculation area; the sea water gravity and wave action are applied to sea water particles, liu Po acting force and construction acting force applied to the slope body are converted into stress boundary conditions of a slope body particle calculation area, the stress boundary conditions are applied to boundary layer particles, and meanwhile displacement boundary conditions are applied; selecting a proper kernel function and a neighborhood solving radius to form an adjacent particle tight branch domain of all particles in the calculation domain; in each solving time step, carrying out particle traversal search in a tight support area, judging the interaction relation between a slope material and seawater, obtaining the ratio of liquid phase and solid phase particle content of research particles in a particle system, further determining the catastrophe evolution stage of a submarine slope, and simultaneously selecting a system constitutive equation set of a corresponding stage; carrying out continuous equation, momentum equation and energy equation solving on particles in a tight support domain by adopting a display integration method, carrying out density summation, stress solving and energy change rate calculating on the particles in the domain, and further completing the updating of the information of the particles in the solving domain in a single time step; setting a time step interval of calculating result output, and finishing post-processing display of the calculating result by adopting a post-processing program or software.
Referring to fig. 1, the SPH simulation display method of the whole process of the disaster evolution of the submarine landslide specifically includes the following steps:
(1) The method comprises the steps of dispersing a submarine slope calculation area into a certain number of particles with different object state attributes, dividing the submarine slope into units, creating slope model boundary subunits by combining slope surface topography and slope geometric boundaries, carrying out internal interpolation by means of slope contours, uniformly inserting the slope model boundary subunits, constructing a unit group of the whole slope model, selecting a unit center point as coordinates of SPH particles of the slope, and simultaneously endowing SPH particles with physical mechanical parameters such as quality, density, stress, position, speed, movement period and the like;
similarly, sea water SPH particles are created.
(2) The number of layers of boundary layer particles can be increased and staggered, and repulsive particles are added to prevent particles from escaping caused by excessive speed of solid particles; and a certain speed is given to the virtual particles so as to realize the effect of no slip of the speed on the boundary, and a speed no-slip boundary particle layer is created by combining the boundary repulsive particles and the virtual particles.
The method for setting the speed non-slip boundary particle layer is used for weakening the influence of the boundary effect on the calculation region and guaranteeing the accuracy of the calculation region solving result. Since in the motion simulation after the instability of the submarine side slope, the solid particle bottom often causes a large acceleration due to excessive stress, and the velocity is too high to escape from the boundary. By combining the reverse repulsive force of the repulsive particles and the initial speed value of the virtual particles, the boundary sliding of the non-physical penetration boundary of the particles and the virtual particles can be prevented, the accuracy of the SPH approximation method at the boundary region is improved, and the accuracy of the result of calculating the region boundary simulation is effectively ensured. The boundary layer particles are not actually calculated areas, and are only used for compensating and correcting the solving of the real particles on the boundary of the calculated areas.
(3) The gravity action and wave load of the sea water are applied to the sea water particles, liu Po acting force and construction acting force applied to the slope are converted into stress boundary conditions of the slope particle calculation area, and meanwhile constraint is converted into displacement boundary conditions.
The submarine side slope is in an infinite seawater coverage environment, the seawater depth also changes along with the extension of the side slope, the calculation cost and the calculation efficiency are limited, and the whole sea area cannot be subjected to discretization modeling, so that only a potential landslide area and a slope body are covered with a seawater layer with a certain height to carry out mesh-free discretization particle modeling. In addition to seafloor earthquakes, seafloor volcanic activities, wave action generally induces the main factor of seafloor landslides. The SPH method has an inherent advantage in capturing and tracking interfaces of substances of different phases (different object states), so that loading of wave actions of different waveforms can be performed.
(4) And selecting a proper smooth kernel function and a particle neighborhood searching radius, carrying out particle pairing by adopting a linked list searching method, forming a supporting domain and an influence domain of all SPH particles, and determining the interaction relation among the particles.
Integrating the arbitrary function and the smooth kernel function using an integral representation function, replacing the kernel function δ (x-x ') of the δ function with the smooth function W (x-x', h), the integral representation of f (x) can be expressed as:
f(x)≈∫ Ω f(x′)W(x-x′，h)dx′；
w (x-x', h) is referred to as a smooth kernel, also known as a kernel, in the SPH method. W (x-x', h) is defined in the tight branch region, and in the smooth function, h is the smooth length of the affected area defining the smooth function W. Typically, the supporting domain of the particle is the same as the influencing domain.
The particle approximation of the function at particle i can ultimately be expressed as:
wherein W is ij ＝W(x i -x j H), any function value at particle i may be approximated by a weighted average of the function values of all particles relative in its immediate neighborhood by applying a smoothing function.
(5) And in each calculation time step, performing traversal search in a particle tight support area to obtain the relative speed among the slope particles and the content ratio of the seawater particles to the slope particles in the tight support area, judging the interaction relation between the slope material and the seawater, and further determining the catastrophe evolution stage of the submarine slope.
(5-1) the process of landslide on the sea floor is often accompanied by significant stepwise features such as stages of global slippage, debris flow, mud flow, turbidity current, etc. Through the indoor test of the particle concentration, the volume concentration and the viscosity of the submarine landslide body material, the seawater particle content ratio (liquid phase alpha) in the particle system in different catastrophe evolution stages is calibrated 1 ) Slope particle content ratio (solid phase alpha) 2 ) And a ratio beta of the two-phase particle contents i ；α 1 、α 2 The concentration of the particles is corresponding to the concentration of the particles after certain conversion; beta i After a certain conversion, the volume concentration is corresponding to the volume concentration; wherein the ratio beta of the two-phase particle contents i The concrete calculation is as follows：
In the embodiment, beta is obtained in the integral critical slip unstable state of the slope body i ＝β 1 Landslide mass debris flow stage beta i ＝β 2 Landslide mass mud flow stage beta i ＝β 3 Landslide mass turbidity current stage beta i ＝β 4 。
(6) And selecting constitutive equations of the particle system of the corresponding stage according to the catastrophe stage judgment in the particle tight support domain. The whole movement and sliding stage of the landslide body is that the relative movement speed among solid phase particles of the landslide body is close to zero; for offshore seabed sediment, the on-site test and the indoor test can determine that the slope material can be changed from solid to liquid only when the water content of the slope reaches a certain value, and relative displacement occurs between the slope materials, and at the moment, the migration of the landslide is in a debris flow mode. As the landslide body continues to slide, the sea water interacts with the landslide body, and when the solid particle volume of the landslide body exceeds a certain value, the landslide body slides to present the mud flow characteristic of the non-Newtonian fluid. As the slope continues to slide, the water content of the slope material further increases, and sliding of the slope will exhibit a turbidity current flow pattern.
(6-1) describing constitutive relation and yield state of the slope body by adopting a Drucker-Prager yield criterion aiming at the integral slip phase of the slope body, wherein the yield condition can be expressed as:wherein I is 1 And j 2 Alpha, which is the first and second invariants of the stress tensor φ And k c Is constant and can be obtained by the cohesive force c of the slope material and the internal friction angle phi.
For plane strain problems, the constant α φ And k c Is that
(6-2) aiming at the debris flow stage of the landslide body, the mixed high-density fluid of the landslide body material and the seawater has obvious non-Newtonian fluid characteristics, the Bingham model (Bingham model) is adopted to represent the rheological characteristics of the debris flow,ultimate shear stress τ 0 Also known as yield stress. The rheological parameter η is called the plastic viscosity and is used to characterize the viscosity of a material when flowing.
(6-3) aiming at the mud flow flowing stage of the landslide body, the particle content concentration of the solid-phase slope body is larger than that of the conventional ocean current and the turbidity current, the mud flow can be regarded as a non-Newtonian fluid with viscoplasticity characteristics, and a Herschel-bulk generalized Bingham plastomer model is adopted:
where k is the consistency coefficient, related to the fluid properties, in Pa.s n The method comprises the steps of carrying out a first treatment on the surface of the n is a fluidity index, dimensionless; τ 0 For the extreme dynamic shear stress, the stress is,for shear deformation speed>
The model integrates the characteristics of the Bingham model and the power law model.
(6-4) aiming at a turbidity current stage of sliding of the landslide body, the landslide body is gradually converted into a sand-carrying water body, the characteristics of Newton fluid are provided, the landslide body treatment at the stage is consistent with the essence of a traditional SPH hydrodynamic model by adopting an SPH water-sand coupling model, and a momentum equation in a tensor form is as follows:
where u is the particle velocity, ρ is the particle density, g is the gravitational acceleration, and σ is the full stress tensor.
(7) In each time step, carrying out particle density summation in a tight branch area by adopting a display integration method, searching adjacent particles of particles, solving particle density information at the moment, and further carrying out stress solving and momentum change rate calculating by a system state equation; and then updating the physical and mechanical information of the particles in the solving domain, and entering the next calculation time step cycle after updating the system information of the particles.
In each time step, combining with fig. 2, solving the SPH approximation formula of the continuity equation of the particle system through a kernel approximation and a particle approximation method to obtain the change rate of the particle density in the particle tight support; carrying out stress change solving of the particle system according to the SPH approximation of the momentum equation; and then the momentum change rate of the particle system is obtained by the SPH approximation formula of the energy equation. After the equation of the particle system is solved, the particle information is updated, and the method mainly comprises the steps of coordinates, stress, acceleration, momentum change rate and the like of particles, and then the next time step is calculated.
(8) The output time step interval of the solving result of the particle system is set, the physical and mechanical information of the particle system is output after the solving time step is set at each interval, the output result is processed in batches through a post-processing program or software, and the whole process display of the disaster evolution of the submarine landslide can be performed in real time.
It should be noted that the process of performing the visual display is possible for those skilled in the art according to the prior art, and will not be described in detail herein.
Example two
In one or more embodiments, a SPH simulation display system for a subsea landslide catastrophe evolution whole process is disclosed, comprising:
the ionization module is used for dispersing the calculation areas of the submarine slope body and the seawater into particles with set quantity and different physical state attributes, and endowing the particles with the physical state with corresponding physical and mechanical parameters; a slip-free boundary layer which is used for combining the repulsive particles and the virtual particles is arranged outside the boundary;
the acting force applying module is used for applying the gravity and periodic wave action of the infinitely covered seawater to the seawater particles, converting Liu Po acting force and construction acting force applied to the slope into stress boundary conditions of a slope particle calculation area, applying the stress boundary conditions to boundary particles consisting of repulsive particles and virtual particles, and simultaneously applying displacement boundary conditions;
the particle information updating module is used for determining the catastrophe evolution stage of the submarine slope in each calculation time step, selecting a system constitutive equation set corresponding to the catastrophe evolution stage, and carrying out calculation and solution in a single time step to finish the particle physical mechanics information updating of a solution domain;
and the catastrophe evolution whole process display module is used for displaying the particle physical and mechanical information of the set time step.
It should be noted that, the specific implementation manner of each module has been described in detail in the first embodiment, and will not be described herein again.
Example III
In one or more embodiments, a terminal device is disclosed, including a server including a memory, a processor, and a computer program stored on the memory and executable on the processor, the processor implementing the SPH simulation display method of the overall process of the catastrophic evolution of a subsea landslide in embodiment one when executing the program. For brevity, the description is omitted here.
It should be understood that in this embodiment, the processor may be a central processing unit CPU, and the processor may also be other general purpose processors, digital signal processors DSP, application specific integrated circuits ASIC, off-the-shelf programmable gate array FPGA or other programmable logic device, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory may include read only memory and random access memory and provide instructions and data to the processor, and a portion of the memory may also include non-volatile random access memory. For example, the memory may also store information of the device type.
In implementation, the steps of the above method may be performed by integrated logic circuits of hardware in a processor or by instructions in the form of software.
Example IV
In one or more embodiments, a computer-readable storage medium is disclosed, in which are stored a plurality of instructions adapted to be loaded by a processor of a terminal device and to perform the SPH simulation demonstration method of the overall process of the disaster evolution of a subsea landslide in example one.
While the foregoing description of the embodiments of the present invention has been presented in conjunction with the drawings, it should be understood that it is not intended to limit the scope of the invention, but rather, it is intended to cover all modifications or variations within the scope of the invention as defined by the claims of the present invention.
Claims (8)
1. The SPH simulation display method for the whole disaster evolution process of the submarine landslide is characterized by comprising the following steps of:
dispersing the calculation areas of the submarine slope body and the seawater into particles with set quantity and different physical state attributes, and endowing the particles with corresponding physical and mechanical parameters; a slip-free boundary layer which is used for combining the repulsive particles and the virtual particles is arranged outside the boundary;
applying the gravity and periodic wave action of the infinitely covered seawater to the seawater particles, converting Liu Po acting force and construction acting force applied to the slope body into stress boundary conditions of a slope body particle calculation area, applying the boundary particles consisting of repulsive particles and virtual particles, and simultaneously applying displacement boundary conditions;
in each calculation time step, determining the catastrophe evolution stage of the submarine slope, selecting a system constitutive equation set corresponding to the catastrophe evolution stage, and performing calculation and solution in a single time step to finish the updating of the particle physical and mechanical information of a solution domain;
displaying the physical and mechanical information of the particles in the set time step;
the catastrophe evolution stage of the submarine slope body specifically comprises the following steps: [1]
the whole movement and sliding stage of the landslide body is that the relative movement speed among solid phase particles of the landslide body is close to zero;
when the water content of the slope reaches a set value, the slope material is changed from solid to liquid, relative displacement occurs between the slope materials, and at the moment, the movement of the landslide is in a debris flow mode;
along with the continuous sliding of the landslide body, the seawater interacts with the landslide body, and when the solid particle volume of the landslide body exceeds a set value, the sliding of the landslide body presents the mud flow characteristic of the non-Newtonian fluid;
as the slope body continues to slide, the water content of the slope body material is further increased, and the sliding slope body slides to present a turbidity current flowing mode;
for the integral sliding stage of the slope body, adopting a Drucker-Prager yield criterion to describe the constitutive relation and the yield state of the slope body, wherein the yield condition can be expressed as follows:wherein->And->First and second invariants as stress tensor,/>And->Is constant, cohesive force through the slope material +.>Angle of internal friction->Obtaining;
for plane strain problems, constantsAnd->Is->, />；
Aiming at the debris flow stage of the landslide body, the mixed high-density fluid of the slope body material and the seawater has obvious non-Newtonian fluid characteristic, adopts the Bingham model to represent the rheological characteristic of the debris flow,， />limit shear stress->Also called yield stress, rheological parameter->Referred to as plastic viscosity, is used to characterize the amount of viscosity of a material when flowing;
aiming at the mud flow flowing stage of the landslide body, the content concentration of solid-phase slope body particles is larger than that of conventional ocean current and turbidity current, the mud flow can be regarded as non-Newtonian fluid with viscoplasticity characteristics, and a Herschel-bulk generalized Bingham plastomer model is adopted:
；
wherein,is the consistency coefficient, related to the fluid properties, in +.>；/>Is a fluidity index, dimensionless; />For limiting dynamic shear stress->For shear deformation speed>；
Aiming at a turbidity current stage of sliding of a landslide body, the landslide body is gradually converted into a sand-carrying water body, the characteristics of Newton fluid are provided, the landslide body treatment at the stage is consistent with the essence of a traditional SPH hydrodynamic model by adopting an SPH water-sand coupling model, and a tensor form momentum equation is as follows:
；
wherein,for particle speed, +.>For particle density->Acceleration of gravity, ++>Is the full stress tensor;
through the indoor test of the particle concentration, the volume concentration and the viscosity of the landslide body material, the content ratio of seawater particles to slope body particles in the particle system in different catastrophe evolution stages is calibrated;
and obtaining a corresponding catastrophe evolution stage based on the obtained particle content ratio in the calculation time step.
2. The SPH simulation display method of the whole process of the catastrophe evolution of the submarine landslide according to claim 1, wherein the calculation area of the submarine slope is discretized into a set number of particles with different physical state attributes, and the particles with different physical states are endowed with corresponding physical and mechanical parameters, and the method specifically comprises the following steps:
the method comprises the steps of dividing a sea bottom slope body into units, creating a slope model boundary subunit by combining the surface topography of the slope and the geometric boundary of the slope, carrying out internal interpolation by means of the slope contour, uniformly inserting the model subunit, constructing a unit group of the whole slope model, selecting a unit center point as coordinates of SPH particles of the slope, and simultaneously endowing the SPH particles with physical and mechanical parameters of quality, density, stress, position, speed and movement period.
3. The SPH simulation demonstration method of the overall catastrophe evolution process of a submarine landslide of claim 1, further comprising, prior to determining the catastrophe evolution stage of the submarine landslide: and selecting a particle approximate kernel function and a smooth kernel radius, and performing particle pairing to form a tight branch domain and an influence domain of all SPH particles.
4. A SPH simulation display method of the overall catastrophe evolution process of a submarine landslide as recited in claim 3, wherein determining the catastrophe evolution stage of the submarine landslide in each calculation time step comprises:
and in each calculation time step, performing traversal search in a particle tight support area to obtain the relative speed among the slope particles and the content ratio of the seawater particles to the slope particles in the tight support area, and determining the catastrophe evolution stage of the submarine slope.
5. The SPH simulation display method of the whole process of the disaster evolution of the submarine landslide as claimed in claim 1, wherein the calculation solution is carried out in a single time step to complete the updating of the physical and mechanical information of particles in a solution domain, and the method specifically comprises the following steps:
in each time step, solving an SPH approximation formula of a continuity equation of the particle system through a kernel approximation and a particle approximation method to obtain a particle density change rate in a tight support; further, carrying out stress solving and momentum change rate calculating by a system state equation; and updating the information of the particle coordinates, stress, acceleration and momentum change rate of the solving domain.
6. An SPH simulation display system of the whole disaster evolution process of a submarine landslide, which is based on the SPH simulation display method of the whole disaster evolution process of the submarine landslide as claimed in claims 1-5, and is characterized by comprising:
the ionization module is used for dispersing the calculation areas of the submarine slope body and the seawater into particles with set quantity and different physical state attributes, and endowing the particles with the physical state with corresponding physical and mechanical parameters; a slip-free boundary layer which is used for combining the repulsive particles and the virtual particles is arranged outside the boundary;
the acting force applying module is used for applying the gravity and periodic wave action of the infinitely covered seawater to the seawater particles, converting Liu Po acting force and construction acting force applied to the slope into stress boundary conditions of a slope particle calculation area, applying the stress boundary conditions to boundary particles consisting of repulsive particles and virtual particles, and simultaneously applying displacement boundary conditions;
the particle information updating module is used for determining the catastrophe evolution stage of the submarine slope in each calculation time step, selecting a system constitutive equation set corresponding to the catastrophe evolution stage, and carrying out calculation and solution in a single time step to finish the particle physical mechanics information updating of a solution domain;
and the catastrophe evolution whole process display module is used for displaying the particle physical and mechanical information of the set time step.
7. A terminal device comprising a processor and a computer-readable storage medium, the processor configured to implement instructions; a computer readable storage medium for storing a plurality of instructions adapted to be loaded by a processor and to perform the SPH simulation demonstration method of the overall process of the catastrophic evolution of a subsea landslide of any of claims 1-5.
8. A computer readable storage medium having stored therein a plurality of instructions adapted to be loaded by a processor of a terminal device and to perform the SPH simulation demonstration method of the overall process of the catastrophic evolution of a subsea landslide of any of claims 1-5.
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