Method and system for simulating buckling catastrophe large deformation of barrier dam under extreme working condition

Abstract

The invention provides a dam instability catastrophe large deformation simulation method and system under extreme working conditions. The method comprises the steps that 1, a solid model is constructed and dispersed into an equidistant particle model; respectively endowing each particle with a basic parameter value and setting a particle type; 2, constructing a general constitutive model for representing the fluidization phase change behavior of the soil body; 3, particle contact judgment is carried out with barrage dam soil particles, barrage dam block stone particles, vehicle particles and rolling stone particles as center particles, and the deformation behaviors of the center particles are simulated based on the constructed general constitutive model representing the fluidization phase change behaviors of the soil body; and step 4, carrying out visual output on the calculated characteristic information of each central particle. According to the method, the refined numerical simulation method for the instability catastrophe large deformation of the barrier dam considering the combined action of the landslide disaster chain impact, the vehicle load and the rolling stone impact is established, and the stability of the barrier dam and the whole subsequent large deformation damage process under the extreme working condition can be predicted.

Description

Technical Field

[0001] The invention relates to the technical field of landslide simulation, and in particular to a method and system for simulating large deformation of a landslide dam due to instability disaster under extreme working conditions. Background Art

[0002] The collapse, landslide, debris flow and other deposits produced by the dynamic geological action of the river valley slope, the moraine produced by the glacier snowmelt activity, the volcanic eruption and other materials form natural dams, which block the valley riverbed horizontally, resulting in the original water system being forcibly blocked. The natural dam body formed by the waterlogging of the upstream section is called a barrier dam. At present, the slope stability and large deformation calculation of the barrier dam are important contents for evaluating the safety of the barrier dam project. The barrier dam is formed by the landslide blocking the river. It can be seen that there is still the possibility of secondary triggering of landslides at the dam site. In the face of potential natural disasters such as secondary landslides, rockfall impacts, emergency vehicle loads or other extreme situations, the barrier dam may become unstable. Once the barrier dam is unstable and collapsed, the upstream barrier lake will quickly collapse in a short time, thereby inducing a flood, which seriously threatens the safety of life and property of the people in the downstream surrounding areas and the safe operation of the hydropower projects in the basin.

[0003] In recent years, some progress has been made in the calculation of slope stability and large deformation of dams, but there are still some challenges and difficulties. First, in terms of the research progress of slope stability of dams, a relatively complete slope stability analysis method has been established, but most of these methods only perform static analysis on the small deformation stage. Traditional slope stability analysis mainly relies on empirical formulas and simplified methods, such as the limit equilibrium method, but these methods have limitations when considering complex geological conditions and nonlinear effects, and it is difficult to truly characterize the soil-rock mixture structure inside the dam. Large deformation calculation refers to the quantitative description and prediction of the deformation process of the dam when it slips, scours, and fails. With the continuous development of computer technology and numerical simulation methods, numerical methods such as mesh-based methods such as finite element analysis, meshless methods such as smoothed particle fluid dynamics, discrete element method, and discontinuous deformation analysis methods have gradually developed, making it possible to simulate the instability deformation of dams. However, mesh-based methods have mesh distortion problems when dealing with large deformation problems, and the cost of re-meshing is too high. Therefore, they are only suitable for stability analysis before large deformation, and cannot evaluate the large deformation process after the instability of the dam. The particle-based method can handle large deformation problems well and can simulate and analyze the instability mechanism and large deformation behavior of landslide dams.

[0004] However, there are still some difficulties and challenges in the calculation of slope stability and large deformation of landslide dams, such as the characterization of the heterogeneous characteristics of the internal materials of the landslide dams, especially the influence of the rocks inside the landslide dams. In the existing simulations of landslide dams, the landslide dams are mostly regarded as homogeneous materials, and a single soil material is used to simulate their deformation behavior, which is inconsistent with the actual situation of particle sorting and different particle sizes generated during the accumulation and formation of the actual landslide dams. In addition, for the impact load of rolling stones and the moving load of vehicles during emergency disposal, such loads are usually equivalent to load boundaries in the current numerical simulations, and it is difficult to consider the dynamic coupling between vehicles and rolling stones and landslide dams, such as the influence of the shape and size of rolling stones, the location of occurrence, etc., and there is a lack of numerical simulation methods for the whole process of quantification of landslide dam damage, stability judgment, and subsequent large deformation calculation under such calculation loads. Under extreme loads such as secondary landslides, rockfall impacts and vehicle loads, whether the dam continues to block the river and maintain stability, or becomes unstable and then breaks, these processes involve the critical transformation of the dam disaster chain. At present, there is no unified standard for the critical judgment of the evolution of the landslide dam disaster chain. The existing disaster chain evolution judgment is mainly carried out through statistical analysis, mathematical models and refined models. The statistical analysis method is based on the landslide river blocking database to conduct big data analysis to determine whether to block the river, which is subjective. The mathematical model mainly uses a series of landslide river blocking critical judgment formulas, but there is no unified form for the judgment evaluation criteria and parameter selection. Refined models have gradually developed in recent years, such as SPH (smoothed particle hydrodynamics method), DEM (discrete element method), and MPM (material point method) simulation, but at present, such methods are insufficient due to insufficient consideration of mechanisms, such as less consideration of random distribution of blocks, particle sorting, and constitutive model optimization. Summary of the invention

[0005] The present invention is conducted to solve the above-mentioned problems, and its purpose is to provide a method and system for simulating large deformation of instability disaster of landslide dam under extreme working conditions, so as to solve the problems in actual engineering that large deformation of instability of landslide dam under extreme working conditions is difficult to simulate, critical process of landslide dam disaster is difficult to predict, dynamic loads such as rolling stones and vehicles are difficult to characterize, and soil and rock material modeling of landslide dam is overly simplified.

[0006] To achieve the above object, the technical solution of the method of the present invention is:

[0007] A method for simulating large deformation of a dam under extreme working conditions due to instability disasters comprises the following steps:

[0008] Step 1. Construct a 3D solid model of the dam, a 3D solid model of the terrain, a 3D solid model of the vehicle, a 3D solid model of the rolling stone, a water flow model, and a secondary landslide model respectively and discretize them into equidistant particle models; assign basic parameter values ​​to each particle and set the particle type;

[0009] Step 2. Construct a general constitutive model to characterize the fluidization phase change behavior of soil;

[0010] Step 3. Take the soil particles of the landslide dam, the stone particles of the landslide dam, the vehicle particles and the rolling stone particles as the central particles respectively, conduct particle contact judgment, simulate the deformation behavior of the central particles based on the constructed general constitutive model characterizing the fluidization phase change behavior of the soil, and couple and calculate the characteristic information of different central particles respectively;

[0011] Step 4. Visualize the characteristic information of each central particle obtained by calculation and control it by particle type to achieve material output classification.

[0012] Furthermore, in step 1, a plurality of real rocks are scanned in three dimensions to establish a rock database, and a three-dimensional solid model of the landslide dam with random positions, random shapes and specified rock content is generated in the landslide dam;

[0013] Acquire the contour lines or elevation point information of the established three-dimensional terrain to fit into a closed entity model, and generate a three-dimensional terrain entity particle model through a particle filling algorithm;

[0014] The vehicle 3D solid model, the rolling stone 3D solid model, the secondary landslide body model and the water flow solid model are established with high fidelity according to the actual model size and the vehicle 3D solid particle model, the rolling stone 3D solid particle model, the secondary landslide body particle model and the water flow solid particle model are generated respectively through the particle filling algorithm.

[0015] Furthermore, the step 1 includes landslide particles, water flow particles, terrain particles, dam particles and dynamic boundary particles, and the dam particles include dam soil particles and dam block stone particles.

[0016] The dynamic boundary particles include rolling stone particles, rock particles inside the dam, and vehicle particles.

[0017] Furthermore, the basic parameters set for the landslide particles in step 1 include: density, internal friction angle, cohesion, elastic modulus, Poisson's ratio, and friction coefficient;

[0018] The basic parameters for setting water flow particles include: density, viscosity;

[0019] The basic parameters for terrain particles include: density, stiffness, and friction coefficient;

[0020] The basic parameters set for dam particles include: density, internal friction angle, cohesion, elastic modulus, Poisson's ratio, and friction coefficient;

[0021] The basic parameters set for dynamic boundary particles include: density, stiffness, and friction coefficient.

[0022] Furthermore, the general constitutive model for characterizing the fluidization phase change behavior of soil in step 2 is:

[0023]

[0024] in, is the total stress; p solid is the spherical stress of the solid constitutive model; δ αβ is a piecewise function, α and β represent the vector direction of stress, when α=β, δ αβ The value is 1, otherwise it is 0; is the deviatoric stress of the solid constitutive model; p fluid is the constitutive pressure of the fluid; is the shear stress of the fluid constitutive structure; To characterize the stress before the soil of the dam fails, that is, the solid constitutive stress, its value is σ critical is the stress intensity value when the material is in the critical state, which can be obtained through geotechnical engineering tests. Its value is is the real-time shear strain rate of the soil in the dam; is the critical shear strain rate of the soil in the dam, which can be obtained through geotechnical engineering tests; critical is the spherical stress when the soil is in a critical state, is the shear stress when the soil is in a critical state.

[0025] Furthermore, the particle contact determination in step 3 includes:

[0026] The contact types of all particles are judged. If the particle radius is r, the influence domain of the particle is 2r. That is, the contact calculation is performed when the distance between two particles does not exceed 2r, and the contact effect between the two particles is calculated.

[0027] Furthermore, the step 3 simulates the deformation behavior of the central particle based on the constructed general constitutive model for characterizing the fluidization phase change behavior of the soil, including:

[0028] Taking the dam soil particle, landslide soil particle or water particle as the central particle i, the control equation is as follows:

[0029]

[0030]

[0031] Where: i is the density of the central particle i; t is the calculation time; m j is the mass of particle j; is the velocity difference between the central particle i and the surrounding particle j in the influence domain, i.e. The direction is β direction; D ij,βis a smooth kernel function, representing the weight value of all particles j in the influence domain centered on particle i in the β direction; x is the position coordinate of the base point, is the displacement of particle i in the β direction; is the velocity gradient of the central particle i, that is, the acceleration of particle i; is the stress tensor of particle i, is the stress tensor of particle j, is the pressure of particle j, is the shear stress of particle j, g α is the acceleration of gravity; α and β represent the vector direction of stress, which is a third-order tensor. Both α and β can correspond to the three directions of x, y, and z; D is the soil particle area of ​​the dam, L is the soil particle area of ​​the landslide, W is the water particle area, DB is the dynamic boundary area of ​​boulders, dam top vehicles, and rolling stones, and SB is the static boundary particle area of ​​the terrain.

[0032] Taking the block particle of the dam as the central particle k, the control equation is as follows:

[0033]

[0034]

[0035]

[0036] In the formula, ρ k is the density of the central particle k; is the velocity difference between the central particle k and the surrounding particles j in the influence domain, i.e. D kj,β The weight value of all particles j in the influence area centered on particle k in the β direction; is the displacement of particle k in the β direction; rock A has mass M A , speed V A , inertia tensor I A , angular velocity Ω A and the center of gravity R A ;m k is the mass of the central particle k; p k αβ is the pressure of particle k, τ k αβ is the shear stress of particle k, σ j αβ is the stress of particle j, f rock,j→k is the force exerted by the rest of the dam's rocks on particle k on rock A, f Vehicle,j→k is the force exerted by the vehicle on the dam top on particle k on the rock A, f debris,j→k is the force exerted by the rolling stone on particle k on the stone block A; r kis the center of gravity of particle k.

[0037] Taking the vehicle particle or the rolling stone particle k' as the central particle, the control equation is as follows:

[0038]

[0039]

[0040]

[0041] In the formula, ρ k' is the density of the central particle k'; is the velocity difference between the central particle k' and the surrounding particles j in the influence domain, i.e. D k'j,β is the weight value of all particles j in the influence area centered on particle k' in the β direction; is the displacement of particle k' in the β direction; m k' is the mass of the central particle k'; p k' αβ is the pressure of particle k', τ k' αβ is the shear stress of particle k', f rock,j→k is the force exerted by the rest of the dam's rocks on the k' particle on rock A, r k' is the center of gravity of the k' particle.

[0042] Furthermore, f rock,j→k 、f Vehicle,j→k 、f debris,j→k The following formula can be used for calculation:

[0043] f rock,j→k =f n,ij +f t,ij

[0044]

[0045]

[0046] In the formula, is the normal stiffness coefficient related to the elastic modulus, Poisson's ratio and particle radius, is the normal damping constant, e ij is the coefficient of restitution, k t,ij =2 / 7k n,ij is the tangential stiffness coefficient, γ n,ij =2 / 7γ n,ij is the tangential damping coefficient, δ ij =max(0,(d i +d j ) / 2-|rij |) is the intrusion distance between particles, which is used to characterize the degree of collision between particles, e ij is a unit vector, is the normal deformation rate. The tangential contact force is given by:

[0047]

[0048] Furthermore, step 4 includes: calculating the field variable information of each particle through the smooth particle fluid dynamics method, and the obtained information is digital text information, which is converted into a binary VTK file output for visualization, wherein the particle output of different partitions is controlled by the particle type, and material output classification can be realized.

[0049] On the other hand, the present invention provides a system for simulating large deformation of a dam under extreme working conditions due to instability disaster, comprising:

[0050] Particle model construction module: It is used to construct three-dimensional solid models of dam, terrain, vehicles, rocks, water flow and secondary landslide respectively and discretize them into equidistant particle models; assign basic parameter values ​​to each particle and set the particle type;

[0051] Constitutive model building module: It is used to build a general constitutive model to characterize the fluidization phase change behavior of soil;

[0052] Coupling calculation module: It is used to determine particle contact by taking soil particles of the landslide dam, rock particles of the landslide dam, vehicle particles and stone particles as the central particles, simulate the deformation behavior of the central particles based on the general constitutive model constructed to characterize the fluidization phase change behavior of the soil, and perform coupling calculations on the characteristic information of different central particles respectively;

[0053] Visualization output module: It is used to visualize the characteristic information of each central particle obtained by calculation, and control it through particle type to realize material output classification.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] (1) The present invention breaks through the limitations of traditional methods that are too simplified when calculating the dynamic load of a dam and that the grid method is not suitable for processing large deformation calculations. A universal constitutive model that can characterize the behavior of soil, fluid and soil phase change is proposed. The fluid-solid coupling mechanism between landslides, water flows and dams is considered, and a refined numerical simulation method for large deformation of dam instability disasters is established that considers the combined effects of landslide disaster chain impact, vehicle load and rockfall impact. This method can predict the stability of dams under extreme working conditions and the subsequent large deformation destruction process.

[0056] (2) The present invention solves the problem of unclear critical transformation conditions and inconsistent judgment criteria for the disaster chain of landslide-dam disasters, and proposes a method for predicting the critical transformation process of landslide-dam disasters under extreme working conditions. Considering the impact of secondary landslides, rock rolling and vehicle loads on existing landslides, a "landslide-rock rolling and vehicle-dam" coupled large deformation calculation model is established. The method can predict the disaster chain transformation process of secondary landslides, rock rolling and vehicle loads that induce the instability and collapse of landslide dams or further blockage of the river, revealing the mechanism by which secondary landslides, rock rolling and vehicle loads promote or delay the instability of landslide dams, and can provide a tool for risk assessment and early warning of instability of landslide bodies.

[0057] (3) The present invention avoids the assumption of traditional methods that landslide rockfall impact loads and vehicle loads are equivalent to concentrated force boundaries. It establishes a real landslide, rockfall impact and vehicle movement load model, calculates the dynamic response and deformation characteristics of the landslide dam under dynamic loads, and truly reconstructs the damage evolution process of the plastic zone inside the landslide dam under extreme loads. This method solves the engineering problem of difficult safety assessment of landslide dams under extreme working conditions.

[0058] (4) The present invention breaks through the limitations of ignoring the influence of real rocks in the traditional dam modeling process, or using generalized models in the dam modeling process, which are highly subjective, have uncertainties and are divorced from engineering practice. This patent provides a high-fidelity dam modeling method that takes into account the distribution of rocks. By randomly arranging rocks in the dam, a three-dimensional model of the dam that takes into account the real rock shape and different rock contents is constructed, ultimately forming a high-fidelity dam modeling method. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0060] Figure 1 Schematic diagram of a particle model in an embodiment of the present invention.

[0061] Figure 2 It is a schematic diagram of a high-fidelity model of a barrier dam containing random real rocks according to an embodiment of the present invention.

[0062] Figure 3 It is a schematic diagram of the coupling contact between landslide, water flow, terrain, dam, rolling stone and vehicle in an embodiment of the present invention.

[0063] Figure 4 It is a schematic diagram of the evolution of the sand column collapse velocity field and the slope line comparison at different times according to an embodiment of the present invention.

[0064] Figure 5 It is a schematic diagram of the evolution of the sand column collapse velocity field and the slope line comparison at different times according to an embodiment of the present invention.

[0065] Figure 6 It is a schematic diagram of the layout of the indoor impact test device according to an embodiment of the present invention.

[0066] Figure 7 Schematic diagram of the velocity field evolution process of sand column particles impacting the baffle according to an embodiment of the present invention.

[0067] Figure 8 This is a schematic diagram of the comparison results of the impact force of the sand column impacting the baffle in an embodiment of the present invention.

[0068] Fig. 9 This is a schematic diagram of the falling process of a 15m high small rolling stone according to an embodiment of the present invention.

[0069] Fig.10 This is a schematic diagram of the falling process of a small boulder 40m high according to an embodiment of the present invention.

[0070] Fig.11 This is a schematic diagram of the falling process of a 15m high boulder according to an embodiment of the present invention.

[0071] Fig.12 Schematic diagram of a refined model of a vehicle tire according to an embodiment of the present invention.

[0072] Fig.13 It is a schematic diagram of the large deformation process of the barrier dam under the cyclic load of vehicles in an embodiment of the present invention.

[0073] Fig.14 This is a schematic diagram of the critical transformation of the disaster chain caused by a secondary landslide impacting a landslide dam according to an embodiment of the present invention.

[0074] Fig.15 It is a schematic diagram of the whole process of landslide triggering - induced surge - impacting the barrier dam - dam instability and collapse according to an embodiment of the present invention. DETAILED DESCRIPTION

[0075] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0076] Example 1

[0077] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0078] The present invention provides a method for simulating large deformation of a dam under extreme working conditions due to instability disaster, comprising the following steps:

[0079] Step 1. Construct a 3D solid model of the dam, a 3D solid model of the terrain, a 3D solid model of the vehicle, a 3D solid model of the rolling stone, a water flow model, and a secondary landslide model respectively and discretize them into equidistant particle models; assign basic parameter values ​​to each particle and set the particle type;

[0080] In step 1, a plurality of real rocks are 3D scanned to establish a rock database, and a 3D solid model of the dam with random positions, random shapes and specified rock content is generated in the dam; specifically, the modeling of the rocks inside the dam is performed, considering the real shape and content of the rocks, and a handheld 3D laser scanner is used to perform 3D scanning on a plurality of real rocks to establish a rock database, such as Figure 1 (a) is shown. The block stone obtained by three-dimensional scanning is a solid model. The particle sampling algorithm is used to discretize the solid model into a particle model. The particle sampling algorithm process is as follows: set a cube calculation domain, the entire block stone model is included in the cube, set a seed point inside the block stone area, and then set the particle spacing information to continuously generate particles. The block stone stl model boundary is used as the judgment boundary. When the generated particles are inside the block stone stl model boundary, the particles are generated normally. If they are outside the boundary, the generated particles are deleted. Finally, the following can be obtained: Figure 1 (b) shows the particle model. The accuracy of the block stone model can be controlled by adjusting the particle spacing, such as Figure 1 As shown in (c). After the real rock shape is obtained, the real dam model with random position, random shape and specified rock content is considered to be generated in the dam. For the random position of the rock, a sphere can be randomly generated in the dam to ensure that the rock is embedded in the sphere position. For the random shape, it can be achieved by randomly extracting the numbered rocks in the rock database. For the specified rock content, the content of the rock can be calculated by repeatedly generating random positions and random shapes for each rock inside the dam. When the expected stone content is reached, the generation of the rock can be stopped, as shown in Figure 2 shown.

[0081] The contour lines or elevation point information of the established three-dimensional terrain is obtained and fitted into a closed entity model, and a three-dimensional terrain entity particle model is generated through a particle filling algorithm; specifically: the contour lines or elevation point information of the established three-dimensional terrain is required, and this information is imported into the modeling software to fit into a closed entity model, and then the three-dimensional terrain entity particle model is generated through the above-mentioned particle filling algorithm, and the output is a VTK format file, which is convenient for subsequent import into the algorithm program.

[0082] The vehicle 3D solid model, the rolling stone 3D solid model, the secondary landslide body model and the water flow solid model are built into high-fidelity models according to the actual model size and the vehicle 3D solid particle model, the rolling stone 3D solid particle model, the secondary landslide body particle model and the water flow solid particle model are generated respectively through the particle filling algorithm. Specifically, a high-fidelity model is built in Rhino or CAD according to the actual model size, and then the above-mentioned particle filling algorithm is used to fill the model into a solid particle model and output it as a VTK format file for subsequent import into the algorithm system for calculation.

[0083] Step 2. Construct a general constitutive model to characterize the fluidization phase change behavior of soil;

[0084] The landslide and the dam of the present invention are both soil bodies, and the same constitutive model is used, but the model parameters are different. Taking the soil body of the dam as an example, the dam maintains a solid form in the stable stage. When the dam is unstable under the impact of extreme loads such as the landslide disaster chain, coupled with the loading of the reservoir water in front of the dam, the dam will collapse and move downstream, showing the characteristics of fluid motion. After blocking the river, the dam continues to show solid characteristics. However, after the existing solid constitutive model such as the Drucker-Prager model reaches the yield state, the soil enters the plastic flow state, and the strain rate change in the model is always 0, but at this time the soil presents the characteristics of fluidization motion, and its stress changes with strain, that is, the strain rate is not 0, so the traditional Drucker-Prager solid constitutive model cannot reflect this characteristic. The fluid constitutive model is a rate-dependent constitutive model, which can reflect the evolution process of strain rate with stress, but the fluid constitutive model is mainly suitable for high-speed particle flow, and cannot model the process of the dam slope becoming unstable and entering yield, that is, it cannot predict the critical sliding start and sliding surface position of the dam slope. Therefore, it is necessary to propose a universal constitutive model for the whole process that is suitable for characterizing the fluidization phase change behavior of the soil in the landslide dam. The model needs to have the advantages of both the solid constitutive model and the fluid constitutive model. Therefore, this patent proposes a universal constitutive model that can simulate the evolution of the whole process of the static solid state, triggered motion state and accumulation solid state of the soil in the landslide dam. The parameters of the model can be determined by simple geotechnical tests, and the critical conditions of phase change are determined by the yield condition and strain rate of the soil. Its advantage is that it can automatically realize the smooth conversion of solid and fluid behaviors in the two stages before and after instability, and can predict the fluidization phase change behavior of the soil in the landslide dam. The total stress format of stress decomposition adopted by the model is as follows:

[0085]

[0086] In the formula, σ total is the total stress, σ solid To characterize the stress before the soil of the dam fails, that is, the solid constitutive stress, σ fluid To characterize the stress after the soil of the dam is unstable, that is, the fluid constitutive stress, α and β represent the vector direction of the stress, p solidis the spherical stress of the solid constitutive law, and the formula 1 / 3σ αβ δ αβ Solve, p critical is the spherical stress when the soil is in a critical state, is the deviatoric stress of the solid constitutive model, s critical is the deviatoric stress when the soil is in a critical state, which can be expressed by the solid constitutive equation Find, p fluid is the pressure of the fluid, is the shear stress of the fluid constitutive equation, which can be expressed as Solve, η is the equivalent viscosity, is the absolute value of the shear strain rate of the fluid constitutive part, which can be obtained by Calculated, is the critical shear strain rate of the soil in the dam, which can be obtained through the annular shear test. When the shear strain rate of the soil exceeds the critical shear strain rate, it exhibits fluid motion characteristics. fluid is the constitutive pressure of the fluid, which can be obtained from the equation of state Find, where c s is the speed of sound, ρ0 is the initial density, γ is the shear strain, ρ i is the temporary density calculated at each moment. When the dam does not fail, that is, the soil does not yield and the shear strain rate does not exceed the critical shear strain rate of the soil, the condition is satisfied. At this time, the soil of the dam shows solid morphology. When the dam is unstable, that is, the soil yields and the shear strain rate exceeds the critical shear strain rate of the soil, the condition is met. At this time, the soil of the dam shows the characteristics of fluid movement, that is, the stress of the solid constitutive part remains unchanged, and the stress of the fluid part changes with the shear strain rate.

[0087] Step 3. Take the soil particles of the landslide dam, the stone particles of the landslide dam, the vehicle particles and the rolling stone particles as the central particles respectively, conduct particle contact judgment, simulate the deformation behavior of the central particles based on the constructed general constitutive model characterizing the fluidization phase change behavior of the soil, and couple and calculate the characteristic information of different central particles respectively;

[0088] The coupled contact between landslide, water flow, terrain, dam, rockfall and vehicle is as follows: Figure 3 As shown in the figure, in actual engineering, we are more concerned about the safety of the dam itself, so we mainly take the dam as the research object, and there are five main types of particles considered, namely, the landslide particle area, denoted by L; the water flow particle area, denoted by W; the terrain particle area is the static boundary, denoted by SB; the dam particle area, denoted by D; the rolling stone, the dam internal stone and the vehicle particle area belong to the dynamic boundary, which are uniformly denoted by DB.

[0089] ① Taking soil particle i of the dam as the center, the stress between soil particles is calculated by the proposed general constitutive model. The dam contains soil and rocks. The soil is calculated by the constitutive model to calculate the stress-strain information, and the rocks are simulated by the SPH dynamic boundary. The main contact relationships are: soil particles of the dam are in contact with their own soil particles, direct contact with landslide soil particles, soil particles of the dam are in contact with dynamic boundary particles such as their own rocks, vehicles on the dam top, and external rolling stones, soil particles of the dam are in contact with static boundary particles of the terrain, and soil particles of the dam are in contact with reservoir water particles. The control equation of soil particle i of the dam is as follows, which can calculate the particle acceleration and velocity, and then solve the particle displacement and position, etc.:

[0090]

[0091] Where: i is the density of the central particle i; t is the calculation time; m j is the mass of particle j; is the velocity difference between the central particle i and the surrounding particle j in the influence domain, i.e. The direction is β direction; D ij,β is a smooth kernel function, representing the weight value of all particles j in the influence domain centered on particle i in the β direction; x is the position coordinate of the base point, is the displacement of particle i in the β direction; is the velocity gradient of the central particle i, that is, the acceleration of particle i; is the stress tensor of particle i, is the stress tensor of particle j, is the pressure of particle j, is the shear stress of particle j, g α is the acceleration of gravity; α and β represent the vector direction of stress, which is a third-order tensor. Both α and β can correspond to the three directions of x, y, and z; D is the soil particle area of ​​the dam, L is the soil particle area of ​​the landslide, W is the water particle area, DB is the dynamic boundary area of ​​boulders, dam top vehicles, and rolling stones, and SB is the static boundary particle area of ​​the terrain.

[0092] The information calculation of landslide soil particles is similar to that of dam particles. Five types of contact relationships are considered, namely: contact between landslide soil particles and their own soil particles, contact with dam soil particles, contact with the static boundary of the terrain, contact with the dynamic boundary of the rocks inside the dam, and contact with water flow. The calculation formula is similar to formula (2) and (3).

[0093] ② For rolling stones, vehicle loads, and rocks inside the dam, the algorithms are similar and are all calculated as movable boundaries. For rock particles, with the dam rock particles as the center, there are five main contact relationships during the movement of the rock, namely: contact between the rock and the dam soil particles, direct contact between the rock and the landslide soil particles, contact with the dynamic boundaries such as other rocks, rolling stones, and vehicles on the dam top, contact with the static boundaries of the terrain, and contact with water particles. Assuming that the rock A is composed of a series of corresponding particles k, the particle information is calculated based on the following formula, and the particle acceleration and velocity can be calculated, and then the particle displacement and position can be solved:

[0094]

[0095]

[0096] In the formula, rock A has mass M A , speed V A , inertia tensor I A , angular velocity Ω A and the center of gravity R A ; Calculate the vector at each time step; D is the dam soil particle area, L is the landslide soil particle area, W is the water flow particle area, SB is the terrain static boundary particle area, DB is the block stone, dam top vehicle, rolling stone particle dynamic boundary area, f rock,j→k is the force exerted by the rest of the dam's rocks on particle k on rock A, f Vehicle,j→k is the force exerted by the vehicle on the dam top on particle k on the rock A, f debris,j→k is the force exerted by the rolling stone on particle k on the block A, f rock,j→k 、f Vehicle,j→k 、f debris,j→k The following formula can be used for calculation, with f rock,j→k Calculation example:

[0097] f rock,j→k =f n,ij +f t,ij (7)

[0098]

[0099] In the formula The normal stiffness coefficient is related to the elastic modulus, Poisson's ratio and particle radius, is the normal damping constant, e ij is the coefficient of restitution, k t,ij =2 / 7k n,ij . is the tangential stiffness coefficient, γ n,ij =2 / 7γ n,ij is the tangential damping coefficient, δ ij =max(0,(d i +dj ) / 2-|r ij |) is the intrusion distance between particles, which is used to characterize the degree of collision between particles. ij is a unit vector, is the normal deformation rate. The tangential contact force is given by:

[0100]

[0101] ③ The calculation algorithms for vehicles and rolling stones are similar. In the algorithm framework of this patent, for vehicle movement, the deformation and dynamic response calculation of the dam under the action of vehicle moving load is realized by giving the vehicle speed information. For rolling stones, an initial velocity and incident direction need to be set. Then the rolling stones move under the action of gravity and eventually impact the dam body, causing the dam to deform or even become unstable and collapse.

[0102] Taking vehicle particle i as the center, its main contact relationship is: vehicle particle contacts with soil particles of the dam and with stone particles of the dam. The contact between the vehicle and the landslide, rolling stones and water flow is not considered. The particle information is calculated based on the following formula, and the particle acceleration and velocity can be calculated, and then the particle displacement, position, etc. can be solved.

[0103]

[0104] In the formula, ρ k is the density of the central particle k; is the velocity difference between the central particle k and the surrounding particles j in the influence domain, i.e. D kj,β The weight value of all particles j in the influence area centered on particle k in the β direction; is the displacement of particle k in the β direction; rock A has mass M A , speed V A , inertia tensor I A , angular velocity Ω A and the center of gravity R A ;m k is the mass of the central particle k; p k αβ is the pressure of particle k, τ k αβ is the shear stress of particle k, σ j αβ is the stress of particle j, f rock,j→k is the force exerted by the rest of the dam's rocks on particle k on rock A, f Vehicle,j→k is the force exerted by the vehicle on the dam top on particle k on the rock A, f debris,j→k is the force exerted by the rolling stone on particle k on the stone block A; r k is the center of gravity of particle k.

[0105] Taking the rolling stone particle k as the center, its main contact relationship is: the rolling stone particle contacts with the soil particles of the landslide dam and contacts with the block stone particles of the landslide dam. The contact between the rolling stone particles and the landslide body, vehicles and water flow is not considered. Therefore, the information of the rolling stone particles can also be calculated according to equations (11), (12) and (13).

[0106] ④ For water flow particles, the pressure between water particles is calculated using the SPH weak compressible algorithm with water particle i as the center. There are five main contact relationships, namely: water particles and their own water particles, dam soil particles, landslide soil particles, dynamic boundaries of blocks inside the dam, and static boundaries of terrain. The particle information can be calculated based on the following formula, and the particle acceleration and velocity can be calculated, and then the particle displacement and position can be solved:

[0107]

[0108] Where: i is the density of the central particle i; t is the calculation time; m j is the mass of particle j; is the velocity difference between the central particle i and the surrounding particle j in the influence domain, i.e. The direction is β direction; D ij,β is a smooth kernel function, representing the weight value of all particles j in the influence domain centered on particle i in the β direction; x is the position coordinate of the base point, is the displacement of particle i in the β direction; is the velocity gradient of the central particle i, that is, the acceleration of particle i; is the stress tensor of particle i, is the stress tensor of particle j, is the pressure of particle j, which can be obtained through the state equation, is the shear stress of particle j, which can be expressed by Interpolation is obtained, g α is the acceleration of gravity; α and β represent the vector direction of stress, which is a third-order tensor. Both α and β can correspond to the three directions of x, y, and z; D is the soil particle area of ​​the dam, L is the soil particle area of ​​the landslide, W is the water particle area, DB is the dynamic boundary area of ​​boulders, dam top vehicles, and rolling stones, and SB is the static boundary particle area of ​​the terrain.

[0109] Step 4. Visualize the characteristic information of each central particle obtained by calculation and control it by particle type to achieve material output classification.

[0110] The field variable information of each particle, such as stress, strain, displacement, velocity, acceleration, etc., is calculated by the smooth particle fluid dynamics method. The obtained information is digital text information, which is converted into binary VTK file output for visualization. The particle output of different partitions is controlled by particle type, which can realize material output classification. Therefore, binary files containing particle information such as dam, landslide, and rolling stone can be output respectively. Such files can be visualized in some general open source software such as Paraview.

[0111] Example 1

[0112] In this example, a two-dimensional sand column collapse test was carried out for the unstable accumulation process of the dam. The sand column was 0.2m long and 0.1m high. It collapsed naturally under the action of gravity. The particle spacing of the sand column was set to 1mm. The material parameters of the sand column were as follows: density was 2040kg / m 3 , elastic modulus E=5.84Mpa, Poisson's ratio is 0.3, internal friction angle is 21.9°, and cohesion is 0.

[0113] Figure 4 The evolution of the collapse velocity field of the sand column at different times and the comparison of the particle flow contours are given. It can be seen that the numerical simulation results of this study are in good agreement with the experimental results, indicating that the SPH model established by this algorithm can predict the large deformation behavior of granular materials. When the sand column reaches equilibrium, the final accumulation shape is as follows Figure 5 As shown, according to its cumulative plastic strain distribution, an obvious shear band interface can be observed. It can be seen that the undisturbed area obtained in this study is basically consistent with the experimental results, which further proves the accuracy of the current method.

[0114] Example 2

[0115] This embodiment aims at the process of secondary landslide directly impacting the barrier dam, and compares the indoor impact test results to verify the reliability of the model in calculating the impact response of the landslide evolution process. Figure 6 The indoor impact test device used, where (a) is a real-life picture of the test device, and (b) is a schematic diagram of the geometric parameters of the test device. The inclined chute has an inclination angle of 45°, a length of 0.5m, a width of 0.3m, and a distance of 1.8m from the front of the sand column to the wall. At the initial moment, after the wooden box door is opened, the fine sand moves along the chute under the action of gravity. A measuring instrument that can record the impact force value is installed at the bottom of the chute. After the fine sand collides with the measuring instrument, it will gradually stop. The density of fine sand is 1379kg / m 3 , the internal friction angle is 35°, and the cohesion is 0. A landslide impact baffle model is established, and the particle spacing is set to 0.01m.

[0116] Figure 7The velocity field evolution process of the sand column impacting the baffle at different times is given. After being released, the sand column evolves downward, then hits the rigid baffle and accumulates in front of the baffle. When the sand accumulation reaches the top of the baffle, part of the sand overflows from Figure 4 It can be seen that the simulation results are similar to the experimental phenomena. Figure 8 This is a comparison of the impact force time history curves obtained from the indoor test and numerical simulation. Before the sand column soil collides with the baffle, the impact force is always 0. As the sand and the baffle collide at T = 0.71s, the sand continues to accumulate in front of the baffle, and the impact force on the baffle gradually increases and reaches a peak. Subsequently, due to the overflow of sand, the impact force of the baffle will decrease to a certain extent. Figure 8 It shows that the time point of landslide impact on the baffle calculated in this study is basically consistent with the test. For the peak impact force, the peak impact force on the baffle in the test is 188.6N, and the peak impact force obtained in this study is 188.2N, which is slightly lower than the test value. The relative error of the peak impact force is 0.2%. Overall, it can be seen that the impact force obtained in this study is in good agreement with the test results.

[0117] Example 3

[0118] This embodiment considers different rockfall volumes and different rockfall initial heights to calculate the large deformation process of the dam slope caused by rockfall impact, and the figure shows the plastic strain.

[0119] Fig. 9 The dynamic process of a rockfall with a volume of 0.5m*0.5m*0.5m impacting the dam at a height of 15m is given. It can be seen that the top of the barrier dam shows local damage, the plastic zone of the dam slope increases slightly, and the dam body remains basically stable.

[0120] Fig.10 The dynamic process of a rockfall with a volume of 0.5m*0.5m*0.5m impacting the dam at a height of 40m is given. It can be seen that local damage occurs on the crest of the barrier dam, and the range of the plastic zone of the dam slope increases significantly compared with the 15m working condition. The plastic zone gradually penetrates over time and undergoes large deformation, but the deformation rate is slow, indicating that the higher the initial height of the rockfall, the greater the kinetic energy of the rockfall when it falls to the dam crest. At this time, the more serious the local damage to the dam crest is, and the larger the range of the plastic zone is.

[0121] Fig.11 The dynamic process of a rockfall of 1.5m*1.5m*1.5m hitting a dam at a height of 15m is given. It can be seen that a large-scale damage occurs on the top of the barrier dam, and the plastic zone of the dam slope is connected, showing overall instability and damage. At this time, the slope of the barrier dam cannot remain stable. After the instability of the barrier dam, it evolves into a chain of flood disasters. This shows that the patented algorithm can predict the transformation process of the disaster chain that induces the instability and collapse of the barrier dam or further blockage of the river due to rockfall impact loads, and can provide a tool for risk assessment and early warning of instability of the barrier dam.

[0122] Example 4

[0123] This embodiment performs high-fidelity modeling on different emergency response vehicles, such as Fig.12 shown. Fig.13 The distribution of plastic zone of the dam slope under vehicle cyclic load is given. Fig.13 It shows that with the increase of vehicle load cycle times, the plastic zone of the dam slope increases significantly, and the dam is likely to become unstable. This shows that the patented algorithm can predict the deformation and destruction process of the dam under complex loads such as vehicles.

[0124] Example 5

[0125] This example is a calculation of the transformation process of the disaster chain induced by the impact of the secondary landslide on the dam. The secondary landslide, dam, and terrain boundary particle model are established. Fig.14 It can be seen that, on the one hand, this case shows that the general constitutive structure adopted by the algorithm of this patent can better calculate the whole process of landslide initiation-movement-accumulation, and reasonably characterize the interaction between the landslide and the terrain boundary; on the other hand, after the secondary landslide hits the landslide dam, it will cause the volume of the landslide dam to increase, and the height of the landslide dam to increase, making the landslide dam less likely to collapse, affecting the critical transformation process of the landslide dam disaster chain, indicating that the algorithm of this patent can simultaneously calculate and determine the critical transformation process of the disaster chain of the landslide blocking the river to form a landslide dam.

[0126] Example 6

[0127] This example simulates the whole process of landslide-induced surge impact-induced instability and large deformation of the dam. Fig.15 The whole process of landslide triggering, induced surge, impact on the barrier dam, and dam instability and collapse is shown in the figure, in which the landslide and the dam are simulated using the universal constitutive model of this patent. Fig.15 (a) to (e) show that this algorithm can reasonably characterize the coupling contact relationship between landslide soil, terrain, water flow, and landslide dam. From the movement behavior of the landslide body, it can be seen that this patent can predict the entire process of the landslide soil from the triggered quasi-static state to the moving state and then to the accumulated solid state. From the movement behavior of the water flow, it can be seen that this patent can better capture the fluid-solid coupling behavior between the landslide-water body-landslide dam. From the instability and failure behavior of the landslide dam, it can be seen that this patent can realize the refined numerical simulation of the large deformation of the instability disaster of the landslide dam under extreme loads such as the impact of the landslide disaster chain, and realize the accurate prediction of the plastic failure zone of the landslide dam.

[0128] Example 7

[0129] This embodiment provides a system for simulating large deformation of a dam under extreme working conditions due to instability disasters, including:

[0130] Particle model construction module: It is used to construct three-dimensional solid models of dam, terrain, vehicles, rocks, water flow and secondary landslide respectively and discretize them into equidistant particle models; assign basic parameter values ​​to each particle and set the particle type;

[0131] Constitutive model building module: It is used to build a general constitutive model to characterize the fluidization phase change behavior of soil;

[0132] Coupling calculation module: It is used to determine particle contact by taking soil particles of the landslide dam, rock particles of the landslide dam, vehicle particles and stone particles as the central particles, simulate the deformation behavior of the central particles based on the general constitutive model constructed to characterize the fluidization phase change behavior of the soil, and perform coupling calculations on the characteristic information of different central particles respectively;

[0133] Visualization output module: It is used to visualize the characteristic information of each central particle obtained by calculation, and control it through particle type to realize material output classification.

[0134] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0135] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0136] Other parts not described in detail are all prior art.

Claims

1. A method for simulating large deformation of a dam under extreme working conditions due to instability disaster, characterized in that: The steps include: Step 1. Construct a 3D solid model of the dam, a 3D solid model of the terrain, a 3D solid model of the vehicle, a 3D solid model of the rolling stone, a water flow model, and a secondary landslide model respectively and discretize them into equidistant particle models; assign basic parameter values ​​to each particle and set the particle type; Step 2. Construct a general constitutive model to characterize the fluidization phase change behavior of soil; Step 3. Take the soil particles of the landslide dam, the stone particles of the landslide dam, the vehicle particles and the rolling stone particles as the central particles respectively, conduct particle contact judgment, simulate the deformation behavior of the central particles based on the constructed general constitutive model characterizing the fluidization phase change behavior of the soil, and couple and calculate the characteristic information of different central particles respectively; Step 4. Visualize the characteristic information of each central particle obtained by calculation and control it by particle type to achieve material output classification.

2. The method for simulating large deformation of a dam under extreme working conditions due to instability disaster as claimed in claim 1, characterized in that: In the step 1, a plurality of real rocks are three-dimensionally scanned to establish a rock database, and a three-dimensional solid model of the landslide dam with random positions, random shapes and specified rock content is generated in the landslide dam; Acquire the contour lines or elevation point information of the established three-dimensional terrain to fit into a closed entity model, and generate a three-dimensional terrain entity particle model through a particle filling algorithm; The vehicle 3D solid model, the rolling stone 3D solid model, the secondary landslide body model and the water flow solid model are established with high fidelity according to the actual model size and the vehicle 3D solid particle model, the rolling stone 3D solid particle model, the secondary landslide body particle model and the water flow solid particle model are generated respectively through the particle filling algorithm.

3. The method for simulating large deformation of a dam under extreme working conditions due to instability disaster as claimed in claim 1, characterized in that: The step 1 includes landslide soil particles, water flow particles, terrain particles, dam soil particles and dynamic boundary particles; the dynamic boundary particles include rolling stone particles, dam block stone particles and vehicle particles.

4. The method for simulating large deformation of a dam under extreme working conditions due to instability disaster as claimed in claim 3, characterized in that: In step 1, the basic parameters of the landslide soil particles are set to include: density, internal friction angle, cohesion, elastic modulus, Poisson's ratio, and friction coefficient; The basic parameters for setting water flow particles include: density, viscosity; The basic parameters set for terrain particles include: density, elastic modulus, Poisson's ratio, and friction coefficient; The basic parameters set for the soil particles of the dam include density, internal friction angle, cohesion, elastic modulus, Poisson's ratio, and friction coefficient; The basic parameters set for dynamic boundary particles include: density, elastic modulus, Poisson's ratio, and friction coefficient.

5. The method for simulating large deformation of a dam under extreme working conditions due to instability disaster as claimed in claim 1, characterized in that: The general constitutive model for characterizing the fluidization phase change behavior of soil in step 2 is: in, is the total stress; p solid is the spherical stress of the solid constitutive model; δ αβ is a piecewise function, α and β represent the vector direction of stress, when α=β, δ αβ The value is 1, otherwise it is 0; is the deviatoric stress of the solid constitutive model; p fluid is the constitutive pressure of the fluid; is the constitutive shear stress of the fluid; To characterize the stress before the soil of the dam fails, that is, the solid constitutive stress, its value is σ critical is the stress intensity value when the material is in the critical state, which can be obtained through geotechnical engineering tests. Its value is is the real-time shear strain rate of the soil in the dam; is the critical shear strain rate of the soil in the dam, which can be obtained through geotechnical engineering tests; critical is the spherical stress when the soil is in a critical state, is the shear stress when the soil is in a critical state.

6. The method for simulating large deformation of a dam under extreme working conditions due to instability disaster as claimed in claim 1, characterized in that: The particle contact determination in step 3 includes: The contact types of all particles are judged. If the particle radius is r, the influence domain of the particle is 2r. That is, the contact calculation is performed when the distance between two particles does not exceed 2r, and the contact effect between the two particles is calculated.

7. The method for simulating large deformation of a dam under extreme working conditions due to instability disaster as claimed in claim 1, characterized in that: The step 3 simulates the deformation behavior of the central particle based on the constructed general constitutive model for characterizing the fluidization phase change behavior of the soil, including: Taking the dam soil particle, landslide soil particle or water particle as the central particle i, the control equation is as follows: Where: i is the density of the central particle i; t is the calculation time; m j is the mass of particle j; is the velocity difference between the central particle i and the surrounding particle j in the influence domain, i.e. The direction is β direction; D ij,β is a smooth kernel function, representing the weight value of all particles j in the influence domain centered on particle i in the β direction; x is the position coordinate of the base point, is the displacement of particle i in the β direction; is the velocity gradient of the central particle i, that is, the acceleration of particle i; is the stress tensor of particle i, is the stress tensor of particle j, is the pressure of particle j, is the shear stress of particle j, g α is the acceleration of gravity; α and β represent the vector direction of stress, which is a third-order tensor. Both α and β can correspond to the three directions of x, y, and z; D is the soil particle area of ​​the dam, L is the soil particle area of ​​the landslide, W is the water particle area, DB is the dynamic boundary area of ​​the block stone, dam top vehicle, and rolling stone particles, and SB is the static boundary particle area of ​​the terrain; Taking the block particle of the dam as the central particle k, the control equation is as follows: In the formula, ρ k is the density of the central particle k; is the velocity difference between the central particle k and the surrounding particles j in the influence domain, i.e. D kj,β The weight value of all particles j in the influence area centered on particle k in the β direction; is the displacement of particle k in the β direction; rock A has mass M A , speed V A , inertia tensor I A , angular velocity Ω A and the center of gravity R A ;m k is the mass of the central particle k; p k αβ is the pressure of particle k, τ k αβ is the shear stress of particle k, σ j αβ is the stress of particle j, f rock,j→k is the force exerted by the rest of the dam's rocks on particle k on rock A, f Vehicle,j→k is the force exerted by the vehicle on the dam top on particle k on the rock A, f debris,j→k is the force exerted by the rolling stone on particle k on the stone block A; r k is the center of gravity of particle k; Taking the vehicle particle or the rolling stone particle k' as the central particle, the control equation is as follows: In the formula, ρ k' is the density of the central particle k'; is the velocity difference between the central particle k' and the surrounding particles j in the influence domain, that is D k'j,β is the weight value of all particles j in the influence area centered on particle k' in the β direction; is the displacement of particle k' in the β direction; m k' is the mass of the central particle k'; p k' αβ is the pressure of particle k', τ k' αβ is the shear stress of particle k', f rock,j→k' is the force exerted by the rest of the dam's rocks on the k' particle on rock A, r k' is the center of gravity of the k' particle.

8. The method for simulating large deformation of a dam under extreme working conditions due to instability disaster as claimed in claim 7, characterized in that: f rock,j→k 、f Vehicle,j→k 、f debris,j→k The following formula can be used for calculation: f rock,j→k =f n,ij +f t,ij In the formula, is the normal stiffness coefficient related to the elastic modulus, Poisson's ratio and particle radius, is the normal damping constant, e ij is the coefficient of restitution, k t,ij =2 / 7k n,ij is the tangential stiffness coefficient, γ n,ij =2 / 7γ n,ij is the tangential damping coefficient, δ ij =max(0,(d i +d j ) / 2-|r ij |) is the intrusion distance between particles, which is used to characterize the degree of collision between particles, e ij is a unit vector, is the normal deformation rate, and the tangential contact force is given by:

9. The method for simulating large deformation of a dam under extreme working conditions due to instability disaster as claimed in claim 7, characterized in that: The step 4 includes: calculating the field variable information of each particle through the smooth particle fluid dynamics method, and the obtained information is digital text information, which is converted into a binary VTK file output for visualization, wherein the particle output of different partitions is controlled by the particle type, and material output classification can be realized.

10. A simulation system for large deformation of instability disaster of landslide dam under extreme working conditions, characterized in that: include: Particle model construction module: It is used to construct three-dimensional solid models of dam, terrain, vehicles, rocks, water flow and secondary landslide respectively and discretize them into equidistant particle models; assign basic parameter values ​​to each particle and set the particle type; Constitutive model building module: It is used to build a general constitutive model to characterize the fluidization phase change behavior of soil; Coupling calculation module: It is used to determine particle contact by taking soil particles of the landslide dam, rock particles of the landslide dam, vehicle particles and stone particles as the central particles, simulate the deformation behavior of the central particles based on the general constitutive model constructed to characterize the fluidization phase change behavior of the soil, and perform coupling calculations on the characteristic information of different central particles respectively; Visualization output module: It is used to visualize the characteristic information of each central particle obtained by calculation, and control it by particle type to realize material output classification; The system for simulating large deformation caused by instability disaster of a dam under extreme working conditions is used to execute the steps in the method for simulating large deformation caused by instability disaster of a dam under extreme working conditions described in any one of claims 1 to 9.

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