CN-122020818-A - Seismic landslide large deformation overall process simulation method based on grid isolation technology

CN122020818ACN 122020818 ACN122020818 ACN 122020818ACN-122020818-A

Abstract

The invention discloses a method for simulating the whole process of large deformation of an earthquake landslide based on a grid isolation technology, and relates to the technical field of geotechnical engineering. According to the invention, a separated background grid and multi-medium model comprising a safety isolation belt is constructed based on a second-order convection particle subdomain interpolation object particle method, and a strain-driven soft hardening coupling constitutive mechanism is utilized to carry out dynamic analysis on the earthquake landslide, so that flexible input of earthquake waves at the isolation belt and anti-drift of a substrate are realized, and the complete evolution process from non-drainage shearing cracking to large-deformation friction accumulation of the landslide can be accurately simulated. The method effectively eliminates wave reflection interference of the dynamic boundary and numerical drift of long-lasting integral, realizes actual physical reproduction of the whole process from cracking to friction accumulation of the landslide, ensures more accurate and stable calculation of large deformation and permanent displacement of the landslide under the action of the earthquake, and lays a foundation for prediction and evaluation of the whole evolution process of landslide disasters.

Inventors

LI DEJIAN
BAI YANG
WANG ZHENG
LIU LONG
XIE YUHAN
SU XUEJING
ZHANG YINGBIN
YU PENGCHENG

Assignees

西南交通大学

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (10)

1. The method for simulating the whole process of the large deformation of the earthquake landslide based on the grid isolation technology is characterized by comprising the following steps of: According to the geometric form data of the side slope, a second-order convection particle domain interpolation object particle method is adopted to establish a background grid, a calculation domain is discretized into a free field column, a main slope body and a safety isolation belt region, differential mechanical parameters are given to each region, and a multi-medium substance point discrete model is constructed; Based on a multi-medium substance point discrete model, carrying out quasi-static calculation by a method combining gravity loading and local damping to obtain a physical static equilibrium state; Acquiring a seismic acceleration time interval record, integrating, correcting a base line and converting stress to construct an equivalent incident shear stress time interval suitable for an elastic absorption boundary; Taking a static equilibrium state as an initial condition, entering an explicit dynamic time step circulation, calculating particle momentum and node force, applying virtual viscous coupling force on two sides of a separation belt to realize flexible connection, applying a viscous energy-absorbing boundary on the bottom of a model, preventing drifting on the boundary of the bottom of the model, and completing seismic dynamic analysis and calculation, wherein an equivalent incident shear stress time course is taken as a dynamic load condition applied on the energy-absorbing boundary of the bottom of the model; Based on the applied boundary conditions, solving a momentum equation of a background grid node to obtain node acceleration, mapping the node movement quantity back to particles, updating the speed and position of the particles, performing strain-driven soft hardening coupling constitutive calculation, calculating plastic strain increment according to the stress state and yield criterion of the particles, updating key parameters representing soil body strength, namely soil layer cohesive force and internal friction angle in real time, simulating the evolution process of landslide from cracking to accumulation, and obtaining a full-period particle position coordinate sequence and a particle state variable sequence; and generating a dynamic video and a whole-process displacement cloud picture containing landslide space-time evolution characteristics based on the obtained full-time particle position coordinate sequence and the particle state variable sequence, and analyzing a shearing band through path and a final stacking form.
2. The method for simulating the whole process of the large deformation of the earthquake landslide based on the grid isolation technology as set forth in claim 1, wherein the background grid is established by adopting a second-order convection particle domain interpolation object particle method according to the geometrical form data of the side slope, the calculation domain is discretized into a free field column, a main slope body and a safety isolation belt region, differential mechanical parameters are given to each region, and a multi-medium substance point discrete model is constructed, and the method specifically comprises the following steps: based on MATLAB software, generating a regular Euler background grid in a calculation domain, and forcedly reserving a space between a free field column grid and a main slope grid by using an abscissa topological constraint condition to form a physical safety isolation belt; Determining the position of a soil-rock interface according to the set thickness of a soil layer and a base stratum, identifying particles with longitudinal coordinates lower than the soil-rock interface by using a space coordinate mask, and defining the particles as a base stratum, and defining the particles on the upper side of the base stratum and on the inner side of a separation zone as a soil layer; according to the regional division, the constitutive model and the mechanical parameters of the differentiation of each region are endowed.
3. The method for simulating the whole process of the large deformation of the earthquake landslide based on the grid isolation technology as recited in claim 2, wherein the method for endowing the regional differentiation with the constitutive model and the mechanical parameters according to regional division comprises the following steps: the high elastic modulus and infinite yield strength exceeding a preset threshold value are endowed to the base stratum and the free field column, and the linear elastic mechanism is executed, so that the linear elastic mechanism is only used as a waveguide medium in seismic dynamic analysis and does not generate plastic yield and damage; The initial cohesive force peak value c peak and the internal friction angle peak value are given to the soil layer peak With a cohesion residual value c res , an internal friction angle residual value res Executing a soft hardening coupling elastoplastic mechanism, and providing physical criteria for simulating the whole process evolution of landslide; The transition boundary is given a higher cohesion value than the interior of the main slope to enhance the numerical stability of the bottom contact.
4. The method for simulating the whole process of the large deformation of the earthquake landslide based on the grid isolation technology as recited in claim 1, wherein the quasi-static calculation is carried out by a method combining gravity loading and local damping based on a multi-medium substance point discrete model, and the method comprises the following steps of: Applying gravitational acceleration to the full-field object points, and simultaneously applying non-viscous local damping force to the background grid nodes at each time step; Continuously executing explicit time integration, monitoring the ratio of the full-field kinetic energy E k and the historical peak kinetic energy E k,peak of the system in real time, reflecting the dissipation degree of the kinetic energy of the system according to the corresponding ratio, and judging that the system reaches a physical static equilibrium state when the ratio meets a preset small-order convergence criterion, namely the ratio is lower than a preset threshold; After the static equilibrium state is judged, resetting the kinematic state of the full-field particles, namely zeroing the velocity and the acceleration, so as to eliminate numerical noise remained by quasi-static calculation, and simultaneously completely keeping the current particle position, deformation gradient and Cauchy stress tensor, wherein corresponding physical quantity forms a real initial ground stress field and is used as an initial state of seismic dynamic analysis.
5. The method for simulating the whole process of large deformation of an earthquake landslide based on a grid isolation technology as set forth in claim 1, wherein the steps of obtaining the seismic acceleration time course record and carrying out integration, baseline correction and stress conversion to construct an equivalent incident shear stress time course applicable to an elastic absorption boundary comprise the following steps: importing a target seismic acceleration time interval record file from an external seismic vibration database, reading the externally input seismic acceleration time interval record file, extracting a time sequence t and a seismic acceleration sequence a (t), and converting the discrete seismic acceleration sequence a (t) into an original velocity time interval v raw (t) by adopting a trapezoid numerical integration method; Performing linear trending term processing and cosine window attenuation on the original speed time course v raw (t) to obtain a corrected speed time course v (t); based on the one-dimensional elastic wave propagation theory and the elastic bottom boundary condition, the corrected velocity time course v (t) is converted into an equivalent incident shear stress time course tau in (t).
6. The method for simulating the whole process of the large deformation of the earthquake landslide based on the grid isolation technology as claimed in claim 1, wherein the static equilibrium state is taken as an initial condition, the method enters an explicit dynamic time step cycle, the particle momentum and the node force are calculated, virtual viscous coupling force is applied to two sides of the isolation belt to realize flexible connection, a viscous energy absorption boundary is applied to the bottom of the model, drifting is prevented at the bottom boundary of the model, and the earthquake dynamic analysis calculation is completed, wherein an equivalent incident shear stress time course is taken as a dynamic load condition applied to the energy absorption boundary of the bottom of the model, and the method specifically comprises the following steps: According to a second-order solving process of the particle interpolation object point method of the particle sub-domain, mapping the mass and momentum carried by particles to background grid nodes, and calculating node momentum and node force; Applying Lysmer-Kuhlemeyer viscous boundary conditions on the bottom of the model based on one-dimensional elastic wave propagation theory and wave field superposition principle, and superposing incident stress F input , wherein A node is the effective stress area represented by the boundary node, Is equivalent incident shear stress time course; The earthquake fluctuation response of the free field column is transmitted to the main slope body through the coupling force F dashpot , and simultaneously reflected scattered waves generated in the main slope body are absorbed, and the main slope body and the free field column are allowed to generate relative sliding when the main slope body is greatly deformed, so that rigid locking of the boundary is prevented; and dynamically identifying the substrate boundary layer particles with the ordinate y smaller than the threshold delta at each time step, and displacing the vertical speed and the vertical direction of the substrate boundary layer particles to 0 to realize anti-drift correction.
7. The method for simulating the whole process of large deformation of the earthquake landslide based on the grid isolation technology as claimed in claim 1, wherein the method is characterized in that based on the applied boundary condition, a momentum equation of a background grid node is solved, the node acceleration is obtained, then the node movement quantity is mapped back to particles, the speed and the position of the particles are updated, the soft hardening coupling constitutive calculation of strain driving is performed, the plastic strain increment is calculated according to the stress state and the yield criterion of the particles, the key parameters representing the soil body strength, namely the clay layer cohesive force and the internal friction angle are updated in real time, the evolution process from the initiation to the accumulation of the landslide is simulated, and the full-period particle position coordinate sequence and the particle state variable sequence are obtained, and the method specifically comprises the following steps: when the stress is updated, calculating the equivalent plastic strain increment of the current time step through a rollback mapping algorithm of the constitutive model And time integrating the strain to obtain the accumulated equivalent plastic strain of the particles: ; Based on cumulative equivalent plastic strain p Defining structural damage state of material, introducing critical plastic strain crit As the softening rate control parameter, a destruction factor S is calculated as follows: In the formula, if S=1.0 represents that the soil structure is perfect, S=0.0 represents that the soil structure is completely destroyed and enters a residual state, p In order to accumulate an equivalent plastic strain, crit A critical plastic strain set according to the brittleness/ductility characteristics of the soil material; The method is used for simulating the intensity attenuation caused by the structural loss of the soil body under the action of strong earthquake, and is used for judging whether the soil body is yielded at the next moment, the current soil layer cohesive force c cur is reduced along with the reduction of a destruction factor S, and the calculation formula from the initial peak value c peak to the residual value c res ,c cur is as follows: wherein c peak is an initial peak value of cohesion, and c res is a set residual value of cohesion; Establishing a soil layer friction recovery mechanism, which comprises the following steps: a. in the initial stage, the peak value of the internal friction angle of the initial soil layer is set peak In the extremely short time of simulated earthquake, the saturated soil body is in a non-drainage shearing state, the initial material parameter non-drainage shearing strength S u is only provided by cohesive force, at the moment, the material shows a non-drainage shearing property, and the envelope surface is destroyed to be degenerated to be Tresca arc yield criterion; b. in the evolution stage, as the sliding body is damaged by large deformation, the water pressure of the super pore is dissipated or particles are rearranged, the friction effect is gradually recovered, and the current internal friction angle is obtained cur Dynamically increasing to a residual value with decreasing S res ; Wherein, the cur The calculation formula is as follows: In the formula, peak As an initial peak value of the internal friction angle, res Is the residual value of the set internal friction angle; the dynamic energy dissipation and accumulation evolution process of the landslide due to the recovery of the friction intensity in a natural state is truly simulated by utilizing the friction resistance generated by the high confining pressure of the deep soil body in the later stage of the landslide movement, so that the final disaster range is accurately predicted.
8. The method for simulating the whole process of large deformation of a seismic landslide based on a grid isolation technology as claimed in claim 7, wherein the method for generating a dynamic video and a whole process displacement cloud picture containing the space-time evolution characteristics of the landslide based on the obtained full-time particle position coordinate sequence and particle state variable sequence comprises the following steps of: reading the full-period particle position coordinate sequence by MATLAB software With a sequence of particle state variables, i.e. cumulative plastic strain ; Drawing the particle position according to frames by taking the time t as an axis to generate a dynamic video reflecting the landslide movement track; extracting final moment accumulated plastic strain And a high value area exceeding a preset threshold value is used for identifying a through path of the shearing sliding belt, and the final disaster influence range is determined according to the front edge coordinates of the accumulation body.
9. The method for simulating the whole process of the large deformation of the earthquake landslide based on the grid isolation technology as recited in claim 2, wherein the method for simulating the whole process of the large deformation of the earthquake landslide based on the grid isolation technology is characterized in that a regular Euler background grid is generated in a calculation domain based on MATLAB software, and a physical safety isolation belt is formed by forcing a space between a free field column grid and a main slope grid by utilizing an abscissa topology constraint condition, and specifically comprises the following steps: setting the horizontal distance between the free field column grid and the main slope grid to meet the following conditions: Wherein W gap is the width of the safety isolation belt, R s is the radius of the supporting domain of the material point shape function, and the interference is interpolated by the physical partition shape function.
10. A method of simulating the full process of seismic landslide large deformation based on grid isolation technology of claim 5 and further comprising: The original velocity schedule v raw (t) is calculated as follows: Wherein t i is the current time, Δt is the sampling time interval, k represents the kth time step from the starting time to the current time, a (t k) is the input seismic acceleration amplitude corresponding to the kth time step, a (t k-1 ) is the input seismic acceleration amplitude corresponding to the kth-1 time step, namely the last time; The calculation formula of the corrected velocity schedule v (t) is as follows: Wherein A, B is a linear trend coefficient obtained by least square fitting, wherein A is a slope of a linear trend, and represents a linear drift rate of a speed caused by a constant acceleration error in a speed baseline correction process, B is an intercept of the linear trend, and represents an initial speed shift constant at an integration starting time, v detrend (T) is an intermediate speed time course after linear trend removal processing, w (T) is a cosine decay window function, and is defined as when T > T start is a transition period at the tail of the time course The rest period w (T) =1.0, wherein T start is the starting time of the cosine decay window, and T end is the ending time of the seismic wave recording; the equivalent incident shear stress time interval τ in (t) is calculated as follows: Wherein ρ base is the matrix density, C s,base is the shear wave velocity of the matrix, and coefficient 2 is the wave field superposition coefficient of the elastic bottom boundary for counteracting the attenuation effect of the absorption boundary on the incident wave.

Description

Seismic landslide large deformation overall process simulation method based on grid isolation technology Technical Field The invention relates to the technical field of geotechnical engineering, in particular to a method for simulating the whole process of large deformation of an earthquake landslide based on a grid isolation technology. Background The existing grid method (finite element) is often limited by the convergence problem caused by grid distortion when the problem of large deformation of the earthquake landslide is solved. Although the object point method (Material Point Method, MPM) effectively expands the calculation capability of large deformation, the method still has challenges in the refinement of dynamic boundaries, namely, a conventional boundary processing mode is easy to introduce non-physical reflection interference between a main model and a free field, and the complexity of data interaction and time-step coordination is increased by adopting a separate calculation strategy. In addition, the conventional single-softening constitutive model has limitation in reproducing the complete evolution of landslide from cracking to friction accumulation, is easy to show continuous sliding characteristics which are not in accordance with reality, and is also easy to influence by substrate speed drift in the process of power integral calculation during long-term holding. Therefore, the integrated simulation method capable of considering accurate input of the dynamic boundary, inhibiting numerical drift and truly reflecting the whole landslide mechanical behavior has theoretical and practical significance. Disclosure of Invention The invention provides a method for simulating the whole process of large deformation of an earthquake landslide based on a grid isolation technology, which aims to solve the technical problems that when the method is used for processing the earthquake landslide, the reflection interference of boundary waves of a free field is serious, the numerical drift of power integration is remarkable when the free field is long, and the whole process of the landslide from brittleness to large deformation friction accumulation is difficult to continuously and accurately simulate under the same computing frame. According to a first aspect, in one embodiment, there is provided a method for simulating a large deformation whole process of a seismic landslide based on a grid isolation technology, the method comprising: According to the geometric form data of the side slope, a second-order convection particle domain interpolation object particle method is adopted to establish a background grid, a calculation domain is discretized into a free field column, a main slope body and a safety isolation belt region, differential mechanical parameters are given to each region, and a multi-medium substance point discrete model is constructed; Based on a multi-medium substance point discrete model, carrying out quasi-static calculation by a method combining gravity loading and local damping to obtain a physical static equilibrium state; Acquiring a seismic acceleration time interval record, integrating, correcting a base line and converting stress to construct an equivalent incident shear stress time interval suitable for an elastic absorption boundary; Taking a static equilibrium state as an initial condition, entering an explicit dynamic time step circulation, calculating particle momentum and node force, applying virtual viscous coupling force on two sides of a separation belt to realize flexible connection, applying a viscous energy-absorbing boundary on the bottom of a model, preventing drifting on the boundary of the bottom of the model, and completing seismic dynamic analysis and calculation, wherein an equivalent incident shear stress time course is taken as a dynamic load condition applied on the energy-absorbing boundary of the bottom of the model; Based on the applied boundary conditions, solving a momentum equation of a background grid node to obtain node acceleration, mapping the node movement quantity back to particles, updating the speed and position of the particles, performing strain-driven soft hardening coupling constitutive calculation, calculating plastic strain increment according to the stress state and yield criterion of the particles, updating key parameters representing soil body strength, namely soil layer cohesive force and internal friction angle in real time, simulating the evolution process of landslide from cracking to accumulation, and obtaining a full-period particle position coordinate sequence and a particle state variable sequence; and generating a dynamic video and a whole-process displacement cloud picture containing landslide space-time evolution characteristics based on the obtained full-time particle position coordinate sequence and the particle state variable sequence, and analyzing a shearing band through path and a final stacking form. Further, according to