CN-121980990-A - Landslide body water-entering surging overall process simulation method

CN121980990ACN 121980990 ACN121980990 ACN 121980990ACN-121980990-A

Abstract

The application relates to a landslide body water-entering surge whole process simulation method which comprises the following steps of establishing a geometric modeling and calculating domain, establishing a geometric model of the calculating domain in three-dimensional modeling software based on actual topographic data, dividing and locally encrypting grids of the calculating domain, setting physical models and material parameters, setting a discrete meta model in the EDEM, establishing a particle model of the landslide body, setting a fluid dynamic model in Fluent, setting EDEM-Fluent coupling, establishing bidirectional coupling through a coupling interface of the EDEM and Fluent, setting initial conditions and boundary conditions in the Fluent and the EDEM respectively, starting an EDEM and Fluent solver simultaneously for transient coupling calculation, and carrying out post-processing and result analysis, wherein the whole surge disaster chain process is estimated through analysis carried out in the EDEM and Fluent post-processing respectively.

Inventors

CHEN SHIZHUANG
LIANG HUI
CHU WEIJIANG
ZHENG PENGXIANG
LEI JIE
LIU NING

Assignees

中国电建集团华东勘测设计研究院有限公司

Dates

Publication Date: 20260505
Application Date: 20251226

Claims (10)

1. The full-process simulation method for the water-entering surge of the landslide body is characterized by comprising the following steps of: s1, establishing a geometric modeling and calculation domain, namely establishing a geometric model of the calculation domain in three-dimensional modeling software based on actual topographic data, and carrying out region identification and division on the geometric model; S2, calculating domain grid division and local encryption; s3, setting physical models and material parameters, namely setting a discrete element model in the EDEM, and building a particle model of a landslide body according to the physical and mechanical properties of a rock-soil body; s4, setting EDEM-Fluent coupling, namely establishing bidirectional coupling through a DPM coupling interface of the EDEM and the Fluent; S5, setting initial conditions and boundary conditions, namely respectively presetting the initial conditions and the boundary conditions in Fluent and EDEM; S6, solving, calculating and monitoring, namely starting an EDEM and a Fluent solver at the same time, and performing transient coupling calculation; S7, post-processing and result analysis, namely analyzing the motion track, speed change and crushing condition of the landslide body in the EDEM post-processing, analyzing the waveform, wave height, propagation speed and flow field information of the surge in the Fluent post-processing, and comprehensively evaluating the whole process of the surge disaster chain.
2. The method for simulating the whole water-entering and surging process of a landslide body according to claim 1, wherein in the step S1, the divided geometric model comprises a landslide body source region, a water body region, an air region, a river bed region and a reservoir bottom region; the step S2 specifically comprises the steps of adopting a polyhedral grid or a hexahedral core grid to calculate a grid by adopting CFD (computational fluid dynamics) with high quality in the water body area and the air area, carrying out local grid encryption on a landslide body motion path and a water inlet area of a landslide body source area so as to capture complex fluid-solid interfaces and surge details, setting a dynamic grid updating area, and reserving a grid reconstruction space for free liquid level large deformation caused by subsequent landslide body impact.
3. The method for simulating the whole water-entering surge process of a landslide body according to claim 2, wherein the step S3 further comprises the steps of: Setting the density, poisson's ratio, shear modulus, coefficient of restitution and static/dynamic friction coefficient of particles, defining the geometrical shapes of a bank slope substrate and a river bed as boundary conditions, and setting the contact attribute of the bank slope substrate and the river bed; In Fluent, the VOF multiphase flow model is used to capture the dynamic change of the free water-gas liquid level, activate the k-omega SST turbulence model to simulate the turbulence effect in the process of surging, set the density and viscosity of water and air, and set the gravitational acceleration.
4. The landslide body water-entering surge whole process simulation method according to any one of claims 1-3 is characterized in that in the step S4, a data exchange mechanism is built, a coupling time step is optimized and an acting force model is customized when the bidirectional coupling is built, wherein the data exchange mechanism comprises that the EDEM transmits position, speed and volume information of each particle to Fluent in real time, the Fluent transmits calculated fluid speed, pressure and density information of a grid unit where each particle is located, and the calculated drag force, pressure gradient force and virtual mass force acting on the particle are fed back to the EDEM; setting the calculated time step of the EDEM as N times of the Fluent time step, wherein N is an integer, determining an optimal N value through trial calculation to ensure that the EDEM meets the requirement of the Rayleigh wave time step and is coordinated with the Fluent time step; The acting force model customization comprises the steps of adopting Gidaspow model to explicitly calculate buoyancy force and pressure gradient force aiming at particles immersed in water, and accurately reflecting the action of fluid on the particles.
5. The landslide mass water-entering surge whole-process simulation method according to claim 4, wherein the time step of EDEM Based on Rayleigh wave time step criteria: ; In the formula, At the level of the minimum particle radius, In order to achieve a particle density of the particles, In order to achieve a shear modulus, the polymer is, Is the poisson's ratio, and at the same time, Fluid time step with Fluent The relation needs to be satisfied: , is an integer with a value range of 5-20.
6. The method for simulating the whole water-entering and surging process of a landslide body according to claim 4, wherein in the step S5, the preset initial conditions comprise setting a static water pressure field in Fluent, defining an initial water line, generating a particle group representing the landslide body at a source region position of a bank slope in EDEM, and giving an initial stress state; The preset boundary conditions comprise that the top of the calculation domain is an atmospheric pressure boundary, the bottom of the calculation domain is a slip-free boundary, the far-field boundary is a fixed water head pressure boundary, and the bank slope base and the river bed are arranged to be fixed geometric wall surfaces.
7. The method for simulating the whole water-entering surge of a landslide body according to claim 4, wherein the step S6 further comprises the following steps: The dynamic grid of Fluent is reconstructed in real time to change grid caused by particle motion and large deformation free liquid level.
8. A landslide body water-entering surge whole process simulation method according to any one of claims 1-3 or 5-7, wherein when a discrete meta-model is set in EDEM, the method comprises the following steps: The motion of each particle is calculated in EDEM by solving newton's second law, the control equation of which is as follows: Translational movement: ; rotational movement: ; In the formula, And The mass and moment of inertia of the particles, respectively; And The translational and rotational speeds of the particles, respectively; Is the resultant of the contact forces between the particles; Acting force of fluid on particles; is a gravity acceleration vector; the resultant moment generated for the contact force; Wherein the contact force Consisting of normal and tangential components, the Hertz-Mindlin contact model can be used: normal force: ; Tangential force: ; In the formula, For an equivalent young's modulus, For an equivalent shear modulus, the shear modulus, In order to be of an equivalent radius, And The amount of normal and tangential overlap respectively, Is the coefficient of friction.
9. The landslide body water-entering surge whole process simulation method according to any one of claims 1-3 or 5-7, wherein when the hydrodynamic model is set in Fluent, the method comprises the following steps: fluent solves the Navier-Stokes based equation, whose control equation is as follows: Continuity equation: ; momentum conservation equation: ; In the formula, Is the fluid density; Is a fluid velocity vector; Is static pressure; is a stress tensor, related to viscosity; Is a momentum source term representing the reaction force of particles relative to the fluid; in Fluent, the VOF multiphase flow model is modeled by introducing a volume fraction To track the interface(s), Represents water or air, and the control equation is as follows: ; Needs to meet the requirements of 。
10. The method for simulating the whole water-entering surge of a landslide body according to any one of claims 1 to 3 or 5 to 7, wherein the coupling is performed at each Fluent time step when the EDEM-Fluent coupling is set In-process, EDEM provides particle information, fluent calculates fluid force and returns to EDEM, interaction force of particles and fluid The calculation formula is as follows: ; In the formula, For drag force, which is the resistance generated by the relative motion of fluid and particles, the calculation formula is: ; the drag coefficient is related to the reynolds number of the particle and the volume fraction of the fluid where the particle is located; Is the fluid density; Is the projection area of the particles; Fluid velocity for the grid where the particle center is located; Is the particle velocity; For the pressure gradient force, the calculation formula is: ; In the form of a volume of the particles, A pressure gradient at the location of the particle; the virtual mass force is the force required for accelerating the fluid around the particles, and the calculation formula is as follows: Taking 0.5 for spherical particles as a virtual quality coefficient; Is a derivative of the fluid substance; for buoyancy, generated by hydrostatic pressure, the formula is: 。

Description

Landslide body water-entering surging overall process simulation method Technical Field The application relates to the technical field of geological disaster simulation, in particular to a landslide body water-entering surge whole-process simulation method. Background After the reservoir stores water, the water level in the reservoir area is rapidly raised, so that the bank slope which is originally in a dry state is gradually immersed by the reservoir water, and the underground water level is also raised. Under the common influence of factors such as reservoir water level fluctuation, rainfall, earthquake and the like, reservoir bank side slopes are easy to be unstable, and landslide disasters are induced. The landslide in the reservoir area is different from the common landslide, and the sliding body of the landslide possibly causes two kinds of chain disasters after entering the water body, namely, the river channel is blocked to form a barrier lake, and the surge is generated and propagates upwards and downwards along the river channel, so that serious threat is formed to coastal facilities and life and property safety of people. Especially in mountain reservoirs, the river channel is narrow, the surge energy is not easy to dissipate, the surge wave with huge energy can propagate for tens of kilometers, and the influence range is wide. Therefore, accurate simulation and prediction of landslide surge become the key for disaster prevention and reduction. The current research method mainly comprises three types of physical model test, empirical formula method and numerical simulation, and the numerical simulation method is most widely applied. However, the numerical simulation method still has certain limitations that the pure fluid dynamics method often simplifies the sliding body into a rigid body or a moving boundary with a preset shape, the internal fragmentation of the sliding body, the interaction of particles and the complex coupling process of the particles and fluid after entering water are difficult to simulate, the initial surge excitation mechanism is distorted, the pure discrete element method can accurately describe the movement and fragmentation of the sliding body, but has insufficient simulation capability on the actions of fluid power, buoyancy and the like, the surge propagation process is difficult to accurately describe, the simple unidirectional coupling method only considers the impact of the sliding body on the fluid, ignores the influence of the fluid reaction on the movement of the sliding body, and has incomplete coupling effect and limited precision. Disclosure of Invention The application provides a landslide body water-entering surge whole process simulation method, which can more accurately and efficiently simulate the whole process from solid landslide movement to fluid surge propagation of a disaster chain, and provides theoretical support and technical support for accurate prediction of landslide surge height. The application provides a landslide body water-entering surge whole process simulation method which comprises the following steps: s1, establishing a geometric modeling and calculation domain, namely establishing a geometric model of the calculation domain in three-dimensional modeling software based on actual topographic data, and carrying out region identification and division on the geometric model; S2, calculating domain grid division and local encryption; s3, setting physical models and material parameters, namely setting a discrete element model in the EDEM, and building a particle model of a landslide body according to the physical and mechanical properties of a rock-soil body; s4, setting EDEM-Fluent coupling, namely establishing bidirectional coupling through a DPM coupling interface of the EDEM and the Fluent; S5, setting initial conditions and boundary conditions, namely respectively presetting the initial conditions and the boundary conditions in Fluent and EDEM; S6, solving, calculating and monitoring, namely starting an EDEM and a Fluent solver at the same time, and performing transient coupling calculation; S7, post-processing and result analysis, namely analyzing the motion track, speed change and crushing condition of the landslide body in the EDEM post-processing, analyzing the waveform, wave height, propagation speed and flow field information of the surge in the Fluent post-processing, and comprehensively evaluating the whole process of the surge disaster chain. In an alternative scheme, in the step S1, the divided geometric model includes a landslide body source region, a water body region, an air region, a river bed region and a reservoir bottom region; the step S2 specifically comprises the steps of adopting a polyhedral grid or a hexahedral core grid to calculate a grid by adopting CFD (computational fluid dynamics) with high quality in the water body area and the air area, carrying out local grid encryption on a landslide body motion path an