A fluid-solid coupling rock-soil disaster simulation method based on CZM and CEL
By using CZM and CEL-based methods, simplifying the model and combining specific elements and laws, the computational complexity and error problems in existing technologies are solved, and accurate simulation of landslide-induced surge waves is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- POWER CHINA KUNMING ENG CORP LTD
- Filing Date
- 2023-09-05
- Publication Date
- 2026-07-24
Smart Images
Figure CN117350095B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of landslide-induced surge simulation methods, specifically involving a fluid-structure interaction geotechnical disaster simulation method based on CZM and CEL. Background Technology
[0002] Landslide-induced surges typically release enormous amounts of energy, threatening lives, damaging infrastructure, causing environmental pollution, and resulting in significant economic losses. Therefore, accurately predicting the hazards of landslide-induced surges using numerical models is crucial for future research and disaster prevention.
[0003] Existing numerical simulation methods have certain limitations in handling large deformation problems and fluid-structure interaction problems. For example, the DEM-CFD coupled method has high computational complexity, especially when dealing with large-scale and long-term simulations, requiring a lot of computational resources and time for particle-fluid coupling calculations. Another example is the SPH method, which introduces numerical diffusion, which will affect important details, as shown in application publication number CN115795985A. Yet another example is the MPM material point method, which suffers from element crossover error and null space error because the number of integration points (material points) in the element is not constant. Summary of the Invention
[0004] This invention proposes a fluid-structure interaction simulation method for soil and rock disasters based on CZM and CEL, which avoids the above-mentioned shortcomings and can solve the problem of the impact of fracture behavior inside the landslide body on the surge height, and explore the hazards of soil and rock disasters.
[0005] To achieve the above objectives, this invention provides a fluid-structure interaction simulation method for soil and rock disasters based on CZM and CEL, comprising the following steps: S1: Simplifying the physical model by reducing the complex three-dimensional geological model to a two-dimensional physical geometric model; S2: Dividing different regions in the physical geometric model using different meshes; S3: Setting boundary conditions by assuming the base and soil have continuous homogeneity in the initial state, with no initial stress, and considering the gravitational acceleration of the landslide body; the displacement of the entire physical geometric model is fixed, and the degrees of freedom of all nodes on the sliding surface are fixed; all degrees of freedom of nodes on the base are fixed; S4: Modeling the contact surface between the landslide body and the soil, as well as the relationships between landslide body elements, using the CZM method; that is, ensuring the contact surface between the landslide body and the soil, as well as the relationships between landslide body elements, follows the traction separation law, and setting the friction coefficient of the contact surface between the landslide body and the soil to 0.16; analyzing the fluid-structure interaction behavior of the landslide body after contact with water using the CEL method; S5: Simulating and obtaining the surge height.
[0006] Further, in step S2, in the Abaqus software, the base region is represented by quadrilateral solid elements; the landslide body, water, and void region are represented by CEL elements; and the contact surface between the landslide body and soil, as well as between landslide body elements, are represented by Cohesive elements. Soil cohesion is characterized using cohesive elements, with the tensile strength of the cohesive elements set as the soil cohesion.
[0007] Furthermore, in step S4, the traction separation law adopts a linear softening law, as shown in equation (1): in, t n The normal traction cohesion of the model is represented by , and D represents the damage factor that occurs after the model reaches its strength limit. This represents the model cohesion when no damage has occurred.
[0008] Furthermore, in step S4, the Euler volume fraction EVF is used to track the flow of material through the mesh. The Euler volume fraction EVF can be exported by the post-processing module of Abaqus. The EVF of water is set to 1, indicating complete occupancy, while the EVF of the void region is set to 0, indicating that there is no material at all. During the process of the landslide entering the water, the water elements will flow into the void region, causing the EVF value of the void region to change.
[0009] Furthermore, in the Abaqus software, the properties of the Cohesive cell are set as follows: Table 1 Properties of Cohesive Units ;
[0010] Beneficial effects:
[0011] 1. The CEL method was used to analyze the fluid-structure interaction behavior of the landslide body after contact with water, and the CZM method was used to analyze the fracture behavior between the landslide body and the soil, as well as within the landslide body. Both methods comprehensively elucidate the entire process of landslide-induced surge, thus avoiding the shortcomings of existing methods.
[0012] 2. The properties and linear softening law of the Cohesive element were set to make the fracture behavior between the landslide body and the soil and inside the landslide body more accurate. Attached Figure Description
[0013] Figure 1 This is a flowchart illustrating the landslide-induced surge simulation method based on CZM-CEL coupling; Figure 2 The geological model is simplified into a two-dimensional geometric model diagram; Figure 3This is a schematic diagram showing the grid division of each region; Figure 4 This involves comparing the experimental results of landslide movement and wave generation at different times with the simulation results of this scheme; Figure 4 (a) is a diagram showing the test results after the landslide body came into contact with water; Figure 4 (b) is a simulation diagram of the landslide after it comes into contact with water; Figure 4 (c) is a diagram showing the experimental results of the landslide body and water when the cavity began to form; Figure 4 (d) is a simulation diagram of the landslide body and water when the cavity begins to form; Figure 4 (e) is a diagram showing the test results of the landslide body and water during the cavity collapse; Figure 4 (f) is a simulation diagram of the landslide body and water during the cavity collapse; Figure 4 (g) is a diagram showing the test results of the landslide body and water after the cavity completely collapsed; Figure 4 (h) is a simulation diagram of the landslide body and water after the cavity has completely collapsed; Figure 5 It is a comparison graph of the surge height in the test results and the surge height in the simulation results over time throughout the entire process. Detailed Implementation
[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0015] See Figure 1 A fluid-structure interaction geotechnical disaster simulation method based on CZM and CEL includes the following steps: S1: Simplify the physical model, reducing the complex three-dimensional geological model to a two-dimensional physical geometric model.
[0016] Since the Euler method is only applicable to three-dimensional elements, in order to reduce the degrees of freedom and computation time, a pseudo-two-dimensional (2D) model with only one element was established in the z-direction of the model (see...). Figure 2 ).
[0017] See Figure 2 In this embodiment, the slope angle and headland angle of the model are both set to 45°, and the still water height is set to 112 meters. The highest point of the landslide is 915 meters above the water level, the lowest point is 230 meters above the water level, and the center of mass of the landslide is located above the water level of 610 meters.
[0018] See Figure 3 S2: Grid division, which involves dividing different types of grids for different regions.
[0019] Specifically, in Abaqus software, the base region is represented by quadrilateral solid elements; The landslide body, water, and void zone are represented using CEL units; Cohesive elements are used at the contact surfaces between the landslide body and the soil, as well as between landslide body elements. Soil cohesion is characterized using cohesive elements, as shown in Table 1, where the tensile strength of the cohesive element is set to the soil cohesion.
[0020] The properties of the cohesive element are shown in Table 1: Table 1 Properties of Cohesive Units ;
[0021] S3: Boundary Condition Treatment: The base and soil are assumed to be continuous and homogeneous in the initial state, with no initial stress, and the gravitational acceleration of the landslide is considered. The entire model is perpendicular to... Figure 2 The displacement in the plane of the paper is fixed, and the degrees of freedom of all nodes on the sliding surface (the contact surface on the landslide body) are fixed. The degrees of freedom of all nodes on the base are fixed.
[0022] S4: The contact surface between the landslide body and the soil, as well as the relationships between landslide body elements, are modeled using the CZM method. During material fracture, stress transfer follows the traction separation law. The friction coefficient of the contact surface between the landslide body and the soil is set to 0.16. In this embodiment, the linear softening law is adopted, that is, when the stress reaches the strength limit, linear softening will occur. As shown in equation (1), where, t n The normal traction cohesion of the model is represented by , and D represents the damage factor that occurs after the model reaches its strength limit. This represents the model cohesion when no damage has occurred. The following softening constitutive relation is the constitutive relation of the cohesive element in step S2.
[0023] The landslide mass and water were represented using CEL elements. In numerical methods employing CEL, the flow of material through the mesh was tracked by calculating the Euler volume fraction (EVF). The Euler volume fraction (EVF) can be exported as a numerical value using Abaqus' post-processing module.
[0024] EVF, as a quantifiable metric, represents the relative occupancy of material considered in each Euler element. An EVF value of 1 indicates complete saturation of material within the Euler element, while an EVF value of 0 indicates complete absence of material. Water has an EVF of 1, representing complete occupancy, while the EVF of the void region is set to 0, representing the complete absence of material. During the process of water entering the landslide mass, water elements flow into the void region, causing changes in the EVF value of the void region.
[0025] The CEL method is used to analyze the fluid-structure interaction behavior of a landslide after it comes into contact with water, while the CZM method is used to analyze the fracture behavior of the landslide and the soil, as well as the landslide itself. Both methods fully elucidate the entire process of a landslide initiating a surge.
[0026] S5: Extract the simulation results from Abaqus, such as Figure 4 As shown in (b), (d), (f), and (h), the model is compared with experimental data to verify its rationality. Figure 5 As shown.
[0027] When a landslide impacts water, the formation of cavities can be observed. Figure 4 (b), (d), (f)), and finally the water flow re-attached to the back of the landslide body, causing the cavity to collapse. Figure 4 (h)). During the sliding process at the base of the landslide, due to the interaction between water and the landslide mass, the landslide mass first accumulates, and then its thickness gradually decreases. The leading edge of the landslide ( Figure 4 (b), (d), (f), and (h) are all on the right side and are nearly vertical throughout the sliding process, which is consistent with the experimental results.
[0028] Figure 5 The surge records at x = 885 meters were compared (red represents the simulation results, black represents the experimental results). In the numerical simulation, the maximum water level elevation at the x = 885 m section reached 153 m, similar to the field data at 150 m and the experimental results at 152 m. Furthermore, the wave trend throughout the entire process at this section matched the experimental results well. The lag at the peak of the curve in the numerical simulation may be due to the method not modeling the landslide as a particle flow; the friction in the simulation is sliding friction, not the rolling friction during landslide movement. Figure 5 The results show that this method is applicable to the simulation of landslide-induced waves, i.e., the simulation of soil and rock disaster results.
[0029] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.
Claims
1. A fluid-structure interaction method for catastrophic simulation of soil and rock disasters based on CZM and CEL, characterized in that, Includes the following steps, S1: Simplify the physical model, reducing the complex three-dimensional geological model to a two-dimensional physical geometric model; S2: Divide different regions in the physical geometry model using different grids; S3: Set boundary conditions, assuming that the base and soil are continuous and homogeneous in the initial state, with no initial stress, and consider the gravitational acceleration of the landslide body; the displacement of the entire physical geometric model is fixed, the degrees of freedom of all nodes on the sliding surface are fixed, and the degrees of freedom of all nodes on the base are fixed. S4: The CZM method is used to model the contact surface between the landslide body and the soil, as well as the relationships between landslide body elements; that is, the traction separation law is followed between the contact surface between the landslide body and the soil, and between the landslide body elements, and the friction coefficient of the contact surface between the landslide body and the soil is set to 0.16; the fluid-structure interaction behavior of the landslide body after contact with water is analyzed using the CEL method. In step S4, the traction separation law adopts the linear softening law, as shown in equation (1): ； in, This represents the normal traction cohesion of the model. This represents the damage factor that occurs after the model reaches its strength limit. This represents the model's cohesion when no damage has occurred; In step S4, the Euler volume fraction EVF is used to track the flow of material through the mesh. The Euler volume fraction EVF is exported with specific values through the Abaqus post-processing module. The EVF of water is set to 1, indicating complete occupancy, while the EVF of the void region is set to 0, indicating that there is no material at all. During the process of the landslide entering the water, the water elements will flow into the void region, causing the EVF value of the void region to change. S5: Simulate and obtain the surge height.
2. The fluid-structure interaction geotechnical disaster simulation method based on CZM and CEL according to claim 1, characterized in that, In step S2, in the Abaqus software, the base area is represented by quadrilateral solid elements; the landslide body, water, and void area are represented by CEL elements; the contact surface between the landslide body and the soil, as well as the landslide body elements, are represented by Cohesive elements. The soil cohesion is characterized by Cohesive elements, and the tensile strength of the Cohesive elements is set to the soil cohesion.
3. The fluid-structure interaction geotechnical disaster simulation method based on CZM and CEL according to claim 1, characterized in that, In Abaqus software, the properties of a Cohesive cell are set as follows: 。