SPH-based debris flow water tank experiment simulation method

Abstract

The invention specifically discloses an SPH-based debris flow water tank experiment simulation method, and relates to the technical field of geological disaster simulation and fluid dynamics. The method comprises the following steps: S1, inputting water tank size parameters according to experimental requirements and generating a water tank model terrain; s2, debris flow rheological parameters are input, and solid-liquid two-phase SPH particles are generated; s3, applying wall surface repulsive force according to the geometrical morphology of the water tank and the accumulation area so as to set normal boundary conditions, defining an initial velocity field and hydrostatic pressure distribution, adopting an improved solid-phase fractional coupling friction-turbulence model and an SPH method for coupling solution, and calculating debris flow flowing and interaction; and S4, outputting a simulation result. According to the method, the problems of high cost, complex operation, long period and potential safety hazards of a traditional physical experiment are solved, the rheological characteristics and the movement law of the debris flow are accurately described, a high-precision numerical simulation means is provided for the experiment, and disaster mechanism research and disaster prevention and reduction measure formulation are assisted.

Description

Technical Field

[0001] This invention relates to the field of geological disaster simulation and fluid dynamics technology, and in particular to an experimental simulation method for debris flow flume based on SPH. Background Technology

[0002] Debris flows are a frequent and highly hazardous geological hazard, and research on their movement characteristics and deposition patterns is of crucial guiding significance for disaster prevention and mitigation. Indoor flume experiments are currently the core method for exploring the hydrodynamic characteristics and disaster evolution mechanisms of debris flows. By constructing a scaled-down flume model, the flow path, velocity changes, and deposition morphology of debris flows can be observed directly, providing basic data support for disaster mechanism analysis.

[0003] However, traditional debris flow flume physics experiments have significant limitations in practical applications, severely restricting research efficiency and depth: 1. High experimental costs: It requires the construction of a high-precision physical water tank device, and the consumption of supporting materials (such as simulated sediment and water bodies) is large. The economic investment in a single experiment from device construction, material preparation to equipment maintenance is high, and it is difficult to support batch experiments with multiple variables and multiple working conditions.

[0004] 2. Complex operation process: The experiment requires precise control of parameters such as the inclination angle of the water tank, the initial mix ratio of the debris flow, and the flow rate supply, which places strict requirements on the professional skills of the experimenters; the parameter adjustment and device debugging process is cumbersome and the accuracy and repeatability of the experimental data are easily affected by operational errors.

[0005] 3. The experiment cycle is long: A single experiment often takes several days to several weeks to complete, from the preparation stage (equipment calibration, material mixing), the operation stage (debris flow and data acquisition) to the closing stage (equipment cleaning, preliminary data processing). If it is necessary to verify the influence of different parameters on the experimental results, the experiment needs to be repeated, which further extends the research cycle.

[0006] 4. Significant safety hazards: During the experiment, the debris flow simulation material (high-concentration mud and sand mixture) has a strong impact force, which may cause damage to the tank wall and splashing of materials, posing a potential threat to the personal safety of the experimenters and the surrounding equipment. The safety risks are significantly increased, especially when simulating high-velocity and high-concentration debris flow scenarios.

[0007] The aforementioned limitations directly restrict the number of physical experiments that can be conducted, making it difficult to systematically investigate the influence of key parameters such as inclination angle, solid volume fraction, and turbulence coefficient on debris flow motion patterns, and hindering a comprehensive understanding of the intrinsic mechanisms of disaster evolution. Furthermore, the complex operating procedures and lengthy experimental cycles increase the difficulty for junior researchers to master experimental principles and become familiar with operational procedures, thus hindering the promotion of related technologies and the training of personnel. Summary of the Invention

[0008] The purpose of this invention is to propose a debris flow flume experimental simulation method based on SPH, which solves the problems of high cost, complex operation, long cycle and safety hazards in existing physical experiments of debris flow flumes, and the resulting constraints on the clarity of disaster mechanisms. It accurately characterizes the rheological properties and motion laws of debris flows, provides a high-precision numerical simulation means for debris flow flume experiments, and lays the foundation for in-depth research on debris flow disaster mechanisms and the formulation of scientific and effective disaster prevention and mitigation measures.

[0009] To achieve the above objectives, this invention proposes an experimental simulation method for debris flow flume based on SPH, the specific steps of which are as follows: Step S1: According to the experimental requirements, input the size parameters of the water tank to construct the water tank model, define the accumulation area and divide the entire water tank model into a grid to generate the water tank model terrain. Step S2: Input debris flow rheological parameters, define solid-liquid two-phase mixing density, and uniformly distribute solid particles and liquid particles according to solid volume fraction and material pool parameters to generate smooth particle hydrodynamic SPH particles of solid and liquid two phases. Step S3: Based on the geometry of the water tank and the accumulation zone, apply repulsive force to the wall of the water tank to set normal boundary conditions. Define the initial velocity field and hydrostatic pressure distribution as initial conditions. Use the improved solid fractional coupled friction-turbulence model and the SPH method to perform coupled solution to calculate the flow and interaction of debris flow. Step S4: Output simulation results, including the coverage area of ​​the debris flow deposition zone, model node and SPH particle velocity change curves, the final deposition profile of the debris flow along the central axis of the flume model, the three-dimensional morphology of the deposition zone, the impact force curves of specific nodes throughout the process, and the maximum impact force distribution throughout the process.

[0010] Preferably, in step S1, the dimensional parameters of the water tank include the length of a single segment. ,width Material pool length Initial depth of debris flow in the material pool , number of segments Inclined angle sequence Dimensions of the stacking area ( ) and grid spacing ;in, The length of the accumulation zone, The width of the accumulation zone.

[0011] Preferably, the water tank model terrain is generated, and the specific steps are as follows: Step S11: Define an orthogonal coordinate system with the midpoint O of the bottom edge of the first water tank as the origin; where, Positive direction is along the width of the water tank. A direction perpendicular to the wide side pointing towards the accumulation area is considered positive. The axis is considered positive when it is vertically upward. Step S12: Model the bottom surface of the single-section water tank and the bottom surface of the material pool; Step S13: Adjust the inclination angle of the water tank sections using a rotation matrix and connect each water tank section to the material pool; Step S14: Define the accumulation area and mesh the entire water tank model.

[0012] Preferably, in step S12, the first i The bottom of each water tank segment is rectangular. A local coordinate system is constructed with the midpoint of the bottom edge of each water tank segment as the origin. The coordinates of the four corner points in the local coordinate system are as follows: ; in, , , , The first i The coordinates of the four corner points of the bottom surface of the water tank in the local coordinate system; No. i The coordinates of the four points in the material pool section in the local coordinate system are as follows: ; in, , , , The first i The coordinates of the four points in the material pool section in the local coordinate system.

[0013] Preferably, in step S13, the first i The segment wraps around the midpoint of its base. of Axis rotation tilt angle The rotation matrix is: ; After rotation, the coordinates of the corner point are updated as follows: ; The first i Midpoint of the end of the segment As the first i +1 segment origin Connect the various sections of the water tank; [The text abruptly ends here, likely due to an incomplete sentence or a formatting error.] n The midpoint of the end of the segment flume As the origin of the material pool The angle remains consistent with the previous section of the water tank, utilizing a rotation matrix. Connect the material pool to the final water tank; where, For the first i The rotation matrix of the segment. For the first n The rotation matrix of the segment.

[0014] Preferably, in step S14, the accumulation region is located in Positive direction, vertex set D Defined as: ; in, x The x-coordinate of the accumulation zone y The vertical coordinate of the accumulation zone; Arrange the entire water tank according to the spacing Discretized into grid points, with an adaptive mesh used at the junctions of multiple tilt angles. Perform grid division; where, k To adjust the coefficient, For the first i The grid spacing of the segment, For the first i The rotation angle of the segment.

[0015] Preferably, in step S2, the rheological parameters of the debris flow include the liquid phase density. turbulence coefficient Solid density and solid volume fraction The steps of SPH particle generation in solid-liquid two-phase smooth particle hydrodynamics are as follows: Step S21: Define the mixing density formula, as follows: ; Step S22: Based on the solid volume fraction Based on the material pool parameter data, solid and liquid phase particles are evenly distributed.

[0016] Preferably, in step S3, the specific steps are as follows: Step S31: Clean the walls of the water tank. Applying a repulsive force, the formula is as follows: ; in, For target fluid particles The total repulsive force from the wall, For boundary particles, For the set of boundary particles, For fluid particles Pressure For the pressure of boundary particle b, For fluid particles density, Let b be the density of the boundary particle. For kernel function, Let be the wall normal vector. Let be the volume of the boundary particle b; Step S32: Define initial conditions, initial velocity field hydrostatic pressure distribution ;in, r For position vectors, denoted as , For mixed density, It is the acceleration due to gravity. The vertical coordinates of the accumulation zone; Step S33: The improved solid-phase fractional coupled friction-turbulence model is coupled with the SPH method to calculate the motion process of debris flow; the formula for calculating the total base shear stress of the improved solid-phase fractional coupled friction-turbulence model is as follows: ; ; ; in, For normal stress, For the magnitude of the flow velocity, Solid volume fraction The relevant dynamic friction coefficient, The coefficient of friction of the substrate. To adjust the parameters, Solid volume fraction The relevant dynamic turbulence coefficients, To adjust the parameters.

[0017] Preferably, in step S4, the coverage area of ​​the debris flow deposition zone... The calculation formula is as follows: ; Project the particle onto the xy plane and calculate the projected area: ; in, For target fluid particles a x-coordinate, For target fluid particles a y-coordinate, For target fluid particles a z-coordinate, For the projected area, Therefore Centered on.

[0018] The velocity of the model node changes over time, as shown in the following formula: For nodes Search its neighborhood radius The particle set within : ; Calculate the average velocity of particles in its neighborhood: ; in, For target fluid particles a The position vector is represented as , For target fluid particles a The velocity vector at time t, It is the number of neighboring particles.

[0019] For nodes ,Record Over time The change in generates a curve: ; in, For nodes Velocity-time curve; Select SPH particles Record its speed. Over time The change in velocity is used to generate the SPH particle velocity change curve, as shown in the following formula: ; in, For target fluid particles a Velocity-time curve; Draw the final depositional profile of the debris flow along the central axis of the flume model, and filter out particles located near the x=0 plane: ; The particles are projected onto the yz plane to generate a scatter plot, and the height field of the projection plane is constructed using Kriging interpolation. Generate the final stacked cross-section of the central axis of the water tank model: ; in, This is a collection of particles located near the central axis at x=0. This represents the set of y-coordinates corresponding to the accumulation depth of the central axis profile. Construct a 3D morphological map of the debris flow deposition area and screen the data at the end of the simulation. All particles located within the accumulation region are represented by the following formula: ; in, A collection of particles for constructing the three-dimensional morphology of debris flow deposition areas; The accumulation region is discretized along a three-dimensional spatial grid with a grid size of [value missing]. For each grid node The particle density field at the grid nodes is calculated using the kernel function smoothing method: ; in, For cubic spline kernel functions, For smooth length; Extract the three-dimensional isosurface of the accumulation body and set a threshold. Defining debris flow deposits and air, its value is defined as follows: ,in This is the proportionality coefficient. After extracting the... The isosurface is approximated by constructing triangular facets within each voxel, passing through all voxels, and a three-dimensional model of the stacked morphology is drawn.

[0020] The impact force time history curves at specific nodes in the debris flow deposition area and the impact force distribution throughout the entire debris flow process are calculated to delineate the monitoring range within the deposition area. Define the grid nodes within the range as a set of monitoring points in sequence. : ; For each monitoring point Search its neighborhood radius The collection of SPH particles within: ; in, For monitoring points The set of neighborhood particles; Calculate the total impact force vector at each monitoring point at time t: ; in, This represents the vector of the total impact force experienced by each monitoring point. For particle mass, For particle acceleration; The magnitude of the impact force vector The changes over time are recorded to generate an impact force time history curve. ; Extract each monitoring point Throughout the simulation Maximum impact force: ; Maximum impact value of all monitoring points Mapped to its spatial location A spatial distribution cloud map of the maximum impact force throughout the entire process is generated using spatial interpolation methods.

[0021] Therefore, this invention proposes an experimental simulation method for debris flow flume based on SPH, the beneficial effects of which are as follows: (1) This invention does not require the construction of a physical water tank, thus avoiding the high economic investment in material procurement, device construction and maintenance in traditional physical experiments; at the same time, it completely eliminates the safety hazards such as device damage and personnel injury caused by the impact of high-concentration debris flow materials, and can confidently carry out simulations of extreme working conditions such as high flow rate and high concentration, thus solving the core pain point of "high risk and high consumption" in physical experiments.

[0022] (2) The present invention uses an improved solid fraction coupled friction-turbulence model and the SPH method to solve the problem, which can accurately capture the rheological characteristics of the solid and liquid phases of debris flow. Compared with the problem that physical experiments are easily affected by operational errors and environmental interference, the present invention ensures that the results have higher repeatability and credibility through parameterized control and mathematical modeling, and can accurately reflect the real process of debris flow, interaction and deposition.

[0023] (3) The present invention outputs multi-dimensional results such as the coverage area of ​​the accumulation area, velocity change curve, three-dimensional morphology diagram, and impact force distribution. It can not only provide quantitative data for the study of debris flow disaster mechanism, but also directly serve disaster prevention and mitigation practice—such as optimizing the layout of protection projects based on impact force distribution, predicting the scope of disaster impact based on accumulation morphology, and providing solid technical support for formulating scientific and accurate disaster prevention and mitigation measures.

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] Figure 1 This is a flowchart of an experimental simulation method for a debris flow flume based on SPH according to the present invention; Figure 2 This is a schematic diagram of the node velocity change curve in an embodiment of the present invention; Figure 3 This is a schematic diagram of the SPH particle velocity variation curve in an embodiment of the present invention; Figure 4 This is a schematic diagram of the final debris flow profile along the central axis of the flume model in an embodiment of the present invention. Figure 5 This is a top view of the debris flow deposition area in an embodiment of the present invention; Figure 6 This is a time-lapse curve of the impact force at a specific node in the debris flow deposition area in an embodiment of the present invention. Figure 7 This is a spatial distribution cloud map of the maximum impact force throughout the entire process in an embodiment of the present invention. Detailed Implementation

[0026] To make the technical solutions, advantages, and objectives of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0027] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0028] Example This invention provides a SPH-based simulation method for debris flow flume experiments. This method can accurately characterize the rheological properties and motion patterns of debris flows, providing a high-precision numerical simulation tool for debris flow flume experiments and an effective simulation method for numerical experiments. It also lays an important foundation for in-depth research on debris flow disaster mechanisms and the development of scientific and effective disaster prevention and mitigation measures. This invention selects a specific debris flow flume experiment case, and the specific steps are as follows: Figure 1 As shown: Step S1: According to the experimental requirements, input the size parameters of the water tank to construct the water tank model, define the accumulation area and divide the entire water tank model into a grid to generate the water tank model terrain. The dimensions of the water tank include the length of a single section. =2.0m, width =0.5m, material pool length =1m, initial depth of debris flow in the material pool =0.3m, number of segments =3. Tilt Angle Sequence and stacking area dimensions ( =0.05m; where, The length of the accumulation zone, The width of the accumulation area; The specific steps to generate the water tank model terrain are as follows: Step S11: Define an orthogonal coordinate system with the midpoint O(0,0,0) of the bottom edge of the first water tank as the origin; where, Positive direction is along the width of the water tank. A direction perpendicular to the wide side pointing towards the accumulation area is considered positive. The axis is considered positive when it is vertically upward. Step S12: Model the bottom surface of the single-section water tank and the bottom surface of the material pool; No. i The bottom of each water tank segment is rectangular. A local coordinate system is constructed with the midpoint of the bottom edge of each water tank segment as the origin. The coordinates of the four corner points in the local coordinate system are as follows: ; in, , , , The first i The coordinates of the four corner points of the bottom surface of the water tank in the local coordinate system; No. i The coordinates of the four points in the material pool section in the local coordinate system are as follows: ; in, , , , The first i The coordinates of the four points in the material pool section in the local coordinate system.

[0029] Step S13: Adjust the inclination angle of the water tank sections using a rotation matrix and connect each water tank section to the material pool; Taking the first section of the water tank as an example, the first section is around the midpoint of its bottom edge. of Axis rotation tilt angle The rotation matrix is: ; After rotation, the coordinates of the corner point are updated as follows: ; Midpoint of the end of segment 1 As the origin of the second paragraph Connect each section of the water tank, and so on. Connect the midpoint of the end of the third water tank. As the origin of the material pool The angle remains consistent with the previous section of the water tank, utilizing a rotation matrix. Connect the material pool to the last section of the water tank.

[0030] Step S14: Define the accumulation area and mesh the entire water tank model.

[0031] The accumulation area is located in Positive direction, vertex set D Defined as: ; in, x The x-coordinate of the accumulation zone y The vertical coordinate of the accumulation zone; Arrange the entire water tank according to the spacing Discretize the points to 0.05m into grid points, and use an adaptive grid at the junction of the three segments with different inclination angles. , k =0.1 to optimize boundary transition.

[0032] For the first and second grid segments ( ): ; For the second and third grid segments ( ): ; For the third segment and the material pool grid ( material pool angle ): ; Step S2: Input debris flow rheological parameters, define solid-liquid two-phase mixing density, and uniformly distribute solid particles and liquid particles according to solid volume fraction and material pool parameters to generate smooth particle hydrodynamic SPH particles of solid and liquid two phases. Debris flow rheological parameters include liquid phase density turbulence coefficient solid density Volume fraction The steps of SPH particle generation in solid-liquid two-phase smooth particle hydrodynamics are as follows: Step S21: Define the mixing density formula, as follows: ; Step S22: Based on the solid volume fraction Based on the material pool parameter data, evenly distribute solid and liquid phase particles. Material pool volume. Total number of particles According to volume fraction, there are 480 solid particles and 720 liquid particles, with a spacing of [missing information]. =0.5m.

[0033] Step S3: Based on the geometry of the water tank and the accumulation zone, apply repulsive forces to the water tank walls to set normal boundary conditions. Define the initial velocity field and hydrostatic pressure distribution as initial conditions. Use an improved solid fractional coupled friction-turbulence model and the SPH method to perform coupled solution to calculate the flow and interaction of debris flow. The specific steps are as follows: Step S31: Clean the walls of the water tank. Applying a repulsive force, the formula is as follows: ; in, For target fluid particles The total repulsive force from the wall, For boundary particles, For the set of boundary particles, The pressure of fluid particle a, For the pressure of boundary particle b, Let be the density of fluid particle a. Let b be the density of the boundary particle. For kernel function, Let be the wall normal vector. Let be the volume of the boundary particle b; Step S32: Define initial conditions, initial velocity field hydrostatic pressure distribution ;in, r For position vectors, denoted as , For mixed density, It is the acceleration due to gravity. The coordinates are in the vertical direction; Step S33: The improved solid-phase fractional coupled friction-turbulence model is coupled with the SPH method to calculate the motion process of debris flow; the formula for calculating the total base shear stress of the improved solid-phase fractional coupled friction-turbulence model is as follows: ; in, For normal stress, This represents the flow rate.

[0034] Step S4: Output simulation results, including the coverage area of ​​the debris flow deposition zone, the velocity variation curves of model nodes and SPH particles, the final deposition profile of the debris flow along the central axis of the flume model, the three-dimensional morphology of the deposition zone, the impact force curves of specific nodes throughout the process, and the distribution of the maximum impact force throughout the process.

[0035] The depositional area of ​​the debris flow is calculated as follows: Filtering particles in the accumulation zone : ; Project the particle onto the xy plane and calculate the projected area: ; in Therefore Centered on.

[0036] like Figure 2 Shown, sink The velocity curve of a node over time; for the node Search its neighborhood radius The particle set within : ; Calculate the average velocity of particles in its neighborhood: ; in, It is the number of neighboring particles.

[0037] For nodes ,Record Over time The changes in generate a curve.

[0038] like Figure 3 As shown, select distance Recent SPH particles For example, record its speed. Over time The change in velocity is used to generate the SPH particle velocity change curve, as shown in the following formula: ; like Figure 4 As shown, the final depositional profile of the debris flow along the central axis of the flume model is plotted, and particles located near the x=0 plane are selected using the following formula: ; The particles are projected onto the yz plane to generate a scatter plot, and the height field of the projection plane is constructed using Kriging interpolation. Generate the final stacked cross-section of the central axis of the water tank model: ; like Figure 5 As shown, a three-dimensional morphological map of the debris flow deposition area is constructed, and the simulation is screened at the end of the simulation. All particles located within the accumulation region are represented by the following formula: ; The accumulation region is discretized along a three-dimensional spatial grid with a grid size of [value missing]. .

[0039] For each grid node The particle density field at that location is calculated using the kernel function smoothing method, as shown in the following formula: ; in, For cubic spline kernel functions, For smooth length; Extract the three-dimensional isosurface of the accumulation and set a threshold. By extracting the required information... The isosurface is approximated by constructing triangular facets within each voxel, passing through all voxels, and a three-dimensional model of the stacked morphology is drawn.

[0040] like Figures 6-7 As shown, the monitoring area is delineated within the accumulation zone. Define the grid nodes within the range as a set of monitoring points in sequence. The monitoring points are spaced 0.05m apart, and there are a total of: There are 100 monitoring points; among them, the monitoring point set is 100. The formula is as follows: ; For each monitoring point Search its neighborhood radius The collection of SPH particles within: ; Calculate the total impact force vector at each monitoring point at time t: ; in, For particle mass, For particle acceleration, For smooth length The magnitude of the impact force vector The changes over time are recorded to generate an impact force time history curve. .

[0041] Extract each monitoring point Throughout the simulation Maximum impact force: ; Maximum impact value of all monitoring points Mapped to its spatial location A spatial distribution cloud map of the maximum impact force throughout the entire process is generated using spatial interpolation methods.

[0042] It is worth noting that all contents not described in detail in this invention are existing technologies and are well known to those skilled in the art.

[0043] Therefore, this invention provides a debris flow flume experimental simulation method based on SPH, which can significantly reduce experimental costs and safety risks, improve simulation accuracy and result reliability, efficiently support multi-dimensional research needs and provide comprehensive application data support, laying the foundation for debris flow disaster mechanism research and the formulation of scientific disaster prevention and mitigation measures.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for simulating debris flow flume experiments based on SPH, characterized in that, The specific steps are as follows: Step S1: According to the experimental requirements, input the size parameters of the water tank to construct the water tank model, define the accumulation area and divide the entire water tank model into a grid to generate the water tank model terrain. Step S2: Input debris flow rheological parameters, define solid-liquid two-phase mixing density, and uniformly distribute solid particles and liquid particles according to solid volume fraction and material pool parameters to generate smooth particle hydrodynamic SPH particles of solid and liquid two phases. Step S3: Based on the geometry of the water tank and the accumulation zone, apply repulsive force to the wall of the water tank to set normal boundary conditions. Define the initial velocity field and hydrostatic pressure distribution as initial conditions. Use the improved solid fractional coupled friction-turbulence model and the SPH method to perform coupled solution to calculate the flow and interaction of debris flow. Step S4: Output simulation results, including the coverage area of ​​the debris flow deposition zone, model node and SPH particle velocity change curves, the final deposition profile of the debris flow along the central axis of the flume model, the three-dimensional morphology of the deposition zone, the impact force curves of specific nodes throughout the process, and the maximum impact force distribution throughout the process.

2. The experimental simulation method for debris flow flume based on SPH according to claim 1, characterized in that, In step S1, the dimensional parameters of the water tank include the length of a single segment. ,width Material pool length Initial depth of debris flow in the material pool , number of segments Inclined angle sequence Dimensions of the stacking area ( ) and grid spacing ;in, The length of the accumulation zone, The width of the accumulation zone.

3. The experimental simulation method for debris flow flume based on SPH according to claim 2, characterized in that, The specific steps to generate the water tank model terrain are as follows: Step S11: Define an orthogonal coordinate system with the midpoint O of the bottom edge of the first water tank as the origin; where, Positive direction is along the width of the water tank. A direction perpendicular to the wide side pointing towards the accumulation area is considered positive. The axis is considered positive when it is vertically upward. Step S12: Model the bottom surface of the single-section water tank and the bottom surface of the material pool; Step S13: Adjust the inclination angle of the water tank sections using a rotation matrix and connect each water tank section to the material pool; Step S14: Define the accumulation area and mesh the entire water tank model.

4. The experimental simulation method for debris flow flume based on SPH according to claim 3, characterized in that, In step S12, the first i The bottom of each water tank segment is rectangular. A local coordinate system is constructed with the midpoint of the bottom edge of each water tank segment as the origin. The coordinates of the four corner points in the local coordinate system are as follows: ； in, , , , The first i The coordinates of the four corner points of the bottom surface of the water tank in the local coordinate system; No. i The coordinates of the four points in the material pool section in the local coordinate system are as follows: ； in, , , , The first i The coordinates of the four points in the material pool section in the local coordinate system.

5. The experimental simulation method for debris flow flume based on SPH according to claim 3, characterized in that, In step S13, the first i The segment wraps around the midpoint of its base. of Axis rotation tilt angle The rotation matrix is: ； After rotation, the coordinates of the corner point are updated as follows: ； The first i Midpoint of the end of the segment As the first i +1 segment origin Connect the various sections of the water tank; [The text abruptly ends here, likely due to an incomplete sentence or a formatting n The midpoint of the end of the segment flume As the origin of the material pool The angle remains consistent with the previous section of the water tank, utilizing a rotation matrix. Connect the material pool to the final water tank; where, For the first i The rotation matrix of the segment. For the first n The rotation matrix of the segment.

6. The experimental simulation method for debris flow flume based on SPH according to claim 3, characterized in that, In step S14, the accumulation area is located Positive direction, vertex set D Defined as: ； in, x The x-coordinate of the accumulation zone y The vertical coordinate of the accumulation zone; Arrange the entire water tank according to the spacing Discretized into grid points, with an adaptive mesh used at the junctions of multiple tilt angles. Perform grid division; where, k To adjust the coefficient, For the first i The grid spacing of the segment, For the first i The rotation angle of the segment.

7. The experimental simulation method for debris flow flume based on SPH according to claim 1, characterized in that, In step S2, the rheological parameters of the debris flow include the liquid phase density. turbulence coefficient Solid density and solid volume fraction The steps of SPH particle generation in solid-liquid two-phase smooth particle hydrodynamics are as follows: Step S21: Define the mixing density formula, as follows: ； Step S22: Based on the solid volume fraction Based on the material pool parameter data, solid and liquid phase particles are evenly distributed.

8. The experimental simulation method for debris flow flume based on SPH according to claim 1, characterized in that, In step S3, the specific steps are as follows: Step S31: Clean the walls of the water tank. Applying a repulsive force, the formula is as follows: ； in, For target fluid particles The total repulsive force from the wall, For boundary particles, For the set of boundary particles, For target fluid particles Pressure For the pressure of boundary particle b, For target fluid particles density, Let b be the density of the boundary particle. For kernel function, Let be the wall normal vector. Let be the volume of the boundary particle b; Step S32: Define initial conditions, initial velocity field hydrostatic pressure distribution ;in, r For position vectors, For mixed density, It is the acceleration due to gravity. The vertical coordinates of the accumulation zone; Step S33: The improved solid-phase fractional coupled friction-turbulence model is coupled with the SPH method to calculate the motion process of debris flow; the formula for calculating the total base shear stress of the improved solid-phase fractional coupled friction-turbulence model is as follows: ； ； ； in, For normal stress, For the magnitude of the flow velocity, Solid volume fraction The relevant dynamic friction coefficient, The coefficient of friction of the substrate. To adjust the parameters, Solid volume fraction The relevant dynamic turbulence coefficients, To adjust the parameters.

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