A simulation method for the debris flow interception capacity of a permeable retaining dam based on a two-phase SPH model

Abstract

The present invention provides a simulation method for the debris flow retention capacity of a permeable retaining dam based on a two-phase SPH model, comprising the following steps: 1) Generate a control particle chain of the retaining dam according to the axial direction of the layout position of the retaining dam and the elevation of the dam crest of the retaining dam, and apply the retaining effect of the retaining dam to the debris flow SPH particles; 2) Determine the elevation level of the debris flow deposition within the influence domain of the control particle chain of the retaining dam at each time step; 3) Compare the elevation level of the debris flow deposition within the influence domain of the control particle chain with the elevation of the dam crest of the retaining dam to determine whether the retaining potential of the retaining dam is fully exerted; 4) By comparing the back-silting surface line of the debris flow with the actual deposition situation of the debris flow, treat a part of the debris flow retained by the retaining dam as the terrain, and update the particle information and terrain information in the new time step; 5) Define an approximate friction reduction coefficient on the surface of the debris flow deposition body to calculate the dynamic process of the debris flow after the retaining dam is overtopped.

Description

Technical Field

[0001] The present invention relates to the technical field of geological disaster simulation, and particularly relates to a method for simulating the debris flow retention capacity of a permeable retaining dam based on a two-phase SPH model. Background Art

[0002] The smoothed particle hydrodynamics method is a typical meshless method, which is applicable to the simulation of geological disaster processes such as landslides and debris flows. A permeable retaining dam is a widely used debris flow and sediment separation disaster reduction facility. How to scientifically and effectively evaluate its disaster reduction efficiency by using numerical simulation methods is a key problem to be solved. Under the framework of the depth integration control method, the simulation of the debris flow retention effect of a permeable retaining dam is usually achieved by defining a permeable boundary. Such a boundary realizes the simulation of the permeable sand retention effect by adopting different velocity constraint conditions for the solid and liquid phases inside the debris flow respectively. However, there is no effective consideration of the influence on the debris flow movement process after the retaining dam reaches the designed retention capacity, especially after overtopping. Summary of the Invention

[0003] Aiming at the blank of the prior art, the present invention compares the back-silting curve with the digital simulation silting result, and considers the partially retained debris flow body as an equivalent terrain under the framework of the depth integration control method, so as to realize the efficient simulation of the debris flow retention effect of the permeable retaining dam before and after overtopping, and can effectively support the application and development of such disaster reduction measures in practical engineering.

[0004] The technical problem to be solved by the present invention is to overcome the limitation that the current SPH method cannot effectively analyze the debris flow retention effect of a permeable retaining dam after overtopping, and proposes a method for simulating the debris flow retention capacity of a permeable retaining dam based on a two-phase SPH model.

[0005] It includes the following steps: 1) Generate a dam control particle chain according to the axis direction of the dam layout position and the elevation of the dam crest of the retaining dam, and apply the retaining effect of the retaining dam to the debris flow SPH particles; 2) Determine the elevation level of the debris flow deposition within the influence domain of the dam control particle chain at each time step; 3) Compare the elevation level of the debris flow deposition within the influence domain of the control particle chain with the elevation of the dam crest of the retaining dam to determine whether the retaining potential of the retaining dam is fully exerted. If the determination in step 3 is no, then continue step 2 in the next time step. If the determination in step 3 is yes, then enter step 4; 4) By comparing the backflow surface line of the debris flow with the actual deposition situation of the debris flow, treat a part of the debris flow retained by the retaining dam as terrain, and update the particle information and terrain information in the new time step; 5) Define an approximate friction reduction coefficient on the surface of the debris flow deposition body and calculate the dynamic process of the debris flow after the retaining dam is overtopped. The present invention analyzes the retaining effect of the debris flow retaining dam by constructing a dam control particle chain, especially analyzes the interaction between the debris flow and the retaining dam after the retaining dam is full and the debris flow overtopps the dam. By comparing the backflow surface line of the debris flow with the simulated accumulation situation of the debris flow, an equivalent terrain after the complete deposition of the retaining dam is established, realizing an efficient simulation of the retaining effect of the debris flow retaining dam before and after overtopping.

[0006] The technical solution specifically adopted by the present invention to solve its technical problems is:

[0007] A method for simulating the debris flow retaining capacity of a permeable retaining dam based on a two-phase SPH model, including the following steps:

[0008] Step 1: Generate a dam control particle chain according to the axis direction of the dam layout position and the elevation of the dam crest of the retaining dam, and apply the retaining effect of the retaining dam to the debris flow SPH particles;

[0009] Step 2: Determine the elevation level of the debris flow deposition within the influence domain of the dam control particle chain at each time step;

[0010] Step 3: Compare the elevation level of the debris flow deposition within the influence domain of the control particle chain with the elevation of the dam crest of the retaining dam to determine whether the retaining potential of the retaining dam is fully exerted. If the determination in step 3 is no, then continue step 2 in the next time step. If the determination in step 3 is yes, then enter step 4;

[0011] Step 4: By comparing the backflow surface line of the debris flow with the actual deposition situation of the debris flow, treat a part of the debris flow retained by the retaining dam as terrain, and update the particle information and terrain information in the new time step;

[0012] Step 5: Define an approximate friction reduction coefficient on the surface of the debris flow deposition body and calculate the dynamic process of the debris flow after the retaining dam is overtopped.

[0013] Further, the axis direction of the retaining dam layout position in Step 1 is determined by two axis control points ACP1(x1, y1) and ACP2(x2, y2). Combining with the top elevation of the retaining dam top_chkdam, a retaining dam control particle chain chk_list(:, 1:4) is generated to apply the retaining effect of the retaining dam on the debris flow SPH particles; it includes the following steps:

[0014] Step 11: Determine the axis direction vector according to the coordinates (x1, y1) and (x2, y2) of the two axis control points ACP1 and ACP2 and the normal vector : The selection of the axis control points ACP1 and ACP2 should satisfy the right-hand rule, so that the normal vector points to the upstream direction of the debris flow, and the calculation formula of the axis direction vector is as follows:

[0015]

[0016] In the formula, is the modulus length of the axis direction vector ; the calculation formula of the normal vector is as follows:

[0017]

[0018] Step 12: According to the top elevation of the retaining dam top_chkdam and the distance between the retaining dam control points deta_chkdam, calculate the horizontal coordinate position chk_list(:, 1:2), the surface elevation information chk_list(:, 3) and the retaining dam height information chk_list(:, 4) of the retaining dam control particle chain chk_list(:, 1:4); the initial number of generated retaining dam control points The calculation formula for the control particle chain chk_list(i, 1:4) of the i-th retaining dam control point is as follows:

[0019] 1) Horizontal coordinate position chk_list(i, 1:2):

[0020]

[0021] 2) The surface elevation information chk_list(:, 3) is obtained by calling the terrain module topo_ele(,) with the input horizontal coordinate position chk_list(i, 1:2): chk_list(i, 3) = topo_ele(chk_list(i, 1), chk_list(i, 2));

[0022] 3) The height information of the retaining dam chk_list(:,4). By comparing the actual ground elevation and the dam crest elevation of the position where the particles controlled by the retaining dam are arranged, the height information of the retaining dam corresponding to the particles controlled by the retaining dam is determined. The calculation formula is as follows:

[0023] chk_list(i,4) = top_chkdam - chk_list(i,3)

[0024] Exclude the particles with negative calculated values in the dam height chk_list(i,4) of the particles controlled by the retaining dam in the above calculation results, and obtain the updated particle chain chk_list(:,1:4) of the particles controlled by the retaining dam, the axis length axis_len_chkdam of the retaining dam crest, and the number num_chkdam of the finally generated control points of the retaining dam;

[0025] Step 13: Take the particle chain chk_list(:,1:4) of the particles controlled by the retaining dam as the boundary virtual particles and bring them into the debris flow two-phase SPH model for calculation, applying the retaining boundary effect; do not make special treatment for the water particles to simulate the permeable effect, and eliminate the normal velocity of the soil particles perpendicular to the boundary to realize the retaining effect on the soil.

[0026] Furthermore, in step 2, the influence distance infwid_chk of the sedimentation elevation in front of the retaining dam is defined to determine the sedimentation elevation calculation area, thereby realizing the calculation of the debris flow sedimentation elevation level within the influence domain of the particle chain controlled by the retaining dam; it includes the following steps:

[0027] Step 21: Traverse the SPH particles in the solution domain to obtain the direction vector as_vec(:) formed by the axis control point ACP1(x1,y1) and the SPH particles:

[0028]

[0029] In the formula, xs(1) and xs(2) are the x and y coordinates of the SPH particles respectively;

[0030] Step 22: Calculate the projection values as_pro_atn and as_pro_avn of the direction vector as_vec(:) on the axis direction vector and the normal vector :

[0031]

[0032] In the formula, vec_dot(,) is the vector dot product operator;

[0033] Step 23: Determine whether the SPH particles are within the sedimentation elevation calculation area based on the projection values as_pro_atn and as_pro_avn, as well as the axis length axis_len_chkdam of the check dam crest and the influence distance infwid_chk of the sedimentation elevation in front of the check dam, and then calculate the average sedimentation elevation depo_dep_ave of the particles:

[0034] depo_dep_ave = average(hs(:) + z_topo(:))

[0035] In the formula, average() is the mean function, hs(:) is the debris flow depth value carried by the SPH particles, and z_topo(:) is the elevation value of the position where the SPH particles are located.

[0036] Further, in Step 3, compare the average sedimentation elevation depo_dep_ave of the debris flow in front of the check dam calculated in Step 2 with the elevation top_chkdam of the check dam crest. If depo_dep_ave < top_chkdam, the storage potential of the check dam is not fully utilized, and continue to calculate the average sedimentation elevation of the debris flow in front of the check dam in Step 2 at the next time step; if depo_dep_ave ≥ top_chkdam, the storage potential of the check dam is fully utilized, and enter Step 4.

[0037] Further, in Step 4, according to the back-silting surface line of the debris flow and the actual sedimentation situation of the debris flow, treat a part of the debris flow intercepted by the check dam as terrain, and update the particle information and terrain information in the new time step; it includes the following steps:

[0038] Step 41: Calculate the vertical distance dist_s(:) of the debris flow SPH particles from the check dam. For the i-th SPH particle, the calculation formula is as follows:

[0039] 1) Calculate the vector vec_S2A(:) from the i-th SPH particle to the axis control point ACP1:

[0040]

[0041] In the formula, xs(1), xs(2), x1, and y1 are the horizontal and vertical coordinates of the SPH particle and the axis control point ACP1 respectively;

[0042] 2) Calculate the distance dist_s(i) from the i-th SPH particle to the check dam axis:

[0043]

[0044] In the formula, vec_dot(,) is the vector dot product operator, is the normal vector of the axis of the retaining dam;

[0045] Step 42: Calculate the theoretical back-silting elevation depo_theo_s(:) of the debris flow retaining dam. For the i-th SPH particle, the calculation formula is as follows:

[0046]

[0047] In the formula, θ is the average slope of the debris flow, is the equivalent internal friction angle of the debris flow, dist_s(i) is the vertical distance from the debris flow SPH particle to the retaining dam calculated in the previous step, and max(chk_list(:,4)) is the maximum value of the retaining dam height information;

[0048] Step 43: Compare the theoretical back-silting elevation depo_theo_s(:) of the debris flow SPH particles with the actual siltation elevation depo_real_s(:) of the debris flow to obtain the updated surface elevation information z_topo(:) and the debris flow depth information hs(:). For the i-th debris flow SPH particle, the calculation steps are as follows:

[0049] 1) Calculate the actual siltation elevation depo_real_s(i) of the debris flow. The calculation formula is as follows:

[0050] depo_real_s(i) = hs(i) + z_topo(i)

[0051] In the formula, z_topo(i) is the elevation value of the position where the SPH particle is located;

[0052] 2) Compare the actual siltation elevation depo_real_s(:) of the debris flow with the theoretical back-silting elevation depo_theo_s(:). For those with the actual siltation elevation lower than the theoretical back-silting elevation, convert the actual siltation elevation of the SPH particle to the terrain elevation:

[0053] hs(i) = 0

[0054] z_topo(i) = depo_real_s(i);

[0055] For those with the actual siltation elevation higher than the theoretical back-silting elevation, take the theoretical back-silting elevation as the updated surface elevation, and take the difference between the actual siltation elevation higher than the theoretical back-silting elevation as the updated debris flow depth value hs(:) carried by the SPH particle:

[0056] hs(i) = depo_theo_s(i) - z_topo(i)

[0057] z_topo(i) = depo_theo_s(i).

[0058] Furthermore, in step 5, the approximate friction coefficient reduction coefficient fri_coe_redu of the debris flow deposition body surface is defined, and the approximate friction coefficient values fri_coe_mesh(:) of the background grids corresponding to the debris flow accumulation area are reduced by the approximate friction coefficient reduction coefficient fri_coe_redu, and then the debris flow dynamic process calculation after the retaining dam is overtopped is carried out. The calculation formula is as follows:

[0059] fri_coe_mesh(:) = fri_coe_mesh(:) * fri_coe_redu.

[0060] In addition, a simulation system for the debris flow retention capacity of a permeable retaining dam based on a two-phase SPH model includes a memory, a processor, and computer program instructions stored on the memory and executable by the processor. When the processor runs the computer program instructions, the above-mentioned method steps can be realized.

[0061] Compared with the prior art, the present invention and its preferred solutions aim at the limitation that the current SPH method cannot effectively analyze the debris flow retention effect of a permeable retaining dam after overtopping, and propose a simulation method for the debris flow retention capacity of a permeable retaining dam based on a two-phase SPH model. On the basis of the conventional simulation method for the debris flow retention effect of a permeable retaining dam by defining a permeable boundary, by comparing the back-silting curve with the digital simulation deposition result, and considering a part of the retained debris flow body as an equivalent terrain under the framework of the depth integration control method, the efficient simulation of the debris flow retention effect of a permeable retaining dam before and after overtopping is realized, which can effectively support the application and development of such disaster reduction measures in practical projects. Description of the Drawings

[0062] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments:

[0063] Figure 1 is the flowchart of the method of the embodiment of the present invention.

[0064] Figure 2 is a schematic diagram of a permeable debris flow retaining dam in the embodiment of the present invention.

[0065] Figure 3 is a schematic diagram of updating calculation information by comparing the debris flow back-silting surface line with the actual deposition situation in the embodiment of the present invention. Detailed Embodiments

[0066] To make the features and advantages of this patent more obvious and understandable, specific embodiments are given below and described in detail as follows:

[0067] It should be noted that the following detailed description is illustrative and aims to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0068] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0069] Aiming at the limitation that the current SPH method cannot effectively analyze the debris flow interception effect of a permeable debris flow retaining dam after overtopping, the present invention proposes a simulation method for the debris flow interception capacity of a permeable debris flow retaining dam based on a two-phase SPH model. On the basis of the conventional SPH debris flow simulation permeable boundary method, by comparing the back-silting curve with the digital model silting result and considering a part of the intercepted debris flow body as an equivalent terrain under the framework of the depth integration control method, the efficient simulation of the debris flow interception effect of the permeable debris flow retaining dam before and after overtopping can be realized, which can effectively support the application and development of such disaster reduction measures in actual projects. The specific implementation flowchart is as shown in the appendix Figure 1 as follows. It mainly includes the following 5 steps:

[0070] Step 1: According to the axis direction of the retaining dam layout position and the crest elevation of the retaining dam, generate a retaining dam control particle chain and apply the retaining effect of the retaining dam to the debris flow SPH particles.

[0071] Step 2: Determine the debris flow siltation elevation level within the influence domain of the retaining dam control particle chain at each time step.

[0072] Step 3: By comparing the debris flow siltation elevation level within the influence domain of the control particle chain with the crest elevation of the retaining dam, determine whether the retaining potential of the retaining dam is fully exerted. If the determination in Step 3 is no, then continue with Step 2 in the next time step. If the determination in Step 3 is yes, then enter Step 4.

[0073] Step 4: By comparing the debris flow back-silting surface line with the actual debris flow siltation situation, treat a part of the debris flow intercepted by the retaining dam as terrain, and update the particle information and terrain information in the new time step.

[0074] Step 5: Define an approximate friction reduction coefficient for the debris flow siltation body surface and calculate the debris flow dynamic process after the retaining dam is overtopped.

[0075] Select an actual permeable debris flow retaining dam project (seeFigure 2 ), according to the method flow ( Figure 1 ), a detailed introduction and description are as follows:

[0076] Step 1: The axis direction of the location of the retaining dam is determined by two axis control points ACP1(280.0, 480.0) and ACP2(190.0, 530.0). Combining with the top elevation of the retaining dam top_chkdam = 260m, a control particle chain chk_list(:, 1:4) of the retaining dam is generated to exert the retaining effect of the retaining dam on the debris flow SPH particles. It includes the following steps:

[0077] S1.1: Determine the axis direction vector and the normal vector Note that the selection of the axis control points ACP1 and ACP2 should satisfy the right-hand rule, so that the normal vector points to the upstream direction of the debris flow, and the axis direction vector is calculated as follows:

[0078]

[0079] In the formula, is the modulus length of the axis direction vector . The normal vector is calculated as follows:

[0080]

[0081] S1.2: According to the top elevation of the retaining dam top_chkdam and the distance between the retaining dam control points deta_chkdam, calculate the horizontal coordinate positions chk_list(:, 1:2), the surface elevation information chk_list(:, 3), and the retaining dam height information chk_list(:, 4) of the control particle chain chk_list(:, 1:4) of the retaining dam. The initial number of generated retaining dam control points For the control particle chain chk_list(2, 1:4) of the second retaining dam control point, the calculation formula is as follows:

[0082] 1) Horizontal coordinate positions chk_list(2, 1:2):

[0083]

[0084]

[0085] 2) The surface elevation information chk_list(:, 3) is obtained by calling the terrain module topo_ele(,) with the input horizontal coordinate positions chk_list(i, 1:2): chk_list(2, 3) = topo_ele(chk_list(i, 1), chk_list(i, 2)) = 241.904.

[0086] 3) For the height information of the retaining dam chk_list(:, 4), by comparing the actual surface elevation and the dam crest elevation at the position where the retaining dam control particles are arranged, the height information of the retaining dam corresponding to the retaining dam control particles is determined. The calculation formula is as follows:

[0087]

[0088] Particles with negative calculated values in the dam height chk_list(i, 4) of the retaining dam control particles in the above calculation results are removed, obtaining the updated retaining dam control particle chain chk_list(:, 1:4), the axis length of the retaining dam crest axis_len_chkdam = 100.0 m, and the final number of control points of the retaining dam generated num_chkdam = 48.

[0089] S1.3: Take the retaining dam control particle chain chk_list(1:48, 1:4) as boundary virtual particles and bring them into the debris flow two-phase SPH model for calculation, applying the retaining boundary effect. No special treatment is done to the water body particles to achieve the simulation of the permeable effect, and the normal velocity of the soil particles perpendicular to the boundary is eliminated to achieve the retaining effect on the soil.

[0090] Step 2: Determine the deposition elevation calculation area by defining the influence distance of the deposition elevation in front of the retaining dam infwid_chk = 10 m, and then calculate the debris flow deposition elevation level within the influence domain of the retaining dam control particle chain. It includes the following steps:

[0091] S2.1: Traverse the SPH particles in the solution domain to obtain the direction vector as_vec(:) formed by the axis control point ACP1(x1, y1) and the SPH particles. Taking the SPH particle with coordinates (200, 530) as an example:

[0092]

[0093] In the formula, xs(1) and xs(2) are the x and y coordinates of the SPH particle respectively.

[0094] S2.2: Calculate the projection values as_pro_atn and as_pro_avn of the direction vector as_vec(:) on the axis direction vector and the normal vector :

[0095]

[0096] In the formula, vec_dot(,) is the vector dot product operator.

[0097] S2.3: Determine whether the SPH particles are within the sedimentation elevation calculation area through the projection values as_pro_atn, as_pro_avn, the axis length of the check dam axis_len_chkdam = 100.0 m, and the influence distance of the sedimentation elevation in front of the check dam infwid_chk = 10 m. The determination conditions are as follows:

[0098]

[0099] When all of the above 4 conditions are met, the SPH particle is within the sedimentation elevation calculation area, and calculate the average sedimentation elevation depo_dep_ave of all particles that meet the conditions:

[0100] depo_dep_ave = average(hs(:)+z_topo(:)) = 261 m (8)

[0101] In the formula, average() is the mean function, hs(:) is the debris flow depth value carried by the SPH particle, and z_topo(:) is the elevation value of the location where the SPH particle is located.

[0102] Step 3: Compare the average sedimentation elevation of the debris flow in front of the check dam depo_dep_ave = 261 m calculated in Step 2 with the top elevation of the check dam top_chkdam = 260 m. If depo_dep_ave ≥ top_chkdam, the check dam's storage potential is fully exerted, and proceed to Step 4.

[0103] Step 4: According to the debris flow back-silting surface line and the actual sedimentation situation of the debris flow, treat a part of the debris flow intercepted by the check dam as terrain, and update the particle information and terrain information in the new time step (see Figure 3 ). It includes the following steps:

[0104] S4.1: Calculate the vertical distance dist_s(:) of the debris flow SPH particle from the check dam. For an SPH particle with coordinates (310, 640), the calculation formula is as follows:

[0105] 1) Calculate the vector vec_S2A(:) from this SPH particle to the axis control point ACP1:

[0106]

[0107] Wherein, xs(1), xs(2), x1, and y1 are respectively the abscissa and ordinate of the SPH particle and the axis control point ACP1.

[0108] 2) Calculate the distance dist_s(i) from the SPH particle to the axis of the retaining dam:

[0109]

[0110] Wherein, vec_dot(,) is the vector dot product operator, is the normal vector of the axis of the retaining dam.

[0111] S4.2: Calculate the theoretical back-silting elevation depo_theo_s(:) of the debris flow retaining dam. For this SPH particle, the calculation formula is as follows:

[0112] depo_theo_s(i)

[0113] = (cos 30°tan45° - sin30°) / tan 2 (45° - 0.5*45°)*154.434 + 260

[0114] = 589.462m (11)

[0115] Wherein, θ is the average slope of the debris flow, is the equivalent internal friction angle of the debris flow, dist_s(i) is the vertical distance from the debris flow SPH particle to the retaining dam calculated in the previous step, and max(chk_list(:,4)) is the maximum value of the retaining dam height information.

[0116] S4.3: Compare the theoretical back-silting elevation depo_theo_s(:) of the debris flow SPH particle and the actual back-silting elevation depo_real_s(:) of the debris flow to obtain the updated surface elevation information z_topo(:) and the debris flow depth information hs(:). For this debris flow SPH particle, the calculation steps are as follows:

[0117] 1) Calculate the actual back-silting elevation depo_real_s(i), and the calculation formula is as follows:

[0118] depo_real_s(i) = hs(i) + z_topo(i) = 20 + 580 = 600m (12)

[0119] Wherein, z_topo(:) is the elevation value at the position of the SPH particle.

[0120] 2) Compare the actual deposition elevation of debris flow depo_real_s(:) with the theoretical elevation of siltation backfill depo_theo_s(:). For those with the actual deposition elevation higher than the theoretical elevation of siltation backfill, take the theoretical elevation of siltation backfill as the updated surface elevation, and take the difference between the actual deposition elevation and the theoretical elevation of siltation backfill as the debris flow depth value hs(:) carried by the updated SPH particles. The calculation formula is as follows:

[0121]

[0122] Step 5: Define the reduction coefficient fri_coe_redu of the approximate friction coefficient on the surface of the debris flow deposition body, and calculate the dynamic process of the debris flow after overtopping the retaining dam after reducing the approximate friction coefficient value fri_coe_mesh(:) of the background grid corresponding to the debris flow accumulation area by the approximate friction coefficient reduction coefficient fri_coe_redu = 0.1. The calculation formula is as follows:

[0123]

[0124] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0125] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of the processes and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for realizing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0126] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured product including instruction means, and the instruction means realizes the functions in one process Figure 1 one process or multiple processes and / or blocks Figure 1The functions specified in one or more boxes.

[0127] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide for implementing the steps of the functions specified in one or more processes and / or boxes Figure 1 One process or more processes and / or boxes Figure 1 The steps of the functions specified in one or more boxes.

[0128] As described above, it is only the preferred embodiment of the present invention, and it is not a limitation to the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

[0129] This patent is not limited to the above best implementation manner. Anyone inspired by this patent can obtain various other forms of a method for simulating the debris flow retention capacity of a permeable retaining dam based on a two-phase SPH model. All equal changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by this patent.

Claims

1. A simulation method for the debris flow retention capacity of a permeable retaining dam based on a two-phase SPH model, characterized in that, Including the following steps: Step 1: According to the axis direction of the retaining dam layout position and the elevation of the retaining dam crest, generate a control particle chain for the retaining dam, and apply the retaining effect of the retaining dam to the debris flow SPH particles; Step 2: Determine the elevation level of the debris flow deposition within the influence domain of the retaining dam control particle chain at each time step; Step 3: By comparing the elevation level of the debris flow deposition within the influence domain of the control particle chain with the elevation of the retaining dam crest, determine whether the retaining potential of the retaining dam is fully exerted. If the determination in Step 3 is no, then continue with Step 2 in the next time step. If the determination in Step 3 is yes, then proceed to Step 4; Step 4: By comparing the actual deposition elevation of the debris flow with the theoretical elevation of back-silting, for the debris flow SPH particles with an actual deposition elevation lower than the theoretical elevation of back-silting, convert their actual deposition elevation to the terrain elevation; for the debris flow SPH particles with an actual deposition elevation higher than the theoretical elevation of back-silting, use the theoretical elevation of back-silting as the updated surface elevation, and use the difference between the actual deposition elevation and the theoretical elevation of back-silting as the updated debris flow depth value. Update the particle information and terrain information in the new time step; Step 5: Define an approximate friction reduction coefficient for the surface of the debris flow deposition body and calculate the dynamic process of the debris flow after the retaining dam is overtopped.

2. The method for simulating the debris flow retaining capacity of a permeable retaining dam based on a two-phase SPH model according to claim 1, characterized in that: In Step 1, the axis direction of the retaining dam layout position is determined by two axis control points ACP1(x1, y1) and ACP2(x2, y2). Combining with the elevation of the retaining dam crest top_chkdam, generate a control particle chain chk_list(:, 1:4) for the retaining dam, and apply the retaining effect of the retaining dam to the debris flow SPH particles; including the following steps: Step 11: Determine the axis direction vector based on the coordinates (x1, y1) and (x2, y2) of two axis control points ACP1 and ACP2 and the normal vector The selection of axis control points ACP1 and ACP2 should satisfy the right-hand rule, such that the normal vector points to the upstream direction of the debris flow, and the calculation formula for the axis direction vector is as follows: In the formula, is the modulus of the axial direction vector ; the calculation formula of the normal vector is as follows: Step 12: Based on the top elevation of the retaining dam top_chkdam and the distance between the control points of the retaining dam deta_chkdam, calculate the horizontal coordinate positions chk_list(:,1:2), the surface elevation information chk_list(:,3), and the height information of the retaining dam chk_list(:,4) of the control particle chain chk_list(:,1:4) of the retaining dam; the initial number of generated control points of the retaining dam The calculation formula for the control particle chain chk_list(i,1:4) of the i-th control point of the retaining dam is as follows: 1) Horizontal coordinate position chk_list(i, 1:2): 2) The surface elevation information chk_list(:, 3) is obtained by calling the terrain module topo_ele(,) with the input horizontal coordinate position chk_list(i, 1:2): chk_list(i, 3) = topo_ele(chk_list(i, 1), chk_list(i, 2)); 3) The retaining dam height information chk_list(:, 4), by comparing the actual surface elevation of the retaining dam control particle layout position with the elevation of the dam crest, determine the retaining dam height information corresponding to the retaining dam control particle. The calculation formula is as follows: chk_list(i, 4) = top_chkdam - chk_list(i, 3) Eliminate the particles with a negative calculated value in the dam height chk_list(i, 4) of the retaining dam control particles in the above calculation results to obtain the updated retaining dam control particle chain chk_list(:, 1:4), the axis length axis_len_chkdam of the retaining dam crest, and the final number of retaining dam control points num_chkdam generated; Step 13: Take the control particle chain chk_list(:,1:4) of the retaining dam as boundary virtual particles and bring them into the debris flow two-phase SPH model for calculation to apply the retaining boundary effect; do not perform special treatment on the water particles to simulate the water-permeable effect, and eliminate the normal velocity of the soil particles perpendicular to the boundary to achieve the retaining effect on the soil.

3. A method for simulating the debris flow retaining capacity of a water-permeable retaining dam based on a two-phase SPH model according to claim 2, characterized in that: In step 2, the influence distance infwid_chk of the sedimentation elevation in front of the retaining dam is defined to determine the sedimentation elevation calculation area, thereby realizing the calculation of the debris flow sedimentation elevation level within the influence domain of the control particle chain of the retaining dam; it includes the following steps: Step 21: Traverse the SPH particles in the solution domain to obtain the direction vector as_vec(:) formed by the axis control point ACP1(x1,y1) and the SPH particles: In the formula, xs(1) and xs(2) are the x and y coordinates of the SPH particle respectively; Step 22: Calculate the projection values as_pro_atn and as_pro_avn of the direction vector as_vec(:) on the axis direction vector and the normal vector : as_pro_atn and as_pro_avn In the formula, vec_dot(,) is the vector dot product operator; Step 23: Determine whether the SPH particle is within the sedimentation elevation calculation area through the projection values as_pro_atn, as_pro_avn, the axis length axis_len_chkdam of the retaining dam crest, and the influence distance infwid_chk of the sedimentation elevation in front of the retaining dam, and then calculate the average sedimentation elevation depo_dep_ave of the particle: depo_dep_ave = average(hs(:)+z_topo(:)) In the formula, average() is the mean function, hs(:) is the debris flow depth value carried by the SPH particle, and z_topo(:) is the elevation value of the position where the SPH particle is located.

4. A simulation method for the debris flow retention capacity of a permeable retaining dam based on a two-phase SPH model according to claim 3, characterized in that: In step 3, compare the average sedimentation elevation depo_dep_ave of the debris flow in front of the retaining dam calculated in step 2 with the elevation top_chkdam of the retaining dam crest. If depo_dep_ave < top_chkdam, the retaining potential of the retaining dam is not fully exerted, and continue to calculate the average sedimentation elevation of the debris flow in front of the retaining dam in step 2 at the next time step; if depo_dep_ave ≥ top_chkdam, the retaining potential of the retaining dam is fully exerted, and enter step 4.

5. A method for simulating the debris flow retaining capacity of a water-permeable retaining dam based on a two-phase SPH model according to claim 4, characterized in that: In step 4, according to the debris flow back-silting surface line and the actual debris flow sedimentation situation, part of the debris flow retained by the retaining dam is treated as terrain, and the particle information and terrain information are updated in the new time step; It includes the following steps: Step 41: Calculate the vertical distance dist_s(:) of the debris flow SPH particle from the retaining dam. For the i-th SPH particle, the calculation formula is as follows: 1) Calculate the vector vec_S2A(:) from the i-th SPH particle to the axis control point ACP1: Wherein, xs(1), xs(2), x1, and y1 are respectively the horizontal and vertical coordinates of the SPH particle and the axis control point ACP1; 2) Calculate the distance dist_s(i) from the i-th SPH particle to the axis of the retaining dam: wherein, vec_dot(,) is a vector dot product operator, is the normal vector of the axis of the retaining dam; Step 42: Calculate the theoretical elevation of sediment deposition depo_theo_s(:) of the debris flow retaining dam. For the i-th SPH particle, the calculation formula is as follows: where θ is the average slope gradient of debris flow, is the equivalent internal friction angle of debris flow, dist_s(i) is the vertical distance from the SPH particle of debris flow calculated in the previous step to the retaining dam, and max(chk_list(:,4)) is the maximum value of the retaining dam height information; Step 43: Compare the theoretical elevation of sediment deposition depo_theo_s(:) of the debris flow SPH particles with the actual elevation of sediment deposition depo_real_s(:) of the debris flow to obtain the updated surface elevation information z_topo(:) and the debris flow depth information hs(:). For the i-th debris flow SPH particle, the calculation steps are as follows: 1) Calculate the actual elevation of sediment deposition depo_real_s(i) of the debris flow. The calculation formula is as follows: depo_real_s(i) = hs(i) + z_topo(i) Wherein, z_topo(i) is the elevation value at the position of the SPH particle; 2) Compare the actual elevation of sediment deposition depo_real_s(:) of the debris flow with the theoretical elevation of sediment deposition depo_theo_s(:). For those with the actual elevation of sediment deposition lower than the theoretical elevation of sediment deposition, convert the actual elevation of sediment deposition of the SPH particle into the topographic elevation: hs(i) = 0 z_topo(i) = depo_real_s(i); For those with the actual elevation of sediment deposition higher than the theoretical elevation of sediment deposition, use the theoretical elevation of sediment deposition as the updated surface elevation, and use the difference between the actual elevation of sediment deposition higher than the theoretical elevation of sediment deposition as the updated debris flow depth value hs(:) carried by the SPH particle: hs(i) = depo_theo_s(i) - z_topo(i) z_topo(i) = depo_theo_s(i).

6. A method for simulating the debris flow retention capacity of a permeable retaining dam based on a two-phase SPH model according to claim 5, characterized in that: Define the approximate friction coefficient reduction coefficient fri_coe_redu on the surface of the debris flow deposition body in step 5, and reduce the approximate friction coefficient value fri_coe_mesh(:) of the background grid corresponding to the debris flow accumulation area by the approximate friction coefficient reduction coefficient fri_coe_redu, and then calculate the debris flow dynamic process after the retaining dam is overtopped. The calculation formula is as follows: fri_coe_mesh(:) = fri_coe_mesh(:) * fri_coe_redu.

7. A simulation system for the debris flow retention capacity of a permeable retaining dam based on a two-phase SPH model, characterized in that: It includes a memory, a processor, and computer program instructions stored on the memory and capable of being run by the processor. When the processor runs the computer program instructions, it can implement the steps described in any one of claims 1-6.

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