Channel debris flow blocking and protecting pile forest

Abstract

The invention belongs to the field of debris flow disaster prevention and reduction, and provides a channel debris flow blocking protection pile forest which comprises a plurality of protection pile sets, each protection pile set comprises a plurality of protection piles, and each protection pile is arranged in a channel comprising a three-level ramp. The protection pile is composed of a pile pier and an inclined baffle. The bottom surface of the pile pier of each protective pile is fixed in the second-stage ramp; the pile piers of all the protective piles in each protective pile group are located on the same straight line, and the connecting lines of the pile piers of all the protective piles in each protective pile group are parallel to one another and are perpendicular to the channel edge direction of the second-stage channel; the inclined baffles of all the protective piles in the same protective pile group are arranged in the same plane; in the guard pile group closest to the first-stage ramp, the inclined baffle of each guard pile points to the upstream direction of the second-stage ramp, and the inclined baffles of the guard piles in the other guard pile groups point to the downstream direction of the second-stage ramp; the protection piles in the adjacent protection pile sets are arranged in a staggered mode. The energy dissipation effect of an existing pile forest on the channel debris flow can be improved.

Description

Technical Field

[0001] The invention belongs to the field of debris flow disaster prevention and reduction, and relates to a channel debris flow blocking and protection pile forest. Background Art

[0002] Debris flow refers to the flow of rock debris that is caused by loose slopes becoming unstable due to dynamic factors such as heavy rains and earthquakes, and then sliding rapidly along the slope under the action of gravity, and further breaking during movement. Compared with overall landslides and mudslides, debris flows are characterized by the movement of dispersed granular media and the influence of liquid phase on their movement characteristics is minimal. In recent years, the frequency and scale of debris flows have increased significantly due to climate change and human activities. Because debris flows have the characteristics of large amounts of sand, long transport distances, and fast movement speeds, they often bring devastating disasters once they occur.

[0003] Since debris flow is extremely destructive, the research on the transport mechanism and prevention and control methods of debris flow has always been a hot and difficult issue in the field of disaster prevention and mitigation at home and abroad. For example, Kesseler et al. compared the debris flow motion simulation data obtained based on the discrete element method with the results of indoor model tests, and discussed the influence of particle size changes on particle motion results. Zhang Bei conducted a quantitative analysis of the interaction force between debris flow and retaining structure, revealing the influence of particle movement speed, debris flow volume, etc. on the impact force component. Wang Guizhou et al. conducted a series of physical model tests to study the influence of horizontal sliding section width on debris flow movement and accumulation law, and combined with numerical simulation to conduct in-depth discussion on its causal mechanism. Although many scholars at home and abroad have done a lot of research on debris flow disasters, due to the complexity of debris flow problems, there is currently no mature solution for direct engineering use, and the mechanism of action between debris flow and prevention and control structure system is still in the exploration stage.

[0004] Most traditional retaining structures use bulky integral retaining dams. Although integral retaining dams can effectively block debris flows, the sediment accumulated in the integral retaining dams is difficult to clean, which will significantly reduce their disaster prevention and mitigation capabilities. When their limited storage capacity is filled, they lose their ability to resist. Compared with traditional retaining structures, pile forests have the advantages of strong permeability, good stability, and simple structure, and have greater advantages in the prevention and control of debris flow disasters. However, when the debris flow collides with the front edge of the pile forest, a large number of particles will splash upward, causing the energy dissipation efficiency of the pile forest to be significantly reduced. Therefore, it is necessary to improve the existing debris flow retaining and protection pile forests to improve their energy dissipation effect and improve their disaster prevention and mitigation effects. Summary of the invention

[0005] In view of the problem in the prior art of using pile forests to block channel debris flow, that after the debris flow collides with the front edge of the pile forest, a large amount of particles will be splashed upward, thereby significantly reducing the energy dissipation efficiency of the pile forest, the present invention provides a channel debris flow blocking and protection pile forest based on the movement characteristics of the channel debris flow, so as to improve the energy dissipation effect of the existing pile forest on the channel debris flow, and provide a new technical means for the prevention and mitigation of channel debris flow.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0007] A channel debris flow interception protection pile forest, the interception protection pile forest includes at least two protection pile groups, each protection pile group includes a plurality of protection piles, each protection pile is arranged in a channel including a three-level ramp, the three-level ramp includes a first-level ramp, a second-level ramp and a third-level ramp connected to each other, the slopes of the first-level ramp, the second-level ramp and the third-level ramp decrease in sequence, and there is a loose accumulation body in the first-level ramp;

[0008] The protective pile is composed of a pile pier and an inclined baffle, the pile pier is a rectangular parallelepiped, the starting end of the inclined baffle is connected to the top of one side of the pile pier, the terminal end of the inclined baffle is higher than the top surface of the pile pier, and the angle between the inclined baffle and the top surface of the pile pier is 30° to 60°;

[0009] The bottom surface of the pier of each protective pile is fixed in the second-level ramp; the center of the bottom surface of the pier of each protective pile in each protective pile group is located on the same straight line, and the connecting line of the bottom surface centers of the piers of all protective piles in each protective pile group is parallel to each other and perpendicular to the along-course direction of the second-level channel; the inclined baffles of all protective piles in the same protective pile group are arranged in the same plane; in a group of protective piles closest to the first-level ramp, the inclined baffles of each protective pile point to the upstream direction of the second-level ramp, and the inclined baffles of each protective pile in other protective pile groups point to the downstream direction of the second-level ramp; the protective piles in adjacent protective pile groups are arranged in a staggered manner.

[0010] In the above-mentioned technical solution of the protection pile forest for blocking channel debris flow, the distance between adjacent protection piles in each protection pile group is preferably 10% to 20% of the width of the second ramp.

[0011] In the above-mentioned technical solution of the trench debris flow blocking protection pile forest, the distance between the connecting lines of the centers of the bottom surfaces of the piers of each protection pile in adjacent protection pile groups is preferably 50% to 70% of the width of the second ramp.

[0012] In the above-mentioned technical solution of the channel debris flow blocking protection pile forest, the pile piers of the protection piles are arranged perpendicular to the slope surface of the second-level ramp.

[0013] In the above-mentioned technical solution of the channel debris flow blocking protection pile forest, the height of the protection pile is preferably 10% to 20% of the width of the second ramp.

[0014] In the above-mentioned technical solution of the channel debris flow blocking protection pile forest, the height of the pile pier is preferably 50% to 70% of the height of the protection pile.

[0015] In the above-mentioned technical solution of the trench debris flow blocking protection pile forest, the width of the pile pier in the direction of the center line connecting the bottom surfaces of the protection piles of the same protection pile group is preferably 10% to 15% of the width of the second-level trench.

[0016] In the above-mentioned technical solution of the trench debris flow blocking protection pile forest, on the basis of meeting the aforementioned requirements for the width and height of the pile pier, the length of the pile pier in the direction along the second-level ramp (i.e., the thickness of the pile pier) usually only needs to meet the strength of the protection pile to withstand the impact of the debris flow in the trench body, and there are no other special requirements. Preferably, the pile pier is a rectangular parallelepiped with a square bottom surface.

[0017] In the above-mentioned technical solution of the channel debris flow blocking protection pile forest, the width of the inclined baffle in the direction of the center line connecting the bottom surfaces of the piers of each protection pile in the same protection pile group is equal to the width of the pier in the direction of the center line connecting the bottom surfaces of the piers of each protection pile in the same protection pile group.

[0018] In the above-mentioned technical solution of the channel debris flow blocking and protection pile forest, the shape of the inclined baffle is preferably rectangular.

[0019] In the above-mentioned technical solution of the channel debris flow blocking and protection pile forest, on the basis of meeting the aforementioned requirements for the width of the inclined baffle and the angle between the inclined baffle and the top surface of the pile pier, the thickness of the inclined baffle only needs to meet the strength of the inclined baffle to withstand the impact of the debris flow in the channel body, and there are no other special requirements.

[0020] In the above-mentioned technical solution of the channel debris flow blocking and protection pile forest, the number of groups of the blocking and protection pile forest is determined according to actual application, and usually the blocking and protection pile forest includes 2 to 4 protection pile groups.

[0021] In the above-mentioned technical solution of the channel debris flow blocking protection pile forest, the area where the third-level ramp is located or the downstream area of ​​the third-level ramp has disaster prevention and protection objects. Through the blocking and energy dissipation function of the protection pile forest, the disaster prevention and protection objects can have a disaster prevention and mitigation effect.

[0022] Compared with the prior art, the technical solution provided by the present invention produces the following beneficial technical effects:

[0023] 1. The present invention provides a forest of protective piles for blocking channel debris flow, including at least two protective pile groups, each protective pile group including a plurality of protective piles, each protective pile arranged in the channel downstream of the loose accumulation body, and the protective piles in adjacent protective pile groups are arranged in a staggered manner; the protective piles are composed of pile piers and inclined baffles, the pile piers are rectangular, the starting end of the inclined baffle is connected to the top of one side of the pile pier, and the terminal end of the inclined baffle is higher than the top surface of the pile pier. By controlling the arrangement position of the protective piles and the orientation of the inclined baffles and improving the pile pier structure, the forest of protective piles for blocking the channel debris flow of the present invention has a better energy dissipation effect than the existing pile forests, and enhances the disaster prevention and mitigation effect of the existing pile forests on the channel debris flow.

[0024] 2. The present invention has verified through numerical simulation calculation that, compared with ordinary protective piles without inclined baffles, the protective piles composed of a pile pier and an inclined baffle as described in the present invention can effectively reduce the collision between particles of the debris flow on the channel slope and reduce the movement speed of the particles in the channel under the premise of maintaining the total height of the protective piles unchanged, thereby enhancing the energy dissipation effect on the debris flow.

[0025] 3. The channel debris flow blocking protection pile forest of the present invention has the functions of energy dissipation and blocking at the same time, and has a simple structure and good adjustability. In practical applications, the height of the protection piles, the number of protection pile groups, the spacing of the protection piles, and the length and angle of the inclined baffles can be flexibly adjusted according to the project site conditions and specific protection needs, thereby achieving a variety of sand regulation and disaster reduction effects, greatly enhancing the convenience and feasibility of engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a comparison chart of the numerical simulation results of the sediment transport process under different sediment inflow conditions using the discrete element method and the experimental data in the literature.

[0027] Figure 2 It is a schematic diagram of the physical model of the channel consisting of three-level ramps.

[0028] Figure 3 It is a schematic diagram of arranging a forest of channel debris flow interception and protection piles in a channel physical model.

[0029] Figure 4 It is a schematic diagram of the structure of the protective pile.

[0030] Figure 5 It is a side view of the protective pile.

[0031] Figure 6 It is a schematic diagram (top view) of the arrangement of the protection piles on the second-level ramp in Example 1.

[0032] Figures 2 to 6In the figure, 1 is the protection pile, 1-1 is the pier, 1-2 is the inclined baffle, 2 is the first ramp, 3 is the second ramp, 4 is the third ramp, V is the width of the first ramp, L1 is the length of the first ramp, L2 is the length of the second ramp, L3 is the length of the third ramp, α1 is the angle between the slope of the first ramp and the horizontal plane, α2 is the angle between the slope of the second ramp and the horizontal plane, α3 is the angle between the slope of the third ramp and the horizontal plane, a is the edge length of the pier, b is the length of the inclined baffle, H0 is the height of the protection pile, θ is the angle between the inclined baffle and the top surface of the pier, Ly is the distance between adjacent protection piles in the same protection pile group, and Lx is the distance between the lines connecting the centers of the bottom surfaces of the piers of each protection pile in adjacent protection pile groups.

[0033] Figure 7 is the particle size distribution diagram of channel debris flow.

[0034] Figure 8 It is a cloud diagram of the movement speed of particles at different times in the channel physical model using the arrangement described in Comparative Example 1.

[0035] Fig. 9 It is a cloud diagram of the movement speed of particles at different times in the channel physical model using the arrangement described in Comparative Example 2.

[0036] Fig.10 It is a cloud diagram of the movement speed of particles at different times in the channel physical model using the first arrangement form in Example 1.

[0037] Fig.11 These are the numerical simulation results of the effects of the arrangements described in Examples 1 to 5 on the movement speed of particles in the x and z directions. In the figure, no pile forest, ordinary pile forest, new pile forest (30°), new pile forest (45°) and new pile forest (60°) represent the arrangements of Examples 1 to 5, respectively.

[0038] Fig.12 These are the numerical simulation results of the effects of the arrangements described in Examples 1 to 2 and the first, fourth and fifth arrangements in Example 1 on the movement speeds of particles in the x and z directions. In the figure, no pile forest, ordinary pile forest, new pile forest (30°), new pile forest (45°) and new pile forest (60°) represent the arrangement of Example 1, the arrangement of Example 2, and the first, fourth and fifth arrangements in Example 1, respectively.

[0039] Fig.13Figure (A) shows the relationship between the number of unit contacts and time under the layout forms of Comparative Examples 2 to 5. In the figure, the ordinary pile forest, the new pile forest (30°), the new pile forest (45°) and the new pile forest (60°) represent the layout forms of Comparative Examples 2 to 5 respectively. Figure (B) of 13 shows the relationship between the number of unit contacts and time under the layout form of Comparative Example 2 and the first, fourth and fifth layout forms in Example 1. The ordinary pile forest, the new pile forest (30°), the new pile forest (45°) and the new pile forest (60°) represent the layout form of Comparative Example 2 and the first, fourth and fifth layout forms in Example 1 respectively.

[0040] Fig.14 Figure (A) shows the change of the average combined velocity of particles over time under the arrangement of comparative examples 1 to 5. In the figure, no pile forest, ordinary pile forest, new pile forest (30°), new pile forest (45°) and new pile forest (60°) represent the arrangement of comparative examples 1 to 5 respectively. Fig.14 Figure (B) shows the change of the average combined velocity of particles over time in the arrangements of comparative examples 1 to 2 and the first, fourth and fifth arrangements in Example 1. In the figure, no pile forest, ordinary pile forest, new pile forest (30°), new pile forest (45°) and new pile forest (60°) represent the arrangement of comparative example 1, the arrangement of comparative example 2, and the first, fourth and fifth arrangements in Example 1, respectively.

[0041] Fig.15 Figure (A) shows the relationship between the cumulative mass of particles entering the accumulation area (third slope) and time under the layout of comparative examples 1 to 5. In the figure, no pile forest, ordinary pile forest, new pile forest (30°), new pile forest (45°) and new pile forest (60°) represent the layout of comparative examples 1 to 5 respectively. Fig.15 Figure (B) shows the relationship between the cumulative mass of particles entering the stacking area (third slope) under the arrangements of comparative examples 1 to 2 and the first, fourth and fifth arrangements in Example 1. In the figure, no pile forest, ordinary pile forest, new pile forest (30°), new pile forest (45°) and new pile forest (60°) represent the arrangements of comparative examples 1 to 2 and the first, fourth and fifth arrangements in Example 1, respectively. DETAILED DESCRIPTION

[0042] The channel debris flow blocking protection pile forest of the present invention is further described below by using examples in combination with the accompanying drawings. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. The technical personnel in the relevant field make some non-essential improvements and adjustments to the present invention according to the above invention content for specific implementation, which still falls within the scope of protection of the invention.

[0043] In the following embodiments, in order to analyze the influence of the channel debris flow blocking and protection pile forest on the channel debris flow transport process, it is necessary to use the discrete element method to numerically simulate the channel debris flow transport process under different working conditions. Therefore, it is necessary to verify the reliability and accuracy of the discrete element method in simulating the channel debris flow transport process.

[0044] Specifically, it is based on the verification method provided in the literature [Cheng Hao, Han Peifeng, Su Youwen. Analysis of sliding accumulation characteristics and influencing factors of loose bodies based on discrete element method [J]. Acta Physica Sinica, 2020, 69(16): 164501.], and the sediment loads in the literature [Zhou JW, Yang XG, Hou TX. An analysis of the supply process of loose materials to mountainous rivers and gullies as a result of dry debris avalanches [J]. Environmental Earth Sciences, 2017, 76(13): 452.] are 0.005m 3 and 0.015m 3 The numerical calculation was carried out based on the model test, that is, the discrete element method was used to calculate the sediment flow rate of 0.005m 3 and 0.015m 3 The transport process of sediment particles with a particle size of 20 to 60 mm was numerically simulated under the conditions of . The comparison between the numerical simulation results and the experimental data in the literature is shown in Figure 1 As shown by Figure 1 It can be seen that the curve of the relationship between the cumulative mass of particles and time obtained by numerical simulation is consistent with the experimental results as a whole, and the two results are consistent, indicating that it is feasible to simulate the transport process of channel debris flow with the help of discrete element method.

[0045] Example 1

[0046] In this embodiment, a variety of different forms of channel debris flow blocking and protection pile forests are provided.

[0047] Considering that most actual channels are in the form of steep slopes and gentle slopes, this embodiment adopts a channel physical model consisting of three levels of slopes according to the topography of an actual natural channel, such as Figure 2As shown, the channel physical model includes a first ramp 2, a second ramp 3 and a third ramp 4 which are connected to each other. In the channel physical model, the widths of the second and third ramps are equal to the width of the first ramp, the width of the first ramp is V=20m, the length of the first ramp is L1=60m, the length of the second ramp is L2=60m, the length of the third ramp is L3=200m, the angle between the slope surface of the first ramp and the horizontal plane is α1=50°, the angle between the slope surface of the second ramp and the horizontal plane is α2=20°, the angle between the slope surface of the third ramp and the horizontal plane is α3=0°, and there is loose accumulation at the top of the slope surface of the first ramp, which will be transformed into channel debris flow under the impact of the incoming flow.

[0048] The channel debris flow interception and protection pile forest is arranged in the second level ramp of the channel physical model, such as Figure 3 As shown, the specific layout of the channel debris flow blocking and protection pile forest is described below:

[0049] The first arrangement form: a channel debris flow blocking protection pile forest, which includes two protection pile groups, namely a first protection pile group and a second protection pile group. The first protection pile group consists of four protection piles 1, and the second protection pile group consists of three protection piles 1. The first protection pile group is located upstream of the second protection pile group.

[0050] All the protection piles 1 in the first protection pile group and the second protection pile group have the same structure. The structural diagram of the protection piles is as follows: Figure 4 The side view of the protection pile is shown in Figure 5 As shown, the protective pile 1 is composed of a pile pier 1-1 and an inclined baffle 1-2. The pile pier 1-1 is a cube, and the inclined baffle 1-2 is a rectangular plate. The starting end of the inclined baffle 1-2 is connected to the top of one side of the pile pier 1-2, and the terminal end of the inclined baffle 1-2 is higher than the top surface of the pile pier 1-1; the width of the inclined baffle 1-2 (i.e. the width of the starting end of the inclined baffle) is equal to the edge length of the pile pier 1-1; the height of the pile pier 1-1 is 2 / 3 of the height of the protective pile 1. The edge length of the pile pier is denoted as a, the length of the inclined baffle is denoted as b, the angle between the inclined baffle and the top surface of the pile pier is denoted as θ, and the height of the protective pile is denoted as H0. The specific values ​​are: a=2m, b=2m, H0=3m, θ=30°.

[0051] The bottom surface of the pile pier 1-1 of each protection pile 1 is fixed in the second-level ramp, and the pile pier 1-1 of the protection pile 1 is perpendicular to the slope surface of the second-level ramp. The layout diagram (top view) of each protection pile on the second-level ramp is as shown in FIG. Figure 6As shown. The centers of the bottom surfaces of the piers 1-1 of the four protection piles 1 of the first protection pile group are located on the same straight line, the inclined baffles 1-2 of the four protection piles 1 are all set to point to the upstream of the second-level ramp, and the inclined baffles 1-2 of the four protection piles 1 are located on the same plane; the centers of the bottom surfaces of the piers 1-1 of the three protection piles 1 of the second protection pile group are located on the same straight line, the inclined baffles 1-2 of the three protection piles 1 are all set to point to the downstream direction of the second-level ramp, and the inclined baffles 1-2 of the three protection piles 1 are located on the same plane; in the first protection pile group, the distance between adjacent protection piles 1 is Ly=3m, and in the second protection pile group, the distance between adjacent protection piles 1 is Ly=3m. The connecting line of the bottom centers of the piers of each protection pile in the first protection pile group and the connecting line of the bottom centers of the piers of each protection pile in the second protection pile group are parallel to each other and perpendicular to the along-course direction of the second-level ramp. The distance Lx between the connecting line of the bottom centers of the piers of each protection pile in the first protection pile group and the connecting line of the bottom centers of the piers of each protection pile in the second protection pile group is 12m. The protection piles 1 in the first protection pile group are arranged alternately with the protection piles 1 in the second protection pile group. Specifically, the protection piles 1 in the second protection pile group are located on the median perpendicular line of two adjacent protection piles 1 in the first protection pile group.

[0052] The second arrangement form: The second arrangement form is basically the same as the first arrangement form, and the only difference is that the geometric dimension information of each protection pile in the first protection pile group and the second protection pile group is as follows: a=2m, b=1.414m, H0=3m, θ=45°.

[0053] The third arrangement form: The third arrangement form is basically the same as the first arrangement form, and the only difference is that the geometric dimension information of each protection pile in the first protection pile group and the second protection pile group is as follows: a=2m, b=1.155m, H0=3m, θ=60°.

[0054] The fourth arrangement form: The fourth arrangement form is basically the same as the first arrangement form, the only difference is that the geometric dimension information of each protection pile in the first protection pile group is a=2m, b=2m, H0=3m, θ=30°; the geometric dimension information of each protection pile in the second protection pile group is: a=2m, b=1.414m, H0=3m, θ=45°.

[0055] The fifth arrangement form: The fifth arrangement form is basically the same as the first arrangement form, the only difference is that the geometric dimension information of each protection pile in the first protection pile group is a=2m, b=2m, H0=3m, θ=30°; the geometric dimension information of each protection pile in the second protection pile group is: a=2m, b=1.155m, H0=3m, θ=60°.

[0056] Comparative Example 1

[0057] In this comparative example, the channel physical model used is the same as that of Example 1, but no protective stake forest is arranged in the channel. This arrangement form of this comparative example is recorded as no stake forest.

[0058] Comparative Example 2

[0059] In this comparative example, the channel physical model used is the same as that of Example 1, but ordinary protective piles are arranged in the channel physical model. Specifically, the protective piles in the first arrangement form of Example 1 are replaced with ordinary protective piles. The ordinary protective piles are rectangular parallelepipeds with a square bottom surface, a bottom side length of 2m, and a height of 3m. The square bottom surface of the ordinary protective pile is fixed in the second-level ramp, and the ordinary protective pile is perpendicular to the slope surface of the second-level ramp. This arrangement form of this comparative example is recorded as an ordinary pile forest.

[0060] Comparative Example 3

[0061] In this comparative example, the channel physical model adopted is the same as that of Example 1, and the arrangement of the protection piles is basically the same as the first arrangement of Example 1. The only difference is that the protection piles of the second protection pile group in the first arrangement of Example 1 are replaced by ordinary protection piles, and the structure and size of the ordinary protection piles are the same as those of the ordinary protection piles in the comparative example.

[0062] Comparative Example 4

[0063] In this comparative example, the channel physical model adopted is the same as that of Example 1, and the arrangement of the protection piles is basically the same as the second arrangement of Example 1. The only difference is that: each protection pile of the second protection pile group in the second arrangement of Example 1 is replaced by an ordinary protection pile, and the structure and size of the ordinary protection pile are the same as the ordinary protection pile in the comparative example.

[0064] Comparative Example 5

[0065] In this comparative example, the channel physical model adopted is the same as that of Example 1, and the arrangement of the protection piles is basically the same as the third arrangement of Example 1. The only difference is that the protection piles of the second protection pile group in the third arrangement of Example 1 are replaced by ordinary protection piles, and the structure and size of the ordinary protection piles are the same as those of the ordinary protection piles in the comparative example.

[0066] Example 2

[0067] In this embodiment, the discrete element method is used to simulate the transport process of the channel debris flow, specifically simulating the transport process of the channel debris flow in Example 1 and Comparative Examples 1 to 5, to examine the influence of the protective pile forest on the movement law of the channel debris flow.

[0068] This embodiment refers to the method in the literature [Zhao Chuan, Fu Chenghua, Zou Haiming, et al. Numerical simulation analysis of three-dimensional landslide process based on discrete element method [J]. People's Pearl River, 2015, 4 (2): 11-15.] to perform numerical simulation calculations. The calculation parameters used in the numerical simulation are shown in Table 1. The influence of the cohesion between particles is ignored during the numerical simulation calculation process. The particle size distribution of the channel debris flow is shown in Figure 7 shown.

[0069] Table 1 Numerical simulation calculation related parameters

[0070]

[0071] 1. Numerical simulations were performed on the channel physical model using the first arrangement in Example 1 and the channel physical model using the arrangement described in Comparative Example 1 and Comparative Example 2 to compare their effects on the movement law of channel debris flow.

[0072] The aforementioned method of this embodiment is used to perform numerical simulation on the channel physical model using the first arrangement form in Example 1, and the channel physical model using the arrangements described in Comparative Examples 1 and 2. Figure 8 It is a cloud diagram of the movement speed of particles at different times in the channel physical model using the arrangement described in Comparative Example 1. Fig. 9 It is a cloud diagram of the movement speed of particles at different times in the channel physical model using the arrangement described in Comparative Example 2. Fig.10 It is a cloud diagram of the movement speed of particles at different times in the channel physical model using the first arrangement form in Example 1.

[0073] Depend on Figure 8 It can be seen that when no protective piles are arranged in the channel, the debris flow accelerates down the slope under the action of gravity, and the movement speed of the particles continues to increase, showing the characteristics of high kinetic energy and strong impact. Fig. 9 It can be seen that after the ordinary pile forest is arranged in the channel, the ordinary pile forest has a significant blocking effect on the debris flow. When the particles collide with the protective piles in the ordinary pile forest, a large number of particles splash upward, and the particle movement speed is significantly reduced. As a large number of particles splash from the bed surface, the energy dissipation efficiency of the ordinary pile forest decreases. Fig.10 It can be seen that when the protective pile forest of the first arrangement form of Example 1 is used in the channel, the energy dissipation effect of splashed particles can be effectively improved compared with the ordinary pile forest of Comparative Example 2. Figures 9-10 It can be seen that at the 6.6s of the numerical simulation, when the protective pile forest of the first arrangement form of Example 1 is arranged in the channel, the range of the low-speed zone in the channel is larger than that of the ordinary pile forest arranged in the channel in Comparative Example 2. This shows that when the height of the protective pile remains unchanged, the protective pile forest of the present invention arranged in the channel has a higher energy dissipation efficiency than the ordinary pile forest.

[0074] 2. Numerical simulations were performed on the channel physical models using the arrangements described in Comparative Examples 1 to 5, and on the channel physical models using the first, fourth and fifth arrangements in Example 1, to compare their effects on the average particle movement speed.

[0075] The aforementioned method of this embodiment is used to perform numerical simulation on the channel physical model using the arrangement forms described in Comparative Examples 1 to 5. Fig.11 Figure (A) is a numerical simulation result of the effect of the arrangement described in Examples 1 to 5 on the movement speed of particles in the x direction. Fig.11 Figure (B) is a numerical simulation result of the effect of the arrangement described in Examples 1 to 5 on the movement speed of particles in the z direction. Fig.11 Among them, no pile forest, ordinary pile forest, new type pile forest (30°), new type pile forest (45°) and new type pile forest (60°) represent the layout forms of comparative examples 1 to 5 respectively.

[0076] The aforementioned method of this embodiment is used to perform numerical simulation on the channel physical models using the arrangement forms described in Comparative Examples 1 to 2, and the channel physical models using the first, fourth and fifth arrangement forms in Embodiment 1. Fig.12 Figure (A) is a numerical simulation result of the influence of the arrangement forms described in Examples 1 to 2, the first, fourth and fifth arrangement forms in Example 1 on the movement speed of particles in the x direction, Fig.12 Figure (B) is a numerical simulation result of the effect of the arrangement forms described in Examples 1 to 2 and the first, fourth and fifth arrangement forms in Example 1 on the movement speed of particles in the z direction. Fig.12 In the figure, the non-pile forest, the ordinary pile forest, the new pile forest (30°), the new pile forest (45°) and the new pile forest (60°) respectively represent the layout of comparative example 1, the layout of comparative example 2, and the first, fourth and fifth layouts in Example 1.

[0077] Depend on Figures 11-12 It can be seen that, overall, the average speed of the particles in the x and z directions shows a trend of increasing first and then decreasing. Compared with the arrangement of the non-pile forest in comparative example 1, the arrangement of comparative examples 2 to 5 significantly reduces the movement speed of the particles; compared with the ordinary pile forest arrangement in comparative example 2, the arrangement of comparative examples 3 to 5 further reduces the movement speed of the particles. Fig.11. Compared with the arrangement of the non-pile forest in comparative example 1, the first, fourth and fifth arrangements of embodiment 1 significantly reduce the movement speed of the particles; compared with the arrangement of the ordinary pile forest in comparative example 2, the first, fourth and fifth arrangements of embodiment 1 more significantly reduce the movement speed of the particles; and the first, fourth and fifth arrangements of embodiment 1 reduce the movement speed of the particles to a greater extent than the arrangements of comparative examples 3 to 5, see Fig.12 This shows that, compared with the arrangement form in which each of the protection piles in the first protection pile group is a pile pier with an inclined baffle plate, and each of the protection piles in the second protection pile group is an ordinary protection pile, the arrangement form in which each of the protection piles in the first protection pile group and the second protection pile group adopted by the present invention is a pile pier with an inclined baffle plate can more effectively reduce the movement speed of particles and produce a better blocking effect.

[0078] 3. Numerical simulations were performed on the channel physical models using the arrangements described in Comparative Examples 1 to 5, and on the channel physical models using the first, fourth and fifth arrangements in Example 1, to compare their effects on the degree of collision during the movement of debris flow.

[0079] The number of unit contacts in the debris flow movement in the channel can reflect the degree of collision of particles in the channel. The above method of this embodiment is used to numerically simulate the channel physical model using the arrangement form described in comparative examples 1 to 5. The relationship between the change of the number of unit contacts over time in the arrangement form of comparative examples 2 to 5 is as follows: Fig.13 As shown in Figure (A), the variation of the average combined velocity of particles with time in the arrangement forms of Comparative Examples 1 to 5 is as follows Fig.14 As shown in Figure (A), Figures 13-14 In Figure (A), no pile forest, ordinary pile forest, new type pile forest (30°), new type pile forest (45°) and new type pile forest (60°) represent the layout forms of comparative examples 1 to 5 respectively.

[0080] The above method of this embodiment is used to perform numerical simulation on the channel physical model using the arrangement forms described in Comparative Examples 1 to 2, and the channel physical model using the first, fourth and fifth arrangement forms in Example 1. The relationship between the number of unit contacts and time under the arrangement form of Comparative Example 2 and the first, fourth and fifth arrangement forms in Example 1 is as follows: Fig.13 As shown in FIG. (B), the variation of the average combined velocity of particles with time in the arrangement forms of Comparative Examples 1 to 2 and the first, fourth and fifth arrangement forms in Example 1 is as follows Fig.14 As shown in Figure (B), Figures 13-14In Figure (B), the non-pile forest, the ordinary pile forest, the new pile forest (30°), the new pile forest (45°) and the new pile forest (60°) respectively represent the layout of Comparative Example 1, the layout of Comparative Example 2, and the first, fourth and fifth layouts in Example 1.

[0081] Depend on Fig.13 It can be seen that at the beginning of the channel debris flow movement, the slope is relatively dense, and the number of unit contacts at this time is about 31,000. Then, with the rapid movement of the channel debris flow, the number of unit contacts of the particles decreases rapidly, and the number of unit contacts reaches the minimum value after about 7 seconds. Subsequently, the channel debris flow gradually enters the gentle slope section, and the number of unit contacts increases accordingly. Compared with the layout of the ordinary pile forest in Comparative Example 2, the layouts of Comparative Examples 3 to 5 and the first, fourth and fifth layouts of Example 1 can increase the number of unit contacts of the debris flow.

[0082] Combination Figures 13-14 It can be seen that the average combined velocity of particles in the channel shows an opposite trend to the change in the number of unit contacts. The increase in the number of unit contacts in the channel debris flow means that the number of friction collisions between particles increases, thereby increasing the energy loss of the debris flow and the average combined velocity of the particles decreases accordingly. Fig.14 It can be seen that if the average combined velocity of particles in the ordinary pile forest arrangement form of comparative example 2 is used as a reference for comparison, the degree of reduction in the average combined velocity of particles in the first, fourth and fifth arrangements of Example 1 is greater than the degree of reduction in the average combined velocity of particles in the arrangements in comparative examples 3 to 5. This also shows that, compared with the arrangement form in which each of the protective piles in the first protective pile group is a pile pier with an inclined baffle plate, and each of the protective piles in the second protective pile group is an ordinary protective pile, the arrangement form in which each of the protective piles in the first protective pile group and the second protective pile group adopted by the present invention is a pile pier with an inclined baffle plate can effectively increase the friction and collision between particles, thereby effectively reducing the movement speed of the particles.

[0083] 4. Numerical simulations were performed on the channel physical models using the layouts described in Comparative Examples 1 to 5, and on the channel physical models using the first, fourth and fifth layouts in Example 1, to compare their effects on the downstream sediment replenishment process.

[0084] The above method of this embodiment is used to perform numerical simulation on the channel physical model using the arrangement forms described in Comparative Examples 1 to 5. The relationship between the cumulative mass of particles entering the accumulation area (third level slope) and time under the arrangement forms of Comparative Examples 1 to 5 is as follows: Fig.15 As shown in Figure (A), Fig.15 In the figure (A), no pile forest, ordinary pile forest, new type pile forest (30°), new type pile forest (45°) and new type pile forest (60°) represent the layout forms of comparative examples 1 to 5 respectively.

[0085] The above method of this embodiment is used to perform numerical simulation on the channel physical model using the arrangement forms described in Comparative Examples 1 to 2, and the channel physical model using the first, fourth and fifth arrangement forms in Example 1. The relationship between the cumulative mass of particles entering the accumulation area (third-level slope) and the time under the arrangement forms of Comparative Examples 1 to 2 and the first, fourth and fifth arrangement forms in Example 1 is as follows: Fig.15 As shown in Figure (B), Fig.15 In the figure (B), the non-pile forest, the ordinary pile forest, the new pile forest (30°), the new pile forest (45°) and the new pile forest (60°) respectively represent the layout forms of comparative examples 1 to 2, and the first, fourth and fifth layout forms in Example 1.

[0086] Depend on Fig.15 It can be seen that: as time goes by, the rate of increase of the mass of sediment entering the accumulation area shows a trend of first increasing and then decreasing; relative to the arrangement of the non-pile forest in comparative document 1, the arrangement of the retaining structure in the channel will cause the starting time of particles entering the downstream to be delayed and significantly reduce the mass of sediment replenishment; relative to the ordinary pile forest arrangement in comparative example 2, the arrangements of comparative examples 3 to 5 and the first, fourth and fifth arrangements in embodiment 1 have better sand regulation effects; the fifth arrangement in embodiment 1 shows the best sand regulation effect.

[0087] This embodiment has confirmed through the above numerical simulation process that, compared with the case of using ordinary pile forests, the arrangement of the channel debris flow blocking protection pile forest of the present invention in the channel can effectively reduce the collision between particles of the channel slope debris flow and reduce the movement speed of particles in the channel, while at the same time producing better energy dissipation and regulating the downstream sediment replenishment process, and can produce better disaster prevention and mitigation effects on the channel debris flow.

Claims

1. A channel debris flow blocking and protection pile forest, characterized in that: The barrier protection pile forest comprises at least two protection pile groups, each protection pile group comprises a plurality of protection piles (1), each protection pile is arranged in a channel comprising a three-level ramp, the three-level ramp comprises a first-level ramp (2), a second-level ramp (3) and a third-level ramp (4) connected to each other, the slopes of the first-level ramp, the second-level ramp and the third-level ramp decrease in sequence, and the first-level ramp has a loose accumulation body; The protective pile (1) is composed of a pile pier (1-1) and an inclined baffle (1-2); the pile pier (1-1) is in the form of a rectangular parallelepiped; the starting end of the inclined baffle (1-2) is connected to the top of one side surface of the pile pier (1); the ending end of the inclined baffle (1-2) is higher than the top surface of the pile pier; and the angle between the inclined baffle (1-2) and the top surface of the pile pier (1-1) is 30° to 60°; The bottom surface of the pier (1-1) of each protection pile (1) is fixed in the second-level ramp; the centers of the bottom surfaces of the piers of each protection pile (1) in each protection pile group are located on the same straight line, and the connecting line of the centers of the bottom surfaces of all the protection piles (1) in each protection pile group is parallel to each other and perpendicular to the along-course direction of the second-level channel; the inclined baffles (1-2) of all the protection piles (1) in the same protection pile group are arranged in the same plane; in a group of protection piles closest to the first-level ramp, the inclined baffles (1-1) of each protection pile (1) point to the upstream direction of the second-level ramp, and the inclined baffles (1-1) of each protection pile (1) in other protection pile groups point to the downstream direction of the second-level ramp; the protection piles (1) in adjacent protection pile groups are arranged in a staggered manner.

2. The channel debris flow blocking and protection pile forest according to claim 1 is characterized in that: The distance between adjacent protection piles (1) in each protection pile group is 10% to 20% of the width of the second-level ramp.

3. The channel debris flow blocking and protection pile forest according to claim 1 is characterized in that: The distance between the connecting lines of the bottom centers of the pile piers (1-1) of each protection pile (1) in the adjacent protection pile groups is 50% to 70% of the width of the second ramp.

4. The channel debris flow blocking and protection pile forest according to claim 1 is characterized in that: The pile pier (1-1) of the protection pile (1) is arranged perpendicular to the slope surface of the second-level ramp.

5. The channel debris flow blocking and protection pile forest according to any one of claims 1 to 4, characterized in that: The height of the protection pile (1) is 10% to 20% of the width of the second ramp.

6. The channel debris flow blocking and protection pile forest according to claim 5 is characterized in that: The height of the pile pier (1-1) accounts for 50% to 70% of the height of the protection pile (1).

7. The channel debris flow blocking and protection pile forest according to any one of claims 1 to 4, characterized in that: The width of the pile pier (1-1) in the direction of the center line connecting the bottom surfaces of the pile piers of the same protective pile group is 10% to 15% of the width of the second-level channel.

8. The channel debris flow blocking and protection pile forest according to any one of claims 1 to 4, characterized in that: The width of the inclined baffle (1-2) in the direction of the center line connecting the bottom surfaces of the piers of each protection pile in the same protection pile group is equal to the width of the pier (1-1) in the direction of the center line connecting the bottom surfaces of the piers of each protection pile in the same protection pile group.

9. The channel debris flow blocking and protection pile forest according to any one of claims 1 to 4, characterized in that: The blocking and protection pile forest includes 2 to 4 protection pile groups.

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