Calculation method of debris flow velocity based on critical condition of large particle starting

Abstract

The present application relates to the field of debris flow disaster prevention, in particular to a method for calculating the flow velocity of debris flow based on the starting critical condition of large particles, comprising the following steps: building a flume experimental device and placing large particle materials in the flume experimental device; applying medium flow action to the flume experimental device to form a stable medium flow field inside the flume experimental device; detecting the large particle materials to obtain the motion parameters and structure parameters of the large particle materials; determining the force characteristic parameters in the motion process of the large particle materials according to the motion parameters of the large particle materials; and determining the starting action flow velocity of the large particle materials according to the starting critical condition of the large particles, the force characteristic parameters and the structure parameters. The present application simulates the physical process of debris flow occurrence by building a flume experimental device and discriminates the starting condition of large particles at the sudden contraction of the channel by using the empirical formula of debris flow motion, thereby improving the identification accuracy and reliability of the sudden amplification of debris flow flow caused by the large particle blockage at the sudden contraction of the channel.

Description

Technical Field

[0001] This invention relates to the field of debris flow disaster prevention and control, and in particular to a method for calculating debris flow velocity based on the critical conditions for the initiation of large particles. Background Technology

[0002] Debris flows are geological hazards that can easily cause enormous damage, characterized by their numerous locations, wide distribution, large scale, and severe consequences. In areas of intense tectonic activity, the micro-topography at the abrupt narrowing of debris flow channels is becoming increasingly common, and the phenomenon of large particles blocking debris flow channels is significant. Due to their unique geomorphological features, these abrupt narrowing points of channels easily lead to localized fluid confinement and sediment accumulation, resulting in a blockage effect.

[0003] Large particles at abrupt gully narrowing points can easily clog the gully, increasing the risk of debris flow blockage and collapse, and potentially causing more severe disasters. Large particles in debris flows readily form blockages at gully narrowing points. Since these large particles occupy the majority of the gully cross-section, when the amount of large particles carried by the upstream debris flow significantly increases, the debris flow blocks the gully cross-section and gradually accumulates behind boulders. As the downstream debris flow continues to accumulate, the mud level gradually rises, leading to a continuous increase in pressure on the large particles. While there is a flow attenuation process when the drag force has not reached the critical condition for large particle activation, when the height of the downstream debris flow exceeds the height of the blockage dams on both sides, the debris flow overflows along the flow paths on both sides. The strong erosive force creates gullies, causing the banks to collapse and ultimately breach. When the drag force reaches the critical condition for large particle activation, the large particles and their subsequent deposits participate in the debris flow movement, resulting in a sudden increase in the debris flow rate. Therefore, how to determine the initiation of large particles in response to the phenomenon of large particle blockage at the sudden narrowing of gullies significantly amplifying debris flow is of great significance for improving the predictability and reliability of debris flow disaster identification. Summary of the Invention

[0004] To accurately identify and assess the sudden amplification of debris flow flow caused by large particles clogging and breaching at abrupt channel narrowing in debris flow scenarios, and to improve the reliability of debris flow disaster early warning, this invention provides a method for calculating debris flow velocity based on the critical condition for large particle initiation. The method includes the following steps:

[0005] A water tank experimental device was constructed, and large particles of material were placed in the water tank experimental device.

[0006] A medium flow is applied to the water tank experimental device, thereby forming a stable medium flow field inside the water tank experimental device;

[0007] The large particulate material is tested to obtain its motion parameters and structural parameters.

[0008] Based on the motion parameters of the large particles, determine the force characteristic parameters during the motion of the large particles;

[0009] The initiation velocity of the large particle material is determined based on the critical initiation condition for large particles, the force characteristic parameters, and the structural parameters.

[0010] Preferably, a water tank experimental apparatus is constructed, and large-particle materials are placed in the water tank experimental apparatus, specifically:

[0011] An inclined water tank and flow rate regulating device are set up, and large particles of material are placed on the surface of the water tank; the large particles of material are stones that meet the preset particle size conditions.

[0012] The water tank has a constant width and a constant depth, and the tilt angle of the water tank can be adjusted; the flow rate regulating device can create a simulated medium flow environment in the water tank.

[0013] Preferably, the flow rate regulating device includes a plurality of media output terminals arranged in an array, each media output terminal being equipped with a speed regulating pump and a valve;

[0014] The speed-regulating pump is used to control the flow rate and / or velocity at the medium output end; the valve is used to control whether the medium is output at the medium output end.

[0015] Preferably, a medium flow is applied to the water tank experimental device to form a stable medium flow field inside the water tank experimental device, specifically:

[0016] The flow rate regulating device controls the flow rate and / or velocity of the medium to different areas inside the water tank, while simultaneously collecting real-time information on the medium flow inside the water tank.

[0017] Based on the actual flow of the medium, the output flow rate and / or output velocity of the medium in the flow rate regulating device are changed until a stable medium flow field is formed inside the water tank.

[0018] Preferably, the actual flow of the medium inside the water tank is collected, specifically as follows:

[0019] The flow velocity and / or flow rate of the medium at different locations inside the water tank are collected by a flow velocity sensor installed inside the water tank, which serves as the actual flow status of the medium inside the water tank; wherein, the flow velocity sensor includes at least one of an ultrasonic Doppler flow meter, an electromagnetic flow meter, and a Pitot tube.

[0020] Preferably, based on the actual medium flow conditions, the medium output flow rate and / or medium output velocity of the flow rate regulating device are changed until a stable medium flow field is formed inside the water tank, specifically as follows:

[0021] By comparing the flow velocity and / or flow rate of the medium at different locations inside the water tank, the difference in flow velocity and / or flow rate between any two adjacent locations inside the water tank is obtained.

[0022] Based on the difference in medium flow velocity and / or the difference in medium flow rate, determine whether a stable medium flow field is formed inside the water tank; if yes, keep the medium output flow rate and / or medium output velocity of the flow rate regulating device unchanged; if no, change the medium output flow rate and / or medium output velocity of the flow rate regulating device until a stable medium flow field is formed inside the water tank.

[0023] Preferably, the large particulate material is detected to obtain its motion parameters and structural parameters, specifically as follows:

[0024] A camera is placed near the water tank of the water tank experimental device to capture dynamic images of debris flow inside the water tank; the dynamic images of debris flow are analyzed to obtain the motion parameters and structural parameters of the large particles; wherein, the motion parameters include the trajectory and velocity of the large particles; the structural parameters include the height of the large particles and the critical depth of the debris flow when the large particles cause blockage and collapse.

[0025] Preferably, the force characteristic parameters during the movement of the large particles are determined based on the motion parameters of the large particles, specifically as follows:

[0026] Based on the trajectory and speed of the large particles, the drag force coefficient and friction coefficient during the movement of the large particles are determined and used as characteristic parameters of the force.

[0027] Preferably, the initiation velocity of the large particle material is determined based on the critical initiation condition for large particles, the force characteristic parameters, and the structural parameters, specifically as follows:

[0028] Based on the critical condition for the initiation of large particles, a force balance model for large particle materials is determined; wherein, the critical condition for the initiation of large particles refers to the drag force on the large particle material being equal to the friction force on the large particle material.

[0029] The initiation velocity of the large particle material is determined based on the force balance model, the force characteristic parameters, and the structural parameters.

[0030] Preferably, the initiation velocity of the large particle material is determined based on the force balance model, the force characteristic parameters, and the structural parameters, specifically as follows:

[0031] Substituting the drag force coefficient, the friction coefficient, and the structural parameters into the force balance model, the initiation velocity of the large particle material is obtained; wherein, the initiation velocity refers to the difference between the debris flow velocity and the movement velocity of the large particle material.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides a method for calculating debris flow velocity based on the critical condition for large particle initiation. This method includes constructing a flume experimental device and placing large particles within it; applying a medium flow to the flume to create a stable medium flow field; detecting the large particles to obtain their motion and structural parameters; determining the force characteristic parameters during their movement based on their motion parameters; and determining the initiation velocity of the large particles based on the critical initiation condition, force characteristic parameters, and structural parameters. By simulating the physical process of debris flow occurrence using a flume experimental device and employing empirical formulas for debris flow motion to identify the initiation of large particles at channel constrictions, this method overcomes the technical bottleneck in debris flow disaster prediction and improves the accuracy and reliability of identifying sudden amplification of debris flow flow caused by large particle blockage at channel constrictions. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0035] Figure 1 This is a flowchart of the debris flow velocity calculation method based on the critical condition for large particle initiation provided by the present invention.

[0036] Figure 2 This is a structural diagram of the water tank experimental setup.

[0037] Figure 3 It describes the stress state of large particles. Detailed Implementation

[0038] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining the present invention and not for limiting the present invention. Furthermore, it should be noted that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, not all structures. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0039] The terms "comprising" and "having," and any variations thereof, used in this invention are intended to cover non-exclusive inclusion. For example, a process, method, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0040] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0041] Please see Figure 1 As shown, this invention provides a method for calculating debris flow velocity based on the critical condition for large particle initiation. The method includes the following steps:

[0042] Set up a water tank experimental device and place large particles in the water tank experimental device;

[0043] A medium flow is applied to the water tank experimental device, thereby forming a stable medium flow field inside the water tank experimental device;

[0044] Large particulate materials are tested to obtain their motion and structural parameters.

[0045] Based on the motion parameters of large particles, determine the characteristic parameters of the forces acting on the large particles during their motion.

[0046] The starting velocity of large particles is determined based on the critical starting conditions, force characteristic parameters, and structural parameters.

[0047] Compared to measuring the initiation state of large particles at the site of a debris flow, this method, by constructing a flume experimental device and altering the internal medium flow environment, can reproduce the movement of large particles with the debris flow in a real debris flow scenario to the greatest extent possible. This method can accurately simulate and predict the initiation state of large particles in channels under different geographical conditions, improving the accuracy and reliability of identifying sudden amplification of debris flow caused by blockage of large particles at channel narrowing points.

[0048] Furthermore, a water tank experimental setup was constructed, and large particles of material were placed within the setup, specifically:

[0049] Set up an inclined water tank and flow rate regulating equipment, and place large particles of material on the surface of the water tank; the large particles of material are stones that meet the preset particle size conditions; the stones can be, but are not limited to, gravel or boulders with a particle size greater than or equal to 1m; the abrupt narrowing of the channel in the area where the debris flow occurs refers to the place where the debris flow channel shrinks or narrows sharply at a certain point or within a certain distance, and the above place can be called a bottleneck or narrow channel.

[0050] The water tank has a constant width and a constant depth, and the tilt angle of the water tank can be adjusted; the flow rate adjustment device can create a simulated medium flow environment in the water tank.

[0051] Furthermore, the flow rate regulating device includes several media output terminals arranged in an array, each media output terminal being equipped with a speed regulating pump and a valve;

[0052] Speed-regulating pumps are used to control the flow rate and / or velocity at the medium output end; valves are used to control whether or not the medium is output at the medium output end.

[0053] Please see Figure 2 To simulate and reproduce debris flow scenarios, a flume experimental setup was constructed. This setup simulates debris flow scenarios under different conditions, such as varying slopes and flow velocities / flow rates, meeting the needs for analyzing diverse debris flow behavior. Different types of sensors were also installed on the flume to collect real-time motion and image data of the debris flow process during operation. Each operation of the flume was treated as an independent experiment. Analyzing the motion and image data during each operation helps to accurately identify the dynamic state of debris flow.

[0054] Specifically, an inclined water tank and flow rate regulating device are first set up. Large particles of material are placed on the surface of the water tank. The water tank may include a hollow rectangular transparent tank with openings at both ends, and a slope adjustment mechanism set at the bottom of the tank. The surface of the tank is covered with large particles of material. The slope adjustment mechanism may include, but is not limited to, retractable support frames set at both ends of the bottom of the tank. By changing the extension length of the retractable support frames, the inclination angle of the tank can be changed. For example, the inclination angle of the tank can be adjusted to different angle values ​​such as 7°, 10°, and 13°. The water tank has a constant width and a constant depth to simulate the channel structure of debris flow sliding in a debris flow scenario.

[0055] The flow rate regulating device is used to create a simulated media flow environment inside the tank. By supplying a media solution to a corresponding location within the tank (e.g., the top), the solution flows downwards along the tank's slope, creating a media flow. Large particles placed on the tank surface slide under the influence of this flow, simulating a mudflow. The media solution can be clear water or an aqueous solution containing a small amount of sediment. To ensure the flow rate regulating device provides media flows with varying motion states, it includes several media output terminals arranged in an array. Each output terminal is equipped with a speed-regulating pump and a valve, allowing it to output media solution to a corresponding location within the tank. The speed-regulating pump controls the flow rate and / or velocity at the output terminals; the valve controls whether media is output. By changing the operating states of the pump and valve, the dynamic output of the media solution at each output terminal can be altered, ultimately creating a suitable and controllable media flow environment within the tank.

[0056] Furthermore, a medium flow is applied to the water tank experimental device, thereby forming a stable medium flow field inside the water tank experimental device, specifically as follows:

[0057] The flow rate regulation device controls the flow rate and / or velocity of the medium to different areas inside the water tank, while simultaneously collecting real-time data on the medium flow inside the water tank.

[0058] Based on the actual flow of the medium, change the output flow rate and / or output velocity of the medium from the flow rate regulating device until a stable medium flow field is formed inside the water tank.

[0059] Furthermore, the actual flow of the medium inside the water tank was collected, specifically as follows:

[0060] The flow velocity and / or flow rate of the medium at different locations inside the water tank are collected by a flow velocity sensor installed inside the water tank, which serves as the real-time condition of the medium flow inside the water tank; wherein, the flow velocity sensor includes at least one of ultrasonic Doppler flow meter, electromagnetic flow meter, and Pitot tube.

[0061] Furthermore, based on the actual medium flow conditions, the medium output flow rate and / or medium output velocity of the flow rate regulating device are changed until a stable medium flow field is formed inside the water tank, specifically as follows:

[0062] By comparing the flow velocity and / or flow rate of the medium at different locations inside the water tank, the difference in flow velocity and / or flow rate between any two adjacent locations inside the water tank can be obtained.

[0063] Based on the difference in medium flow velocity and / or the difference in medium flow rate, determine whether a stable medium flow field has been formed inside the water tank; if so, keep the medium output flow rate and / or medium output velocity of the flow rate regulating device unchanged; if not, change the medium output flow rate and / or medium output velocity of the flow rate regulating device until a stable medium flow field is formed inside the water tank.

[0064] Several flow velocity sensors are installed inside the water tank to detect and collect the medium flow velocity and / or flow rate at different locations within the tank, thereby enabling accurate and comprehensive monitoring of the medium flow state during the formation of the medium flow environment within the tank. To meet the different requirements for medium flow detection accuracy inside the tank, the flow velocity sensors include at least one of ultrasonic Doppler flow meters, electromagnetic flow meters, and Pitot tubes, thus providing reliable data for analyzing the medium flow environment inside the tank.

[0065] To simulate a media flow environment within the tank that closely resembles a real debris flow scenario, it is crucial to ensure that the media flow environment inside the tank remains stable and free from abrupt changes. Therefore, the flow velocity and / or flow rate at different locations within the tank are compared. Based on the flow velocity and / or flow rate at all locations within the tank, a global spatial distribution of flow velocity and / or flow rate is generated within the tank. Further analysis of this flow velocity and / or flow rate distribution yields the difference in flow velocity and / or flow rate between any two adjacent locations within the tank. If the difference in the flow velocity of the aforementioned medium is less than the first preset difference and / or the difference in the flow rate of the aforementioned medium is less than the second preset difference, it is determined that a stable medium flow field has been formed inside the water tank. At this time, the output flow rate and / or output velocity of the medium of the flow rate adjustment device are kept constant. If the difference in the flow velocity of the aforementioned medium is greater than or equal to the first preset difference and / or the difference in the flow rate of the aforementioned medium is greater than or equal to the second preset difference, it is determined that a stable medium flow field has not been formed inside the water tank. At this time, the output flow rate and / or output velocity of the medium of the flow rate adjustment device are changed until a stable medium flow field is formed inside the water tank. This provides a basis for conducting multiple repeatable experiments in a stable and controllable debris flow simulation scenario in the water tank experimental device.

[0066] Furthermore, the large particles were analyzed to obtain their motion and structural parameters, specifically:

[0067] A camera was placed near the water tank in the water tank experimental device to capture dynamic images of debris flow inside the water tank. The dynamic images of debris flow were analyzed to obtain the motion parameters and structural parameters of large particles. Among them, the motion parameters include the trajectory and velocity of the large particles; the structural parameters include the height of the large particles and the critical depth of the debris flow when the large particles cause blockage and collapse.

[0068] Considering the complex motion state of the debris flow simulated by the flume experimental device during the experiment, a camera was set up near the flume of the experimental device to capture dynamic images of the debris flow inside the flume in order to accurately identify the entire debris flow process. The dynamic images of the debris flow were analyzed to obtain motion parameters such as the trajectory and velocity of large particles, as well as structural parameters such as the height of large particles and the critical depth of the debris flow when large particles cause blockage and collapse. This provides a reliable and sufficient basis for subsequent determination of the initiation state of large particles using empirical formulas.

[0069] Furthermore, based on the motion parameters of the large particles, the characteristic parameters of the forces acting on the large particles during their motion are determined, specifically:

[0070] Based on the trajectory and speed of the large particles, the drag force coefficient and friction coefficient during the movement of the large particles are determined and used as characteristic parameters of the force.

[0071] Furthermore, based on the critical initiation conditions, force characteristic parameters, and structural parameters of large particles, the initiation flow velocity of large particles is determined, specifically as follows:

[0072] Based on the critical condition for the initiation of large particles, a force balance model for large particle materials is determined; whereby the critical condition for the initiation of large particles refers to the drag force on the large particle material being equal to the friction force on the large particle material.

[0073] Based on the force balance model, force characteristic parameters, and structural parameters, the initiation velocity of large particles is determined.

[0074] Furthermore, based on the force balance model, force characteristic parameters, and structural parameters, the initiation velocity of large particulate materials is determined, specifically as follows:

[0075] Substituting the drag coefficient, friction coefficient, and structural parameters into the force balance model, the initiation velocity of large particles is obtained; where the initiation velocity refers to the difference between the debris flow velocity and the velocity of the large particles.

[0076] Please see Figure 3 The physical model of the motion of large particles during debris flow needs to consider the gravity F acting on the large particles. G buoyancy F LDragging force F D Friction force F μ The combined effect. Among them,

[0077] The gravity F of large particles G =m s g,m s =ρ b B 2 h;

[0078] In the above formula, m s The value represents the mass of the large particles, and g represents the acceleration due to gravity, which is 9.8 m / s². 2 , ρ b B represents the density of the large particles, B represents the length of the large particles in the flow direction, and h represents the height of the large particles.

[0079] The buoyancy force F on large particles L =ρ c gV L V L =B 2 H;

[0080] In the above formula, ρ c V represents the unit weight of a debris flow. L H represents the volume of large particles immersed in the mudflow slurry, and H represents the critical depth of the mudflow when large particles cause blockage and collapse.

[0081] The drag force F on large particles D =ρ c HBC d (u) c -u b ) 2 u i = u c -u b ;

[0082] In the above formula, u c u represents the velocity of the debris flow. b u represents the velocity of large particles. i C represents the initiation velocity of large particulate materials. d This represents the drag coefficient.

[0083] Large particles are affected by buoyancy and debris flow liquefaction, and are also subject to frictional forces; among these, the frictional force F experienced by the large particles is... μ =μ(m s gcosθ-ρ c gV L );

[0084] In the above formula, μ represents the friction coefficient, and θ represents the inclination angle of the tank, that is, the longitudinal slope of the channel inside the tank.

[0085] Multiple experiments were conducted using a water tank experimental setup to obtain the friction coefficient μ and the drag coefficient C. d Based on empirical calculations, the drag coefficient of the friction coefficient μ can take values ​​that are, but are not limited to, 0.7. d The value of can be, but is not limited to, 0.65. Based on the critical condition for the large particle's initiation—that the drag force on the large particle is equal to the frictional force on the large particle—a force balance model for the large particle is determined, and this is combined with the friction coefficient μ and the drag coefficient C. d Based on empirical calculations, the starting flow velocity u of large particles was obtained. i ,

[0086] u i = .

[0087] In practical operation, this invention utilizes two real-world conditions to determine the initiation flow rate u of the aforementioned large particulate materials. i The calculation formula is verified as follows:

[0088] Example 1 corresponds to a gully mouth, located 6.1 km upstream. The main gully is 21.96 km long, with a drainage area of ​​65.55 km². 2 The valley has an average longitudinal slope of 131.9‰, narrow channels, numerous waterfalls and steep shoals, and well-developed gullies, with a maximum relative elevation difference of 3042m. At the point of large-particle blockage, the longitudinal slope of the gully is 13°, and the debris flow unit weight is 1800 kg / m³. 3 The large particles (basalt) in the channel have dimensions of 7.2 m × 6.1 m × 8.5 m, meaning the size B of the large particles in the flow direction is 7.2 m. Historical monitoring data shows that the flow velocity at the blockage point of the large particles is approximately 7.4 m / s. Substituting this data into the initial initiation velocity u of the large particles... i The calculation formula includes the relevant parameters for starting large particle materials, as shown in Table 1 below.

[0089] Table 1

[0090] Longitudinal slope gradient of the gully (°) Dimensions of large particles in the flow direction (m) Channel width (m) <![CDATA[Basalt density (kg / m 3 )]]> <![CDATA[Debris flow density (kg / m 3 )]]> Debris flow velocity (m / s) Starting flow rate (m / s) 13 7.2 8.1 3300 1800 7.4 7.7

[0091] As shown in Table 1 above, the starting velocity of the large particles is 7.7 m / s, while the actual velocity at this cross-section is approximately 7.4 m / s. Therefore, the large particles did not initiate the flow, and the calculated result is consistent with reality.

[0092] Example 2 corresponds to a tributary ditch. Within this ditch is a large rock, measuring 2 m × 1.8 m × 1.2 m, composed of Middle to Late Proterozoic granite. The rock mass is intact, and the vegetation on the lower sections of both banks of the ditch has been completely eroded. According to the on-site investigation, a rock was originally located approximately 150 m upstream and was moved to another location by a debris flow. Meanwhile, the surfaces of other large rocks in the ditch all exhibit obvious moss, proving that the large rocks were not moved by the debris flow. However, the absence of moss on the surface of this particular large rock further confirms that it was carried there by the debris flow.

[0093] The bulk density of the debris flow in the tributary is 1722 kg / m³. 3 The longitudinal slope of the channel at the original location of the large particles is approximately 6.3°, the flow velocity at the debris flow cross-section of the blockage point is approximately 3.20 m / s, and the size of the large particles in the flow direction is 1.8 m. Substituting these data into the initiation velocity u of the large particle material mentioned earlier... i The calculation formula is as follows. The relevant parameters for starting up this large particle material are shown in Table 2 below.

[0094] Table 2

[0095] Longitudinal slope gradient of the gully (°) Dimensions of large particles in the flow direction (m) Channel width (m) <![CDATA[Granite density (kg / m 3 )]]> <![CDATA[Unit weight of debris flow (kg / m 3 )]]> Debris flow velocity (m / s) Starting flow rate (m / s) 6.3 1.8 4.3 2600 1722 3.2 3.0

[0096] As shown in Table 2 above, the initiation velocity of the large particles in this tributary is 3.0 m / s, while the velocity at this cross-section is approximately 3.2 m / s. Therefore, the large particles in this tributary have been initiated, and the calculation results are consistent with reality.

[0097] In one embodiment of the present invention, a computer-readable storage medium is also provided, on which a computer program is stored, the computer program implementing the method described above when executed by a processor.

[0098] In one embodiment of the present invention, the present invention also provides a computer device, the computer device including at least a memory and a processor, wherein a computer program is stored in the memory, and the computer program, when executed by the processor, implements the method described above.

[0099] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of a necessary general-purpose hardware platform, or by a combination of hardware and software. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a computer product. The present invention 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.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Other embodiments may also be used. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the flow velocity of a debris flow based on the critical condition of large particle start-up, characterized in that, The method comprises the following steps: constructing a flume experimental device, and placing large-particle materials in the flume experimental device; applying medium flow action to the flume experimental device, so as to form a stable medium flow field inside the flume experimental device; detecting the large-particle materials to obtain motion parameters and structure parameters of the large-particle materials; wherein the motion parameters comprise a motion trajectory and a motion speed of the large-particle materials; and the structure parameters comprise a height of the large-particle materials and a critical depth of a debris flow when the large-particle materials are blocked and breached; determining an acting force characteristic parameter of the large-particle materials in a motion process according to the motion parameters of the large-particle materials; determining a starting acting flow rate of the large-particle materials according to a large-particle starting critical condition, the acting force characteristic parameter and the structure parameters, specifically as follows: determining a force balance model of the large-particle materials according to the large-particle starting critical condition; wherein the large-particle starting critical condition refers to that a drag force received by the large-particle materials is equal to a friction force received by the large-particle materials; determining the starting acting flow rate of the large-particle materials according to the force balance model, the acting force characteristic parameter and the structure parameters, specifically as follows: substituting the drag force coefficient, the friction coefficient and the structure parameters into the force balance model to obtain the starting acting flow rate of the large-particle materials; wherein the starting acting flow rate refers to a difference between a flow rate of the debris flow and a motion speed of the large-particle materials.

2. The method according to claim 1, wherein the flume experimental device is constructed, and large-particle materials are placed in the flume experimental device, specifically as follows: a water tank arranged in an inclined manner and a flow rate adjusting device are arranged, and the large-particle materials are placed on a tank surface of the water tank; the large-particle materials are stone materials meeting a preset particle size condition; wherein the water tank has a constant width and a constant depth, and an inclination angle of the water tank is adjustable; the flow rate adjusting device can form a simulated medium flow environment in the water tank.

3. The method according to claim 2, wherein the flow rate adjusting device comprises a plurality of medium output ends arranged in an array, and each medium output end is provided with a speed regulating pump and a valve; the speed regulating pump is used to control flow rate and / or flow speed of the medium output end; and the valve is used to control whether the medium output end outputs medium or not.

4. The method according to claim 2, wherein the medium flow action is applied to the flume experimental device, so as to form a stable medium flow field inside the flume experimental device, specifically as follows: flow rate and / or flow speed of medium output by the flow rate adjusting device to different regions inside the water tank are controlled, and medium flow live in the water tank is collected at the same time; flow output rate and / or flow output speed of the flow rate adjusting device are changed according to the medium flow live until the stable medium flow field is formed inside the water tank.

5. The method according to claim 4, wherein the medium flow live in the water tank is collected, specifically as follows: The medium flow rate and / or medium flow volume at different positions inside the flume are collected by a flow rate sensor arranged in the flume, and are used as the medium flow live inside the flume; wherein the flow rate sensor comprises at least one of an ultrasonic Doppler flow meter, an electromagnetic flow meter and a Pitot tube.

6. The method of claim 5, wherein, According to the medium flow live, the medium output flow volume and / or medium output flow rate of the flow rate adjusting device are changed until a stable medium flow field is formed inside the flume, in particular: The medium flow rate difference and / or medium flow volume difference between every two adjacent positions inside the flume are obtained by comparing the medium flow rate and / or medium flow volume at different positions inside the flume; According to the medium flow rate difference and / or medium flow volume difference, it is determined whether a stable medium flow field is formed inside the flume; If yes, the medium output flow volume and / or medium output flow rate of the flow rate adjusting device are kept unchanged; if no, the medium output flow volume and / or medium output flow rate of the flow rate adjusting device are changed until a stable medium flow field is formed inside the flume.

7. The method of claim 2, wherein, The large-particle material is detected to obtain the motion parameters and structure parameters of the large-particle material, in particular: A camera is arranged near the flume of the flume experimental device, and a dynamic image of the debris flow inside the flume is captured by the camera; the motion parameters and structure parameters of the large-particle material are obtained by analyzing the dynamic image of the debris flow.

8. The method of claim 7, wherein, According to the motion parameters of the large-particle material, the acting force characteristic parameters in the motion process of the large-particle material are determined, in particular: According to the motion trajectory and motion speed of the large-particle material, the drag force coefficient and friction coefficient in the motion process of the large-particle material are determined, and are used as the acting force characteristic parameters.

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