Method for calculating maximum amplitude of surge caused by high-position debris flow

Abstract

The invention provides a method for calculating the maximum amplitude of surges caused by high-position debris flow. The method comprises the steps that the effective wave making volume of the debris flow is obtained and calculated according to the landslide shear-out position, the debris flow width, the slip mass volume, the distance from the front edge of the slip mass to the water surface, the source area substance sliding angle and the moving slope angle of a source area; the maximum wave amplitude of the surge is calculated according to the effective wave making volume of the debris flow, the elevation of the landslide front edge of the high-position debris flow is usually large, so that the distance from the front edge of a slip mass to the water surface is larger than that of the conventional debris flow, the slip mass is disintegrated and granulated in the sliding process, the volume of the non-slip mass with the maximum wave amplitude of the surge is determined, and the maximum wave amplitude of the surge is determined. Therefore, the maximum wave amplitude of the surge is calculated by introducing the effective wave making volume, so that the calculation result is more suitable for the actual situation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of geological disaster prediction, and particularly relates to a method for calculating the maximum wave amplitude of a surge caused by a high-positioned debris flow. BACKGROUND

[0002] High-positioned debris flow refers to a landslide or collapse body that is affected by factors such as material composition, topographic path, and the like during movement, and exhibits a significant flow state characteristic, thereby being able to move at a high speed and over a long distance. When such a debris flow impacts a water area at the lower part of a mountain at a high speed from a slope with a large height difference, it can cause a severe surge secondary disaster. The surge can propagate upstream and downstream along a valley or river, and cause serious damage to local settlements, personnel, and public facilities after reaching a high area.

[0003] In the prior art, when calculating the maximum wave amplitude of a surge, the sliding surface of a source area and the slope surface along which the sliding body moves are often simplified as a whole for research and analysis, and the mutual relationship between the angle of the sliding surface and the angle of the sliding surface is not considered, which leads to a significant difference from the actual geological structure condition of the landslide / collapse debris flow, indirectly leads to unclear generation mechanism of the debris flow-surge, inaccurate prediction of disaster scale and surge size, and the like. At the same time, due to the long sliding distance of the high-positioned debris flow, the debris flow is prone to disintegration to form a granular body during the sliding process, which leads to a long water entry time and a more complex wave generation mechanism. However, the prior art usually regards the debris flow as a rigid body, simplifies the sliding environment and other conditions, and thus the calculation result does not conform to the actual result. SUMMARY

[0004] The purpose of the present application is to provide a method for calculating the maximum wave amplitude of a surge caused by a high-positioned debris flow, which can calculate the maximum wave amplitude of the surge that conforms to the actual result.

[0005] To solve the above problems, the present application provides a method for calculating the maximum wave amplitude of a surge caused by a high-positioned debris flow, comprising: S100: obtaining and calculating the effective wave-making volume of a debris flow according to the landslide cut-out position of a source area, the debris flow width, the volume of a sliding body, the distance from the front edge of the sliding body to the water surface, the material sliding angle of the source area, and the movement slope angle; S200: calculating the maximum wave amplitude of a surge according to the effective wave-making volume of the debris flow.

[0006] Further, the S100 in the method for calculating the maximum wave amplitude of a surge caused by a high-positioned debris flow comprises: S101: determining the movement slope angle according to the landslide cut-out position and the water entry point of a debris body; S102: calculating the debris flow width according to the debris flow cut-out width and the movement slope angle; S103: calculating the thickness of the debris flow impacting into water according to the width of the debris flow, the volume of the sliding body, the distance from the front edge of the sliding body to the water surface, the sliding angle of the source area material and the moving slope angle; S104: calculating the effective wave-generating volume according to the thickness of the debris flow impacting into water, the volume of the sliding body, the water depth, the width of the debris flow, the sliding angle of the source area material and the moving slope angle.

[0007] Further, the width of the debris flow in the calculation method of the maximum wave amplitude of the surge wave caused by the high-position debris flow is calculated by the following formula: (1) wherein, is the width of the debris flow, is the moving slope angle, is the width of the landslide shear.

[0008] Further, the thickness of the debris flow impacting into water in the calculation method of the maximum wave amplitude of the surge wave caused by the high-position debris flow is calculated by the following formula: (2) wherein, is the volume of the debris body, is the distance from the front edge of the sliding body to the water surface, is the sliding angle of the source area material.

[0009] Further, the effective wave-generating volume in the calculation method of the maximum wave amplitude of the surge wave caused by the high-position debris flow is calculated by the following formula: (3) wherein, is the effective wave-generating volume, is the water depth.

[0010] Further, the calculation formula of the maximum wave amplitude of the surge wave in S200 in the calculation method of the maximum wave amplitude of the surge wave caused by the high-position debris flow is: (4) wherein, is the maximum wave amplitude of the surge wave.

[0011] Further, the applicability representation parameter of formula (4) in the calculation method of the maximum wave amplitude of the surge wave caused by the high-position debris flow is: when being 0.1 to 2.59, the formula is applicable; The calculation formula of the applicability representation parameter is: (5) wherein, is the suitability characterization parameter, is the landslide front elevation, is the debris flow into water velocity, and its calculation formula is: (6) wherein, is the landslide surface friction coefficient.

[0012] The above technical solutions of the present application have the following beneficial technical effects: The landslide front elevation of high-position debris flow is usually large, so the distance from the front edge of the sliding body to the water surface is larger than that of conventional debris flow, and the sliding body will be disintegrated and granulated during the sliding process. Therefore, the maximum wave amplitude of the surge is not determined by the volume of the sliding body. Therefore, the effective wave-making volume is introduced to calculate the maximum wave amplitude of the surge, so that the calculation result is more in line with the actual situation. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a schematic view of the debris flow when it is not started according to the embodiment of the present application; Figure 2 is a schematic view of the debris flow when it impacts the water surface according to the embodiment of the present application; Figure 3 is a schematic view of the debris flow when the first wave crest is formed according to the embodiment of the present application; Figure 4 is a schematic view of the physical model test device structure according to the embodiment of the present application; Figure 5 is a flow chart of the method according to the embodiment of the present application. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solutions and advantages of the present application more clear and explicit, the present application will be further described in detail below with reference to the specific embodiments and the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of the known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0015] Debris flow with large landslide front elevation is usually called high-position debris flow. Compared with conventional debris flow, high-position debris flow will disintegrate during the sliding process, and can still continue to slide for a period of time after entering the water. The duration of the water entry process is about 3 times that of conventional debris flow. If it is still simplified as a rigid body for calculation, the prediction result of the maximum wave amplitude of the surge will deviate significantly.

[0016] As Figures 1-3As shown, this illustrates the entire process of a high-level debris flow from its initiation to the formation of the first wave crest. Based on the energy contribution mechanism, the maximum wave amplitude of the surge induced by the high-level debris flow is not directly determined by its total volume, but rather by the volume that has entered the water body before the first wave forms and leaves the disturbance area, i.e., the effective wave-generating volume. The maximum wave amplitude calculated using this effective wave-generating volume is in better agreement with the measured results, with a significantly reduced deviation.

[0017] To obtain data on the sliding process of high-level debris flow, a physical model experimental setup can be established at a scale of 1:300, such as... Figure 4 As shown in the diagram, the device consists of a water tank, a sliding surface, a motion path surface, a gate device, wave height meters, and a support frame. The water tank is 13m long, 2.3m high on the left side, and 0.4m wide. A high-speed camera is installed on the side of the water tank to capture the dynamic process of debris flowing into the water. The camera frame rate is automatically adjusted according to the experimental requirements, and the specific frame rate is determined through post-processing. Wave height meters G01-G06, with a sampling frequency of 50 Hz, are installed inside the water tank to record the wave height data of the surge caused by the debris flowing into the water. The wave height meters are arranged as follows: G01 is located 1m away from the boundary between the water surface and the motion path surface; wave height meters are placed every 0.5m between G01 and G04; and wave height meters are placed every 1m between G04 and G06. In addition, the angles of the motion path surface and the debris flow sliding surface inside the water tank can be adjusted according to the experimental requirements to meet the requirements of different experimental conditions.

[0018] To more accurately reflect real-world conditions, the physical model test setup included two adjustable-angle templates to simulate the slip surface of the debris flow source region and the slip surface of the debris material transported through rock strata. The debris material was selected with a density of 2300-2700 kg / m³ based on Froude's model test similarity theory. 3 The experiments used prismatic to sub-prismatic limestone granular materials and rigid concrete block specimens of different sizes. The experimental procedure followed the specifications of the "Model Test Specification for Water Transport Engineering" (STS / T 231-2021) and the "Technical Specification for Landslide Surge Simulation" (SL / T165-2019). Other controlling factors, such as starting elevation, sliding surface angle, slope angle, landslide volume, and water depth, all met the requirements for geometric similarity, kinematic similarity, and dynamic similarity. Data analysis relied on image geometry principles and particle image velocimetry (PIV) technology to extract key analytical data from each set of experiments, which were then used to analyze the maximum amplitude prediction formula for high-level debris flow-surge. Key analytical data included: effective wave-generating volume and effective wave-generating volume ratio, and data on debris particle velocity, impact thickness, and width.

[0019] After the experiment, the maximum wave amplitude calculation method of the surge caused by the high-position clastic flow is fitted based on the nonlinear regression method of the Levenberg-Marquardt (LM algorithm) theory according to the data obtained in the experiment.

[0020] Reference Figure 5 To solve the above problems, the application provides a maximum wave amplitude calculation method of a surge caused by a high-position clastic flow, which comprises the following steps: S100: obtaining and calculating the effective wave-making volume of the clastic flow according to the landslide cutting position of the source area, the clastic flow width, the sliding body volume, the distance from the sliding body front edge to the water surface, the source area material sliding angle and the movement slope angle; Specifically, S100 comprises the following steps: S101: determining the movement slope angle according to the landslide cutting position and the clastic body water entry point; S102: calculating the clastic flow width according to the clastic flow cutting width and the movement slope angle; The calculation formula of the clastic flow width is as follows: (1) wherein, the clastic flow width is W, the movement slope angle is a, and the landslide cutting width is W0.

[0021] S103: calculating the clastic flow impact water entry thickness according to the clastic flow width, the sliding body volume, the distance from the sliding body front edge to the water surface, the source area material sliding angle and the movement slope angle; The calculation formula of the clastic flow impact water entry thickness is as follows: (2) wherein, the clastic body volume is V, the distance from the sliding body front edge to the water surface is h, and the source area material sliding angle is β.

[0022] S104: calculating the effective wave-making volume according to the clastic flow impact water entry thickness, the sliding body volume, the water depth, the clastic flow width, the source area material sliding angle and the movement slope angle; The calculation formula of the effective wave-making volume is as follows: (3) wherein, the effective wave-making volume is V, and the water depth is h.

[0023] S200: calculating the maximum wave amplitude of the surge according to the effective wave-making volume of the clastic flow; The calculation formula of the maximum wave amplitude of the surge is as follows: (4) wherein, is the maximum amplitude of the surge wave.

[0024] To ensure the accuracy of the result of formula (4), it has a range of application, which is determined by the applicability characterization parameter, and the calculation formula of the applicability characterization parameter is: (5) wherein, is the applicability characterization parameter, is the front elevation of the landslide, is the velocity of the debris flow into the water, and the calculation formula is: (6) wherein, is the friction coefficient of the landslide surface.

[0025] Applicability characterization parameter When it is in the range of 0.1-2.59, formula (4) can be applied.

[0026] In reality, the source area is often a complex multi-segment slope, and the length-weighted average method can be used to determine the overall calculation angle, that is, the sliding angle of the source area material and the moving slope angle . The basis of this method is that the original complex topography will naturally tend to be smooth under the erosion of the debris material. Therefore, when calculating, the macro whole should be focused on, and the excessive influence of local features should be appropriately ignored.

[0027] Take the Chehalis Lake landslide which occurred on the northwest coast of Chehalis Lake in the southwest of British Columbia on December 4, 2007, as an example. According to the relevant data, the corresponding calculation parameters of the debris flow-surge wave amplitude are as follows: α = 36-40°; β = 30-32°; b0 = 210; V = 3.0 × 10 6 m 3 ; L ≈ 1123 m; h ≈ 100 m; a m ≈ 20 m; u s ≈ 60 m / s; H = 600 m. The calculation result shows that the applicability characterization parameter k = 1.62, which meets the calculation range requirement, and the maximum amplitude is 18.44 m, with an error of about 8% compared with the actual maximum amplitude, indicating that the calculation result has high precision.

[0028] It should be understood that the foregoing detailed description of the application, rather than limiting the application, is intended to explain and describe the current implementation of the application. Therefore, any modification, equivalent replacement or improvement made without departing from the spirit and scope of the application should be included in the protection scope of the application. In addition, the appended claims of the application are intended to cover all changes and modifications falling within the scope and boundary of the appended claims, or the equivalent form of such scope and boundary.

Claims

1. A method for calculating the maximum wave height of a surge generated by a high-level debris flow, characterized in that, The method comprises: S100: obtaining and calculating the effective wave-generating volume of the debris flow according to the landslide cutting position of the source area, the debris flow width, the volume of the sliding body, the distance from the front edge of the sliding body to the water surface, the sliding angle of the source area material, and the movement slope angle; S200: calculating the maximum wave amplitude of the surge wave according to the effective wave-generating volume of the debris flow.

2. The method for calculating the maximum wave amplitude of the surge wave caused by high-position debris flow according to claim 1, wherein: S100 comprises: S101: determining the movement slope angle according to the landslide cutting position and the water entry point of the debris body; S102: calculating the debris flow width according to the debris flow cutting width and the movement slope angle; S103: calculating the water entry thickness of the debris flow according to the debris flow width, the volume of the sliding body, the distance from the front edge of the sliding body to the water surface, the sliding angle of the source area material, and the movement slope angle; S104: calculating the effective wave-generating volume according to the water entry thickness of the debris flow, the volume of the sliding body, the water depth, the debris flow width, the sliding angle of the source area material, and the movement slope angle.

3. The method for calculating the maximum wave amplitude of the surge wave caused by high-position debris flow according to claim 2, wherein: The calculation formula of the debris flow width is: （1） wherein, is the debris flow width, is the moving slope angle, is the landslide shear-out width.

4. The method for calculating the maximum wave amplitude of the surge wave caused by high-position debris flow according to claim 3, wherein: The calculation formula of the water entry thickness of the debris flow is: （2） wherein, is the volume of the debris body, is the distance from the front of the slide body to the water surface, is the angle of the source zone material slide.

5. The method for calculating the maximum wave amplitude of the surge wave caused by high-position debris flow according to claim 4, wherein: The calculation formula of the effective wave-generating volume is: （3） wherein, is the effective wave making volume, is the water depth.

6. The method for calculating the maximum wave amplitude of the surge wave caused by high-position debris flow according to claim 5, wherein: The calculation formula of the maximum wave amplitude of the surge wave in S200 is: （4） wherein is the maximum wave amplitude of the swell.

7. The method for calculating the maximum wave amplitude of the surge wave caused by high-position debris flow according to claim 6, wherein: Applicability of the formula (4) to the characterization parameter Applicable when in the range 0.1-2.59; The calculation formula of the applicability representation parameter is: （5） wherein, is the suitability characterization parameter, is the landslide front elevation, is the debris flow into water velocity, calculated as: （6） wherein is the coefficient of sliding surface friction.

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