A method for optimizing design of a drainage ditch based on terrain data

Abstract

The application discloses a kind of based on topographic data's drainage ditch optimization design method, it is related to drainage ditch technical field, including the following steps: obtaining high-precision topographic vector data of study area;Original topographic vector data in drainage ditch area is cut out by CAD;The number of groove bottom contour line of drainage ditch, contour interval and elevation are calculated;Through ArcGIS software, the grid conversion of groove bottom elevation data and the high-precision topographic vector data after cutting is carried out to obtain the DEM data of study area containing drainage ditch bottom surface;Drainage ditch dike is converted into drainage ditch dike grid data;The data of both are added, and the final DEM data is obtained;Numerical simulation is carried out to the final DEM data, and according to simulation result, optimization design is carried out to drainage ditch.The application can directly see the prevention and treatment effect of drainage ditch of different height and different width based on high-resolution numerical simulation, and the optimal height and width of drainage ditch can be selected, to realize the maximization of prevention and treatment benefit.

Description

Technical Field

[0001] This invention relates to the field of drainage channel technology, and in particular to a drainage channel optimization design method based on terrain data. Background Technology

[0002] Debris flow diversion channels are among the most widely used engineering measures for debris flow disaster prevention worldwide due to their simple structure, good prevention effect, availability of local materials, convenient construction and maintenance, long service life, and low cost. Debris flow diversion projects play a crucial role in mitigating these disasters. However, the effectiveness of diversion channels is influenced by topography, geomorphology, and hydrological conditions, which are often difficult to consider during the design process. Consequently, diversion channels frequently fail to meet the flow requirements of debris flows, leading to overflow problems, or even failure to be installed along the debris flow path. This poses significant risks to the reliability and safety of debris flow diversion projects, necessitating research on design optimization and effectiveness evaluation of debris flow diversion channels.

[0003] The overflow problem of debris flow drainage channels is mainly caused by the insufficient width or height of the channels, resulting in inadequate flow capacity. The width of the drainage channel is generally the same as the original channel width, and its flow capacity is usually determined by the channel height. Channel height is one of the most important parameters in drainage channel design, directly determining the flow capacity and engineering benefits. Optimizing the design of debris flow drainage channels in complex mountainous terrain is quite difficult. Previous research has mainly focused on the following three aspects: First, case study statistical analysis. Case studies mainly involve field investigations of typical debris flow events, investigating and statistically analyzing the overflow situation of drainage channels and the debris flow path, and feeding the analysis results back into the design of future debris flow drainage channels. However, the nature of debris flows varies regionally, and the case study results are difficult to generalize due to the limited sample size of the statistical analysis. Second, model tests. Model tests mainly guide experimental design by statistically analyzing existing debris flow characteristics and the main design parameters of debris flow drainage channels, using indoor flume model tests to optimize the design and evaluate the effectiveness of debris flow disaster drainage channels. However, debris flow disasters have scale effects and boundary effects, and the results of model tests may differ significantly from actual conditions. Thirdly, numerical simulation. Numerical simulations are mostly based on simplified analyses of various resistances within the debris flow, establishing corresponding mathematical models; on this basis, the velocity distribution and mechanical state distribution of the debris flow under certain conditions are calculated; finally, the flow path, ejection characteristics, and flow state of the drainage channel section of the debris flow are solved. Previous numerical simulation studies have mainly focused on the ejection characteristics of debris flows, with less attention paid to the optimization design of drainage channels. Summary of the Invention

[0004] This invention provides a method for optimizing the design of drainage channels based on terrain data, which can solve the problems existing in the prior art.

[0005] This invention provides a method for optimizing the design of drainage channels based on terrain data, comprising the following steps:

[0006] Obtain topographic vector data of the study area;

[0007] The original terrain vector data within the drainage channel area is cropped using CAD software to obtain cropped terrain vector data.

[0008] Calculate the number of contour lines, contour interval, and elevation of the bottom of the drainage channel; and lay out the bottom contour lines in the proposed drainage channel area based on the number of contour lines and contour interval.

[0009] The DEM data of the study area, including the bottom surface of the drainage channel, was obtained by raster conversion of the bottom elevation data of the channel and the cropped terrain vector data using ArcGIS software.

[0010] The drainage channel embankment was converted into drainage channel embankment raster data using ArcGIS software.

[0011] The DEM data of the study area, including the bottom surface of the drainage channel, was added to the grid data of the drainage channel embankment using a grid calculator to obtain the final DEM data of drainage channels with different widths and heights.

[0012] The final DEM data was numerically simulated using RAMMS software, and the design of the guide channel was optimized based on the simulation results.

[0013] Preferably, the number of contour lines at the bottom of the guide channel is calculated according to the formula for calculating the number of contour lines, as shown in the following formula:

[0014] N = L / B

[0015] In the formula, N is the number of contour lines, L is the length of the guide groove, and B is the spacing between the contour lines at the bottom of the groove.

[0016] Preferably, the contour interval of the guide channel is calculated according to the contour interval calculation formula, as shown below:

[0017] H4 = H3 / N

[0018] H3 = H1 - H2

[0019] In the formula, H4 is the contour interval, H1 is the starting elevation of the debris flow direction, H2 is the ending elevation of the debris flow direction, and H3 is the relative elevation difference.

[0020] Preferably, the elevation of the guide channel is calculated according to the elevation calculation formula, as shown below:

[0021] H Ni =H1-H4(i-1)

[0022] In the formula, HN1 is the elevation of the contour line, and i is the contour line number.

[0023] Preferably, when performing numerical simulation of the final DEM data using RAMMS software, it is necessary to calculate the motion characteristic parameters of the debris flow, including the fluid thickness H and the flow velocity U.

[0024] Preferably, the fluid thickness H is determined according to the following formula:

[0025]

[0026] in,

[0027] Q = K·T·Q c

[0028] Q c =W c V c

[0029]

[0030] In the formula: U x U is the velocity in the X direction; y Let V be the velocity in the Y direction, t be the transpose of the average velocity matrix, and V be the velocity in the Y direction. c n represents the average velocity (m / s) across the debris flow cross section. c H represents the roughness of the debris flow gully bed. c Where I is the debris flow mud level (m), I is the slope of the debris flow cross-section, and W is the mud level. c The cross-sectional area of ​​the debris flow (m²) 2 ), Q c Debris flow rate (m³) 3 / s), T is the duration of the debris flow (s), and the K value varies with the size of the watershed area. When F < 5km 2 When K = 0.202, and 5km² <F<10km 2 When K = 0.113, and 10 km² <F<100km 2 At that time, K = 0.0378.

[0031] Preferably, the flow velocity U is determined according to the following formula:

[0032] U (x,y,t) =[U X(x,y,t) U Y(x,y,t) ] T

[0033]

[0034]

[0035] In the formula: ‖U‖ represents taking the absolute average value of U, T is the transpose matrix symbol for the average velocity, ensuring that U is a strictly positive velocity in the vector space, and n u Indicates the direction of flow.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] (1) It can effectively obtain the flow path of debris flow before the construction of drainage channels. In the past, we could only subjectively infer the flow path of the next debris flow based on the flow path of the debris flow that has occurred and personal experience. It can also intuitively show the flow guiding effect of drainage channels of different widths and heights on debris flow, and evaluate whether it can effectively protect the lives and property of residents on both sides of the valley.

[0038] (2) Numerical simulation can intuitively show the prevention and control effect of drainage channels with different heights and widths, that is, the flow path, flushing characteristics and flow state of the drainage channel section of debris flow under different heights and widths. The optimal height and width of the drainage channel can be selected to maximize the prevention and control benefits. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0040] Figure 1 This is an overall flowchart of a topographic data-based optimization design method for drainage channels according to the present invention.

[0041] Figure 2 (a) is a schematic diagram of the original terrain vector data for numerical simulation of the present invention;

[0042] Figure 2 (b) is a schematic diagram of the contour lines of the bottom of the drainage channel, the range of the channel embankment, and the original terrain vector data after the drainage channel area is trimmed according to the present invention.

[0043] Figure 2 (c) is a schematic diagram of the DEM data after the proposed guide channel is superimposed according to the present invention. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Reference Figure 1-2 This invention discloses an optimization design method for drainage channels based on topographic data. This invention mainly simulates the prevention and control effect of drainage channels on the mouth section of debris flows; therefore, only a high-precision three-dimensional model of the mouth section is established. Specifically, it includes the following steps:

[0046] Step 1: Obtain high-precision topographic vector data of the study area based on field surveys, including contour lines, elevation points, and cliff data.

[0047] Step 2: Use CAD software to trim the original terrain vector data within the drainage channel area to obtain high-precision terrain vector data after trimming;

[0048] Step 3: Calculate the number, contour interval, and elevation of the bottom contour lines of the drainage channel. Based on the number and contour interval of the bottom contour lines, lay out the bottom contour lines within the proposed drainage channel area. Draw the starting line of the bottom contour lines at the starting point of the drainage channel. The length of the starting line is the width of the bottom of the drainage channel, set as required. In CAD, use the set spacing and number to array the bottom contour lines along the path. After laying out, import it into ArcGIS, convert the bottom contour line layer into a shapefile, and add an elevation field to the shapefile features.

[0049] Calculate the number of contour lines at the bottom of the guide channel using the following formula:

[0050] N = L / B (1)

[0051] In the formula, N is the number of contour lines, L is the length of the guide groove, and B is the spacing between the contour lines at the bottom of the groove.

[0052] The contour interval of the guide channel is calculated using the following formula:

[0053] H4 = H3 / N (2)

[0054] H3 = H1 - H2 (3)

[0055] In the formula, H4 is the contour interval, H1 is the starting elevation of the debris flow direction, H2 is the ending elevation of the debris flow direction, and H3 is the relative elevation difference.

[0056] Calculate the elevation of the guide channel using the following formula:

[0057] H Ni =H1-H4(i-1) (4)

[0058] In the formula, H N1 is the elevation of the contour line, and i is the contour line number.

[0059] Step 4: Using ArcGIS software, raster conversion is performed on the trench bottom elevation data and the cropped high-precision terrain vector data to obtain DEM data of the study area including the bottom of the drainage trench. The ArcGIS terrain-to-raster function is used to input contour lines and elevation points outside the drainage trench area, as well as contour lines at the trench bottom, to generate DEM data excluding the drainage trench embankment.

[0060] Step 5: Use ArcGIS software to convert the drainage channel embankment into raster data. Add different design height fields to the embankment area shapefile and convert it into raster data using the area-to-raster function.

[0061] Step 6: Use a grid calculator to add the DEM data of the study area containing the bottom of the drainage channel to the grid data of the drainage channel embankment, and finally obtain the final DEM data of drainage channels with different widths and heights;

[0062] Step 7: Perform numerical simulation on the final DEM data using RAMMS software. Numerical simulation using this DEM data can obtain the debris flow prevention effect under different widths and heights of drainage channels. Optimize the design of the drainage channels based on the simulation results.

[0063] RAMMS is a dynamic numerical simulation software developed by the Swiss Federal Institute for Snow and Avalanche Research to simulate gully-type or slope-type debris flows. It is primarily used to simulate the movement process of debris flows and their ejection characteristic parameters. Therefore, RAMMS can be used to simulate debris flow processes. This model can predict the spatial distribution of debris flow path, velocity, depth, pressure, and other data in a two-dimensional or three-dimensional environment. The RAMMS model treats debris flows as fluids with rheological properties, which allows for a relatively good simulation of the debris flow process and the acquisition of debris flow ejection characteristic parameters.

[0064] RAMMS uses a Cartesian coordinate system: x, y, and elevation z, where t is the time of debris flow movement. The motion characteristics of debris flows are represented by two main parameters: fluid thickness H(x,y,t) and flow velocity U(x,y,t).

[0065] The magnitude of the flow velocity is determined by the following formula:

[0066] U (x,y,t) =(U X(x,y,t) U Y(x,y,t) (5)

[0067]

[0068] The direction of the flow velocity is

[0069]

[0070] The flow depth is determined by the following formula

[0071]

[0072] To simulate debris flows in a gully, it is necessary to input debris flow characteristic values ​​such as flow rate, velocity, and total volume at a given location. There are two methods to obtain the flow rate at a given location: one is to calculate the flow rate by measuring the cross-sectional area and mud level at the given location; the other is to calculate the flow rate based on the empirical relationship between debris flow flow rate and estimated total debris flow volume. The general formula for viscous debris flows is used to calculate the velocity, and the morphological survey method is applied to calculate the debris flow flow rate at a given location.

[0073]

[0074] Q c =W c V c (10)

[0075] In the formula: V c n represents the average velocity (m / s) across the debris flow cross-section. c H is the roughness of the debris flow channel bed; H is the debris flow mud level (m); I is the slope of the debris flow cross-section channel bed; W c The cross-sectional area of ​​the debris flow (m²) 2 );Q c Debris flow rate (m³) 3 / s).

[0076] The total volume Q of a debris flow is calculated based on the debris flow duration T (s) and the maximum flow rate Qc (m³). 3 / s), based on the characteristics of rapid rise and fall of debris flows, the process is generalized into a pentagon and calculated using the following formula:

[0077] Q = K·T·Q c (11)

[0078] In the formula: the value of K varies with the size of the watershed area (F).

[0079] K—when F < 5km 2 At that time, K = 0.202;

[0080] When 5km2 <F<10km 2 At that time, K = 0.113;

[0081] When 10km2 <F<100km 2 At that time, K = 0.0378;

[0082] T — Duration of debris flow (s).

[0083] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0084] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for optimizing the design of drainage channels based on terrain data, characterized in that, Includes the following steps: Obtain topographic vector data of the study area; The original terrain vector data within the drainage channel area is cropped using CAD software to obtain cropped terrain vector data. Calculate the number of contour lines, contour interval, and elevation of the bottom of the drainage channel; and lay out the bottom contour lines in the proposed drainage channel area based on the number of contour lines and contour interval. The DEM data of the study area, including the bottom surface of the drainage channel, was obtained by raster conversion of the bottom elevation data of the channel and the cropped terrain vector data using ArcGIS software. The drainage channel embankment was converted into drainage channel embankment raster data using ArcGIS software. The DEM data of the study area, including the bottom surface of the drainage channel, was added to the grid data of the drainage channel embankment using a grid calculator to obtain the final DEM data of drainage channels with different widths and heights. The final DEM data was numerically simulated using RAMMS software, and the design of the guide channel was optimized based on the simulation results.

2. The method for optimizing the design of drainage channels based on terrain data as described in claim 1, characterized in that, The number of contour lines at the bottom of the guide channel is calculated using the formula shown below: In the formula, N The number of contour lines. L For the length of the guide groove, B The spacing between the contour lines at the bottom of the trench.

3. The method for optimizing the design of drainage channels based on terrain data as described in claim 2, characterized in that, The contour interval of the guide channel is calculated using the contour interval calculation formula, as shown below: In the formula, H 4 For contour intervals, H 1 The elevation of the starting point in the direction of debris flow. H 2 This represents the elevation of the endpoint of the debris flow direction. H 3 This refers to the relative elevation difference.

4. The method for optimizing the design of drainage channels based on terrain data as described in claim 3, characterized in that, The elevation of the guide channel is calculated using the elevation calculation formula, as shown below: In the formula, H Ni This represents the elevation of the contour lines. i These are the contour line numbers.

5. The method for optimizing the design of drainage channels based on terrain data as described in claim 1, characterized in that, When performing numerical simulations on the final DEM data using RAMMS software, it is necessary to calculate the kinematic characteristic parameters of the debris flow, including the fluid thickness H and the flow velocity. .

6. The method for optimizing the design of drainage channels based on terrain data as described in claim 5, characterized in that, The fluid thickness H is determined according to the following formula: in, In the formula: Velocity in the X direction; Velocity in the Y direction; V c denoted as the average velocity across the debris flow cross section, in m / s; n c The roughness of the debris flow gully bed; The mud level of the debris flow is in meters. I c For the slope of the gully bed in the debris flow section; W c The cross-sectional area of ​​the debris flow is m. 2 ; Q c The debris flow rate is m. 3 / s; T is the duration of the debris flow, in seconds; the K value varies with the size of the watershed area, when F < 5km 2 When K=0.202, and 5km 2 <F<10km 2 At that time, K=0.113, when 10km 2 <F<100km 2 At that time, K=0.0378, t represents the total volume of the debris flow and t represents the time it takes for the debris flow to travel.

7. The method for optimizing the design of drainage channels based on terrain data as described in claim 6, characterized in that, The flow velocity Determined according to the following formula: In the formula: Indicates to Take the absolute average value, where T is the sign of the transpose matrix of the average velocity, ensuring... In vector space, it becomes a strictly positive velocity. Indicates the direction of flow.

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