An auto cad-based method for estimating the dynamic reserves of slope material sources in flow-through areas of debris flows

Abstract

The application discloses a kind of mud-rock flow flow area slope surface source dynamic reserve estimation method based on AutoCAD, it is related to mountain disaster technical field, including the following steps: step one: collecting source body profile geometric data, constructs integrated source body profile geometric data, channel distribution length and the AutoCAD digital twin model of channel boundary topological relationship.Proposed by the present application "channel runoff strong water power direct scouring area + slumping response area + rainfall and slope runoff weak water power progressive erosion area" partition coupling mechanism, the erosion process is decomposed into multiple physical mechanism synergies, compared with previous method, the different destruction mode of different parts of slope collapse source body is considered, the demand of fine estimation of slope surface source dynamic reserve is met.

Description

Technical Field

[0001] This invention relates to the field of mountain disaster technology, specifically to a method for estimating the dynamic reserves of debris flow sources on slopes in debris flow zones based on AutoCAD. Background Technology

[0002] Debris flows are a common natural phenomenon in mountainous areas, causing enormous losses to my country every year. Rainfall, earthquakes, and other factors generate large amounts of landslide source material along gullies. These source materials are often carried agile in the debris flow path, becoming a significant source of debris flow material and exacerbating its destructive power. Estimating the initiation volume of these source materials under the influence of debris flows is an important engineering problem. Estimating the source volume and thus quantifying the destructive power of debris flows is of great significance, providing crucial parameters for debris flow engineering prevention and control, and meeting engineering requirements.

[0003] Currently, some methods exist for estimating the dynamic reserves of such individual debris sources. Qiao Jianping et al. (2012), in their academic paper "Discussion on Statistical Methods for Dynamic Reserves of Debris Flow Sources in the Most Seismically Affected Area of ​​the Wenchuan Earthquake," published in the *Chinese Journal of Geological Hazard Prevention*, refer to this type of source as gully lateral erosion-slide type debris sources and presents an estimation method for this type of source based on a graphical approach. They also calculate the initiation scale of this type of source based on soil erosion models (such as the RUSLE model) and field observation / experimental statistical models (CN105868442A). However, these methods do not consider the failure process of the slope landslide source body under debris flow action, nor do they consider the amount of soil generated during the landslide process, thus failing to meet the need for precise estimation of the initiation scale of a single slope landslide source body. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for estimating the dynamic reserves of debris flow sources on slopes in debris flow zones based on AutoCAD.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A method for estimating the dynamic reserves of debris flow source areas on slopes based on AutoCAD includes the following steps:

[0007] Step 1: Collect the geometric data of the material source body profile and construct an AutoCAD digital twin model that integrates the geometric data of the material source body profile, the channel distribution length, and the channel boundary.

[0008] Step 2: Based on the dynamic generation of water level lines in debris flow hydrodynamics, the critical instability point C between the water level line and the channel boundary is located using a boundary intersection algorithm, resulting in:

[0009] S1, the zone of direct scouring by strong hydrodynamics of channel runoff: a hydraulic shear zone bounded by the water level line, the outline of the landslide source body, and the channel boundary.

[0010] Step 3: Taking the critical instability point C as the origin of the landslide dynamics, a dynamic instability slope CD is derived along the direction of the soil's natural angle of repose, and a three-level erosion response domain is constructed in synergy:

[0011] S2: The chain-like instability zone enclosed by the water level, the channel boundary, and the dynamically unstable inclined plane CD;

[0012] S3: Slope erosion zone under the influence of rainfall and runoff with weak hydrodynamics after removing the source profiles of S1 and S2;

[0013] Step 4: Use AutoCAD's spatial analysis function to extract the vector area parameters of S1, S2, and S3;

[0014] Dynamically assigned erosion coefficient K: based on real-time mapping of a ternary parameter matrix of slope, rainfall intensity, and soil cohesion;

[0015] Step 5: Input the area parameters into the partitioned coupling model:

[0016] ;

[0017] Among them, regions S1, S2, and S3 correspond strictly to the model terms, reflecting the synergistic physical mechanisms of direct scouring by strong hydrodynamics of gully runoff, chain-like landslides, and gradual erosion by weak hydrodynamics of slope runoff.

[0018] Preferably, the AutoCAD digital twin model in step one is constructed in the following manner:

[0019] The geometric data of the material source body profile is analyzed into a polyline entity, the channel boundary is extracted as a closed spline curve, the spatial dependency matrix of the material source body and the channel boundary is established, the material source profile and the channel boundary are transformed into a surface region, and the intersection is obtained to generate the direct contact boundary.

[0020] Preferably, the boundary intersection algorithm in step two specifically includes:

[0021] Debris flow intensity can be dynamically simulated and calculated, categorized into 10-year, 20-year, 50-year, and 100-year return periods based on engineering design. Specific calculations can be performed using variations of the Manning formula.

[0022] ;

[0023] ;

[0024] Where Q is the flow rate, n is the Manning coefficient, B is the channel width, H is the channel water level depth, R is the hydraulic radius, S is the channel gradient, and A is the channel cross-sectional area.

[0025] Draw the water level line through the channel water level depth H, and obtain the critical instability point C between the water level line and the channel boundary.

[0026] Preferably, the method for generating the dynamic instability slope CD in step three is as follows: starting from the critical instability point C, draw a ray along the direction of the natural angle of repose of the soil, and intersect it with the contour line of the source body or the boundary of the previous erosion response domain at point D.

[0027] The natural angle of repose of the soil can be obtained through field experiments or indoor experiments.

[0028] Preferably, the three-level erosion response domains in step three are as follows:

[0029] S1: Direct scouring zone of strong hydrodynamic flow in gully: Direct scouring zone of strong hydrodynamic flow in flash flood / debris flow gully.

[0030] S2: The area where the soil in the strong hydrodynamic scouring zone of the gully is carried away by the material source and will naturally collapse due to its own weight, falling into the flash flood / debris flow and participating in the debris flow activity.

[0031] S3: Zone of gradual erosion due to weak hydrodynamics caused by rainfall and slope runoff. This zone is mainly characterized by erosion.

[0032] Preferably, the geometric shape of the weak hydrodynamic progressive erosion zone S3 in step three, formed by rainfall and slope runoff, satisfies the following:

[0033] It does not come into direct contact with the water level.

[0034] The landslide response zone S2 is subjected to a progressive retreat boundary.

[0035] Preferably, the dynamic erosion coefficient K in step four is 0.2-0.8 based on the real-time mapping of the ternary parameter matrix of slope-rainfall intensity-soil cohesion.

[0036] Preferably, when the slope is 15-25°, the rainfall intensity is <50mm / h, and the soil cohesion is >15kPa, the value of K is in the range of 0.2-0.4.

[0037] Preferably, when the slope is 25-35°, the rainfall intensity is 50-80 mm / h, and the soil cohesion is 10-15 kPa, the value of K is in the range of 0.4-0.6.

[0038] Preferably, when the slope is >35°, the rainfall intensity is >80mm / h, and the soil cohesion is <10kPa, the value of K ranges from 0.6 to 0.8.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] This invention proposes a zoned coupling mechanism consisting of "a strong hydrodynamic direct scouring zone S1 from gully runoff + a landslide response zone S2 + a weak hydrodynamic progressive erosion zone S3 from rainfall and slope runoff." This mechanism decomposes the erosion process into the synergistic effects of multiple physical mechanisms, clearly distinguishing the source initiation zones dominated by three different mechanisms: boundary intersection algorithm, cascading landslides, and weak hydrodynamic progressive erosion from slope runoff. This results in a more precise estimation of dynamic reserves that better reflects actual failure modes. Furthermore, this method combines soil mechanics theory with dynamic evolution processes, improving the accuracy of instability range prediction to a certain extent and enhancing the estimation of dynamic reserves. The error is effectively improved compared to traditional single-mechanism models. The division of the three-level erosion response domain is not a simple spatial segmentation, but a systematic design of "physical mechanism decoupling - spatiotemporal process differentiation - engineering scenario adaptation". This improves the ambiguity, singularity and lag of previous models in the characterization of erosion processes, improves the calculation accuracy and efficiency, and changes the limitation of traditional methods that only focus on the erosion process of fluid-particle interaction. It realizes a one-to-one correspondence between spatial partitioning and physical mechanisms, and considers the destruction process of slope landslide source bodies, which to a certain extent meets the needs of accurate estimation of slope source dynamic reserves. Attached Figure Description

[0041] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts. Wherein:

[0042] Figure 1 A graphical calculation model for the source body of slope collapse;

[0043] Figure 2 This is a shape diagram of the landslide material source 1 in the embodiment;

[0044] Figure 3 This is a shape diagram of the landslide material source 2 in the embodiment;

[0045] Figure 4 This is a shape diagram of the landslide material source 3 in the embodiment;

[0046] Figure 5 The diagram shows the model under different working conditions in the embodiment. Detailed Implementation

[0047] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0048] like Figure 1-5 As shown, a method for estimating the dynamic reserves of debris flow source areas on slopes based on AutoCAD includes the following steps:

[0049] Step 1: Collect the geometric data of the material source body profile and construct an AutoCAD digital twin model that integrates the geometric data of the material source body profile, the channel distribution length, and the channel boundary.

[0050] Specifically, the dimensions of the material source, cross-sectional dimensions, and channel dimensions are collected through actual reconnaissance, drilling, and lidar remote sensing. AutoCAD is then opened, and drawing tools such as polylines (PLINE), splines (SPLINE), or lines (LINE) are used to draw the boundaries of irregular areas, ensuring that the drawn graphic is a closed polygon or curve. The geometric data of the material source, the distribution length of the channel, and the boundary topological relationships are integrated into a unified AutoCAD topological model drawing to construct a dynamic digital twin that accurately reflects the spatial dependence between the material source and the channel, thus realizing the correlation between geometric data and dynamic parameters.

[0051] Step 2: Based on the dynamic generation of water level lines in debris flow hydrodynamics, the critical instability point C between the water level line and the channel boundary is located using a boundary intersection algorithm, resulting in:

[0052] S1, the zone of direct scouring by strong hydrodynamics of channel runoff: a hydraulic shear zone bounded by the water level line, the outline of the landslide source body, and the channel boundary.

[0053] Specifically, a variation of the Manning formula is used for calculation:

[0054] ;

[0055] ;

[0056] Where Q is the flow rate, n is the Manning coefficient, B is the channel width, H is the channel water level depth, R is the hydraulic radius, S is the channel gradient, and A is the channel cross-sectional area.

[0057] Based on the Manning formula, the highest water level line is dynamically generated through the channel water level depth H. On the AutoCAD topology model drawing constructed in step one, a vertical line with a length equal to the channel water level depth H is drawn using the polyline (PLINE) drawing tool, with the lowest point of the channel as the vertex. The end point of the vertical line is used to locate and draw a horizontal line perpendicular to the vertical line. This horizontal line is the highest water level line. The intersection of the highest water level line and the channel boundary is the critical instability point C. The strong hydrodynamic direct scouring zone S1 of the channel runoff is obtained, which is the hydraulic shear domain enclosed by the water level line, the contour of the landslide source body, and the channel boundary. The water level line is dynamically generated based on physical simulation, which is more consistent with the actual rainstorm debris flow process. The boundary intersection algorithm replaces manual experience judgment to achieve automatic, accurate, and rapid identification of the critical instability point.

[0058] Step 3: Taking the critical instability point C as the origin of the landslide dynamics, a dynamic instability slope CD is derived along the direction of the soil's natural angle of repose, and a three-level erosion response domain is constructed in synergy:

[0059] S2: The chain-like instability zone enclosed by the water level, the channel boundary, and the dynamically unstable inclined plane CD;

[0060] S3: Slope erosion zone under the influence of rainfall and runoff with weak hydrodynamics after removing the source profiles of S1 and S2;

[0061] Specifically, on the AutoCAD topology model drawing further constructed in step two, a ray is drawn using the polyline (PLINE) drawing tool with the critical instability point C as the origin and the natural angle of repose. The ray intersects the source contour at point D, thus obtaining the dynamic instability hypotenuse CD. This results in three closed regions on the AutoCAD topology model drawing, thereby constructing the landslide response zone S2 and the gradual erosion zone S3 caused by weak hydrodynamics from rainfall and slope runoff. Together with the strong hydrodynamic direct scouring zone S1 caused by gully runoff, a three-level erosion response domain is constructed. The direction of the dynamic hypotenuse is determined by the natural angle of repose, and its length and position dynamically affect the range of S2, making the model physically reasonable.

[0062] Furthermore, by proposing a zoned coupling mechanism of "direct hydrodynamic scouring zone S1 of gully runoff + landslide response zone S2 + gradual erosion by weak hydrodynamics of rainfall and slope runoff S3", the soil transport process is decomposed into the synergistic effect of multiple physical mechanisms:

[0063] S1: Zone directly impacted by strong hydrodynamic flow in the gully;

[0064] Slump response zone S2: Taking the critical point C as the origin, a dynamic instability slope CD is derived along the natural angle of repose, forming a "chain instability domain" enclosed by the water level line, the channel boundary, and CD. This simulates the chain collapse triggered by initial instability. By introducing the angle of repose through the slump response zone S2, the gravity instability chain reaction is reflected, which is in line with the principle of soil failure and makes the mechanical mechanism explicit. The partition definition of S2 closely combines the soil mechanical properties (natural angle of repose) and the instability dynamic process, quantifying and spatializing the dynamic process of chain collapse.

[0065] S3, a weak hydrodynamic progressive erosion zone caused by rainfall and slope runoff: The remaining part of the source contour represents the area that may be gradually eroded. The S3 zone is designed as a progressively receding shape to reflect the dynamic erosion process.

[0066] This method clearly distinguishes the source initiation areas dominated by three different mechanisms: direct scouring by strong hydrodynamics of gully runoff, chain landslides, and gradual erosion by weak hydrodynamics of rainfall and slope runoff. It provides a more refined estimation of dynamic reserves that better reflects actual failure modes. Furthermore, this method combines soil mechanics theory with dynamic evolution processes and proposes a quantitative division method for chain-like instability domains, which improves the accuracy of instability range prediction to a certain extent.

[0067] Step 4: Use AutoCAD's spatial analysis function to automatically extract the vector area parameters of S1, S2, and S3;

[0068] Dynamically assigned erosion coefficient K: based on real-time mapping of a ternary parameter matrix of slope, rainfall intensity, and soil cohesion;

[0069] Specifically, based on the AutoCAD topology model drawing obtained in step three, type AREA in the command line and press Enter. Follow the prompts to select each vertex of the irregular area in sequence. You can specify points by clicking with the mouse or entering coordinates, or you can directly select the object. After selecting all vertices, press Enter or right-click to end the command. The AutoCAD software will automatically calculate and display the area of ​​the selected area, reading the vector area (unit: ㎡) of the S1 / S2 / S3 regions respectively. The powerful geometric engine of professional AutoCAD software is seamlessly embedded into the analysis process, realizing efficient, accurate, and automated conversion of key geometric parameters (area), avoiding tedious and inefficient manual measurement or data export and import, and effectively improving calculation speed and accuracy.

[0070] Furthermore, based on the real-time assignment of the erosion coefficient K using the ternary parameter matrix of slope-rainfall intensity-soil cohesion, dynamic correction under the coupled effects of multiple environmental factors is achieved, replacing the traditional empirical constant values. Through automatic location of critical instability points, solution of three-level erosion domains, and dynamic assignment of erosion coefficients, the deviation of fixed coefficients is effectively avoided, further improving the calculation accuracy.

[0071] Step 5: Input the area parameters into the partitioned coupling model:

[0072] ;

[0073] Among them, regions S1, S2, and S3 correspond strictly to the model items, reflecting the synergistic physical mechanisms of direct scouring by strong hydrodynamics of gully runoff, chain landslides, and gradual erosion by weak hydrodynamics of rainfall and slope runoff.

[0074] Specifically, regions S1, S2, and S3 correspond strictly to model items:

[0075] S1: Strong hydrodynamic scouring of channel runoff → instantaneous start;

[0076] S2: Gravity collapse → short-term chain reaction failure;

[0077] S3: Weak hydrodynamic erosion from rainfall and slope runoff → Gradual erosion from short-duration rainfall and runoff;

[0078] The model structure itself reflects the different destruction modes of the source material by different instability / erosion mechanisms (direct scouring by strong hydrodynamics of gully runoff, chain landslides, and gradual erosion by weak hydrodynamics of rainfall and slope runoff). The correlation between the S2 and S3 zones reflects the positive feedback of scouring-induced landslides and landslides driving erosion. The contribution of each zone quantifies different erosion modes. The vector area parameters of S1, S2, and S3 are input into the zone coupling model, which strictly corresponds to different erosion mechanisms. This model design realizes a one-to-one correspondence between spatial zones and physical mechanisms, which not only considers the destruction process of the source material of slope collapses, but also improves the accuracy to a certain extent.

[0079] Furthermore, if the landslide source body is simplified to a triangular shape, the channel shape is uncertain, and its area is taken as... Then, the formula for calculating the starting volume of the landslide source body in the flash flood / debris flow zone is:

[0080] ;

[0081] Among them, S1 is the area directly scoured by strong hydrodynamics of flash flood / debris flow gully runoff; S2 is the soil in the area directly scoured by strong hydrodynamics of gully runoff that collapses naturally due to its own weight after being carried by the source material; and S3 is the area affected by rainfall and runoff. L represents the area of ​​the slope source body erosion triggered by rainfall and runoff, and L represents the length of the landslide source body along the debris flow channel. The angle of repose of the soil.

[0082] Based on the above calculation formula, it can be seen that this formula requires numerous parameters and is a simplified geometric calculation model, which does not conform to the complex shape of the actual slope landslide source body. Compared with previous calculation models, this is a relatively accurate manual calculation model that considers the failure process of the slope landslide source body. However, in practical engineering applications, using this simplified model is time-consuming and labor-intensive. Considering the powerful functions of industrial software AutoCAD, which can calculate the area of ​​arbitrary geometric shapes, a newly developed accurate estimation model combined with the functions of AutoCAD software can quickly estimate the starting volume of the slope landslide source body in the debris flow area, and the model can be simplified as follows:

[0083] ;

[0084] Furthermore, the simplified model is not simply a patchwork of known methods, but rather establishes a completely new correspondence between the physical mechanism of debris flow erosion and the mathematical model. It organically combines zone area, dynamic coefficient, and source thickness to form a logically rigorous and physically clear dynamic reserve calculation framework. It also works with the AutoCAD spatial engine to extract vector area, which can be directly integrated into the AutoCAD engineering design platform without the need for additional professional software. This lowers the threshold for geological hazard assessment and effectively reduces calculation time. While improving calculation accuracy and precision, it also effectively improves calculation efficiency, thus addressing the industry pain point of "high subjectivity and low accuracy in dynamic reserve estimation" to a certain extent.

[0085] Finally, calculate the total dynamic reserves of all material sources in the circulation area and output the estimated total dynamic reserves.

[0086] The AutoCAD digital twin model in step one is constructed in the following way:

[0087] The geometric data of the material source body profile is analyzed into a polyline entity, the channel boundary is extracted as a closed spline curve, the spatial dependency matrix of the material source body and the channel boundary is established, the material source profile and the channel boundary are transformed into a surface region, and the intersection is obtained to generate the direct contact boundary.

[0088] Specifically, the source body profile is analyzed as a multi-segment line entity (a vector object composed of continuous line segments and inflection points), which can accurately preserve the micro-geometric features such as slope undulation, lithological stratification interfaces, and local steep slopes. Compared with the "homogeneous rectangular / triangle simplified model" used in traditional methods, the multi-segment line entity can control the source body contour error within ±0.5m (based on the millimeter-level drawing accuracy of AutoCAD), and is especially suitable for the morphological restoration of heterogeneous source bodies such as fractured rock masses and layered soil masses.

[0089] Furthermore, the channel boundary is extracted as a closed spline curve (a smooth curve fitted by control points), which can realistically reproduce the meandering shape of natural channels (such as meandering sections and bottleneck sections), avoiding the "angularity error" caused by the polyline approximation.

[0090] Furthermore, the direct contact boundary (the overlapping line between the source body surface region and the channel boundary surface region) generated by the surface region intersection operation accurately locates the "starting line of direct contact between the source body and the channel". This boundary is not only the "initial erosion reference surface" of hydrodynamic action (the water flow first acts on this line and extends into the source body), but also the potential distribution area of ​​the subsequent critical instability point C. Compared with the subjectivity of "artificially delineating the reference line" in traditional methods, the objectivity of this boundary can effectively reduce the error in determining the initial erosion range.

[0091] The boundary intersection algorithm in step two specifically includes:

[0092] Debris flow intensity can be dynamically simulated and calculated, categorized into 10-year, 20-year, 50-year, and 100-year return periods based on engineering design. Specific calculations can be performed using variations of the Manning formula.

[0093] ;

[0094] ;

[0095] Where Q is the flow rate, n is the Manning coefficient, B is the channel width, H is the channel water level depth, R is the hydraulic radius, S is the channel gradient, and A is the channel cross-sectional area.

[0096] Draw the water level line through the channel water level depth H, and obtain the critical instability point C between the water level line and the channel boundary.

[0097] Specifically, based on the engineering design, the scenarios are divided into once-in-ten-year, once-in-twenty-year, once-in-fifty-year, and once-in-a-century events. The actual erosion thickness varies under different conditions, and the dynamic reserve scale under different conditions can be calculated based on the actual situation.

[0098] To calculate the erosion thickness Z under different working conditions, we can use the formula for calculating the thickness of the initiating layer shift in rock flow established by Japanese scholar Takahasi in 1978:

[0099] ;

[0100] in, These are the bulk density of solids and the bulk density of pure water, respectively. For flow depth; The inclination angle of the ditch; The macroscopic friction coefficient between particles; Shear resistance to water flow; This represents the average concentration of coarse particles along the vertical line.

[0101] like Figure 5 As shown, the erosion thicknesses Z1, Z2, and Z3 under different working conditions were calculated, and the erosion boundaries were drawn on the AutoCAD drawing based on the erosion thicknesses. The erosion boundaries were extended to intersect the waterline at C1, C2, and C3, respectively. Rays were drawn according to the natural angle of repose, intersecting the source contour at D1, D2, and D3, respectively, thus obtaining the dynamic instability hypotenuses C1D1, C2D2, and C3D3 under different working conditions. The areas were extracted from the AutoCAD topology model drawing, and the dynamic reserve volume of the source under different working conditions was calculated.

[0102] ;

[0103] ;

[0104] ;

[0105] ;

[0106] This allows for the estimation of actual material reserves based on different operating conditions, making the estimation results more consistent with reality and improving the general applicability of the calculation model.

[0107] The method for generating the dynamic instability slope CD in step three is as follows: starting from the critical instability point C, draw a ray along the direction of the natural angle of repose of the soil, and intersect it with the contour line of the source body or the boundary of the previous level erosion response domain at point D.

[0108] The natural angle of repose of the soil can be obtained through field experiments or indoor experiments.

[0109] The three-level erosion response domains in step three are as follows:

[0110] S1: Direct scouring zone of strong hydrodynamic flow in gully: Direct scouring zone of strong hydrodynamic flow in flash flood / debris flow gully.

[0111] S2: The area where the soil in the strong hydrodynamic scouring zone of the gully is carried away by the material source and will naturally collapse due to its own weight, falling into the flash flood / debris flow and participating in the debris flow activity.

[0112] S3: Zone of gradual erosion due to weak hydrodynamics caused by rainfall and slope runoff. This zone is mainly characterized by erosion.

[0113] Specifically, the strong hydrodynamic direct scouring zone S1 of the channel runoff: focusing on the direct effects of strong hydrodynamics in the channel (such as turbulent scouring and cavitation effects), the "initial area where water flow energy directly acts on the source body" is accurately delineated through hydrodynamic simulation and boundary intersection algorithm. Compared with the "uniform erosion assumption in the whole domain" in previous models, the delineation of this area further reduces the calculation error of scouring volume.

[0114] Slump response zone S2: Reveals the dynamic process of "water erosion → soil instability → chain collapse", and couples the soil self-weight effect with the hydrodynamic erosion effect through the instability slope CD derived from the natural angle of repose.

[0115] S3, a zone of gradual erosion by weak hydrodynamics in rainfall and slope runoff: This separates the gradual erosion process of slope runoff, characterized by "rainfall infiltration – runoff erosion – particle transport," to avoid confusion with sudden scouring and landslide processes. By independently assigning a low erosion coefficient K3, the "gradual erosion contribution" of short-term rainfall events to the source body can be quantified.

[0116] The three-level regions do not exist in isolation, but rather form an organic whole through spatial adjacency (S1→S2→S3) and failure processes (hydraulic scouring, structural instability, and runoff erosion). For example, after the soil in region S1 is scoured away, region S2 experiences a self-weight landslide due to the exposure of its free surface. The collapsed body then acts as a new roughness boundary, altering the runoff flow pattern in region S3. This "scouring-landslide-erosion" process makes the dynamic reserve estimation error more responsive to engineering requirements than traditional single-mechanism models.

[0117] Furthermore, the division of the three-level erosion response domain is not a simple spatial division, but a systematic design of "physical mechanism decoupling - spatiotemporal process differentiation". This improves the ambiguity, uniformity and lag of previous models in the characterization of erosion processes, improves the calculation accuracy and efficiency to a certain extent, and provides a certain scientific basis for debris flow prevention and control.

[0118] A method for constructing a weak hydrodynamic progressive erosion zone S3 based on rainfall and slope runoff, characterized in that: the geometric morphology of the weak hydrodynamic progressive erosion zone S3 in step three satisfies:

[0119] It does not come into direct contact with the water level.

[0120] The landslide response zone S2 is subjected to a progressive retreat boundary.

[0121] Specifically, the S3 zone, by defining itself as "not in direct contact with the water level," clearly separates the erosion process dominated by rainfall and low-intensity runoff on the slope. It complements the mechanisms of the S1 zone (direct hydrodynamic scouring of gully runoff) and the S2 zone (hydrodynamic erosion + self-weight collapse). By modeling the S3 zone independently, it can be accurately quantified, avoiding the overestimation error caused by previous models that classified it as "total water erosion."

[0122] Furthermore, the free surface formed by the landslide in zone S2 will change the stress state of the soil in zone S3 (such as the deflection of the principal stress direction and the concentration of shear stress). By simulating this traction effect through "progressive retreat boundary", the chain reaction of "local landslide → unloading of the soil behind → crack propagation → surface peeling" can be revealed. The method of constructing the progressive erosion zone S3 of weak hydrodynamics caused by rainfall and slope runoff makes up for the problem of insufficient characterization of "indirect strong hydrodynamic erosion process" in previous models through the triple control mechanism of "spatial isolation - stress traction - dynamic evolution".

[0123] The dynamic erosion coefficient K in step four is based on a real-time mapping of the ternary parameter matrix of slope, rainfall intensity, and soil cohesion, and its value ranges from 0.2 to 0.8.

[0124] When the slope is 15-25°, the rainfall intensity is <50mm / h, and the soil cohesion is >15kPa, the value of K ranges from 0.2 to 0.4.

[0125] When the slope is 25-35°, the rainfall intensity is 50-80 mm / h, and the soil cohesion is 10-15 kPa, the value of K ranges from 0.4 to 0.6.

[0126] When the slope is greater than 35°, the rainfall intensity is greater than 80 mm / h, and the soil cohesion is less than 10 kPa, the value of K ranges from 0.6 to 0.8.

[0127] Specifically, when the slope is greater than 35°, the K value increases to 0.6-0.8, directly reflecting the mechanism of "steep slopes accelerating the conversion of water flow energy into erosion kinetic energy". When the rainfall intensity is greater than 80 mm / h, the splashing kinetic energy of raindrops reaches 15-20 J / m²・min. Combined with the turbulent effect of surface runoff, the K value enters the high range of 0.6-0.8. For loose deposits with cohesion <10 kPa, the cementation force between particles is weak, and the K value is naturally higher by 0.6-0.8. The ternary parameter matrix forms a continuous K value distribution surface through interpolation, avoiding the abrupt error caused by the traditional "one-size-fits-all threshold". Traditional erosion models mostly use empirical coefficient superposition, while this scheme establishes a physical causal chain of "dynamic input (slope, rainfall intensity) - medium properties (cohesion) - erosion output (K value)" through the ternary parameter matrix. The technical solution of dynamically assigning the erosion coefficient K based on the ternary parameter matrix of slope-rainfall intensity-soil cohesion is beneficial to a certain extent for the refined estimation of erosion intensity quantification.

[0128] Example

[0129] A debris flow gully is located in the epicenter of the Wenchuan earthquake. Three typical slope landslide source bodies have developed in its debris flow area. A debris flow retaining dam is planned to be built downstream. The dynamic storage capacity of the debris flow gully slope source needs to be estimated. Its basic shape is as follows: Figure 2-4 .

[0130] Step 1: Obtain the cross-sectional dimensions of the three landslide material sources and the length of the landslide material sources distributed along the gully, and generate AutoCAD dimensional drawings.

[0131] Step Two: Based on the Manning formula and channel parameters, the water levels at three typical slope landslide source bodies under a 100-year debris flow scenario are calculated to be 6.2m, 6.8m, and 8m, respectively. The AutoCAD drawings of the slope landslide source body profiles are imported into AutoCAD software. The highest water level is drawn in AutoCAD software, and the intersection point with the channel boundary line on the side of the landslide source body is found. The area S1, defined by the water level line, the landslide source body outline, and the channel boundary line, is then obtained as a region of strong hydrodynamic scouring.

[0132] Step 3: Based on the field measurement of the natural angle of repose of the soil as 32°, draw the corner lines of each slope landslide source body. Thus, we obtain the debris flow water level line, the outline of the landslide source body, the area enclosed by the corner lines of the natural angle of repose, the landslide zone S2, and the remaining area as the weak hydrodynamic progressive erosion zone S3 caused by rainfall and slope runoff.

[0133] Step 4: Use the function of calculating the area of ​​a closed region in the CAD software to obtain the areas of S1, S2, and S3 respectively.

[0134] Slope landslide source body S1 / m2 S2 / m2 S3 / m2 1 507.3 0 0 2 452.6 187.4 106.9 3 439.3 50.1 63.5

[0135] Step 5: Input the obtained data into the calculation model The initiation volume of a single slope landslide source body can be obtained. Taking K as 0.4, the calculation yields:

[0136] ;

[0137] ;

[0138] ;

[0139] By summing up the starting volumes of all the landslide source bodies, the dynamic storage capacity of the landslide source bodies on the slope of the flow zone can be obtained:

[0140] .

[0141] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A method for estimating the dynamic reserves of debris flow path surface in debris flow zones based on AutoCAD, characterized in that, Includes the following steps: Step 1: Collect the geometric data of the material source body profile and construct an AutoCAD digital twin model that integrates the geometric data of the material source body profile, the channel distribution length, and the channel boundary; Step 2: Based on the dynamic generation of water level lines in debris flow hydrodynamics, the critical instability point C between the water level line and the channel boundary is located using a boundary intersection algorithm, resulting in: S1, the zone of direct scouring by strong hydrodynamics of channel runoff: a hydraulic shear zone bounded by the water level line, the outline of the landslide source body, and the channel boundary. Calculate using a variation of Manning's formula: ; Draw the water level line through the channel water level depth H, and obtain the critical instability point C between the water level line and the channel boundary; Step 3: Taking the critical instability point C as the origin of the landslide dynamics, a dynamic instability slope CD is derived along the direction of the soil's natural angle of repose, and a three-level erosion response domain is constructed in synergy: S2: The chain-like instability zone enclosed by the water level, the channel boundary, and the dynamically unstable inclined plane CD; S3: Slope erosion zone under the influence of rainfall and runoff with weak hydrodynamics after removing the source profiles of S1 and S2; The method for generating the dynamic instability slope CD is as follows: starting from the critical instability point C, draw a ray along the direction of the natural angle of repose of the soil, and intersect the contour line of the source body or the boundary of the previous level erosion response domain at point D. Step 4: Use AutoCAD's spatial analysis function to extract the vector area parameters of S1, S2, and S3; Dynamically assigned erosion coefficient K: determined based on slope, rainfall intensity, and soil cohesion; Step 5: Input the area parameters into the partitioned coupling model: ； in, This refers to the dynamic storage capacity of the slope in the debris flow zone. The length of the landslide source body along the debris flow channel.

2. The method for estimating the dynamic storage capacity of slope debris flow zone based on AutoCAD according to claim 1, characterized in that: The AutoCAD digital twin model in step one is constructed in the following way: The geometric data of the material source body profile is analyzed into a polyline entity, the channel boundary is extracted as a closed spline curve, the spatial dependency matrix of the material source body and the channel boundary is established, the material source profile and the channel boundary are transformed into a surface region, and the intersection is obtained to generate the direct contact boundary.

3. The method for estimating the dynamic reserves of debris flow path slopes based on AutoCAD according to claim 1, characterized in that: The boundary intersection algorithm in step two specifically includes: The intensity of debris flows is dynamically simulated and calculated, categorized into 10-year, 20-year, 50-year, and 100-year return periods based on engineering design. Specific calculations are performed using variations of the Manning formula. ； Where Q is the flow rate, n is the Manning coefficient, B is the channel width, H is the channel water level depth, R is the hydraulic radius, S is the channel gradient, and A is the channel cross-sectional area.

4. The method for estimating the dynamic storage capacity of slope sediment source in debris flow zones based on AutoCAD, as described in claim 1, is characterized in that: The natural angle of repose of the soil is obtained from field experiments or from indoor experiments.

5. The method for estimating the dynamic storage capacity of slope sediment source in debris flow zones based on AutoCAD, as described in claim 4, is characterized in that: The three-level erosion response domains in step three are as follows: S1: Direct scouring zone of strong hydrodynamic flow in gully: Direct scouring zone of strong hydrodynamic flow in flash flood / debris flow gully. S2: The area where the soil in the strong hydrodynamic scouring zone of the gully is carried away by the material source and will naturally collapse due to its own weight, falling into the flash flood / debris flow and participating in the debris flow activity. S3: Zone of gradual erosion due to weak hydrodynamics caused by rainfall and slope runoff. This zone is mainly characterized by erosion.

6. The method for estimating the dynamic storage capacity of slope sediment source in debris flow flow areas based on AutoCAD, as described in claim 5, is characterized in that: The geometric shape of the weak hydrodynamic progressive erosion zone S3 in step three, involving rainfall and slope runoff, satisfies the following: It does not come into direct contact with the water level. The landslide response zone S2 is subjected to a progressive retreat boundary.

7. The method for estimating the dynamic reserves of debris flow path slopes based on AutoCAD according to claim 1, characterized in that: The dynamically assigned erosion coefficient K in step four has a value range of 0.2-0.8 based on the real-time mapping of the ternary parameter matrix of slope-rainfall intensity-soil cohesion.

8. The method for estimating the dynamic reserves of debris flow path slopes based on AutoCAD according to claim 7, characterized in that: When the slope is 15-25°, the rainfall intensity is <50mm / h, and the soil cohesion is >15kPa, the value of K ranges from 0.2 to 0.

4.

9. The method for estimating the dynamic reserves of debris flow path slopes based on AutoCAD according to claim 7, characterized in that: When the slope is 25-35°, the rainfall intensity is 50-80 mm / h, and the soil cohesion is 10-15 kPa, the value of K ranges from 0.4 to 0.

6.

10. The method for estimating the dynamic storage capacity of slope debris flow zone based on AutoCAD according to claim 7, characterized in that: When the slope is >35°, the rainfall intensity is >80mm / h, and the soil cohesion is <10kPa, the value of K ranges from 0.6 to 0.8.

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