Landslide motion analysis method based on unmanned aerial vehicle remote sensing and three-dimensional geological modeling

Abstract

The invention relates to a landslide motion analysis method based on unmanned aerial vehicle remote sensing aerial survey and three-dimensional geological modeling, which comprises the following steps: acquiring high-resolution topographic data of a landslide hidden danger area by utilizing a laser scanner technology carried by an unmanned aerial vehicle, and calculating landslide instability failure ranges and stability coefficients under different scenes by utilizing finite element Geostudio software; and taking the stability coefficient as a reduction coefficient of a rock-soil body strength parameter, then determining the rock-soil body strength parameter under different scenes in discrete element PFC software, and realizing three-dimensional failure motion process analysis of the landslide under different scenes by using discrete elements. According to the invention, through PFC software, landslide occurrence scales under different rainfall and earthquake scenes and motion characteristics of landslides of different scales after instability can be compared; large deformation under the fluid-solid coupling condition can be effectively simulated, rock-soil body strength parameters under different rainfall (or earthquake) scenes can be determined, and the landslide three-dimensional motion process under different scenes can be carried out.

Description

Technical Field

[0001] The present invention relates to the field of engineering geological research, and in particular to a landslide motion analysis method based on unmanned aerial vehicle remote sensing and three-dimensional geological modeling. Background Art

[0002] The formation of landslides is related to many factors, including geological structure, topography, soil properties, rainfall, groundwater level changes, seismic activity, human engineering activities, etc. Among them, rainfall is the most common factor that triggers landslides, especially after continuous rainfall or heavy rainfall, the soil moisture increases and the shear strength of the soil decreases, thereby increasing the probability of landslides. This type of disaster is often sudden, destructive and difficult to predict. Therefore, it is very necessary to accurately and timely predict the disaster of landslides caused by rainfall.

[0003] However, the current assessment of landslide movement and its hazards mainly focuses on retrospective analysis of landslides that have already occurred, that is, comparing the calculation results of numerical simulation methods with known actual results. These landslide cases usually have detailed field investigation information and survey data. However, there is still no effective method to predict the movement process of landslide potential points under specific rainfall conditions and different earthquake situations where disasters have not yet occurred. In particular, there is a lack of a landslide disaster prediction framework that combines multiple technical means such as remote sensing and numerical simulation, making it difficult to realize landslide movement analysis under different rainfall scenarios and different earthquake scenarios. Summary of the invention

[0004] In view of the shortcomings of the prior art, the technical problem that the present invention intends to solve is to provide a landslide movement analysis method based on UAV remote sensing aerial survey and three-dimensional geological modeling, aiming to solve the problem that it is difficult to accurately predict the three-dimensional movement of landslides under different existing scenarios (such as rainfall of different intensities, earthquakes). The technology of the present invention has important scientific reference value for formulating effective landslide prevention and control strategies.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is specifically as follows: A landslide motion analysis method based on UAV remote sensing aerial survey and three-dimensional geological modeling, the process of the method is: S1. Use drones to obtain high-resolution remote sensing images of the landslide hazard investigation area, generate digital elevation models (DEMs), orthophotos and tilt models of the investigation area, and obtain the terrain conditions and high-resolution terrain data of the landslide hazard points; S2, the digital elevation model of step S1 is converted and imported into Geostudio software to generate Geostudio landslide model, the seepage field of the slope under different rainfall scenarios is calculated in the SEEP / W module of Geostudio software, and the stability analysis is performed using the SLOPE / W module to obtain the sliding surface position and stability coefficient of the landslide potential point under different rainfall scenarios, thereby determining the damage range of the landslide; in the QUAKE / W stress analysis module of Geostudio software, the initial stress of the slope, the initial pore water pressure and the input lateral earthquake acceleration data are set as the parent directory, and then the slope stability analysis under different earthquake scenarios is performed in combination with the Newmark deformation module, thereby obtaining the sliding surface position and stability coefficient of the landslide potential point under the scenario, thereby determining the damage range of the landslide under different earthquake scenarios; S3, using the high-resolution terrain data of the landslide potential point obtained in step S1, a three-dimensional geological model of the landslide is established in the PFC3D software by using ball-wall contact, wherein the sliding surface in the three-dimensional geological model of the landslide is determined by S2, and the sliding bed in the three-dimensional geological model of the landslide is determined based on the damage range of the landslide obtained in S2; Step S2: after obtaining the stability coefficient of the landslide potential point under different rainfall scenarios and different earthquake scenarios, the stability coefficient is used as the strength reduction coefficient of the rock and soil strength parameter of the landslide, and the strength parameter value of the rock and soil under natural working conditions is multiplied by the corresponding strength reduction coefficient to obtain the strength parameter value under different rainfall scenarios and different earthquake scenarios; the rock and soil strength parameter value under natural working conditions is the data determined by experience or experiment when there is no rainfall and earthquake; The landslide body is discretized into particles, and the discrete element particles in PFC are assigned with the strength parameter values ​​of the corresponding scenarios to obtain the three-dimensional geological model of the landslide under different scenarios. S4. Based on the three-dimensional geological model of the landslide under different scenarios obtained in step S3, the initial conditions and boundary conditions of the landslide are set in the PFC3D software to perform numerical simulation on the landslide, and the velocity, displacement, and three-dimensional motion range diagram under different scenarios are output to analyze the three-dimensional motion characteristics of the landslide under different scenarios.

[0006] Furthermore, the three-dimensional movement characteristics of the landslide under different scenarios are analyzed, including the movement speed, displacement, movement range and accumulation depth of the landslide particles, and the possible movement range and maximum movement speed of the landslide under different scenarios are compared, thereby comparing the landslide hazards under different scenarios.

[0007] Furthermore, the rock and soil strength parameter values ​​include damping coefficient, friction coefficient, cohesion and internal friction angle, etc.

[0008] Furthermore, the drone is a DJI Mavic 3E drone equipped with an RTK module. When the drone plans a route, two routes with a certain degree of overlap are used to achieve oblique photography, and the overlap is 50-80%.

[0009] Compared with the prior art, the present invention has the following beneficial effects: (1) Previous studies have mostly been retrospective analysis or reverse analysis of the movement process of landslides that have occurred. The present invention mainly focuses on landslide potential points, and uses the laser scanner technology carried by drones to quickly and accurately obtain high-resolution terrain data of landslide potential areas. Landslide potential points usually have not undergone detailed on-site investigations and accurate survey data. Therefore, based on the characteristics of finite element software that can perform fluid-solid coupling analysis, the present invention uses Geostudio software to analyze the instability range of landslide potential points under different rainfall scenarios and earthquake scenarios, and can accurately determine the landslide damage range and sliding surface under different scenarios.

[0010] (2) Finite element software cannot effectively simulate large deformation and landslide movement, and discrete element software cannot consider different rainfall infiltration conditions. The present invention combines Geostudio with PFC for coupling analysis, uses Geostudio to analyze the stability of landslides under different rainfall scenarios and earthquake scenarios, uses the stability coefficient of landslide potential points as the strength reduction coefficient, and then uses this coefficient to reduce the strength of geotechnical parameters in the discrete element PFC software under the corresponding scenario, so as to obtain the strength parameters of landslide rock and soil under different scenarios, which can be used to calculate the movement process analysis after the landslide becomes unstable.

[0011] (3) Using high-resolution image data obtained by UAV remote sensing, a three-dimensional geological model of the landslide is established in PFC. In reality, only analysis on a three-dimensional scale can accurately reflect the movement process of the landslide after instability, so as to accurately predict the movement characteristics and danger of the landslide. Based on the strength parameters of the landslide rock and soil under different scenarios determined above, the three-dimensional movement process of the landslide under different rainfall and earthquake scenarios is analyzed. The main analysis is on the two indicators of landslide movement range and movement speed, so that the danger of landslides under different scenarios can be accurately predicted and compared.

[0012] The present invention uses the laser scanner technology carried by the unmanned aerial vehicle to obtain high-resolution terrain data of the landslide hazard area, uses the finite element Geostudio software to calculate the instability damage range and stability coefficient of the landslide under different scenarios (different rainfall, earthquake), uses the stability coefficient as the reduction coefficient of the rock and soil strength parameter, and then determines the rock and soil strength parameters under different scenarios in the discrete element PFC software, and uses the discrete element to realize the three-dimensional destruction motion process analysis under different landslide scenarios. The present invention can compare the scale of landslide occurrence (landslide movement range and movement speed) under different rainfall and earthquake scenarios, and the movement characteristics of landslides of different scales after instability through the PFC software. For the landslide hazard point, it can effectively simulate the large deformation under fluid-solid coupling conditions, determine the rock and soil strength parameters under different rainfall (or earthquake) scenarios, and carry out the three-dimensional motion process of the landslide under different scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 UAV routes (a), (b) and obtained DEM data (c) and tilt model of landslide hazard points (d).

[0014] Figure 2 This is a diagram of the damage range and stability coefficient of landslide potential points under a 50-year return period rainfall.

[0015] Figure 3 Three-dimensional motion diagram of the landslide under a 50-year return period rainfall (where T refers to time).

[0016] Figure 4 Three-dimensional motion diagram of the landslide in the earthquake scenario (where T refers to time).

[0017] Figure 5 A graph showing the relationship between the velocity and time of monitored particles under different scenarios.

[0018] Figure 6 The displacement of monitored particles changes over time under different scenarios. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0020] The landslide motion analysis method based on UAV remote sensing aerial survey and three-dimensional geological modeling of the present invention comprises the following steps: S1. Use the DJI Mavic3E drone with RTK module to obtain high-resolution remote sensing of the landslide hazard investigation area, generate the digital elevation model (DEM), orthophoto and tilt model of the landslide hazard point investigation area, and obtain the terrain conditions and high-resolution terrain data of the landslide hazard point.

[0021] The technical operation process of drones is as follows: (1) Determine the work area on Google Earth, save it as a KMZ file, and import it into the drone.

[0022] (2) Set control points evenly distributed in the area and the drone route. To ensure the smoothness of data processing, two routes with a certain degree of overlap are used to achieve oblique photography when planning the route. The overlap can be set between 50% and 80%.

[0023] (3) Pix4Dmapper software was used to obtain dense point cloud data and generate digital elevation models (DEMs), orthophotos, and oblique models of the survey area.

[0024] S2. The converted digital elevation model of step S1 is imported into Geostudio software, a grid is formed in Geostudio software, and a Geostudio landslide model is established to analyze the sliding surface and damage range of the landslide potential point: In the SEEP / W module of Geostudio software, the seepage field of the slope under different rainfall scenarios is calculated, and the results of this step are inherited. The SLOPE / W module is used for stability analysis to obtain the sliding surface position and stability coefficient of the landslide potential point under different rainfall scenarios. The sliding surface position is the instability and damage range of the landslide, and then the damage range (depth) of the landslide is determined; in the QUAKE / W stress analysis module of Geostudio software, the initial stress of the slope, the initial pore water pressure and the input lateral seismic acceleration data are set as the parent directory, and then the Newmark deformation module is combined to perform slope stability analysis under different earthquake scenarios, and the sliding surface position and stability coefficient of the landslide potential point under different earthquake scenarios are obtained, and then the damage range (depth) of the landslide is determined; The specific steps for analyzing the sliding surface and damage range of landslide potential points in the finite element Geostudio software are as follows: (1) Open Geostudio software, select SEEP / W module, and set the unit time, duration and number of steps; (2) Use ArcGIS to process the high-resolution terrain data obtained in S1 and convert the digital elevation model into projection coordinate data that can be recognized by AutoCAD. Use the boundary command in AutoCAD to generate a dwg file, which is then imported into the SEEP / W module of Geostudio software to generate a Geostudio landslide model, and then meshing is performed; (3) Set the material model, volumetric water content function, and hydraulic conductivity function, and then input them into the drawing material.

[0025] Set and input the initial water level of the landslide and set the input boundary conditions. Add the rainfall boundary conditions to the boundary conditions. Note that you should check the "Potential Seepage Surface Test" to prevent overflow. (4) A new SLOPE / W module is added on the basis of the SEEP / W module to perform stability analysis. After inheriting the above-mentioned seepage analysis results, the sliding surface position and stability coefficient of the landslide potential point in this scenario are calculated. The area above the sliding surface position is the instability and damage range of the landslide, and then the damage range (depth) of the landslide is determined; (5) For earthquake scenarios, after the grid division is completed, the QUAKE / W stress analysis module is used to set the initial stress of the slope, the initial pore water pressure, and the input lateral seismic acceleration data as the parent directory. Then, the Newmark deformation module is combined to perform slope stability analysis under different earthquake scenarios to obtain the sliding surface position and stability coefficient of the landslide hazard point under the scenario. The area above the sliding surface position is the instability and damage range of the landslide, and then the damage range of the landslide under different earthquake scenarios is determined.

[0026] S3, using the high-resolution terrain data of the landslide potential point obtained in S1, a three-dimensional geological model of the landslide is established in the PFC3D software by using ball-wall contact, wherein the sliding surface in the three-dimensional geological model of the landslide is determined by S2, and the sliding bed in the three-dimensional geological model of the landslide is determined based on the damage range of the landslide obtained in S2; Step S2: After obtaining the stability coefficient of the landslide hazard point under different rainfall scenarios and different earthquake scenarios, the stability coefficient is used as the strength reduction coefficient of the rock and soil strength parameter of the landslide, and the rock and soil strength parameter value under natural conditions is multiplied by the corresponding strength reduction coefficient to obtain the strength parameter value under different rainfall scenarios and different earthquake scenarios; the rock and soil strength parameter value under natural conditions is the data determined by experience or experiment when there is no rainfall and earthquake. For example, if the stability coefficient of the landslide hazard point under rainfall conditions calculated by Geostudio is 0.9, then the rock and soil strength parameter under natural conditions (no rainfall, no earthquake, etc.) is multiplied by 0.9 to obtain the rock and soil strength parameter under rainfall conditions.

[0027] The landslide body is discretized into particles, and the discrete element particles in PFC are assigned with the strength parameter values ​​of the corresponding scenarios to obtain the three-dimensional geological model of the landslide under different scenarios. The specific process of step S3 is: (1) Use ArcGIS software to process high-resolution terrain data, import the digital elevation model (DEM) data obtained by drones into ArcGIS, and delineate the sliding bed and sliding body area based on the sliding surface and damage range of the landslide determined by Geostudio software to prepare basic data for subsequent modeling; (2) Import the tif files of the sliding bed and sliding body into GlobalMapper for processing into dem format files that can be recognized by 3Dmax software. After importing them into 3Dmax software, build a 3D model. Export the 3D model into an stl format file that can be recognized by PFC3D software, and then import it into PFC3D to form the final 3D geological model of the landslide; (3) The landslide body is discretized into particles. The discrete element particles in PFC are assigned according to the strength parameter values ​​of the corresponding scenarios. By defining the particle parameters, including particle size, damping coefficient, friction coefficient and some mesoscopic parameters, the damping coefficient, friction coefficient and some mesoscopic parameters are all determined by reducing the stability coefficient, and the particles of the sliding body part under the current scenario are generated.

[0028] S4. Based on the three-dimensional geological model of the landslide under different scenarios obtained in step S3, after setting the initial conditions and boundary conditions of the landslide in the PFC3D software, the landslide is numerically simulated, and the velocity, displacement, and three-dimensional motion range diagram under different scenarios are output, and the three-dimensional motion characteristics of the landslide are analyzed. By analyzing the indicators during its motion process, the danger of the landslide under different rainfall and earthquake conditions (such as motion speed, displacement, impact range, etc.) is reflected, so as to make effective landslide prediction.

[0029] Compare the possible movement range and maximum movement speed of the landslide in different scenarios, so as to compare the landslide hazards in different scenarios.

[0030] (1) Imposing gravity load on the landslide particles and achieving mechanical balance of the landslide particles through the unbalanced force between the restraining particles and the restraining wall, thus avoiding the splashing of landslide particles; (2) Simulate the movement of sliding body particles under the action of gravity, as well as the impact range and accumulation form of the landslide. By setting monitoring particles at different parts of the sliding body, the velocity, displacement, and accumulation form of sliding body particles under different scenarios are output, thereby analyzing the movement process of the landslide.

[0031] Different scenarios in the present invention mainly include changes in rainfall conditions and earthquake conditions, such as rainfall conditions mainly involve rainfall amounts with different return periods, and earthquake conditions involve different earthquake accelerations.

[0032] Since the present invention performs a three-dimensional motion analysis of landslides, it is possible to compare the motion speed, displacement, motion range and accumulation depth of landslide particles under different rainfall scenarios (such as 50-year return period rainfall, 100-year return period rainfall) and different earthquake scenarios. The above indicators can be used as physical quantities to characterize the motion characteristics of landslides, so that the motion characteristics of landslides under different scenarios can be compared.

[0033] The present invention uses Geostudio software to calculate the stability coefficients of different landslide potential points, overcomes the drawback that discrete element PFC software is difficult to realize rainfall infiltration and fluid-solid coupling analysis, establishes Geostudio-PFC coupling analysis of finite element and discrete element, reduces the strength parameters of rock and soil mass by the stability coefficient under different scenarios, and gives accurate strength parameters to the particles in PFC. At the same time, the three-dimensional motion process analysis of landslide potential points is realized by using PFC software.

[0034] Example: The case study of this study is the Zhuangguo Island landslide, which is located in Jizhou District, Tianjin, northern China. A small-scale landslide with a volume of more than 1,000 m was found at the foot of the slope after a heavy rainfall. The vegetation here has been destroyed, but the rest of the slope is still covered with trees. The local civil affairs department has set up a geological disaster early warning point here, but apart from a simple protective net, no professional monitoring equipment has been implemented.

[0035] For the Zhuangguoyu landslide, rainfall is the most important factor that causes the landslide to fail, so it is necessary to analyze extreme rainfall scenarios to predict the potential stability and danger of the landslide in advance. The analysis of the number of rainy days in each month for the extreme rainfall in the study area generated in 1980 and 2017 showed that three consecutive days of rainfall were the most frequent event in the rainy season in the study area. The maximum rainfall for three consecutive days in each month was calculated, and then the relationship between rainfall and return period was calculated using the Matlab program based on the Gumbel distribution.

[0036] The probability density function f(x) and cumulative density function F(x) of the Gumbel distribution are:

[0037]

[0038] Where x refers to the analysis variable. If the analysis is on rainfall conditions, x refers to the rainfall. α is the scale parameter and β is the location parameter. Their relationship can be expressed as:

[0039] Where μ is the mean of the distribution, and the parameters α and β can be estimated by maximum likelihood.

[0040] From the results of extreme rainfall and return period obtained from Gumbel distribution, it can be seen that the rainfall in the return period of 20 years, 50 years and 100 years is 151.5 mm, 184.6 mm and 209.3 mm respectively.

[0041] Step S1: Use the DJI Mavic3E drone with RTK module to obtain high-resolution remote sensing of the landslide. The drone obtains point cloud data through two routes with 83% overlap in heading and 75% overlap in lateral direction. The data are processed by Pix4Dmapper software to generate the digital surface model (DEM), orthophoto and oblique model of the survey area, as shown in Figure 1. Figure 1 As shown, the two lines ABCDE and A'B'C'D'E' in the figure have an overlap of about 75% in this embodiment. ArcGIS is used to process the terrain model, and the digital elevation model (DEM) is converted into projection coordinate data recognizable by AutoCAD. The boundary command is used in AutoCAD to generate a dwg file, which is then imported into the Geostudio software SEEP / W module to generate the Geostudio landslide model. Considering the geometric shape and volume of the slope, the size of the grid is set to 0.5m, thereby determining a total of 6027 nodes and 5866 elements.

[0042] Step S2: The 50-year re-period rainfall is used as the hydraulic boundary condition. Since the on-site engineering survey did not show the groundwater level, the water level line was not set. The seepage field of the slope under the rainfall scenario is calculated in the SEEP / W module of the software, and the results of this step are inherited. The deterministic parameters are input into the SLOPE / W module for stability analysis, and finally the landslide damage range and the stability coefficient under this scenario are obtained, such as Figure 2 shown.

[0043] Step S3: ArcGIS is used to process the terrain data obtained in S1, and the landslide damage range obtained in S2 is determined as the sliding body, and the range without damage is determined as the sliding bed. The above sliding body and sliding bed range are respectively exported into tif format files for importing into GlobalMapper software. The tif file is imported into GlobalMapper for processing into a dem format file, and the file is opened in a 3Dmax file to form a 3D model of the Zhuangguoyu landslide. The file is saved in stl format, and it is imported into PFC3D software to generate a final three-dimensional geological model of the landslide.

[0044] In PFC3D, the ball-wall contact is used to establish the three-dimensional geological model of the landslide. First, the sliding bed is set as the wall, and then the landslide particles are filled in the complex closed surface formed by the upper surface of the landslide body and the sliding bed. The porosity is set to 0.2, the particle radius ranges from 0.4-0.7m, and the bedrock particle size is 0.5-1m. The selected particle size ranges from 0.8m to 1.0m, and a total of 8589 spheres are generated. The ball sphere unit is written into PFC3D, and finally the three-dimensional modeling of the Zhuangguoyu landslide is obtained.

[0045] The stability coefficient of the landslide potential point under the 50-year return period rainfall condition is 0.897, so its strength reduction factor is 0.897. Multiply the rock and soil strength parameter value under the natural scenario by 0.897, which is the rock and soil strength parameter value under the 50-year rainfall return period condition. These parameter values ​​are assigned to particles in the PFC3D software to obtain the three-dimensional geological model of the landslide under the current scenario. The rock and soil strength parameter values ​​include damping coefficient, friction coefficient, cohesion, internal friction angle, etc.

[0046] Step S4: Based on the three-dimensional geological model of the landslide under different scenarios obtained in step S3, the initial conditions and boundary conditions of the landslide are set in the PFC3D software to perform numerical simulation on the landslide, and the three-dimensional movement characteristics of the landslide under different scenarios are analyzed.

[0047] Assign gravity load to the landslide particles, and achieve mechanical balance of the landslide particles through the unbalanced force between the constrained particles and the constrained wall to avoid the splashing of landslide particles. Simulate the movement process of landslide particles under gravity, as well as the impact range and accumulation form of the landslide. In order to better show the three-dimensional movement process of the Zhuangguoyu landslide under rainfall and earthquake scenarios, select T = 5s, 10s, 20s, 30s, 40s, 60s to analyze its movement characteristics, such as Figure 3 and Figure 4 shown.

[0048] In order to more accurately understand the detailed movement of particles in the three-dimensional simulation of the Zhuangguo Island landslide under different scenarios, four monitoring balls were also set up at different positions of the sliding body. The characteristics of the changes in the velocity and time of the monitored particles are as follows: Figure 5 As shown in Figure 2, the particle displacement changes with time. Figure 6 shown.

[0049] Finally, the analysis of the landslide movement simulation results under different scenarios shows that the impact range of landslides under 50-year return period rainfall conditions on surrounding areas is larger than that of earthquake-induced landslides, the particle speed is faster, and the impact range on residential buildings is wider.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0051] Any matters not described in the present invention are applicable to the prior art.

Claims

1. A landslide motion analysis method based on UAV remote sensing aerial survey and three-dimensional geological modeling, characterized in that: The process of the method is: S1. Use drones to obtain high-resolution remote sensing images of the landslide hazard investigation area, generate digital elevation models (DEMs), orthophotos and tilt models of the investigation area, and obtain the terrain conditions and high-resolution terrain data of the landslide hazard points; S2, the digital elevation model of step S1 is converted and imported into Geostudio software to generate Geostudio landslide model, the seepage field of the slope under different rainfall scenarios is calculated in the SEEP / W module of Geostudio software, and the stability analysis is performed using the SLOPE / W module to obtain the sliding surface position and stability coefficient of the landslide potential point under different rainfall scenarios, thereby determining the damage range of the landslide; in the QUAKE / W stress analysis module of Geostudio software, the initial stress of the slope, the initial pore water pressure and the input lateral earthquake acceleration data are set as the parent directory, and then the slope stability analysis under different earthquake scenarios is performed in combination with the Newmark deformation module, thereby obtaining the sliding surface position and stability coefficient of the landslide potential point under the scenario, thereby determining the damage range of the landslide under different earthquake scenarios; S3, using the high-resolution terrain data of the landslide potential point obtained in step S1, a three-dimensional geological model of the landslide is established in the PFC3D software by using ball-wall contact, wherein the sliding surface in the three-dimensional geological model of the landslide is determined by S2, and the sliding bed in the three-dimensional geological model of the landslide is determined based on the damage range of the landslide obtained in S2; Step S2: after obtaining the stability coefficient of the landslide potential point under different rainfall scenarios and different earthquake scenarios, the stability coefficient is used as the strength reduction coefficient of the rock and soil strength parameter of the landslide, and the strength parameter value under different rainfall scenarios and different earthquake scenarios is obtained by multiplying the rock and soil strength parameter value under natural working conditions by the corresponding strength reduction coefficient; The rock and soil strength parameter values ​​under the natural working conditions are the data determined by experience or experiment when there is no rainfall and earthquake; The landslide body is discretized into particles, and the discrete element particles in PFC are assigned with the strength parameter values ​​of the corresponding scenarios to obtain the three-dimensional geological model of the landslide under different scenarios. S4. Based on the three-dimensional geological model of the landslide under different scenarios obtained in step S3, the initial conditions and boundary conditions of the landslide are set in the PFC3D software to perform numerical simulation on the landslide, and the velocity, displacement, and three-dimensional motion range diagram under different scenarios are output to analyze the three-dimensional motion characteristics of the landslide under different scenarios.

2. The method according to claim 1, characterized in that The three-dimensional movement characteristics of landslides under different scenarios are analyzed, including the movement speed, displacement, movement range and accumulation depth of landslide particles, and the possible movement range and maximum movement speed of landslides under different scenarios are compared, so as to compare the landslide hazards under different scenarios.

3. The method according to claim 1, characterized in that The rock and soil strength parameter values ​​include damping coefficient, friction coefficient, cohesion and internal friction angle.

4. The method according to claim 1, characterized in that: The drone is a DJI Mavic 3E drone equipped with an RTK module. When planning the route of the drone, two routes with a certain degree of overlap are used to achieve oblique photography, and the overlap is 50-80%.

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