Risk assessment method for bank geological disasters based on interaction between landslide movement and surge propagation

Abstract

This invention belongs to the field of geological disaster prevention and control technology, and discloses a method for assessing reservoir bank geological disaster risk based on the interaction between landslide movement and surge propagation. The method includes acquiring geological data of the target reservoir bank, quantitatively calculating the stability of the reservoir bank using the Morgensstein-Platz method to obtain a first stability assessment result; quantitatively calculating the surge risk of the reservoir bank using the Pan Jiazheng method based on the geological data to obtain a first surge prediction result; and finally, obtaining the reservoir bank geological disaster risk assessment result. This invention establishes a risk-oriented hierarchical standard, constructs a multi-level stability evaluation system, and comprehensively utilizes qualitative analysis of geological conditions, quantitative calculation of rigid body limit equilibrium, and three-dimensional numerical simulation analysis, significantly improving the reliability of the evaluation results. It realizes the integrated coupled simulation of landslide movement and surge propagation, forming a complete technical closed loop for the reservoir bank geological disaster risk assessment method.

Description

Technical Field

[0001] This invention belongs to the field of geological disaster prevention and control technology, specifically relating to a reservoir bank geological disaster risk assessment method based on the interaction between landslide movement and surge propagation. Background Technology

[0002] Water conservancy and hydropower projects are important infrastructure. While conventional hydropower stations provide comprehensive benefits such as flood control, power generation, water supply, and ecological regulation, geological safety issues, especially slope-related geological hazards, within their reservoir areas and watersheds have always been a core risk that needs to be focused on and controlled during the construction and long-term operation of these projects.

[0003] Studies have revealed that geological hazards in the watershed and reservoir area of ​​hydropower stations are mainly slope-related hazards such as landslides, collapses, and deformable bodies. These hazards are characterized by their wide distribution, high degree of concealment, complex inducing factors, and severe consequences. After the hydropower station begins operation, the repeated rise and fall of reservoir water, infiltration and softening, wave erosion, and changes in hydrostatic and seepage pressures significantly alter the physical and mechanical properties and stress state of the riverbank soil and rock. This causes previously stable or basically stable natural slopes to experience accelerated deformation, strength deterioration, and even overall instability.

[0004] For reservoir banks near the dam, the instability and sliding caused by the aforementioned geological disasters can not only damage the bank slopes and bury reservoir facilities, but also potentially generate significant swells. These swells, propagating within the reservoir, will directly threaten the lives and property of the dam, navigation structures, and residents in the surrounding area. This is especially true for hydropower stations located in deep river valleys in the west, where the valleys are narrow, the banks are steep, and the water is deep. Once a geological disaster occurs, the initial height and propagation energy of the swells are more pronounced after the unstable body enters the reservoir, posing a more severe potential threat to the key engineering projects.

[0005] Therefore, there is an urgent need to establish a systematic technical method that integrates stability evaluation, instability surge prediction and risk assessment for major geological disasters near dams and reservoir banks. This method will accurately determine the stability of the disaster body, quantitatively assess the surge risk that may occur after its instability, and propose effective risk prevention and control measures accordingly. Summary of the Invention

[0006] To address or partially address the problems in existing technologies, this invention provides a method for assessing reservoir bank geological hazard risks based on the interaction between landslide movement and surge propagation, comprising the following steps: Obtain geological data of the target reservoir bank, wherein the geological data includes at least one or more of the following: topographic data, material composition data, and slope boundary data; Based on the geological data, the stability of the target reservoir bank was quantitatively calculated using the Morgenstern-Price method to obtain the first stability assessment result; Based on the geological data, the Pan Jiazheng method was used to quantitatively calculate the surge risk of the target reservoir bank, and the first surge prediction result was obtained. Based on the first stability assessment result and the first surge prediction result, a risk assessment of geological hazards on the target reservoir bank is conducted to obtain the reservoir bank geological hazard risk assessment result.

[0007] In a further preferred embodiment, the method further includes: A three-dimensional numerical analysis model was constructed using the three-dimensional finite difference software FLAC-3D. Based on the geological data, the three-dimensional numerical analysis model is used to simulate the elastoplastic values ​​of the target reservoir bank, thereby quantitatively calculating the stability of the target reservoir bank and obtaining a second stability assessment result; and / or The stability comparison results are obtained by comparing and analyzing the first stability assessment results with the second stability assessment results.

[0008] In a further preferred embodiment, the method further includes: The Sassa model was written using the COMCOT open-source program to construct a numerical model of landslide surge. Based on the geological data, the landslide surge numerical model is used to simulate the surge conditions of the target reservoir bank, resulting in a second surge prediction result. The simulation of the surge conditions of the target reservoir bank includes at least one or more of the following: landslide movement, shovel entrapment, hydroplaning interaction, and surge generation and propagation; and / or By comparing and analyzing the first surge prediction result with the second surge prediction result, a surge risk comparison result is obtained.

[0009] In a further preferred embodiment, the method further includes: Obtain the geometric morphological data of the downstream water-retaining structures of the target reservoir; Based on the geometric morphology data, the landslide surge wave numerical model is used to simulate the surge wave uplift effect, and a second surge wave prediction result is obtained based on the surge wave uplift effect.

[0010] In a further preferred embodiment, the method further includes: Obtain overall geological data for the area to be assessed; Based on the overall geological data, the corresponding slope grades are determined for multiple reservoir banks in the area to be evaluated, and the safety factor corresponding to the slope grade is obtained based on the slope grade. Based on the safety factor and the preset safety factor threshold, the target reservoir bank in the area to be evaluated is obtained.

[0011] In a further preferred embodiment, the slope grade is calculated from one or more of the following: engineering grade data, building grade data, and slope location data.

[0012] A further preferred technical solution is that the landslide surge numerical model includes: The landslide motion control equations simulate the movement of a landslide body on and / or underwater. The landslide motion control equations include gravity parameters, lateral pressure parameters, base friction parameters, and, when moving underwater, water drag force parameters and buoyancy parameters. The surge control equation simulates the generation and propagation process of surges. The surge control equation includes parameters of water body base friction, lateral pressure, and drag force of landslide on water. The landslide motion control equation and the surge control equation are solved discretely using the finite difference method, and the coupling of landslide motion and water motion is achieved in each calculation step through the relationship between action and reaction forces.

[0013] In a further preferred embodiment, the landslide motion control equations include surface motion control equations and underwater motion control equations; The control equations for waterborne motion are expressed as follows:

[0014]

[0015]

[0016] in: The thickness of the landslide; , landslides , Flux in the direction; The erosion rate of the landslide; It is the acceleration due to gravity; , The landslide bottom and flat, Angle between planes Geometric morphology factor; This represents the lateral pressure coefficient of the landslide. , The internal friction angle of the landslide; , , , They are respectively Hydrodynamic correction factor or geometric projection factor for direction. , , landslides , , velocity in the direction; For landslide cohesion; The effective density of the landslide; This is the standard notation for partial derivatives, where and For the temporal variation of landslide dynamics, Additional resistance caused by terrain undulations; landslide erosion rate The calculation equation for the basal erosion rate proposed by Fraccarollo and Capart is as follows:

[0017] In the formula: This represents the elevation of the landslide erosion surface. This represents the shear stress of the sliding body at the sliding surface. The shear strength of the eroded layer; The density of the eroded layer; The velocity of the sliding body; For time; The underwater motion control equation is expressed as follows:

[0018]

[0019]

[0020] In the formula, The drag coefficient of the water body; , Geometric morphology factor Respectively, water bodies or reference objects are in The speed of movement in the direction, , The top surface of the landslide and flat, Angle between planes; The surge control equation is expressed as follows:

[0021]

[0022]

[0023] In the formula: The amplitude of the swell; , respectively surging waves , Flux in the direction; For water depth; This is the Manning coefficient; This is the density of water.

[0024] In a further preferred embodiment, the method further includes: Based on the results of the reservoir bank geological disaster risk assessment, risk prevention and control measures are proposed, including one or more of the following: monitoring and early warning, earthmoving and load reduction, anti-slide pile reinforcement, or drainage engineering.

[0025] A reservoir bank geological hazard risk assessment system based on the interaction between landslide movement and surge propagation includes: The reservoir bank geological data acquisition module is used to acquire the address data of the target reservoir bank. The geological data includes at least one or more of the following: topographic data, material composition data, and slope boundary data. The reservoir bank stability quantitative calculation module uses the Morgenstern-Price method based on the geological data to quantitatively calculate the stability of the target reservoir bank and obtain the first stability assessment result. The reservoir bank surge risk quantitative calculation module uses the Pan Jiazheng method based on the geological data to quantitatively calculate the surge risk of the target reservoir bank and obtain the first surge prediction result. The reservoir bank geological hazard risk assessment module, based on the first stability assessment result and the first surge prediction result, is used to conduct a risk assessment of geological hazards on the target reservoir bank and obtain the reservoir bank geological hazard risk assessment result.

[0026] Compared with existing technologies, the present invention provides a reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation, which has the following advantages: (1) A risk-oriented classification standard was established. This invention establishes a differentiated slope classification and safety control standard system based on whether the instability of near-dam reservoir bank geological disasters directly endangers the safety of key structures, and whether the resulting surge waves endanger the safety of key structures. For major geological disasters that do not directly endanger the safety of key structures after instability, but whose surge waves may endanger the safety of key structures, they are classified as Class B, Grade I slopes, and corresponding design safety factors are set. This classification and calibration method incorporates surge wave risk into the safety control standard, breaking through the limitation of traditional specifications that only focus on the stability of the slope itself.

[0027] (2) A multi-level stability evaluation system was constructed. This invention integrates qualitative analysis of geological conditions, quantitative calculation of rigid body limit equilibrium, and three-dimensional numerical simulation analysis to form a complementary stability evaluation system. Qualitative analysis provides a macroscopic understanding from the perspectives of boundary conditions, material composition, and deformation and failure mechanisms; the limit equilibrium method, based on the Morgenstern-Price method, performs two-dimensional rigid body limit equilibrium analysis, providing a safety factor that meets regulatory requirements; the three-dimensional numerical analysis, based on elastoplastic theory, uses FLAC-3D to simulate the stress field, displacement field, and plastic zone distribution characteristics of geological hazards under different working conditions. The three methods mutually verify each other, significantly improving the reliability of the evaluation results.

[0028] (3) Integrated coupled simulation of landslide movement and surge propagation was realized. This invention overcomes the limitations of traditional methods that artificially separate landslide movement from the generation and propagation of surge waves, establishing an integrated numerical model of landslides and surge waves. This model discretizes and solves the landslide movement control equations and surge wave control equations using the finite difference method, and achieves bidirectional coupling between landslide movement and water movement in each calculation step through the relationship between action and reaction forces. The landslide movement control equations include terms related to gravity, lateral pressure, base friction, water drag, and buoyancy; the surge wave control equations include terms related to base friction, lateral pressure, and the drag effect of the landslide on the water. This model can realistically simulate the entire process of a landslide from initiation, movement, entry into water, to the generation and propagation of surge waves. Furthermore, this invention provides a differentiated technical path selection mechanism for geological hazards with varying levels of data completeness, balancing the scientific rigor of the assessment with the feasibility of engineering implementation.

[0029] (4) A closed-loop technology system covering the entire process of "evaluation-prediction-prevention" has been formed. This invention establishes a complete technical process, from determining slope grade and safety control standards, evaluating geological hazard stability, quantitatively calculating instability surge waves, to suggesting risk prevention and control measures. Through this invention, the stability state of geological hazards can be scientifically assessed, the potential surge wave height after instability and its impact on key projects can be accurately calculated, and targeted prevention and control measures such as monitoring and early warning, earthmoving and load reduction, and anti-slide pile reinforcement can be proposed to effectively avoid the adverse effects of geological hazards and their secondary surge wave disasters on the long-term safe operation of hydropower projects. Attached Figure Description

[0030] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a diagram illustrating the core steps of the method of the present invention; Figure 3 This is a plan view of the collapsed accumulation body according to an embodiment of the present invention; Figure 4 The collapsed accumulation body in the embodiment of the present invention is respectively along Figure 3 Cross-sectional views of b-b' and c-c' in the middle; Figure 5 This is a numerical simulation model diagram of the collapsed accumulation body according to an embodiment of the present invention; Figure 6 This is a stability partitioning diagram based on calculation results from an embodiment of the present invention; Figure 7 This is a schematic diagram of the nearshore surge rise height according to an embodiment of the present invention. Detailed Implementation

[0031] The following will clearly and completely describe the concept, specific steps, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be particularly noted that the described embodiments are merely some embodiments of the present invention, and not all embodiments. Other embodiments obtained by other personnel skilled in the art based on the embodiments of the present invention without making creative contributions are all within the protection scope of the present invention.

[0032] This implementation provides a reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation, combined with... Figure 1 The flowchart of the method of the present invention includes the following steps: Obtain geological data of the target reservoir bank, wherein the geological data includes at least one or more of the following: topographic data, material composition data, and slope boundary data.

[0033] Based on the geological data, the stability of the target reservoir bank was quantitatively calculated using the Morgenstern-Price method to obtain the first stability assessment result; Based on the geological data, the Pan Jiazheng method was used to quantitatively calculate the surge risk of the target reservoir bank, and the first surge prediction result was obtained. Based on the first stability assessment result and the first surge prediction result, a risk assessment of geological hazards on the target reservoir bank is conducted to obtain the reservoir bank geological hazard risk assessment result.

[0034] In this embodiment, a reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation further includes: A three-dimensional numerical analysis model is constructed using the three-dimensional finite difference software FLAC-3D. Based on the geological data, the three-dimensional numerical analysis model is used to simulate the elastic-plastic properties of the target reservoir bank to quantitatively calculate the stability of the target reservoir bank and obtain a second stability assessment result; and / or the first stability assessment result is compared and analyzed with the second stability assessment result to obtain a stability comparison result.

[0035] In this embodiment, a reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation further includes: The Sassa model was written using the COMCOT open-source program to construct a landslide surge numerical model. Based on the geological data, the surge situation of the target reservoir bank was simulated using the landslide surge numerical model to obtain a second surge prediction result. The simulation of the surge situation of the target reservoir bank includes at least one or more of the following: landslide movement, scouring and scraping, water-sliding interaction, and surge generation and propagation. And / or the first surge prediction result and the second surge prediction result were compared and analyzed to obtain a surge risk comparison result. The landslide surge numerical model includes: landslide motion control equations, simulating the movement of the landslide body above and / or underwater, wherein the landslide motion control equations include gravity parameters, lateral pressure parameters, base friction parameters, and, when moving underwater, water drag force parameters and buoyancy parameters; and surge control equations, simulating the generation and propagation of surges, wherein the surge control equations include water base friction parameters, lateral pressure parameters, and drag force parameters of the landslide body on the water body; wherein the landslide motion control equations and the surge control equations are discretely solved using the finite difference method, and the coupling of landslide motion and water motion is achieved in each calculation step through the relationship between action and reaction forces.

[0036] The governing equations for landslide motion include the governing equations for surface motion and the governing equations for underwater motion; the governing equations for surface motion are expressed as follows:

[0037]

[0038]

[0039] in: The thickness of the landslide; , landslides , Flux in the direction; The erosion rate of the landslide; It is the acceleration due to gravity; , The landslide bottom and flat, Angle between planes Geometric morphology factor; This represents the lateral pressure coefficient of the landslide. , The internal friction angle of the landslide; , , , They are respectively Hydrodynamic correction factor or geometric projection factor for direction. , , landslides , , velocity in the direction; For landslide cohesion; The effective density of the landslide; This is the standard notation for partial derivatives, where and For the temporal variation of landslide dynamics, Additional resistance caused by terrain undulations.

[0040] landslide erosion rate The calculation equation for the basal erosion rate proposed by Fraccarollo and Capart is as follows:

[0041] In the formula: This represents the elevation of the landslide erosion surface. This represents the shear stress of the sliding body at the sliding surface. The shear strength of the eroded layer; The density of the eroded layer; The velocity of the sliding body; For time.

[0042] Furthermore, the underwater motion control equations are expressed as follows:

[0043]

[0044]

[0045] In the formula, The drag coefficient of the water body; , Geometric morphology factor Respectively, water bodies or reference objects are in The speed of movement in the direction, , The top surface of the landslide and flat, Angle between two planes.

[0046] The surge control equation is expressed as follows:

[0047]

[0048]

[0049] In the formula: The amplitude of the swell; , respectively surging waves , Flux in the direction; For water depth; This is the Manning coefficient; This is the density of water.

[0050] In this embodiment, a reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation further includes: Obtain the geometric morphology data of the downstream water-retaining structure of the target reservoir bank; simulate the surge height effect of the surge using the landslide surge numerical model based on the geometric morphology data, and obtain the second surge prediction result based on the surge height effect.

[0051] In this embodiment, a reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation further includes: Obtain overall geological data of the area to be evaluated; based on the overall geological data, delineate corresponding slope grades for multiple reservoir banks in the area to be evaluated, and obtain the safety factor corresponding to each slope grade; based on the safety factor and a preset safety factor threshold, obtain the target reservoir bank in the area to be evaluated. The slope grade is calculated from one or more of the following: engineering grade data, building grade data, and slope location data.

[0052] In this embodiment, a reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation further includes: Based on the results of the reservoir bank geological disaster risk assessment, risk prevention and control measures are proposed, including one or more of the following: monitoring and early warning, earthmoving and load reduction, anti-slide pile reinforcement, or drainage engineering.

[0053] This embodiment also provides an integrated reservoir bank geological hazard risk assessment system based on the interaction between landslide movement and surge propagation, including: The reservoir bank geological data acquisition module is used to acquire the geological data of the target reservoir bank, which includes at least one or more of the following: topographic data, material composition data, and slope boundary data. The reservoir bank stability quantitative calculation module uses the Morgenstern-Price method based on the geological data to quantitatively calculate the stability of the target reservoir bank, obtaining a first stability assessment result. The reservoir bank surge risk quantitative calculation module uses the Pan Jiazheng method based on the geological data to quantitatively calculate the surge risk of the target reservoir bank, obtaining a first surge prediction result. The reservoir bank geological hazard risk assessment module uses the first stability assessment result and the first surge prediction result to conduct a geological hazard risk assessment of the target reservoir bank, obtaining a reservoir bank geological hazard risk assessment result.

[0054] In this embodiment, preferably, the slope grade of the target reservoir bank geological hazard is determined, and stability design safety control standards are set according to the slope grade under persistent, transient, and accidental working conditions. The slope grade is determined based on the hydropower engineering slope design specifications, combined with the grade of the key project to which the target reservoir bank geological hazard belongs, the level of the structure, its location, and the degree of instability hazard.

[0055] The geological conditions of the target reservoir bank geological hazards were analyzed, and based on these conditions, a combination of qualitative analysis and quantitative calculation was used to evaluate the stability of the target reservoir bank geological hazards and obtain stability evaluation results. The quantitative calculation included at least a two-dimensional rigid body limit equilibrium analysis using the limit equilibrium method. The quantitative calculation also included three-dimensional numerical analysis. The three-dimensional numerical analysis applied elastoplastic theory to establish a three-dimensional geological model including the target reservoir bank geological hazards and its underlying bedrock. The stress field, displacement field, and plastic zone distribution characteristics of the target reservoir bank geological hazards under natural, water storage, rainstorm, and seismic conditions were analyzed to evaluate the stability of the target reservoir bank geological hazards. The qualitative analysis included analyzing the boundary conditions, material composition and structure, geological structure, deformation and failure mechanisms, and potential instability modes of the target reservoir bank geological hazards to obtain macroscopic judgment results on the stability of the target reservoir bank geological hazards.

[0056] When the stability evaluation results indicate that the target reservoir bank geological disaster has the risk of instability, the landslide-surge integrated numerical model is used to calculate the surge risk generated after the target reservoir bank geological disaster becomes unstable, and the surge calculation results are obtained; wherein, the landslide-surge integrated numerical model couples the landslide movement process with the surge generation and propagation process in the same model.

[0057] In this embodiment, preferably, the aforementioned quantitative calculation and surge risk calculation are selected based on whether the exploration data and geological survey data of the target reservoir bank geological disaster are sufficient to establish a three-dimensional geological model: when a three-dimensional geological model can be established, the quantitative calculation includes limit equilibrium analysis and three-dimensional numerical analysis, and the surge risk calculation includes the Pan Jiazheng method and the integrated numerical model of landslide and surge. When a three-dimensional geological model cannot be established, the quantitative calculation only uses limit equilibrium analysis, and the surge risk calculation only uses the Pan Jiazheng method. In this embodiment, the calculation also includes using the Pan Jiazheng method to calculate the surge risk generated after the instability of the target reservoir bank geological disaster, obtaining the surge calculation result of the Pan Jiazheng method; and comparing and analyzing the surge calculation result of the Pan Jiazheng method with the calculation result of the integrated numerical model of landslide and surge to obtain the surge risk comparison analysis result.

[0058] This embodiment provides a reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation. Taking the collapsed accumulation body near the dam of a conventional hydropower project as the object, the method described in this invention is applied to conduct stability evaluation, instability surge prediction and risk assessment.

[0059] See also Figure 1 Flowchart of the method of the present invention and Figure 2 The core steps of the method of this invention are shown in the diagram. This embodiment of a reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation mainly includes the following steps: I. Determination of Slope Grade and Safety Control Standards The selected bank slope in this embodiment is located within the reservoir area, on the left bank of a river, approximately 2 km from the nearest dam site and 4.2 km from the dam site by its centerline. According to the "Code for Design of Slopes in Hydropower Projects" (NB / T 10512-2021), the slope is classified based on the level of the key project, the structure level, the location of the geological hazard, and the degree of instability, thus determining the slope grade of the target reservoir bank's geological hazards. In this embodiment, it can be divided into three categories (A, B, and C) and three levels (I, II, and III), as shown in Table 1 below. Table 1. Classification and Grade of Slopes in Water Conservancy and Hydropower Projects

[0060] The collapsed accumulation body selected in this embodiment is located within the reservoir area. Its instability will not directly endanger the safety of the key structures, but the resulting surge waves may endanger the safety of structures such as the dam. Therefore, it is classified as a Class B, Grade I slope. After determining the slope grade of the target reservoir bank geological hazard, according to the specifications and slope category and grade, stability design safety control standards are set for its stability under persistent, transient, and accidental working conditions, with design safety factors of 1.15, 1.05, and 1.05, respectively.

[0061] Considering the selected landslide debris body, whose leading edge elevation is 2535m lower than the normal reservoir water level, the following calculation conditions are determined: Condition 1 (Persistent Condition): Natural condition, which is the water level under natural river conditions, taking into account the basic load of self-weight; Operating Condition 2 (Persistent Operating Condition): Normal operating condition, with the reservoir filled to the normal water level of 2535m, taking into account the basic load of self-weight; Condition 3 (Short-term condition): Heavy rain condition, based on condition 2, taking into account the reduction in soil and rock strength and groundwater pressure; Case 4 (accidental case): seismic case, with seismic load superimposed on Case 2, and the horizontal peak acceleration is calculated as 25% of 0.2g.

[0062] This embodiment establishes a risk-oriented classification standard by classifying slopes and setting safety control standards as described above. For major geological hazards that do not directly endanger the safety of the dam after instability but may be endangered by swells, they are classified as Class B, Grade I slopes and corresponding safety factors are set. Swell risk is incorporated into the safety control standards, breaking through the limitation of traditional specifications that only focus on the stability of the slope itself.

[0063] II. Geological Condition Analysis and Qualitative Stability Evaluation (I) Qualitative Analysis

[0064] Based on geological conditions, a combination of qualitative analysis and quantitative calculation is used to evaluate the stability of geological hazards on the target reservoir bank and obtain stability evaluation results. The quantitative calculation includes at least a two-dimensional rigid body limit equilibrium analysis using the limit equilibrium method. The qualitative analysis includes analyzing the boundary conditions, material composition and structure, geological structure, deformation and failure mechanisms, and potential instability modes of the collapsed deposit, obtaining a macroscopic assessment of the stability of the geological hazards on the target reservoir bank.

[0065] The geological conditions of the target reservoir bank geological hazard are analyzed. The plan view of the selected landslide deposit in this embodiment is as follows. Figure 3 As shown, the planar shape is mushroom-shaped with clear boundaries. Bedrock is exposed at the rear and sides, and the front edge is also bounded by the exposed bedrock. Based on topographic contour lines and the elevation isopleths of the bedrock interface, the volume of the collapsed deposit is calculated to be 390 × 10⁻⁶. 4 m³.

[0066] Field investigations show that the material composition of the deposit is mainly composed of gravel with a particle size ranging from 2 to 20 cm, accounting for 70 to 80% of the entire deposit. Except for the top few meters which have a loose structure, the particles in other parts of the deposit are tightly interlocked and filled, with no obvious voids, and the deposit is in a medium to dense state.

[0067] Qualitative analysis suggests that, in its natural state, the deposit is mainly composed of gravel with tightly interlocked particles, resulting in a generally stable state. However, after water is impounded, the front edge of the deposit is mostly below the reservoir water level, subject to the long-term effects of periodic reservoir water changes and erosion. This could lead to a deterioration in its mechanical properties and a significant risk of deformation and slippage.

[0068] (ii) Quantitative Calculation Rigid body limit equilibrium analysis was performed on typical geological profiles of the accumulation body (such as...). Figure 4 As shown, the collapsed accumulation body in this embodiment is arranged along... Figure 3 (Sectional diagrams of b-b' and c-c' are shown). Two-dimensional rigid body limit equilibrium analysis was performed using the Morgenstern-Price (MP) method, with Geostudio software as the calculation program. The underlying bedrock was considered as an impenetrable stratum, and the most dangerous potential slip surface was determined using an automatic search method.

[0069] The calculation parameters were determined through a combination of on-site large shear tests, engineering experience analogies, and qualitative analysis and back-calculation under natural conditions. Under natural conditions, the bulk density was taken as 21 kN / m³, the internal friction angle as 32°, and the cohesion as 35 kPa; under saturated conditions, the bulk density was taken as 22 kN / m³, the internal friction angle as 30°, and the cohesion as 20 kPa. For heavy rain conditions, the bulk density was appropriately increased (taken as 21.5 kN / m³) for calculation.

[0070] The calculation results show that the stability coefficient is 1.581 under natural conditions, 1.413 under normal operating conditions, 1.406 under rainstorm conditions, and 1.237 under earthquake conditions, all of which meet the design safety factors required by the specifications. Quantitative calculations also include three-dimensional numerical analysis. This analysis applies elastoplastic theory to establish a three-dimensional geological model encompassing the collapsed deposit and its underlying bedrock. The model assesses stability by analyzing the stress field, displacement field, and plastic zone distribution characteristics under natural, water-retaining, rainstorm, and seismic conditions. Based on macroscopic geological assessments and limit equilibrium analysis, three-dimensional numerical simulations are performed using FLAC-3D finite difference software. The calculation model includes the collapsed deposit and its underlying bedrock, such as... Figure 5 The numerical simulation model of the collapsed accumulation body in this embodiment of the invention is shown in the figure. The bottom boundary elevation of the model is 2252m, the top boundary elevation is 2832m, and a total of 628229 grid elements are divided. The accumulation body is considered as an elastoplastic material, and the failure criterion adopts the Mohr-Coulomb strength criterion; the bedrock is considered as an elastic material.

[0071] This embodiment is specifically divided into three cases: (1) Simulation results under natural conditions The system converged after 8186 iterations. The stress field characteristics exhibited those of a valley stress field clearly controlled by gravity. The maximum principal stress was nearly vertical within the model, deflecting as it approached the valley slope. Shear strain increments were mainly concentrated at the boundaries of the accumulation body and at the contact surface between the accumulation body and the bedrock. There were no obvious shear strain concentration zones within the accumulation body. The maximum shear strain increment was 5.425 × 10⁻⁶. - ². Plastic zone analysis shows that the accumulator has no obvious tensile yield zone, while the shear yield zone is distributed from the upper-middle left side of the accumulator to the leading edge of the left boundary, and is not completely continuous. Displacement field analysis indicates that the displacement direction of the accumulator is generally downward and towards the left gully, with a maximum displacement of about 60 cm, located in the upper-middle part of the accumulator.

[0072] (2) Simulation results under normal reservoir operation conditions Compared to the natural state, the stress values ​​of the accretion mass increased, and the range of tensile stress at the trailing edge decreased significantly. The increase in shear strain was mainly concentrated at the base-overburden interface and the boundary of the accretion mass below the reservoir water level, with a significantly increased range, but not completely continuous. The maximum shear strain increment at the bb′ profile increased from 2.032 × 10⁻⁶ in the natural state. - ² Increased to 2.442 × 10 - ², the maximum shear strain increment in the cc′ section is 3.595 × 10 . - ² Increased to 4.710 × 10 - ², dd′ profile is 2.958×10 - ² Increased to 3.535×10 - ². The distribution range of the plastic zone has significantly expanded, widely distributed in the front part of the accumulation body and around the boundary. The distribution of the plastic zone at the front edge of the cross-section is relatively continuous, and local sliding may occur. The maximum displacement has increased from 60 cm in the natural state to 72 cm.

[0073] (3) Simulation results under seismic conditions Under seismic conditions, the concentrated zone of shear strain increment extends towards the leading edge of the deposit, and its extent increases significantly. The maximum shear strain increment at the cc′ profile increases to 1.838 × 10⁻⁶. - ¹, the dd′ profile increased to 2.046 × 10⁻⁶. - ¹, the concentrated shear strain zones in the cc′ and dd′ profiles basically extend from the top to the bottom of the slope. The distribution range of the plastic zone further expands, with the tensile yield zone mainly distributed at the rear edge of the accumulation body, and the shear yield zone widely distributed in the middle and lower parts of the accumulation body and around the boundary. The cc′ and dd′ profiles form a continuous shear plastic zone. The maximum displacement increases to 3.38m.

[0074] In summary, based on the limit equilibrium method, three-dimensional numerical analysis results, and topographic features, this embodiment can be considered that the right bank slope of the longitudinal groove in the middle of the collapsed deposit is stable, while the left bank slope has poor stability or is even unstable. Figure 6 As shown in the stability zoning diagram based on the calculation results of this embodiment of the invention, large-scale instability may occur under seismic conditions.

[0075] This embodiment comprehensively utilizes qualitative analysis of geological conditions, quantitative calculation of rigid body limit equilibrium (MP method), and three-dimensional numerical simulation analysis (FLAC-3D) to form a complementary multi-level stability evaluation system. The three methods mutually verify each other, significantly improving the reliability of the evaluation results.

[0076] III. Instability Surge Calculation When the stability assessment results indicate that the collapsed deposit is at risk of instability, surge wave calculations are performed based on the overall instability mode of the deposit, according to the stability assessment results. The surge wave risk after the deposit's instability under a normal water level of 2535m is calculated using both the Pan Jiazheng method and the integrated landslide-surge wave numerical model, respectively, yielding the surge wave calculation results. The integrated landslide-surge wave numerical model couples the landslide movement process with the surge wave generation and propagation process within the same model.

[0077] (I) Calculation using the Pan Jiazheng method The dd′ profile was used as the calculation profile, consisting of 33 segments, each 10m wide, with a mass density of 2200kg / m³. The mass at the water inlet was 350m wide, with an average thickness of 21m and an average dip angle of 30°. The water depth was 120m, the river channel width was 300m, and the dam site distance was 4250m. Considering the uncertainty of the dynamic internal friction angle, calculations were performed using angles of 27°, 28°, and 29°, with cohesion taken as 0kPa.

[0078] Calculation results show that: at an internal friction angle of 27°, the inflow velocity is 7.99 m / s, the initial wave height is 4.89 m, and the wave height at the dam site is 0.14 m; at an internal friction angle of 28°, the inflow velocity is 6.62 m / s, the initial wave height is 4.05 m, and the wave height at the dam site is 0.12 m; at an internal friction angle of 29°, the inflow velocity is 5.41 m / s, the initial wave height is 3.31 m, and the wave height at the dam site is 0.10 m. Under all three parameters, the wave height at the dam site is less than 0.15 m, having minimal impact on the key project.

[0079] (II) Calculation of integrated numerical model for landslide and surge An integrated numerical model of landslide and surge was established. The computational domain was divided into 2150×1167 differential grids on the XOY plane, with an actual grid size of 6m×6m and a computational range of 7km×12.9km. The density of the accumulated mass was taken as 2200kg / m³, the cohesion as 0kPa, and the internal friction angles as 27°, 28°, and 29°, respectively. The density of water was taken as 1000kg / m³, the Manning coefficient as 0.03, and the viscosity coefficient as 0.1.

[0080] The integrated numerical model of landslide and surge includes landslide motion control equations and surge control equations. The landslide motion control equations simulate the movement of the landslide mass above and / or underwater, including gravity parameters, lateral pressure parameters, base friction parameters, and, when moving underwater, parameters including water drag force and buoyancy parameters. The surge control equations simulate the generation and propagation of surges, including water base friction parameters, lateral pressure parameters, and parameters of the drag effect of the landslide mass on the water. Both the landslide motion control equations and the surge control equations are solved discretly using the finite difference method, and the coupling of landslide motion and water motion is achieved in each calculation step through the relationship between action and reaction forces.

[0081] The landslide motion control equations include above-water motion control equations and underwater motion control equations; The control equations for waterborne motion are expressed as follows:

[0082]

[0083]

[0084] In the formula: The thickness of the landslide; , landslides , Flux in the direction; The erosion rate of the landslide; It is the acceleration due to gravity; , The landslide bottom and flat, Angle between planes Geometric morphology factor; This represents the lateral pressure coefficient of the landslide. , The internal friction angle of the landslide; , , , They are respectively Hydrodynamic correction factor or geometric projection factor for direction. , , landslides , , velocity in the direction; For landslide cohesion; The effective density of the landslide; This is the standard notation for partial derivatives, where and For the temporal variation of landslide dynamics, Additional resistance caused by terrain undulations; landslide erosion rate The calculation equation for the basal erosion rate proposed by Fraccarollo and Capart is as follows:

[0085] In the formula: This represents the elevation of the landslide erosion surface. This represents the shear stress of the sliding body at the sliding surface. The shear strength of the eroded layer; The density of the eroded layer; The velocity of the sliding body; The underwater motion control equations are expressed as follows:

[0086]

[0087]

[0088] In the formula, The drag coefficient of the water body; , Geometric morphology factor Respectively, water bodies or reference objects are in The speed of movement in the direction, , The top surface of the landslide and flat, Angle between planes; The surge control equation is expressed as follows:

[0089]

[0090]

[0091] In the formula: The amplitude of the swell; , respectively surging waves , Flux in the direction; For water depth; This is the Manning coefficient; This is the density of water.

[0092] The integrated numerical model of landslide and surge used in this embodiment solves the landslide motion control equation and surge control equation discretizedly using the finite difference method. In each calculation time step, the action and reaction forces are used to achieve bidirectional coupling between landslide motion and water motion. This model can realistically simulate the entire process of landslide from initiation, motion, water entry to surge generation and propagation, avoiding the technical limitations of traditional methods that artificially separate landslide motion from surge generation and propagation.

[0093] Taking the simulation results with an internal friction angle of 27° as an example: the accumulation body begins to move at 10s with a maximum sliding speed of 11.8m / s; at 15s, the leading edge of the accumulation body moves to below the 2400m elevation with a maximum thickness of 60.2m; at 25s, the accumulation body moves to the bottom of the river channel with an accumulation thickness of about 7m in the river channel; at 39s, the movement stops with an accumulation thickness of about 30m in the river channel.

[0094] Surge simulation results: At 10s, a propagating surge is formed in the river channel with a maximum amplitude of 5.0m; at 20s, the surge propagates to the opposite bank with a surge amplitude of 5.0m; at 150s, the surge propagates to the dam site with a maximum wave height of 2.0m; at 760s, the surge propagates to the upstream boundary, and the water surface is basically stable.

[0095] Analysis of wave height along the route shows that the wave climb height at the nearshore sediment intrusion point is 15.22m, the wave climb height on the opposite bank is 7.89m, and the wave climb height at the dam site is 2.74m. Figure 7 The schematic diagram of the nearshore wave run-up height is shown in this invention. The wave heights at the dam site corresponding to internal friction angles of 27°, 28°, and 29° are 2.74m, 1.8m, and 0.9m, respectively. In this embodiment, the wave run-up height on the opposite bank, the wave height at the thalweg line, and the maximum wave height in the river channel were also studied.

[0096] In this embodiment, the selection of quantitative calculation and surge risk calculation is based on whether the exploration data and geological survey data of the landslide deposit are sufficient to establish a three-dimensional geological model: when a three-dimensional geological model can be established, quantitative calculation includes limit equilibrium analysis and three-dimensional numerical analysis, while surge risk calculation includes the Pan Jiazheng method and an integrated numerical model of landslide and surge. When a three-dimensional geological model cannot be established, quantitative calculation uses only limit equilibrium analysis, and surge risk calculation uses only the Pan Jiazheng method.

[0097] IV. Risk Assessment Comparing the calculation results of Pan Jiazheng's method and the integrated numerical model, the integrated numerical model, which considers the water-retaining and backwater effect of the dam, yields a higher calculated wave height at the dam site (2.74m) than the Pan Jiazheng method (0.14m). Considering the uncertainty of the internal friction angle parameter, there is a significant risk of secondary disasters after the collapse accumulation body becomes unstable.

[0098] Risk prevention and control measures include one or more of the following: monitoring and early warning, earthmoving and load reduction, anti-slide pile reinforcement, or drainage engineering. Based on the above assessment results, the following risk prevention and control measures are recommended: Monitoring and early warning: GNSS displacement monitoring points, deep inclinometer boreholes and groundwater level monitoring boreholes are set up in the area with poor stability on the left side of the accumulation body to establish a real-time monitoring and early warning system.

[0099] Cutting and reducing load: Cutting and reducing load on the left rear edge of the accumulator reduces the size of the sliding body and the potential surge height.

[0100] Drainage works: Intercepting drainage ditches are set up at the rear edge and sides of the accumulation to reduce the adverse effects of rainwater infiltration on stability.

[0101] Thus, this embodiment completes the entire technical process from determining slope grade and safety control standards, evaluating geological hazard stability, quantitatively calculating instability surge waves, to proposing risk prevention and control measures. It forms a closed-loop technology of "evaluation-prediction-prevention" throughout the entire process, which can scientifically assess the stability status of geological hazards, accurately calculate the height of instability surge waves and their impact on key projects, and propose targeted prevention and control measures accordingly.

[0102] This embodiment also provides a reservoir bank geological hazard risk assessment system based on the interaction between landslide movement and surge propagation, including: a standard setting module, which determines the slope grade of the target reservoir bank geological hazard and sets stability design safety control standards for it under persistent, transient, and accidental working conditions based on the slope grade; a stability evaluation module, which analyzes the geological conditions of the target reservoir bank geological hazard and, based on the geological conditions, evaluates the stability of the target reservoir bank geological hazard using a combination of qualitative analysis and quantitative calculation to obtain stability evaluation results; wherein, the quantitative calculation includes at least a two-dimensional rigid body limit equilibrium analysis using the limit equilibrium method; a surge prediction module, which, when the stability evaluation results indicate that the target reservoir bank geological hazard has an instability risk, uses an integrated landslide and surge numerical model to calculate the surge risk generated after the target reservoir bank geological hazard becomes instable, and obtains surge calculation results; wherein, the integrated landslide and surge numerical model couples the landslide movement process with the surge generation and propagation process in the same model; and a risk assessment module, which performs a risk assessment of the target reservoir bank geological hazard based on the stability evaluation results and the surge prediction results.

[0103] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation, characterized in that, Includes the following steps: Obtain geological data of the target reservoir bank, wherein the geological data includes at least one or more of the following: topographic data, material composition data, and slope boundary data; Based on the geological data, the stability of the target reservoir bank was quantitatively calculated using the Morgenstern-Price method to obtain the first stability assessment result; Based on the geological data, the Pan Jiazheng method was used to quantitatively calculate the surge risk of the target reservoir bank, and the first surge prediction result was obtained. Based on the first stability assessment result and the first surge prediction result, a risk assessment of geological hazards on the target reservoir bank is conducted to obtain the reservoir bank geological hazard risk assessment result.

2. The reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation as described in claim 1, characterized in that, The method further includes: A three-dimensional numerical analysis model was constructed using the three-dimensional finite difference software FLAC-3D. Based on the geological data, the three-dimensional numerical analysis model is used to simulate the elastoplastic values ​​of the target reservoir bank, thereby quantitatively calculating the stability of the target reservoir bank and obtaining a second stability assessment result; and / or The stability comparison results are obtained by comparing and analyzing the first stability assessment results with the second stability assessment results.

3. The reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation as described in claim 1, characterized in that, The method further includes: The Sassa model was written using the COMCOT open-source program to construct a numerical model of landslide surge. Based on the geological data, the landslide surge numerical model is used to simulate the surge conditions of the target reservoir bank, resulting in a second surge prediction result. The simulation of the surge conditions of the target reservoir bank includes at least one or more of the following: landslide movement, shovel entrapment, hydroplaning interaction, and surge generation and propagation; and / or By comparing and analyzing the first surge prediction result with the second surge prediction result, a surge risk comparison result is obtained.

4. The reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation as described in claim 3, characterized in that, The method further includes: Obtain the geometric morphological data of the downstream water-retaining structures of the target reservoir; Based on the geometric morphology data, the landslide surge wave numerical model is used to simulate the surge wave uplift effect, and a second surge wave prediction result is obtained based on the surge wave uplift effect.

5. The reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation as described in claim 1, characterized in that, The method further includes: Obtain overall geological data for the area to be evaluated; Based on the overall geological data, the corresponding slope grades are determined for multiple reservoir banks in the area to be evaluated, and the safety factor corresponding to the slope grade is obtained based on the slope grade. Based on the safety factor and the preset safety factor threshold, the target reservoir bank in the area to be evaluated is obtained.

6. The reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation as described in claim 5, characterized in that, The slope grade is calculated from one or more of the following: engineering grade data, building grade data, and slope location data.

7. The reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation as described in claim 3, characterized in that, The landslide surge numerical model includes: The landslide motion control equations simulate the movement of a landslide body on and / or underwater. The landslide motion control equations include gravity parameters, lateral pressure parameters, base friction parameters, and, when moving underwater, water drag force parameters and buoyancy parameters. The surge control equation simulates the generation and propagation process of surges. The surge control equation includes parameters of water body base friction, lateral pressure, and drag force of landslide on water. The landslide motion control equation and the surge control equation are solved discretely using the finite difference method, and the coupling of landslide motion and water motion is achieved in each calculation step through the relationship between action and reaction forces.

8. The reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation as described in claim 7, characterized in that, The landslide motion control equations include above-water motion control equations and underwater motion control equations; The control equations for waterborne motion are expressed as follows: in: The thickness of the landslide; , landslides , Flux in the direction; The erosion rate of the landslide; It is the acceleration due to gravity; , The landslide bottom and flat, Angle between planes Geometric morphology factor; This represents the lateral pressure coefficient of the landslide. , The internal friction angle of the landslide; , , , They are respectively Hydrodynamic correction factor or geometric projection factor for direction, , , landslides , , velocity in the direction; For landslide cohesion; The effective density of the landslide; This is the standard notation for partial derivatives, where and For the temporal variation of landslide dynamics, Additional resistance caused by terrain undulations; landslide erosion rate The calculation equation for the basal erosion rate proposed by Fraccarollo and Capart is as follows: In the formula: This represents the elevation of the landslide erosion surface. This represents the shear stress of the sliding body at the sliding surface. The shear strength of the eroded layer; The density of the eroded layer; The velocity of the sliding body; For time; The underwater motion control equation is expressed as follows: In the formula, The drag coefficient of the water body; , Geometric morphology factor Respectively, water bodies or reference objects are located at... The speed of movement in the direction, , The top surface of the landslide and flat, The angle between two planes; The surge control equation is expressed as follows: In the formula: The amplitude of the swell; , respectively surging waves , Flux in the direction; For water depth; This is the Manning coefficient; This is the density of water.

9. The reservoir bank geological hazard risk assessment method based on the interaction between landslide movement and surge propagation as described in claim 1, characterized in that, The method further includes: Based on the results of the reservoir bank geological disaster risk assessment, risk prevention and control measures are proposed, including one or more of the following: monitoring and early warning, earthmoving and load reduction, anti-slide pile reinforcement, or drainage engineering.

10. A reservoir bank geological hazard risk assessment system based on the interaction between landslide movement and surge propagation, characterized in that, include: The reservoir bank geological data acquisition module is used to acquire the address data of the target reservoir bank. The geological data includes at least one or more of the following: topographic data, material composition data, and slope boundary data. The reservoir bank stability quantitative calculation module uses the Morgenstern-Price method based on the geological data to quantitatively calculate the stability of the target reservoir bank and obtain the first stability assessment result. The reservoir bank surge risk quantitative calculation module uses the Pan Jiazheng method based on the geological data to quantitatively calculate the surge risk of the target reservoir bank and obtain the first surge prediction result. The reservoir bank geological hazard risk assessment module, based on the first stability assessment result and the first surge prediction result, is used to conduct a risk assessment of geological hazards on the target reservoir bank and obtain the reservoir bank geological hazard risk assessment result.

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