A method for monitoring the slope strength change of a waste dump side slope

Abstract

The application discloses a kind of for the slope strength variation monitoring method of waste dump side slope, it is related to slope strength variation monitoring field.The application is based on strength reduction method, combines three-dimensional data grid and monitoring data fusion, dynamically evaluates slope strength variation, and real-time identification side slope instability risk is carried out through intelligent early warning mechanism.The application is based on reinforcement strength reduction method, combines geological data, considers the nonlinear deformation characteristics of soil body, uses nonlinear constitutive model to dynamically describe the stress-strain relationship of soil body, and adjusts strength reduction coefficient in real time in monitoring process, improves the accuracy of side slope stability evaluation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of slope strength change monitoring, in particular to a slope strength change monitoring method for a waste dump slope. BACKGROUND

[0002] In the field of slope stability monitoring, existing technologies usually adopt methods such as surface deformation monitoring, strain monitoring, inclination monitoring, and groundwater level monitoring to evaluate the stability of the slope. Surface deformation monitoring mainly uses total station, GPS, InSAR and other means to obtain slope surface displacement data, strain monitoring relies on strain gauges or optical fiber sensors buried in the slope to measure local stress changes, inclination monitoring usually detects the inclination angle of the slope through an inclinometer, and groundwater level monitoring uses pore water pressure gauges or water level gauges to measure changes in underground water. In addition, some methods combine finite element analysis to numerically simulate the stress state of the slope and use the strength reduction method to estimate the safety factor of the slope to judge the stability of the slope.

[0003] However, the existing technology has certain limitations. First, surface deformation monitoring and inclination monitoring mainly rely on the macro deformation of the slope, which is difficult to reflect the internal stress changes in time and cannot predict the early damage trend. Second, although strain monitoring and groundwater level monitoring can obtain local data, the number of measuring points is limited and cannot fully reflect the mechanical state of the entire slope. In addition, traditional finite element analysis is usually based on static parameters and cannot update the mechanical properties of the slope in real time, resulting in lagging evaluation results or insufficient accuracy. In a dynamic changing environment, such as strong rainfall, earthquakes or excavation disturbance, the adaptability of existing methods is poor, and it is difficult to accurately evaluate the transient stability of the slope and the damage development process. SUMMARY

[0004] The present application proposes a slope strength change monitoring method for a waste dump slope, which is based on the strength reduction method, combines three-dimensional data grid with monitoring data fusion, dynamically evaluates the slope strength change, and identifies the slope instability risk in real time through an intelligent early warning mechanism.

[0005] A slope strength change monitoring method for a waste dump slope includes the following steps:

[0006] S1. Obtain the topographic data, geological parameters, hydrological data and real-time monitoring data of the waste dump slope, and construct a three-dimensional data grid using finite element mesh; establish a slope finite element calculation model according to the collected data, and calculate the initial shear strength and internal friction angle of the slope through the Mohr-Coulomb constitutive model;

[0007] S2. Based on the slope finite element calculation model, the strength reduction method is used to calculate the initial strength reduction coefficient of the slope body, and the minimum strength reduction coefficient satisfying the plastic zone penetration is obtained; the soil body parameters are adjusted according to the minimum strength reduction coefficient, and the slope finite element calculation model is updated;

[0008] S3. The real-time monitoring data is mapped to a three-dimensional data grid by using the Kriging interpolation method, and the local stress change is calculated in combination with the terrain data, geological parameters and hydrological data, and the slope mechanical parameters including the initial shear strength and internal friction angle of the slope are updated in real time;

[0009] S4. The shear stress ratio and the plastic zone expansion coefficient are calculated, and the regional reduction factor is defined; the strength reduction coefficient is dynamically adjusted based on the regional reduction factor, and the slope stability is evaluated in real time in combination with the updated slope mechanical parameters, to determine whether the slope is close to the critical state of instability.

[0010] Further, in the step S1, the terrain data specifically includes digital elevation model data and slope gradient and direction data; the geological parameters specifically include shear strength parameters, elastic modulus parameters and Poisson's ratio parameters; and the hydrological data specifically includes pore water pressure and permeability coefficient.

[0011] Further, in the step S1, the specific process of calculating the initial shear strength and internal friction angle of the slope by using the Mohr-Coulomb constitutive model is as follows:

[0012] S101. According to the finite element calculation model, the maximum principal stress and the minimum principal stress of each finite element discrete unit are extracted respectively, and the effective maximum principal stress and the effective minimum principal stress are calculated and obtained according to the influence of pore water pressure;

[0013] S102. According to the Mohr-Coulomb failure criterion, the shear strength of each finite element unit is calculated to form the shear stress distribution of the slope;

[0014] S103. The internal friction angle is calculated by regression fitting according to the shear stress distribution of the slope.

[0015] Further, in the step S101, the specific process of calculating the effective maximum principal stress and the effective minimum principal stress is as follows:

[0016] ;

[0017] ;

[0018] wherein, the represents the effective maximum principal stress, the represents the effective minimum principal stress, and the unit is Pa, and the represents a horizontal stress component, in Pa, the represents a vertical stress component, in Pa, the represents pore water pressure, in Pa, the represents a shear stress component, in Pa.

[0019] Further, the step S102, calculating the shear strength of each finite element unit, the specific process is represented as:

[0020] ;

[0021] wherein, the represents the shear strength of each finite element unit, in Pa, the represents cohesion, in Pa, the represents internal friction angle, in °.

[0022] Further, the step S2 specifically includes the following sub-steps:

[0023] S201. Set the initial strength reduction factor, according to the strength reduction formula, the soil parameters are reduced by the initial strength reduction factor, wherein the initial strength reduction factor is used to uniformly scale the soil parameters, so that the slope reaches the critical instability state;

[0024] S202. Update the slope finite element calculation model according to the reduced soil parameters;

[0025] S203. Find the minimum strength reduction factor of plastic zone penetration according to the plastic zone expansion coefficient;

[0026] S204. Take the minimum strength reduction factor that meets the plastic zone penetration as the strength reduction factor of the slope, and re-reduce the soil parameters according to the latest strength reduction factor according to the latest strength reduction factor. Update the slope finite element calculation model according to the reduced soil parameters.

[0027] Further, the step S3 specifically includes the following sub-steps:

[0028] S301. By Kriging interpolation method, combine real-time monitoring data with topographic data, geological parameters, hydrological data, calculate the physical quantity at three-dimensional grid nodes, and construct time-varying data field;

[0029] S302. According to the real-time monitoring data, the effective maximum principal stress and the effective minimum principal stress of the monitoring point at the current time are obtained, and the shear stress change of the monitoring point at the current time and the initial time is calculated according to the Mohr-Coulomb failure criterion;

[0030] S303. Correcting the shear strength and internal friction angle according to the local shear stress change;

[0031] S304. Updating the slope finite element model and the slope mechanical parameters through the corrected shear strength and internal friction angle.

[0032] Further, the step S4 specifically comprises the following sub-steps:

[0033] S401. Calculating the shear stress ratio and the plastic zone expansion coefficient through the optimization formula; determining the area reduction factor according to the calculation result;

[0034] S402. Dynamically updating the strength reduction coefficient of the slope through the area reduction factor;

[0035] S403. Re-executing the step S401 in combination with the updated strength reduction coefficient, calculating the stress state of the entire slope, and obtaining new plastic zone expansion coefficient and shear stress ratio data;

[0036] S404. Risk assessment on the new plastic zone expansion coefficient and shear stress ratio data.

[0037] Further, the step S401 specifically comprises the following sub-steps:

[0038] S4011. Calculating the shear stress ratio: , wherein the represents the shear stress ratio, the represents the corrected shear strength, the represents the shear strength of the slope at the current time t;

[0039] S4012. Calculating the plastic zone expansion coefficient according to the plastic zone area and the area of the entire slope: , wherein the represents the plastic zone expansion coefficient, the represents the plastic zone area, and the represents the area of the entire slope;

[0040] S4013. Determining the plastic zone influence coefficient and calculating the area reduction factor according to the calculated plastic zone expansion coefficient: , wherein the represents the plastic zone influence coefficient, and the represents the area reduction factor.

[0041] Further, in the step S404, the judgment standard of the risk assessment is specifically:

[0042] When the shear stress ratio is greater than or equal to 1.05 and the plastic zone expansion coefficient is greater than or equal to 0.90, it indicates that the shear stress of the slope body has exceeded the shear strength, and the plastic zone is close to complete penetration, and the slope body is in a critical failure or unstable state;

[0043] When the shear stress ratio is greater than or equal to 1.05 and the plastic zone expansion coefficient is greater than or equal to 0.90, it indicates that the shear stress of the slope body has exceeded the shear strength, and the plastic zone is close to complete penetration, and the slope body is in a critical failure or unstable state;

[0044] When the shear stress ratio is greater than or equal to 1.05 and the plastic zone expansion coefficient is greater than or equal to 0.90, it indicates that the shear stress of the slope body has exceeded the shear strength, and the plastic zone is close to complete penetration, and the slope body is in a critical failure or unstable state;

[0045] When the shear stress ratio is greater than or equal to 1.05 and the plastic zone expansion coefficient is greater than or equal to 0.90, it indicates that the shear stress of the slope body has exceeded the shear strength, and the plastic zone is close to complete penetration, and the slope body is in a critical failure or unstable state.

[0046] The beneficial effects of the application are:

[0047] The application is based on the strengthened strength reduction method, combined with geological data, considering the nonlinear deformation characteristics of the soil body, using a nonlinear constitutive model to dynamically describe the stress-strain relationship of the soil body, and adjusting the strength reduction coefficient in real time during monitoring, thereby improving the accuracy of slope stability evaluation. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 A method flowchart of a slope body strength change monitoring method for a waste dump slope is provided for the embodiments of the application. DETAILED DESCRIPTION

[0049] The technical solutions of the application will be further described in detail below with reference to the drawings, but the protection scope of the application is not limited to the following description.

[0050] In order to make the purpose, technical solutions and advantages of the application clearer, the application will be further described in detail with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the application and are not used to limit the application, that is, the described embodiments are only a part of the embodiments of the application, but not all the embodiments. The components of the embodiments of the application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0051] Therefore, the detailed description of the embodiments of the application provided below in the attached drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the protection of the application. It should be noted that the relational terms such as "first" and "second" and the like are merely used to distinguish one entity or operation from another, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations.

[0052] Moreover, the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article, or mechanical equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such a process, method, article, or mechanical equipment. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article, or mechanical equipment including the element.

[0053] The features and performances of the application are further described in detail below in conjunction with the embodiments.

[0054] Among them, as Figure 1 A slope body strength change monitoring method for a waste dump slope, comprising the following steps:

[0055] S1. Obtain the topographic data, geological parameters, hydrological data and real-time monitoring data of the waste dump slope, and construct a three-dimensional data grid using finite element mesh; establish a slope finite element calculation model according to the collected data, and calculate the initial shear strength and internal friction angle of the slope through the Mohr-Coulomb (Coulomb strength) constitutive model;

[0056] S2. Based on the slope finite element calculation model, calculate the initial strength reduction coefficient of the slope body using the strength reduction method, and obtain the minimum strength reduction coefficient that satisfies the through plastic zone; adjust the soil parameters according to the minimum strength reduction coefficient, and update the slope finite element calculation model;

[0057] S3. Using the Kriging interpolation method, map the real-time monitoring data to the three-dimensional data grid, and calculate the local stress change in combination with the topographic data, geological parameters and hydrological data, and update the slope body mechanical parameters in real time, the slope body mechanical parameters including the initial shear strength and internal friction angle of the slope;

[0058] S4. Calculate the shear stress ratio and plastic zone expansion coefficient, and define the regional reduction factor; dynamically adjust the strength reduction factor based on the regional reduction factor, and combine it with the updated slope mechanical parameters to evaluate the slope stability in real time and determine whether the slope is close to the critical state of instability.

[0059] Furthermore, in step S1, the terrain data specifically includes digital elevation model data and slope and aspect data; the geological parameters specifically include shear strength parameters, elastic modulus parameters, and Poisson's ratio parameters; and the hydrological data specifically includes pore water pressure and permeability coefficient.

[0060] Furthermore, in step S1, the specific process for calculating the initial shear strength and internal friction angle of the slope using the Mohr-Coulomb constitutive model is as follows:

[0061] S101. Based on the finite element calculation model, extract the maximum principal stress and minimum principal stress for each finite element discrete element, and calculate the effective maximum principal stress and effective minimum principal stress based on the influence of pore water pressure.

[0062] S102. Based on the Mohr-Coulomb failure criterion, calculate the shear strength of each finite element to form the shear stress distribution of the slope;

[0063] S103. Calculate the internal friction angle by regression fitting based on the shear stress distribution of the slope.

[0064] Furthermore, in step S101, the specific process for calculating the effective maximum principal stress and the effective minimum principal stress is as follows:

[0065] ;

[0066] ;

[0067] Among them, the Indicates the effective maximum principal stress, the The effective minimum principal stress is expressed in Pa. The horizontal stress component is represented by the unit Pa. This represents the vertical stress component, with units of Pa. The pore water pressure is expressed in Pa. This represents the shear stress component, with the unit being Pa.

[0068] Furthermore, in step S102, the specific process for calculating the shear strength of each finite element element is as follows:

[0069] ;

[0070] wherein the represents the shear strength of each finite element unit, with the unit of Pa, and the represents the cohesion, with the unit of Pa, and the represents the internal friction angle, with the unit of °.

[0071] Further, step S1 is used to obtain the basic data of the waste dump slope, and a finite element calculation model is established by using these data for subsequent strength change monitoring. Specifically, the terrain data includes digital elevation model data and slope gradient and aspect data, which are used to describe the geometric shape of the slope; the geological parameters include shear strength parameters, elastic modulus parameters and Poisson's ratio parameters, which determine the mechanical properties of the slope soil; the hydrological data includes pore water pressure and permeability coefficient, which are used to evaluate the influence of groundwater on the stability of the slope. Through the collected data, a three-dimensional data grid is constructed, and the calculation model can reflect the spatial distribution characteristics of the slope. Further, based on the collected data, a slope finite element calculation model is established, and the Mohr-Coulomb (Coulomb strength) constitutive model is used to calculate the initial shear strength and internal friction angle of the slope. The Mohr-Coulomb (Coulomb strength) constitutive model is a theory for describing the shear failure behavior of soil, which can calculate the stress state of the slope under different stress conditions and provide a basis for subsequent strength reduction calculation; and the discrete method of the finite element grid provides initial calculation conditions for slope strength change monitoring.

[0072] In addition, the monitoring data refers to the real-time state information of the slope collected by the monitoring equipment such as strain gauges, stress gauges, pore pressure gauges, displacement gauges and other monitoring equipment arranged on the waste dump slope, including but not limited to principal stress, shear stress, pore water pressure, displacement change, seepage rate and groundwater level and other data. The above monitoring data is real-time returned through a wireless acquisition system, and is spatially interpolated and time-series fused in the three-dimensional data grid, which is used to dynamically update the slope mechanical parameters in the slope finite element model, and reflects the actual response state of the slope structure with time.

[0073] Further, step S2 specifically includes the following sub-steps:

[0074] S201. Set the initial strength reduction coefficient, and reduce the soil parameters according to the initial strength reduction coefficient according to the strength reduction formula, wherein the initial strength reduction coefficient is used to uniformly scale the soil parameters so that the slope reaches a critical unstable state;

[0075] S202. Update the slope finite element calculation model according to the reduced soil parameters;

[0076] S203. Find the minimum strength reduction coefficient of the plastic zone through the plastic zone expansion coefficient;

[0077] S204. Take the minimum strength reduction factor satisfying the plastic zone penetration as the strength reduction factor of the slope, and re-reduce the soil parameters according to the latest strength reduction factor, and update the slope finite element calculation model according to the reduced soil parameters.

[0078] Specifically, the soil parameters refer to the geomechanical and hydrological mechanical characteristic indexes required for constructing the slope finite element calculation model, including shear strength parameters (internal friction angle and cohesion), elastic parameters (elastic modulus and Poisson's ratio), permeability parameters (porosity ratio and permeability coefficient), and physical parameters (dry density and pore water pressure). The above parameters are mainly obtained through in-situ tests (such as standard penetration test, static cone penetration), laboratory tests (such as triaxial shear and permeability test) and geological survey data, and can also be dynamically corrected by mechanical inversion algorithm combined with monitoring data, for updating the stress state and stability analysis results of the slope at each time.

[0079] Further, step S1 uses the strength reduction method to calculate the initial strength reduction factor of the slope based on the finite element calculation model, and adjusts the soil parameters to reflect the actual stress state of the slope. Specifically, an initial strength reduction factor needs to be set, which is used to uniformly scale the soil parameters to make the slope reach a critical unstable state. The shear strength and internal friction angle of the soil are adjusted through the strength reduction formula, and the calculation result can reflect the potential instability trend of the slope. Further, the slope finite element calculation model is updated according to the reduced soil parameters to adapt to the new mechanical parameters. The plastic zone expansion coefficient is used to find the minimum strength reduction factor when the plastic zone of the slope penetrates, and the plastic zone expansion coefficient is used to describe the expansion degree of the plastic deformation inside the slope, reflecting the local damage trend of the slope under stress state. When the plastic zone penetrates, the slope reaches the most dangerous state, so the minimum strength reduction factor that meets this condition needs to be found; and the minimum strength reduction factor is taken as the final strength reduction factor of the slope, and the soil parameters are re-adjusted based on the latest strength reduction factor to ensure that the slope finite element calculation model can accurately reflect the stress state of the slope and serve as the basis for subsequent monitoring.

[0080] Further, the step S3 specifically includes the following sub-steps:

[0081] S301. Calculate the physical quantities at the three-dimensional grid nodes by combining the real-time monitoring data with the terrain data, geological parameters and hydrological data through Kriging interpolation method, and construct the time-varying data field;

[0082] S302. According to the real-time monitoring data, obtain the effective maximum principal stress and effective minimum principal stress of the monitoring point at the current time, and calculate the shear stress change amount of the monitoring point at the current time and the initial time according to the Mohr-Coulomb failure criterion;

[0083] S303. Correcting the shear strength and internal friction angle according to the local shear stress change;

[0084] S304. Updating the slope finite element model and the slope mechanical parameters through the corrected shear strength and internal friction angle.

[0085] Specifically, step S3 integrates the real-time monitoring data into a three-dimensional data grid and calculates the local stress change in combination with the terrain, geological and hydrological data, so as to realize the real-time updating of the slope mechanical parameters. Specifically, the Kriging interpolation method is used to map the monitoring data to the three-dimensional grid, so that it forms a continuous change trend in the spatial range, thereby reflecting the dynamic stress distribution of the slope. The Kriging interpolation method can reasonably estimate the unknown area by using the existing monitoring data, thereby improving the data integrity. Further, according to the real-time monitoring data, the effective maximum principal stress and the effective minimum principal stress of the monitoring point at the current time are obtained, and the shear stress change of the monitoring point at the current time is calculated in combination with the Mohr-Coulomb failure criterion, so as to understand the stress distribution change of the slope at different time points; and the shear strength and the internal friction angle of the slope are corrected according to the local shear stress change, and the force characteristics of the slope are reflected through the corrected parameters. Based on the corrected shear strength and internal friction angle, the slope finite element model is updated, so that it can more accurately describe the mechanical state of the slope at different time nodes, and provide data support for subsequent stability evaluation.

[0086] Exemplarily, the detailed process of step S3 is as follows:

[0087] The Kriging interpolation method is used to map the monitoring point data to the entire three-dimensional data grid:

[0088] ;

[0089] The , and are the measured maximum stress, minimum stress and pore pressure of the monitoring point i at the current time t, represents Kriging interpolation, the n represents the total number of all monitoring points, and the , and represent the maximum principal stress, the minimum principal stress and the pore pressure mapped to the three-dimensional data grid;

[0090] Calculate the local principal stress increment:

[0091] ;

[0092] The represents the initial time, and the and denotes the local maximum principal stress and the local minimum principal stress, denotes the local pore pressure .

[0093] The change of effective stress is calculated as:

[0094] ;

[0095] The and denote the change of effective maximum stress and effective minimum stress.

[0096] The local shear stress increment is calculated as:

[0097] According to the Mohr-Coulomb failure criterion, the shear stress is:

[0098] ;

[0099] The denotes the local shear stress, the and denote the local maximum stress and the local minimum stress

[0100] The shear stress change is calculated as:

[0101] ;

[0102] The denotes the shear stress change, the denotes the local shear stress at the current time t mapped to the three-dimensional data grid, and the denotes the local shear stress at the initial time t0mapped to the three-dimensional data grid.

[0103] The normalized shear stress change is:

[0104] ;

[0105] The denotes the normalized shear stress change, and the denotes the maximum shear stress in the initial state.

[0106] Further, the step S4 specifically comprises the following sub-steps:

[0107] S401. Calculate the shear stress ratio and the plastic zone expansion coefficient through an optimization formula; determine the zone reduction factor according to the calculation result;

[0108] S402. Dynamically update the strength reduction coefficient of the slope body based on the zone reduction factor;

[0109] S403. Re-execute step S401 to calculate the stress state of the entire slope body, obtain new plastic zone expansion coefficient and shear stress ratio data, in combination with the updated strength reduction factor;

[0110] S404. Risk assessment on the new plastic zone expansion coefficient and shear stress ratio data.

[0111] Specifically, step S4 calculates the shear stress ratio and plastic zone expansion coefficient, and defines the regional reduction factor based on these data to dynamically adjust the strength reduction factor, so as to evaluate the stability of the slope body in real time. The combination of the updated strength reduction factor in step S403 means that the regional reduction factor is combined with the updated strength reduction factor to re-calculate the stress state of the entire slope body, so as to obtain new plastic zone expansion coefficient and shear stress ratio data. The material parameters (such as ) acting on the finite element model of the slope body are updated, and the stress state of the slope body is re-calculated after updating the material parameters, so as to obtain new shear stress distribution and plastic zone morphology, and then re-calculate the shear stress ratio and plastic zone expansion coefficient. Specifically, the shear stress ratio and plastic zone expansion coefficient are calculated by using an optimization formula, the shear stress ratio is used to evaluate whether the shear strength of the slope body is sufficient, and the plastic zone expansion coefficient is used to judge the development trend of the plastic deformation inside the slope body. When the shear stress ratio is large and the plastic zone expansion coefficient is high, the slope body has a large instability risk. Further, according to the calculation results, the regional reduction factor is determined, and the strength reduction factor of the slope body is dynamically updated based on the regional reduction factor, so as to more accurately reflect the mechanical properties of the slope body. Next, in combination with the updated strength reduction factor, the stress state of the entire slope body is re-calculated to obtain new plastic zone expansion coefficient and shear stress ratio data, which are used for further risk assessment. In the risk assessment process, if the shear stress ratio is greater than 1.05 and the plastic zone expansion coefficient is greater than 0.90, it means that the slope body has reached a critical instability state and a landslide may occur; if the shear stress ratio is between 0.95 and 1.05, and the plastic zone expansion coefficient is between 0.60 and 0.90, it means that the slope body has a local damage risk and needs to be monitored and managed; if the shear stress ratio is between 0.85 and 0.95, and the plastic zone expansion coefficient is between 0.30 and 0.60, it means that the slope body is stable as a whole, but there may be local stress concentration, which needs to be early warned; if the shear stress ratio is less than 0.85 and the plastic zone expansion coefficient is less than 0.30, it means that the slope body is in a stable state and has no obvious sliding risk. Through this series of calculations and assessments, the precise monitoring of the strength change of the slope body can be realized, and corresponding management measures can be taken before the slope instability risk occurs.

[0112] Further, the step S401 specifically includes the following sub-steps:

[0113] S4011. Calculate the shear stress ratio: , wherein represents the shear stress ratio, and represents the corrected shear strength, the corrected shear stress is calculated by the following formula: represents the shear strength of the slope at the current time t; at the initial time, since the monitoring disturbance correction has not been introduced, the corrected shear stress is set equal to the initial shear strength, as a reference benchmark for the subsequent dynamic evolution of the shear stress ratio. Starting from t>0, the shear strength is corrected by introducing the monitoring data, and the shear stress ratio is calculated.

[0114] S4012. Calculate the plastic zone expansion coefficient according to the plastic zone area and the total slope area: , the plastic zone expansion coefficient is calculated by the following formula: , the plastic zone expansion coefficient is calculated by the following formula: , the plastic zone area is calculated by the following formula: , the total slope area is calculated by the following formula:

[0115] S4013. Determine the plastic zone influence coefficient, and calculate the area reduction factor according to the calculated plastic zone expansion coefficient: , the plastic zone influence coefficient is calculated by the following formula: , the plastic zone influence coefficient is calculated by the following formula: , the area reduction factor is calculated by the following formula.

[0116] Further, in the step S404, the judgment criteria of risk assessment are as follows:

[0117] When the shear stress ratio is ≥1.05, and the plastic zone expansion coefficient is ≥0.90, it indicates that the shear stress of the slope has exceeded the shear strength, and the plastic zone is close to complete penetration, the slope is in a critical failure or unstable state;

[0118] When 0.95≤shear stress ratio<1.05 and 0.60≤plastic zone expansion coefficient<0.90, it indicates that the shear stress of the slope is close to the shear strength, and part of the plastic zone has expanded but has not completely penetrated, there is a local damage risk;

[0119] When 0.85≤shear stress ratio<0.95 and 0.30≤plastic zone expansion coefficient<0.60, it indicates that the slope as a whole is still in a stable state, but there is a certain trend of local stress concentration or plastic zone expansion, which needs early warning and observation;

[0120] When the shear stress ratio is <0.85 and the plastic zone expansion coefficient is <0.30, it indicates that the shear stress of the slope is much smaller than the shear strength, and the plastic zone expansion is minimal, the slope is in a stable state, and there is no obvious sliding risk.

[0121] In summary, the method proposed in this embodiment is used to monitor the slope body strength change of the waste dump slope, and the slope stability is evaluated based on finite element calculation and real-time monitoring data. First, the terrain data, geological parameters, hydrological data and real-time monitoring data of the waste dump slope are collected, and a three-dimensional data grid is constructed to establish a slope finite element calculation model. The initial shear strength and internal friction angle of the slope body are calculated by the Mohr-Coulomb (Coulomb strength) constitutive model to obtain the basic mechanical parameters. The initial strength reduction factor of the slope body is calculated by using the strength reduction method, and the minimum strength reduction factor that satisfies the plastic zone penetration is obtained, and the soil parameters are adjusted to update the finite element calculation model, so that the model is more consistent with the true state of the slope body. Then, the real-time monitoring data is mapped to the three-dimensional data grid by using the Kriging interpolation method, and the local stress change is calculated combined with the terrain, geological and hydrological data to update the slope mechanical parameters, so that they contain real-time information. Next, the shear stress ratio and plastic zone expansion coefficient are calculated, and the regional reduction factor is defined, and the strength reduction factor is dynamically adjusted based on the regional reduction factor, and the slope stability is evaluated combined with the updated slope mechanical parameters to judge whether the slope body is close to the critical state of instability. In order to realize each step, step S1 is refined to obtain terrain, geological and hydrological data, and the initial shear strength and internal friction angle are calculated by the Mohr-Coulomb (Coulomb strength) constitutive model, wherein the shear strength calculation is based on the principal stress and pore water pressure, and the internal friction angle is obtained by regression fitting. Step S2 includes setting the initial strength reduction factor, scaling the soil parameters based on the reduction formula, and updating the finite element model; then the minimum strength reduction factor of the slope body is determined by the plastic zone expansion coefficient, and the soil parameters are adjusted again and the finite element model is updated to meet the requirements of reflecting the actual critical state. Step S3 is to calculate the physical quantity at the three-dimensional grid node by using the Kriging interpolation method combined with the real-time monitoring data, establish a time-varying data field, and calculate the shear stress change at the current time, update the finite element model and the slope mechanical parameters after correcting the shear strength and the internal friction angle. Step S4 specifically performs the calculation of shear stress ratio and plastic zone expansion coefficient, dynamically adjusts the strength reduction factor according to the regional reduction factor, and cyclically updates the stress state, and finally performs risk assessment. According to the risk assessment standard, when the shear stress ratio is greater than or equal to 1.05 and the plastic zone expansion coefficient is greater than or equal to 0.90, the slope body enters the critical failure or instability state; when 0.95≤ shear stress ratio <1.05 and 0.60≤ plastic zone expansion coefficient <0.90, the slope body approaches the shear strength, and there is a local risk of damage; when 0.85≤ shear stress ratio <0.95 and 0.30≤ plastic zone expansion coefficient <0.60, the slope body is stable as a whole but needs to be observed; when shear stress ratio <0.85 and plastic zone expansion coefficient <0.30, the slope body is in a stable state and has no obvious sliding risk. The whole process combines numerical calculation, data interpolation and real-time monitoring to realize high-precision monitoring and stability evaluation of the slope strength change, and to ensure the safety of the waste dump slope.

[0122] The foregoing is considered as illustrative only of the principles of the application. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the application to the exact construction and operation described. Accordingly, all such variations are intended to be included within the scope of the present application as defined in the claims below and their equivalents.

Claims

1. A method for monitoring slope strength changes at spoil heaps, characterized in that, Includes the following steps: S1. Acquire topographic data, geological parameters, hydrological data, and real-time monitoring data of the spoil disposal site slope, and construct a three-dimensional data grid using a finite element mesh; establish a finite element calculation model of the slope based on the collected data, and calculate the initial shear strength and internal friction angle of the slope using the Mohr-Coulomb constitutive model; S2. Set an initial strength reduction factor. According to the strength reduction formula, reduce the soil parameters according to the initial strength reduction factor. The initial strength reduction factor is used to uniformly scale the soil parameters so that the slope reaches the critical instability state. Update the slope finite element calculation model according to the reduced soil parameters. Find the minimum strength reduction factor for plastic zone penetration according to the plastic zone expansion coefficient. Use the minimum strength reduction factor that satisfies plastic zone penetration as the slope strength reduction factor. Reduce the soil parameters again according to the latest strength reduction factor. Update the slope finite element calculation model according to the reduced soil parameters. S3. Using the Kriging interpolation method, real-time monitoring data is mapped to a three-dimensional data grid, and local stress changes are calculated by combining topographic data, geological parameters, and hydrological data, and the slope mechanical parameters are updated in real time. The slope mechanical parameters include the initial shear strength and internal friction angle of the slope. S4. Calculate the shear stress ratio and plastic zone expansion coefficient, and define the regional reduction factor; dynamically adjust the strength reduction factor based on the regional reduction factor, and combine it with the updated slope mechanical parameters to evaluate the slope stability in real time and determine whether the slope is close to the critical state of instability. Step S4 specifically includes the following sub-steps: S401. Calculate the shear stress ratio and plastic zone expansion coefficient using optimized formulas; determine the region reduction factor based on the calculation results; S402. Dynamically update the slope strength reduction coefficient based on the regional reduction factor; S403. Combine the updated strength reduction factor and repeat step S401 to calculate the stress state of the entire slope and obtain new plastic zone expansion factor and shear stress ratio data; S404. Conduct a risk assessment on the new plastic zone extension coefficient and shear stress ratio data; Step S401 specifically includes the following sub-steps: S4011. Calculate the shear stress ratio: The Indicates the shear stress ratio, the This represents the modified shear strength, the This represents the shear strength of the slope at the current time t; S4012. Calculate the plastic zone expansion coefficient based on the area of ​​the plastic zone and the total area of ​​the slope: The The plastic zone expansion coefficient is represented by the following. Represents the area of ​​the plastic region, the This represents the area of ​​the total slope. S4013. Determine the influence coefficient of the plastic zone, and calculate the region reduction factor based on the calculated plastic zone expansion coefficient: The The coefficient representing the influence of the plastic zone is described below. This represents the regional reduction factor.

2. The method for monitoring slope strength changes at a spoil heap as described in claim 1, characterized in that, In step S1, the terrain data specifically includes digital elevation model data and slope and aspect data; the geological parameters specifically include shear strength parameters, elastic modulus parameters, and Poisson's ratio parameters; and the hydrological data specifically includes pore water pressure and permeability coefficient.

3. The method for monitoring slope strength changes at a spoil heap as described in claim 1, characterized in that, In step S1, the specific process for calculating the initial shear strength and internal friction angle of the slope using the Mohr-Coulomb constitutive model is as follows: S101. Based on the finite element calculation model, extract the maximum principal stress and minimum principal stress for each finite element discrete element, and calculate the effective maximum principal stress and effective minimum principal stress based on the influence of pore water pressure. S102. Based on the Mohr-Coulomb failure criterion, calculate the shear strength of each finite element to form the shear stress distribution of the slope; S103. Calculate the internal friction angle by regression fitting based on the shear stress distribution of the slope.

4. The method for monitoring slope strength changes at a spoil heap as described in claim 3, characterized in that, In step S101, the specific process for calculating the effective maximum principal stress and the effective minimum principal stress is as follows: ； Among them, the These represent the effective maximum principal stress and the effective minimum principal stress, respectively, in Pa. The horizontal stress component is represented by the unit Pa. This represents the vertical stress component, with units of Pa. The pore water pressure is expressed in Pa. This represents the shear stress component, with the unit being Pa.

5. The method for monitoring slope strength changes at a spoil heap as described in claim 4, characterized in that, In step S102, the specific process for calculating the shear strength of each finite element is as follows: ； Among them, the This represents the shear strength of each finite element element, expressed in Pa. This represents cohesion, measured in Pa. This represents the internal friction angle, expressed in degrees (°).

6. The method for monitoring slope strength changes at a spoil heap as described in claim 1, characterized in that, Step S3 specifically includes the following sub-steps: S301. By combining real-time monitoring data with topographic data, geological parameters, and hydrological data using the Kriging interpolation method, physical quantities at three-dimensional grid nodes are calculated to construct a time-varying data field; S302. Based on real-time monitoring data, obtain the effective maximum principal stress and effective minimum principal stress at the monitoring point at the current moment, and calculate the change in shear stress at the monitoring point at the current moment compared with the initial moment according to the Mohr-Coulomb failure criterion. S303. Correct the shear strength and internal friction angle based on local shear stress variations; S304. Update the finite element model and mechanical parameters of the slope using the corrected shear strength and internal friction angle.

7. The method for monitoring slope strength changes at a spoil heap as described in claim 1, characterized in that, In step S404, the specific criteria for risk assessment are as follows: When the shear stress ratio is ≥1.05 and the plastic zone expansion coefficient is ≥0.90, it indicates that the shear stress of the slope has exceeded the shear strength, and the plastic zone is close to being fully penetrated, and the slope is in a critical failure or already unstable state. When 0.95≤shear stress ratio<1.05 and 0.60≤plastic zone expansion coefficient<0.90, it indicates that the shear stress of the slope is close to the shear strength, some plastic zones have expanded but have not been fully connected, and there is a risk of local failure. When 0.85≤shear stress ratio<0.95 and 0.30≤plastic zone expansion coefficient<0.60, it indicates that the slope as a whole is still in a stable state, but there is a certain tendency for local stress concentration or plastic zone expansion, which requires early warning and observation. When the shear stress ratio is less than 0.85 and the plastic zone expansion coefficient is less than 0.30, it indicates that the shear stress of the slope is much less than its shear strength, the plastic zone expansion is minimal, the slope is in a stable state, and there is no obvious risk of sliding.

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