Method for evaluating time-varying stability of side slope containing mining cavern group under blasting vibration effect

Abstract

The invention provides a method for evaluating the time-varying stability of a slope containing a mining cavern group under the action of blasting vibration, and belongs to the technical field of evaluation of the time-varying stability of the slope containing the mining cavern group. In order to solve the technical problems that the current slope time-varying stability evaluation has limitations in the aspects of accurately representing the influence of a dynamic load effect and a rock-soil body accumulated damage mechanism, and the research on the aspects of the influence of a mining cave group on the slope stability and the slope deformation and damage evolution law under the blasting vibration effect is insufficient, the invention provides the slope time-varying stability evaluation method. According to the technical scheme, monitoring points are arranged on an end slope toe and different elevation steps of the strip mine, blasting data are collected, and dynamic response characteristics in blasting operation are studied; constructing a physical model of a vibration table test according to actual slope spatial morphological characteristics, and researching a dynamic instability evolution mechanism of the slope containing the mining cavern group under the action of dynamic and static loads on the basis of the constructed physical model; the method is applied to stability control of the open pit coal mine end slope mining side slope.

Description

TECHNICAL FIELD

[0001] The application provides a time-varying stability evaluation method for a slope containing a mining tunnel group under blasting vibration, and belongs to the technical field of time-varying stability evaluation of the slope containing the mining tunnel group. BACKGROUND

[0002] With the continuous expansion of the mining scale of mineral resources, the recovery of the resources covered by the end slope of the open-pit mine has become the core issue of the industry, and the end slope recovery technology provides a feasible scheme for the efficient recovery of the covered resources. However, the mining tunnel group formed by the mining activities will cause significant disturbance to the original stress field of the slope, and then induce the deformation of the rock mass, which seriously threatens the stability of the slope. More complexly, the vibration wave generated by the blasting operation of the mine will not only cause additional inertial force to the slope rock mass, but also cause strength deterioration and cumulative damage of the rock and soil mass due to the long-term and frequent action of the vibration wave, which further aggravates the risk of slope instability.

[0003] At present, the methods for analyzing the dynamic stability of the slope mainly include two categories of permanent displacement and dynamic stability coefficient (such as the pseudo-static method and the dynamic time-history analysis method). For the research on the influence of blasting vibration, the pseudo-static method and the time-history analysis method are mainly used to evaluate the stability of the slope. However, these methods still have limitations in accurately characterizing the influence of the dynamic load and the cumulative damage mechanism of the rock and soil mass. The influence mechanism of the mining tunnel group formed by the end slope mining on the stability of the slope and the research on the evolution law of the deformation and failure of the slope under the action of blasting vibration are still insufficient. SUMMARY

[0004] In order to solve the technical problems in the background art, the technical scheme adopted by the application is as follows: a time-varying stability evaluation method for a slope containing a mining tunnel group under blasting vibration, comprising the following evaluation steps:

[0005] Step 1: arranging monitoring points on the slope toe and different elevation steps of the end slope of the open-pit mine, collecting blasting data and researching the dynamic response characteristics in the blasting operation, and then selecting the final physical and mechanical parameters of each rock layer according to the production data of the mine area, and the specific method is as follows:

[0006] Step 1.1: arranging monitoring points on the slope toe and different elevation steps of the end slope of the open-pit mine using a vibration meter, and collecting the velocity time-history data of each monitoring point in the horizontal and vertical directions during the blasting operation;

[0007] Step 1.2: based on the vibration velocity data of each direction of the monitoring points, an optimized Sadaovsky formula is used to establish a prediction model of the global peak vibration velocity.

[0008] Step 2: constructing a physical model of the shaking table test according to the spatial form characteristics of the actual slope, and researching the dynamic instability evolution mechanism of the slope containing the mining tunnel group under the action of dynamic and static loads based on the constructed physical model, and the specific method is as follows:

[0009] Step 2.1: Based on the size of the prototype slope, a rigid model box is designed and made according to the geometric similarity ratio;

[0010] Step 2.2: Determine the similarity constant of the physical model and the actual slope shape, and make a physical model that can simulate the dynamic characteristics of the actual slope according to the similarity theory;

[0011] Step 2.3: Determine the type and ratio of the similar simulation material;

[0012] Step 2.4: The model is made by matching the actual slope rock properties, and soil pressure boxes, distributed strain sensing optical fibers, and non-contact three-dimensional optical photogrammetry system monitoring equipment are laid during the model pouring process;

[0013] Step 2.5: Pour the model every 20mm thick and tamp once, from bottom to top in order to pour the base sandstone, coal seam, mud sandstone interbedded, and loess, after the model is completed, maintenance is carried out, and two-dimensional and three-dimensional slope model steps are excavated and mined;

[0014] Step 2.6: Based on the blasting vibration velocity time history curve of the field monitoring point, the vibration wave frequency of the physical model is determined according to the similarity theory, and it is loaded.

[0015] Step 3: Evaluate the time-varying stability of the slope under dynamic and static loads, the specific method is:

[0016] Step 3.1: According to the acceleration data collected by the monitoring equipment, use the tfestimate function in MATLAB to process the collected acceleration data, construct the absolute transfer function, and extract the imaginary part-frequency characteristic curve to identify the first-order natural frequency and damping ratio of the model, and calculate the slope damage degree;

[0017] Based on the change of the first-order natural frequency, the slope damage degree D is calculated by the following formula:

[0018] ;

[0019] ;

[0020] In the formula: D is the slope damage degree, f0, f respectively represent the first-order natural frequency of the rock-soil body before and after vibration loading, is the reduction rate of the natural frequency of the rock-soil body;

[0021] Step 3.2: Quantitatively evaluate the dynamic stability of the slope under the action of blasting vibration load, calculate the dynamic time safety factor of the slope under blasting vibration, and the calculation formula is:

[0022] ;

[0023] In the formula: F s The dynamic time history safety factor for the slope is given by E, where n is the total number of slices in the slice method, and E is the slope's dynamic time history safety factor. i For the normal force between the blocks, ξ i H is the force transmission coefficient. i For the anti-slip force component, G i This is the component of the downward force.

[0024] Step 4: Establish a two-dimensional numerical simulation model under blasting vibration, and perform simulation calculations for the initial static analysis and dynamic analysis stages respectively. The specific method is as follows:

[0025] Step 4.1: Determine the initial stress field distribution of the slope under its own weight;

[0026] Step 4.2: By constraining the X-direction displacements on both sides of the model and the X and Y-direction displacements at the bottom, calculate the initial static equilibrium state of the slope under its own weight within the framework of the linear elastic constitutive model;

[0027] Step 4.3: Use an equivalent linear dynamic model, apply displacement constraints in the Y direction on both sides of the model boundary conditions, apply displacement constraints in the X and Y directions at the bottom, and simultaneously input horizontal and vertical blasting vibration waves. Iterate this process repeatedly until the slope becomes unstable and fails.

[0028] Step 4.4: By analyzing the timing of the peak XY shear strain at the slope toe monitoring point and the peak horizontal displacement at the slope top monitoring point, the temporal characteristics of slope instability and failure are determined.

[0029] Step 4.5: The stability of the two-dimensional slope numerical model is evaluated using the minimum average safety factor, and the cumulative damage effect under multiple blasting actions is investigated.

[0030] The beneficial effects of this invention compared to existing technologies are as follows: Addressing the stability problem of slopes containing mining tunnels under blasting vibration, this invention uses open-pit mine slopes as an engineering basis and comprehensively employs on-site vibration testing, large-scale shaking table model testing, and numerical simulation to systematically reveal the dynamic response characteristics, cumulative damage evolution laws, and gradual instability mechanisms of such slopes under blasting vibration. Furthermore, it constructs a stability assessment method suitable for this type of slope. This invention elucidates the disaster mechanism of slopes containing mining tunnels under dynamic blasting loads, revealing the cumulative effect of mining tunnels under blasting vibration and its dominant role in overall instability. It can provide a scientific basis for disaster prevention and control and blasting parameter optimization in similar projects, improve the theoretical system of slope stability containing mining tunnels, and provide key theoretical basis and technical support for disaster prevention and safe and efficient resource recovery. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings:

[0032] Figure 1 The step flow chart is for the time-varying stability evaluation method of the slope containing the group of mining chambers under the action of blasting vibration of the application;

[0033] Figure 2 The setting layout schematic diagram of the field monitoring point is for the application;

[0034] Figure 3 The schematic diagram of the time-history curve of the X-direction velocity monitored is for the application;

[0035] Figure 4 The prediction model diagram of the peak velocity of the monitoring point at different elevations of the slope is for the application;

[0036] Figure 5 The test device effect diagram for constructing the physical model is for the application;

[0037] Figure 6 The physical model monitoring instrument layout schematic diagram is for the application;

[0038] Figure 7 The statistical diagram of the earth pressure evolution law under the action of chamber excavation is for the application;

[0039] Figure 8 The statistical diagram of the earth pressure evolution law under the action of blasting vibration is for the application;

[0040] Figure 9 The statistical diagram of the strain distribution law measured by the distributed optical fiber sensor is for the application;

[0041] Figure 10 The relationship diagram of the slope damage degree and blasting vibration is for the application;

[0042] Figure 11 The time evolution curve diagram of the safety factor is for the application;

[0043] Figure 12 The numerical simulation model and monitoring point layout schematic diagram is for the application;

[0044] Figure 13 The initial static analysis effect diagram is for the application;

[0045] Figure 14 The dynamic response effect diagram of the numerical model is for the application;

[0046] Figure 15 The effect diagram of the peak response and damage sequence time is for the application;

[0047] Figure 16 The time-history curve diagram of the slope safety factor is for the application. DETAILED DESCRIPTION

[0048] As Figures 1 to 16As shown, the present application provides a time-varying stability evaluation method of a slope containing a group of mining tunnels under the action of blasting vibration, which is applied to the stability control of a slope in an open-pit coal mine, and the method first arranges monitoring points at the toe of the slope and different elevation steps of the open-pit mine, collects blasting data, studies the dynamic response characteristics of the coal and rock mass under the action of blasting vibration, establishes a global peak vibration velocity prediction mathematical model based on an optimized Sadaovsky formula, constructs a shaking table test similar physical model according to the spatial form characteristics of the actual slope, determines the similarity constants, materials and proportions, lays out monitoring equipment, and performs model manufacturing, maintenance, mining tunnel excavation and vibration loading parameter, studies the dynamic instability evolution mechanism of the slope containing the mining tunnels, and proposes a time-varying stability evaluation method of the slope under the action of dynamic and static loads.

[0049] Further, as shown in the Figure 1 , the present application provides a time-varying stability evaluation method of a slope containing a group of mining tunnels under the action of blasting vibration, which specifically includes the following steps:

[0050] Step 1: Arranging monitoring points at the toe of the slope and different elevation steps of the open-pit mine, collecting blasting data and studying the dynamic response characteristics in blasting operation, and then selecting the final physical and mechanical parameters of each rock layer according to the production data of the mine area, specifically including:

[0051] Step 1.1: Using an L20-S type intelligent vibration meter (sampling threshold 0.03 mm / s) to arrange 5 monitoring points at the toe and different elevation steps and perform 3 blasting tests, monitoring the X-direction velocity time history curve of each point, and the specific monitoring point arrangement is as shown in the Figure 2 , the monitored X-direction velocity time history curve is as shown in the Figure 3 .

[0052] Step 1.2: Based on the peak vibration velocity of the monitoring points, an improved Sadaovsky formula is used for fitting, and a global peak vibration velocity prediction mathematical model is constructed, and the expression is:

[0053] ;

[0054] In the formula: V is the vibration velocity prediction value; Q is the maximum explosive quantity per time; R is the straight-line distance from the explosion source to the monitoring point; H is the vertical distance from the explosion source to the monitoring point; k is the site coefficient; alpha 1 is the blasting seismic wave attenuation index; and alpha 2 is the attenuation coefficient under the influence of elevation difference.

[0055] In this embodiment, the X, Y and Z direction peak vibration velocities increase with the increase of explosive quantity, decrease with the increase of blast center distance, and increase obviously with the increase of elevation difference. Under the action of blasting, the slope steps have an elevation amplification effect, and the peak vibration velocities in different directions are as shown in the Figure 4 , in which part a is the X-direction peak vibration velocity, part b is the Y-direction peak vibration velocity, and part c is the Z-direction peak vibration velocity.

[0056] Step 2: According to the actual spatial form characteristics of the slope, a shaking table test similar physical model is constructed, and based on the model test, the dynamic instability evolution mechanism of the slope containing the mining tunnel group under the action of dynamic and static load is studied, and the physical model is shown in FIG. 1. Figure 5 The step specifically includes:

[0057] Step 2.1: Based on the size of the prototype slope, a rigid model box is designed and manufactured according to the geometric similarity ratio. The model box is composed of steel plates and glass, which are connected by bolts. The interior is divided into a two-dimensional area (size specification: 1800mm×80.8mm×1000mm) and a three-dimensional area (size specification: 1800mm×778.4mm×1000mm) by steel plates, and is fixed to the shaking table table surface by using angle steel welding.

[0058] Step 2.2: Determine the similarity constants between the model and the prototype, and manufacture the physical model of the dynamic characteristics of the prototype slope according to the similarity theory. The similarity constants are shown in Table 1.

[0059] Table 1 Similarity constants of each parameter

[0060]

[0061] Step 2.3: Determine the type and ratio of the similar simulation material, use quartz sand, lime, gypsum, citric acid, water, mica sheet, and vaseline to make the model according to the actual slope rock layer properties. The physical and mechanical parameters of the model stratum are shown in Table 2.

[0062] Table 2 Physical and mechanical parameters of the model stratum

[0063]

[0064] When making, the model box bottom is paved with gravel to enhance friction and limit displacement, and 100mm thick polyethylene foam board is set on the front and back sides as a shock absorbing layer to simulate elastic support and reduce wave reflection. After mixing the materials according to the ratio, the model is assembled, and the base sandstone, coal layer, mud sandstone interbedded layer and loess are poured and compacted in order from bottom to top, with each 20mm layer thickness. The mixing ratio of the model layer is shown in Table 3.

[0065] Table 3 Mixing ratio of model layer

[0066]

[0067] Step 2.4: The model is made according to the actual slope rock layer properties, and the monitoring equipment is arranged during the pouring process. The monitoring equipment arrangement is shown in FIG. 2. Figure 6The soil pressure monitoring uses BW-0.5 type micro pressure box, and 3 monitoring lines with 12 measuring points are arranged along the slope direction to monitor the vertical stress of the support coal pillar roof and the horizontal stress of the upper rock mass; the strain monitoring uses 2.0 mm distributed strain sensing optical fiber, and multiple S-shaped optical fibers are arranged along the horizontal H1-H4 and vertical V1-V4 directions to monitor the strain distribution characteristics in the horizontal and vertical directions during the slope instability and failure stage.

[0068] Step 2.5: The model is rammed once every 20 mm layer thickness, and the basement sandstone, coal seam, mud sandstone interbedded layer and loess are sequentially poured from bottom to top; after the model is completed, it is cured for three days; after full curing, the two-dimensional and three-dimensional slope model steps are excavated synchronously, and the excavation interval of each step is 0.5 h, and after the completion of the entire excavation, it is placed until the internal stress field is stable; finally, six mining chambers with consistent specifications are excavated from the right boundary of the coal seam 200 mm apart, with a height, width and depth of 44 mm, 26.4 mm and 1200 mm respectively, and the excavation time interval of adjacent mining chambers is 1.6 h, the excavation rate is 125 mm / h, and the support coal pillar width is 40 mm. The soil pressure evolution during the excavation of the chamber is shown in FIG. 6. Figure 7 The vertical stress at monitoring lines 1-3 is shown in part a-c, and the horizontal stress at monitoring lines 1-3 is shown in part d-f.

[0069] Step 2.6: The slope is loaded with vibration waves; the acceleration time history with a main frequency of 5-10 Hz is obtained by filtering and baseline correction of the time history curve of the blasting vibration velocity at No. 1 monitoring point in the field based on SeismoSignal software; according to the similarity theory, the main frequency of the input wave is adjusted to 25-50 Hz, and the time length is compressed to 6 s; during the test, 34 micro-vibration waves (0.050g, BP1-BP34), 20 medium-vibration waves (0.072g, BP35-BP54) and 20 strong-vibration waves (0.120g, BP55-BP56) are sequentially applied until the model is destroyed; after each loading, a 0.05g, 30s flat Gaussian white noise is applied for frequency sweeping to obtain the dynamic characteristics of the model. The soil pressure evolution process during vibration is shown in FIG. 7. Figure 8 The vertical stress at monitoring line 2 is shown in part a, and the horizontal stress at monitoring line 2 is shown in part b; the distributed optical fiber sensor monitoring during the failure process shows obvious strain distribution characteristics, and the strain distribution measured by the optical fiber sensor is shown in FIG. 8. Figure 9 The strain distribution along the horizontal optical fibers H1-H4 is shown in parts a-d; the horizontal and vertical strain distributions on the central cross section are shown in parts e and f, respectively.

[0070] Step 3: The time-varying stability of the slope under dynamic and static loads is evaluated:

[0071] Step 3.1: Based on the acceleration data collected by the monitoring equipment, the collected acceleration data is processed using the tfestimate function in MATLAB to construct the absolute transfer function, and the imaginary part-frequency characteristic curve is extracted to identify the first-order natural frequency and damping ratio of the model. The initial natural frequency of the model slope was measured to be 26.8Hz before the first loading. This value is used as the benchmark for subsequent cumulative damage assessment. The slope damage degree D is calculated using the following formula:

[0072] ;

[0073] ;

[0074] In the formula, D represents the slope damage degree, and f0 and f represent the first-order natural frequencies of the soil and rock mass before and after vibration loading, respectively. This represents the rate of decrease in the natural frequency of the soil and rock mass.

[0075] The relationship between the damage degree (D) of the slope model and the number and intensity of blasting vibrations is shown in the attached figure. Figure 10 As shown, in the initial stage of the micro-vibration phase (PGA=0.024g), the value of D is negative, indicating that low-intensity vibration may have triggered a compaction effect on the slope, thus improving its stability. After entering the moderate vibration phase (PGA=0.072g), the value of D increases significantly, and microcracks have gradually developed and expanded into macro-cracks, leading to the formation of through-structure surfaces, thereby reducing slope stability. When entering the strong vibration phase (PGA=0.120g), the value of D increases dramatically, and the slope enters a critical instability state.

[0076] Step 3.2: Quantitatively evaluate the dynamic stability of the slope under blasting vibration load:

[0077] Based on the observed instability process, and with improvements and derivations made to the classical limit equilibrium theory, the dynamic time history analysis is combined with the Morgenstern-Price (MP) limit equilibrium method to obtain the time history expression for the slope safety factor under blasting vibration:

[0078] ;

[0079] in:

[0080] ;

[0081] In the formula: F s Here, E represents the dynamic time history safety factor of the slope, n is the total number of slices in the slice method, and E is the dynamic time history safety factor. i For the normal force between the blocks, ξ i H is the force transmission coefficient. i For the anti-slip force component, G i For the component of the downward force, α iis the dip angle of the i-th block bottom slip surface, λ is the inter-block force ratio coefficient, φ i is the internal friction angle of the i-th block bottom slip surface, W i is the self-weight of the i-th block, F iX is the horizontal blasting inertial force, F iZ is the vertical blasting inertial force, φ' is the effective internal friction angle, c i is the cohesion of the i-th block bottom slip surface, b i is the width of the i-th block bottom surface, m αi is the dip angle correction coefficient; calculated by the above formula, the dynamic safety factor changes with time as shown in the attached Figure 11

[0082] Step 4: Establish a two-dimensional numerical simulation model under the action of blasting vibration, and verify the behavior of the slope under different conditions through simulation calculation of two stages of initial static analysis and dynamic analysis.

[0083] Step 4.1: Determine the initial stress field distribution of the slope under the action of self-weight, create a geometric model in CAD, and import it into GeoStudio, mesh it into 2790 units and 2901 nodes, as shown in the attached Figure 12

[0084] Step 4.2: Use the QUAKE / W module to solve the initial stress field of the slope and the dynamic stress field at each time after applying horizontal and vertical blasting vibration, and determine the initial stress field distribution of the slope under the action of self-weight. The self-weight stress field cloud chart is shown in the attached Figure 13 x and the vertical stress σ y decreases with the increase of elevation, while the shear stress τ xy concentration phenomenon is observed at the slope toe and the mining chamber group area. Based on this initial stress state, the initial static safety factor calculated by the SLOPE / W module is 1.581, which shows that the slope is in a stable state under the initial state.

[0085] Step 4.3: Use the equivalent linear dynamic model, apply Y-direction displacement constraints on both sides of the model boundary conditions, apply X and Y direction displacement constraints at the bottom, and input horizontal and vertical blasting vibration at the same time. The vibration loading sequence is consistent with the shaking table test. Before each dynamic analysis, according to the slope damage degree coefficient D obtained from the shaking table test, the shear modulus and shear strength parameters (c, φ) of the slope are reduced accordingly, and the reduced parameters are used as the initial input of the next dynamic analysis, and the process is repeated until the slope fails. After applying the blasting vibration load on the basis of the initial stress field, the slope will produce dynamic response, and the horizontal relative displacement characteristics of the monitoring points at different elevations are monitored, and the horizontal relative displacement monitoring is shown in the attached Figure 14 ​​​The relative horizontal displacements of different elevation monitoring points (A5, A13, A14, A15, A16 and A17) under the first micro-vibration loading (BP01) show a left-right symmetric distribution characteristic, and increase with the increase of elevation, showing a typical "whip effect". During the transmission of the blasting vibration wave from the bottom to the top, lower horizontal displacement is generated at the lower part of the slope, while greater horizontal deformation is generated at the upper part, especially at the slope shoulder position, leading to the more prone to tensile failure in the slope shoulder area. Under the loading of BP01, the PGA amplification factor of the slope monitoring points gradually increases from the slope foot to the slope top; the PGA amplification factor of the slope body also shows an increasing trend from the low point to the high point. The PGA amplification factors at different vibration stages (BP01, BP34, BP54, BP55 and BP56) all increase with the increase of elevation, confirming that the horizontal acceleration has a significant elevation amplification effect on the slope surface and slope body.

[0086] Step 4.4: By analyzing the X-Y shear strain of the slope foot monitoring point and the peak value appearance time of the horizontal displacement of the slope top monitoring point, the time sequence characteristics of slope instability and failure are determined, as shown in FIG. 4b. Figure 15 The minimum average safety factor is used to evaluate the stability of the two-dimensional slope numerical model, and the cumulative damage effect under the action of multiple blasting is explored. The time history curve of the safety factor of the slope is shown in FIG. 4c. Figure 16 The calculation results show that the stability of the slope decreases significantly with the increase of the number and intensity of blasting vibration, and the decrease rate gradually increases, reflecting the cumulative damage effect under the action of multiple blasting. The minimum average safety factor at the initial stage (BP1) and the final stage (BP34) of micro-vibration is 1.571 and 1.459 respectively, which is reduced by 0.63% and 7.71% respectively compared with the initial state, and the slope is still in a stable state. At the end of the medium vibration stage (BP54), the minimum average safety factor decreases to 1.091, with a decrease of 30.9%, and the slope enters a basically stable state; in the strong vibration stage, the minimum average safety factor under the action of BP55 is 1.021, with a decrease of 35.4%, and the slope is close to the limit equilibrium state; after the action of BP56, the minimum average safety factor is 0.988, with a cumulative decrease of 37.5%, and the slope is in an unstable state. This evolution process clearly reveals the progressive damage mechanism of the cumulative effect of blasting vibration on the stability of the slope.

[0087] Step 4.5: Finally, the minimum average safety factor is used to evaluate the stability of the two-dimensional slope numerical model, and the cumulative damage effect under the action of multiple blasting is explored.

[0088] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for evaluating the time-varying stability of a slope containing a group of mining tunnels under the action of blasting vibration, characterized in that: The evaluation steps include the following: Step 1: arranging monitoring points on the toe of the open-pit end slope and different elevation steps, collecting blasting data and studying the dynamic response characteristics in the blasting operation, and then selecting the final physical and mechanical parameters of each rock layer according to the production data of the mine area; Step 2: constructing a physical model of the shaking table test according to the actual spatial form characteristics of the slope, and studying the dynamic instability evolution mechanism of the slope containing the mining tunnel group under the action of dynamic and static loads based on the constructed physical model; Step 3: evaluating the time-varying stability of the slope under the action of dynamic and static loads; Step 4: establishing a two-dimensional numerical simulation model under the action of blasting vibration, and respectively simulating and calculating the initial static analysis and dynamic analysis two stages.

2. The method according to claim 1, characterized in that: The specific method of step 1 is: Step 1.1: using a vibration meter to arrange monitoring points on the toe of the open-pit end slope and different elevation steps, and collecting the horizontal and vertical direction velocity time history data of each monitoring point during the blasting operation; Step 1.2: based on the vibration velocity data of each direction of the monitoring points, an optimized Sadaovsky formula is used to establish a prediction model of the global peak vibration velocity.

3. The method according to claim 2, characterized in that: The specific method of step 2 is: Step 2.1: based on the size of the prototype slope, a rigid model box is designed and made according to the geometric similarity ratio; Step 2.2: determine the similarity constant of the physical model and the actual slope form, and produce a physical model that can simulate the dynamic characteristics of the actual slope according to the similarity theory; Step 2.3: determine the type and ratio of the similar simulation materials; Step 2.4: according to the actual slope rock layer properties, the model is made by proportioning, and in the model pouring process, soil pressure cells, distributed strain sensing optical fibers, non-contact three-dimensional optical photogrammetry system monitoring equipment are simultaneously laid; Step 2.5: the model is poured and rammed once every 20mm layer thickness, from bottom to top, the base sandstone, coal seam, mud sandstone interbedded, loess are sequentially poured, after the model is completed, maintenance is carried out, and the two-dimensional and three-dimensional slope model steps are excavated and mined simultaneously; Step 2.6: based on the blasting vibration velocity time history curve of the field monitoring point, the vibration wave frequency of the physical model is determined according to the similarity theory, and it is loaded.

4. The method according to claim 3, characterized in that: The specific method of step 3 is: Step 3.1: according to the acceleration data collected by the monitoring equipment, the tfestimate function in MATLAB is used to process the collected acceleration data, the absolute transfer function is constructed, and the imaginary part-frequency characteristic curve is extracted to identify the first-order natural frequency and damping ratio of the model, and the slope damage degree is calculated; Based on the change of the first-order natural frequency, the slope damage degree D is calculated by the following formula: ； ； In the formula, D is the slope damage degree, f0 and f respectively represent the first natural frequency of the rock-soil body before and after vibration loading, is the reduction rate of the natural frequency of the rock-soil body; Step 3.2: quantitatively evaluating the dynamic stability of the slope under the action of blasting vibration load, calculating the dynamic time history safety factor of the slope under blasting vibration, and the calculation formula is: ； In the formula: F s is the dynamic time-history safety factor of the slope, n is the total number of slices in the slice method, E i is the normal force between slices, ξ i is the force transmission coefficient, H i is the anti-sliding force component, G i is the downslide force component.

5. The method according to claim 4, wherein the method is characterized in that: The specific method of step 4 is: Step 4.1: determine the initial stress field distribution of the slope under the action of self-weight; Step 4.2: by constraining the X-direction displacement of the two sides of the model and the X, Y-direction displacement of the bottom, the initial static equilibrium state of the slope under the action of self-weight is calculated under the framework of linear elastic constitutive model; Step 4.3: Using the equivalent linear dynamic model, Y-direction displacement constraints are applied on both sides of the model boundary conditions, X and Y direction displacement constraints are applied on the bottom, and horizontal and vertical blasting vibration waves are input simultaneously. This process is iterated until the slope fails and is destroyed. Step 4.4: By analyzing the X-Y shear strain at the slope toe monitoring point and the peak value appearance time of the horizontal displacement at the slope top monitoring point, the time sequence characteristics of the slope instability and failure are determined. Step 4.5: The minimum average safety factor is used to evaluate the stability of the two-dimensional slope numerical model, and the cumulative damage effect under multiple blasting actions is explored.

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