A method for establishing a dynamic cumulative damage constitutive model of multi-joint rock mass under cyclic impact

Abstract

The application discloses a kind of establishment methods of multi-joint rock mass dynamic cumulative damage constitutive model under cyclic impact, comprising the following steps: S1, field rock sample collection and pretreatment, for the geological characteristics of open-pit mine multi-joint rock mass, collect the rock sample of different joint dip angle, joint development degree, process and maintain sample, prepare standard test piece that meets the requirement of split hopkinson pressure bar dynamic compression test;S2, carry out cyclic impact indoor test, using split hopkinson pressure bar system to different joint dip angle standard test piece cyclic impact load, determine the stress-strain relationship of test piece under different cyclic impact times, peak strength, failure mode, obtain the basic parameters of multi-joint rock mass dynamics.This model considers the influence of multiple factors, fits the engineering practice, has high prediction accuracy, the method is easy to popularize, can support mine blasting parameter optimization and slope protection, adapt to various open-pit mine working conditions.

Description

Technical Field

[0001] This invention relates to the field of blasting engineering technology, and in particular to a method for establishing a dynamic cumulative damage constitutive model of multi-jointed rock mass under cyclic impact. Background Technology

[0002] Blasting technology is one of the core technologies in open-pit mining. The vibration effect generated by cyclic blasting causes continuous dynamic impact on the rock mass of mine slopes, triggering the initiation, propagation, and connection of joints, resulting in cumulative damage. This can ultimately lead to slope instability, becoming a major hidden danger to the safe production of open-pit mines. Multi-jointed rock masses, as a common geological body in open-pit mine slopes, exhibit complex dynamic nonlinear characteristics due to the dual influence of joint dip angle, joint development degree, and cyclic impact loads. Therefore, establishing a constitutive model that can accurately describe the dynamic cumulative damage evolution of multi-jointed rock masses under cyclic impact is crucial for predicting slope stability and optimizing blasting parameters.

[0003] Currently, existing research on rock mass damage constitutive models largely focuses on homogeneous rock masses under single impact or static loading, with a lack of research on dynamic cumulative damage constitutive models for multi-jointed rock masses under cyclic impact. While some studies have constructed cumulative damage constitutive models, they have not fully considered the influence of joint dip angles on the dynamic mechanical properties of the rock mass, or have failed to integrate the models with the cyclic blasting conditions in actual mines, resulting in poor engineering adaptability and low prediction accuracy. Furthermore, existing models largely rely on laboratory test data, lacking fitting and correction with measured slope data from actual sites, and thus cannot accurately reflect the damage evolution of rock masses under actual geological conditions in mines, making them difficult to directly apply to slope stability assessment under cyclic blasting vibrations in open-pit mines.

[0004] Furthermore, in open-pit mine engineering practice, the load characteristics of cyclic blasting vibrations and the joint distribution characteristics of rock masses differ from those in laboratory tests. Existing constitutive models do not consider the attenuation effect of the number of cyclic impacts and the influence of on-site geological and topographical conditions, resulting in significant deviations between the numerical simulation results obtained using the models and actual field conditions. This fails to provide reliable theoretical support for optimizing mine blasting parameters and slope protection. Therefore, developing a method for establishing a dynamic cumulative damage constitutive model for multi-jointed rock masses that combines laboratory cyclic impact tests, field measured data, and numerical simulations, and considers key factors such as joint dip angle and the number of cyclic impacts, has become an urgent technical problem to be solved in the field of open-pit mine blasting engineering. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for establishing a dynamic cumulative damage constitutive model for multi-jointed rock masses under cyclic impact.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for establishing a dynamic cumulative damage constitutive model for multi-jointed rock masses under cyclic impact includes the following steps: S1. On-site rock sample collection and pretreatment: In view of the geological characteristics of multi-jointed rock mass in open-pit mines, rock mass samples with different joint dip angles and joint development degrees are collected, and the samples are processed and cured to prepare standard specimens that meet the requirements of the split Hopkinson bar dynamic compression test. S2. Conduct cyclic impact laboratory tests, and use a split Hopkinson bar system to apply cyclic impact loads to standard specimens with different joint dip angles. Determine the stress-strain relationship, peak strength, and failure mode of the specimens under different cyclic impact cycles, and obtain the basic dynamic mechanical parameters of multi-jointed rock mass. S3. Define the cumulative damage variable. Based on the theory of damage mechanics, with the reduction of the effective bearing area of ​​the rock mass as the core, and combined with the plastic deformation and joint expansion characteristics of the rock mass under cyclic impact, define the cumulative damage variable of multi-jointed rock mass. This damage variable is a dimensionless parameter between zero and one. A value of zero indicates that the rock mass is undamaged, and a value of one indicates that the rock mass is completely destroyed. S4. Construct the initial constitutive equation, combine the joint crack propagation theory in fracture mechanics, introduce the joint dip angle influence coefficient and the cyclic impact number attenuation coefficient, couple the cumulative damage variable to the dynamic elastic constitutive relation of the rock mass, and establish the initial constitutive equation for dynamic cumulative damage of multi-jointed rock mass under cyclic impact. S5. Establish a numerical model of the slope. Based on the geological survey data of the mine and the elevation point cloud data of the UAV, use Rhino software and Gridle software to construct a three-dimensional geometric model of the slope and convert it into a calculation model suitable for fast Lagrange analysis three-dimensional software. S6. Model parameter fitting and correction: Through the secondary development of the rapid Lagrange analysis 3D software, the initial constitutive equation of step S4 is embedded into the numerical model, the cyclic blasting load consistent with the field is applied, key monitoring points are set, the numerical simulation results are fitted with the measured data of slope displacement and crack development on site, and the model parameters such as joint dip angle influence coefficient and cyclic impact attenuation coefficient are corrected to obtain the optimized constitutive model. S7. Model verification and accuracy assessment: Select another dangerous slope in the mine as the verification object, apply the optimized constitutive model to the simulation of cyclic blasting vibration response of the slope, compare the simulation results with the field monitoring data, and evaluate the prediction accuracy of the model. If the accuracy does not reach the preset threshold, return to step S6 to readjust the parameters until the engineering requirements are met.

[0007] Preferably, in step S1, the standard specimen is a cylindrical specimen with a diameter of 50 mm and a height of 25 mm, and the joint dip angle is set to 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees. The degree of joint development is divided into three levels: weak development, medium development and strong development according to the actual situation on site.

[0008] Preferably, in step S2, the cyclic impact load parameters of the split Hopkinson bar system are matched with the stress wave parameters of the cyclic blasting vibration at the mine site. The impact air pressure is adjusted according to the uniaxial compressive strength of the rock mass. The number of cyclic impacts is one to twenty, and the interval between each impact is five to ten seconds. During the test, the crack propagation and failure process of the specimen is recorded by a high-speed camera.

[0009] Preferably, in step S3, the cumulative damage variable is determined based on the changes in the effective bearing area and dynamic elastic modulus of the rock mass. Using the initial effective bearing area and initial dynamic elastic modulus of the rock mass as a benchmark, the cumulative damage degree of the rock mass is quantified by the ratio of the effective bearing area and dynamic elastic modulus of the rock mass after cyclic impact to the initial value.

[0010] Preferably, in step S4, the joint dip angle influence coefficient is obtained by fitting the joint dip angle and the peak strength of the rock mass. This coefficient fluctuates regularly with the change of joint dip angle, and can accurately reflect the influence of different joint dip angles on the dynamic mechanical properties of the rock mass. The cyclic impact number decay coefficient is an exponential decay relationship, which gradually decreases with the increase of the cyclic impact number, reflecting the gradual decay characteristic of the rock mass mechanical properties with the increase of the impact number.

[0011] Preferably, in step S4, the initial constitutive equation for dynamic cumulative damage of multi-jointed rock mass under cyclic impact combines the joint dip angle influence coefficient, the cyclic impact number attenuation coefficient, and the cumulative damage variable, and correlates the dynamic stress and dynamic strain of the rock mass, which can reflect the dynamic mechanical response of the rock mass under the coupling effect of multiple factors.

[0012] Preferably, in step S5, the acquisition accuracy of the UAV elevation point cloud data is not less than 0.1 meters, and the mesh division accuracy of the three-dimensional geometric model is set according to the differences between the key and non-key areas of the slope. The free face of the slope and the joint development area adopt a fine mesh with a mesh size of 0.5 meters to 1 meter, while the deep area of ​​the slope adopts a conventional mesh with a mesh size of 2 meters to 5 meters.

[0013] Preferably, in step S6, the secondary development of the rapid Lagrange analysis 3D software uses a computer programming language to write constitutive model subroutines. The interface between the subroutines and the software is realized through the software's dedicated scripting language. The cyclic blasting load is converted into an equivalent stress load based on the acceleration time history curve of the on-site blasting vibration monitoring and applied to the model. The parameter fitting adopts the least squares method, with the goal of minimizing the root mean square error between the on-site monitored slope displacement value and the numerical simulation displacement value, and corrects the values ​​of the joint dip angle influence coefficient and the cyclic impact attenuation coefficient.

[0014] Preferably, in step S7, the preset model prediction accuracy threshold is a root mean square error of no more than 10%. If the root mean square error between the simulation result and the field monitoring data exceeds 10%, the decay rate correlation constant and the experimental fitting correlation constant are adjusted, and numerical simulation and data fitting are performed again.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. The constitutive model established in this invention fully considers the influence of joint dip angle and cyclic impact number on the dynamic mechanical properties of multi-jointed rock mass. It introduces the joint dip angle influence coefficient and the cyclic impact number attenuation coefficient, which solves the technical problem that the existing model does not consider the coupling of multiple factors and cannot reflect the anisotropy of rock mass. It can accurately describe the damage evolution and mechanical response law of multi-jointed rock mass under cyclic impact. 2. This invention constructs and corrects the model by combining indoor cyclic impact tests with field measured data. The model is connected with the slope numerical model through secondary development of rapid Lagrange analysis 3D software. The least squares method is used to fit and correct the model parameters, making the model more consistent with the actual mining engineering, with high prediction accuracy and root mean square error of no more than 10%, which is far superior to the existing models established by pure indoor tests. 3. The method of this invention has a clear process and is highly operable. The split Hopkinson bar test system, UAV technology, and rapid Lagrange analysis three-dimensional numerical simulation software used are all conventional technologies and equipment in the field of mining engineering, which are easy to promote and apply in mining enterprises. The model parameter correction process is simple and can be flexibly adjusted according to the geological characteristics and blasting conditions of different mines. 4. The constitutive model established by this invention can be directly embedded into mainstream geotechnical engineering numerical simulation software such as rapid Lagrange analysis 3D, and used for stability prediction of slopes under cyclic blasting vibration in open-pit mines. It can accurately calculate the displacement changes and stability coefficient decay process of slopes under different cyclic blasting times, providing reliable theoretical support for mine blasting parameter optimization and slope protection design, effectively reducing the harm of cyclic blasting to slopes, and achieving the unity of mine economic benefits and safe production. 5. The method of this invention is not only applicable to jointed rock masses in open-pit coal mines, but can also be adapted to the geological and blasting conditions of other open-pit mines such as metal mines and quarries by adjusting parameters such as the joint dip angle influence coefficient and the cyclic impact attenuation coefficient. It has wide engineering applicability and promotion value. Attached Figure Description

[0016] Figure 1 This is a logic diagram of a method for establishing a dynamic cumulative damage constitutive model of multi-jointed rock mass under cyclic impact proposed in this invention. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] Reference Figure 1 A method for establishing a dynamic cumulative damage constitutive model for multi-jointed rock masses under cyclic impact includes the following steps: S1. On-site rock sample collection and pretreatment: In view of the geological characteristics of multi-jointed rock mass in open-pit mines, rock mass samples with different joint dip angles and joint development degrees are collected, and the samples are processed and cured to prepare standard specimens that meet the requirements of the split Hopkinson bar dynamic compression test. S2. Conduct cyclic impact laboratory tests, and use a split Hopkinson bar system to apply cyclic impact loads to standard specimens with different joint dip angles. Determine the stress-strain relationship, peak strength, and failure mode of the specimens under different cyclic impact cycles, and obtain the basic dynamic mechanical parameters of multi-jointed rock mass. S3. Define the cumulative damage variable. Based on the theory of damage mechanics, with the reduction of the effective bearing area of ​​the rock mass as the core, and combined with the plastic deformation and joint expansion characteristics of the rock mass under cyclic impact, define the cumulative damage variable of multi-jointed rock mass. This damage variable is a dimensionless parameter between zero and one. A value of zero indicates that the rock mass is undamaged, and a value of one indicates that the rock mass is completely destroyed. S4. Construct the initial constitutive equation, combine the joint crack propagation theory in fracture mechanics, introduce the joint dip angle influence coefficient and the cyclic impact number attenuation coefficient, couple the cumulative damage variable to the dynamic elastic constitutive relation of the rock mass, and establish the initial constitutive equation for dynamic cumulative damage of multi-jointed rock mass under cyclic impact. S5. Establish a numerical model of the slope. Based on the geological survey data of the mine and the elevation point cloud data of the UAV, use Rhino software and Gridle software to construct a three-dimensional geometric model of the slope and convert it into a calculation model suitable for fast Lagrange analysis three-dimensional software. S6. Model parameter fitting and correction: Through the secondary development of the rapid Lagrange analysis 3D software, the initial constitutive equation of step S4 is embedded into the numerical model, the cyclic blasting load consistent with the field is applied, key monitoring points are set, the numerical simulation results are fitted with the measured data of slope displacement and crack development on site, and the model parameters such as joint dip angle influence coefficient and cyclic impact attenuation coefficient are corrected to obtain the optimized constitutive model. S7. Model verification and accuracy assessment: Select another dangerous slope in the mine as the verification object, apply the optimized constitutive model to the simulation of cyclic blasting vibration response of the slope, compare the simulation results with the field monitoring data, and evaluate the prediction accuracy of the model. If the accuracy does not reach the preset threshold, return to step S6 to readjust the parameters until the engineering requirements are met.

[0019] In step S1, the standard specimen is a cylindrical specimen with a diameter of 50 mm and a height of 25 mm. The joint dip angle is set to 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees. The degree of joint development is divided into three levels: weak development, moderate development and strong development according to the actual situation on site.

[0020] In step S2, the cyclic impact load parameters of the split Hopkinson bar system are matched with the stress wave parameters of the cyclic blasting vibration at the mine site. The impact air pressure is adjusted according to the uniaxial compressive strength of the rock mass. The number of cyclic impacts is one to twenty, and the interval between each impact is five to ten seconds. During the test, the crack propagation and failure process of the specimen is recorded by a high-speed camera.

[0021] In step S3, the cumulative damage variable is determined based on the changes in the effective bearing area and dynamic elastic modulus of the rock mass. Using the initial effective bearing area and initial dynamic elastic modulus of the rock mass as a benchmark, the cumulative damage degree of the rock mass is quantified by the ratio of the effective bearing area and dynamic elastic modulus of the rock mass after cyclic impact to the initial value.

[0022] In step S4, the joint dip angle influence coefficient is obtained by fitting the joint dip angle and the peak strength of the rock mass. This coefficient shows a regular fluctuation with the change of joint dip angle, which can accurately reflect the influence of different joint dip angles on the dynamic mechanical properties of the rock mass. The cyclic impact number decay coefficient has an exponential decay relationship and gradually decreases with the increase of the cyclic impact number, reflecting the gradual decay characteristics of the rock mass mechanical properties with the increase of the impact number.

[0023] In step S4, the initial constitutive equation for the dynamic cumulative damage of multi-jointed rock mass under cyclic impact combines the joint dip angle influence coefficient, the cyclic impact number attenuation coefficient, and the cumulative damage variable, and correlates the dynamic stress and dynamic strain of the rock mass, which can reflect the dynamic mechanical response of the rock mass under the coupling of multiple factors.

[0024] In step S5, the acquisition accuracy of the UAV elevation point cloud data is no less than 0.1 meters. The mesh division accuracy of the three-dimensional geometric model is set according to the differences between the key and non-key areas of the slope. The free face and joint development area of ​​the slope adopt fine mesh with a mesh size of 0.5 to 1 meter. The deep area of ​​the slope adopts conventional mesh with a mesh size of 2 to 5 meters.

[0025] In step S6, the secondary development of the rapid Lagrange analysis 3D software uses a computer programming language to write constitutive model subroutines. The subroutines are interfaced with the software through the software's dedicated scripting language. The cyclic blasting load is converted into an equivalent stress load based on the acceleration time history curve of the on-site blasting vibration monitoring and applied to the model. The parameter fitting adopts the least squares method, with the goal of minimizing the root mean square error between the on-site monitored slope displacement value and the numerical simulation displacement value, and correcting the values ​​of the joint dip angle influence coefficient and the cyclic impact attenuation coefficient.

[0026] In step S7, the preset model prediction accuracy threshold is that the root mean square error is no more than 10%. If the root mean square error between the simulation result and the field monitoring data exceeds 10%, the decay rate correlation constant and the experimental fitting correlation constant are adjusted, and numerical simulation and data fitting are performed again.

[0027] Working principle: The invented constitutive model for dynamic cumulative damage in multi-jointed rock masses under cyclic impact is based on damage mechanics and fracture mechanics. It combines indoor cyclic impact tests using a split Hopkinson bar system with field measurement data from mines to accurately model the damage evolution of multi-jointed rock masses under cyclic blasting vibration. Its core working principle is as follows: The principle of damage variable quantification: The reduction of the effective bearing area of ​​the rock mass and the decay of the dynamic elastic modulus are used as the basis for quantifying cumulative damage. The damage variable is defined as the ratio of the mechanical parameters of the rock mass in its initial state to that in its state after cyclic impact, so as to realize the dimensionless nature of the damage degree and accurately reflect the damage evolution process of the rock mass under cyclic impact. The coupling principle of key influencing factors: The joint dip angle influence coefficient and the cyclic impact number decay coefficient are introduced to quantify the anisotropic influence of joint dip angle on the dynamic mechanical properties of rock mass and the gradual decay influence of cyclic impact number on the mechanical properties of rock mass, respectively. The two coefficients are coupled together with the damage variable into the dynamic elastic constitutive relation of rock mass to make up for the deficiency of existing models that do not consider the coupling of multiple factors. The principle of integrating indoor test data with field data: The basic dynamic mechanical parameters of multi-jointed rock masses are obtained through the split Hopkinson bar indoor test, the initial constitutive equation is constructed, and then the model parameters are fitted and corrected using the field measured data of the mine slope, so as to achieve deep integration of indoor test data and field engineering reality and improve the engineering adaptability of the model. Verification and optimization principle of numerical simulation: The constitutive model is embedded into the three-dimensional slope numerical model of fast Lagrange analysis, and the same cyclic blasting load as in the field is applied. By comparing and analyzing the numerical simulation results with the field monitoring data, the model parameters are repeatedly corrected to ensure that the model can accurately reflect the dynamic damage law of cyclic blasting vibration on multi-jointed rock mass under the actual geological conditions of the mine.

[0028] The constitutive model established in this invention essentially combines the micro-joint extension of rock mass with macro-mechanical response, and integrates indoor experimental laws with field engineering conditions to achieve a quantitative description of the dynamic cumulative damage of multi-jointed rock mass under cyclic impact, providing a reliable theoretical model for slope stability prediction.

[0029] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for establishing a dynamic cumulative damage constitutive model for multi-jointed rock masses under cyclic impact, characterized in that, Includes the following steps: S1. On-site rock sample collection and pretreatment: In view of the geological characteristics of multi-jointed rock mass in open-pit mines, rock mass samples with different joint dip angles and joint development degrees are collected, and the samples are processed and cured to prepare standard specimens that meet the requirements of the split Hopkinson bar dynamic compression test. S2. Conduct cyclic impact laboratory tests, and use a split Hopkinson bar system to apply cyclic impact loads to standard specimens with different joint dip angles. Determine the stress-strain relationship, peak strength, and failure mode of the specimens under different cyclic impact cycles, and obtain the basic dynamic mechanical parameters of multi-jointed rock mass. S3. Define the cumulative damage variable. Based on the theory of damage mechanics, with the reduction of the effective bearing area of ​​the rock mass as the core, and combined with the plastic deformation and joint expansion characteristics of the rock mass under cyclic impact, define the cumulative damage variable of multi-jointed rock mass. This damage variable is a dimensionless parameter between zero and one. A value of zero indicates that the rock mass is undamaged, and a value of one indicates that the rock mass is completely destroyed. S4. Construct the initial constitutive equation, combine the joint crack propagation theory in fracture mechanics, introduce the joint dip angle influence coefficient and the cyclic impact number attenuation coefficient, couple the cumulative damage variable to the dynamic elastic constitutive relation of the rock mass, and establish the initial constitutive equation for dynamic cumulative damage of multi-jointed rock mass under cyclic impact. S5. Establish a numerical model of the slope. Based on the geological survey data of the mine and the elevation point cloud data of the UAV, use Rhino software and Gridle software to construct a three-dimensional geometric model of the slope and convert it into a calculation model suitable for fast Lagrange analysis three-dimensional software. S6. Model parameter fitting and correction: Through the secondary development of the rapid Lagrange analysis 3D software, the initial constitutive equation of step S4 is embedded into the numerical model, the cyclic blasting load consistent with the field is applied, key monitoring points are set, the numerical simulation results are fitted with the measured data of slope displacement and crack development on site, and the model parameters such as joint dip angle influence coefficient and cyclic impact attenuation coefficient are corrected to obtain the optimized constitutive model. S7. Model verification and accuracy assessment: Select another dangerous slope in the mine as the verification object, apply the optimized constitutive model to the simulation of cyclic blasting vibration response of the slope, compare the simulation results with the field monitoring data, and evaluate the prediction accuracy of the model. If the accuracy does not reach the preset threshold, return to step S6 to readjust the parameters until the engineering requirements are met.

2. The method for establishing a dynamic cumulative damage constitutive model of multi-jointed rock mass under cyclic impact as described in claim 1, characterized in that, In step S1, the standard specimen is a cylindrical specimen with a diameter of 50 mm and a height of 25 mm. The joint dip angle is set to 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees. The degree of joint development is divided into three levels: weak development, moderate development and strong development according to the actual situation on site.

3. The method for establishing a dynamic cumulative damage constitutive model of multi-jointed rock mass under cyclic impact as described in claim 1, characterized in that, In step S2, the cyclic impact load parameters of the split Hopkinson bar system are matched with the stress wave parameters of the cyclic blasting vibration at the mine site. The impact air pressure is adjusted according to the uniaxial compressive strength of the rock mass. The number of cyclic impacts is one to twenty, and the interval between each impact is five to ten seconds. During the test, the crack propagation and failure process of the specimen is recorded by a high-speed camera.

4. The method for establishing a dynamic cumulative damage constitutive model of multi-jointed rock mass under cyclic impact as described in claim 1, characterized in that, In step S3, the cumulative damage variable is determined based on the changes in the effective bearing area and dynamic elastic modulus of the rock mass. Taking the initial effective bearing area and initial dynamic elastic modulus of the rock mass as a benchmark, the cumulative damage degree of the rock mass is quantified by the ratio of the effective bearing area and dynamic elastic modulus of the rock mass after cyclic impact to the initial value.

5. The method for establishing a dynamic cumulative damage constitutive model of multi-jointed rock mass under cyclic impact as described in claim 1, characterized in that, In step S4, the joint dip angle influence coefficient is obtained by fitting the relationship between the joint dip angle and the peak strength of the rock mass. This coefficient shows a regular fluctuation with the change of the joint dip angle, which can accurately reflect the influence of different joint dip angles on the dynamic mechanical properties of the rock mass. The cyclic impact number decay coefficient has an exponential decay relationship and gradually decreases with the increase of the cyclic impact number, reflecting the gradual decay characteristic of the rock mass mechanical properties with the increase of the impact number.

6. The method for establishing a dynamic cumulative damage constitutive model of multi-jointed rock mass under cyclic impact as described in claim 1, characterized in that, In step S4, the initial constitutive equation for dynamic cumulative damage of multi-jointed rock mass under cyclic impact combines the joint dip angle influence coefficient, the cyclic impact number attenuation coefficient, and the cumulative damage variable, and correlates the dynamic stress and dynamic strain of the rock mass, which can reflect the dynamic mechanical response of the rock mass under the coupling effect of multiple factors.

7. The method for establishing a dynamic cumulative damage constitutive model of multi-jointed rock mass under cyclic impact as described in claim 1, characterized in that, In step S5, the acquisition accuracy of the UAV elevation point cloud data is not less than 0.1 meters. The mesh division accuracy of the three-dimensional geometric model is set according to the differences between the key and non-key areas of the slope. The free face and joint development area of ​​the slope adopt a fine mesh with a mesh size of 0.5 meters to 1 meter. The deep area of ​​the slope adopts a conventional mesh with a mesh size of 2 meters to 5 meters.

8. The method for establishing a dynamic cumulative damage constitutive model of multi-jointed rock mass under cyclic impact as described in claim 1, characterized in that, In step S6, the secondary development of the rapid Lagrange analysis 3D software uses a computer programming language to write constitutive model subroutines. The interface between the subroutines and the software is realized through the software's dedicated scripting language. The cyclic blasting load is converted into an equivalent stress load based on the acceleration time history curve of the on-site blasting vibration monitoring and applied to the model. The parameter fitting adopts the least squares method, with the goal of minimizing the root mean square error between the on-site monitored slope displacement value and the numerical simulation displacement value, and corrects the values ​​of the joint dip angle influence coefficient and the cyclic impact attenuation coefficient.

9. The method for establishing a dynamic cumulative damage constitutive model of multi-jointed rock mass under cyclic impact as described in claim 1, characterized in that, In step S7, the preset model prediction accuracy threshold is that the root mean square error is no more than 10%. If the root mean square error between the simulation result and the field monitoring data exceeds 10%, the decay rate correlation constant and the experimental fitting correlation constant are adjusted, and numerical simulation and data fitting are performed again.

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