Three-dimensional reconstruction of discontinuous fractured media in rock slopes and stability assessment method

Abstract

The present invention relates to the technical field of rock slope stability assessment, and discloses a method for reconstruction and stability assessment of three-dimensional discontinuous broken media in rock slopes, comprising the following steps: S1, detecting the rock structure composition inside the slope, and determining the overall spatial characteristics and mechanical parameters of the discontinuous broken media inside the rock layer; S2, constructing a three-dimensional slope finite element model; S3, constructing a numerical model of an unfavorable geological rock slope; S4, using a strength reduction method to perform stability analysis and calculation on the constructed numerical model of an unfavorable geological rock slope; S5, displaying a numerical model of an unfavorable geological rock slope containing a spatial discontinuous broken medium and a corresponding slope instability failure mode, and conducting a stability assessment on the unfavorable geological rock slope. The present invention solves the technical problem that the prior art is difficult to precisely characterize the real spatial morphology of the discontinuous broken media inside the rock layer, and thus is unable to effectively assess the safe and stable state of a rock slope containing a spatial discontinuous broken medium.

Description

Technical Field

[0001] The invention relates to the technical field of rock slope stability assessment, and in particular to a three-dimensional discontinuous broken medium reconstruction and stability assessment method for a rock slope. Background Art

[0002] Large-scale water conservancy and hydropower projects have high requirements for geographical location. Most of them are located in deep mountain canyon areas. The geological structure of the rock strata is extremely complex, and there are usually a large number of discontinuous fracture zones inside. Affected by fault zones and long-term geological evolution, discontinuous fracture zones usually have a certain tendency. Studies have shown that this plays a controlling role in the safety and stability of high and steep rock slopes, and large landslides caused by this are common. This type of giant landslide has the significant characteristics of complex disaster mechanism, high concealment, and strong destructiveness. It seriously threatens the safety of engineering parts such as dams, large underground caverns, and reservoirs. During the construction period, it will also have a certain impact on the quality, progress, and investment of the project.

[0003] For the stability and safety assessment of this type of rock slope with adverse geology, there are few existing studies that can provide a relatively realistic inversion of the discontinuous crushed media inside the rock slope. Most of the existing studies are based on a two-dimensional model with a single boundary condition for analysis. The assumptions are too simplified and seriously deviate from the actual geological conditions. The calculation results are difficult to accurately assess the stability of this type of slope, and there is still great uncertainty in the actual instability mechanism.

[0004] Based on this, existing methods are difficult to solve this type of problem, and it is urgent to use advanced technology to accurately characterize the spatial existence form of discontinuous broken media inside rock slopes. This has important engineering practical significance for clarifying the instability mechanism of such slopes and proposing targeted and effective reinforcement and comprehensive prevention and control plans. Summary of the invention

[0005] In order to solve the current technical problems, the main purpose of the present invention is to provide a method for reconstructing and evaluating the stability of three-dimensional discontinuous crushed media in rock slopes, thereby solving the technical problem that the existing technology is difficult to accurately characterize the real spatial morphology of discontinuous crushed media inside the rock layer, and thus cannot effectively evaluate the safety and stability of rock slopes containing spatial discontinuous crushed media.

[0006] The technical solution adopted by the present invention is: a method for reconstructing and evaluating the stability of discontinuous broken media in a three-dimensional rock slope, comprising the following steps:

[0007] S1. Within the scope of the site of the bad geological rock slope, detect the rock structure composition inside the slope and determine the overall spatial characteristics and mechanical parameters of the discontinuous broken medium inside the slope;

[0008] S2. According to the geometric dimensions of the slope area, a three-dimensional slope finite element model is constructed using finite element analysis software;

[0009] S3. Use the random field method to precisely characterize the discontinuous fractured medium in the rock slope and construct a numerical model of the rock slope with poor geology;

[0010] S3-1. Generate a three-dimensional random number matrix that obeys a standard normal distribution;

[0011] S3-2, rotating the three-dimensional slope finite element model according to the horizontal inclination of the discontinuous crushing medium;

[0012] S3-3, overall scaling and rotating the node coordinates of the three-dimensional slope finite element model to determine the relative positions of the nodes in space;

[0013] S3-4, generating random values ​​with spatial correlation and obeying standard normal distribution at each node;

[0014] S3-5. Select several range sub-intervals consisting of upper and lower bounds on the horizontal coordinate system of the probability density function of the standard normal distribution;

[0015] S3-6, determine the type of medium;

[0016] S4. Use the strength reduction method to perform stability analysis and calculation on the constructed numerical model of the bad geological rock slope;

[0017] S5. Through the calculation results, the numerical model of the unfavorable geological rock slope containing spatially discontinuous broken media and the corresponding slope instability failure mode are demonstrated, and the stability of the unfavorable geological rock slope is evaluated.

[0018] In step S1, the rock structure inside the slope is detected by electrical sounding geophysical method, the physical and mechanical properties of the crushing medium are determined by in-situ or indoor geotechnical test methods, the overall spatial characteristics and mechanical parameters of the discontinuous crushing medium are determined, and the spatial morphology of the discontinuous crushing medium inside the slope is obtained by geological sketching.

[0019] In step S1, the overall spatial characteristics include average length, average thickness, horizontal inclination and relative density; and the mechanical parameters include relative strength.

[0020] In step S2, a three-dimensional slope finite element model is established by using the CAE function module in the finite element analysis software ABAQUS, setting the constitutive model, elastic parameters and displacement boundary conditions, establishing a ground stress equilibrium analysis step and a static analysis step, and using the free meshing technology to divide the three-dimensional slope finite element model unit grid using a three-dimensional eight-node hexahedral linear reduced integration unit C3D8R.

[0021] In step S2, the bottom displacement boundary condition of the three-dimensional slope finite element model is set as a fixed constraint, the surrounding displacement boundary conditions are set as a vertical constraint, and the upper surface displacement boundary condition is set as a free boundary.

[0022] In step S3, secondary development is performed using the embedded subroutine USDFLD of the finite element analysis software ABAQUS. The material properties are customized in the form of field variables. With the help of the random field method, the spatial morphology of the discontinuous broken medium in the internal space of the rock slope is finely characterized by indirectly adjusting the random field related parameters, thereby constructing a numerical model of the rock slope with poor geology.

[0023] The specific steps of step S3 are:

[0024] 1) Clarify the subroutine USDFLD format and custom code function partition;

[0025] 2) Use the Box-Muller algorithm to generate a three-dimensional random number matrix that obeys the standard normal distribution M ( a , b , c ), as the data frame for subsequent linear interpolation of random numbers in the natural coordinate system, use either of the following two equations to calculate a random number that obeys the standard normal distribution Z :

[0026] (1);

[0027] In formula (1): Z 0 and Z 1 is an independent random variable that conforms to the standard normal distribution; U 1 and U 2 are two independent random numbers that follow a uniform distribution; is the ratio of pi;

[0028] 3) Horizontal inclination of discontinuous fractured media determined by exploration β , rotate the coordinate system of each node of the three-dimensional slope finite element model to obtain the rotated coordinates:

[0029] (2);

[0030] In formula (2): C x , C y , C z are the coordinates in the three coordinate axis directions after rotation; COORD( x ), COORD( y ), COORD( z) are the coordinates before rotation;

[0031] 4) The correlation length in the random field correlation function is used to indirectly characterize the average length of the discontinuous broken medium. Based on the set correlation length values ​​in the three directions of space, the node coordinates of the three-dimensional slope finite element model are scaled and rotated as a whole to determine the relative position of the nodes in space. The scaling formula is:

[0032] (3);

[0033] In formula (3): SF x , SF y , SF z They are the relative positions of the coordinate system after scaling; RL x , RL y , RL z They are the relevant length values ​​in three directions of space;

[0034] 5) The scaled coordinate system is rounded, and the relative position in the natural coordinate system after rounding is expressed as II, JJ, KK. Then, the relative position of the node in the natural coordinate system is compared with the three-dimensional random number matrix using the eight-node hexahedral element shape function. M ( a , b , c ) is converted accordingly to generate random values ​​with spatial correlation and standard normal distribution at each node. RV , the conversion formula is:

[0035] (4);

[0036] In formula (4): f 1, f 2, f 3, f 4, f 5, f 6, f 7, f 8 are the shape functions of the eight-node hexahedral element;

[0037] 6) Select several range sub-intervals consisting of upper and lower bounds on the horizontal coordinate system of the probability density function of the standard normal distribution T i ( m , n ),in i is a subinterval, m and nare the lower and upper bounds of the interval respectively. Each range subinterval is used to determine the medium type where the random value is generated; the average width of each subinterval represents the relative thickness of the discontinuous broken medium, the interval between each subinterval represents the relative density of the discontinuous broken medium, and the total area of ​​each subinterval represents the percentage of the broken medium model area, so as to reflect the spatial morphology of the discontinuous broken medium in the internal space of the rock slope;

[0038] 7) Determine the medium type. If the random value generated at the node of the three-dimensional slope finite element model RV In each defined sub-interval T i ( m , n ), the medium type at the node is broken medium, and the random value generated at the node is replaced by the relative strength value of the broken medium; on the contrary, if the random value generated at the node of the three-dimensional slope finite element model is RV Not in any of the defined subintervals T i ( m , n ), the medium type at the node is intact rock mass, and the random value generated at the node is replaced by the rock mass strength value.

[0039] In step S4, a finite element stability analysis is performed on the established numerical model of the poor geological rock slope. After the ground stress balance analysis step is completed, a static analysis step is performed. In the static analysis step, the strength reduction method is used to reduce the strength of the rock mass and the crushing medium by the same coefficient until the slope becomes generally unstable.

[0040] In step S5, the calculation result file obtained in step S4 is opened in the CAE function module interface of the finite element analysis software, and the custom field variable FV and plastic strain in the subroutine USDFLD are used as output variables. The numerical model of the rock slope containing spatial discontinuous crushing medium and the corresponding slope instability failure mode are respectively displayed. The stability state of the slope under different working conditions is analyzed, its internal instability mechanism is clarified, and the slope stability safety risk assessment is performed.

[0041] When the horizontal inclination angle of the discontinuous broken medium inside the rock layer is less than 90°, it is a traction-type deep landslide; when the horizontal inclination angle is equal to 90°, it is a shallow landslide; when the horizontal inclination angle is greater than 90°, it is a push-type deep landslide.

[0042] The present invention has the following beneficial effects:

[0043] 1. The present invention uses the embedded subroutine of finite element software as a technical means, gives full play to the advantage of the modified linear estimation method in efficiently generating multidimensional random fields, can be organically coupled with millions of finite element unit grids of arbitrary shapes, and at the same time utilizes the powerful kernel computing power of the finite element to quickly generate a three-dimensional rock slope numerical model containing spatial discontinuous broken media, which can finely depict the smooth transition state of the interface between the broken medium and the rock mass, and can generally more realistically characterize the spatial existence form of the discontinuous broken medium, effectively breaking through the limitations of existing methods in terms of model dimension, technical implementation, generation efficiency, etc., and can save a lot of computing resources and time costs.

[0044] 2. The present invention can be combined with the spatial characteristics of the crushed medium in the research area, and on the basis of the constructed rock slope model containing spatial discontinuous crushed medium, the slope stability calculation and analysis can be carried out. According to the different failure modes, the instability mechanism of the slope under different working conditions can be clarified, and then an effective comprehensive prevention and control plan for slope reinforcement can be proposed in a targeted manner, which is conducive to promoting the further development of landslide risk assessment and disaster prevention and mitigation of unfavorable geological rock slopes under complex conditions, and has high engineering practical value.

[0045] 3. The present invention has wide applicability. It is not limited to characterizing discontinuous broken media inside rock slopes. It can also be expanded to simulate complex internal structures of large underground caverns, tunnels, foundations and other projects. Combined with modern automation, information and intelligent technologies such as digital twins, it provides a powerful tool for safety evaluation and comprehensive prevention and control of such projects, and has good economic, social and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0047] Figure 1 It is a flow chart of the present invention.

[0048] Figure 2 Schematic diagram of the geometric dimensions of the model in the three-dimensional rock slope model of an embodiment of the present invention.

[0049] Figure 3 It is a schematic diagram of the definition of the horizontal inclination angle of the crushing medium in the three-dimensional rock slope model according to an embodiment of the present invention.

[0050] Figure 4 The numerical model of the adverse geological rock slope with a horizontal inclination angle of 60° of the crushing medium is represented by the present invention.

[0051] Figure 5 The present invention shows that when the horizontal inclination angle of the crushing medium is 60°, the corresponding slope instability failure mode.

[0052] Figure 6 The present invention represents the numerical model of the unfavorable geological rock slope with a horizontal inclination angle of 90° of the crushing medium.

[0053] Figure 7 The present invention shows the corresponding slope instability failure mode when the horizontal inclination angle of the crushing medium is 90°.

[0054] Figure 8 The present invention represents the numerical model of the unfavorable geological rock slope with a horizontal inclination angle of 120° of the crushing medium.

[0055] Fig. 9 The present invention shows the corresponding slope instability failure mode when the horizontal inclination angle of the crushing medium is 120°.

[0056] Fig.10 It is a schematic diagram of the safety risk assessment and comprehensive prevention and control technical route of the present invention. DETAILED DESCRIPTION

[0057] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] See also Figure 1 The method for reconstructing and evaluating the stability of a three-dimensional discontinuous crushed medium in a rock slope provided by an embodiment of the present invention comprises the following steps:

[0059] S1. Within the scope of the site of the poor geological rock slope, detect the structural composition of the rock layer inside the slope and determine the overall spatial characteristics and mechanical parameters of the discontinuous broken medium inside the rock layer.

[0060] In S1, the electrical sounding geophysical method is used to detect the rock structure inside the slope, and the physical and mechanical properties of the crushed medium are determined with the help of in-situ or indoor geotechnical tests. The overall spatial characteristics and mechanical parameters of the discontinuous crushed medium are determined, and the spatial morphology of the discontinuous crushed medium inside the slope is preliminarily presented by geological sketching.

[0061] The overall spatial characteristics include average length, average thickness, horizontal inclination and relative density; the mechanical parameters include relative strength.

[0062] Specifically, within the plane of the site of the studied unfavorable geological rock slope, the electric depth sounding geophysical method is used to detect the rock structure inside the slope, and with the help of geotechnical tests, the overall spatial characteristics of the discontinuous broken medium, such as average length, average thickness, horizontal inclination, relative density, and physical and mechanical properties, such as relative strength, are determined to provide parameter basis for the subsequent three-dimensional model construction. Based on the obtained data, the spatial form of the discontinuous broken medium inside the slope is preliminarily presented by using geological sketches for comparison with the constructed three-dimensional numerical model of the unfavorable geological rock slope.

[0063] S2. According to the geometric dimensions of the slope area, a three-dimensional slope finite element model is constructed using finite element analysis software.

[0064] In S2, the corresponding three-dimensional slope finite element model is established by using the CAE function module in the finite element analysis software ABAQUS, setting the constitutive model, elastic parameters and displacement boundary conditions as initial conditions, establishing the ground stress equilibrium analysis step and the static analysis step, and using the free meshing technology. The three-dimensional eight-node hexahedral linear reduced integration unit C3D8R is used to divide the unit grid of the three-dimensional slope finite element model.

[0065] The bottom displacement boundary condition of the three-dimensional slope finite element model is set as a fixed constraint, the surrounding displacement boundary conditions are set as vertical constraints, and the upper surface displacement boundary condition is set as a free boundary.

[0066] For details, see Figure 2 , according to an embodiment of the present invention, the geometric dimensions of the slope area are determined, and the corresponding three-dimensional slope finite element model is established by using the CAE function module in the finite element analysis software ABAQUS, and the initial conditions such as the constitutive model, elastic parameters, and displacement boundary conditions are set, wherein the displacement boundary conditions at the bottom of the model are set as fixed constraints, and the surrounding areas are set as vertical constraints, that is, sliding is allowed along the surface, and the upper surface is set as a free boundary. Two calculation and analysis steps are established, namely the first geostress equilibrium analysis step and the second static analysis step. Using free meshing technology, the three-dimensional eight-node hexahedral linear reduced integration unit C3D8R is used to refine the unit mesh of the three-dimensional slope finite element model; the model file is exported as an INP source file, and the relevant statements are modified to associate the model strength parameters with the ABAQUS embedded subroutine USDFLD field variable FV.

[0067] S3. Use the random field method to precisely characterize the discontinuous fractured medium in the internal space of the rock slope and construct a numerical model of the rock slope with poor geology.

[0068] In S3, the embedded subroutine USDFLD of the finite element analysis software ABAQUS is used for secondary development. The program code is written in the custom area of ​​the subroutine. With the help of the random field method, the spatial morphology of the spatially discontinuous broken medium is finely characterized by indirectly adjusting the random field related parameters, thereby constructing a numerical model of the rock slope with poor geological conditions. The present invention uses the modified linear estimation method to generate the random field, thereby providing a powerful tool for the construction of the numerical model of the rock slope with spatially discontinuous broken medium. The specific implementation steps are as follows:

[0069] 1) Clarify the subroutine USDFLD format and custom code functional partitioning. The specific format and functional partitioning of the subroutine are as follows:

[0070] SUBROUTINE USDFLD (FIELD, STATEV, PNEWDT, DIRECT, T, CELENT, TIME,DTIME, CMNAME, ORNAME, NFIELD, NSTATV, NOEL, NPT, LAYER, KSPT, KSTEP, KINC,NDI, NSHR, COORD, JMAC, JMATYP, MATLAYO, LACCFLA)

[0071] INCLUDE 'ABA_PARAM.INC'

[0072] CHARACTER*80 CMNAME, ORNAME

[0073] CHARACTER*3FLGRAY(15)

[0074] DIMENSION FIELD(NFIELD), STATEV(NSTATV), DIRECT(3,3), T(3,3), TIME(2)

[0075] DIMENSION ARRAY(15), JARRAY(15), JMAC(*), JMATYP(*), COORD(*)

[0076] ! (The following is the user code customization area)

[0077] ! 1. Three-dimensional random number matrix generation area

[0078] ! 2. Discontinuous crushing medium spatial morphology parameter setting area

[0079] ! 3. Three-dimensional random field generation area

[0080] ! 4. Definition area of ​​each sub-interval of the horizontal coordinate system of the probability density function of the standard normal distribution

[0081] 5. Media determination area

[0082] RETURN

[0083] END

[0084] 2) Use the Box-Muller algorithm to generate a three-dimensional random number matrix that obeys the standard normal distribution M ( a , b , c ), in the embodiment of the present invention a , b , c The values ​​are all set to 500, which serve as the data framework for subsequent linear interpolation of random numbers in the natural coordinate system. The embodiment of the present invention provides a method for generating a random number in a matrix, using any of the following two equations to calculate a random number that obeys a standard normal distribution: Z :

[0085] (1);

[0086] In formula (1): Z 0 and Z 1 is an independent random variable that conforms to the standard normal distribution; U 1 and U 2 are two independent random numbers that follow a uniform distribution.

[0087] 3) Horizontal inclination of discontinuous fractured media determined by exploration β , see Figure 3 , rotate the coordinate system of each node of the model to Z Axis rotation, the rotation formula is as follows:

[0088] (2);

[0089] In formula (2): C x , C y , C z are the coordinate systems in the three coordinate axis directions after rotation; COORD( x ), COORD( y ), COORD( z ) are the coordinate systems before rotation.

[0090] 4) The correlation length in the random field correlation function is used to indirectly characterize the average length of the discontinuous crushing medium. Based on the set correlation length values ​​in the three directions of space, the coordinates of the model nodes are scaled and rotated as a whole to determine their relative positions in space. The scaling formula is as follows:

[0091] (3);

[0092] In formula (3): SF x , SF y , SF z They are the relative positions of the coordinate system after scaling; RL x , RL y , RL z They are the relevant length values ​​in the three directions of space respectively.

[0093] 5) The scaled coordinate system is rounded, and the relative position in the natural coordinate system after rounding is expressed as II, JJ, KK, and then the eight-node hexahedral unit shape function is used, that is, f 1, f 2, f 3, f 4, f 5, f 6, f 7, f 8. Compare the relative position of the node natural coordinate system with the three-dimensional random number matrix data frame M ( a , b , c ) is converted accordingly, and random values ​​with spatial correlation and standard normal distribution are generated at each finite element node. RV , the conversion formula is as follows:

[0094] (4);

[0095] In formula (4): f 1, f 2, f 3, f 4, f 5, f 6, f 7, f 8 are the shape functions of the eight-node hexahedral element.

[0096] 6) Select several range sub-intervals consisting of upper and lower bounds on the horizontal coordinate system of the probability density function of the standard normal distribution T i (m , n ),in i is the number of subintervals, m and n are the lower and upper bounds of the interval, respectively. Each range sub-interval is used to determine the type of medium where the random value is generated, i.e., broken medium or intact rock mass; wherein, the average width of each sub-interval represents the relative thickness of the discontinuous broken medium, the interval between each sub-interval represents the relative density of the discontinuous broken medium, and the total area of ​​each sub-interval represents the percentage of the broken medium model area, so as to reflect the spatial form of the discontinuous broken medium in the internal space of the rock slope. In the embodiment of the present invention, four left-right symmetrical sub-areas are selected, namely T 1(- m 1, - m 2), T 2(- m 3, - m 4), T 3( m 4, m 3), T 4( m 2, m 1).

[0097] 7) Determine the medium type. If the random value generated at the node of the three-dimensional slope finite element model RV In each defined sub-interval T i ( m , n ), the medium type at the node is a broken medium, and the random value generated at the node is replaced by the relative strength value of the broken medium. In the embodiment of the present invention, the value is set as variable ST1; on the contrary, if the random value generated at the node of the three-dimensional slope finite element model is RV Not in any of the defined subintervals T i ( m , n ), the medium category at the node is intact rock mass, and the random value generated at the node is replaced with the rock mass strength value accordingly. In the embodiment of the present invention, the value is set as variable ST2. The implementation method of determining the medium category is as follows:

[0098] IF (RV .GT. -m1 .and. RV .LT. -m2) THEN

[0099] In ABAQUS software post-processing, FIELD(1) corresponds to the output field variable FV

[0100] FIELD(1)=ST1! Assign the relative strength value of the crushing medium to the variable FIELD

[0101] ELSE IF (RV .GT. -m3 .and. RV .LT. -m4) THEN

[0102] FIELD(1)=ST1

[0103] ELSE IF (RV .GT. m4 .and. RV .LT. m3) THEN

[0104] FIELD(1)=ST1

[0105] ELSE IF (RV .GT. m2 .and. RV .LT. m1) THEN

[0106] FIELD(1)=ST1

[0107] ELSE

[0108] If RV is not within the above definition, the rock mass strength value is assigned to the variable FIELD

[0109] FIELD(1)=ST2

[0110] ENDIF

[0111] S4. Use the strength reduction method to perform stability analysis and calculation on the constructed numerical model of the poor geological rock slope.

[0112] In S4, the established numerical model of the bad geological rock slope is subjected to finite element stability analysis and calculation, and after the ground stress balance analysis step is completed, the static analysis step is performed. In the static analysis step, the strength reduction method is used to reduce the strength of the rock mass and the crushing medium by the same coefficient until the slope becomes generally unstable. The reduction coefficient at this time is usually approximately the slope stability safety factor. In the embodiment of the present invention, the sudden change of the displacement of the slope vertex is used as the instability judgment condition.

[0113] S5. Through the calculation results, the numerical model of the unfavorable geological rock slope containing spatially discontinuous broken media and the corresponding slope instability failure mode are demonstrated, and the stability of the unfavorable geological rock slope is evaluated.

[0114] In S5, the calculation result file is opened in the software CAE interface, and the subroutine custom field variable FV and plastic strain are used as output variables to display the numerical model of the rock slope containing spatial discontinuous crushing medium and the corresponding slope instability failure mode, respectively. Figures 4 to 9 . Analyze the slope stability under different working conditions, clarify its internal instability mechanism, and conduct slope stability safety risk assessment, such as Fig.10 shown.

[0115] See also Figures 4 to 9 When the horizontal inclination angle of the discontinuous broken medium inside the rock layer is less than 90°, it is a traction-type deep landslide; when the horizontal inclination angle is close to 90°, it is a shallow landslide; when the horizontal inclination angle is greater than 90°, it is a push-type deep landslide.

[0116] Specifically, from Figure 4 , 6 As can be seen from Figures 8 and 8, the technical method proposed by the present invention can effectively characterize the spatial discontinuous crushing medium in the three-dimensional rock slope with poor geology, can finely depict the smooth transition state of the interface between the crushing medium and the rock mass, and can generally more realistically reflect the possible existence form of the discontinuous crushing medium in space. This example further illustrates the uniqueness and effectiveness of the technical method proposed by the present invention in efficiently characterizing the discontinuous crushing medium inside the three-dimensional rock slope.

[0117] from Figure 5 , 7 As can be seen from Figure 9, the horizontal inclination of the crushing medium has an important influence on the failure mode of slope instability. When it is less than 90°, it mainly manifests as a traction-type deep landslide; when it is equal to 90°, it mainly manifests as a shallow landslide; when it is greater than 90°, it mainly manifests as a push-type deep landslide. The three show obvious differences in the mechanism of slope instability, which is closely related to the relative direction of the crushing medium inclination and the slope body.

[0118] When the crushing medium is closer to the slope angle, the instability sliding zone of the overlying rock mass is more likely to move along the existing crushing zone inside the slope, forming a greater thrust on the slope foot, thereby accelerating the movement of the landslide. At this time, the destructiveness caused by the landslide is often greater. Correspondingly, the traction-type deep landslide will pull the overlying rock mass to slide, and the landslide disaster caused is often larger. At the same time, the shallow landslide disaster that occurs when the crushing medium is close to the vertical state is also worthy of attention.

[0119] To this end, it is necessary to propose effective comprehensive prevention and control plans for slope reinforcement based on the identified landslide risk level, such as adding anchor rods perpendicular to the direction of the broken zone; consolidation grouting in specific areas to increase the overall strength of the broken medium. In addition, modern technical means such as digital twins and integrated sky-ground monitoring can be combined to establish an automated monitoring and intelligent early warning platform for landslide disasters on unfavorable geological rock slopes in the project impact area, gradually improve the disaster prevention and mitigation system for such landslide disasters, and effectively protect the lives and property of personnel at the project site. With regard to this process, the technical implementation route proposed in the present invention is as follows: Fig.10As shown in the figure, after the initial analysis of the slope instability mechanism based on the calculation results, the potential sliding surface of the bad geological rock slope is first determined, focusing on the broken medium penetration area, then identifying the landslide risk factors, determining the risk level, and preliminarily estimating the landslide disaster losses. Then, deformation monitoring is strengthened through InSAR, drones, GNSS, multi-point displacement meters and other technologies. Finally, an automated monitoring and intelligent early warning platform for landslide disasters on bad geological rock slopes is established to minimize the losses caused by landslide disasters. In the above process, the actual situation of the project site is dynamically fed back to optimize and adjust the comprehensive prevention and control plan for rock slopes.

[0120] This invention effectively breaks through the limitations of existing methods in terms of model dimension, technical implementation, generation efficiency, etc. on such problems. It has high engineering practical value and good universality. It can be combined with modern technical means such as digital twins and integrated sky-ground monitoring to help promote further development in risk assessment and disaster prevention and mitigation of landslide disasters in adverse geological rock slopes under complex conditions.

[0121] The above embodiments are only used to illustrate the present invention, wherein the structure, connection mode and manufacturing process of each component may be changed. Any equivalent transformations and improvements based on the technical solution of the present invention should not be excluded from the protection scope of the present invention.

Claims

1. A three-dimensional discontinuous fractured medium reconstruction and stability assessment method for rock slopes, characterized in that: The following steps are involved: S1. Within the scope of the site of the bad geological rock slope, detect the rock structure composition inside the slope and determine the overall spatial characteristics and mechanical parameters of the discontinuous broken medium inside the slope; S2. According to the geometric dimensions of the slope area, a three-dimensional slope finite element model is constructed using finite element analysis software; S3. Use the embedded subroutine USDFLD of the finite element analysis software ABAQUS for secondary development, customize material properties in the form of field variables, and use the random field method to indirectly adjust the random field related parameters to finely characterize the spatial morphology of the discontinuous broken medium in the rock slope, and then construct a numerical model of the unfavorable geological rock slope. The specific steps are as follows: S3-1. Clarify the subroutine USDFLD format and custom code function partition; S3-2, using the Box-Muller algorithm to generate a three-dimensional random number matrix that obeys the standard normal distribution; S3-3, according to the horizontal inclination of the discontinuous broken medium determined by the exploration, the coordinate system of each node of the three-dimensional slope finite element model is rotated to obtain the rotated coordinates; S3-4, using the correlation length in the random field correlation function to indirectly characterize the average length of the discontinuous broken medium, based on the set correlation length values ​​in three directions of space, the node coordinates of the three-dimensional slope finite element model are scaled and rotated as a whole to determine the relative positions of the nodes in space; S3-5. Use the shape function of the eight-node hexahedral unit to convert the relative position of the node in the natural coordinate system into a three-dimensional random number matrix, and generate random values ​​with spatial correlation and standard normal distribution at each node. RV ; S3-6. Select several range sub-intervals consisting of upper and lower bounds on the horizontal coordinate system of the probability density function of the standard normal distribution. T i ( m , n ),in i is the number of subintervals, m and n are the lower and upper bounds of the interval respectively; S3-7, determine the medium type; if the random value generated at the node of the three-dimensional slope finite element model RV In each defined sub-interval T i ( m , n ), then the medium type at this node is broken medium; If the random values ​​generated at the nodes of the three-dimensional slope finite element model RV Not in any of the defined subintervals T i ( m , n ), then the medium type at this node is intact rock mass, which can precisely characterize the spatial morphology of the discontinuous broken medium in the rock slope; S4. Use the strength reduction method to perform stability analysis and calculation on the constructed numerical model of the bad geological rock slope; S5. Through the calculation results, the numerical model of the unfavorable geological rock slope containing spatially discontinuous broken media and the corresponding slope instability failure mode are demonstrated, and the stability of the unfavorable geological rock slope is evaluated.

2. The method for three-dimensional discontinuous crushing medium reconstruction and stability assessment of rock slope according to claim 1 is characterized in that: In step S1, the rock structure inside the slope is detected by electrical sounding geophysical method, the physical and mechanical properties of the crushing medium are determined by in-situ or indoor geotechnical test methods, the overall spatial characteristics and mechanical parameters of the discontinuous crushing medium are determined, and the spatial morphology of the discontinuous crushing medium inside the slope is obtained by geological sketching.

3. The method for three-dimensional discontinuous crushing medium reconstruction and stability assessment of rock slope according to claim 2 is characterized in that: In step S1, the overall spatial characteristics include average length, average thickness, horizontal inclination and relative density; and the mechanical parameters include relative strength.

4. The method for three-dimensional discontinuous crushing medium reconstruction and stability assessment of rock slope according to claim 1 is characterized in that: In step S2, a three-dimensional slope finite element model is established by using the CAE function module in the finite element analysis software ABAQUS, setting the constitutive model, elastic parameters and displacement boundary conditions, establishing a ground stress equilibrium analysis step and a static analysis step, and using the free meshing technology to divide the three-dimensional slope finite element model unit grid using a three-dimensional eight-node hexahedral linear reduced integration unit C3D8R.

5. The method for three-dimensional discontinuous crushing medium reconstruction and stability assessment of rock slope according to claim 4 is characterized in that: In step S2, the bottom displacement boundary condition of the three-dimensional slope finite element model is set as a fixed constraint, the surrounding displacement boundary conditions are set as a vertical constraint, and the upper surface displacement boundary condition is set as a free boundary.

6. The method for three-dimensional discontinuous crushed medium reconstruction and stability assessment of rock slope according to claim 1, characterized in that: In S3-2, the Box-Muller algorithm is used to generate a three-dimensional random number matrix that obeys the standard normal distribution. M ( a , b , c ), as the data frame for subsequent linear interpolation of random numbers in the natural coordinate system, use either of the following two equations to calculate a random number that obeys the standard normal distribution Z : （1）； In formula (1): Z 0 and Z 1 is an independent random variable that conforms to the standard normal distribution; U 1 and U 2 are two independent random numbers that follow a uniform distribution; is pi; In S3-3, the horizontal inclination of the discontinuous fractured medium determined by exploration is β , rotate the coordinate system of each node of the three-dimensional slope finite element model to obtain the rotated coordinates: （2）； In formula (2): C x , C y , C z are the coordinates in the three coordinate axis directions after rotation; COORD( x ), COORD( y ),COORD( z ) are the coordinates before rotation; In S3-4, the correlation length in the random field correlation function is used to indirectly characterize the average length of the discontinuous broken medium. Based on the set correlation length values ​​in the three directions of space, the node coordinates of the three-dimensional slope finite element model are scaled and rotated as a whole to determine the relative position of the nodes in space. The scaling formula is: ；（3）； In formula (3): SF x , SF y , SF z They are the relative positions of the coordinate system after scaling; RL x , RL y , RL z They are the relevant length values ​​in three directions of space; In S3-5, the scaled coordinate system is rounded, and the relative position in the natural coordinate system after rounding is expressed as II, JJ, and KK. Then, the relative position of the node in the natural coordinate system is compared with the three-dimensional random number matrix using the eight-node hexahedral element shape function. M ( a , b , c ) is converted accordingly to generate random values ​​with spatial correlation and standard normal distribution at each node. RV , the conversion formula is: （4）； In formula (4): f 1, f 2, f 3, f 4, f 5, f 6, f 7, f 8 are the shape functions of the eight-node hexahedral element; In S3-6, select several range subintervals consisting of upper and lower bounds on the horizontal coordinate system of the probability density function of the standard normal distribution T i ( m , n ),in i is a subinterval, m and n are the lower and upper bounds of the interval respectively. Each range subinterval is used to determine the medium category where the random value is generated. The average width of each subinterval represents the relative thickness of the discontinuous broken medium, the interval between each subinterval represents the relative density of the discontinuous broken medium, and the total area of ​​each subinterval represents the percentage of the broken medium model area, so as to reflect the spatial morphology of the discontinuous broken medium in the internal space of the rock slope. In S3-7, the medium type is determined. If the random value generated at the node of the three-dimensional slope finite element model RV In each defined sub-interval T i ( m , n ), the medium type at the node is broken medium, and the random value generated at the node is replaced by the relative strength value of the broken medium; on the contrary, if the random value generated at the node of the three-dimensional slope finite element model is RV Not in any of the defined subintervals T i ( m , n ), the medium type at the node is intact rock mass, and the random value generated at the node is replaced by the rock mass strength value.

7. The method for three-dimensional discontinuous crushing medium reconstruction and stability assessment of rock slope according to claim 1, characterized in that: In step S4, a finite element stability analysis is performed on the established numerical model of the poor geological rock slope. After the ground stress balance analysis step is completed, a static analysis step is performed. In the static analysis step, the strength reduction method is used to reduce the strength of the rock mass and the crushing medium by the same coefficient until the slope becomes generally unstable.

8. The method for three-dimensional discontinuous crushing medium reconstruction and stability assessment of rock slope according to claim 7, characterized in that: In step S5, the calculation result file obtained in step S4 is opened in the CAE function module interface of the finite element analysis software, and the custom field variable FV and plastic strain in the subroutine USDFLD are used as output variables. The numerical model of the rock slope containing spatial discontinuous crushing medium and the corresponding slope instability failure mode are respectively displayed. The stability state of the slope under different working conditions is analyzed, its internal instability mechanism is clarified, and the slope stability safety risk assessment is performed.

9. The method for three-dimensional discontinuous crushing medium reconstruction and stability assessment of rock slope according to claim 8, characterized in that: When the horizontal inclination angle of the discontinuous broken medium inside the rock layer is less than 90°, it is a traction-type deep landslide; when the horizontal inclination angle is equal to 90°, it is a shallow landslide; when the horizontal inclination angle is greater than 90°, it is a push-type deep landslide.

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