A block stability analysis method and system under the framework of continuous medium numerical analysis

Abstract

The present invention relates to the technical field of surrounding rock stability of underground caverns and slope engineering, and discloses a block stability analysis method and system under the framework of continuous medium numerical analysis, including: establishing a numerical analysis model including the boundary morphology of the block structure surface to be analyzed; performing continuous grid separation on the block boundary and constraining the separated grid; applying initial constraints and initial stress to the block after grid separation; obtaining the initial stable state of the block by calculation; gradually reducing the strength parameters of the block structure surface in equal proportion, and adjusting the strength parameters corresponding to the structural surface rod unit to obtain the block safety factor; when the safety factor requirements specified in the specification are not met, stabilizing the block through support measures, and analyzing the block safety factor after the support force is applied. The limitations of traditional methods are overcome, and the simulation accuracy of the numerical model to the actual situation is improved. It is possible to judge the current stable state of the block and evaluate its safety under different support measures.

Description

Technical Field

[0001] The invention relates to the technical field of surrounding rock stability of underground caverns and slope engineering, and in particular to a block stability analysis method and system under a continuous medium numerical analysis framework. Background Art

[0002] Rock mass is an obviously heterogeneous material, and one of the most obvious manifestations of its heterogeneity is the various structural surfaces inside it. After the excavation of underground caverns and slopes, the structural surfaces in the rock mass and the excavation free surfaces may be combined to form independent blocks. These independent blocks have the risk of instability after the excavation surfaces of underground caverns and slopes are formed, which poses a great challenge to the stability of the surrounding rock of the project. Large blocks even pose a threat to personnel safety. Therefore, in the design and construction process of large underground caverns and slopes, block stability analysis is an indispensable content and one of the key issues concerning the stability of the surrounding rock of underground caverns and slopes. After block stability analysis, sufficient support can be provided for block support design to ensure the safety of underground caverns and slope projects.

[0003] At present, block stability analysis methods are mainly based on theoretical methods such as block theory, or non-continuous medium mechanics methods such as discrete elements. Although traditional continuous medium numerical analysis methods such as finite element and finite difference methods are the most widely used in factories, they are rarely used to carry out block stability analysis due to the constraints of their own continuity assumptions. This patent proposes a method for carrying out block stability analysis under the framework of continuous medium numerical analysis, enriching the technical means of block stability analysis. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is: to overcome the limitation that the traditional block stability analysis needs to rely on theoretical methods and discontinuous analysis methods, and to enrich the technical means of block stability analysis.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a block stability analysis method under a continuous medium numerical analysis framework, comprising:

[0007] Establish a numerical analysis model that includes the boundary morphology of the block structure surface being analyzed;

[0008] Continuously separate the block boundaries and constrain the separated grids;

[0009] Apply initial constraints and initial stress to the blocks after mesh separation;

[0010] Through calculation, the initial stable state of the block is obtained;

[0011] The strength parameters of the block structure surface are gradually reduced in equal proportion, and the strength parameters corresponding to the structural surface bar elements are adjusted to obtain the block safety factor;

[0012] When the safety factor requirements specified in the code are not met, support measures are taken to stabilize the block, and the safety factor of the block after the support force is applied is analyzed.

[0013] As a preferred solution of the block stability analysis method under the continuous medium numerical analysis framework of the present invention, wherein: the numerical analysis model includes the structural surface boundaries constituting the block, and at least two structural surfaces constitute the block;

[0014] The free surface of the block;

[0015] The outer side of the block is close to the surrounding rock, and the surrounding rock range is at least 3 times the range of the block;

[0016] The block information to be analyzed is obtained, and a three-dimensional numerical analysis model of the block is established through commercial modeling software; under the framework of continuous medium numerical analysis, the three-dimensional numerical analysis model of the block is a continuous grid, and a three-dimensional continuity numerical model is obtained.

[0017] As a preferred scheme of the block stability analysis method under the continuous medium numerical analysis framework described in the present invention, wherein: the continuous grid separation includes decomposing each node distributed on the block boundary into two nodes; after the continuous grid nodes are decomposed at the block boundary, the model exhibits discontinuous characteristics at the block boundary, so that there is no interaction on both sides of the block structure surface.

[0018] As a preferred solution of the block stability analysis method under the continuous medium numerical analysis framework of the present invention, wherein: the constraining the separated grid includes introducing a rod unit with dual constraints of tension, compression and shear at the boundary of the block structure surface to re-constrain the boundary of the structure surface;

[0019] The bar unit can be distributed at the centroid of the mesh on both sides of each block structure surface. The bar length is the shortest length that can pass through the mesh on both sides of the structure surface. The equivalent control area of ​​each bar unit is the mesh area of ​​the surface it passes through. The tensile strength parameter and shear strength parameter of the bar unit are the structural surface strength parameter multiplied by the equivalent control area of ​​the bar unit.

[0020] Normal mechanical properties of bar element:

[0021] ,

[0022] in, It represents the normal stiffness of the member unit, and its value range is 10~1000 times of the deformation modulus of the surrounding rock; represents the equivalent control area of ​​the bar element; Represents the unit normal deformation of the member, positive represents expansion deformation, and negative represents compression deformation; represents the normal force of the bar element, It represents the maximum normal force that can be achieved by the bar element;

[0023] Tangential mechanical properties of bar elements:

[0024] ,

[0025] in, It represents the tangential stiffness of the member unit, and its value range is 10~1000 times of the deformation modulus of the surrounding rock; represents the unit tangential deformation of the member, represents the tangential force of the bar element, and It represents the maximum tangential force that the bar element can achieve in two tangential directions;

[0026] The tensile strength and shear strength of the bar element are:

[0027] ,

[0028] ,

[0029] in, represents the tensile strength of the block structure surface, represents the cohesion of the block structure surface, Represents the friction angle of the block structure surface.

[0030] As a preferred solution of the block stability analysis method under the continuous medium numerical analysis framework of the present invention, the initial constraint application includes limiting the node displacement at the model boundary so that it remains unchanged during the calculation and analysis process; no constraint is imposed on the free surface of the block, and boundary normal constraints are imposed on other boundaries;

[0031] The initial stress application includes assigning an initial value to the stress state of each unit of the calculation model based on the original rock stress state of the block, and calculating to a convergent state;

[0032] Excavate the cavern area and obtain the stress state after redistribution after cavern excavation, which is used as the initial stress state for block analysis;

[0033] The initial value assignment includes assigning a preset value to the strength parameter of the rod element during the calculation process to ensure that the rod element is in an elastic working state during the initial stress application process.

[0034] As a preferred solution of the block stability analysis method under the continuous medium numerical analysis framework of the present invention, wherein: the obtaining of the initial stable state of the block includes converting the strength parameters of the rod unit into actual strength parameters, performing finite element numerical simulation analysis on the numerical analysis model, and calculating two situations:

[0035] The first one is to calculate the final convergence and determine that the block is currently in a stable state;

[0036] The second is that the calculation does not converge in the end and it is determined that the block is currently unstable.

[0037] As a preferred solution of the block stability analysis method under the continuous medium numerical analysis framework described in the present invention, the block safety factor includes gradually reducing the strength parameters of the block structure surface in equal proportion and adjusting the strength parameters corresponding to the structure surface bar unit. The strength reduction is expressed as:

[0038] ,

[0039] ,

[0040] ,

[0041] in, represents the strength reduction factor; represents the cohesion of the block structure surface, represents the tensile strength of the block structure surface, represents the friction angle of the block structure surface; correspondingly, , , Respectively represent the cohesion of the block structure surface after strength reduction, the tensile strength of the block structure surface, and the friction angle of the block structure surface; for the initial stable block, It can be gradually increased from 1.0 until the calculation does not converge; for the initially unstable block, It can be gradually reduced from 1.0 until the calculation begins to converge;

[0042] The block safety factor is the critical state of block instability obtained after strength reduction. value;

[0043] The critical state of block instability is determined by the relationship curve between the displacement of the block characteristic point and the strength reduction coefficient. The critical point is characterized by a sudden increase in the slope of the curve, a sharp increase in deformation, and non-convergence of the calculation.

[0044] The safety factor of the block obtained, if it does not meet the safety factor requirements, then apply for support measures to stabilize the block;

[0045] The support force is implemented on the free surface of the block in the form of surface force, and the safety factor of the block after the support force is applied is re-analyzed until the support force makes the block safety factor meet the requirements of the specification.

[0046] A block stability analysis system in a continuous medium numerical analysis framework using any method described in the present invention, wherein:

[0047] Modeling unit, establishing a numerical analysis model including the boundary morphology of the block structure surface to be analyzed; performing continuous grid separation on the block boundary and constraining the separated grid;

[0048] Run the unit to apply initial constraints and initial stress to the blocks after mesh separation;

[0049] The calculation unit obtains the initial stable state of the block through calculation; the strength parameters of the block structure surface are gradually reduced in proportion, and the strength parameters corresponding to the structure surface rod unit are adjusted to obtain the block safety factor; when the safety factor requirements specified in the code are not met, the block is stabilized through support measures, and the block safety factor after the support force is applied is analyzed.

[0050] A computer device comprises: a memory and a processor; the memory stores a computer program, wherein: the processor implements the steps of any one of the methods of the present invention when executing the computer program.

[0051] A computer-readable storage medium stores a computer program, wherein: when the computer program is executed by a processor, the steps of any one of the methods of the present invention are implemented.

[0052] Beneficial effects of the present invention: The block stability analysis method under the framework of continuous medium numerical analysis provided by the present invention overcomes the limitations of traditional methods and enriches the technical means of block stability analysis. By introducing rod units with dual constraints of tension, compression and shear at the boundaries of the block structural surfaces, continuous grid separation and re-constraint are achieved, so that the block boundaries appear as non-continuous features. At the same time, appropriate mechanical parameters are introduced at the boundaries of the structural surfaces to improve the simulation accuracy of the numerical model for actual conditions. The safety factor of the block is determined by gradually reducing the strength parameters of the block structural surface, and support force can be applied when necessary to improve the safety factor of the block to ensure that it meets the requirements of the specifications. This method can not only determine the current stability of the block, but also scientifically evaluate its safety under different support measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0054] Figure 1 An overall flow chart of a block stability analysis method under a continuous medium numerical analysis framework provided by the first embodiment of the present invention;

[0055] Figure 2 A mechanical characteristic diagram of a rod element in a block stability analysis method under a continuous medium numerical analysis framework provided by the first embodiment of the present invention, wherein (a) represents normal mechanical characteristics and (b) represents tangential mechanical characteristics;

[0056] Figure 3 A block structure surface information diagram of a block stability analysis method under a continuous medium numerical analysis framework provided by a second embodiment of the present invention;

[0057] Figure 4 An overall diagram of a numerical analysis model of a block stability analysis method under a continuous medium numerical analysis framework provided by a second embodiment of the present invention;

[0058] Figure 5 The block shape of a numerical analysis model of a block stability analysis method under a continuous medium numerical analysis framework provided by the second embodiment of the present invention;

[0059] Figure 6 A schematic diagram of grid separation of a block stability analysis method in a continuous medium numerical analysis framework provided by a second embodiment of the present invention;

[0060] Figure 7 A schematic diagram of separate grid re-constraint of a block stability analysis method in a continuous medium numerical analysis framework provided by a second embodiment of the present invention;

[0061] Figure 8 A partially enlarged schematic diagram of a separated grid re-constraint of a block stability analysis method in a continuous medium numerical analysis framework provided by a second embodiment of the present invention;

[0062] Fig. 9 A schematic diagram of initial constraint application of a block stability analysis method in a continuous medium numerical analysis framework provided by a second embodiment of the present invention;

[0063] Fig.10 An initial stress state diagram (unit: Pa) of a block stability analysis method under a continuous medium numerical analysis framework provided by the second embodiment of the present invention;

[0064] Fig.11 A post-support strength reduction process curve of a block stability analysis method under a continuous medium numerical analysis framework is provided in accordance with the second embodiment of the present invention. DETAILED DESCRIPTION

[0065] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0066] Example 1, reference Figure 1 , Figure 2 , which is an embodiment of the present invention, provides a block stability analysis method under a continuous medium numerical analysis framework, comprising:

[0067] S1: Numerical analysis model establishment.

[0068] A three-dimensional numerical analysis model of the block is established. In the framework of continuous medium numerical analysis, this numerical analysis model should be a continuous grid. The numerical analysis model includes the boundaries of the structural surfaces that constitute the block. Generally, at least two structural surfaces are required to constitute a block; it includes the free surface of the block; it includes the surrounding rock outside the block, and the surrounding rock range is at least 3 to 5 times the range outside the block.

[0069] It should be noted that the establishment of numerical analysis models is achieved using commercial modeling software, such as Ansys, Hypermesh, Rhino+Griddle, etc.

[0070] S2: Continuous grid separation.

[0071] Each node distributed on the block boundary is decomposed into two nodes. After the continuous mesh nodes are decomposed at the block boundary, the model at this time shows discontinuous characteristics at the block boundary, that is, there is no interaction on both sides of the block structure surface.

[0072] Specifically, the grids on both sides of the block boundary in the continuous grid share nodes on the block boundary, and the nodes under the same coordinate have only one number. The node decomposition here first decomposes the node from 1 number into 2 numbers. The coordinates of the two numbered nodes after decomposition are the same, and the two numbered nodes belong to the grids on both sides of the block respectively. In this way, the grids on both sides of the block are equivalent to not sharing nodes, and the two sides of the block are in a completely discontinuous state.

[0073] S3: Separate the grid and re-constrain it. Introduce rod elements with dual constraints of tension, compression and shear at the boundary of the block structure surface to re-constrain the boundary of the structure surface. The rod elements can be distributed at the centroids of the meshes on both sides of each block structure surface, and the length of the rod is based on just passing through the meshes on both sides of the structure surface. Since the rod element just passes through the centroids of the meshes on both sides of the structure surface, the equivalent control area of ​​each rod element is the mesh area of ​​the surface it passes through; the tensile strength parameter and shear strength parameter of the rod unit are the structural surface strength parameters multiplied by the equivalent control area of ​​the rod element. The mechanical properties of the rod element are as follows: Figure 2 shown.

[0074] Normal mechanical properties of bar element:

[0075] ,

[0076] in, is the normal stiffness of the member unit, and its value can be 10 to 1000 times the deformation modulus of the surrounding rock; is the equivalent control area of ​​the bar element; is the unit normal deformation of the member, positive indicates opening deformation, negative indicates compression deformation; represents the normal force of the bar element, It represents the maximum normal force that can be achieved by the bar element.

[0077] Tangential mechanical properties of bar elements:

[0078] ,

[0079] in, is the tangential stiffness of the member unit, and its value can be 10 to 1000 times the deformation modulus of the surrounding rock; is the unit tangential deformation of the member, represents the tangential force of the bar element, and It represents the maximum tangential force that the bar element can achieve in two tangential directions.

[0080] The tensile strength and shear strength of the bar element are:

[0081] ,

[0082] ,

[0083] in, is the tensile strength of the block structure surface, is the cohesion of the block structure surface, is the friction angle of the block structural surface; for block analysis problems, these parameters can be obtained from geological survey data.

[0084] S4: Initial constraint imposition.

[0085] There are no constraints on the free surfaces of the block, but boundary normal constraints are imposed on other boundaries.

[0086] What needs to be said is that the constraint is to limit the node displacement at the boundary of the model so that it remains unchanged during the calculation and analysis process. The normal constraint is to limit the normal displacement of the node at the boundary of the model.

[0087] S5: Initial stress application.

[0088] Based on the original rock stress state of the block, the stress state of each unit in the calculation model is assigned an initial value and calculated to a convergent state; then, the cavern area is excavated to obtain the stress state after redistribution after cavern excavation, which is used as the initial stress state for block analysis. During the calculation process, the strength parameter of the bar unit can be assigned a maximum value to ensure that the bar unit is in an elastic working state during the initial stress application process.

[0089] S6: Obtain the initial stable state of the block.

[0090] On the basis of the above, the strength parameters of the bar element (including the tensile strength and shear strength in the above formula) are converted into actual strength parameters (referring to and ), and carry out calculation analysis. There are two situations for the final calculation results. The first is that the calculation finally converges, indicating that the block is currently in a stable state; the second is that the calculation does not converge, indicating that the block is currently unstable.

[0091] Furthermore, computational analysis refers to finite element numerical simulation analysis, which is generally carried out using finite element software (it can also be said to be numerical simulation analysis).

[0092] S7: Block safety factor analysis.

[0093] On the basis of S6, the strength parameters of the block structural surface are gradually reduced in equal proportion, and the strength parameters corresponding to the structural surface member units are adjusted. The strength reduction can be expressed by the following formula.

[0094] ,

[0095] ,

[0096] ,

[0097] in, is the strength reduction factor. represents the cohesion of the block structure surface, represents the tensile strength of the block structure surface, represents the friction angle of the block structure surface; correspondingly, , , Respectively represent the block structure surface cohesion, block structure surface tensile strength, and block structure surface friction angle after strength reduction. For the initial stable block, It can be gradually increased from 1.0 until the calculation does not converge. For the initially unstable block, It can be gradually reduced from 1.0 until the calculation begins to converge.

[0098] The block safety factor is the critical state of block instability obtained by strength reduction. The critical state of block instability can be determined by the relationship curve between the displacement of the block characteristic point and the strength reduction coefficient. The critical point is generally characterized by a sudden increase in the slope of the curve, a sharp increase in deformation, and non-convergence of calculation.

[0099] S8: Determination of block safety factor after support.

[0100] If the block safety factor obtained by S7 does not meet the safety factor requirements specified in the code, support measures need to be provided to stabilize the block. The support force can be applied to the free surface of the block in the form of surface force, and then the block safety factor after the support force is applied can be further analyzed using the method shown in S7 until the support force makes the block safety factor meet the code requirements.

[0101] On the other hand, this embodiment also provides a block stability analysis system under a continuous medium numerical analysis framework, which includes:

[0102] The modeling unit establishes a numerical analysis model including the boundary morphology of the block structure surface being analyzed; the block boundary is continuously meshed and the separated mesh is constrained.

[0103] Run the unit to apply initial constraints and initial stress to the blocks after mesh separation.

[0104] The calculation unit obtains the initial stable state of the block through calculation; the strength parameters of the block structure surface are gradually reduced in proportion, and the strength parameters corresponding to the structure surface rod unit are adjusted to obtain the block safety factor; when the safety factor requirements specified in the code are not met, the block is stabilized through support measures, and the block safety factor after the support force is applied is analyzed.

[0105] If the above functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program code.

[0106] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0107] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0108] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0109] Example 2

[0110] Reference Figure 3-Figure 11 , which is an embodiment of the present invention, provides a block stability analysis method under the framework of continuous medium numerical analysis. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0111] The following describes an embodiment of the present invention by taking an underground powerhouse block of a hydropower station as an example.

[0112] S1: Establish a three-dimensional continuous numerical model that includes the boundary morphology of the block structure surface under analysis.

[0113] The structural surface cataloging information of the downstream side wall of a power station main building during the construction period shows that there is a block. The block is composed of three structural surfaces and the main building excavation free surface. The three structural surfaces are: fissure J1, EW / S∠55°~75°; fissure J5-1, N60~90°E / SE∠10~30°; fault fCF-2, N45°~55°E / SE∠85°, such as Figure 3 shown.

[0114] Firstly, a three-dimensional continuous numerical model for the stability analysis of the block was established. Figure 4 The model includes the excavation cavern shape and the block structure surface boundary shape, such as Figure 5 As shown; and the outer side of the block is close to the surrounding rock, and the surrounding rock range is more than 3 times the size of the block and the cavern.

[0115] S2: For the continuous mesh model of block stability analysis, separation treatment is performed at the structural surface boundary.

[0116] For the block stability analysis example shown, the block and the surrounding rock are separated from the original common node connection state of the continuous grid to the non-common node separation state of the discontinuous grid, as shown in Figure 6 At this time, the block of the embodiment of the present invention is completely disconnected from the surrounding rock.

[0117] S3: For the separated block stability analysis separated grid model, the bar elements are used for re-constraint at the structural surface boundary.

[0118] For the block stability analysis example shown, the block, surrounding rock and cavern are all divided by tetrahedral meshes, that is, the structural surface between the block and the surrounding rock is discretized into triangular surface meshes. Although, after the implementation of S2, the block and the surrounding rock are separated at the boundary of the structural surface, that is, one triangular surface mesh is separated into two; but the node positions and centroid positions of the triangular surface mesh on the block side and the triangular surface mesh on the surrounding rock side are the same. Figure 7 and Figure 8 According to S3, a rod element is inserted at the block structure surface. The rod element is based on just passing through the triangular surface mesh. The rod element can be inserted at the centroid of each triangular surface mesh.

[0119] According to the geological data of the power station, the deformation modulus of the rock mass in the underground powerhouse area is 22.5GPa, Poisson's ratio is 0.2, and the density is 2650kg / m3. The cohesion c of the fault fCF-2 is 0.1MPa and the friction angle is is 26.56°, the cohesion c of cracks J1 and J5-1 is 0.15MPa, and the friction angle The angle is 35°. Using the mechanical properties of the S3 bar element, the normal stiffness of the bar element is set. and tangential stiffness are 100 times the deformation modulus of the rock mass, i.e. 2250 GPa; the cohesion c of the rod element on J1 and J5-1 is set to 0.15 MPa, and the friction angle is 35°, the cohesion c of the upper bar element of fCF-2 is set to 0.1 MPa, and the friction angle is 26.56°; when analyzing the block, follow the code and set the tensile strength of the bar unit at each part of J1, J5-1, and fCF-2 All are set to 0, that is, the effect of tensile strength of structural surface is not considered. In addition, elastic material is used for rock mass area, and material parameters are assigned according to rock mass deformation modulus 22.5GPa, Poisson's ratio 0.2, and density 2650kg / m3.

[0120] S4: Initial constraint application. No constraints are imposed on the free surface of the block, and boundary normal constraints are imposed on other boundaries.

[0121] For this embodiment, S3 has assigned material parameters to each part of the block stability analysis model. Before starting the simulation, the model boundary conditions need to be determined. Since the model boundary is larger than the cave and block size by more than 3 times, it has exceeded the influence range of the block. Normal fixed constraints can be applied to the side boundaries and bottom boundaries of the model, such as Fig. 9 shown.

[0122] S5: Initial stress state application. Based on the original rock stress state of the block, the stress state of each unit in the calculation model is assigned an initial value and calculated to a convergent state; then, the cavern area is excavated to obtain the stress state after redistribution after the cavern excavation. During the calculation process, the strength parameter of the rod unit can be assigned a maximum value to ensure that the rod unit is in an elastic working state during the initial stress application process.

[0123] In S4, normal constraints are applied to the side and bottom boundaries of the computational model. For the top boundary of the computational model, a normal load can be applied according to the magnitude of the self-weight stress in the cavern area. Specifically, according to engineering geological data, the self-weight stress in the cavern area of ​​this embodiment is about 18MPa; and the actual model is not established to the actual surface elevation within the elevation range, and it is difficult to automatically generate the self-weight stress field through the self-weight of the material. Therefore, a uniformly distributed pressure load of 18MPa is applied to the upper surface of the model to represent the self-weight pressure of the rock mass outside the model range. Then, the strength parameters of each rod unit are assigned a maximum value, that is, the cohesion c of the rod unit at each part of J1, J5-1, and fCF-2 is set to 100GPa, and the friction angle is set to 100GPa. Set to 89.9°, tensile strength Set to 100GPa; on this basis, the self-weight stress field can be generated by solving.

[0124] According to engineering geological data, the horizontal geostress lateral pressure coefficient in the vertical side wall direction of this embodiment is about 1.1, and the geostress lateral pressure coefficient in the direction of the cave axis is about 1.54. Based on the self-weight stress field obtained by solving, the stress component in the vertical side wall direction of the model area and the stress component in the direction of the cave axis are respectively set equal to the self-weight stress multiplied by the corresponding geostress lateral pressure coefficient; after the calculation is converged, the complete original rock stress field of the cave area can be obtained.

[0125] Since the surrounding rock stress field will be redistributed after the underground cavern excavation, the redistributed stress field may also affect the stability of the block. Based on the above original rock stress field, simulated excavation of the cavern area is carried out. After the calculation is converged, the stress field information of the surrounding rock after the cavern excavation is obtained, such as Fig.10 shown.

[0126] S6: Obtain the initial stable state of the block. Based on the above, the strength parameters of the bar unit are converted into actual strength parameters, and calculation and analysis are carried out. There are two situations for the final calculation results. The first is that the calculation finally converges, indicating that the block is currently in a stable state; the second is that the calculation does not converge in the end, indicating that the block is currently unstable.

[0127] For this embodiment, based on S5, the block boundary bar element is adjusted again to the bar element parameters established in S3. Then, the solution is directly obtained. If the solution fails to converge, it indicates that the initial state of the block cannot stabilize itself, that is, the block is an initially unstable block.

[0128] S7: Determination of the initial safety factor of the block. Based on S6, the strength parameters of the block structure surface are gradually reduced in equal proportion, and the strength parameters corresponding to the structural surface bar unit are adjusted. The strength reduction can be expressed by the following formula.

[0129] In this embodiment, since S6 determines that the block is an initially unstable block, when determining the initial safety factor of the block, it is necessary to continuously reduce value, carry out strength reduction analysis; according to gradually reduce After the block structure surface is completed, the bar unit parameters are calculated and analyzed respectively until the calculation results converge. Based on the strength reduction analysis of the above steps, when = 0.59, the calculation converges, indicating that the initial safety factor of the block is 0.59.

[0130] S8: Determine the block safety factor after support. For the block safety factor obtained in S7, if it does not meet the safety factor requirements specified in the specification, support measures need to be provided to stabilize the block. The support force can be applied to the free surface of the block in the form of surface force, and then the block safety factor after the support force is applied can be further analyzed using the method shown in S7 until the support force makes the block safety factor meet the requirements of the specification.

[0131] For this embodiment, the initial safety factor of the block is determined to be 0.59 based on S7, which is less than the safety factor required by the specification. Support measures need to be provided for the block so that its safety factor meets the requirements of the specification. According to the block support measures provided by the cave, a support force of 200kN can be provided for the block. The 200kN support force is applied to the free surface of the block as a uniform surface force. At this time, the calculation can converge. By repeating the strength reduction analysis of S7, the relationship between the block displacement and the safety factor during the strength reduction process can be obtained, that is, Fig.11 The strength reduction process curve shown in Figure 2 is shown in Figure 2. According to the relationship curve, when the safety factor is When the safety factor is less than 3.5, the block displacement increases but the increase is small, and the slope of the curve does not change significantly. When it is greater than 3.5, the block displacement growth rate increases and the slope of the curve increases; When it is 3.8, the calculation does not converge. Therefore, the safety factor of the block after support is determined to be 3.5, that is, under the support force of 200kN, the block has a safety factor of 3.5.

[0132] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A block stability analysis method under the framework of continuous medium numerical analysis, characterized in that: include: Establish a numerical analysis model that includes the boundary morphology of the block structure surface being analyzed; Continuously separate the block boundaries and constrain the separated grids; Apply initial constraints and initial stress to the blocks after mesh separation; Through calculation, the initial stable state of the block is obtained; The strength parameters of the block structure surface are gradually reduced in equal proportion, and the strength parameters corresponding to the structural surface bar elements are adjusted to obtain the block safety factor; When the safety factor requirements specified in the code are not met, support measures are taken to stabilize the block, and the safety factor of the block after the support force is applied is analyzed; The numerical analysis model includes the boundaries of structural surfaces constituting the block, and at least two structural surfaces constitute the block; The free surface of the block; The outer side of the block is close to the surrounding rock, and the surrounding rock range is at least 3 times the range of the block; Obtain block information that needs to be analyzed, and establish a three-dimensional numerical analysis model of the block through commercial modeling software; in the framework of continuous medium numerical analysis, the three-dimensional numerical analysis model of the block is a continuous grid, and a three-dimensional continuity numerical model is obtained; The continuous grid separation includes decomposing each node distributed on the block boundary into two nodes; after decomposing the continuous grid nodes at the block boundary, the model exhibits discontinuous characteristics at the block boundary, so that there is no interaction between the two sides of the block structure surface; The constraining of the separated grid includes introducing a rod element with dual constraints of tension, compression and shear at the boundary of the block structure surface to re-constrain the boundary of the structure surface; The bar unit can be distributed at the centroid of the mesh on both sides of each block structure surface. The bar length is the shortest length that can pass through the mesh on both sides of the structure surface. The equivalent control area of ​​each bar unit is the mesh area of ​​the surface it passes through. The tensile strength parameter and shear strength parameter of the bar unit are the structural surface strength parameter multiplied by the equivalent control area of ​​the bar unit. Normal mechanical properties of bar element: Among them, K n It represents the normal stiffness of the member unit, and its value range is 10 to 1000 times of the deformation modulus of the surrounding rock; S represents the equivalent control area of ​​the member unit; d n F represents the unit normal deformation of the member, positive represents expansion deformation, and negative represents compression deformation; n represents the normal force of the bar element, It represents the maximum normal force that can be achieved by the bar element; Tangential mechanical properties of bar elements: Among them, K s It represents the tangential stiffness of the member unit, and its value range is 10 to 1000 times of the deformation modulus of the surrounding rock; d s represents the unit tangential deformation of the member, F s represents the tangential force of the bar element, and It represents the maximum tangential force that the bar element can achieve in two tangential directions; The tensile strength and shear strength of the bar element are: Among them, t n represents the tensile strength of the block structure surface, c represents the cohesion of the block structure surface, Represents the friction angle of the block structure surface.

2. The block stability analysis method under the continuous medium numerical analysis framework according to claim 1 is characterized in that: The initial constraint application includes limiting the node displacement at the model boundary so that it remains unchanged during the calculation and analysis process; There is no constraint on the free surface of the block, and boundary normal constraints are imposed on other boundaries; The initial stress application includes assigning an initial value to the stress state of each unit of the calculation model based on the original rock stress state of the block, and calculating to a convergent state; Excavate the cavern area and obtain the stress state after redistribution after cavern excavation, which is used as the initial stress state for block analysis; The initial value assignment includes assigning a preset value to the strength parameter of the rod element during the calculation process to ensure that the rod element is in an elastic working state during the initial stress application process.

3. The block stability analysis method under the continuous medium numerical analysis framework according to claim 2 is characterized in that: The obtaining of the initial stable state of the block includes converting the strength parameters of the rod unit into actual strength parameters, performing finite element numerical simulation analysis on the numerical analysis model, and calculating two situations: The first one is to calculate the final convergence and determine that the block is currently in a stable state; The second is that the calculation does not converge in the end and it is determined that the block is currently unstable.

4. The block stability analysis method under the continuous medium numerical analysis framework according to claim 3 is characterized by: The block safety factor includes gradually reducing the strength parameters of the block structure surface in equal proportion and adjusting the strength parameters corresponding to the structure surface bar unit. The strength reduction is expressed as: t n,i =t n / SF i c i =c / SF i Among them, SF i represents the strength reduction factor; c represents the cohesion of the block structure surface, t n represents the tensile strength of the block structure surface, represents the friction angle of the block structure surface; correspondingly, c i ,t n,i , They represent the cohesion of the block structure surface after strength reduction, the tensile strength of the block structure surface, and the friction angle of the block structure surface. For the initial stable block, SF i It can be gradually increased from 1.0 until the calculation does not converge; for the initially unstable block, SF i It can be gradually reduced from 1.0 until the calculation begins to converge; The block safety factor is the SF corresponding to the critical state of block instability obtained after strength reduction. i value; The critical state of block instability is determined by the relationship curve between the displacement of the block characteristic point and the strength reduction coefficient. The critical point is characterized by a sudden increase in the slope of the curve, a sharp increase in deformation, and non-convergence of the calculation. The safety factor of the block obtained, if it does not meet the safety factor requirements, then apply for support measures to stabilize the block; The support force is implemented on the free surface of the block in the form of surface force, and the safety factor of the block after the support force is applied is re-analyzed until the support force makes the block safety factor meet the requirements of the specification.

5. A block stability analysis system in a continuous medium numerical analysis framework using the method according to any one of claims 1 to 4, characterized in that: Modeling unit, establishing a numerical analysis model including the boundary morphology of the block structure surface to be analyzed; performing continuous grid separation on the block boundary and constraining the separated grid; Run the unit to apply initial constraints and initial stress to the blocks after mesh separation; The calculation unit obtains the initial stable state of the block through calculation; The strength parameters of the block structural surface are gradually reduced in proportion, and the strength parameters corresponding to the structural surface member units are adjusted to obtain the block safety factor; when the safety factor requirements specified in the code are not met, support measures are taken to stabilize the block, and the block safety factor after the support force is applied is analyzed.

6. A computer device comprising: Memory and processor; The memory stores a computer program, wherein the processor implements the steps of any one of the methods of claims 1 to 4 when executing the computer program.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

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