Underground cavern movable block search and stability safety coefficient calculation method

Abstract

The underground cavern movable block searching and stability safety coefficient calculating method comprises the steps of 1, determining an underground cavern area needing to be calculated and analyzed, and preliminarily generating a three-dimensional calculation model of the underground cavern area; step 2, acquiring block information in surrounding rock of the underground cavern; 3, sequentially judging whether the blocks are movable blocks or not according to the block information in the step 2, and judging possible sliding damage modes of the movable blocks; step 4, calculating the sliding force and the anti-sliding force of the movable block body; step 5, calculating the stability safety coefficient of the current movable block body and outputting the stability safety coefficient; the free face is updated, and the stability safety coefficient of the next movable block continues to be calculated till the stability safety coefficients of all the movable blocks are calculated. According to the calculation method, the movable block in the surrounding rock of the underground cavern can be efficiently and quickly identified and analyzed.

Description

Technical Field

[0001] This invention belongs to the technical field of stability analysis of surrounding rock blocks in underground caverns, and specifically relates to a method for searching movable blocks and calculating the stability safety factor of underground caverns. Background Technology

[0002] Instability of movable blocks in the surrounding rock of underground caverns can cause serious engineering accidents. It is necessary to prevent the falling of movable blocks in the surrounding rock of underground caverns. Due to the complex geological conditions, it is difficult to find potentially unstable movable blocks and to provide them with reasonable anchoring support.

[0003] When using existing numerical methods such as finite element method, discrete element method, boundary element method, and DDA for rock mass analysis, it is possible to consider a limited number of faults, but it is very difficult to accurately consider the large number of joints and fissures that are not easy to measure precisely. In addition, the block structure in rock slopes is complex, often including both convex and concave blocks, but previous studies have been unable to identify concave blocks.

[0004] On the other hand, stability safety factors are usually used to identify potentially unstable movable blocks. When using stability safety factors to evaluate the stability of movable blocks, if the underground cavern area is large and the shape is complex, the number of movable blocks in the surrounding rock of the underground cavern will increase accordingly. Using traditional calculation methods, the amount of calculation is large and the calculation efficiency is low. Summary of the Invention

[0005] This invention provides a method for searching movable blocks in underground caverns and calculating their stability safety factor, in order to solve the problem of identifying and analyzing movable blocks in the surrounding rock of underground caverns.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: The method for searching movable blocks and calculating the stability safety factor of underground caverns includes the following steps: Step 1: Determine the underground cavern area to be calculated and analyzed, and generate a preliminary three-dimensional calculation model of the underground cavern area; Step 2: Obtain block information in the surrounding rock of the underground cavern. In the initially generated three-dimensional calculation model, a fracture network is generated using the Monte Carlo method, and a disk is used to simulate the spatial distribution of fractures to obtain several intersection points. By processing several intersection points, the effective edges, vector planes and vector volumes are identified in sequence. All vector volume information is the block information in the surrounding rock of the underground cavern. Step 3: Based on the block information in Step 2, determine whether each block is a movable block and determine the possible sliding failure modes of the movable blocks. Step 4: Calculate the sliding force and anti-slip force of the movable block. Step 5: Calculate and output the stability safety factor of the current movable block; update the free surface, and continue to calculate the stability safety factor of the next movable block until the stability safety factors of all movable blocks are calculated.

[0007] Furthermore, in step two, "sequentially identifying valid edges, vector planes, and vector bodies" includes the following steps: S2-1. Generate points by intersecting structural surfaces, check to find valid points, then generate edges through valid points, judge the edges to find valid edges, organize and output the information of valid edges; S2-2. Loop through the structural surface to find all edges located on the structural surface, and select the edges as the initial active edges in the loop. S2-3. The initial active edge is used twice in a loop, with the starting and ending points swapped each time, and the ending point of the active edge is used as the starting point of the new edge to be generated. S2-4. Calculate the interior angles formed by rotating all edges related to the endpoint counterclockwise with the active edge; and select the edge with the smallest interior angle as the new active edge; if the endpoint of the new active edge coincides with the point of the recorded edge, and the point is not the starting point of the initial active edge, go to step S2-3. S2-5. Calculate whether all negative vector planes are contained within a certain positive vector plane to obtain valid vector plane information; S2-6. Following the principle of rotating counterclockwise around the common edge to form the smallest interior angle, sort and combine all vector planes. When a closed system is found that satisfies the completeness of the vector body, a vector body is generated, and then the vector body information is obtained.

[0008] Furthermore, in S2-1, after generating several intersection points, it is necessary to check the validity of these intersection points to determine the valid points. The check for intersection point validity includes: Determine whether the intersection point is within the underground cavern area to be calculated by using the positional relationship between the intersection point and the boundary surface of the underground cavern area determined in step one; if the distance from the intersection point to the center of the circle is less than the radius, then the point is within the structural plane. A point is considered valid when it is located both within the underground cavern area and within the structural plane.

[0009] Furthermore, in step three, it is first determined whether the block is a free fall without a sliding surface, that is, for all non-free surfaces... have: ; In the formula, The resultant force on the block, Non-free surface Outer normal unit vector, .

[0010] Furthermore, in step three, after ruling out the possibility that the block is not free-slipping without a sliding surface, it is further determined whether the block is sliding on one side, i.e., whether there is a non-free surface. Constrain block motion, , For other non-free surfaces , , ; In the formula, The resultant force on the block, Non-free surface Outer normal unit vector, sliding force The resultant force on the block On the sliding surface Orthogonal projection on.

[0011] Furthermore, in step three, after ruling out free fall and unidirectional sliding of the block (which is not without a sliding surface), it is further determined whether the block undergoes double-sided sliding. Double-sided sliding occurs along the intersection of two planes, let the two planes be... and The direction of the intersection line is: ; In the formula, Non-free surface Outer normal unit vector, Non-free surface Outer normal unit vector, The resultant force on the block; The sign determination makes the direction of the intersection line point in the direction of possible sliding, so the sliding force is: ; If yes and Two planes have and For other non-free surfaces All , , If one face meets the condition, the block is considered to be sliding on both sides. If one face does not meet this condition, the block is not considered to be sliding on both sides.

[0012] Furthermore, in step three, it is finally determined whether the block is immovable. The criterion for determining whether a block is immovable is that an immovable block always has a non-free face. , making ,

[0013] For sliding force, Non-free surface Outer normal unit vector.

[0014] Furthermore, in step four, the formulas for calculating the total sliding force and total anti-slip force of the movable block during its free fall are: Total sliding force Total anti-skid force .

[0015] Furthermore, in step four, the total downward sliding force of the movable block sliding on one side. Total anti-skid force ; Wherein, the initial sliding surface The area is The coefficient of friction is The cohesive force is Sliding surfaces exist in each non-free plane. The area is The cohesive force is , For each non-free plane, the sliding surface Number, The normal force on the initial sliding surface can be expressed as: In the formula, The resultant force on the block, Non-free surface Outer normal unit vector.

[0016] Furthermore, in step two, the movable block slides on both sides, with the initial sliding surface... Sliding surfaces exist in each non-free plane. Total downward force Total anti-skid force ; In the formula, The direction of intersection, the initial sliding surface The area is divided into Initial sliding surface The coefficients of friction are respectively Initial sliding surface Cohesion is divided into ; Sliding surface Area is The cohesive force is ; For each non-free plane, the sliding surface Number, and These are the initial sliding surfaces. The normal force can be expressed as: ;

[0017] In the formula, Non-free surface Outer normal unit vector, Non-free surface Outer normal unit vector, Non-free surface Outer normal unit vector, The resultant force on the block, Direction of intersection Normal force on.

[0018] The present invention can achieve the following beneficial effects: 1. The calculation method of the present invention is used to overcome the shortcomings of existing calculation methods for movable blocks of surrounding rock in underground caverns. Based on automatic block identification and rigid body limit equilibrium method, it provides a method for searching movable blocks and calculating stability safety factor of underground caverns, which can effectively identify all types of blocks and determine whether the blocks are unstable and their instability mode.

[0019] 2. This invention uses fracture mesh generation technology to conveniently and effectively generate a three-dimensional random fracture network of rocks. In addition, the automatic identification of surrounding rock blocks in underground caverns introduces the concept of vector bodies, which effectively solves the problem of previous studies that could not identify concave blocks. It can find movable blocks on the surface of underground caverns as well as potential movable blocks inside the surrounding rock, with high search efficiency and accuracy.

[0020] 3. The method of this invention combines the advantages of automatic identification of movable blocks and calculation of stability safety factors. It can quickly identify possible instability and failure modes of movable blocks, calculate the stability safety factor of movable blocks under different sliding failure conditions, with clear physical meaning, rigorous derivation, and reliable calculation results, which is helpful for the stability analysis of surrounding rock masses in underground caverns. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a flowchart of the method for searching movable blocks and calculating the stability safety factor of underground caverns according to the present invention; Figure 2 This is the three-dimensional calculation model of the underground cavern area initially generated in step one of this invention; Figure 3 This is a demonstration of the model of a single vector body and the position of its free plane in step three of this invention; Figure 4 This is a rendering of the unstable movable block in the underground cavern calculated in step five of the present invention. Detailed Implementation

[0022] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0023] like Figure 1 As shown, the method for searching movable blocks and calculating the stability safety factor of underground caverns includes the following steps: Step 1: Determine the underground cavern area to be calculated and analyzed. By editing the .dat. file, input the location information of structural planes such as faults and joints, along with material properties, into the written calculation program to initially generate a three-dimensional calculation model of the underground cavern area, such as... Figure 2 As shown.

[0024] Step 2: Obtain block information in the surrounding rock of the underground cavern. In the initially generated 3D calculation model, a fracture network is generated using the Monte Carlo method, and disks are used to simulate the spatial distribution of fractures. Three or more intersecting disks will generate an intersection point. Each generated intersection point needs to undergo a validity check. Specific check steps include: using the positional relationship between the intersection point and the boundary surface of the underground cavern area determined in Step 1 to determine if the intersection point is within the required calculation area; and using a distance comparison method to determine if the point is located within the structural plane. If the distance from the intersection point to the center of the circle is less than the radius, then the point is within the structural plane.

[0025] A point is considered valid when it is located both within the underground cavern area and within the structural plane. Two valid points will generate an edge, different edges will form a vector plane, and different vector planes will form a vector body. Finally, the generated edges, vector planes, and vector bodies are identified by the program, and valid edges, valid vector planes, and valid vector bodies are selected to obtain the information of the block. The specific identification method is as follows; S21. Edge Identification: Sort all intersection points on the same straight line to generate all edges, and simultaneously determine the validity of each edge. If an intersection point is only related to two edges, and these two edges are collinear, merge them into one edge, and then update the topological relationships of intersection points and lines. If a point corresponding to an edge is only related to that edge, then both the edge and the point are invalid, and the number of related edges for the other point corresponding to that edge is decremented by 1. Repeat this process to delete all isolated edges. After completing the previous step, proceed to the next step. If all related edges of a point selected in the previous steps are on the same plane, then both the point and the edge are invalid. Finally, organize and output the information of all valid edges. S22. Vector Surface Recognition: After generating the information of all valid edges, the data structure information of the vector surface can be generated. The vector surface recognition steps are as follows: S22-1 Input the information of valid edges, loop through the structure surface, find all valid edges on the structure surface, and select all valid edges on the structure surface as the initial active edges. S22-2 To find all valid edges related to the initial active edge, the initial active edge is used twice in a loop, with the starting and ending points swapped each time, and the ending point of the active edge is used as the starting point of the new edge to be generated. S22-3 When there are multiple edges related to the endpoint of the active edge, calculate the interior angle formed by rotating all edges related to the endpoint and the active edge counterclockwise, and select the edge with the smallest interior angle as the new active edge; if the endpoint of the new active edge coincides with the point of the recorded edge, and the point is not the starting point of the initial active edge, go to step S22-2. S22-4 calculates whether all negative vector planes are contained within a certain positive vector plane. If so, the positive vector plane is a composite vector plane; otherwise, the negative vector plane is an invalid vector plane. Invalid vector planes are deleted, and the information of valid vector planes is organized and output.

[0026] S23 Vector Recognition: For all identified vector surfaces, according to the principle of rotating counterclockwise around the common edge to form the smallest interior angle, sort and combine them end to end. When a vector surface combination is closed and satisfies the completeness of the vector (a set of vectors can completely represent all the information of a vector), a vector is generated, and then the vector information is obtained.

[0027] In addition, since irregular terrain surfaces need to be considered, curved edges will appear. Therefore, only two edges may be needed to form a vector plane. In this case, the curved edges can be replaced by straight edges passing through the two endpoints of the curved edges, which can be transformed into the generation of ordinary vector planes.

[0028] Similarly, all the vector surfaces on the terrain surface are curved surfaces, and the terrain surface is written as... The function form, yes and A single-valued function can project a terrain surface onto a horizontal plane, and the relative positions of the points and edges on it will not change, thus generating a vector plane on the terrain surface.

[0029] Step 3: Obtain the movable blocks within the surrounding rock mass and determine the possible sliding failure modes of the movable blocks. For example... Figure 3 As shown, calculate the movable block's... , , Determine whether the non-free planes constrain the falling trend of the block, whether the block is movable, and calculate the mutual constraint between the sliding surfaces to determine the sliding failure mode.

[0030] Specifically, information about all blocks has been identified in step two. However, there are various types of blocks. The following steps are taken to determine whether a block is a movable block and its possible sliding failure modes: S31. Determine if it is a free fall without a slip surface: For all non-free surfaces ,have

[0031] In the formula, The resultant force on the block, Non-free surface Outer normal unit vector, .

[0032] S32. Determine if it is a one-sided sliding: There exists a non-free surface. Constrain block motion, For other non-free surfaces , , ; In the formula, the sliding force To work together On the sliding surface orthographic projection on Non-free surface Outer normal unit vector.

[0033] S33. Determine if it is a two-sided slide: A two-sided slide slides along the intersection of two planes, let these two planes be... and The direction of the intersection line is: ; The sign determination makes the direction of the intersection line point in the direction of possible sliding, so the sliding force is: ; If yes and Two planes have and For other non-free surfaces All , , If the block is slidable on both sides, then if one of the sides does not meet this condition, then we continue to determine whether it is a non-movable block.

[0034] S34. Determine whether a block is immovable. Criteria: For There is always a non-free surface. , , .

[0035] Step 4: Calculate the sliding force and anti-slip force of the movable block: The product of the normal force and the tangent of the internal friction angle, plus the sum of the cohesive forces, is the total anti-slip force of the sliding surface. The total sliding force is the sum of the tangential forces on the sliding surface or the sliding line.

[0036] The following steps are used to calculate the total sliding force and total anti-slip force of the movable block under different sliding modes: S41. Formulas for calculating total sliding force and total anti-slip force when a movable block detaches freely: Total downward force Total anti-skid force ; S42. The movable block slides on one side, with the initial sliding surface... In each non-free plane there exists sliding surface Formulas for calculating total sliding force and total anti-skid force: Total downward force Total anti-skid force ; In the formula, the initial sliding surface Area is The coefficient of friction is The cohesive force is Sliding surfaces exist in each non-free plane. The area is The cohesive force is , For each non-free plane, the sliding surface Number, , The normal force on the initial sliding surface can be expressed as: ; S43. Movable block slides on both sides, initial sliding surface In each non-free plane there exists or sliding surface Formulas for calculating total sliding force and total anti-skid force: Total downward force Total anti-skid force ; In the formula, the initial sliding surface Area divided into Initial sliding surface The coefficients of friction are respectively Initial sliding surface Cohesion is divided into ; Sliding surface Area is The cohesive force is ; For each non-free plane, the sliding surface Number, and These are the initial sliding surfaces. The normal force can be expressed as: ; ; In the formula, Non-free surface Outer normal unit vector, Non-free surface Outer normal unit vector, Non-free surface Outer normal unit vector, The resultant force on the block, Direction of intersection Normal force on.

[0037] Step 5: Calculate the stability safety factor of the movable block, update the free surface, and proceed to Step 3.

[0038] Based on the parameters obtained in the above steps, the stability safety factor of the movable block can be calculated. Update the free surface and proceed to step three to calculate the stability safety factor of the next movable block. Repeat this process until the stability safety factor calculation for all movable blocks is completed.

[0039] Using the calculation method of this application, the movable blocks of the underground cavern can be divided and identified through steps one and two, and then the stability safety factor of each movable block can be quickly calculated through steps three to five, thereby enabling the determination of whether each movable block in the underground cavern is unstable. Figure 4 As shown, it is ultimately possible to identify unstable blocks in the surrounding rock of underground caverns.

[0040] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for searching movable blocks and calculating the stability safety factor of underground caverns, characterized in that, Includes the following steps: Step 1: Determine the underground cavern area to be calculated and analyzed, and generate a preliminary three-dimensional calculation model of the underground cavern area; Step 2: Obtain block information in the surrounding rock of the underground cavern. In the initially generated three-dimensional calculation model, a fracture network is generated using the Monte Carlo method, and a disk is used to simulate the spatial distribution of fractures to obtain several intersection points. By processing several intersection points, the effective edges, vector planes and vector volumes are identified in sequence. All vector volume information is the block information in the surrounding rock of the underground cavern. Step 3: Based on the block information in Step 2, determine whether each block is a movable block and determine the possible sliding failure modes of the movable blocks. Step 4: Calculate the sliding force and anti-slip force of the movable block. Step 5: Calculate and output the stability safety factor of the current movable block; update the free surface, and continue to calculate the stability safety factor of the next movable block until the stability safety factors of all movable blocks are calculated.

2. The method for searching movable blocks and calculating the stability safety factor of underground caverns according to claim 1, characterized in that: In step two, "sequentially identifying the valid edges, vector planes, and vector bodies" includes the following steps: S2-1. Generate points by intersecting structural surfaces, check to find valid points, then generate edges through valid points, judge the edges to find valid edges, organize and output the information of valid edges; S2-2. Loop through the structural surface to find all edges located on the structural surface, and select the edges as the initial active edges in the loop. S2-3. The initial active edge is used twice in a loop, with the starting and ending points swapped each time, and the ending point of the active edge is used as the starting point of the new edge to be generated. S2-4. Calculate all interior angles formed by counterclockwise rotation of the active edge related to the endpoint; and select the edge with the smallest interior angle as the new active edge; if the endpoint of the new active edge coincides with the point of the recorded edge, and the point is not the starting point of the initial active edge, go to step S2-3. S2-5. Calculate whether all negative vector planes are contained within a certain positive vector plane to obtain valid vector plane information; S2-6. Following the principle of rotating counterclockwise around the common edge to form the smallest interior angle, sort and combine all vector planes. When a closed system is found that satisfies the completeness of the vector body, a vector body is generated, and then the vector body information is obtained.

3. The method for searching movable blocks and calculating the stability safety factor of underground caverns according to claim 2, characterized in that: In S2-1, after generating several intersection points, it is necessary to check the validity of these intersection points to determine the valid points. The check for intersection point validity includes: Determine whether the intersection point is within the underground cavern area to be calculated by using the positional relationship between the intersection point and the boundary surface of the underground cavern area determined in step one; if the distance from the intersection point to the center of the circle is less than the radius, then the point is within the structural plane. A point is considered valid when it is located both within the underground cavern area and within the structural plane.

4. The method for searching movable blocks and calculating the stability safety factor of underground caverns according to claim 1, characterized in that: In step three, the first step is to determine whether the block is a free fall without a sliding surface, that is, for all non-free surfaces. have: ； In the formula, The resultant force on the block, Non-free surface Outer normal unit vector, .

5. The method for searching movable blocks and calculating the stability safety factor of underground caverns according to claim 4, characterized in that: In step three, after ruling out the possibility that the block is not free-slipping without a sliding surface, it is further determined whether the block is sliding on one side, i.e., whether there is a non-free surface. Constrain block motion, , ; For other non-free surfaces , ， ； In the formula, The resultant force on the block, Non-free surface Outer normal unit vector, sliding force The resultant force on the block On the sliding surface Orthogonal projection on.

6. The method for searching movable blocks and calculating the stability safety factor of underground caverns according to claim 5, characterized in that: In step three, after ruling out free fall and unidirectional sliding of the block (which is not without a sliding surface), the next step is to determine whether the block is sliding on two sides. Double-sided sliding occurs along the intersection of two planes, which are denoted as (1) and (2) respectively. and The direction of the intersection line is: ； In the formula, Non-free surface Outer normal unit vector, Non-free surface Outer normal unit vector, The resultant force on the block; The sign determination makes the direction of the intersection line point in the direction of possible sliding, so the sliding force is: ； If yes and Two planes have and ; For other non-free surfaces All , , If one face meets the condition, the block is considered to be sliding on both sides. If one face does not meet this condition, the block is not considered to be sliding on both sides.

7. The method for searching movable blocks and calculating the stability safety factor of underground caverns according to claim 6, characterized in that: In step three, the final determination is whether the block is immovable. The criterion for determining whether a block is immovable is that it always has a non-free face. , making ， For sliding force, Non-free surface Outer normal unit vector.

8. The method for searching movable blocks and calculating the stability safety factor of underground caverns according to claim 4, characterized in that: In step four, the formulas for calculating the total sliding force and total anti-slip force of the movable block during its free fall are: Total sliding force Total anti-skid force .

9. The method for searching movable blocks and calculating the stability safety factor of underground caverns according to claim 5, characterized in that: In step four, the total sliding force of the movable block sliding on one side Total anti-skid force ; Wherein, the initial sliding surface The area is The coefficient of friction is The cohesive force is Sliding surfaces exist in each non-free plane. The area is The cohesive force is , For each non-free plane, the sliding surface Number, The normal force on the initial sliding surface can be expressed as: In the formula, The resultant force on the block, Non-free surface Outer normal unit vector.

10. The method for searching movable blocks and calculating the stability safety factor of underground caverns according to claim 7, characterized in that: In step two, the movable block slides on both sides, with the initial sliding surface... Sliding surfaces exist in each non-free plane. Total downward force Total anti-skid force ; In the formula, The direction of intersection, the initial sliding surface The area is divided into Initial sliding surface The coefficients of friction are respectively Initial sliding surface Cohesion is divided into ; Sliding surface Area is The cohesive force is ; For each non-free plane, the sliding surface Number, and These are the initial sliding surfaces. The normal force can be expressed as: ； In the formula, Non-free surface Outer normal unit vector, Non-free surface Outer normal unit vector, Non-free surface Outer normal unit vector, The resultant force on the block, Direction of intersection Normal force on.

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