A method for automatically searching and stability evaluation of key dangerous block in hydraulic tunnel

Abstract

The application discloses a method for automatically searching and evaluating stability of key dangerous blocks in a hydraulic tunnel, which comprises the following steps: constructing a three-dimensional model of the tunnel and automatically identifying all blocks based on a spatial topology algorithm; calculating the safety factor of the blocks by using a rigid body limit equilibrium method, and determining the blocks below a threshold value as dangerous blocks; supporting the exposed excavation surface of the dangerous blocks, calculating the safety factor after supporting, and comparing the safety factor with the threshold value; if the safety factor after supporting is still below the threshold value, adjusting the number of supporting points and repeating the calculation until the requirement is met; and finally outputting the block number, supporting parameters and sliding mode. The method can automatically identify dangerous blocks and optimize the supporting scheme, ensure that the stability of the reinforced blocks meets the requirements, and improve the intelligent level of the tunnel supporting design.

Description

Technical Field

[0001] This invention belongs to the field of tunnel hazardous block monitoring technology, specifically relating to an automatic search and stability assessment method for key hazardous blocks in hydraulic tunnels. Background Technology

[0002] During the excavation of underground caverns, such as deep-buried hydraulic tunnels and cavern complexes, various structural planes, including joints, bedding, and faults, are commonly found within the rock mass. These structural planes can easily combine to form potentially unstable blocks. When the shear strength of a structural plane is lower than the sliding force of the block, the block is highly susceptible to slippage, collapse, and other instability phenomena, seriously threatening the safety and stability of underground cavern construction. Therefore, to ensure the stability of the surrounding rock of underground caverns after excavation, engineering practice typically requires accurate prediction of the location of potentially unstable blocks before construction and the implementation of targeted support measures such as anchor bolts and anchor cables.

[0003] In existing technologies, block theory-based analysis methods have been widely applied to the prediction and stability analysis of unstable blocks at different excavation faces. For example, the critical block theory proposed by Goodman et al. can identify block types based on the combination characteristics of rock mass structural planes and estimate their safety factors by calculating the geometric characteristics and mechanical parameters of the blocks. However, such analysis methods often rely on manual identification of structural plane combinations and idealized calculations. For large hydraulic tunnels with complex structural plane distributions, manually identifying all dangerous blocks is not only time-consuming and laborious but also prone to overlooking critical structural plane combinations, leading to biased analysis results.

[0004] To address the shortcomings of existing technologies, there is an urgent need to develop an algorithm that can automatically search for unstable blocks at the excavation face of hydraulic tunnels in a three-dimensional model and quickly calculate their safety factor. This would improve the efficiency and reliability of unstable block analysis and provide strong protection for the safety of underground structure construction. Summary of the Invention

[0005] This invention proposes an automatic search and stability assessment method for critical hazardous blocks in hydraulic tunnels. It can automatically identify hazardous blocks, support them, calculate the safety factor after support, and compare it with a preset threshold. When the safety factor after support is lower than the threshold, the number of rows and columns of support points will be adjusted until the safety factor after support is greater than the preset threshold requirement.

[0006] To achieve the above objectives, the present invention proposes the following technical content:

[0007] An automatic search and stability assessment method for critical hazardous blocks in hydraulic tunnels includes:

[0008] S1: Construct a 3D model of the hydraulic tunnel and automatically identify all blocks based on a spatial topology analysis algorithm;

[0009] S2: The stability safety factor of the block under unsupported conditions is calculated using the rigid body limit equilibrium method;

[0010] S3: When the unsupported safety factor of the qth candidate block is less than the set unsupported safety factor threshold, the block is regarded as a dangerous block under unsupported conditions;

[0011] S4: When the block is a dangerous block, its exposed excavation face shall be supported;

[0012] S5: Calculate the stability safety factor of the q-th candidate block under the support conditions;

[0013] S6: Compare the stability safety factor of the qth candidate block with the unsupported safety factor threshold in step S3. When the stability safety factor of the qth candidate block is less than the unsupported safety factor threshold, change the number of rows and columns of the support points in S4, and repeat S4-S6 until the stability safety factor of the qth candidate block is greater than or equal to the unsupported safety factor threshold.

[0014] S7: Summary output; outputs the number of all candidate blocks, the number of rows and columns of support points, and the sliding method information.

[0015] Furthermore, in step S2, the number of sliding surfaces of each candidate block is determined by traversing each candidate block; including: single sliding surface, two sliding surfaces, and those that do not have the kinematic conditions to slide out towards the open space of the cavern.

[0016] Furthermore, when the block is a single-slip surface block, the unsupported safety factor is calculated in two cases;

[0017] First case: Unsupported safety factor under basic combined working conditions for a single sliding block;

[0018]

[0019] In the formula, This represents the unsupported safety factor of the qth candidate block under the basic combined working condition when the block is a single-slip surface block. Indicates the internal friction angle of the rock mass on the slip surface; Indicates the cohesive force of the smooth surface; This represents the component of the force exerted by groundwater on the normal direction of the slip surface; This represents the component of the force exerted by groundwater along the sliding direction; This represents the weight of the q-th candidate block; Represents the area of ​​the smooth surface; Indicates the angle of inclination of the slip surface;

[0020] The second scenario: for single-slip surface blocks, the unsupported safety factor is considered in the case of accidental combinations of working conditions such as seismic action;

[0021]

[0022] In the formula, This represents the unsupported safety factor of the qth candidate block under accidental combination conditions when the block is a single-slip surface block. Indicates the horizontal acceleration due to seismic action; Represents gravitational acceleration; Indicates the angle of inclination of the slip surface; Indicates the cohesive force of the smooth surface; This represents the weight of the q-th candidate block; This represents the component of the force exerted by groundwater on the normal direction of the slip surface; This represents the component of the force exerted by groundwater along the sliding direction; Indicates the internal friction angle of the rock mass on the slip surface; This represents the area of ​​the smooth surface.

[0023] Furthermore, when the block is a two-slip surface block, the unsupported safety factor is calculated in two cases;

[0024] First case: When there are two sliding blocks, the unsupported safety factor under the basic combined working condition;

[0025] First, calculate the normal forces on the two sliding surfaces:

[0026]

[0027]

[0028] In the formula, This represents the normal force of the q-th candidate block on the sliding surface i; This represents the normal force of the q-th candidate block on the sliding surface j; Indicates the angle between the sliding surface i and the vertical auxiliary surface; This represents the angle between the sliding surface j and the vertical auxiliary surface; This represents the angle between sliding surface i and sliding surface j; and Let i and j represent the uplift pressure of groundwater, respectively. Indicates the angle of inclination of the line of intersection between sliding surfaces i and j; This represents the weight of the q-th candidate block;

[0029] Next, calculate the unsupported safety factor of the double-slip surface block:

[0030]

[0031] In the formula, When representing a double-slip surface block, it represents the unsupported safety factor of the qth candidate block under the basic combined working condition; Indicates the internal friction angle of the rock surface i; Indicates the internal friction angle of the rock surface j; This represents the cohesive force of the slip surface i; This represents the cohesive force of the slip surface j; and Let i and j represent the areas of the sliding surfaces, respectively. This represents the resultant force of groundwater acting along the intersection of slip surface i and slip surface j; Indicates the angle of inclination of the line of intersection between sliding surfaces i and j; This represents the weight of the q-th candidate block; This represents the normal force of the q-th candidate block on the sliding surface i; This represents the normal force of the q-th candidate block on the sliding surface j;

[0032] The second scenario: considering the unsupported safety factor for accidental combinations of working conditions such as earthquakes;

[0033] First, calculate the normal forces on the two sliding surfaces:

[0034]

[0035] In the formula, This represents the normal force of the q-th candidate block on the sliding surface i; This represents the normal force of the q-th candidate block on the sliding surface j; Indicates the angle between the sliding surface i and the vertical auxiliary surface; This represents the angle between the sliding surface j and the vertical auxiliary surface; This represents the angle between sliding surface i and sliding surface j; and Let i and j represent the uplift pressure of groundwater, respectively. Indicates the angle of inclination of the line of intersection between sliding surfaces i and j; This represents the weight of the q-th candidate block; Indicates the horizontal acceleration due to seismic action;

[0036] In calculating the safety factor for unsupported structures:

[0037]

[0038] In the formula, This represents the unsupported safety factor for a double-sliding wedge-shaped block under accidental combination working conditions. This represents the normal force of the q-th candidate block on the sliding surface i; This represents the normal force of the q-th candidate block on the sliding surface j; The internal friction angle of surface i is represented; This represents the internal friction angle of the slip surface j; This represents the resultant force of groundwater acting along the intersection of slip surface i and slip surface j; and Let i and j represent the cohesion of the sliding surfaces, respectively. and Let i and j represent the areas of the sliding surfaces, respectively.

[0039] Further, step S4 includes the following steps:

[0040] S4.1: Select three non-collinear points A, B, and C on the exposed excavation face and construct a local coordinate system;

[0041] S4.2: Using the origin of the local coordinate system As the reference center for the arrangement of the support point array, in and An array of anchor bolts or anchor cables is generated in the local plane of the exposed excavation face of Zhangcheng; assuming that a total of anchor bolts or anchor cables are arranged on the q-th candidate block. OK, The row spacing of the anchor bolts or anchor cables is as follows: The column spacing is ;

[0042] line number is recorded as The column number is denoted as ,and , For the first line, number The coordinates of the support points of the column in the local coordinate system are:

[0043]

[0044] In the formula, This represents the three-dimensional coordinates of the support point in the r-th row and b-th column on the q-th candidate block;

[0045] Then the coordinates of the support point in the r-th row and b-th column of the q-th candidate block in the global coordinate system of the 3D model It can be calculated using the following formula:

[0046]

[0047] In the formula, These represent the three coordinate components of the support point in the r-th row and b-th column of the q-th candidate block in the global coordinate system of the 3D model, respectively. These are the coordinates of the support point in the local coordinate system; These are the coordinates of the origin of the local coordinate system in the global coordinate system. ; These are the three unit basis vectors of the local coordinate system relative to the global coordinate system. .

[0048] Further, step S5 includes the following steps:

[0049] S5.1: Calculate the effective component of the force at the m-th support point of the g-th candidate block in the anti-slip direction;

[0050]

[0051] In the formula, This represents the effective component of the anti-slip force at the m-th support point of the g-th candidate block in the anti-slip direction; This represents the axial support force at the m-th support point; This represents the unit axial direction vector of the m-th support point of the g-th candidate block; Represents the unit vector of the potential sliding direction of the g-th candidate block;

[0052] S5.2: Calculate the total effective support anti-slip force of the g-th candidate block;

[0053]

[0054] In the formula, This represents the total effective support and anti-slip force of the g-th candidate block; Indicates the number of anchor bolts used for support;

[0055] S5.3: Calculate the anti-slip force of the g-th candidate block;

[0056] The formula is:

[0057]

[0058] In the formula, This represents the total anti-slip force of the q-th candidate block in the potential sliding direction when unsupported; This represents the anti-slip force of the q-th candidate block;

[0059] S5.4: Calculate the stability safety factor under the support condition of the g-th candidate block;

[0060]

[0061] In the formula, This represents the total sliding force under the support condition of the q-th candidate block; It represents the stability safety factor under the support condition of the q-th candidate block.

[0062] Furthermore, step S5 discusses the total sliding force along the potential slip direction under support conditions in two cases:

[0063] First scenario: Under supported conditions, if the anchor bolts or cables only provide anti-slip effect and do not generate an unfavorable component force along the potential sliding direction, then:

[0064]

[0065] In the formula, This represents the total sliding force of the q-th candidate block along the potential sliding direction under support conditions;

[0066] The second scenario: If each support point has an unfavorable component force along the potential sliding direction, then this unfavorable component force is included in the total sliding force under the support conditions; this can be expressed as:

[0067]

[0068] In the formula, This represents the adverse force generated at the m-th support point along the potential sliding direction; This represents the number of support points on the q-th candidate block.

[0069] The beneficial effects that can be achieved by adopting the above technologies are:

[0070] First, the safety factor of the unsupported block is compared with a set threshold. If the safety factor is less than the set threshold, the block is determined to be a dangerous block. If the block is a dangerous block, the excavation face of the block is supported, and the safety factor after support is calculated. The safety factor after support is compared with the set threshold. If the safety factor is less than the set threshold, the number of rows and columns of anchor bolts is readjusted until the safety factor is greater than or equal to the set threshold. Attached Figure Description

[0071] Figure 1 This is a schematic diagram of a double-smooth block;

[0072] Figure 2 This is a schematic diagram showing the selection of sliding surfaces and intersection points during the calculation of the support safety factor for double-sliding block structures.

[0073] Figure 3 This is a schematic diagram showing the relative positions of the anchor bolt / anchor cable and the block in space;

[0074] Figure 4 This is a schematic diagram showing the distribution of candidate blocks for hydraulic tunnels. Detailed Implementation

[0075] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0076] A method for automatic search and stability assessment of critical hazardous blocks in hydraulic tunnels, comprising the following steps:

[0077] S1: Construct a 3D model of the hydraulic tunnel and automatically identify all blocks based on a spatial topology analysis algorithm.

[0078] Specifically, based on the design CAD drawings of the hydraulic tunnel and geological survey data, a three-dimensional geological model of the hydraulic tunnel and its surrounding rock mass is constructed in a three-dimensional modeling environment. The constructed three-dimensional geological model must fully include the tunnel excavation boundary surface and various major rock mass structural surfaces (such as joints, faults, bedding, etc.) distributed in the site, so as to realistically restore the spatial layout characteristics of the tunnel and the occurrence and location information of each structural surface.

[0079] During the modeling process, based on the spatial topology analysis algorithm, the geometric combinations of all possible blocks formed by structural surfaces and excavation surfaces are automatically traversed:

[0080] 1. Based on the relative positional relationship between the structural surface combination and the excavation face of the cavern: When several structural surfaces intersect each other and together form a closed polyhedron around the excavation free face, it is determined whether the combination can form a block; for each structural surface combination that meets the closure condition, the algorithm automatically generates the corresponding three-dimensional solid model of the block using three-dimensional Boolean operations, and ensures that the resulting block is a closed polyhedral geometry without holes or openings.

[0081] 2. Each generated block is an independent NURBS 3D solid, and the structural surface set information that makes up the block is recorded;

[0082] S2: The stability safety factor of the block under unsupported conditions is calculated using the rigid body limit equilibrium method. This includes the following steps:

[0083] S2.1: Determine the number of sliding surfaces for each candidate block;

[0084] Specifically, for the q-th candidate block, the number of its sliding surfaces is determined by traversal, including the following three cases: single sliding surface, two sliding surfaces, and no kinematic conditions for sliding out towards the open space of the cavern.

[0085] S2.2: When the block is a single-slip surface block, the unsupported safety factor is calculated in two cases;

[0086] Case 1: Unsupported safety factor under the basic combined working condition for a single sliding block. See [link to relevant parameter definitions] for the meanings of the parameters. Figure 1 .

[0087]

[0088] In the formula, This represents the unsupported safety factor of the qth candidate block under the basic combined working condition when the block is a single-slip surface block. The internal friction angle of the rock surface represents the slip surface; This represents the cohesion of the rock mass at the slip surface; This represents the component of the force exerted by groundwater on the normal direction of the slip surface; This represents the component of the force exerted by groundwater along the sliding direction; This represents the weight of the q-th candidate block; Represents the area of ​​the smooth surface; Indicates the angle of inclination of the slip surface.

[0089] The second scenario: For single-slip surface blocks, the unsupported safety factor is considered in the case of accidental combinations of working conditions such as seismic action.

[0090]

[0091] In the formula, This represents the unsupported safety factor of the qth candidate block under accidental combination conditions when the block is a single-slip surface block. Indicates the horizontal acceleration due to seismic action; Represents gravitational acceleration; Indicates the angle of inclination of the slip surface; This represents the cohesion of the rock mass at the slip surface; This represents the weight of the q-th candidate block; This represents the component of the force exerted by groundwater on the normal direction of the slip surface; This represents the component of the force exerted by groundwater along the sliding direction; The internal friction angle of the rock surface represents the slip surface; This represents the area of ​​the smooth surface.

[0092] S2.3: When the block is a two-slip surface block, the unsupported safety factor is calculated in two cases; for example... Figure 2 As shown.

[0093] Case 1: The unsupported safety factor under the basic combined working condition when there are two sliding blocks.

[0094] First, calculate the normal forces on the two sliding surfaces:

[0095]

[0096]

[0097] In the formula, This represents the normal force of the q-th candidate block on the sliding surface i; This represents the normal force of the q-th candidate block on the sliding surface j; Indicates the angle between the sliding surface i and the vertical auxiliary surface; This represents the angle between the sliding surface j and the vertical auxiliary surface; This represents the angle between sliding surface i and sliding surface j; and Let i and j represent the uplift pressure of groundwater, respectively. Indicates the angle of inclination of the line of intersection between sliding surfaces i and j; This represents the weight of the q-th candidate block.

[0098] Next, calculate the unsupported safety factor of the double-slip surface block:

[0099]

[0100] In the formula, When representing a double-slip surface block, it represents the unsupported safety factor of the qth candidate block under the basic combined working condition; Indicates the internal friction angle of the rock surface i; Indicates the internal friction angle of the rock surface j; This represents the cohesive force of the slip surface i; This represents the cohesive force of the slip surface j; and Let i and j represent the areas of the sliding surfaces, respectively. This represents the resultant force of groundwater acting along the intersection of slip surface i and slip surface j; Indicates the angle of inclination of the line of intersection between sliding surfaces i and j; This represents the weight of the q-th candidate block; This represents the normal force of the q-th candidate block on the sliding surface i; This represents the normal force of the q-th candidate block on the sliding surface j.

[0101] The second scenario: Considering the unsupported safety factor for accidental combinations of working conditions such as earthquakes.

[0102] First, calculate the normal forces on the two sliding surfaces:

[0103]

[0104] In the formula, This represents the normal force of the q-th candidate block on the sliding surface i; This represents the normal force of the q-th candidate block on the sliding surface j; Indicates the angle between the sliding surface i and the vertical auxiliary surface; This represents the angle between the sliding surface j and the vertical auxiliary surface; This represents the angle between sliding surface i and sliding surface j; and Let i and j represent the uplift pressure of groundwater, respectively. Indicates the angle of inclination of the line of intersection between sliding surfaces i and j; This represents the weight of the q-th candidate block; Indicates the horizontal acceleration due to seismic action;

[0105] Then calculate the safety factor for the unsupported area:

[0106]

[0107] In the formula, This indicates the safety factor for a double-slip surface block under accidental combination working conditions without support. This represents the normal force of the q-th candidate block on the sliding surface i; This represents the normal force of the q-th candidate block on the sliding surface j; Indicates the internal friction angle of the rock surface i; Indicates the internal friction angle of the rock surface j; This represents the resultant force of groundwater acting along the intersection of slip surface i and slip surface j; and Let i and j represent the cohesion of the sliding surfaces, respectively. and Let i and j represent the areas of the sliding surfaces, respectively.

[0108] S3: When the unsupported safety factor of the qth candidate block is less than the set unsupported safety factor threshold, the block is considered as a dangerous block under unsupported conditions.

[0109] Specifically,

[0110] when When this condition is considered, it indicates that the single-sided sliding block is a dangerous block when considering the basic combined working conditions;

[0111] when This indicates that under accidental combination of working conditions, the single-sided sliding block is a dangerous block;

[0112] when When this condition is considered, it indicates that the double-slip surface block is a dangerous block when considering the basic combined working conditions;

[0113] when This indicates that the double-slip surface block is a dangerous block under accidental combination of working conditions;

[0114] In the formula, This indicates the set threshold for the unsupported safety factor, which is set to 1.8~2.0; This indicates that the smaller of the two options is taken.

[0115] S4: When the block is a hazardous block, its exposed excavation face shall be supported. This includes the following steps:

[0116] S4.1: Select three non-collinear points A, B, and C on the exposed excavation face to construct a local coordinate system; then the origin of the local coordinate system is:

[0117]

[0118] The basis vectors of the local coordinate system are:

[0119]

[0120]

[0121]

[0122] In the formula, and This represents two mutually orthogonal unit basis vectors; This represents the normal unit basis vector of the excavation face.

[0123] The aforementioned basis vectors are used to establish the local coordinate system of the exposed excavation face, where and The layout plan of anchor bolts or anchor cables (hereinafter referred to as support points), This indicates the normal direction of the plane in which the anchor bolts are arranged. In subsequent steps, the local coordinates of the support points are first calculated in this local coordinate system based on the number of rows, columns, and spacing. Then, the local coordinates are converted into global coordinates in the three-dimensional model using basis vectors, thereby determining the actual arrangement position of the anchor bolts or anchor cables in space.

[0124] S4.2: Using the origin of the local coordinate system As the reference center for the arrangement of the support point array, in and An array of anchor bolts or anchor cables is generated within a local plane of the exposed excavation face of Zhangcheng. Assume a total of [number missing] anchor bolts or anchor cables are deployed on the q-th candidate block. OK, The row spacing of the anchor bolts or anchor cables is as follows: The column spacing is The line number is denoted as The column number is denoted as ,and , The location of each support point is determined by the local coordinate formula described below.

[0125] For the line, number The coordinates of the support points of the column in the local coordinate system can be expressed as:

[0126]

[0127] In the formula, This represents the three-dimensional coordinates of the support point in the r-th row and b-th column of the q-th candidate block in the local coordinate system.

[0128] Specifically, let the coordinates of the origin of the local coordinate system in the global coordinate system of the 3D model be:

[0129]

[0130] The calculated basis vectors of the local coordinate system are as follows:

[0131]

[0132] Then the coordinates of the support point in the r-th row and b-th column of the q-th candidate block in the global coordinate system of the 3D model It can be calculated using the following formula:

[0133]

[0134] In the formula, These represent the three coordinate components of the support point in the r-th row and b-th column of the q-th candidate block in the global coordinate system of the 3D model, respectively. Let be the coordinates of the support point in the r-th row and b-th column of the q-th candidate block in the local coordinate system; These are the coordinates of the origin of the local coordinate system in the global coordinate system. These are the three unit basis vectors of the local coordinate system relative to the global coordinate system. Through the above coordinate transformation, the support points generated in the local plane of the excavation face can be accurately mapped to the three-dimensional model.

[0135] In this embodiment, for example, the anchor bolts are evenly arranged in 3 rows × 5 columns. , ;like Figure 3 As shown.

[0136] S5: Calculate the stability safety factor of the q-th candidate block under the support conditions. This includes the following steps:

[0137] S5.1: Calculate the effective component of the force at the m-th support point of the q-th candidate block in the anti-slip direction;

[0138]

[0139] In the formula, This represents the effective component of the force at the m-th support point of the q-th candidate block in the anti-slip direction; This represents the axial support force at the m-th support point; This represents the unit axial direction vector of the m-th support point of the q-th candidate block; Represents the unit vector of the potential sliding direction of the q-th candidate block; This indicates taking the larger value.

[0140] S5.2: Calculate the total effective support anti-slip force of the qth candidate block.

[0141]

[0142] In the formula, This represents the total effective support and anti-slip force of the q-th candidate block; Indicates the number of support points;

[0143] S5.3: Calculate the total anti-slip force of the q-th candidate block under the support conditions.

[0144] The total anti-slip force of the q-th candidate block under unsupported conditions is denoted as . This value is obtained from the unsupported stability calculation in step S2. Specifically, This is the numerator of the formula for the unsupported safety factor under basic or accidental combination of single-slip surface working conditions.

[0145] Under supported conditions, the total effective support anti-sliding force provided by anchor bolts or anchor cables Taking into account the anti-slip force term, the total anti-slip force under the support condition of the qth candidate block is:

[0146]

[0147] In the formula, The total anti-slip force of the q-th candidate block along the potential sliding direction under unsupported conditions is calculated from the unsupported stability in step S2. This represents the total effective anti-slip force provided by all support points on the q-th candidate block along the anti-slip direction; It represents the total anti-slip force of the q-th candidate block along the potential sliding direction under support conditions.

[0148] S5.4: Calculate the stability safety factor of the q-th candidate block under support conditions.

[0149] Specifically,

[0150] First, calculate the total sliding force of the q-th candidate block along the potential sliding direction under unsupported conditions, denoted as . This value is not an independent input parameter, but is determined by the unsupported stability calculation formula under the corresponding slip mode and working condition combination in step S2.

[0151] For a single smooth surface block Take the denominator term in the formula for the safety factor of a single unsupported sliding surface, and decide whether to consider only the basic combination of working conditions or the accidental combination of working conditions based on the actual situation.

[0152] For double-smooth blocks Take the denominator term in the formula for the safety factor of unsupported double sliding surfaces, and decide whether to consider only the basic combination of working conditions or the accidental combination of working conditions based on the actual situation.

[0153] Then, we discuss the total sliding force along the potential slip direction under support conditions in two cases:

[0154] First scenario: Under supported conditions, if the anchor bolts or cables only provide anti-slip effect and do not generate an unfavorable component force along the potential sliding direction, then:

[0155]

[0156] In the formula, This represents the total sliding force of the q-th candidate block along the potential sliding direction under support conditions;

[0157] The second case: If each support point on the q-th candidate block has an unfavorable component force along the potential sliding direction, then the unfavorable component forces of all support points should be calculated and summed item by item, and included in the total sliding force under the support conditions. This can be expressed as:

[0158]

[0159] In the formula, This represents the adverse component force generated along the potential sliding direction at the m-th support point on the q-th candidate block; ; This represents the total number of support points on the q-th candidate block. The above summation term represents the accumulation of the adverse force components generated by all support points on the q-th candidate block.

[0160] The stability safety factor of the q-th candidate block under the support condition is:

[0161]

[0162] In the formula, This represents the total anti-slip force of the q-th candidate block along the potential sliding direction under support conditions; This represents the total sliding force of the q-th candidate block along the potential sliding direction under support conditions; It represents the stability safety factor under the support condition of the q-th candidate block.

[0163] S6: Stability safety factor under support conditions Compared with the aforementioned unsupported safety factor threshold Compare; when "Time" indicates the current state. OK, The anchor bolts in the column are set up reasonably, and there is no need to continue adjusting the number of rows and columns of anchor bolts; when If necessary, adjust the number of rows and columns of anchor bolts, and repeat steps S4-S6 until... This achieves the goal of meeting the safety factor requirements.

[0164] S7: Summary Output. Outputs the number of all candidate blocks, the number of rows and columns of support points, and the sliding method information. See results below. Figure 4 .

[0165] Calculation example:

[0166] In a specific engineering application example, this method was applied to the underground powerhouse cavern complex on the right bank of the Kala Hydropower Station. This underground powerhouse cavern complex includes excavated spaces for the main and auxiliary powerhouses, main transformer tunnels, busbar tunnels, water diversion tunnels, and tailrace tunnels, and structural surfaces such as F75, f74, and f258 were simulated. First, a 3D model of the underground cavern complex was created in Rhino based on engineering CAD drawings and geological data, and the main structural surfaces were imported. Then, spatial topology analysis was used to automatically search for possible combinations of closed blocks between the structural surfaces and the cavern excavation faces.

[0167] Calculation results show that a total of 6 blocks were identified in the main and auxiliary plant areas, 4 of which are located in the side walls and 2 in the floor slab. No blocks formed by a combination of deterministic structural surfaces were identified in the main transformer area. Further calculation of the unsupported safety factor for these blocks using the rigid body limit equilibrium method revealed that only 3 blocks met the corresponding control safety factor requirements.

[0168] For candidate blocks identified as hazardous under unsupported conditions according to this method, a local coordinate system can be established on the exposed excavation surface of the block using this method, and an array of anchor bolt or cable support points can be generated based on the preset number of rows, columns, and spacing. For example, in the surrounding rock support optimization analysis of the same project, the Class V surrounding rock tunnel section affected by fault F152 adopted the support measure of immediately applying 32 mm diameter anchor bolts after excavation; after support optimization, the maximum local deformation of the crown arch decreased from approximately 195 mm to approximately 133 mm, a reduction of approximately 31.8%, indicating that anchor bolt support can effectively improve the stability of the surrounding rock of the underground cavern. The above engineering applications show that this method can complete the automatic identification of candidate blocks, the evaluation of unsupported stability, and the auxiliary design of support parameters in real hydropower station underground cavern projects, providing a basis for the identification of hazardous blocks and the determination of reinforcement schemes.

[0169] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for automatic search and stability assessment of critical hazardous blocks in hydraulic tunnels, characterized in that, Includes the following steps: S1: Construct a 3D model of the hydraulic tunnel and automatically identify all blocks based on a spatial topology analysis algorithm; S2: The stability safety factor of the block under unsupported conditions is calculated using the rigid body limit equilibrium method; S3: When the unsupported safety factor of the qth candidate block is less than the set unsupported safety factor threshold, the block is regarded as a dangerous block under unsupported conditions; S4: When the block is a dangerous block, its exposed excavation face shall be supported; S5: Calculate the stability safety factor of the q-th candidate block under the support conditions; S6: Compare the stability safety factor of the qth candidate block with the unsupported safety factor threshold in step S3. When the stability safety factor of the qth candidate block is less than the unsupported safety factor threshold, change the number of rows and columns of the support points in S4, and repeat S4-S6 until the stability safety factor of the qth candidate block is greater than or equal to the unsupported safety factor threshold. S7: Summary output; outputs the number of all candidate blocks, the number of rows and columns of support points, and the sliding method information.

2. The method for automatic search and stability assessment of critical hazardous blocks in hydraulic tunnels according to claim 1, characterized in that, In step S2, the number of sliding surfaces of each candidate block is determined by traversing each candidate block; including: single sliding surface, two sliding surface, and those that do not have the kinematic conditions to slide out towards the open space of the cavern.

3. The method for automatic search and stability assessment of critical hazardous blocks in hydraulic tunnels according to claim 2, characterized in that, When the block is a single-slip surface block, the unsupported safety factor is calculated in two cases. First case: Unsupported safety factor under basic combined working conditions for a single sliding block; ； In the formula, This represents the unsupported safety factor of the qth candidate block under the basic combined working condition when the block is a single-slip surface block. The internal friction angle of the rock surface represents the slip surface; This represents the cohesion of the rock mass at the slip surface; This represents the component of the force exerted by groundwater on the normal direction of the slip surface; This represents the component of the force exerted by groundwater along the sliding direction; This represents the weight of the q-th candidate block; Represents the area of ​​the smooth surface; Indicates the angle of inclination of the slip surface; The second scenario: for single-slip surface blocks, the unsupported safety factor is considered in the case of accidental combinations of working conditions such as seismic action; ； In the formula, This represents the unsupported safety factor of the qth candidate block under accidental combination conditions when the block is a single-slip surface block. Indicates the horizontal acceleration due to seismic action; Represents gravitational acceleration; Indicates the angle of inclination of the slip surface; This represents the cohesion of the rock mass at the slip surface; This represents the weight of the q-th candidate block; This represents the component of the force exerted by groundwater on the normal direction of the slip surface; This represents the component of the force exerted by groundwater along the sliding direction; The internal friction angle of the rock surface represents the slip surface; This represents the area of ​​the smooth surface.

4. The method for automatic search and stability assessment of critical hazardous blocks in hydraulic tunnels according to claim 2, characterized in that, When the block is a two-slip surface block, the unsupported safety factor is calculated in two cases. First case: When there are two sliding blocks, the unsupported safety factor under the basic combined working condition; First, calculate the normal forces on the two sliding surfaces: ； ； In the formula, This represents the normal force of the q-th candidate block on the sliding surface i; This represents the normal force of the q-th candidate block on the sliding surface j; Indicates the angle between the sliding surface i and the vertical auxiliary surface; This represents the angle between the sliding surface j and the vertical auxiliary surface; This represents the angle between sliding surface i and sliding surface j; and Let i and j represent the uplift pressure of groundwater, respectively. Indicates the angle of inclination of the line of intersection between sliding surfaces i and j; This represents the weight of the q-th candidate block; Next, calculate the unsupported safety factor of the double-slip surface block: ； In the formula, When representing a double-slip surface block, it represents the unsupported safety factor of the qth candidate block under the basic combined working condition; Indicates the internal friction angle of the rock surface i; Indicates the internal friction angle of the rock surface j; This represents the cohesive force of the slip surface i; This represents the cohesive force of the slip surface j; and Let i and j represent the areas of the sliding surfaces, respectively. This represents the resultant force of groundwater acting along the intersection of slip surface i and slip surface j; Indicates the angle of inclination of the line of intersection between sliding surfaces i and j; This represents the weight of the q-th candidate block; This represents the normal force of the q-th candidate block on the sliding surface i; This represents the normal force of the q-th candidate block on the sliding surface j; The second scenario: considering the unsupported safety factor for accidental combinations of working conditions such as earthquakes; First, calculate the normal forces on the two sliding surfaces: ； In the formula, This represents the normal force of the q-th candidate block on the sliding surface i; This represents the normal force of the q-th candidate block on the sliding surface j; Indicates the angle between the sliding surface i and the vertical auxiliary surface; This represents the angle between the sliding surface j and the vertical auxiliary surface; This represents the angle between sliding surface i and sliding surface j; and Let i and j represent the uplift pressure of groundwater, respectively. Indicates the angle of inclination of the line of intersection between sliding surfaces i and j; This represents the weight of the q-th candidate block; Indicates the horizontal acceleration due to seismic action; Then calculate the safety factor for the unsupported area: ； In the formula, This represents the unsupported safety factor for a double-sliding wedge-shaped block under accidental combination working conditions. This represents the normal force of the q-th candidate block on the sliding surface i; This represents the normal force of the q-th candidate block on the sliding surface j; The internal friction angle of surface i is represented; This represents the internal friction angle of the slip surface j; This represents the resultant force of groundwater acting along the intersection of slip surface i and slip surface j; and Let i and j represent the cohesion of the sliding surfaces, respectively. and Let i and j represent the areas of the sliding surfaces, respectively.

5. The method for automatic search and stability assessment of critical hazardous blocks in hydraulic tunnels according to claim 1, characterized in that, Step S4 includes the following steps: S4.1: Select three non-collinear points A, B, and C on the exposed excavation face and construct a local coordinate system; S4.2: Using the origin of the local coordinate system As the reference center for the arrangement of the support point array, in and An array of anchor bolts or anchor cables is generated in the local plane of the exposed excavation face of Zhangcheng; assuming that a total of anchor bolts or anchor cables are arranged on the q-th candidate block. OK, The row spacing of the anchor bolts or anchor cables is as follows: The column spacing is ; line number is recorded as The column number is denoted as ,and , For the first line, number The coordinates of the support points of the column in the local coordinate system are: ； In the formula, This represents the three-dimensional coordinates of the support point in the r-th row and b-th column on the q-th candidate block; Then the coordinates of the support point in the r-th row and b-th column of the q-th candidate block in the global coordinate system of the 3D model It can be calculated using the following formula: ； In the formula, These represent the three coordinate components of the support point in the r-th row and b-th column of the q-th candidate block in the global coordinate system of the 3D model, respectively. These are the coordinates of the support point in the local coordinate system; These are the coordinates of the origin of the local coordinate system in the global coordinate system. ; These are the three unit basis vectors of the local coordinate system relative to the global coordinate system. .

6. The method for automatic search and stability assessment of critical hazardous blocks in hydraulic tunnels according to claim 1, characterized in that, Step S5 includes the following steps: S5.1: Calculate the effective component of the force at the m-th support point of the g-th candidate block in the anti-slip direction; ； In the formula, This represents the effective component of the anti-slip force at the m-th support point of the g-th candidate block in the anti-slip direction; This represents the axial support force at the m-th support point; This represents the unit axial direction vector of the m-th support point of the g-th candidate block; Represents the unit vector of the potential sliding direction of the g-th candidate block; S5.2: Calculate the total effective support anti-slip force of the g-th candidate block; ； In the formula, This represents the total effective support and anti-slip force of the g-th candidate block; Indicates the number of anchor bolts used for support; S5.3: Calculate the anti-slip force of the g-th candidate block; The formula is: ； In the formula, This represents the total anti-slip force of the q-th candidate block in the potential sliding direction when unsupported; This represents the anti-slip force of the q-th candidate block; S5.4: Calculate the stability safety factor under the support condition of the g-th candidate block; ； In the formula, This represents the total sliding force under the support condition of the q-th candidate block; It represents the stability safety factor under the support condition of the q-th candidate block.

7. The method for automatic search and stability assessment of critical hazardous blocks in hydraulic tunnels according to claim 6, characterized in that, Step S5 discusses the total sliding force along the potential slip direction under support conditions in two cases: First scenario: Under supported conditions, if the anchor bolts or cables only provide anti-slip effect and do not generate an unfavorable component force along the potential sliding direction, then: ； In the formula, This represents the total sliding force of the q-th candidate block along the potential sliding direction under support conditions; The second scenario: If each support point has an unfavorable component force along the potential sliding direction, then this unfavorable component force is included in the total sliding force under the support conditions; this can be expressed as: ； In the formula, This represents the adverse force generated at the m-th support point along the potential sliding direction; This represents the number of support points on the q-th candidate block.

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