Method for determining the controlling fault and reinforcement area of ​​arch dam site based on numerical simulation

Abstract

The present invention discloses a method for determining the controlling fault and reinforcement area of ​​an arch dam site area based on numerical simulation, comprising the following steps: (1) establishing an arch dam calculation model containing geological faults according to an engineering geological map in combination with a Rhino three-dimensional modeling platform; (2) performing numerical calculations on the arch dam calculation model under different water pressure overload coefficients; (3) calculating the final overload coefficient, and obtaining the deformation displacement value of the arch dam under the final overload coefficient calculation result; (4) determining the controlling fault in the arch dam site area according to the deformation displacement values ​​of the arch dam and the mountain in step (3); (5) determining the reinforcement area of ​​the controlling fault; (6) performing water pressure overload simulation on the arch dam calculation model after the control fault is reinforced. The present invention accurately determines the controlling fault and the control fault reinforcement area in the process of engineering construction, determines the controlling fault of arch dam safety from a quantitative perspective, and reduces human qualitative judgment.

Description

Technical Field

[0001] The invention relates to a method for determining a controlling fault in water conservancy and hydropower engineering construction, geological engineering and numerical simulation calculation, and in particular to a method for determining a controlling fault and a reinforcement area in an arch dam site area based on numerical simulation. Background Art

[0002] As a clean and renewable energy source, hydropower helps to adjust and optimize the energy structure and is of great significance for achieving carbon peak. Arch dams are an indispensable part of hydropower project construction. Through their unique arc design, they efficiently transmit water pressure to the rock foundation and the mountains on both sides, thereby reducing the required materials and reducing costs. This structure provides extremely high stability, enabling arch dams to withstand strong water pressure and earthquakes. At the same time, they also perform well in terms of environmental impact, maintenance requirements and lifespan. They are suitable for the construction of hydropower projects in narrow canyons, optimize space utilization, and are ideal for hydropower generation and water resources management. However, despite the many advantages of arch dams, they still face a series of complex geological problems during the construction process, which are often important factors affecting the progress and safety of the project.

[0003] During the construction of arch dams, geological problems are often an important factor affecting the progress and safety of the project. The complexity of the geological structure places high standards on engineering design. The geological conditions in different regions vary significantly, such as rock type, stratum inclination, and fault distribution. These factors need to be carefully considered in the design stage. Among them, the fault problem has become a key issue in the construction of arch dams. In different hydropower projects, the scale, size, direction, inclination, and inclination of the faults in the dam site area are different. Each fault has a different impact on the safety of the arch dam. If it is judged only based on human experience, it is not possible to accurately judge the controlling faults during the construction and operation and maintenance of the arch dam, which has an important impact on the safety of the arch dam.

[0004] Similarly, in order to ensure the safety and stability of the arch dam, the reinforcement of the control fault is crucial. At present, the traditional method of determining the control fault mainly relies on geological exploration and manual analysis, which is not only time-consuming and labor-intensive, but also easily affected by human factors, resulting in the accuracy and reliability of the results being difficult to guarantee. Due to the complexity and variability of geological conditions, traditional exploration methods often cannot fully and accurately reflect the actual situation when facing complex geological structures. In addition, the existing reinforcement technology is usually based on experience, lacks systematic numerical simulation and scientific basis, and it is difficult to effectively guide the reinforcement measures in actual projects. Such reinforcement measures not only increase the cost of engineering construction due to excessive management, but also reduce construction efficiency. The above problems are common in the current design, construction and numerical analysis of water conservancy and hydropower projects. Therefore, there is an urgent need for a scientific method based on numerical simulation to accurately determine the control faults and their reinforcement areas in the arch dam site area, so as to improve the safety and stability of the arch dam. Summary of the invention

[0005] Purpose of the invention: In order to solve the problem that controlling faults and fault reinforcement areas in hydropower project construction cannot be quantitatively solved through human judgment, the present invention proposes a method for determining controlling faults and reinforcement areas in the arch dam site area based on numerical simulation.

[0006] Technical solution: The method for determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation in the present invention comprises the following steps:

[0007] Step (1) is to establish a calculation model of an arch dam containing geological faults based on the engineering geological map and the Rhino 3D modeling platform. The process is as follows:

[0008] Step (1.1), based on the DEM digital elevation map of the dam site area, establish the ground surface of the arch dam calculation model, i.e., the mountains on both sides, and form a solid by cutting the ground surface downward with the specified elevation plane;

[0009] Step (1.2), according to the fault distribution in the horizontal and cross-sectional images at different positions, the position and scale of the fault are obtained, the fault plane is formed by embedding in the Rhino software, and the fault plane is stretched to a specified thickness on both sides in the normal direction to form a fault entity;

[0010] Step (1.3), establish the arch dam entity and excavation surface according to the construction drawing, the process is: according to the dam body plane section in the construction drawing, carry out lofting and operations from surface to body along the dam end boundary line, carry out embedding operations on the excavation surface to the excavation line, and carry out operations from line to surface;

[0011] Step (1.4), by combining the mountain, excavation surface, and dam body, using the griddle plug-in to perform grid division, and exporting it into an arch dam calculation model containing geological faults;

[0012] Step (2), numerical calculation of the arch dam calculation model under different water pressure overload coefficients λ; the process is:

[0013] Step (2.1), using Flac3D software to perform displacement boundary constraints on the bottom and surrounding of the arch dam calculation model, the process is to apply full constraints to the bottom of the arch dam calculation model and apply normal constraints to the surrounding of the arch dam calculation model;

[0014] Step (2.2), using the elastic constitutive model to perform initial geostress inversion, assigning deformation modulus and Poisson's ratio to each part of the elastic constitutive model, using Flac3D software to perform elastic constitutive equilibrium calculation until equilibrium, and retaining the calculated stress field as the initial geostress field;

[0015] Step (2.3) uses the elastic-plastic constitutive model to apply water pressure to the upper dam surface, calculates the elastic-plastic constitutive model to equilibrium, and obtains the displacement field of the entire arch dam calculation model; the process is:

[0016] Step (2.3.1), assign four parameters, namely deformation modulus E, Poisson's ratio, internal friction angle and cohesion, to the elastic-plastic constitutive model;

[0017] Step (2.3.2), calculate the force of water pressure on the arch dam at the dam bottom elevation under different water pressure overload coefficients:

[0018] P = λ × H × 1000 (1)

[0019] Among them, P is the water pressure at the dam bottom elevation, unit Pa; λ is the water pressure overload coefficient; H is the upstream head, that is, the water depth, unit m;

[0020] Step (2.4), increase the water pressure overload coefficient λ, based on the calculation result of the previous overload coefficient, re-apply the water pressure under the new water pressure coefficient to the upper dam surface, use Flac3D software to calculate the displacement field of the arch dam calculation model under the new overload coefficient, and obtain the deformation displacement value of the dam body on the fault extension plane, the deformation displacement value at the connection between the dam body and the fault, and the deformation displacement value at the connection between the dam body and the mountain under the new overload coefficient from the displacement field of the arch dam calculation model;

[0021] Step (3), according to step (2.4), gradually increase the overload factor until the arch dam calculation model does not converge, that is, the imbalance rate cannot be reduced to 10 -5 , and the final overload factor λ is obtained t and the final overload factor λ t The deformation displacement value of the arch dam under the calculation results;

[0022] Step (4), according to the deformation displacement value of the arch dam and the mountain in step (3), the final overload coefficient λ t The fault with the largest displacement value under the calculation results determines the controlling fault in the arch dam site area;

[0023] Step (5), determine the reinforcement area of ​​the control fault, the process is:

[0024] Step (5.1), define the displacement threshold D as the maximum displacement of the arch dam under normal water level, that is, when the water pressure overload coefficient λ = 1.0;

[0025] Step (5.2), the final overload factor λ t In this case, Flac3D is used to take the area where the displacement of the control fault is greater than the displacement threshold D as the reinforcement area; the process is:

[0026] Step (5.2.1), traverse the arch dam calculation model, determine whether the grid cells in the arch dam calculation model are within the control fault, and extract the grid cell coordinates (x, y, z) that meet the conditions;

[0027] Step (5.2.2), finding the node coordinates close to the grid unit coordinates, and taking the node displacement under the node coordinates as the grid unit displacement;

[0028] Step (5.2.3), extract the node displacement vector (U x ,U y ,U z ), and calculate the resultant displacement

[0029] Step (5.2.4) determines whether the displacement of the grid unit is greater than the displacement threshold. If the displacement of the grid unit is greater than the displacement threshold, the grid unit is used as a reinforcement unit.

[0030] In step (6), the control fault is reinforced based on the initial ground stress, and the final overload coefficient λ obtained before reinforcement is used. t , the water pressure overload simulation was carried out on the calculation model of the arch dam after the control fault reinforcement.

[0031] The engineering geological map in step (1) includes a plan view and a cross-sectional view of the dam site area containing lithology boundaries and fault distribution lines.

[0032] In step (1), the arch dam calculation model includes the arch dam, the dam foundation, the mountains on both sides and the geological faults.

[0033] The ground surface in step (1.1) is the original terrain before the dam foundation is excavated.

[0034] The specified elevation in step (1.1) is 1 to 2 times the dam height downward from the dam foundation.

[0035] The specified thickness in step (1.2) is the fault thickness obtained from geological exploration.

[0036] In step (1.4), the mountain, excavation surface and dam body are combined, and the grid is divided using the griddle plug-in, and then exported as an f3grid file, which is the calculation model of the arch dam containing the geological fault.

[0037] In step (3), the deformation of the dam body located on the fault extension plane, the deformation of the dam body at the connection between the dam body and the fault, and the deformation of the dam body at the connection between the dam body and the mountain are obtained.

[0038] In step (5.2), the final overload factor λ tIn the next step, the IPython Console of Flac3D is used to control the area where the fault displacement is greater than the displacement threshold D as the reinforcement area.

[0039] In step (6), the calculation model of the arch dam after the control fault reinforcement is used to perform water pressure overload calculation using the final overload coefficient obtained before reinforcement, and the deformation of the arch dam under the same overload coefficient before and after reinforcement is compared.

[0040] In step (2), the water pressure overload coefficient λ is the pressure of the upstream water head on the upstream face of the arch dam, which is triangularly distributed. By multiplying the hydraulic gradient on the upper dam face by a water pressure overload coefficient λ, the effect of the upstream water pressure on the arch dam is increased. When the numerical simulation calculation does not converge, the value of the overload coefficient λ is not less than 4.0, and the arch dam is judged to be safe. The increment between different water pressure overload coefficients is 0.1, that is, λ = 1.0, 1.1, 1.2, ...

[0041] In step (3), if the calculation of λ converges under the water pressure overload coefficient and does not converge under the next water pressure overload coefficient calculation, then λ at this time is the final overload coefficient λ t .

[0042] In step (4), the controlling fault is the fault that has the greatest impact on the arch dam among all faults. The controlling fault is manifested as the displacement and deformation range of the part of the arch dam connected to it.

[0043] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0044] (1) The present invention provides a method for determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation. When there are multiple faults in the dam site area, the fault with the most significant impact on the overall safety of the arch dam is obtained as the controlling fault of the dam site area through numerical simulation and analysis based on water pressure overload, that is, the fault with the largest displacement under the final overload coefficient. The controlling fault of the arch dam safety is determined from a quantitative perspective, which reduces human qualitative judgment and makes the result more accurate.

[0045] (2) The method for determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation in the present invention takes the maximum displacement of the arch dam when the normal water storage level, that is, the water pressure coefficient is equal to 1, as the displacement threshold, and takes the part of the controlling fault displacement under the final overload coefficient that is greater than the displacement threshold as the controlling fault reinforcement area, quantitatively determines the controlling fault reinforcement area, accurately controls the fault danger area, improves construction efficiency, and reduces costs.

[0046] (3) This method quickly groups the units with displacements greater than the displacement threshold into reinforcement units, thus improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1A method step diagram of determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation according to the present invention;

[0048] Figure 2 It is a schematic diagram of water pressure overload in the present invention;

[0049] Figure 3 It is the calculation model diagram of the arch dam in the present invention;

[0050] Figure 4 This is a schematic diagram of the spatial relationship between the fault layer and the arch dam of the present invention;

[0051] Figure 5 is the final overload coefficient λ before reinforcement in the present invention t =5.0 Arch dam deformation diagram (deformation effect magnified 10 times);

[0052] Figure 6 The displacement cloud diagram of the arch dam when the overload coefficient λ=1.0 before reinforcement in the present invention;

[0053] Figure 7 is the final overload coefficient λ before reinforcement in the present invention t =5.0 when the fault displacement map and fault reinforcement area map are controlled;

[0054] Figure 8 This is the deformation diagram of the arch dam when the overload coefficient λ=5.0 after reinforcement in the present invention (the deformation effect is magnified 10 times). DETAILED DESCRIPTION

[0055] like Figures 1 to 8 As shown, the method for determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation of the present invention comprises the following steps:

[0056] Step (1), based on the engineering geological map, in combination with the Rhino three-dimensional modeling platform, a calculation model of an arch dam containing geological faults is established; wherein the engineering geological map includes a plan view and a cross-sectional view of the dam site area containing rock lithology boundaries and fault distribution lines.

[0057] Step (2), performing numerical calculations on the arch dam calculation model under different water pressure overload coefficients λ;

[0058] Step (3), calculate the final overload factor λ t ; Get the final overload factor λ t The deformation displacement value of the arch dam under the calculation result, the deformation in this embodiment refers to the deformation of the dam body located on the fault extension plane, the connection between the dam body and the fault, and the connection between the dam body and the mountain.

[0059] Step (4), according to the deformation displacement value of the arch dam and the mountain in step (3), the final overload coefficient λ tThe fault with the largest displacement value under the calculation results determines the controlling fault in the arch dam site area;

[0060] Step (5), determining the reinforcement area of ​​the control fault;

[0061] Step (6), based on the initial ground stress, the control fault is reinforced, using the final overload coefficient λ obtained before reinforcement t , the water pressure overload simulation was carried out on the calculation model of the arch dam after the control fault reinforcement.

[0062] In step (1), the arch dam calculation model includes the arch dam, the dam foundation, the mountains on both sides and the geological faults. The process of establishing the arch dam calculation model is as follows:

[0063] Step (1.1), based on the DEM digital elevation map of the dam site, establish the ground surface of the arch dam calculation model, that is, the mountains on both sides. The ground surface is cut with the specified elevation plane by downward projection to form a solid. The ground surface here is the original terrain before the dam foundation is excavated, and the specified elevation is 1 to 2 times the dam height below the bottom of the dam foundation.

[0064] Step (1.2), the location and scale of the fault are obtained according to the fault distribution in the horizontal and cross-sectional diagrams at different positions, and the fault plane is formed by the embedding operation in the Rhino software. The fault plane is stretched to a specified thickness on both sides in the normal direction to form a fault entity; the specified thickness here is the corresponding fault thickness obtained from geological exploration.

[0065] Step (1.3) is to establish the arch dam entity and excavation surface according to the engineering construction drawing. The process is as follows: according to the dam body plane section in the construction drawing, the layout and the operation from surface to body are carried out along the dam end boundary line, and the excavation line is embedded on the excavation surface, and the operation from line to surface is carried out.

[0066] Step (1.4), by combining the mountain, excavation surface and dam body, using the griddle plug-in to perform grid division, and exporting it as an f3grid file, that is, the arch dam calculation model containing the geological fault.

[0067] The calculation model of arch dam with geological faults is established as follows Figure 3 As shown in the figure, DAM represents the dam, Fault1 and Fault2 represent faults, and MOUNTAIN represents the dam foundation and the mountains on both sides.

[0068] Figure 4 The figure in the middle shows the spatial relationship between the fault and the arch dam and the fault characteristics. From the top view, it can be seen that the extension length of Fault1 is 1.5 times that of Fault2. From the view from upstream to downstream, the thickness of Fault1 is twice that of Fault2. The two faults are of similar depth and have similar elevations where they connect with the arch dam. Fault1 is a counter-dipping fault for the arch dam, while Fault2 is a forward-dipping fault for the arch dam.

[0069] Combined with the calculation parameters in Table 1, the geometric characteristics, mechanical characteristics of the two faults and the positional relationship with the arch dam fully reflect the advantages of the present invention. From the fault scale analysis, the scale of Fault1 fault is larger than that of Fault2 fault, and the fault belongs to the dangerous area. From the perspective of human qualitative analysis, the larger the dangerous area, the more dangerous it is. From the calculation parameters in Table 1, it can be concluded that the mechanical parameters of Fault1 fault are weaker than those of Fault2 fault, and Fault1 fault is more likely to be destroyed first. Combined with the above qualitative analysis, Fault1 is used as the controlling fault of the dam site area.

[0070] Table 1 Calculation parameters

[0071]

[0072] In step (2), the numerical calculation process of the arch dam calculation model under different water pressure overload coefficients λ is as follows:

[0073] Step (2.1), use Flac3D software to perform displacement boundary constraints on the bottom and surrounding of the arch dam calculation model, wherein full constraints are applied to the bottom of the arch dam calculation model, and normal constraints are applied to the surrounding of the arch dam calculation model.

[0074] In step (2.2), the elastic constitutive model is used to perform initial geostress inversion. The deformation modulus E and Poisson's ratio in Table 1 are assigned to each part of the elastic constitutive model. The elastic constitutive equilibrium calculation is performed using Flac3D software until the imbalance ratio is less than 10. -5 , that is, equilibrium, and the stress field obtained by calculation is retained as the initial geostress field.

[0075] Step (2.3), using the elastic-plastic constitutive model, apply water pressure to the upper dam surface, and calculate the elastic-plastic constitutive model until the imbalance rate is less than 10 -5 , that is, equilibrium, and the displacement field of the arch dam calculation model is obtained. The process is:

[0076] Step (2.3.1), based on the initial geostress field calculated by the elastic constitutive model, Figure 3 The elastic-plastic constitutive model is adopted, and four parameters are given: deformation modulus E, Poisson's ratio, internal friction angle, and cohesion (Table 1).

[0077] Step (2.3.2) is to calculate the overload coefficient by applying different water pressures. The water pressure is applied by applying triangular distributed water pressure on the upper surface of the arch dam in combination with the water level elevation, such as Figure 2 As shown in the figure, the effect of water pressure at the water surface elevation on the arch dam is constant at 0Pa. The effect of water pressure at the dam bottom elevation on the arch dam under different water pressure overload coefficients is calculated by formula (1).

[0078] P = λ × H × 1000 (1)

[0079] Where: P is the water pressure at the dam bottom elevation, unit (Pa); λ is the water pressure overload coefficient; H is the upstream head, that is, the water depth, unit (m).

[0080] like Figure 2 As shown in Figure 1, when the arch dam height is 235m, the upstream water head H is 230m, and the overload coefficient λ is 1.0, the force of the dam bottom elevation water pressure on the arch dam is calculated by formula (1) as P = 230000Pa. Therefore, according to the dam bottom elevation water pressure of 230000Pa and the dam top elevation water pressure of 0Pa, a triangular uniformly distributed water pressure is applied to the upstream surface of the arch dam.

[0081] Step (2.4), gradually increase the water pressure overload coefficient λ, based on the calculation result of the previous overload coefficient, reapply the water pressure under the new water pressure coefficient to the upper dam surface, use Flac3D software to calculate the displacement field of the arch dam calculation model under the new overload coefficient, and obtain the deformation displacement value of the dam body on the fault extension plane, the deformation displacement value at the connection between the dam body and the fault, and the deformation displacement value at the connection between the dam body and the mountain under the new overload coefficient from the displacement field of the arch dam calculation model. The increment between the water pressure overload coefficients is 0.1, that is, λ=1.0,1.1,1.2,…

[0082] In step (3), the final overload coefficient λ is calculated to converge under a certain water pressure overload coefficient, and does not converge under the next water pressure overload coefficient. In this embodiment, the method in step (2.4) is used. The calculation converges when the overload coefficient λ before reinforcement is 5.0, and does not converge when λ is 5.1, so the final overload coefficient λ t =5.0.

[0083] according to Figure 5 The deformation of the arch dam at this time was obtained: the left side of the arch dam was affected by fault Fault2, and deformation creases appeared along the extension surface of Fault2; rock arching occurred at the connection between the dam body and faults Fault1 and Fault2, and the shoulder part and the arch dam were displaced; a large-scale mountain arching occurred at the connection between the dam body and the mountain, and the affected area on the left bank was larger than that on the right bank.

[0084] In step (4), the controlling fault is the one that has the greatest impact on the arch dam among all the faults. The specific impact is the displacement and deformation range of the part connected to the arch dam. According to the deformation of the arch dam and the mountain described in step (3), Fault 2 has a greater impact on the arch dam and the mountain than Fault 1, so Fault 2 is determined to be the controlling fault.

[0085] In step (5), the reinforcement area of ​​the control fault is determined according to the following method:

[0086] Step (5.1), define the displacement threshold D as the maximum displacement of the arch dam under normal water level, that is, when the water pressure overload coefficient λ = 1.0.

[0087] Step (5.2), the final overload factor λ t In this case, the IPython Console interface of Flac3D is used to control the area where the fault displacement is greater than the displacement threshold D as the reinforcement area through commands.

[0088] The steps of step (5.2) are as follows:

[0089] Step (5.2.1), traverse the entire arch dam calculation model, determine whether the grid cells in the arch dam calculation model are within the control fault, and extract the grid cell coordinates (x, y, z) that meet the conditions;

[0090] Step (5.2.2), find the node coordinates closest to the grid unit coordinates, obtain the node displacement under the node coordinates, and use the node displacement as the grid unit displacement;

[0091] Step (5.2.3), extract the node displacement vector (U x ,U y ,U z ), and calculate the resultant displacement

[0092] Step (5.2.4) determines whether the displacement of the grid unit is greater than the displacement threshold. If the displacement of the grid unit is greater than the displacement threshold, the grid unit is used as a reinforcement unit.

[0093] like Figure 6 As shown in the figure, the maximum displacement of the arch dam is 0.101m when the overload coefficient λ before reinforcement is 1.0, so the displacement threshold D is determined to be 0.101m. Extract the final overload coefficient λ before reinforcement t Control the coordinates (x, y, z) of the grid cells whose fault displacement is greater than D, and use these grid cells as reinforcement areas, such as Figure 7 shown.

[0094] In step (6), the control fault is reinforced based on the initial ground stress, and the final overload coefficient λ obtained before reinforcement is used. t , the water pressure overload simulation was carried out on the calculation model of the arch dam after the control fault reinforcement.

[0095] In this embodiment, the final overload coefficient λ obtained before reinforcement t The reinforced model was used to simulate the water pressure overload with an overload factor of 5.0, and the deformation of the arch dam under the same overload factor before and after reinforcement was compared.

[0096] like Figure 8 As shown in Figure 2, the deformation diagram of the arch dam when the overload coefficient λ = 5.0 after reinforcement (the deformation effect is magnified 10 times), and Figure 5 By comparison, after the reinforcement of fault Fault2, the deformation of the connection between the arch dam and Fault2 and the left bank mountain was improved, and due to the influence of deformation coordination, the deformation of the connection between Fault1 and the arch dam on the right bank and the right bank mountain was also improved.

[0097] from Figure 4 It can be seen that the fault Fault1 is larger than the fault Fault2 in scale. From the analysis in Table 1, it can be seen that the mechanical properties of the fault Fault1 are worse than those of the fault Fault2. Therefore, according to human experience, Fault1 is regarded as a control fault and is strengthened emphatically. This is because the correlation between the topography of the dam site and the strike and dip of the fault is ignored. The method of the present invention comprehensively considers the correlation between the topography of the dam site and the strike and dip of the fault, and analyzes the control fault of the dam site from a quantitative and objective perspective, which provides a guarantee for engineering construction and safe operation of the dam.

Claims

1. A method for determining the controlling fault and reinforcement area of ​​an arch dam site based on numerical simulation, characterized in that: The following steps are involved: Step (1), according to the engineering geological map, combined with the Rhino three-dimensional modeling platform, establish an arch dam calculation model containing geological faults; Step (2), numerical calculation of the arch dam calculation model under different water pressure overload coefficients λ; the process is as follows: Step (2.1), using Flac3D software to perform displacement boundary constraints on the bottom and surrounding of the arch dam calculation model, the process is to apply full constraints to the bottom of the arch dam calculation model and apply normal constraints to the surrounding of the arch dam calculation model; Step (2.2), using the elastic constitutive model to perform initial geostress inversion, assigning deformation modulus and Poisson's ratio to each part of the elastic constitutive model, using Flac3D software to perform elastic constitutive equilibrium calculation, and retaining the calculated stress field as the initial geostress field; Step (2.3), using the elastic-plastic constitutive model, applying water pressure to the upper dam surface, calculating the elastic-plastic constitutive model, and obtaining the displacement field of the arch dam calculation model; Step (2.4), increase the water pressure overload coefficient λ, based on the calculation result of the previous overload coefficient, re-apply the water pressure under the new water pressure coefficient to the upper dam surface, use Flac3D software to calculate the displacement field of the arch dam calculation model under the new overload coefficient, and obtain the deformation displacement value of the dam body on the fault extension plane, the deformation displacement value at the connection between the dam body and the fault, and the deformation displacement value at the connection between the dam body and the mountain under the new overload coefficient from the displacement field of the arch dam calculation model; Step (3), according to step (2.4), by increasing the overload factor until the arch dam calculation model does not converge, the final overload factor λ is obtained t , and the final overload factor λ is obtained t The deformation displacement value of the arch dam under the calculation results; Step (4), according to the deformation displacement values ​​of the arch dam and the mountain in step (3), the controlling fault in the arch dam site area is determined by the fault with the largest displacement value under the final overload coefficient calculation result; Step (5), determine the reinforcement area of ​​the control fault, the process is: Step (5.1), define the displacement threshold D as the maximum displacement of the arch dam under normal water level, that is, when the water pressure overload coefficient λ = 1.0; Step (5.2), at the final overload factor λ t In this case, Flac3D is used to take the area where the displacement of the control fault is greater than the displacement threshold D as the reinforcement area; the process is: Step (5.2.1), traverse the arch dam calculation model, determine whether the grid cells in the arch dam calculation model are within the control fault, and extract the grid cell coordinates (x, y, z) that meet the conditions; Step (5.2.2), finding the node coordinates close to the grid unit coordinates, and taking the node displacement under the node coordinates as the grid unit displacement; Step (5.2.3), extract the node displacement vector (U x ,U y ,U z ), and calculate the total displacement D m , Step (5.2.4), determine whether the displacement of the grid unit is greater than the displacement threshold, if the displacement of the grid unit is greater than the displacement threshold, the grid unit is used as a reinforcement unit; Step (6), based on the initial ground stress, the control fault is reinforced, using the final overload coefficient λ obtained before reinforcement t , the water pressure overload simulation was carried out on the calculation model of the arch dam after the control fault reinforcement.

2. The method for determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation according to claim 1 is characterized in that: The engineering geological map includes a plan view and a cross-sectional view of the dam site area containing rock stratum lithology boundaries and fault distribution lines.

3. The method for determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation according to claim 1 is characterized in that: In step (1), the arch dam calculation model includes the arch dam, the dam foundation, the mountains on both sides and the geological faults; the process of step (1) is: Step (1.1), based on the DEM digital elevation map of the dam site area, establish the ground surface of the arch dam calculation model, and form a solid by cutting the ground surface downward with the specified elevation plane; Step (1.2), according to the fault distribution in the horizontal and cross-sectional images at different positions, the position and scale of the fault are obtained, the fault plane is formed by embedding in the Rhino software, and the fault plane is stretched to a specified thickness on both sides in the normal direction to form a fault entity; Step (1.3), establish the arch dam entity and excavation surface according to the construction drawing, the process is: according to the dam body plane section in the construction drawing, set out along the dam end boundary line, perform face embedding operation on the excavation surface to perform the operation from line to surface; Step (1.4) combines the mountain, excavation surface, and dam body, and uses the griddle plug-in to perform grid division to derive the calculation model of the arch dam containing geological faults.

4. The method for determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation according to claim 3 is characterized in that: In step (1.1), the ground surface is the original terrain before the dam foundation is excavated; the specified elevation is 1 to 2 times the dam height downward from the bottom of the dam foundation.

5. The method for determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation according to claim 1 is characterized in that: The process of step (2.3) is: Step (2.3.1), assign four parameters, namely deformation modulus E, Poisson's ratio, internal friction angle and cohesion, to the elastic-plastic constitutive model; Step (2.3.2), calculate the force of water pressure on the arch dam at the dam bottom elevation under different water pressure overload coefficients: P = λ × H × 1000 (1) Among them, P is the water pressure at the dam bottom elevation, unit is Pa; λ is the water pressure overload coefficient; H is the upstream head, that is, the water depth, unit is m.

6. The method for determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation according to claim 3 is characterized in that: In step (1.2), the specified thickness is the fault thickness obtained from geological exploration.

7. The method for determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation according to claim 3 is characterized by: In step (1.4), the mountain, excavation surface and dam body are combined, and the griddle plug-in is used to divide the grid and export it into an f3grid file containing the arch dam calculation model of the geological fault.

8. The method for determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation according to claim 1, characterized in that: In step (3), the deformation of the dam body located on the fault extension plane, the deformation of the dam body at the connection between the dam body and the fault, and the deformation of the dam body at the connection between the dam body and the mountain are obtained.

9. The method for determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation according to claim 1, characterized in that: In step (5.2), the final overload factor λ t In the next step, the IPython Console of Flac3D is used to control the area where the fault displacement is greater than the displacement threshold D as the reinforcement area.

10. The method for determining the controlling fault and reinforcement area of ​​the arch dam site area based on numerical simulation according to claim 1, characterized in that: In step (6), the control fault is reinforced, and the final overload coefficient obtained before reinforcement is used to perform a water pressure overload simulation on the arch dam calculation model after the control fault reinforcement, and the deformation displacement values ​​of the arch dam under the same overload coefficient before and after reinforcement are compared.

Images