Deep anti-sliding stability assessment method for gravity dam formed by complex slip crack surface in strong earthquake region

Abstract

The invention discloses a deep anti-sliding stability evaluation method for a gravity dam formed by complex slip crack surfaces in a strong earthquake region. The method comprises the steps that S1, a dam-foundation system finite element analysis model of a deep sliding block body formed by weak structural surfaces in foundation rock mass is constructed; s2, based on the constructed model, dividing the dam-deep sliding block body into strip blocks in the vertical direction, wherein the number of the strip blocks is equal to that of structural surfaces of the deep sliding block body; s3, extracting the dynamic internal force of the sliding surface on each block at each time step, respectively taking the dynamic internal force and the static load acting on each block as external force, gradually solving the action ratio coefficient of the deep anti-sliding stability resistance of the gravity dam at each time step, and drawing a time history curve of the action ratio coefficient of the deep anti-sliding stability; and S4, evaluating the deep anti-sliding stability of the gravity dam according to the minimum deep anti-sliding stability action ratio coefficient in the time history curve. According to the method, comprehensive and comprehensive evaluation can be carried out on deep-layer anti-sliding stability and anti-seismic safety of the gravity dam in the strong earthquake region, so that long-term safe operation of the dam is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of gravity dam anti-sliding stability analysis, and in particular relates to a method for evaluating the deep anti-sliding stability of a gravity dam formed by complex sliding surfaces in a strong earthquake zone. Background Art

[0002] During dam design, due to the inevitable presence of weak interlayers and gently dipping cracks in the dam foundation rock mass, gravity dams may experience deep sliding failure along the weak structural surfaces within the dam foundation rock mass under strong earthquakes, leading to deep sliding instability of the dam. Existing static and dynamic safety assessments of the deep anti-sliding stability of gravity dams are primarily based on the response spectrum method for massless foundations. However, the anti-sliding stability of dams under seismic loads differs significantly from that under static loads. In fact, seismic loads exhibit significant cyclical variations, which result in deep sliding instability of the dam as a gradual accumulation of residual deformation. The fact that the instantaneous deep anti-sliding stability evaluation index obtained through dynamic analysis based on the response spectrum method for massless foundations exceeds the allowable value does not necessarily indicate that the dam will ultimately suffer deep sliding instability.

[0003] Therefore, the key issue in the evaluation of deep anti-sliding stability and seismic safety of gravity dams lies in proposing corresponding deep anti-sliding stability evaluation indicators and evaluation criteria for different calculation and analysis methods and models, forming a complete evaluation system of "method-model-evaluation" that matches each other, and presenting a progressive process from shallow to deep and from simple to complex in the analysis methods and models. The evaluation indicators and evaluation criteria gradually change from conservative to close to engineering reality according to the progressive changes of methods and models. Summary of the Invention

[0004] In response to the above-mentioned deficiencies in the prior art, the present invention provides a method for evaluating the deep anti-sliding stability of gravity dams composed of complex sliding surfaces in strong earthquake zones, which solves the problem that the existing evaluation indicators and criteria obtained based on the massless foundation response spectrum method are difficult to accurately reflect the deep anti-sliding stability of gravity dams.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a method for evaluating the deep anti-sliding stability of a gravity dam composed of complex sliding surfaces in a strong earthquake zone, comprising the following steps: S1. Construct a finite element analysis model of the dam-foundation system with a deep sliding block consisting of weak structural surfaces within the foundation rock mass; S2. Based on the constructed finite element analysis model of the dam-foundation system, the dam-deep sliding block is divided vertically into strips equal to the number of deep sliding block structural surfaces at each boundary of the deep sliding block structural surface; S3. Extract the dynamic internal force of the sliding surface of each block at each time step, and use it together with the static load acting on each block as the external force. Calculate the deep anti-sliding stability resistance ratio coefficient of the gravity dam step by step at each time step, and draw a time history curve of the deep anti-sliding stability ratio coefficient. S4. Evaluate the deep anti-sliding stability of the gravity dam based on the minimum deep anti-sliding stability ratio coefficient in the time history curve.

[0006] Furthermore, in step S3, the method for solving the gravity dam deep anti-sliding stability resistance ratio coefficient is specifically as follows: S31. Based on the resistance function and action effect function of strip i at time step j, a calculation formula for the deep anti-sliding stability resistance action ratio coefficient of the entire gravity dam foundation at each time step is constructed; S32. Based on the fact that the deep anti-sliding stability resistance ratio coefficients of all blocks are equal, the calculation formula for the deep anti-sliding stability resistance ratio coefficient is simplified; S33. Based on the calculation formula of the deep anti-sliding stability resistance coefficient of each block, N-1 equations about the sum of the shear forces on both sides of the strip i are constructed at each time step j, and combined with the balance formula of the internal force of the deep anti-sliding system of the gravity dam foundation, the solution is obtained for each time step. The sum of the shear forces between the lateral contact surfaces of each strip ; S34, will Substitute the calculation formula of the deep anti-sliding stability resistance ratio coefficient into the solution to obtain the deep anti-sliding stability resistance ratio coefficient of the gravity dam at each time step j.

[0007] Furthermore, in step S31, the deep anti-slip stability resistance ratio coefficient The calculation formula is: Where, represents the deep anti-sliding stability resistance coefficient of block i at time step j, represents the resistance function of block i at time step j, represents the effect function of block i at time step j, Indicates the standard value of material performance, Indicates the material performance partial coefficient, represents the standard value of geometric parameters, represents the structural importance coefficient, represents the ultimate limit state structural coefficient of deep anti-sliding stability bearing capacity, represents the design condition coefficient, represents the permanent action partial coefficient, Indicates the permanent effect standard value, represents the variable action partial coefficient, Indicates the standard value of variable action.

[0008] Furthermore, in step S32, the simplified deep anti-sliding stability resistance ratio coefficient The calculation formula is: Where, , ,…, Respectively represent the resistance function of blocks i~N at time step j, , ,…, Represents the effect function of blocks i~N at time step j.

[0009] Furthermore, in step S4, when the minimum deep anti-slip stability coefficient When , the gravity dam is in the deep sliding stability range and has deep anti-sliding stability; When the minimum deep anti-sliding stability ratio coefficient According to the cumulative duration of the deep anti-sliding stability coefficient of each time step , analyze the deep anti-sliding stability of gravity dams.

[0010] Furthermore, in step S4, when Cumulative duration When the gravity dam is outside the deep sliding stability range, the nonlinear contact between the dam body, deep sliding block and foundation is considered, and the deep anti-sliding stability of the medium gravity dam is further evaluated through nonlinear time history response analysis; When it appears Cumulative duration and total duration The proportion of Less than When , the gravity dam is in the deep sliding stability range and has deep anti-sliding stability; When it appears Cumulative duration and total duration The proportion of Greater than When the gravity dam is outside the deep sliding stability range, the nonlinear contact between the dam body, deep sliding block and foundation is considered, and the deep anti-sliding stability of the medium gravity dam is further evaluated through nonlinear time history response analysis; in, and All are set constants less than 1.

[0011] Furthermore, the method for further evaluating the deep anti-sliding stability of medium gravity dams is as follows: For the finite element analysis model of the dam-foundation system, a contact model is used to consider the nonlinearity between the dam body, deep sliding block and foundation, and a nonlinear dynamic time-history response analysis is performed taking into account the radiation damping foundation effect; According to the results of nonlinear dynamic time-history response analysis, the sum of the sliding areas of each sliding surface of the deep sliding block is calculated. Total sliding surface area Proportion ; judge Is it established? To set the threshold; If so, the gravity dam is within the deep sliding stability range and has deep anti-sliding stability; If not, the gravity dam is at risk of deep anti-sliding instability failure and needs to be strengthened.

[0012] Furthermore, the total sliding surface area The calculation formula is: The sum of the sliding areas of the sliding surfaces of the deep sliding block The calculation formula is: Where, Indicates the influence area of ​​each contact point on the contact surface, is the area affected by the contact point where sliding failure occurs on the contact surface, is the total number of contact points.

[0013] The beneficial effects of the present invention are: The present invention proposes a deep anti-sliding stability evaluation method based on the elastic dynamic time history of the massless foundation line and its corresponding evaluation criteria, which can solve the problem that the dynamic analysis method based on the massless foundation response spectrum method cannot reflect the significant reciprocating variation characteristics of the seismic load, and that the instantaneous deep anti-sliding stability evaluation index obtained thereby exceeds the allowable value and does not necessarily indicate the ultimate deep sliding instability and destruction of the dam.

[0014] Based on the conclusions obtained from the elastic time-history method of the massless foundation line, the present invention adopts a contact model to consider the contact nonlinearity between the dam body, the deep sliding block and the foundation for the gravity dam-foundation system, and conducts a nonlinear dynamic time-history response study taking into account the radiation damping foundation effect. The evaluation index of the deep anti-sliding instability and destruction of the gravity dam and the corresponding evaluation criteria are proposed, which can realize a comprehensive and comprehensive evaluation of the deep anti-sliding stability and seismic safety of the gravity dam in the strong earthquake zone, so as to ensure the long-term safe operation of the dam.

[0015] The present invention addresses the key issues of deep anti-sliding stability and seismic safety evaluation of gravity dams, and proposes corresponding deep anti-sliding stability evaluation indicators and evaluation criteria based on different calculation and analysis methods and models, forming a complete evaluation system of "method-model-evaluation" that complements each other. The analysis methods and models present a progressive process from shallow to deep and from simple to complex, and the evaluation indicators and evaluation criteria gradually change from being conservative to being close to engineering reality according to the progressive changes of methods and models. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a flow chart of the deep anti-sliding stability assessment method for a gravity dam with complex sliding surfaces in a strong earthquake zone provided by the present invention.

[0017] Figure 2 Schematic diagram of the division of deep anti-sliding stability strips of the gravity dam provided by the present invention (a) and the calculation method (b).

[0018] Figure 3 Schematic diagram of the deep anti-sliding stability evaluation criteria for gravity dams provided by the present invention. DETAILED DESCRIPTION

[0019] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0020] Based on the need for deep anti-sliding stability and seismic safety evaluation of gravity dams under strong earthquake forces and the defects of existing evaluation indicators and criteria based on the response spectrum of massless foundations, the present invention proposes a deep anti-sliding stability evaluation method for gravity dams with complex sliding surfaces in strong earthquake areas, so as to achieve a comprehensive and comprehensive evaluation of the deep anti-sliding stability and seismic safety of gravity dams in strong earthquake areas, thereby ensuring the long-term safe operation of the dam.

[0021] The method for evaluating the deep anti-sliding stability of a gravity dam formed by complex sliding surfaces in a strong earthquake zone in the embodiment of the present invention is as follows: Figure 1 As shown, the following steps are included: S1. Construct a finite element analysis model of the dam-foundation system with a deep sliding block consisting of weak structural surfaces within the foundation rock mass; S2. Based on the constructed finite element analysis model of the dam-foundation system, the dam-deep sliding block is divided vertically into strips equal to the number of deep sliding block structural surfaces at each boundary of the deep sliding block structural surface; S3. Extract the dynamic internal force of the sliding surface of each block at each time step, and use it together with the static load acting on each block as the external force. Calculate the deep anti-sliding stability resistance ratio coefficient of the gravity dam step by step at each time step, and draw a time history curve of the deep anti-sliding stability ratio coefficient. S4. Evaluate the deep anti-sliding stability of the gravity dam based on the minimum deep anti-sliding stability ratio coefficient in the time history curve.

[0022] In step S1 of the embodiment of the present invention, based on the topographic characteristics of the dam site and the physical properties of the bedrock in the study area, a finite element analysis model of the dam-foundation system consisting of a deep sliding block composed of weak structural surfaces inside the foundation rock mass is constructed, and a study on the elastic dynamic time-history response of the massless foundation line is carried out.

[0023] In step S2 of the embodiment of the present invention, as Figure 2 As shown, at each boundary of the structural surface of the deep sliding block, the dam-deep sliding block is divided vertically into strips equal to the number of structural surfaces.

[0024] In step S3 of the embodiment of the present invention, according to the strip-block division result, the dynamic internal force of the sliding surface of each strip block at each time step is extracted and used together with the static load acting on each strip block as the external force. Step-by-step solution of the ratio coefficient of deep anti-sliding stability resistance of gravity dams , and then give Time history curve, is the total number of time steps.

[0025] In step S3 of this embodiment, the process of solving the ratio coefficient of the deep anti-sliding stability resistance of the gravity dam is based on the gravity dam design specifications and takes into account the seismic load. Therefore, the relevant coefficients are all taken according to the gravity dam design specifications. Specifically, the solution process is as follows: S31. Based on the resistance function and action effect function of strip i at time step j, a calculation formula for the deep anti-sliding stability resistance action ratio coefficient of the entire gravity dam foundation at each time step is constructed; S32. Based on the fact that the deep anti-sliding stability resistance ratio coefficients of all blocks are equal, the calculation formula for the deep anti-sliding stability resistance ratio coefficient is simplified; S33. Based on the calculation formula of the deep anti-sliding stability resistance coefficient of each block, N-1 equations about the sum of the shear forces on both sides of the strip i are constructed at each time step j, and combined with the balance formula of the internal force of the deep anti-sliding system of the gravity dam foundation, the solution is obtained for each time step. The sum of the shear forces between the lateral contact surfaces of each strip ; S34, will Substitute the calculation formula of the deep anti-sliding stability resistance ratio coefficient into the solution to obtain the deep anti-sliding stability resistance ratio coefficient of the gravity dam at each time step j.

[0026] In step S31 of this embodiment, the resistance function of block i at time step j is and action-effect function They are: Where, Represents a bar The shear friction coefficient of the deep sliding block structure surface, Represents a bar The deadweight of the deep sliding block, Represents a bar The deep sliding block is covered by the deadweight of the dam body. Represents a bar The inclination angle of the deep sliding block structure surface, express Time step bar The sum of the shear forces on both sides is positive if it points upstream. Indicates known Time Step Angle with the horizontal direction, Represents a bar Water pressure on the surface of deep sliding block structure, Represents a bar Resultant lateral water pressure, Represents a bar Subject to other horizontal static loads, express Time step bar Horizontal earthquake load on the surface of deep sliding block structure, express Time step bar Vertical earthquake load on the surface of deep sliding block structure, Represents a bar Shear cohesion of deep sliding block structure surface, Represents a bar The structural surface area of ​​deep sliding blocks.

[0027] Each time step Ratio coefficient of resistance action of each strip If the gravity dam deep sliding block is equal, the gravity dam deep sliding block reaches the ultimate equilibrium. Then in step S31, the gravity dam foundation as a whole and each block in each time step The calculation formula of the deep anti-sliding stability resistance ratio coefficient is: Where, represents the deep anti-sliding stability resistance coefficient of block i at time step j, represents the resistance function of block i at time step j, represents the effect function of block i at time step j, Indicates the standard value of material performance, Indicates the material performance partial coefficient, represents the standard value of geometric parameters, represents the structural importance coefficient, represents the ultimate limit state structural coefficient of deep anti-sliding stability bearing capacity, represents the design condition coefficient, represents the permanent action partial coefficient, Indicates the permanent effect standard value, represents the variable action partial coefficient, Indicates the standard value of variable action.

[0028] Ratio coefficient of resistance action of each strip Are equal, we can get: For the deep anti-sliding section of the same dam, are the same, then in step S32, the simplified deep anti-sliding stability resistance ratio coefficient The calculation formula is: Where, , ,…, Respectively represent the resistance function of blocks i~N at time step j, , ,…, Represents the effect function of blocks i~N at time step j.

[0029] In step S33, at each time step Available about of The equation is combined with the equilibrium equation of the internal force of the deep anti-sliding system of the dam foundation: You can get About The equation of each time step can be obtained by solving Shear force between the lateral contact surfaces of each strip .

[0030] In step S34, Substitute the resistance ratio The calculation formula is used to obtain the ratio coefficient of the deep anti-sliding stability resistance of the gravity dam at each time step j .

[0031] In step S4 of the embodiment of the present invention, when the minimum deep anti-slip stability ratio coefficient When , the gravity dam is in the deep sliding stability range and has deep anti-sliding stability; specifically, When the deep anti-sliding stability ratio coefficient is And its corresponding cumulative duration and total duration ratio in Figure 3 Outside the shaded area, the gravity dam maintains deep anti-sliding stability.

[0032] In step S4 of the embodiment of the present invention, when the minimum deep anti-slip stability ratio coefficient According to the cumulative duration of the deep anti-sliding stability coefficient of each time step , analyze the deep anti-sliding stability of gravity dams; the analysis process is as follows: When it appears Cumulative duration When the gravity dam is outside the deep sliding stability range, the nonlinear contact between the dam body, deep sliding block and foundation is considered, and the deep anti-sliding stability of the medium gravity dam is further evaluated through nonlinear time history response analysis; specifically, Cumulative duration When the deep anti-sliding stability ratio coefficient is and its corresponding cumulative duration in Figure 3 Within the shaded area, the gravity dam may experience deep sliding instability, which requires further evaluation using nonlinear time history analysis; When it appears Cumulative duration and total duration The proportion of Less than When the gravity dam is in the deep sliding stability range, it has deep anti-sliding stability; specifically, the deep anti-sliding stability ratio coefficient in the entire earthquake motion history is and its corresponding cumulative duration in Figure 3 Outside the shaded area, the gravity dam can maintain deep anti-sliding stability; When it appears Cumulative duration and total duration The proportion of Greater than When the gravity dam is outside the deep sliding stability range, the nonlinear contact between the dam body, deep sliding block and foundation is considered, and the deep anti-sliding stability of the medium gravity dam is further evaluated through nonlinear time history response analysis; specifically, the deep anti-sliding stability ratio coefficient in the entire earthquake motion time history is and its corresponding cumulative duration in Figure 3 Within the shaded area, the gravity dam may experience deep sliding instability, which requires further evaluation using nonlinear time history analysis; in, and All are set constants less than 1.

[0033] In this embodiment, the method for further evaluating the deep anti-sliding stability of the medium gravity dam is specifically as follows: For the finite element analysis model of the dam-foundation system, a contact model is used to consider the nonlinearity between the dam body, deep sliding block and foundation, and a nonlinear dynamic time-history response analysis is performed taking into account the radiation damping foundation effect; According to the results of nonlinear dynamic time-history response analysis, the sum of the sliding areas of each sliding surface of the deep sliding block is calculated. Total sliding surface area Proportion ; judge Is it established? To set the threshold, the value range is 0~1; If so, the gravity dam is within the deep sliding stability range and has deep anti-sliding stability; If not, the gravity dam is at risk of deep anti-sliding instability failure and needs to be strengthened. After the strengthening treatment, the previous assessment steps should be repeated.

[0034] In this embodiment, the total sliding surface area The calculation formula is: The sum of the sliding areas of each sliding surface of the deep sliding block The calculation formula is: Where, Indicates the influence area of ​​each contact point on the contact surface, is the area affected by the contact point where sliding failure occurs on the contact surface, is the total number of contact points.

[0035] Specific embodiments are used in the present invention to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

[0036] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific descriptions and embodiments. Those skilled in the art can make various other specific variations and combinations based on the technical teachings disclosed in the present invention without departing from the essence of the present invention, and such variations and combinations are still within the scope of protection of the present invention.

Claims

1. A method for assessing the deep anti-sliding stability of a gravity dam with complex sliding surfaces in a strong earthquake zone is characterized by: The following steps are involved: S1. Construct a finite element analysis model of the dam-foundation system with a deep sliding block consisting of weak structural surfaces within the foundation rock mass; S2. Based on the constructed finite element analysis model of the dam-foundation system, the dam-deep sliding block is divided vertically into strips equal to the number of deep sliding block structural surfaces at each boundary of the deep sliding block structural surface; S3. Extract the dynamic internal force of the sliding surface of each block at each time step, and use it together with the static load acting on each block as the external force. Calculate the deep anti-sliding stability resistance ratio coefficient of the gravity dam step by step at each time step, and draw a time history curve of the deep anti-sliding stability ratio coefficient. S4. Evaluate the deep anti-sliding stability of the gravity dam based on the minimum deep anti-sliding stability ratio coefficient in the time history curve.

2. The method for evaluating the deep anti-sliding stability of a gravity dam with complex sliding surfaces in a strong earthquake zone according to claim 1 is characterized in that: In step S3, the method for solving the ratio coefficient of deep anti-sliding stability resistance of gravity dam is specifically as follows: S31. Based on the resistance function and action effect function of strip i at time step j, a calculation formula for the deep anti-sliding stability resistance action ratio coefficient of the entire gravity dam foundation at each time step is constructed; S32. Based on the fact that the deep anti-sliding stability resistance ratio coefficients of all blocks are equal, the calculation formula for the deep anti-sliding stability resistance ratio coefficient is simplified; S33. Based on the calculation formula of the deep anti-sliding stability resistance coefficient of each block, N-1 equations about the sum of the shear forces on both sides of the strip i are constructed at each time step j, and combined with the balance formula of the internal force of the deep anti-sliding system of the gravity dam foundation, the solution is obtained for each time step. The sum of the shear forces between the lateral contact surfaces of each strip ; S34, will Substitute the calculation formula of the deep anti-sliding stability resistance ratio coefficient into the solution to obtain the deep anti-sliding stability resistance ratio coefficient of the gravity dam at each time step j.

3. The method for evaluating the deep anti-sliding stability of a gravity dam with complex sliding surfaces in a strong earthquake zone according to claim 2 is characterized in that: In step S31, the deep anti-slip stability resistance ratio coefficient The calculation formula is: Where, represents the deep anti-sliding stability resistance coefficient of block i at time step j, represents the resistance function of block i at time step j, represents the effect function of block i at time step j, Indicates the standard value of material performance, Indicates the material performance partial coefficient, represents the standard value of geometric parameters, represents the structural importance coefficient, represents the ultimate limit state structural coefficient of deep anti-sliding stability bearing capacity, represents the design condition coefficient, represents the permanent action partial coefficient, Indicates the permanent effect standard value, represents the variable action partial coefficient, Indicates the standard value of variable action.

4. The method for evaluating the deep anti-sliding stability of a gravity dam with complex sliding surfaces in a strong earthquake zone according to claim 3 is characterized in that: In step S32, the simplified deep anti-sliding stability resistance ratio coefficient The calculation formula is: Where, , ,…, Respectively represent the resistance function of blocks i~N at time step j, , ,…, Represents the effect function of blocks i~N at time step j.

5. The method for evaluating the deep anti-sliding stability of a gravity dam with complex sliding surfaces in a strong earthquake zone according to claim 1 is characterized in that: In step S4, when the minimum deep anti-slip stability ratio coefficient When , the gravity dam is in the deep sliding stability range and has deep anti-sliding stability; When the minimum deep anti-sliding stability ratio coefficient According to the cumulative duration of the deep anti-sliding stability coefficient of each time step , analyze the deep anti-sliding stability of gravity dams.

6. The method for evaluating the deep anti-sliding stability of a gravity dam with complex sliding surfaces in a strong earthquake zone according to claim 1 is characterized in that: In step S4, when Cumulative duration When the gravity dam is outside the deep sliding stability range, the nonlinear contact between the dam body, deep sliding block and foundation is considered, and the deep anti-sliding stability of the medium gravity dam is further evaluated through nonlinear time history response analysis; When it appears Cumulative duration and total duration The proportion of Less than When , the gravity dam is in the deep sliding stability range and has deep anti-sliding stability; When it appears Cumulative duration and total duration The proportion of Greater than When the gravity dam is outside the deep sliding stability range, the nonlinear contact between the dam body, deep sliding block and foundation is considered, and the deep anti-sliding stability of the medium gravity dam is further evaluated through nonlinear time history response analysis; in, and All are set constants less than 1.

7. The method for evaluating the deep anti-sliding stability of a gravity dam with complex sliding surfaces in a strong earthquake zone according to claim 6 is characterized in that: The method for further evaluating the deep anti-sliding stability of medium gravity dams is as follows: For the finite element analysis model of the dam-foundation system, a contact model is used to consider the nonlinearity between the dam body, deep sliding block and foundation, and a nonlinear dynamic time-history response analysis is performed taking into account the radiation damping foundation effect; According to the results of nonlinear dynamic time history response analysis, the sum of the sliding areas of each sliding surface of the deep sliding block is calculated. Total sliding surface area Proportion ; judge Is it established? To set the threshold; If so, the gravity dam is within the deep sliding stability range and has deep anti-sliding stability; If not, the gravity dam is at risk of deep anti-sliding instability failure and needs to be strengthened.

8. The method for evaluating the deep anti-sliding stability of a gravity dam with complex sliding surfaces in a strong earthquake zone according to claim 7 is characterized in that: The total sliding surface area The calculation formula is: The sum of the sliding areas of the sliding surfaces of the deep sliding block The calculation formula is: Where, Indicates the influence area of ​​each contact point on the contact surface, is the area affected by the contact point where sliding failure occurs on the contact surface, is the total number of contact points.

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