Gravity dam face crack cause analysis method and device

Abstract

The invention discloses a gravity dam face crack cause analysis method and device, relates to the field of water conservancy projects, and aims to improve the accuracy and efficiency of dam body crack cause analysis. The method comprises the following steps: establishing a nonlinear finite element model of a gravity dam body, and confirming a load applied by simulation; analyzing the stress influence of the downstream facade crack part of the dam body under the action of a single load, and analyzing the stress change rule of the downstream facade crack part of the dam body under the combined action of multiple loads; analyzing the influence of excessive highest temperature of concrete at the crack part of the downstream facade of the dam body on stress; analyzing the influence of reinforcing bars of a guide wall and a surface hole overflow surface on the stress of the crack part of the downstream facade of the dam body; and finally, comprehensively analyzing the cause of the dam body downstream facade crack. According to the method, the accuracy, reliability and efficiency of fracture cause analysis are improved.

Description

Technical Field

[0001] The invention relates to the field of water conservancy engineering, and in particular to a method and a device for analyzing causes of cracks on a gravity dam surface. Background Art

[0002] In the field of water conservancy and hydropower engineering, gravity dams are a common type of dam, and their structural safety is of vital importance. However, during the construction and operation of gravity dams, due to the influence of various factors such as temperature changes, water pressure, deadweight, flood discharge pulsation, etc., cracks on the dam surface often occur, seriously affecting the stability and durability of the dam. Therefore, analyzing the causes of cracks on the dam surface of gravity dams and formulating corresponding compensatory measures are of great significance to ensure the safe operation of the dam.

[0003] At present, the analysis of the causes of cracks on the surface of gravity dams mostly relies on traditional experimental and theoretical calculation methods. These methods often have certain limitations, such as difficulty in simulating the complex crack propagation process and limited guidance for actual engineering projects.

[0004] Traditional methods for analyzing the causes of cracks on the surface of gravity dams mainly include field monitoring, laboratory tests, and theoretical analysis. These methods can provide information on the development of cracks to a certain extent, but they often have problems such as difficulty in data collection, complex analysis process, and difficulty in fully considering various influencing factors. For example, although field monitoring can provide real-time data, it is costly and greatly affected by environmental factors, and the analysis efficiency is also low; laboratory tests are difficult to simulate the actual working environment of the dam, resulting in limited applicability and poor accuracy of the results; and theoretical analysis is often based on simplified assumptions and it is difficult to accurately predict the development of cracks. In addition, these traditional methods are also unable to deal with the diversity and complexity of the causes of cracks, especially when faced with dynamic loads such as flood discharge pulsation, temperature changes, and water level rise and fall, the accuracy and reliability of their analysis are even more challenged. Therefore, a more practical and accurate method for analyzing the causes of cracks is still needed. Summary of the invention

[0005] The object of the present invention is to provide a method and device for analyzing the causes of cracks on the dam surface of a gravity dam in order to improve the accuracy and efficiency of the analysis of the causes of cracks on the dam body in order to solve all or part of the above-mentioned problems.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A method for analyzing causes of cracks on a gravity dam surface, comprising:

[0008] S1. Establish a nonlinear finite element model of the gravity dam body and confirm the load applied by simulation;

[0009] S2. Analyze the stress influence of cracks on the downstream vertical surface of the dam under single load;

[0010] S3. Analyze the stress variation law of the cracks on the downstream vertical surface of the dam under the combined action of multiple loads;

[0011] S4. Analyze the influence of the maximum temperature of concrete exceeding the standard on the stress at the crack part of the downstream vertical surface of the dam body;

[0012] S5. Analyze the influence of the reinforcement of the guide wall and the overflow surface of the surface hole on the stress of the cracks on the downstream vertical surface of the dam body;

[0013] S6. Based on the analysis results of steps S2-S5, a comprehensive analysis of the causes of the cracks on the downstream facade of the dam body is conducted.

[0014] Furthermore, in step S1, it is confirmed that the loads applied in the simulation include the deadweight of the structure, hydrostatic pressure, temperature load and flood discharge pulsation load.

[0015] Furthermore, the stress influence analysis of the crack position on the downstream vertical surface of the dam body under the single load in step S2 includes:

[0016] Transverse river stress envelope diagram for the analysis of the effect of single load on the stress at the cracks on the downstream vertical surface of the dam;

[0017] Stress change process line of the crack part at each elevation point;

[0018] A statistical table of transverse river tensile stress at crack locations at various elevation points on the downstream surface of the dam body.

[0019] Furthermore, in step S2, the analysis of the impact of temperature load includes the analysis of the impact of temperature load during the construction period and the analysis of the impact of temperature load during the operation period; wherein,

[0020] Analysis of the influence of temperature load during construction period: by simulating the construction process of the dam, applying unstable temperature field during the simulation, and conducting comparative analysis of transverse stress of concrete before and after thermal insulation;

[0021] The analysis of the influence of temperature load during operation is to calculate the concrete stress under the influence of short-term temperature drop load during operation.

[0022] Furthermore, the step S3 includes:

[0023] Taking into account the deadweight of the structure, hydrostatic pressure, and temperature loads during construction and operation, a full-process simulation method was adopted to simulate the changes in concrete stress since the pouring of the dam, and to calculate the stress value at the cracks on the downstream facade of the dam body.

[0024] Furthermore, in step S4, by increasing the concrete pouring temperature, the working condition where the maximum temperature of the dam concrete exceeds the standard is simulated, and the tensile stress values ​​of the downstream vertical surface concrete of the dam body are calculated and compared under the working condition where the maximum temperature exceeds the standard and the working condition where the maximum temperature does not exceed the standard.

[0025] Furthermore, the step S5 comprises:

[0026] The material parameters of the orifice, gate pier and central guide wall are corrected according to the actual reinforcement ratio, and the tensile stress value of the crack on the downstream vertical surface of the dam body is calculated according to the corrected material parameters.

[0027] The present invention also provides a device for analyzing the causes of cracks on the surface of a gravity dam, comprising a processor and a storage medium, wherein the processor runs a computer program stored in the storage medium to execute the above-mentioned method for analyzing the causes of cracks on the surface of a gravity dam.

[0028] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0029] Compared with the prior art, the present invention has the following significant effects:

[0030] 1. The present invention uses the finite element full-process simulation technology to comprehensively analyze the influence of structural deadweight, hydrostatic pressure, temperature load and flood discharge pulsation load on the cracks on the gravity dam surface, thereby improving the accuracy and reliability of the crack cause analysis;

[0031] 2. The present invention comprehensively considers the maximum temperature exceeding the standard of concrete and the influence of reinforcement during the construction period, more accurately simulates the actual working conditions, and enhances the practical application value of the analysis results;

[0032] 3. The present invention can identify the main causes of dam surface cracks through qualitative and quantitative analysis of different loads and working conditions, providing a scientific basis for the maintenance and repair of the dam;

[0033] 4. The present invention can effectively predict the development of cracks on the dam surface, providing a new technical means for dam safety management;

[0034] 5. The present invention reduces the need for on-site testing, reduces costs and improves efficiency through simulation analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0036] Figure 1 It is a flow chart of the method for analyzing the causes of cracks on the surface of a gravity dam proposed in an embodiment of the present application.

[0037] Figure 2 It is a transverse river stress envelope diagram of the downstream vertical crack position of the gravity dam body under a single load in the embodiment of the present application.

[0038] Figure 3 It is a line diagram of the cross-river stress change process at the downstream vertical crack position of the gravity dam body under the action of a single load in the embodiment of the present application.

[0039] Figure 4 It is a statistical table of transverse river stress at the downstream vertical crack position of the gravity dam body under a single load in the embodiment of the present application.

[0040] Figure 5 It is a schematic diagram of the area where the maximum temperature of the concrete of the gravity dam body exceeds the standard in the embodiment of the present application.

[0041] Figure 6 It is a diagram of the internal transverse stress process at the downstream vertical crack position of the gravity dam body under a single load in the embodiment of the present application, taking into account the excessive maximum temperature of concrete.

[0042] Figure 7 It is the maximum transverse stress envelope diagram of the downstream vertical crack position of the gravity dam body under a single load in the embodiment of the present application, taking into account the influence of reinforcement.

[0043] Figure 8 It is a transverse stress process line diagram of the typical elevation of the downstream vertical crack position of the gravity dam body under a single load in the embodiment of the present application, taking into account the influence of reinforcement. DETAILED DESCRIPTION

[0044] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0045] Any feature disclosed in this specification (including any additional claims and abstract), unless otherwise stated, may be replaced by other equivalent or alternative features having similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0046] In view of the problem that the existing technology lacks comprehensiveness, practicality and accuracy in the analysis of the causes of cracks on the surface of gravity dams, the embodiment of the present application proposes a method for analyzing the causes of cracks on the surface of gravity dams based on finite element full-process simulation technology, which aims to accurately evaluate the causes of cracks in the dam body and improve the accuracy and efficiency of crack analysis, thereby providing a scientific basis for the safe operation and maintenance of gravity dams.

[0047] The method for analyzing the causes of cracks on the surface of a gravity dam proposed in this application is based on the boundary conditions and thermal and mechanical parameters obtained by inversion, and adopts a finite element full-process simulation method. By simulating the entire process of dam construction, initial storage and operation, the spatiotemporal evolution of temperature, deformation and stress of the dam concrete is simulated and analyzed. The influence of loads such as deadweight, water pressure, temperature and flood discharge pulsation on the stress of the downstream vertical crack position of the dam is comprehensively considered, the influence weight of each load on the formation of cracks is analyzed, and a special analysis is conducted on the excessive maximum temperature of the dam concrete and the influence of concrete reinforcement. Finally, considering the combined effect of multiple factors, the stress value and change law of the downstream vertical crack position are calculated, and the main causes of the downstream vertical cracks of the flood discharge dam body and the subsequent development of the cracks are analyzed and proposed.

[0048] In some embodiments, Figure 1 As shown in the figure, the cause analysis method of gravity dam surface cracks includes the following process:

[0049] S1. Establish a nonlinear finite element model of the gravity dam body and confirm the load applied in the simulation.

[0050] This step S1 is the preparatory stage for simulating the entire process of dam construction, initial storage and operation. In this step, the nonlinear finite element model of the gravity dam is established based on the engineering construction data, boundary conditions, thermal and mechanical parameters, etc. In the preparation work for the full-process nonlinear finite element simulation, the main loads that affect the stress level of the downstream vertical cracks of the dam body are identified by analyzing the engineering data and combining engineering experience, in order to prepare for the later simulation analysis.

[0051] In some embodiments, by analyzing engineering data and combining engineering experience, it is confirmed that the main loads that affect the stress level at the crack site of the downstream facade of the dam body include: structural deadweight, hydrostatic pressure, temperature load and flood discharge pulsation load.

[0052] S2. Analyze the influence of stress on the cracks on the downstream vertical surface of the dam under the action of a single load.

[0053] This step is based on the finite element model established in step S1 and the confirmed loads, and calculates the influence of each load that affects the stress level of the downstream vertical crack of the dam body on the stress of the downstream vertical crack of the dam. The influence weight of each load on the formation of cracks is analyzed to obtain the change law of concrete stress at the crack site under a single load.

[0054] Taking the loads confirmed in the previous embodiments (structural deadweight, hydrostatic pressure, temperature load and flood discharge pulsation load) as an example, in some embodiments, the influence of each load on the stress of the crack part of the downstream facade of the dam is analyzed one by one.

[0055] 1) The influence of the structure’s own weight.

[0056] The deadweight of the structure mainly comes from the concrete of the dam body. During the construction period, as the concrete is poured in compartments, the dam body gradually rises, and the stress level at the cracks gradually increases. By using SAPTIS software to simulate the concrete pouring process, the concrete stress at the cracks on the downstream facade of the dam body caused by the deadweight of the structure is calculated.

[0057] 2) Influence of hydrostatic pressure.

[0058] The concrete stress at the crack of the downstream vertical surface of the dam body is calculated under the action of the hydrostatic pressure on the upstream and downstream dam surfaces, the water thrust acting on the gate, and the pressure acting on the area before the water stop on the transverse joint surface.

[0059] 3) Influence of temperature load.

[0060] During the construction and operation period, when the concrete surface is not insulated in time or encounters a sudden temperature drop load, a large internal and external temperature difference will be generated, which will lead to a large temperature stress on the concrete surface. When analyzing the influence of temperature load, the whole process simulation process of the temperature load influence calculation during the construction period is first carried out. By simulating the construction process of the dam body, the concrete jump bin pouring process, hydration heat release process, hardening process, water cooling process and surface insulation are considered. According to the actual measured ambient temperature, an unstable temperature field is applied when simulating the construction process, the temperature stress of the dam concrete is calculated, and the horizontal stress before and after the concrete insulation is compared and analyzed. After entering the operation period, the temperature field of the dam gradually transitions to a stable temperature field, but when encountering short-term temperature drop loads such as cold waves, the internal and external temperature difference will increase rapidly, which will still affect the temperature stress of the concrete surface. Therefore, the analysis of the influence of temperature load during the operation period is to calculate the concrete stress under the influence of short-term temperature drop loads (such as cold waves) during the operation period. The calculation process simulates the temporal and spatial distribution and evolution of the temperature stress on the downstream facade of the dam during operation based on the actual measured ambient temperature changes, and calculates the temperature stress of the dam concrete.

[0061] 4) Influence of flood discharge pulsating load.

[0062] Considering the pulsating load of flood discharge on the dam body, the pulsating load of flood discharge is applied to the support hinge of the arc gate of the surface hole. The dynamic time history analysis is performed using the Newmark step-by-step integration method, with a calculation time step of 0.002s and a total of 2500 steps. In the dynamic time history analysis, Rayleigh damping is used to simulate the damping effect of the structure. According to the specification, the damping ratio of the gravity dam is 10%. In this way, the transverse stress time history curve of the crack surface of the downstream vertical surface of the dam body under the action of the pulsating load of flood discharge is calculated, that is, the transverse stress of the crack surface of the downstream vertical surface of the dam body is obtained.

[0063] The above analysis and calculation of the influence of each single load results in the following: Figure 2The cross-river stress envelope diagram of the single load effect on the stress analysis of the downstream vertical crack of the dam body is shown in Figure 3 The stress change process lines at the cracks at various elevation points are shown, as well as Figure 4 The following is a statistical chart of the tensile stress in the cross-river direction at the cracks at various elevation points on the downstream surface of the dam body. Figure 2 (a) Figure 2 (b) Figure 2 (c) and Figure 2 (d) Transverse stress envelope diagrams under structural deadweight, hydrostatic pressure, construction temperature load, and operation temperature load, respectively; Figure 3 (a) Figure 3 (b) Figure 3 (c) and Figure 3 (d) is a graph showing the stress variation process in the transverse direction when considering only the structural deadweight (elevation 340), hydrostatic pressure (elevation 334), temperature load during construction (elevation 349) and temperature load during operation (elevation 349); Figure 4 (a) and Figure 4 (b) are the statistical diagrams of the maximum transverse stress at different elevations of the crack under the load of the structure alone and the hydrostatic pressure alone. Figure 4 (c) is a statistical table of tensile stress in the river direction at an elevation of 349m on the downstream side of the dam. Figure 4 (d) is the time history curve of the surface hole flood discharge pulsating load. Figures 2 to 4 The data can reveal the changing trend and distribution of tensile stress on the downstream facade of the dam, as well as the maximum tensile stress value at the selected elevation point, so that a preliminary analysis can be made of the main influencing factors leading to cracking on the downstream facade.

[0064] S3. Analyze the stress variation law of the cracks on the downstream vertical surface of the dam under the combined action of multiple loads.

[0065] Based on the analysis of the single load effect in step S2, step S3 comprehensively considers the effects of multiple loads. The whole process simulation method is used to simulate the changes in concrete stress since the dam was poured, and the stress value of the cracks on the downstream facade of the dam body is calculated.

[0066] In step S3, the structure's deadweight, hydrostatic pressure, and temperature loads during construction and operation are comprehensively considered, and a full-process simulation method is used to simulate the changes in concrete stress since the dam was poured, and the stress value at the crack on the downstream facade of the dam is calculated.

[0067] By analyzing the cross-river tensile stress statistics, stress process lines and temperature stress envelope diagrams during operation at the downstream vertical cracks of the dam body obtained by comprehensive analysis of multiple loads, the value of the maximum tensile stress at the downstream vertical cracks of the dam body and its elevation position are determined. The analysis method and analysis framework used in step S3 are the same as those used in step S2 to ensure the coherence and consistency of the analysis.

[0068] S4. Analyze the influence of the maximum temperature of concrete exceeding the standard at the crack part of the downstream vertical surface of the dam body on the stress.

[0069] Based on the simulation calculation results of step S1 and step S3, step S4 considers the situation that the maximum temperature of concrete exceeds the standard during the construction period. By increasing the concrete pouring temperature, the working condition of the maximum temperature of the dam concrete exceeding the standard is simulated, and the tensile stress value of the concrete on the downstream vertical surface of the dam body is calculated and compared under the working condition of the maximum temperature exceeding the standard and the working condition of not exceeding the standard.

[0070] Figure 5 The figure shows a schematic diagram of the area where the maximum temperature of concrete exceeds the standard. According to the analysis of engineering data, the maximum temperature of concrete in the dam body exceeds the standard during the construction period. The excessive maximum temperature of concrete during the construction period will increase the temperature drop of concrete during the operation period, generate large tensile stress, and then cause concrete cracking. Based on the calculation results of step S2 and step S3, by increasing the concrete pouring temperature, further simulate the working condition where the maximum temperature of the dam body concrete exceeds the standard, and calculate and compare the tensile stress value of the concrete on the downstream facade of the dam body. Figure 6 As shown in the figure, by comparing and analyzing the calculation results of the conditions where the maximum temperature exceeds the standard and the conditions where it does not exceed the standard, the internal lateral tensile stress increases, and it can be determined that exceeding the maximum temperature may aggravate the expansion depth of the cracks.

[0071] S5. Analyze the influence of the reinforcement of the guide wall and the overflow surface of the surface hole on the stress of the cracks on the downstream vertical surface of the dam body.

[0072] Based on the results calculated in step S2 and step S3, the influence of reinforcement is further considered. The material parameters of the orifice, gate pier and middle guide wall are corrected according to the actual reinforcement ratio, and the tensile stress value of the crack on the downstream facade of the dam body is calculated according to the corrected material parameters.

[0073] In actual projects, a large number of steel bars are arranged near the orifices, gate piers and middle guide walls. The linear expansion coefficient and elastic modulus of steel bars are greater than those of concrete. When the influence of steel bars is considered, the above-mentioned areas shrink more after encountering temperature drop loads, which may cause tensile stress increments on the downstream facade. Based on the calculation results of steps S2 and S3, the influence of reinforcement is further considered. The material parameters of the above-mentioned areas (i.e., the orifices, gate piers and middle guide walls) are corrected according to the actual reinforcement ratio, and the corrected equivalent parameters are used to calculate the tensile stress value at the crack site on the downstream facade of the dam body. Combined with Figure 7 and Figure 8A comparison chart of Figure 7 The left sub-figure does not consider the influence of reinforcement. Figure 7 The right sub-figure considers the influence of reinforcement; using the same data analysis framework as step S4, after considering the influence of reinforcement, the tensile stress of the downstream facade increases, and the increase is between 0.03MPa and 0.07MPa. It can be determined that the reinforcement has an impact on the tensile stress of the downstream facade of the dam body, but the impact is small.

[0074] S6. Based on the analysis results of steps S2-S5, a comprehensive analysis of the causes of the cracks on the downstream facade of the dam body is conducted.

[0075] Based on the simulation analysis and special analysis results from step S1 to step S5, all loads are integrated to conduct a qualitative and quantitative comprehensive analysis of the causes of cracks on the downstream facade of the dam body.

[0076] On the basis of completing the analysis of the above steps S1 to S5, the present step S6 aims to use the existing data and integrate the analysis results of all influencing factors to determine the main causes of the cracks on the downstream facade of the dam body.

[0077] According to the method introduced in the above embodiment, based on the simulation calculation results of the whole process of construction and operation of a gravity dam, the causes of concrete cracks on the downstream facade of the dam are analyzed as follows:

[0078] 1) The deadweight of the structure will produce less tensile stress in the downstream vertical area of ​​the dam body.

[0079] 2) The hydrostatic pressure load acts on the upstream and downstream dam surfaces, gates and the area before the transverse joint water stop, and the tensile stress generated in the downstream vertical area of ​​the dam body is relatively small.

[0080] 3) The temperature load during the construction period caused large tensile stress in the downstream vertical area of ​​the dam body, especially before the insulation cover, the maximum tensile stress was about 2.37MPa; although the dam surface was covered with insulation boards during the operation period, which could withstand the influence of conventional annual temperature changes, when encountering temperature drop loads such as cold waves (recorded in January 2016), the downstream vertical surface of the dam body would still produce large tensile stress, with a maximum of about 2.38MPa.

[0081] 4) Under the action of flood discharge pulsating load, the maximum transverse tensile stress on the surface of the downstream vertical crack is 0.00027MPa, indicating that the flood discharge vibration has little effect on the transverse stress of the downstream vertical surface of the dam body.

[0082] 5) Taking into account the effects of structural deadweight, hydrostatic pressure, temperature load, etc., the maximum tensile stress at the crack of the downstream vertical surface of the dam body after load superposition is about 2.48MPa.

[0083] 6) Exceeding the maximum temperature of concrete during construction will cause the internal transverse tensile stress to increase from 1.29MPa to 1.42MPa, which is sufficient to intensify the expansion of cracks into depth.

[0084] 7) After considering the influence of reinforcement in the orifice, gate pier, middle guide wall and other areas, the downstream vertical surface of the dam body will produce a tensile stress increment of 0.03MPa to 0.07MPa, and the influence of reinforcement on the tensile stress of the downstream vertical surface of the dam body is relatively small.

[0085] In summary, qualitative and quantitative analysis indicate that temperature stress during the construction and operation periods is the main cause of concrete cracking on the downstream facade of the spillway body.

[0086] An embodiment of the present application also proposes a device for analyzing the causes of cracks on the surface of a gravity dam, comprising a processor and a storage medium; the storage medium stores a computer program, and the processor runs the computer program stored in the storage medium to execute the method for analyzing the causes of cracks on the surface of a gravity dam in the above embodiment.

[0087] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A method for analyzing the causes of cracks on a gravity dam surface, characterized in that: include: S1. Establish a nonlinear finite element model of the gravity dam body and confirm the load applied by simulation; S2. Analyze the stress influence of cracks on the downstream vertical surface of the dam under single load; S3. Analyze the stress variation law of the cracks on the downstream vertical surface of the dam under the combined action of multiple loads; S4. Analyze the influence of the maximum temperature of concrete exceeding the standard on the stress at the crack part of the downstream vertical surface of the dam body; S5. Analyze the influence of the reinforcement of the guide wall and the overflow surface of the surface hole on the stress of the cracks on the downstream vertical surface of the dam body; S6. Based on the analysis results of steps S2-S5, a comprehensive analysis of the causes of the cracks on the downstream facade of the dam body is conducted.

2. The method for analyzing the causes of cracks on the surface of a gravity dam according to claim 1, characterized in that: In the step S1, it is confirmed that the loads applied in the simulation include the deadweight of the structure, hydrostatic pressure, temperature load and flood discharge pulsation load.

3. The method for analyzing the causes of cracks on the surface of a gravity dam according to claim 2, characterized in that: The stress influence analysis of the crack position on the downstream vertical surface of the dam body under the single load in step S2 includes: Transverse river stress envelope diagram for the analysis of the effect of single load on the stress at the cracks on the downstream vertical surface of the dam; Stress change process line of the crack part at each elevation point; A statistical table of transverse river tensile stress at crack locations at various elevation points on the downstream surface of the dam body.

4. The method for analyzing the causes of cracks on the surface of a gravity dam according to claim 2 or 3, characterized in that: In step S2, the analysis of the impact of temperature load includes the analysis of the impact of temperature load during the construction period and the analysis of the impact of temperature load during the operation period; wherein, Analysis of the influence of temperature load during construction period: by simulating the construction process of the dam, applying unstable temperature field during the simulation, and conducting comparative analysis of transverse stress of concrete before and after thermal insulation; The analysis of the influence of temperature load during operation is to calculate the concrete stress under the influence of short-term temperature drop load during operation.

5. The method for analyzing the causes of cracks on the surface of a gravity dam according to claim 2, characterized in that: The step S3 comprises: Taking into account the deadweight of the structure, hydrostatic pressure, and temperature loads during construction and operation, a full-process simulation method was adopted to simulate the changes in concrete stress since the pouring of the dam, and to calculate the stress value at the cracks on the downstream facade of the dam body.

6. The method for analyzing the causes of cracks on the surface of a gravity dam according to claim 1, characterized in that: In step S4, by increasing the concrete pouring temperature, the working condition where the maximum temperature of the dam concrete exceeds the standard is simulated, and the tensile stress values ​​of the downstream vertical surface concrete of the dam body are calculated and compared under the working condition where the maximum temperature exceeds the standard and the working condition where the maximum temperature does not exceed the standard.

7. The method for analyzing the causes of cracks on the surface of a gravity dam according to claim 1, characterized in that: The step S5 comprises: The material parameters of the orifice, gate pier and central guide wall are corrected according to the actual reinforcement ratio, and the tensile stress value of the crack on the downstream vertical surface of the dam body is calculated according to the corrected material parameters.

8. A device for analyzing the causes of cracks on a gravity dam surface, comprising a processor and a storage medium, characterized in that: The processor runs the computer program stored in the storage medium to execute the method for analyzing the causes of cracks on the surface of a gravity dam as described in any one of claims 1-7.

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