Method for detecting anti-sliding stability failure risk rate of tunnel plug in main flood season of super-high dam construction

Abstract

The present application relates to the technical field of water conservancy and hydropower engineering construction, and proposes a method for detecting the anti-sliding stability failure risk rate of a tunnel plug in the main flood season of super-high dam construction, which solves the problem of inaccurate and incomplete analysis results in the analysis scheme for the stability of the plug structure in the traditional technology. The present application first establishes an anti-sliding stability failure risk model of the tunnel plug in the main flood season of super-high dam construction; then determines the distribution parameters of the main random factors affecting the water load and the anti-sliding force; then, based on the designed length of the tunnel plug, combined with the distribution parameters of the main random factors affecting the water load and the anti-sliding force, the random simulation of the water load generated by the highest flood level of dam flood control in the main flood season and the total anti-sliding force that the tunnel plug can generate is carried out; finally, according to the random simulation results, the anti-sliding stability failure risk rate of the plug is estimated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water conservancy and hydropower engineering construction, in particular to a method for detecting the anti-sliding stability failure risk rate of a tunnel plug during the main flood season of a super-high dam construction. BACKGROUND

[0002] A number of super-high dams such as Shuangjiangkou, Yagen, Mengdigou, Yebatan, Gangduo, and Rumei, with a height of more than 200 meters, are being constructed or planned in the southwest region of China. These super-high dams are mostly built in the high mountain and canyon areas of the southwest region, and the construction diversion is generally achieved by cofferdam one-time flow interruption and tunnel diversion for whole-year construction of foundation pits. The construction of super-high dam hydropower projects is difficult and has a long construction period, and is affected by many uncertain factors during the construction process. The stability calculation and analysis of the plugs of tunnels such as water conservancy, transportation, construction branch tunnels, and temporary construction access have always been key technical problems in the design and research of underground engineering of large hydropower stations. With the continuous advancement of the construction of super-high dam hydropower projects in the southwest region, more and more super-high dams are facing the problem of the safety and stability of the plug structures of construction tunnels and water conservancy tunnels under the condition of passing through the main flood season during construction. For example, the lining of the ecological water supply tunnel of a 300-meter super-high core wall rockfill dam has not been completed before the flood season, and construction branch tunnel plugs need to be arranged to ensure that the water supply tunnel is not flooded and the construction safety is ensured during the main flood season.

[0003] At present, the conventional method for engineering and technical personnel to analyze the stability of the plug structure of a water conservancy tunnel is mainly to use the overall anti-sliding stability method and shear calculation method to review the stability of the designed tunnel plug structure. These methods are simple in principle and easy for engineering design personnel to accept.

[0004] However, the above-mentioned plug structure stability analysis method cannot reflect the influence of main random factors such as rock mechanics parameters, concrete parameters, and contact coefficients between sliding surface materials on the stability of the structure, and the analysis result is not accurate.

[0005] In recent years, with the development of water conservancy reliability theory, the limit state design method based on probability theory has been continuously applied in engineering design. Wang Kui et al. considered the influence of uncertainty factors in geotechnical engineering and introduced the reliability theory to calculate and analyze the stability of the designed water conservancy tunnel plug. However, for the tunnel plug structure that blocks water during the main flood season, on the one hand, this model mainly targets circular water conservancy tunnels and is not suitable for the more commonly used city gate type tunnels; on the other hand, the model ignores the randomness of the upstream water pressure load during the flood season, making the reliability analysis of the tunnel plug not comprehensive enough. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a method for detecting the anti-sliding stability failure risk rate of a tunnel plug during the main flood season of a super-high dam construction, which solves the problem of inaccurate and incomplete analysis results in the analysis scheme for the stability of the plug structure in the traditional technology.

[0007] The technical scheme adopted by the present application to solve the above technical problems is:

[0008] The method for detecting the anti-sliding stability failure risk rate of a tunnel plug in the main flood season of a super-high dam construction comprises the following steps:

[0009] S1, a model for the anti-sliding stability failure risk of a tunnel plug in the main flood season of a super-high dam construction is established;

[0010] S2, distribution parameters of main random factors affecting water load are determined;

[0011] S3, distribution parameters of main random factors affecting anti-sliding force are determined;

[0012] S4, based on the designed length of the tunnel plug, combined with the distribution parameters of the main random factors affecting water load and anti-sliding force, random simulation of water load generated by the highest flood control water level of the dam in the main flood season and the total anti-sliding force that the tunnel plug can generate is performed;

[0013] S5, according to the random simulation results, the anti-sliding stability failure risk rate of the tunnel plug in the main flood season of a super-high dam construction is estimated.

[0014] Further, in step S1, the model for the anti-sliding stability failure risk of a tunnel plug in the main flood season of a super-high dam construction is:

[0015] R=P(P H (max(Z m (t)))>f'∑W+C'(λA1+A2))

[0016] Wherein, R represents the anti-sliding stability failure risk of a tunnel plug in the main flood season of a super-high dam construction; Z m (t) represents the dynamic change process of the water level of the reservoir before the dam in the main flood season of the dam construction; P H (max(Z m (t))) is the thrust on the upstream face of the plug generated by the water load of the highest flood; f' is the shear fracture friction coefficient between the plug and the surrounding rock; ∑W is the total normal force on the sliding surface; C' is the cohesion between the plug and the concrete or the concrete and the surrounding rock; λ is the effective bonding area coefficient of the side wall; A1 is the effective shear surface contact area of the side wall; A2 is the effective shear surface contact area of the bottom surface; P(·) represents the probability of the condition (·) being true.

[0017] Further, in step S2, the distribution parameters of the main random factors affecting water load include:

[0018] The flood peak of the construction flood is assumed to follow a P-Ⅲ distribution;

[0019] The discharge capacity coefficient of the diversion tunnel is assumed to follow a triangular distribution;

[0020] The water level-storage capacity relationship coefficient is assumed to follow a triangular distribution.

[0021] Further, in step S3, the distribution parameters of the main random factors affecting the anti-sliding force are determined, including:

[0022] The bonding effective area coefficient of the side wall is assumed to follow a triangular distribution, and its probability density function is:

[0023]

[0024] wherein k d is the lower limit value, i.e., the minimum bonding effective area coefficient of the side wall; k m is the median value, which is estimated according to the technical level of the construction unit and the site management; and k u is the upper limit value, i.e., the maximum bonding effective area coefficient of the side wall.

[0025] The shear-friction coefficient and cohesion of the plug material are assumed to follow a normal distribution, and its probability density function is:

[0026]

[0027] wherein μ is the mean value of the random variable parameter of the shear-friction coefficient f' or the cohesion C'; and σ is the standard deviation of the random variable parameter of the shear-friction coefficient f' or the cohesion C'.

[0028] Further, in step S4, based on the designed length of the tunnel plug, the distribution parameters of the main random factors affecting the water load and the anti-sliding force are combined to perform random simulation of the total anti-sliding force that can be generated by the tunnel plug under the water load generated by the highest flood level of the dam during the main flood season, including:

[0029] First, based on the Monte Carlo method, the total number N C of model simulation calculations that meet the calculation accuracy requirement is determined.

[0030] Then, the distribution parameters of the main random factors affecting the water load and the anti-sliding force are combined to perform N C times of random simulation of the total anti-sliding force that can be generated by the tunnel plug under the water load generated by the highest flood level of the dam during the main flood season.

[0031] Further, the random simulation process of the water load generated by the highest flood level of the dam during the main flood season includes:

[0032] ① Generating a construction flood peak random number to simulate the construction flood process.

[0033] ② Generating a water reservoir storage capacity relationship coefficient random number to simulate the fitting water level-storage capacity relationship curve.

[0034] ③ Generate random numbers for the discharge capacity coefficient and simulate and fit the flow guidance and discharge capacity curve;

[0035] ④ The maximum flood level (max(Z)) in front of the dam during the main flood season is obtained through simulation of flood control calculations. m (t));

[0036] ⑤ Calculate the water load P by simulating the highest flood level in front of the dam during the main flood season. H (max(Z m (t))).

[0037] Furthermore, the stochastic simulation process of the total anti-skid force generated by the tunnel plug includes:

[0038] ① Generate a random number for the effective bonding area coefficient λ of the sidewall;

[0039] ② Generate random numbers for the shear friction coefficient f' and cohesion C';

[0040] ③ Calculate the total anti-skid force f'∑W+C'(λA1+A2) that the tunnel plug can generate.

[0041] Furthermore, in step S5, based on the results of random simulation, the risk rate of anti-sliding stability failure of the tunnel plug during the main flood season of the ultra-high dam construction is estimated, including:

[0042] According to N C The simulation results of the stochastic simulation of the water load generated by the highest flood level of the dam during the secondary flood season and the total anti-sliding force generated by the tunnel plug are statistically analyzed. H (max(Z m The number of times (t) exceeds the total anti-slip force f'∑W+C'(λA1+A2) that the tunnel plug can generate is denoted as N. T ;

[0043] Then according to Estimate the risk rate R of tunnel plug anti-sliding stability failure during the main flood season of ultra-high dam construction.

[0044] The beneficial effects of this invention are:

[0045] (1) This invention introduces risk analysis theory and methods to construct a mathematical model of the risk of anti-sliding stability failure of tunnel plugs before flood season in ultra-high dams. It considers the randomness of the main factors affecting water load and the randomness of the main factors affecting anti-sliding force, and estimates the risk rate of anti-sliding stability failure of tunnel plugs in a more scientific and reasonable way, thereby improving the accuracy and comprehensiveness of the anti-sliding stability assessment of the designed plug structure.

[0046] (2) The plug anti-sliding stability failure risk rate detection scheme based on the application can facilitate subsequent optimization design of the designed plug structure, so that the scale of the tunnel plug project is reduced under the condition of ensuring that the design requirements are met, thereby reducing the plug project investment, shortening the construction period, and having good social, economic and safety benefits. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 The figure is a flow chart of the tunnel plug anti-sliding stability failure risk rate detection method in the main flood season of the super-high dam construction. DETAILED DESCRIPTION

[0048] The application aims to provide a tunnel plug anti-sliding stability failure risk rate detection method in the main flood season of super-high dam construction, and solve the problem of inaccurate and incomplete analysis results in the analysis scheme of the stability of the plug structure in the prior art. First, a tunnel plug anti-sliding stability failure risk model in the main flood season of super-high dam construction is established; then, the distribution parameters of the main random factors are determined by systematically analyzing the randomness of the main factors affecting the water load and the anti-sliding force; then, the random simulation of the water load generated by the highest flood control flood level of the dam in the main flood season and the total anti-sliding force that the tunnel plug can generate is performed based on the designed length of the tunnel plug and in combination with the distribution parameters of the main random factors affecting the water load and the anti-sliding force; finally, the tunnel plug anti-sliding stability failure risk rate in the main flood season of super-high dam construction is estimated according to the random simulation results. This scheme can more scientifically and reasonably estimate the tunnel plug anti-sliding stability failure risk rate, and provide a scientific theoretical basis and technical support for subsequent determination of a suitable tunnel plug project scale, thereby reducing the project investment, ensuring the safety of construction during the flood season, and speeding up the project progress.

[0049] In the specific implementation, referring to Figure 1 The tunnel plug anti-sliding stability failure risk rate detection method in the main flood season of super-high dam construction provided by the application comprises the following implementation steps:

[0050] S1, establishing a tunnel plug anti-sliding stability failure risk model in the main flood season of super-high dam construction;

[0051] In this step, according to the theory of hydraulic structure and in combination with relevant regulations and specifications, taking the most commonly used city gate type tunnel plug in hydropower projects as an example, the tunnel plugging body sliding along the interface is the main structure failure mode of the tunnel plug. The load effect of the tunnel plug is mainly the thrust of the water load generated by the highest construction flood level on the upstream surface of the plug, and the structural resistance is the friction between the plug and the concrete or the concrete and the surrounding rock and the cohesion of the material. Based on this, the tunnel plug anti-sliding stability limit state equation in the main flood season of super-high dam construction can be described as:

[0052] Z=P H (max(Z m(t)))-(f'∑W+C'(λA1+A2))=0

[0053] wherein Z m (t) is the dynamic water level variation process of the reservoir flood regulation during the main flood season of the dam construction; P H (max(Z m (t))) is the thrust of the water load on the upstream face of the plug due to the highest flood level; f' is the shear-friction coefficient between the plug and the concrete or the concrete and the surrounding rock; ∑W is the sum of all normal forces on the sliding surface, in MN; C' is the cohesion between the plug and the concrete or the concrete and the surrounding rock, in MPa; λ is the bonding effective area coefficient of the side wall; A1 is the effective shear surface contact area of the side wall, in m 2 ; A2 is the effective shear surface contact area of the bottom surface, in m 2 .

[0054] Through research, the structural sliding failure risk of the tunnel plug during the construction flood season is mainly affected by the randomness of hydrology, hydraulics, material mechanics parameters, etc. Among them, the water load generated by the highest water level in the upstream reservoir area is affected by the randomness of hydrology, hydraulics, water level-storage capacity relationship, etc. The randomness of material mechanics parameters makes the total anti-sliding force of the plug have a certain randomness. In the present invention, the anti-sliding stability failure risk of the plug during the main flood season of the super-high dam construction is defined as the probability of the anti-sliding stability failure event of the tunnel plug caused by the water load generated by the highest flood level in the upstream during the main flood season of the construction. Therefore, considering the randomness of the main influencing factors, the mathematical model of the anti-sliding stability failure risk R of the tunnel plug before the flood season of the super-high dam is established as follows:

[0055] R=P(P H (max(Z m (t)))>f'∑W+C'(λA1+A2))

[0056] wherein R represents the anti-sliding stability failure risk of the tunnel plug during the main flood season of the super-high dam construction; Z m (t) represents the dynamic water level variation process of the reservoir flood regulation during the main flood season of the dam construction; P H (max(Z m (t))) is the thrust of the water load on the upstream face of the plug due to the highest flood level; f' is the shear-friction coefficient between the plug and the surrounding rock; ∑W is the sum of all normal forces on the control sliding surface; C' is the cohesion between the plug and the concrete or the concrete and the surrounding rock; λ is the bonding effective area coefficient of the side wall; A1 is the effective shear surface contact area of the side wall; A2 is the effective shear surface contact area of the bottom surface; P(·) represents the probability of the condition (·) being true.

[0057] S2, determining the distribution parameters of the main random factors affecting the water load;

[0058] In this step, the distribution parameters of the main random factors affecting the water load are determined by systematic analysis of the randomness of the main factors affecting the water load. The water load generated by the highest flood level is the only load on the plug structure. The cofferdam reservoir capacity of a super-high dam hydropower project is generally large, and the regulation and storage effect is obvious. The highest flood level before the dam during the main flood season is greatly random due to the randomness of hydrology and water power, specifically:

[0059] (1) Construction flood process randomness:

[0060] The construction flood process has randomness due to the randomness of precipitation in the catchment area upstream of the dam and the randomness of catchment time, etc. At present, the simulation of the construction flood process is basically based on the simulation of the flood peak, that is, the randomness of the construction flood peak is the basis for the simulation of the construction flood process. Therefore, for ease of calculation and analysis, the randomness of the flood peak is considered as the main hydrological random factor, and it is assumed to follow a P-III distribution. Based on the determination of the probability distribution model of the construction flood peak, the construction flood process is determined by the method of enlarging the typical flood process according to the flood peak flow value.

[0061] (2) Diversion tunnel discharge capacity randomness:

[0062] The discharge capacity of the construction diversion tunnel is influenced by many random factors such as the cross-sectional area of the tunnel, the wet perimeter, and the bottom slope. The discharge capacity density function curve is obtained by random simulation, and then the goodness of fit of the normal distribution and the triangular distribution is compared. It is considered that the discharge capacity of the diversion tunnel is closer to the triangular distribution.

[0063] (3) Water level-storage capacity relationship randomness:

[0064] Considering the influence of factors such as reservoir slope collapse and construction slag, the actual water level-storage capacity relationship also has randomness, and it is assumed that the reservoir capacity relationship coefficient also follows a triangular distribution.

[0065] S3, determine the distribution parameters of the main random factors affecting the anti-sliding force;

[0066] In this step, the distribution parameters of the main random factors affecting the anti-sliding force are determined by systematic analysis of the randomness of the main factors affecting the anti-sliding force, specifically:

[0067] (1) Side wall contact coefficient randomness:

[0068] The bonding effective area coefficient of the plug side wall of the city gate hole type tunnel influences the total anti-sliding force of the plug. However, the bonding effective area coefficient of the side wall has a certain randomness due to the influence of many uncertain factors such as concrete shrinkage, concrete pouring quality, grouting technical level, site construction management, construction equipment, etc. Generally, the bonding effective area coefficient is 0.3-0.8 according to the specific situation of the project. Since the value is within a certain range, and the technical strength of the construction unit and the site management situation can be combined in the actual project to give the preference of good and poor structure construction quality, the coefficient of good construction quality is large, and the coefficient of poor construction quality is small. Therefore, the bonding effective area coefficient λ of the side wall is assumed to be subject to a triangular distribution, and the probability density function is:

[0069]

[0070] wherein k d is the lower limit value, i.e. the minimum bonding effective area coefficient of the side wall; k m is the median value, which is estimated according to the technical level of the construction unit and the site management, and a larger value can be taken for good construction quality, and a smaller value can be taken for poor construction quality; and k u is the upper limit value, i.e. the maximum bonding effective area coefficient of the side wall.

[0071] (2) Randomness of material parameters:

[0072] According to the anti-sliding stability limit equation, the main material parameters affecting the total anti-sliding force are the random variable parameters of the shear friction coefficient f' and the cohesion C', and the probability density functions of the random variable parameters are assumed to be subject to normal distribution.

[0073]

[0074] wherein μ is the mean value of the random variable parameters of the shear friction coefficient f' or the cohesion C'; and σ is the standard deviation of the random variable parameters of the shear friction coefficient f' or the cohesion C'.

[0075] S4, based on the designed length of the tunnel plug, and combined with the distribution parameters of the main random factors affecting the water load and the anti-sliding force, the water load generated by the highest flood control flood level of the dam during the main flood period and the total anti-sliding force that can be generated by the tunnel plug are randomly simulated.

[0076] In this step, firstly, the total number of model simulation calculations N C that meets the calculation accuracy requirement is determined based on the Monte Carlo method; and then combined with the distribution parameters of the main random factors affecting the water load and the anti-sliding force, N C times of random simulation of the water load generated by the highest flood control flood level of the dam during the main flood period and the total anti-sliding force that can be generated by the tunnel plug are performed.

[0077] The stochastic simulation process for the water load generated by the highest flood level of the dam during the main flood season includes:

[0078] ① Generate random numbers for the peak flood during construction to simulate the construction flood process;

[0079] ② Generate random numbers for the reservoir capacity relationship coefficients and simulate and fit the water level-capacity relationship curve;

[0080] ③ Generate random numbers for the discharge capacity coefficient and simulate and fit the flow guidance and discharge capacity curve;

[0081] ④ The maximum flood level (max(Z)) in front of the dam during the main flood season is obtained through simulation of flood control calculations. m (t));

[0082] ⑤ Calculate the water load P by simulating the highest flood level in front of the dam during the main flood season. H (max(Z m (t))).

[0083] The stochastic simulation process of the total anti-skid force generated by the tunnel plug includes:

[0084] ① Generate a random number for the effective bonding area coefficient λ of the sidewall;

[0085] ② Generate random numbers for the shear friction coefficient f' and cohesion C';

[0086] ③ Calculate the total anti-skid force f'∑W+C'(λA1+A2) that the tunnel plug can generate.

[0087] Based on the above simulation process, N can be obtained. C The stochastic simulation results of the water load generated by the highest flood level of the dam during the main flood season and N C Simulation results of the total anti-skid force generated by a tunnel plug.

[0088] S5. Based on the results of random simulation, estimate the risk rate of anti-sliding stability failure of tunnel plugs during the main flood season of ultra-high dam construction;

[0089] In this step, according to N C The simulation results of the stochastic simulation of the water load generated by the highest flood level of the dam during the secondary flood season and the total anti-sliding force generated by the tunnel plug are statistically analyzed. H (max(Z m The number of times (t) exceeds the total anti-slip force f'∑W+C'(λA1+A2) that the tunnel plug can generate is denoted as N. T ;

[0090] Then according to Estimate the risk rate R of tunnel plug anti-sliding stability failure during the main flood season of ultra-high dam construction.

[0091] Embodiment

[0092] Taking the application of the scheme of the present application to the SJK hydropower station of the ultra-high core wall rockfill dam in the upper reaches of the Dadu River in China as an example, the tunnel plug anti-sliding stability failure risk rate detection method in the main flood season is exemplarily described.

[0093] The SJK hydropower station is a controlling reservoir in the upper reaches of the Dadu River in China, and the river dam is an ultra-high core wall rockfill dam with a dam height of 315.00 m, which is the highest dam in the world at present. The project is a first-class large (1) type project, and the hub project is composed of a river dam, a flood discharge structure, a water diversion and power generation system and the like. The project has steep valley slopes and exposed bedrock, and the tunnel diversion mode of cofferdam one-time cut-off and foundation pit all-year construction is adopted.

[0094] The project considers a special construction period ecological water supply tunnel for ecological water supply, maintenance, emergency and the like, and the engineering grade is 3. Influenced by various complex factors such as site management and unexpected events, the construction progress of the project is seriously lagging behind. According to the actual progress of the project, the dam filling elevation reaches 2316.00 m before the flood season in a certain year, which exceeds the upstream cofferdam 2308.00 m. The dam flood standard is 100-year standard. However, the ecological water supply tunnel is still in the stage of in-tunnel concrete lining, and the project needs to rush the concrete construction lining in the flood season. In order to ensure that the water level rises after the main flood season, the floodwater is prevented from entering the ecological water supply tunnel to cause structural damage and injury, and the safety of the construction personnel and equipment in the tunnel is ensured, a tunnel water-retaining plug needs to be specially set upstream thereof.

[0095] When the length of the plug is preliminarily designed, according to the relevant regulations and specifications “Hydraulic Tunnel Design Specification” (NB / T 10391-2020), the plugging body of the tunnel construction branch tunnel should be consistent with the grade of the tunnel structure. Therefore, the grade of the tunnel plug is 3, the floodwater standard of the water-retaining flood is 20 years, and the design flood level is 2294.50 m. The cross section of the construction branch tunnel is 7.0 m x 8.0 m, and the bottom elevation of the plugging body arrangement position is 2259.00, so the acting water head is 35.5 m. Since the construction branch tunnel of the project is not lined, the interface between the concrete and the surrounding rock is taken as the control sliding surface. The design length of the tunnel plug is calculated to be 14.46 m by using the partial coefficient limit state design method.

[0096] In order to detect the anti-sliding stability failure risk rate of the water-retaining plug designed above, the scheme provided by the present application is implemented as follows:

[0097] I. Establishing an ultra-high dam construction tunnel plug anti-sliding stability failure risk model:

[0098] The interface sliding of the tunnel plug of the project is the main structural failure mode of the tunnel plug. The load effect of the tunnel plug is the thrust of the water load on the upstream face of the plug caused by the highest construction flood level, the structural anti-sliding force is the friction between the concrete and the surrounding rock and the cohesion of the material, the established limit state equation of the anti-sliding stability of the tunnel plug during the main flood period of the construction of the super-high dam is:

[0099] Z = P H (max(Z m (t)))-(f'∑W+C'(λA1+A2)) = 0

[0100] Wherein, Z m (t) is the dynamic change process of the water level of the reservoir before the dam during the main flood period of the dam construction; P H (max(Z m (t))) is the thrust of the water load on the upstream face of the plug caused by the highest flood level; f' is the shear friction coefficient between the concrete of the plug and the surrounding rock; ∑W is the sum of all normal forces on the sliding surface, unit MN; C' is the cohesion between the plug and the concrete or the concrete and the surrounding rock, unit MPa; λ is the effective bonding area coefficient of the side wall; A1 is the effective shear surface contact area of the side wall, unit m 2 ; A2 is the effective shear surface contact area of the bottom surface, unit m 2 .

[0101] The tunnel plug during the main flood period of the construction of the project is at risk of structural sliding failure due to the comprehensive influence of random factors such as hydrology, hydraulics, and material mechanics parameters. Among them, the water load caused by the highest water level in the upstream reservoir area has a certain randomness due to the influence of random factors such as hydrology, hydraulics, and water level-storage capacity relationship; the randomness of material mechanics parameters makes the total resistance of the plug have a certain randomness. Considering the randomness of each main influencing factor, the mathematical model of the anti-sliding stability failure risk R of the tunnel plug before the flood of the super-high dam is established as follows:

[0102] R = P(P H (Z m (t)) > f'∑W+C'(λA1+A2))

[0103] Wherein, P(·) represents the probability of (·) condition being true.

[0104] Secondly, the main factors influencing the randomness of the water load are systematically analyzed, and the distribution parameters of each random factor are determined:

[0105] (1) Hydrological random parameters:

[0106] According to the measured annual maximum flow series of the hydrological station, the non-continuous series of the investigated annual historical flood is added to form a frequency calculation. The empirical frequency of the historical flood and the measured series is calculated by the expectation formula, the initial estimated parameter is calculated by the moment method, and the hydrological random parameter μ is determined by the visual fitting method Q = 2540 m 3 / s, C v = 0.33, C s / C v = 5.0.

[0107] (2) Hydraulic random parameters:

[0108] The initial diversion tunnel section size is 15.0 m x 19.0 m, the discharge capacity coefficient of the discharge building is subject to triangular distribution, the value range is generally in the range of 0.97-1.05, according to the experience of similar projects, the distribution parameters are 0.97 (lower limit), 1.00 (median), and 1.05 (upper limit).

[0109] (3) Water level-storage capacity relationship coefficient random parameters:

[0110] The water level-storage capacity relationship coefficient of the project is subject to triangular distribution, and the distribution parameters are 0.99 (lower limit), 1.00 (median), and 1.01 (upper limit) according to the experience of related projects.

[0111] III. Systematic analysis of the randomness of the main factors affecting the resistance to determine the distribution parameters of each random factor:

[0112] (1) Random parameter analysis of side wall contact coefficient:

[0113] The side wall contact coefficient is subject to triangular distribution, and the range is generally in the range of 0.3-0.8, according to the experience of similar projects, combined with the construction management and technical level of the construction unit of this project, the random distribution parameter of the side wall contact coefficient is 0.5, and the final determination of the side wall contact coefficient λ distribution parameter is 0.3 (lower limit), 0.5 (median), and 0.8 (upper limit).

[0114] (2) Random parameter analysis of material:

[0115] The plug concrete grade is C25, and the surrounding rock grade is grade IV surrounding rock. Referring to the relevant data, combined with the construction site conditions, the material random parameter statistical characteristics are obtained as shown in Table 1:

[0116] Table 1 Material random parameter statistical characteristics

[0117] Random variable Mean Coefficient of variation Distribution type f' 0.7 0.2 Normal C' 0.4 0.1 Normal

[0118] Four, the random simulation of the water load caused by the highest flood level during the main flood season and the total anti-sliding force caused by the tunnel plug, the calculation of the anti-sliding stability failure risk rate:

[0119] Determine the total number of model simulation calculations that meet the calculation accuracy requirements, perform random simulation of the water load caused by the highest flood level during the main flood season and the total anti-sliding force caused by the tunnel plug, and simulate the anti-sliding stability failure risk rate R of the tunnel plug during the main flood season of the super-high dam construction.

[0120] To ensure calculation accuracy, when the number of simulations is greater than 100,000 times, the calculation results tend to be stable and small. Therefore, the total number of simulation is designed to be 100,000 times. In the case of a designed plug length of 14.46m, after 100,000 times of simulation calculation, it is statistically obtained that the number of plug anti-sliding stability failures caused by the water load of the highest flood level in front of the dam exceeding the total anti-sliding force that the tunnel plug can generate is 24 times, and the failure risk R is 0.24%. It is shown that the designed plug length has high safety reliability, and the failure risk R is much smaller than the design risk rate of 5% of the 20-year design standard, which also shows that the designed plug length has a large safety margin. Subsequently, the plug length can be further optimized so that the calculated anti-sliding stability failure risk rate is close to the design risk rate of 5%, thereby obtaining the optimal plug length design value under the premise of meeting the design requirements of reliability, and thereby reducing the plug engineering investment and shortening the construction period.

[0121] Finally, it should be noted that the above embodiments are only preferred embodiments and do not limit the present application. It should be noted that for those skilled in the art, without departing from the purpose of the present application and the scope of the claims, a number of modifications, equivalent replacements, improvements, etc. can be made, which should be included in the protection scope of the present application.

Claims

1. A method for detecting the failure risk rate of the anti-sliding stability of a tunnel plug during the main flood period of a super-high dam construction, characterized in that it comprises the following steps: S1. Establishing a failure risk model for the anti-sliding stability of the tunnel plug during the main flood period of a super-high dam construction; S2. Determining the distribution parameters of the main random factors affecting the water load; ； Wherein, R represents the anti-sliding stability failure risk of the tunnel plug during the main flood period of the super-high dam construction; represents the water level dynamic change process of the reservoir flood regulation before the dam during the main flood period of the dam construction; is the water load thrust generated by the highest flood level on the upstream face of the plug; is the shear friction coefficient between the plug and the surrounding rock; is the total normal force on the sliding surface and is the cohesion between the plug and the concrete or between the concrete and the surrounding rock; is the bonding effective area coefficient of the side wall; is the effective shear surface contact area of the side wall; is the effective shear surface contact area of the bottom surface; P(·) represents the probability of the condition (·) being true. S3. Determining the distribution parameters of the main random factors affecting the anti-sliding force; S4. Based on the designed length of the tunnel plug, combining the distribution parameters of the main random factors affecting the water load and the anti-sliding force, performing random simulation of the water load generated by the highest flood level during the main flood period of the dam for flood control and the total anti-sliding force that the tunnel plug can generate; S5. According to the random simulation results, estimating the failure risk rate of the anti-sliding stability of the tunnel plug during the main flood period of a super-high dam construction. In step S2, the determined distribution parameters of the main random factors affecting the water load include:

2. The method according to claim 1, wherein the method comprises the steps of: determining the failure risk rate of the anti-sliding stability of the tunnel plug of the super-high dam construction during the main flood season according to the first and second parameters. the construction flood peak, which is assumed to follow a P-III distribution; the discharge capacity coefficient of the diversion tunnel, which is assumed to follow a triangular distribution; the water level-storage capacity relationship coefficient, which is assumed to follow a triangular distribution. In step S3, the determined distribution parameters of the main random factors affecting the anti-sliding force include:

3. The method according to claim 2, wherein the method comprises: determining the failure risk rate of the anti-sliding stability of the tunnel plug of the super-high dam construction during the main flood season according to the first and second parameters. the effective area coefficient of the side wall bonding, which is assumed to follow a triangular distribution, and its probability density function is: the shear friction coefficient and cohesion of the plug material, which are assumed to follow a normal distribution, and their probability density functions are: ； wherein, is a lower limit value, i.e. the minimum bond effective area coefficient of the side wall; is a median value, estimated according to the technical level of the construction unit and the site management; is an upper limit value, i.e. the maximum bond effective area coefficient of the side wall; In step S4, based on the designed length of the tunnel plug, combining the distribution parameters of the main random factors affecting the water load and the anti-sliding force, performing random simulation of the water load generated by the highest flood level during the main flood period of the dam for flood control and the total anti-sliding force that the tunnel plug can generate, including: ； wherein is the mean of the random variable parameter of the coefficient of friction against shear or cohesion ; is the standard deviation of the random variable parameter of the coefficient of friction against shear or cohesion .

4. The method according to claim 3, wherein the method comprises: determining the failure risk rate of the anti-sliding stability of the tunnel plug of the super-high dam construction during the main flood season according to the first and second parameters. the random simulation process of the water load generated by the highest flood level during the main flood period of the dam for flood control includes: Firstly, the total number of model simulation calculation satisfying the calculation precision requirement is determined based on the Monte Carlo method ; Then, combined with the distribution parameters of the main random factors affecting water load and anti-sliding force, the random simulation of the total anti-sliding force generated by the water load of the highest flood level of dam flood control in the secondary flood season and the tunnel plug can be performed. The random simulation of the total anti-sliding force generated by the water load of the highest flood level of dam flood control in the secondary flood season and the tunnel plug can be performed.

5. The method according to claim 4, wherein the method further comprises: determining the failure risk rate of the anti-sliding stability of the tunnel plug of the super-high dam construction during the main flood season according to the first and second failure risk rates of the anti-sliding stability of the tunnel plug of the super-high dam construction during the main flood season. generating a random number of the construction flood peak to simulate the construction flood process; the random simulation process of the total anti-sliding force that the tunnel plug can generate includes: The reservoir storage capacity relationship coefficient random number is generated to simulate and fit the water level-storage capacity relationship curve. A random number of discharge capacity coefficient is generated to simulate and fit the discharge capacity curve of the diversion. The highest flood level in front of the dam during the main flood season is obtained by simulating flood regulation calculation simulation ; Water load is calculated by the highest flood level in front of the dam during the main flood season by simulation .

6. The method according to claim 5, wherein the method further comprises: determining the failure risk rate of the anti-sliding stability of the tunnel plug of the super-high dam construction during the main flood season according to the first and second failure risk rates of the anti-sliding stability of the tunnel plug of the super-high dam construction during the main flood season. In step S5, according to the random simulation results, estimating the failure risk rate of the anti-sliding stability of the tunnel plug during the main flood period of a super-high dam construction, including: Coefficient of effective bonded area of a side wall random number; Shear friction coefficient Coherence Random number; Total resistance to sliding force that can be generated by a tunnel plug .

7. The method according to claim 6, wherein the method further comprises: determining the failure risk rate of the anti-sliding stability of the tunnel plug of the super-high dam construction during the main flood season according to the first and second failure risk rates of the anti-sliding stability of the tunnel plug of the super-high dam construction during the main flood season. ​ According to The simulation results of the random simulation of the total anti-sliding force generated by the water load of the highest flood level of the dam during the secondary flood season and the tunnel plug, the statistical analysis of the water load of the highest flood level in front of the dam simulated The number of times the total anti-sliding force generated by the tunnel plug is exceeded , which is recorded as ; Then according to The risk rate R of stability failure of the tunnel plug of the super-high dam construction during the main flood season is estimated.

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