Study On Stability And Safety Evaluation Method Of Reinforced Concrete Gravity Dam Considering Time Variation Of Parameters

Most of the concrete gravity dams in our country have entered the old age stage.Due to the influence of many uncertain factors caused by the long-term solid-liquid-gas coupling storage environment,their structures have different degrees of aging and deterioration problems,coupled with their own natural defects,which makes these projects have greater security risks.In addition,the reinforcement and repair of the dangerous reservoir dam in China will become a normal work.Although the reinforcement measures can improve the overall service performance of the dam structure in a certain period of time,it is difficult to prevent the aging of the dam materials and the evolution process of the dam structure performance.Therefore,based on the current situation of concrete gravity dam in our country,by considering the time-dependent variation of uncertain parameters of concrete gravity dam structure and the comprehensive influence of disease control measures on its service safety,the evaluation and prediction model and method of time-dependent service safety of reinforced concrete gravity dam are carried out,which will be of great importance to the operation and maintenance of concrete gravity dam and the decision-making of reinforcement Guiding significance.Based on the methods and theories of numerical simulation,interval mathematical theory,central sampling technology and interval inversion,this paper,based on the monitoring data and design data of a reinforced concrete gravity dam prototype of an old age,fully excavates and refines the monitoring data of long sequence three-dimensional prototype based on the highly nonlinear function and parameter randomness of the reinforced concrete gravity dam function With information contained,it is proposed to carry out the research on probability and non probability analysis models and methods of reinforced concrete gravity dam considering the time variation of parameters.According to this,it is the assessment and prediction of the stability and safety of the existing concrete gravity dam under the practice of multiple hazards control.The main contents are as follows:(1)Based on the discussion of the main failure path and failure mode of concrete gravity dam system,a response surface Monte Carlo method for the calculation of probability reliability of concrete gravity dam is proposed by combining the advantages of Monte Carlo method and response surface method and the theory of time-varying reliability.Combined with a practical project,the safety assessment of the dam’s strength and anti sliding stability service reliability is carried out Considering the time-varying characteristics of the structural parameters,the evolution law of the service performance is reasonably predicted.(2)The traditional reliability theory applied to the safety assessment of concrete gravity dam is considered,which is restricted by the highly nonlinear,non dominant function and the sensitivity of calculation results.Based on the convex model,the calculation model and method of non probabilistic reliability index suitable for concrete gravity dam elements and systems are developed.The main failure path and failure mode identification technology of concrete dam are studied.An inversion method of interval parameter limit of concrete gravity dam is developed by integrating monitoring model and interval theory.On this basis,a response surface method based on concrete gravity is studied The realization method of the non probabilistic reliability index calculation of the dam is combined with the example project to realize the effective evaluation of the stability and safety of the concrete gravity dam under the multi failure mode.(3)Based on the non probabilistic reliability analysis of the concrete gravity dam system,the influence mechanism of reinforcement measures on the service performance of the concrete gravity dam is studied.At the same time,the time-varying non probabilistic reliability calculation model of the reinforced concrete gravity dam is constructed by using the time-varying theory,and the practical method of the time-varying non probabilistic reliability index calculation of the reinforced concrete gravity dam system is studied.In the reinforced concrete gravity dam project,considering the dual factors such as the time variation of parameters and the implementation of a variety of control measures,the dual contribution of the practice of disease control measures and the aging attenuation of materials to the service reliability of the concrete gravity dam is analyzed from the non probability perspective.