| Since the middle of last century,the engineering accidents caused by the durability of concrete structure emerge in endlessly.Therefore,the research of concrete durability has become an important research content of concrete structure,and the freeze-thaw effect has become one of the important topics of concrete durability research.Freezing and thawing is the repeated freezing and thawing of water in structure in cold climate.With years of freezing and thawing,the performance of concrete changes.In order to prevent the damage of concrete in freeze-thaw environment and effectively improve the durability of concrete,we need to study the dynamic mechanical properties of concrete under freeze-thaw and the degradation law of mechanical properties after freeze-thaw.This paper mainly through the following aspects:1.Based on the uniaxial compression test of hydraulic concrete,the dynamic mechanical properties of materials are studied,and the variation rules of strength,peak strain and elastic modulus of hydraulic concrete under dynamic loading are explored.According to the hypothesis of energy equivalence and the evolution parameters of material compression damage,the dynamic damage factor is deduced,and the rate correlation formula is obtained,It provides parameters and theoretical basis for dam seismic damage analysis.2.Through the "quick freezing method" freeze-thaw cycle test on the test block,the macro change characteristics and degradation mechanism of hydraulic concrete materials are studied under different freeze-thaw cycles.The Degradation Laws of strength,peak strain and dynamic elastic modulus of hydraulic concrete under freeze-thaw cycles and dynamic loading are explored.The strength characteristics,strain at peak stress,dynamic elastic modulus and strain rate were analyzed.3.Using ABAQUS software to simulate the nonlinear response analysis of Fengman dam under earthquake action,the finite element model of Fengman dam is established.Combined with the constitutive relationship of concrete freeze-thaw test,the damage path,stress nephogram and dynamic characteristics of Fengman dam model are studied and analyzed,and the mechanical change law of RCC before and after freeze-thaw in practical application is verified and discussed. |
