Study On Fatigue Cumulative Damage Of Concrete Garavity Dams Under Mainshock-aftershock Seismic Sequences

The design,construction and safety of hydraulic structures have been increasingly emphasized with chinese energy system turning into developing hydropower energy.As the important water conservancy facility,the seismic research and calculation about concrete gravity dam are principal,therefore,this paper launched the study on fatigue cumulative damage of concrete garavity dams under mainshock-aftershock seismic sequences,and a RCC garavity dam is revolved in this study.what’s more,the hydraulic fracturing and dam failure are also simulated in the work.The main work as follows:Firstly,software ABAQUS is used as the platform to establish the three-di mensional model of dam-rock,ABAQUS calculated the model parameters and natural frequency of the dam.then,the damping coefficient and other key parameters are obtained.Second,the linear elastic calculation and parameters such as displacement stress and strain of the dam were analyzed.several control points were selected on the dam,exported their history curve.On the base of that,this paper discussed how the stress and strain of the concrete goes,found out the potential damage area on the dam,gave some measures to improve dam’s resistance to earthquake.Third,in order to test and prove the applicability of concrete damage plasticity model to this paper,the same model was used to define the concrete of Koyna dam,com pared the result of Koyna dam under 0.415 g earthquake to the references.Fourth,Three observed earthquake waves were applied to calculate the damage of concrete dam under 0.5g mainshock,then,one or more aftershocks kept loading on the dam until crack went throught it.The failure of dam was analyzed on the basis of damaged dam.Fifth,two kinds of loading modes were settled to figure out the concrete damage under aftershocks,one kind was set only with aftershocks,the other kind was set with both hydraulic fracturing and aftershocks.Analyzing fatigue cumulative damage of the dam under those aftershocks and hydraulic fracuring in accordance with concrete damage location,scope,amount and cracks of the dam.The results of this paper can give some reference suggest to measuring the fatigue cumulative damage of the concrete garavity dam,the damage of gravity dam could be evaluated from concrete strain,based on the results of this paper,the safety and stability of concrete structure could also be known.However,due to the complexity of earthquake and dynamic response of dam,as well as some influences this dam model didn’t take into consideration,so the research and result of this paper still are insuff icient,and further research needs to go.