Analysis Of Interaction Between Gravity Dam-reservoir Water-siltation Layer-foundation

There are more and more water conservancy projects are running or have been put into use.One of the characteristics of water conservancy projects is that once the accident happens,the consequences are serious and it's impact on downstream protected areas is enormous,so,their safety is of great importance.most of the place where dams located are seismic zones.Therefore,the study of the dynamic response and failure mechanism of dams under seismic loads is necessary.At the same time,after the gravity dam has been built and operated for a certain period of time,alluvium will gradually accumulate in front of the upstream dam.The change of the thickness of the alluvium and its physical properties will have some influence on the dynamic response of the dam body during the earthquake.The gravity dam-reservoir-alluvium-foundation under the earthquake will be considered as a complex system.In order to accurately analyze the characteristics and dynamic response of dam during earthquake,the following contents are studied and analyzed in this paper:(1)Under earthquake,the interaction of gravity dam-reservoir water-alluviumfoundation system is a typical fluid-solid coupling phenomenon.The deformation and movement of the dam will affect the deformation and movement of the reservoir water.Conversely,the movement and deformation of the reservoir water will also affect the movement of the dam.This paper will introduce the principles of fluid-solid coupling and its related theory.(2)In order to study the dynamic response and damage form of dam body under earthquake,the fluid-solid coupling model of gravity dam-reservoir-alluviumfoundation system under earthquake is analyzed.The acceleration,displacement and hydrodynamic pressure of dam body are mainly analyzed.and the location where cracks and damages are most likely to occur in dam bodies under earthquake is discussed.The results show that when earthquake occurs.the dam heel and upstream and downstream of the dam neck is the easiest part to crack and the position where maximum tensile stress appear.(3)The influence of the existence of alluvium and its physical properties on the dynamic response of dam body under earthquake is mainly studied.Firstly,the fluid-solid coupling model with or without alluvium is compared and analyzed.Secondly,the influence of different thickness of alluvium is studied.Finally,the influence of different density of alluvium is studied,and the displacement of dam body and acceleration and hydrodynamic pressure are compared and analyzed.The results show that the existence of alluvium can reduce the seismic response of the dam to a certain extent,which is beneficial to the seismic safety of gravity dam,and the dynamic response of the dam decreases with the increase of alluvium's density.