Nonlinear Seismic Response Of Xiluodu Arch Dam Considering Influence Factors

Xiluodu arch dam,which is 285.5m high,is the third largest dam in the world.Xiluodu arch dam is located in southwest of China,where the physical geography is very complicated and strong earthquakes occur frequently.After Xiluodu arch dam started impounding,valley width decrease is observed.The nonlinear seismic response of Xiluodu arch dam requires more research.Many factors,such as concrete damage cracking,radiation damping effects of foundation,joint opening and dam-water interaction,influent high arch dam seismic performance.Using dam-foundation-water nonlinear coupled model which is built by Tsinghua University,this study focuses on the nonlinear seismic response of Xiluodu arch dam considering influence factors like different joint models,different dam-water interaction models,valley width decrease and aged concrete.Some innovations are listed as follow:1.This study compares perfect keyway and no keyway.If the keyway is perfect in an arch dam,adjacent dam blocks cannot move tangentially.If there is no keyway in an arch dam,adjacent dam blocks can move tangentially according to Coulomb's law.The nonlinear seismic response of Xiluodu arch dam with perfect keyway is smaller than that with no keyway,such as transverse joints aperture decrease and less damage near upper outlet or base surface.The keyway in arch dam improves effectively the stress state to have better seismic performance.2.Using different reservoir models is to simulate dynamic water pressure.Westergaard model is frequently used.The second reservoir model is semiunbounded reservoir model.The nonlinear seismic response of Xiluodu arch dam with Westergaard model,which is bigger than that with semi-unbounded reservoir model,is conservative,such as transverse joints aperture increase and the upstream or downstream extreme displacement increase.3.After Xiluodu arch dam started impounding,valley width decrease is observed.The valley width decrease is simulated with the monitoring result to analyze static state.Then more research is carried out to analyze seismic performance considering valley width decrease.Considering valley width decrease,the nonlinear seismic response of Xiluodu arch dam is higher.With the decrease in valley width,there is a corresponding increase in the nonlinear seismic response.To research seismic performance of Xiluodu arch dam,valley width decrease and more valley width decrease are considered.The decrease in valley width has negative impact for the arch dam seismic resistance,especially near upper outlet and base surface,where there is more damage.4.As the age of concrete increases,the concrete mechanical property will be lower with the chemo-mechanical damage.The nonlinear seismic response of Xiluodu arch dam with aged concrete is higher,such as transverse joints aperture increase and more damage near upper outlet or base surface.The nonlinear seismic response of Xiluodu arch dam with coupled model,which considers aged concrete and valley width decrease simultaneously in the first time,is higher,such as transverse joints aperture increase and more damage on the toe wall.