Abstract:The earth-rockfill dam is the most common and economical type of dam because of its convenient construction method and ease of material supply.Many high earth-rockfill dams have been or are planned to be constructed in the west of China,an area with intense seismic activity.Some of them are sited on a deep overburden layer that has an important influence on the dynamic response of dams.In this study,we consider a domestic core wall rock fill dam still under construction as a 3D FE numerical example.The area where the dam is located has an overburden layer hundreds of meters thick,and its tectonic stability is poor.The 3D mesh used in FE calculation has been simplified appropriately.To determine the initial stress field required for the dynamic calculation,the Biot's consolidation theory was adopted to simulate the sediments of the overburden layer and the dam filling and water storage processes of the reservoir.In addition,the Duncan-Chang E-ν model was used to complete the static calculation.The equivalent linear method was used to conduct dynamic analysis;this method,proposed by Shen Z J,considers the increase and change in pore water pressure during vibration.Scholars have always considered soil as the undrained boundary in former studies.This can result in an excessive accumulation of residual pore water pressure,which does not conform to the actual situation. In this study,the residual volumetric strain obtained by the empirical formula is divided into two parts:the excess pore water pressure and residual deformation.The results show this method to be rational and useful.On the basis of the equivalent linear method,one earthquake is divided into many time intervals;a total stress method is used in the analysis of every interval,and the time difference is completed according to the Wilson-θ method.Subsequently,we calculate the increase of the residual deformation and pore water pressure of each element in every time interval and transform it into initial stress or initial strain.The static analysis is continued,and changes of the node displacement,effective stress,and element strain were obtained.The residual deformation and pore pressure are completed by the empirical formula.Every time interval is calculated in the same manner,and then,the stress and strain,residual deformation,and pore pressure can be properly derived.Residual displacement,acceleration amplification,and residual pore pressure are analyzed according to the FE results.The numerical results show good agreement with the common properties. Therefore,this adopted method is capable of investigating the dynamic response of core wall rockfill dam on deep overburden layer under strong earthquake loading.The treatment of the residual pore water pressure accumulation in the soil may have a certain reference significance for analyzing such problems.
