The Analysis Of Seepage-stability And Seismic Response Of The Concrete Face Rockfill Dam Under Saturated And Unsaturated Conditions

Concrete face rockfill dam is one of the most typical dam types of the earth-rock dam which is widely used with a lower construction cost and can be constructed using local materials in a variety of complex environments.With the characteristics of simple construction,easily understood process and low construction cost,the earth-rock dam,due to its own advantages,has become the first-choice dam type in complex geological conditions,such as river bed and rivervalley where there is deep overlying layer,complex geologicstructure,frequent earthquake.However,according to existing data and documents,the earth-rock dam holds a higher percentage of all the damaged dams than other dam types.Aiming at the existing problems of earth-rock dam,further research is needed to solve the problems of safety,applicability and economy of earth-rock dam.On the basis of the research and analysis of a concrete face rockfill dam in process in Yunnan Province,combining with the theoretical knowledge of earth-rock dam and relevant practical engineering experience,in this paper we will conduct the analysis and study of the earth-rock dam from the following aspects:(1)On the foundation of finite element method,we studied the seepage problem of concrete face rockfill dam under saturated / unsaturated seepage constitutive relation.When the dam body is in unsaturated condition,above the saturation line,there is matrix suction but no pore water pressure while there is excess pore water pressure below the saturation line.Therefore,the whole area is considered as the area for seepage calculation.(2)According to the theoretical basis of finite element method,Mohr-Coulomb nonlinear criterion is used in the numerical simulation calculation of earth-rock dam and the hierarchical loading calculation mode is also used to simulate the construction process and to study the stress-strain of the dam body under various Working Conditions.(3)Pseudo static and dynamic analysis methods are used to conduct the earthquake response analysis on this dam.At the same time,detecting points are set to analyze the distribution law of seismic displacement and seismic dynamic stress on the key positions of the dam body under various working conditions.What's more,we focus on the analysis of stress concentration parts(such as toe slab,face plate,foundation surface,dam crest and downstream dam slope)and study the response regularity of the concrete face rockfill dam to earthquake.(4)Two-dimensional and tridimensional simulation calculation of seepage,stress,deformation,slope stability and seismic response is conducted for concrete face rockfill dam under various conditions.The distribution law of stress,deformation,seepage and seismic response of concrete face rockfill dam under various conditions is also summarized.What's more,it provides scientific basis for guiding the safe operation and scientific management of seepage and seismic resistance of the earth-rock dam and its system.With the practical engineering example,not only numerical simulation,but also engineering practice is used as scientific research method in this paper.Further more,the main research content of this paper is the synthesis problem about anti-seismic safety of the earth-rock dam,which is theoretically significant to the safety study for earth-rock dam and provides reference for the safety and reliability of the design of earth-rock dam.