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Hydropower projects are rapidly developing in China at present,and a number of high dams and large reservoirs are currently under construction or will soon be built.These large projects are mainly located on the great rivers in West China with complicated topographical and geological conditions.Evaluation of stability and safety of these high dam projects is an important topic.Geomechanical model test is one of the main methods to study the global stability of high dam and foundation.In this paper,a comprehensive testing method that combines overloading and strength reduction in a model is proposed.In this method,both the influence of excessive flooding and the effects of strength reduction of rock masses and weak structural planes on dam stability are considered.Thus,the comprehensive testing method can accurately incorporate multiple factors that affect the global stability of high dam and its foundation.Based on the failure testing principle and model similarity theory,a similarity relation formula for safety evaluation through comprehensive test is established.A new model material,temperature-dependent analogous material,is also developed.By rising the temperature and reducing the strength of the model material,the mechanical behaviors resulting from gradual strength reduction can be simulated.Thus,the comprehensive testing method is realized in a single model.For case studies,the comprehensive geomechanical model test is conducted for Jinping Ⅰ and Xiaowan high arch dam projects.