The Research On Static Characteristics And Duncan-Chang Model Parameters Of Rockfill Material Under High Stress Condition

In recent years, our country is planning a number of super high earth rock dam of 300m, and to carry out the terrain, geological exploration, research and design work. Because super high earth rockfill dam are in regions of western high elevation and complex topographic and geological conditions, and super high earth rockfill dam of 300m at home and abroad are lack of available reference for engineering construction experience, and super high embankment dam's construction will face a series of technical problems, so its construction technical feasibility and the safety problems cause the concern at home and abroad.On the one hand, the research of rockfill material needs to start from the angle of dam deformation control. In order to direction the settlement and deformation of the dam, the hard rock with good grading should be chosen, and the porosity of the rockfill is controlled at a low level, so that the rockfill has a high density and compression modulus. At the same time, with the increasing height of dam, the engineering characteristics of rockfill materials under high confining pressure and high stress condition are different, so The research work should be carried out in combination with the indoor large three axis shear test research and so on. On the other hand, some domestic dam stress deformation inversion analysis showed that Duncan Chang EB model on the whole is applicable, and it can basically reflects the basic rules of stress and strain of dam. But existing computational models and test methods still need further improvement by analyzing the existing problems of model for super high earth rockfill dam of 300m to provide more accurate reference information for prediction of engineering mechanical properties.In view of the above situation, this paper has carried out the following work:(1) A series of large scale triaxial compression tests under high confining pressure for rockfill material of a rockfill dam are carried out in different gradations of saturated samples. And the mechanical properties of three kinds of saturated samples under high stress condition are compared and analyzed.(2) A series of large scale triaxial compression tests under high confining pressure for rockfill material of a rockfill dam are carried out in unsaturated samples. And the mechanical properties of saturated samples and unsaturated samples under high stress condition are compared and analyzed.(3) The problem of Duncan Zhang model under high stress condition is analyzed, and the method of determining the parameters of the model is improved according to the existing problems of the model. The improved model was verified by inverse fitting, The results indicate that it can better reflect stress-strain characteristics of rockfill material under high confining pressure by considering effect of break ratio, so it is suggested that the effect of confining pressure on break ratio should be considered when the static analysis of super high earth-rock dam is carried out.