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Abstract Single specimen is used for rheological test method under multistep loading，which avoids the discrete affection of specimen for rheological deformation. But the deformation of the later loading contains the creep deformation induced by the former loading of all levels by this method，which always makes people confused. The memory effect of loading history for the rheological media is analyzed detailedly；and the concrete steps and mathematical basis of the data processing are proposed. Based on the triaxial rheological test results of diabase in dam foundation of Dagangshan hydropower station，the typical character of rheological curves is analyzed. According to loading creep test curves under different stress levels，by connecting the instantaneous elasticity Hooke body，visco-elastoplastic Schiffman body and nonlinear viscoplastic body in series，a new nonlinear visco-elastoplastic rheological model of rock is proposed. Through introducing the nonlinear viscoplastic component，this rheological model can describe the transient creep stage，steady-state creep stage and tertiary creep stage. Three-dimensional rheological and creep equations under constant stress are deduced. On the basis of complete creep curves gained by rheology equipment，the rheological parameters are inversed. The comparison between nonlinear rheological model and experimental curves shows that two curves accord well with each other，and the proposed nonlinear visco-elastoplastic rheological model is available and reasonable.
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Received: 28 January 2011
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2011, Vol. 30 
