Abstract

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Title:: Study on Unsteady Creep Constitutive Model Based on Creep Experiment of Chengdu Clay

Author(s):: REN Peng; WANG Peng; TANG Yin; Sichuan Testing Center for Construction Engineering Quality, Sichuan Institute of Building Research

Keywords:: clay; creep model; fractional derivative; unsteady coefficient; fitting analysis

Abstract:: Aiming at the problem of adverse effects of the creep characteristics of clay on engineering, the conventional threeaxis consolidation undrained test and threeaxis consolidation undrained creep test on Chengdu clay were studied. The unsteady performances of creep characteristics, isochronous stressstrain relationship, elastic modulus and the viscosity coefficient of Chengdu clay were analyzed. Meanwhile, based on the fractional derivative theory, replacing the conventional viscous elements with software components, and considering the unsteady characteristics of the elastic modulus and viscosity coefficient of clay, the unsteady creep constitutive model of Chengdu clay was constructed, and the constitutive model was fitted and identified. Through the above analysis, the longterm strength value of Chengdu clay was obtained. The results show that the unsteady performances of elastic modulus and viscosity coefficient of Chengdu clay include two aspects of timeliness and loading characteristics. The creep model elements include transient elastic elements, viscoelastic elements and viscoplastic elements. The variation rule of the fitting parameters is consistent with the indoor test rule, especially for the accelerated creep stage. The constructed model is reasonable and reliable.