Soil creep behavior: laboratory testing and numerical modelling
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AbstractSoil exhibits creep behavior, in which the deformation of soil develops with time at a state of constant effective stress. It is of significance to investigate the creep behavior of soil for geotechnical applications wherein the long-term deformation of soil is concerned. In this study, the aspects of laboratory testing and numerical modelling of soil creep were investigated. On laboratory testing aspect, a series of one-dimensional and triaxial compression creep tests were performed on clayey and sandy soils, including kaolinite, Ottawa sand, till and oil sands, to investigate the creep behavior of the soils under different conditions. The dependencies of creep rate on time, stress and inelastic strain were investigated in the creep tests. On numerical modelling aspect, several issues on modelling soil creep were investigated. It was concluded that the potential for plastic flow is also applicable to describe soil creep from experimental observations and mechanistic pictures. An elasticviscoplastic creep model for soil was proposed to describe soil creep under complex conditions. In the model, the creep rate of soil was formulated as a function of inelastic strain and effective stresses, following the way of Eulerian description of motion. Based on the proposed creep model, a methodology to accelerate creep test was developed. The energy aspect and examples of this methodology were presented as well. Moreover, numerical simulations were performed to investigate the influence of soil creep on the long-term ground settlements above a tunnel in till and on the time-dependent stress redistribution in oil sand due to cavity expansion.
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