Creep Properties of Expansive Soils under Triaxial Drained Conditions and its Nonlinear Constitutive Model

Abstract

The creep behaviors of expansive soils play an important role in landslide prediction and long-term stability analysis. In this paper, triaxial drained compression creep tests of expansive soils were conducted on the improved stress-controlled triaxial apparatus. The test results show that only transient deformation and attenuation creep occur with low deviator stress, and the increment of axial strain increases exponentially with deviator stress increasing; while deviator stress reaches a certain value, attenuation creep, steady creep and accelerated creep all occur in a creep curve. Meanwhile, the volumetric strain presents the shear shrinkage characteristic at the initial stage of loading, and the shear shrinkage is small. With the extension of loading time, the volumetric strain gradually varies from shear contraction to dilatancy. When entering the accelerated creep stage, the development rate of volumetric strain increases sharply. Besides, isochronous stress-strain curves of expansive soils indicate that their creep process possesses nonlinear characteristics, and the nonlinear degree is related to creep time and stress level. Imitating the empirical formula of cyclic cumulative deformation of clay, a new nonlinear creep model is presented, which may well describe the creep property of expansive soils. Furthermore, critical failure stress could be obtained based on the proposed creep model. The ratio of the critical failure stress to conventional shear failure stress ranges from 70% to 80%, with average of 75.56%, therefore, critical failure stress may be estimated by conventional triaxial tests with the margin of error 5.5% within.

Creep Properties and Creep Modelling of Guilin Red Clay

“…Yang et al [7] carried out creep tests under different perimeter pressures on cured blowfill mud-consolidated soil and established a prediction formula that reflected the creep characteristics of mud-consolidated soil. Li et al [8] conducted a triaxial unloading creep test on expanded soil and proposed a nonlinear four-element creep model, which described the evolution of the axial strain of expanded soil over time, under triaxial compressive stress and under equal circumferential pressure, by comparing the experimental results with the simulation results. Li et al [9] conducted a triaxial unloading creep test on artificially frozen soil and described its creep characteristics.…”

Creep Characteristics of Soil in the Sliding Zone of Huangtupo Landslide

“…Li et al carried out triaxial tests on expansive soil and found that the soil showed shear shrinkage characteristics at the initial stage of stress loading. When soil enters the accelerated creep stage, its volume strain changes from shrinkage to expansion [17].…”

“…Based on the concept of a binary medium, Wang et al established a binary medium creep model suitable for frozen soil [24]. With the long-term research on the rheological theory of soil by various researchers, many previous rheological constitutive models applicable to geotechnical materials can be broadly classified into the following four types: the element model, the damage rheological model, the yield-surface model, and the empirical model [17,25]. The above four types of models are applicable to different working conditions and stress states.…”