Constitutive modeling for unsaturated soils considering gas hardening effect

Liu, Yan; Zhao, Cheng; Cai, Guoqing; Huang, Lu

doi:10.1007/s11434-010-4109-0

Cited by 9 publications

(4 citation statements)

References 18 publications

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“…The impact of the third term with respect to the gas phase in unsaturated soils can be found in reference, and is not discussed here. The interfacial energy has significant influence on the solid phase, liquid phase, and flow equations.…”

Section: Derivation Of Work Input Equationmentioning

confidence: 99%

Work input for unsaturated soils considering interfacial effects

Liu

Wei

Zhao

et al. 2018

Num Anal Meth Geomechanics

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Summary In this research, the interfacial energy is taken into account in the deformation work for unsaturated soils. Based on porous media theory, the thermodynamic balance equations for each phase and the interface are used to derive the work input for unsaturated soils. The work input equation serves as the basis and starting point for the choice of stress state variables, based on which the conjugate stresses and strain increments are derived. The influences of the interfaces on the effective stress and the constitutive law for the liquid phase are then discussed based on the work input equation. The effective stress can be expressed as Bishop's type, and the effective stress parameter is shown to be a function of both the degree of saturation and the interfacial area. The constitutive law for the liquid phase under dynamic condition is also presented. The relationship among interfacial area, saturation, and capillary pressure is proposed to calculate the value of the effective stress. Experimental data obtained from literature are used to validate the proposed model equations. Results show that our findings are in accordance with the existing research. Unlike the phenomenal study, our research has a rigorous theoretical basis, which lays a foundation for further research of unsaturated soils considering the interfacial effects.

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Section: Derivation Of Work Input Equationmentioning

confidence: 99%

Work input for unsaturated soils considering interfacial effects

Liu

Wei

Zhao

et al. 2018

Num Anal Meth Geomechanics

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“…Li [16,17] deduced the expressions of input work and energy balance of unsaturated soils, and developed a thermodynamics-based modelling framework. Then the variation of gas pressure is further taken into account [18,19]. In this paper, based on the porous media theory, the specific expressions of the total stress and the input work of unsaturated expansive soils with double porosity are proposed, and the energy-conjugate variables are further derived.…”

mentioning

confidence: 99%

The input work expression and the thermodynamics-based modelling framework for unsaturated expansive soils with double porosity

Zhao

Cai

et al. 2013

Chin. Sci. Bull.

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In this paper, based on the porous media theory, the specific expressions of the total stress and the input work of unsaturated expansive soils with double porosity are proposed, and then the energy-conjugate variables are further derived. We make distinctions between the effects of capillary water and adsorbed water on the soil behaviour, as well as between the deformations of micro-and macrostructure. According to the derived input work expression and the work-energy-dissipation relations for an open multiphase thermodynamic system, we establish a thermodynamics-based modelling framework for unsaturated expansive soils with double porosity. Many geomaterials, such as fissured rocks [1], natural and compacted clays [2,3] and bentonite pellet mixtures [4], have a pore size distribution with at least two dominant values of porosity, or double porosity. The two scales of porosity correspond to the micropores (matrix pores, intraaggregates or intra-pellets) and macropores (fissures, interaggregate pore or inter-pellets). The research subject of this paper is unsaturated expansive soils which consist of two overlapping but distinct continua. The macrostructure refers to the arrangement of soil particle aggregates and the relatively large pores between them. The microstructure refers to clay particles and the micropores within them. An important issue in the investigation of the behaviour of materials exhibiting two scales of porosity is the evolution of the internal structure and the proportional changes of micro-and macroporosity during the course of mechanical and wetting-drying stress paths. The compression tests [5,6] indicate that the macrostructural deformation is strongly affected by the mechanical loading of an aggregated soil while the corresponding change in the micropores is almost insignificant. The control-suction tests [4,7] exhibit that the microstructure expands (or contracts) during wetting (or drying), and the microstructural volume change is reversible. However, the macrostructural deformation is always irreversible and is related to the initial compaction density, the variation range of suction, etc.Based on the distinction between the deformations of micro-and macrostructure, Gens and Alonso [8] presented a framework for describing the behaviour of unsaturated expansive clays. Then Alonso et al. [9] further presented the stress-strain incremental relations (BExM). Mechanical coupling between both levels of structure was defined through two functions, one for wetting and the other for drying. Afterwards, a series of modifications and developments have been performed for the BExM [10][11][12].Ziegler and Wehrli [13] presented an approach which is

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“…It appears able to unify the theoretical basis of unsaturated soil mechanics [12][13][14][15][16][17]. Recently, multi-phase porous media theory was used by our research team as the basis for some useful insights into unsaturated soil mechanics including the principle of generalized effective stress and constitutive relations for unsaturated soils [18][19][20], continuum porous medium soil mechanics and its application in constitutive relationships of unsaturated soils [21], and the nonlinear multi-field coupled model for multi-constituent three-phase soils [22]. This paper is based on the above research and is centered on assessment of the theory framework proposed by Cai et al [22].…”

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confidence: 99%

Volume change behavior of unsaturated soils under non-isothermal conditions

et al. 2011

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With the development of modern geotechnical engineering practices such as the construction of high level radioactive waste repositories, exploitation and utilization of geothermal resources, energy-saving buildings and underground storage of CO 2 , research into the influence of temperature on the basic mechanical properties of unsaturated soils has become an important issue internationally. By using the work expression and considering the influence of temperature on the basic properties of unsaturated soils, the average soil skeleton stress, modified suction and temperature were selected as state variables of generalized forces in thermodynamics and the soil skeleton strain, saturation and entropy were chosen as state variables of generalized flows conjugate to the variables of generalized forces. Based on the nonlinear multi-field coupled model and by using existing experimental results, an elastic-plastic constitutive model of unsaturated soils under non-isothermal conditions was developed to analyze the influence of temperature on the deformation properties of unsaturated soils. The model was used to predict and analyze the influence of suction and temperature on the deformation properties of unsaturated soils under isotropic conditions, and was successfully verified using experimental results.

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Constitutive modeling for unsaturated soils considering gas hardening effect

Cited by 9 publications

References 18 publications

Work input for unsaturated soils considering interfacial effects

Work input for unsaturated soils considering interfacial effects

The input work expression and the thermodynamics-based modelling framework for unsaturated expansive soils with double porosity

Volume change behavior of unsaturated soils under non-isothermal conditions

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