Effective Stress in Unsaturated Soils: A Thermodynamic Approach Based on the Interfacial Energy and Hydromechanical Coupling

Nikooee, Ehsan; Habibagahi, Ghassem; Hassanizadeh, S. Majid; Ghahramani, A.

doi:10.1007/s11242-012-0093-y

Cited by 87 publications

(102 citation statements)

References 39 publications

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“…The effective stress is defined using the Bishop's effective stress formulation [50] and the Khalili and Khabbaz [51] expression for the effective stress parameter. Since the suction stress is not in the main focus of this paper, more recent papers on this topic can be found elsewhere (e.g., see [52][53][54][55] and [56]). The results show that the effective stress approach works well for the results obtained on the undisturbed specimens in the range of the effective stress considered 8 Geofluids in these tests, during both the drying and the wetting processes.…”

Section: Test Resultsmentioning

confidence: 99%

Soil-Water Characteristic Curve of Residual Soil from a Flysch Rock Mass

et al. 2018

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Depending on the nature of the material and suction range, laboratory measurements of the soil-water characteristic curve (SWCC) can be time-consuming and expensive, especially for residual soils, in which a wide range of particle sizes and soil structures typically results in SWCCs that cover a wide range of suction. Investigations of the SWCCs of residual soil from flysch rock masses are rare, and so far, no results were presented in the literature which were obtained by performing measurements on undisturbed specimens. In this paper, a detailed examination of water retention characteristics is performed for a specific type of residual soil (CL) formed by the weathering of a flysch rock mass. Measurements performed by using different techniques and devices on intact specimens were successfully combined to obtain the SWCC during both drying and wetting processes, under different stress conditions, and from saturated to air-dried conditions. Used procedures are suitable for the determination of SWCCs of soils that undergo volume changes during the drying or the wetting process, since instantaneous volumetric water content can be determined. Results presented in this paper can be used to assess the influence of desaturation of the residual soil covering flysch slopes during dry summer periods by providing key-in material properties required to analyze the transient rainfall infiltration process.

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Section: Test Resultsmentioning

confidence: 99%

Soil-Water Characteristic Curve of Residual Soil from a Flysch Rock Mass

et al. 2018

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“…There are various formulations for the effective stress parameter. As discussed by Nikooee et al (2013) and Pereira et al (2010), degree of saturation is not a good candidate for the effective stress parameter, especially in fine grained soils [5,6]. Recently Lu et al (2010) suggested the use of effective degree of saturation for the effective stress parameter to account for the fact that the immobile water does not contribute to the mechanical behaviour of unsaturated soils [7].…”

Section: Formulating the Effective Stress In Unsaturated Elementsmentioning

confidence: 99%

A study on the saturation degree dependency of the seismic behaviour of retaining walls

2016

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Abstract. Retaining walls are important geotechnical structures that are often used in soil slopes and trenches to bring ground surface at appropriate level for the construction of roads, highways and buildings. It is common practice to assume that the soil behind a retaining structure is either fully saturated or completely dry. However, for the case the soil is partially saturated, mechanical behaviour of the soil above the water table is different than that of the dry soil. Thus, it is necessary to investigate the effect of the variations of degree of saturation on lateral pressure behind retaining walls. In this research, the seismic behaviour of unsaturated soils behind a retaining structure is analysed. A finite difference code was employed to conduct the necessary analyses and a series of equivalent linear analyses is performed to reveal the effect of the degree of saturation on the general response of the retaining structures. The required functions for unsaturated zone were defined and implemented in the code. For this purpose, a soil water retention function was employed and the soil shear modulus is assumed to vary with the mean effective stress for both saturated and unsaturated zones which naturally introduces the required hydro-mechanical coupling in unsaturated and saturated zone. The results of the analyses compared to the conventional methods which does not include the unsaturated mechanical properties, indicate that in the unsaturated state, the increase in the effective stress, and hence, the shear modulus considerably affects the seismic forces on the retaining wall.

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“…saturated soils (e.g. Khalili 2000&2002;Pereira et al 2005;Gray and Schrefler 2001;Nikooee et al 2013;Borja & Koliji 2009), we wish to explore an alternative path in this paper. The key idea is to (i) observe the micromechanics, (ii) propose an abstract representation of the observed micromechanisms, and then (iii) embed them in a constitutive model.…”

Section: School Of Civil Engineering University Of Sydneymentioning

confidence: 99%