Modified Terzaghi consolidation curves with effective stress-dependent coefficient of consolidation

Abuel-Naga, Hossam; Pender, Michael

doi:10.1680/geolett.12.00005

Cited by 15 publications

(4 citation statements)

References 29 publications

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“…An additional benefit of the TAS method is that it not only enables the determination of the crack damage stress but also of pressure diffusion coefficients. As pressure diffusion coefficients are identical to coefficients of consolation (the difference being the method by which they are determined), they can be used to calculate permeabilities (Wang, 1993;Robinson, 1998;Abuel-Naga and Pender, 2012;Di Francesco, 2013). In contrast to the crack damage stress, where only phase 5 yields results, pressure diffusion coefficients can be calculated from the outlet pressure changes in phases 4 and 5.…”

Section: Gain In Informationmentioning

confidence: 99%

Crack damage stress in fully saturated, permeable rocks: A new detection procedure

Schumacher,

Gräsle

2024

Preprint

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Abstract. To detect the crack damage stress also known as onset of dilatancy in fully saturated rocks, we propose a new procedure which combines an innovative measurement technique using pore pressure diffusion with the well known technique of finding the pore pressure maximum. A precise determination of the crack damage stress is required to establish parameter dependencies and ultimately to develop a constitutive equation for the crack damage stress, which is of significant interest e.g. for the long-term safety analysis of repositories for radioactive waste. The new technique monitors the true axial strain as indicator for the crack damage stress during a pore pressure diffusion test. In addition to the crack damage stress, this new true axial strain method simultaneously yields pore pressure diffusion coefficients, thereby maximising the information gain. The true axial strain method was developed based on a multi-cycle, long-term experiment of one sample of Passwang Marl, but it can be applied to other types of rocks, which is demonstrated on a Bunter Sandstone.

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Section: Gain In Informationmentioning

confidence: 99%

Crack damage stress in fully saturated, permeable rocks: A new detection procedure

Schumacher,

Gräsle

2024

Preprint

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“…In Terzaghi's theory, the stress-strain relationship of soils is linear, resulting that soil compressibility is a constant in the vertical direction. However, the compressibility of soft soils is closely related to the initial and final effective stresses along the depth (Davis and Raymond 1965;Gibson et al 1967;Poskitt 1969;Hawley and Borin 1973;Abbasi et al 2007;Abuel-Naga and Pender 2012;Abuel-Naga et al 2015;Wu et al 2016). Due to the stress history and geological process, the initial effective stress and pre-consolidation pressure normally increase with depth in the field, thus, the soil compressibility varies with depth of the soft soil layer nonlinearly when the ground is subjected to an external loading (Craig 2004).…”

Section: Introductionmentioning

confidence: 99%

Development and Verification of a New Simplified Method for Calculating Settlement of a Thick Soil Layer with Nonlinear Compressibility and Creep

Feng

Yin

2020

Int. J. Geomech.

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The variable compressibility is necessary to be considered in settlement calculation of soft soil stratums, especially for thick soil layers. In this study, to calculate the consolidation settlement of a thick soil layer with creep, a new simplified method is presented using Zhu and Yin method (2012) to consider the nonlinear compressibility. The creep settlement during the consolidation stage is calculated, examined, and discussed for the thick soil layer. In the new simplified method, α is an important parameter to approximately consider the couple of consolidation and creep. It is found that the value of α in the new simplified method is a variable and is suggested to take α =Uz as a simplification. A series of cases including different thicknesses of soil stratums, different OCR values, different surcharge loadings, and different values of creep parameter are studied to verify the new simplified method by comparing our calculated values with the finite element simulated results. Subsequently, a typical and well-known Väsby test fill project with 50 years' measured data is selected as a thick soil layer example to illustrate the feasibility of the new simplified method to be used in practice. Both the new simplified method and finite element modelling are used to obtain the ground settlements. It is found from the comparison that the calculated results from the new simplified method and the FE modelling are in good agreement with the measured data.

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“…Such variations would inevitably affect the development of porewater pressure and surface settlement. Many attempts have been made to derive analytical solutions for traditional 1D consolidation problems considering the nonlinear variations of soil permeability and compressibility (Davis and Raymond 1965;Gibson et al 1967;Gibson et al 1990;Xie et al 2002;Lekha et al 2003;Indraratna et al 2005;Geng et al 2006;Walker and Indraratna 2006;Cai et al 2007;Hu et al 2009;Walker et al 2012;Abuel-Naga and Pender 2012;Zhu and Yin 2012;Hsu and Tsai 2015). However, the analytical solution for electroosmotic consolidation with variable soil parameters has seldom been studied.…”

Section: Introductionmentioning

confidence: 99%

Analytical Solution for Electroosmotic Consolidation Considering Nonlinear Variation of Soil Parameters

et al. 2017

Int. J. Geomech.

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Electroosmotic consolidation can be used as an efficient technique for soft soil improvement. Considering the limitation in previous theories that soil parameters keep constant during electroosmotic consolidation, the nonlinear relationships between soil compressibility, hydraulic and electroosmosis conductivities, and void ratio are incorporated in a one-dimensional model in the present study. The analytical solutions for the ultimate excess pore-water pressure and surface settlement are derived. A comparison between the proposed analytical solutions and traditional theory indicates that the nonlinear variation of hydraulic conductivity results in a larger ultimate excess pore-water pressure, whereas the nonlinear variation of electroosmosis conductivity leads to a smaller one. The effects are more significant for soils with higher compressibility. The nonlinear variation of soil compressibility exhibits remarkable impact on the development of excess pore-water pressure when the nonlinear variations of hydraulic and electroosmosis conductivities are considered. Compared with the ultimate excess pore-water pressure, the impact of nonlinear variations of soil parameters on the ultimate surface settlement is less significant.

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Modified Terzaghi consolidation curves with effective stress-dependent coefficient of consolidation

Cited by 15 publications

References 29 publications

Crack damage stress in fully saturated, permeable rocks: A new detection procedure

Crack damage stress in fully saturated, permeable rocks: A new detection procedure

Development and Verification of a New Simplified Method for Calculating Settlement of a Thick Soil Layer with Nonlinear Compressibility and Creep

Analytical Solution for Electroosmotic Consolidation Considering Nonlinear Variation of Soil Parameters

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